Document:

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Exhibit 10.27

                                F5 NETWORKS, INC.

                                  STEVE GOLDMAN
                            SR. VP, SALES & SERVICES
                             2003 COMPENSATION PLAN

COMPENSATION CATEGORIES

The total compensation package is designed to provide the Sr. VP, Sales &
Services $490,833 in annual income, plus upside earnings potential, according to
the following categories:

1.    ANNUAL BASE SALARY: Compensation for managing the efforts of the Sales and
      Services teams. $310,000 payable bi-weekly in arrears.

2.    INCENTIVE COMPENSATION: Offered to the Sr. VP, Sales & Services for
      leading his team to meet their objectives. 50% of the incentive
      compensation will be based on successfully achieving each quarterly
      revenue goal. The other 50% of the incentive compensation will be based on
      achieving each quarterly EBITDA goal. Target annual income from incentive
      compensation is $180,833 at plan (~60% of base salary), plus significant
      upside for exceeding goals.

PAYMENT TERMS

The incentive compensation will be paid linearly above 80% of targeted goals.
(i.e.: 80% of the possible incentive compensation will be paid for revenues at
80% of goal, 90% is paid for revenues at 90% of goal.) There is no limit,
however both goals must hit 100% for the accelerator to apply. No incentive
compensation will be paid for results less than 80% of goals. If earned,
payments will be made quarterly.

EFFECTIVE DATE AND TERM

This plan shall take effect on October 1, 2002 and shall remain in effect until
September 30, 2003.

TERMINATION

If the Sr. VP, Sales & Services', employment terminates prior to the end of the
fiscal 2003, he will be eligible to receive incentive compensation payments only
through the end of the last full quarter employed.

NOTICES

F5 Networks reserves the right to change, alter or cancel any provision
contained within this plan upon written notice to the Sr. VP, Sales & Services.
Nothing in this plan is intended to grant a right to employment for any specific
term.

AMIGUITIES AND INCONSISTENCIES

This plan has been carefully considered and is meant to be reasonable and
complete. When circumstances occur which require special interpretation,
however, it shall be the responsibility of the CEO and the Compensation
Committee to determine the intent of the plan and to render a judgment, which is
fair to both the Sr. VP, Sales & Services, and the company.

ACCEPTANCE OF PLAN AND CONDITIONS

/s/ John McAdam               /s/ Steve Goldman
------------------------      ----------------------------
John McAdam                   Steve Goldman
CEO and President             Sr. VP, Sales & Services

November 12, 2002             November 12, 2002
------------------------      ----------------------------
Date                          Date<PAGE>

                                                                   Exhibit 10.28

                            (F5 NETWORKS LETTERHEAD)

November 02, 2000

Julian Eames
15450 SW Koll Parkway
Beaverton, OR 97006-606

Dear Julian:

I am very pleased to extend to you this offer of employment with F5 Networks.
The terms of the offer are as follows:

(1) POSITION

Vice President of Professional Services, reporting to Steve Goldman. In this
position you will be responsible for building and managing F5's global
professional and managed services business.

(2) SALARY

Your base salary will be $200,000 annually, pro-rated for the period of your
employment with F5 during the calendar year. Salary will be paid twice per
month.

(3) BONUS

You will be eligible for a performance bonus, payable quarterly, targeted at
$120,000 annually, mutually agreed to revenue and profitability objectives.

(4) EQUITY-OPTION GRANT

You will be granted options to purchase 70,000 shares of F5 common stock on your
start date. These options will be granted under the Company's Stock Option
Plan, contingent upon satisfactory completion of all employee contracts and
other employee documentation as required by F5. These options will have an
exercise price equal to the closing price of F5's stock on the date of grant,
and will vest over a four-year period. If there is a change of control of the
company, 50% of your unvested options will vest immediately.

(5) RELOCATION EXPENSES

You will be reimbursed for all reasonable and customary expenses associated
with your relocation from Portland to the Seattle area.

(6) BENEFITS

You will be eligible to participate in all F5 benefit plans. F5 Network's plan
pays 100% of the medical, dental and vision insurance costs for employees and
80% of the costs of dependent coverage. Your benefits will start on the first
day of the month following your hire date. A 401(k) plan is also provided to
full-time F5 Networks employees. You may enroll in the 401(k) plan at any time
prior to the 1st of the month following your hire date or during any subsequent
open enrollment period beginning on January 1 or July 1 of each year. Enclosed
is a brief description of these plans in addition to some of the other benefits
F5 Networks offers its employees.
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                                                                          Page 2
November 02, 2000

Your employment with F5 Networks is "at will," entered into voluntarily for an
indefinite period of time, and can be terminated at any time for any reason at
the discretion of either you or F5, so long as there is no violation of
applicable United States federal or state law. Nothing that is said or written
anyplace, including this letter, will be construed as a promise of permanent
employment or of employment for any particular length of time.

This offer is contingent upon your signing this letter and the attached
employee agreement. Please respond to this offer by faxing these signed
documents to me at (206) 272-6625.

I am really excited at the prospect of you joining F5. I look forward to you
helping us lead the company in a solid growth mode that is certain to result
in the enhancement of shareholder value and the reaping of tremendous rewards
for you and your family.

Sincerely,

/s/ Jeffrey S. Hussey
Jeffrey S. Hussey
Chairman

                         Acceptance and Acknowledgment

I accept the offer on the terms outlined in this letter to me from F5 Networks
Inc., and acknowledge and agree that there are no other oral or implied
understandings regarding my employment by F5 Networks.

/s/ Julian Eames                        Nov 2nd 2000
----------------------                  -------------
Julian Eames                            DateExhibit 10.1

                          SECURITIES PURCHASE AGREEMENT

                                  by and among

                           HEMISPHERX BIOPHARMA, INC.

                                       and

                           THE INVESTORS LISTED HEREIN

                                   Dated as of

                                October 29, 2003

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                                TABLE OF CONTENTS

                                                                            Page

1. PURCHASE AND SALE OF DEBENTURES AND WARRANTS................................1

2. BUYER'S REPRESENTATIONS AND WARRANTIES......................................2

3. REPRESENTATIONS AND WARRANTIES OF THE COMPANY...............................6

4. COVENANTS..................................................................14

6. CONDITIONS TO THE COMPANY'S OBLIGATION TO SELL.............................26

7. CONDITIONS TO EACH BUYER'S OBLIGATION TO PURCHASE..........................26

8. INDEMNIFICATION............................................................28

9. MISCELLANEOUS..............................................................29

Schedule 3(a)        -     Subsidiaries
Schedule 3(c)        -     Capitalization
Schedule 3(e)        -     Conflicts
Schedule 3(l)        -     Title
Schedule 3(n)        -     Insurance
Schedule 3(r)        -     Transactions with Affiliates
Schedule 4(u)        -     Consideration pursuant to Interferon Agreements
Schedule 4(v)        -     Certain Accounts

                                    EXHIBITS

Exhibit A          Form of Debentures
Exhibit B      -   Form of Warrant
Exhibit C      -   Form of Registration Rights Agreement
Exhibit D      -   Form of Letter of Credit
Exhibit E      -   Form of Account Control Agreement
Exhibit F      -   Form of Security Agreement
Exhibit G-1        Interferon Inventory and License Agreement
Exhibit G-2        Interferon Asset Agreement
Exhibit H      -   Form of Irrevocable Transfer Agent Instructions
Exhibit I      -   Form of Legal Opinion
Exhibit J      -   Form of Current Report on 8-K

<PAGE>

                          SECURITIES PURCHASE AGREEMENT

      SECURITIES PURCHASE AGREEMENT (the "Agreement"), dated as of October 29,
2003, by and among Hemispherx Biopharma, Inc., a Delaware corporation, with
headquarters located at One Penn Center, 1617 JFK Boulevard, Suite 660,
Philadelphia, Pennsylvania 19103 (the "Company"), and the investors listed on
the Schedule of Buyers attached hereto (individually, a "Buyer" and
collectively, the "Buyers").

                                    WHEREAS:

      A. The Company and the Buyers are executing and delivering this Agreement
in reliance upon the exemption from securities registration afforded by Rule 506
of Regulation D ("Regulation D") as promulgated by the United States Securities
and Exchange Commission (the "SEC") under the Securities Act of 1933, as amended
(the "1933 Act").

      B. The Company has authorized the issuance of $4,142,357 principal amount
of its 6% Senior Secured Convertible Debentures due October 31, 2005
(collectively, the "Debentures"), which shall be convertible into shares of the
Company's common stock, par value $0.001 per share (the "Common Stock") (as
converted, the "Conversion Shares"), in accordance with the terms of the
Debentures.

      C. The Buyers severally wish to purchase, upon the terms and conditions
stated in this Agreement, (i) the Debentures on the Closing Date (as defined
below), such Debentures to be in the form attached hereto as Exhibit A, in the
respective amounts set forth opposite each Buyer's name on the Schedule of
Buyers for the purchase price opposite such Buyer's name on the Schedule of
Buyers and (ii) warrants (the "Warrants") to purchase shares of Common Stock (as
exercised collectively, the "Warrant Shares"), such Warrants to be substantially
in the form attached hereto as Exhibit B, in the respective amounts set forth
opposite each Buyer's name on the Schedule of Buyers.

      D. Contemporaneously with the execution and delivery of this Agreement,
the parties hereto are executing and delivering a Registration Rights Agreement
substantially in the form attached hereto as Exhibit C (the "Registration Rights
Agreement") pursuant to which the Company has agreed to provide the Buyers with
the benefit of certain registration rights under the 1933 Act and the rules and
regulations promulgated thereunder, and applicable state securities laws, on the
terms and subject to the conditions set forth therein.

      E. The location of defined terms in this Agreement is set forth on the
Index of Terms attached hereto.

      NOW THEREFORE, the Company and the Buyers hereby agree as follows:

      1. PURCHASE AND SALE OF DEBENTURES AND WARRANTS.

            a. Purchase of Debentures and Warrants. Subject to the satisfaction
(or waiver) of the conditions set forth in Sections 6 and 7 below, the Company
shall issue and sell to

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each Buyer, and each Buyer severally agrees to purchase from the Company, the
respective principal amount of Debentures, together with the related Warrants,
for the purchase price set forth opposite such Buyer's name on the Schedule of
Buyers (the "Closing").

            b. The Closing. The date and time of the Closing (the "Closing
Date") shall be 10:00 a.m., New York City time, on the date hereof (or such
later date as is mutually agreed to by the Company and the applicable Buyer or
Buyers) subject to the satisfaction (or waiver) of the conditions set forth in
Sections 6 and 7. The Closing shall occur on the Closing Date at the offices of
Schulte Roth & Zabel LLP, 919 Third Avenue, New York, New York 10022. "Business
Day" means any day other than Saturday, Sunday or other day on which commercial
banks in The City of New York are authorized or required by law to remain
closed.

            c. Delivery and Payment. (i) On the Closing Date, the Company shall
deliver to each Buyer Debentures (in the denominations as such Buyer shall
reasonably request) representing the principal amount of Debentures which such
Buyer is purchasing hereunder, along, with warrants representing the related
Warrants, duly executed on behalf of the Company and registered in the name of
such Buyer.

            (ii) On the Closing Date, each Buyer shall set aside in a separate
segregated account (the "Segregated Account") an amount equal to such Buyer's
total purchase price for such Buyer's portion of Debentures and Warrants as set
forth on the Schedule of Buyers (such "Buyer's Purchase Price").

            (iii) Payment of such Buyer's Purchase Price shall be made by wire
transfer of immediately available funds from such Buyer's Segregated Account in
accordance with the Company's written wire instructions, less any amount
withheld at the Closing for expenses pursuant to Section 4(k) in the following
manner:

                        (A) On the Closing Date, each Buyer shall pay the amount
            set forth opposite such Buyer's name on the Schedule of Buyers under
            the heading "First Payment Amount."

                        (B) Provided that no Default or Event of Default (each
            as defined in the Debentures), or event that with notice or lapse of
            time would constitute a Default or Event of Default, has occurred
            and is continuing on the third Business Day after satisfaction of
            the covenant set forth in Section 4(t) below, each Buyer shall pay
            the amount set forth opposite such Buyer's name on the Schedule of
            Buyer's under the heading "Second Payment Amount."

      The dates of the payments pursuant to the foregoing clauses (A) and (B)
are referred to herein as a "Payment Date".

      2. BUYER'S REPRESENTATIONS AND WARRANTIES.

            Each Buyer represents and warrants with respect to only itself that:

            a. Investment Purpose. Such Buyer (i) is acquiring the Debentures
and the Warrants, (ii) upon conversion of the Debentures owned by it, will
acquire the Conversion

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Shares then issuable, (iii) upon issuance, will acquire the Interest Shares and
Repayment Shares, if any (each as defined in the Debentures), and (iv) upon
exercise of the Warrants held by it, will acquire the Warrant Shares issuable
upon exercise thereof (the Debentures, the Conversion Shares, the Interest
Shares, the Repayment Shares, the Warrants and the Warrant Shares collectively
are referred to herein as the "Securities") for its own account for investment
only and not with a view towards, or for resale in connection with, the public
sale or distribution thereof, except pursuant to sales registered or exempted
under the 1933 Act; provided, however, that by making the representations
herein, such Buyer does not agree to hold any of the Securities for any minimum
or other specific term and reserves the right to dispose of the Securities at
any time, provided further, however, that such disposition shall be in
accordance with or pursuant to a registration statement or an exemption under
the 1933 Act.

            b. Accredited Investor Status. Such Buyer is an "accredited
investor" as that term is defined in Rule 501(a)(3) of Regulation D under the
1933 Act and was not organized for the specific purpose of acquiring the
Securities.

            c. Reliance on Exemptions. Such Buyer understands that the
Securities are being offered and sold to it in reliance on specific exemptions
from the registration requirements of the United States federal and state
securities laws and that the Company is relying upon the truth and accuracy of,
and such Buyer's compliance with, the representations, warranties, agreements,
acknowledgments and understandings of such Buyer set forth herein and in the
applicable Debenture or Warrant in order to determine the availability of such
exemptions and the eligibility of such Buyer to acquire the Securities.

            d. Information. Such Buyer (i) has been furnished with or has had
full access to all of the information that it considers necessary or appropriate
to make an informed investment decision with respect to the Debentures, the
Warrants, the Conversion Shares and the Warrant Shares and that it has requested
from the Company, (ii) has had an opportunity to discuss with management of the
Company the business and financial affairs of the Company and to obtain
information (to the extent the Company possessed such information or could
acquire it without unreasonable effort or expense) necessary to verify any
information furnished to it or to which it had access, (iii) can bear the
economic risk of a total loss of its investment in the Debentures and the
Warrants and (iv) has such knowledge and experience in business and financial
matters so as to enable it to understand the risks of and form an investment
decision with respect to its investment in the Debentures, the Warrants, the
Conversion Shares and the Warrant Shares and to protect its interest in
connection with such investment. Neither such inquiries nor any other due
diligence investigations conducted by such Buyer or its advisors, if any, or its
representatives shall modify, amend or affect such Buyer's right to rely on the
Company's representations and warranties contained in this Agreement.

            e. No Governmental Review. Such Buyer understands that no United
States federal or state agency or any other government or governmental agency
has passed on or made any recommendation or endorsement of the Securities or the
fairness or suitability of the investment in the Securities nor have such
authorities passed upon or endorsed the merits of the offering of the
Securities.

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<PAGE>

            f. Transfer or Resale. Such Buyer understands that except as
provided in the Registration Rights Agreement: (i) the Securities have not been
and are not being registered under the 1933 Act or any state securities laws,
and may not be offered for sale, sold, assigned or transferred unless (A)
subsequently registered thereunder, or (B) such Buyer shall have delivered to
the Company an opinion of counsel in a form reasonably satisfactory to the
Company, to the effect that such Securities to be sold, assigned or transferred
may be sold, assigned or transferred pursuant to an exemption from such
registration, (ii) any sale of the Securities made in reliance on Rule 144
promulgated under the 1933 Act (or a successor rule thereto) ("Rule 144") may be
made only in accordance with the terms of Rule 144 and further, if Rule 144 is
not applicable, any resale of the Securities under circumstances in which the
seller (or the person through whom the sale is made) may be deemed to be an
underwriter (as that term is defined in the 1933 Act) may require compliance
with some other exemption under the 1933 Act or the rules and regulations of the
SEC thereunder; and (iii) neither the Company nor any other person is under any
obligation to register the Securities under the 1933 Act or any state securities
laws or to comply with the terms and conditions of any exemption thereunder. The
Securities may be pledged in connection with a bona fide margin account or other
loan secured by the Securities and such pledge of Securities shall not be deemed
to be a transfer, sale or assignment of the Securities and no Investor effecting
a pledge of Securities shall be required to provide the Company with any notice
thereof or otherwise make any delivery to the Company pursuant to this Agreement
or any other Transaction Document, including, without limitation, this Section
2(f); provided that in order to make any sale, transfer or assignment of
Securities, such Investor and its pledgee makes such disposition in accordance
with or pursuant to a registration statement or an exemption under the 1933 Act.

            g. Legends. Such Buyer understands that the Debentures and Warrants,
except as set forth below, shall bear a restrictive legend and that the
Debentures shall bear a tax legend in substantially the following forms (and a
stop-transfer order may be placed against transfer of such Debentures and
Warrants):

            THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN
            REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED,
            OR APPLICABLE STATE SECURITIES LAWS. THE SECURITIES MAY
            NOT BE OFFERED FOR SALE, SOLD, TRANSFERRED OR ASSIGNED
            IN THE ABSENCE OF (A) AN EFFECTIVE REGISTRATION
            STATEMENT FOR THE SECURITIES UNDER THE SECURITIES ACT OF
            1933, AS AMENDED, OR APPLICABLE STATE SECURITIES LAWS OR
            (B) AN OPINION OF COUNSEL, REASONABLY SATISFACTORY TO
            THE COMPANY, THAT REGISTRATION IS NOT REQUIRED UNDER
            SAID ACT OR APPLICABLE STATE SECURITIES LAWS. THE
            SECURITIES MAY BE PLEDGED IN CONNECTION WITH A BONA FIDE
            MARGIN ACCOUNT OR OTHER LOAN SECURED BY THE SECURITIES.

                                       4
<PAGE>

            THE FOLLOWING INFORMATION IS PROVIDED SOLELY FOR
            PURPOSES OF APPLYING THE U.S. FEDERAL INCOME TAX
            ORIGINAL ISSUE DISCOUNT ("OID") RULES TO THIS DEBENTURE.
            THIS DEBENTURE HAS AN ISSUE PRICE OF $3,550,000, AN
            AGGREGATE AMOUNT OF OID OF $592,357, AN ISSUE DATE OF
            OCTOBER 29, 2003 AND A YIELD TO MATURITY OF 14.33%.

      Such Buyer further understands that until such time as the Conversion
Shares, the Interest Shares, the Repayment Shares and the Warrant Shares have
been sold pursuant to the registration statement contemplated by the
Registration Rights Agreement, the stock certificates representing the
Conversion Shares, the Interest Shares, the Repayment Shares and the Warrant
Shares, except as set forth below, shall bear a restrictive legend in
substantially the following form (and a stop-transfer order may be placed
against transfer of such stock certificates):

            THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT
            BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
            AMENDED. THEY MAY NOT BE OFFERED OR TRANSFERRED BY SALE,
            ASSIGNMENT, PLEDGE OR OTHERWISE UNLESS (I) A
            REGISTRATION STATEMENT FOR THE SECURITIES UNDER THE ACT
            IS IN EFFECT OR (II) THE COMPANY HAS RECEIVED AN OPINION
            OF COUNSEL, WHICH IS SATISFACTORY TO THE COMPANY, TO THE
            EFFECT THAT SUCH REGISTRATION IS NOT REQUIRED UNDER THE
            ACT. THE SECURITIES MAY BE PLEDGED IN CONNECTION WITH A
            BONA FIDE MARGIN ACCOUNT OR OTHER LOAN SECURED BY THE
            SECURITIES.

The legends set forth above, other than the tax legend, shall be removed and the
Company shall issue the relevant securities without such legend to the holder of
the Securities upon which it is stamped, if, (i) such Securities are registered
for resale under the 1933 Act and are transferred or sold pursuant to such
registration or (ii) in connection with a sale transaction, such holder provides
the Company with an opinion of counsel, reasonably satisfactory to the Company,
to the effect that a public sale, assignment or transfer of the Securities may
be made without registration under the 1933 Act.

            h. Authorization; Enforcement; Validity. This Agreement and the
Registration Rights Agreement have been duly and validly authorized, executed
and delivered on behalf of such Buyer and are valid and binding agreements of
such Buyer enforceable against such Buyer in accordance with their terms,
subject as to enforceability to general principles of equity and to applicable
bankruptcy, insolvency, reorganization, moratorium, liquidation and other
similar laws relating to, or affecting generally, the enforcement of applicable
creditors' rights and remedies.

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<PAGE>

            i. Residency. Such Buyer is a resident of that country or state
specified in its address on the Schedule of Buyers.

            j. No Conflicts The execution and performance of this Agreement and
the Registration Rights Agreement do not conflict with any agreement to which
such Buyer is a party or is bound thereby, any court order or judgment addressed
to such Buyer, or the constituent documents of such Buyer.

      3. REPRESENTATIONS AND WARRANTIES OF THE COMPANY.

      The Company represents and warrants to each of the Buyers that as of the
date hereof, except as expressly set forth on the Schedule of Exceptions
attached hereto:

            a. Organization and Qualification. The Company and its
"Subsidiaries" (which for purposes of this Agreement means any entity in which
the Company, directly or indirectly, owns 30% or more of the capital stock or
other equity or similar interests or owns capital stock or holds an equity or
similar interest which ownership entitles the Company to elect 30% or more of
the board of directors or similar governing body of such entity) are
corporations, partnerships or limited liability companies duly organized and
validly existing in good standing (to the extent such concepts are applicable)
under the laws of the jurisdiction in which they are incorporated or organized,
and have the requisite corporate, limited liability company or partnership power
and authorization to own their properties and to carry on their business as now
being conducted. Each of the Company and its Subsidiaries is duly qualified as a
foreign corporation, partnership or limited liability company to do business and
is in good standing (to the extent such concepts are applicable) in every
jurisdiction in which its ownership of property or the nature of the business
conducted by it makes such qualification necessary, except to the extent that
the failure to be so qualified or be in good standing would not have a Material
Adverse Effect. As used in this Agreement, "Material Adverse Effect"means any
material adverse effect on the business, properties, assets, operations, results
of operations, prospects or condition (financial or otherwise) of the Company
and its Subsidiaries, taken as a whole, or on the transactions contemplated
hereby or by the agreements and instruments to be entered into in connection
herewith, or on the authority or ability of the Company to perform its
obligations under the Transaction Documents (as defined below). A complete list
of Subsidiaries is set forth on Schedule 3(a).

            b. Authorization; Enforcement; Validity. The Company has the
requisite corporate power and authority to enter into and perform its
obligations under this Agreement, the Debentures, the Warrants, the Registration
Rights Agreement, the Irrevocable Transfer Agent Instructions, the Security
Agreement, the Collateral Agency Agreement, dated as of the date hereof, among
the Buyers and acknowledged by the Company, the Account Control Agreement, the
Mortgages, each deposit account control agreement and security account control
agreement entered into among, or amended among, the Company, the Agent (as
defined) and the depositary bank named therein (collectively, the "Bank
Agreements") and each of the other agreements entered into by the parties hereto
in connection with the transactions contemplated by this Agreement
(collectively, the "Transaction Documents"), and to issue the Securities in
accordance with the terms hereof and thereof. The execution and delivery of the
Transaction Documents by the Company and the consummation by it of the
transactions contemplated hereby and thereby,

                                       6
<PAGE>

including, without limitation, the issuance of the Debentures, the reservation
for issuance and the issuance of the Conversion Shares issuable upon conversion
thereof, the reservation for issuance and the issuance of Interest Shares and
Repayment Shares in accordance with the terms of the Debentures, the issuance of
the Warrants and the reservation for issuance and the issuance of the Warrant
Shares issuable upon exercise of the Warrants, have been duly authorized by the
Company's Board of Directors and no further consent or authorization is required
of the Company's Board of Directors or stockholders (except to the extent that
stockholder approval may be required pursuant to the rules of the AMEX for the
issuance of a number of Conversion Shares, Interest Shares, Repayment Shares and
Warrant Shares greater in the aggregate than 19.99% of the number of shares of
Common Stock outstanding immediately prior to the Closing Date (the "19.99%
Rule")). The Transaction Documents executed on the date hereof have been and the
other Transaction Documents when executed by the Company in accordance with
their terms will be duly executed and delivered by the Company and constitute
and will constitute the valid and binding obligations of the Company enforceable
against the Company in accordance with their terms, except as such
enforceability may be limited by general principles of equity or applicable
bankruptcy, insolvency, reorganization, moratorium, liquidation or similar laws
relating to, or affecting generally, the enforcement of creditors' rights and
remedies.

            c. Capitalization. As of October 29, 2003, the authorized capital
stock of the Company consists of 100,000,000 shares of Common Stock, of which as
of such date, 37,658,733 shares are issued and outstanding and 16,400,100 shares
are reserved for issuance pursuant to the Company's stock option purchase plans
(including pursuant to options outstanding as of such date as well as options
granted thereafter), outstanding stock warrants and convertible debentures. All
of such outstanding shares have been, or upon issuance will be, validly issued
and are fully paid and nonassessable. Except as disclosed in Schedule 3(c) or in
the SEC Documents, (A) no shares of the Company's capital stock are subject to
preemptive rights or any other similar rights (arising under Delaware law, the
Company's Certificate of Incorporation or By-laws or any agreement or instrument
to which the Company is a party) or any liens or encumbrances granted or created
by the Company; (B) there are no outstanding options, warrants, scrip, rights to
subscribe to, calls or commitments of any character whatsoever relating to, or
securities or rights convertible into, any shares of capital stock of the
Company or any of its Subsidiaries, or contracts, commitments, understandings or
arrangements by which the Company or any of its Subsidiaries is or may become
bound to issue additional shares of capital stock of the Company or any of its
Subsidiaries or options, warrants, scrip, rights to subscribe to, calls or
commitments of any character whatsoever relating to, or securities or rights
convertible into, any shares of capital stock of the Company or any of its
Subsidiaries (other than any such options, warrants, scrip, rights, calls,
commitments, securities, understandings and arrangement outstanding under plans
disclosed in the SEC Documents); (C) there are no outstanding debt securities,
notes, credit agreements, credit facilities or other agreements, documents or
instruments evidencing indebtedness of the Company or any of its Subsidiaries or
by which the Company or any of its Subsidiaries is or may become bound; (D)
there are no amounts outstanding under, and there will be no amounts due upon
termination of, any credit agreement or credit facility; (E) there are no
financing statements securing obligations in any amounts greater than $100,000,
singly, or $250,000 in the aggregate, filed in connection with the Company or
any of its Subsidiaries; (F) there are no agreements or arrangements under which
the Company or any of its Subsidiaries is obligated to register the sale of any
of their securities under the 1933 Act (except the Registration Rights
Agreement); (G) there are no outstanding

                                       7
<PAGE>

securities or instruments of the Company or any of its Subsidiaries which
contain any redemption or similar provisions, and there are no contracts,
commitments, understandings or arrangements by which the Company or any of its
Subsidiaries is or may become bound to redeem a security of the Company or any
of its Subsidiaries; (H) there are no securities or instruments containing
anti-dilution or similar provisions that will be triggered by the issuance of
the Securities as described in this Agreement; (I) the Company does not have any
stock appreciation rights or "phantom" stock plans or agreements or any similar
plan or agreement; (J) to the Company's knowledge, (i) no current or former
officer or director who individually owns 1% or more of the Company's
outstanding capital stock or (ii) other beneficial owner of 5% or more of the
Company's outstanding capital stock, has pledged shares of the Company's capital
stock in connection with a margin account or other loan secured by such capital
stock; and (K) the Company and its Subsidiaries have no liabilities or
obligations required to be disclosed in the SEC Documents (as defined herein)
but not so disclosed in the SEC Documents, other than those incurred in the
ordinary course of the Company's or its Subsidiaries' respective businesses and
which, individually or in the aggregate, do not or would not have a Material
Adverse Effect on the Company and its Subsidiaries taken as a whole. The Company
has made available to each Buyer that has requested it true and correct copies
of the Company's Certificate of Incorporation, as amended and as in effect on
the date hereof (the "Certificate of Incorporation"), and the Company's By-laws,
as amended and as in effect on the date hereof (the "By-laws"), and the terms of
all securities convertible into or exercisable or exchangeable for Common Stock
and the material rights of the holders thereof in respect thereto except for
stock options granted under any benefit plan or stock option plan of the Company
approved by the Board of Directors of the Company.

            d. Issuance of Securities. The Securities are duly authorized and,
upon issuance in accordance with the terms of the applicable Transaction
Documents, shall be (i) validly issued, fully paid and non-assessable and (ii)
free from all taxes, liens and charges with respect to the issuance thereof
(other than any such taxes, liens and charges created by any Buyer or assignee
or transferee), and, except as set forth in Schedule 3(c), shall not be subject
to pre-emptive rights or other similar rights of shareholders of the Company. As
of the Closing, at least 3,654,297 shares of Common Stock (subject to adjustment
pursuant to the Company's covenant set forth in Section 4(f) below) will have
been duly authorized and reserved for issuance upon conversion of the
Debentures, exercise of the Warrants and the issuance of the Interest Shares and
the Repayment Shares issuable over the full term of the Debentures (assuming the
Company paid the maximum amount of interest permitted to be paid in Interest
Shares over the full term of the Debentures). Upon conversion or issuance in
accordance with the Debentures or the Warrants, as applicable, the Conversion
Shares, the Interest Shares, the Repayment Shares and the Warrant Shares, as the
case may be, will be validly issued, fully paid and non-assessable and free from
all taxes, liens and charges with respect to the issue thereof (other than any
such taxes, liens and charges created by any Buyer or any assignee or
transferee), with the holders being entitled to all rights accorded to a holder
of Common Stock. Based, in part, on reliance on the representations and
warranties of each of the Buyers in the Transaction Documents, the issuance by
the Company of the Securities is exempt from registration under the 1933 Act.

            e. No Conflicts. The execution, delivery and performance of the
Transaction Documents by the Company and the consummation by the Company of the
transactions contemplated hereby and thereby (including, without limitation, the
reservation for

                                       8
<PAGE>

issuance and issuance of the Conversion Shares, the Interest Shares, the
Repayment Shares and the Warrant Shares) will not (i) result in a violation of
the Certificate of Incorporation or the By-laws; (ii) conflict with, or
constitute a default (or an event which with notice or lapse of time or both
would become a default) under, or give to others any rights of termination,
amendment, acceleration or cancellation of, any material agreement, indenture or
instrument to which the Company or any of its Subsidiaries is a party (except
for such conflicts, defaults, terminations, amendments, accelerations,
cancellations and violations as would not, individually or in the aggregate,
reasonably be expected to result in a Material Adverse Effect); or (iii) result
in a violation of any law, rule, regulation, order, judgment or decree
(including federal and state securities laws and regulations and the rules and
regulations of the Principal Market (as defined below)) applicable to the
Company or any of its Subsidiaries or by which any property or asset of the
Company or any of its Subsidiaries is bound or affected. Neither the Company nor
its Subsidiaries is in violation of any term of or in default under its
Certificate of Incorporation, By-laws or their organizational charter or
by-laws, respectively. Neither the Company nor any of its Subsidiaries is in
violation of any term of or in default under any contract, agreement, mortgage,
indebtedness, indenture, instrument, judgment, decree or order or any statute,
rule or regulation applicable to the Company or its Subsidiaries, except where
such violations and defaults would not result, either individually or in the
aggregate, in a Material Adverse Effect. The business of the Company and its
Subsidiaries is not being conducted in violation of any law, ordinance or
regulation of any governmental entity, except where such violations would not
result, either individually or in the aggregate, in a Material Adverse Effect.
Except as specifically contemplated by this Agreement, as required under the
1933 Act, as required by Blue Sky filings or as required by the 19.99% Rule, the
Company is not required to obtain any consent, authorization or order of, or
make any filing or registration with, any court or governmental agency or any
regulatory or self-regulatory agency in order for it to execute, deliver or
perform any of its obligations under or contemplated by the Transaction
Documents. Except as disclosed in Schedule 3(e), all consents, authorizations,
orders, filings and registrations which the Company is required to obtain
pursuant to the preceding sentence have been obtained or effected on or prior to
the date hereof. The Company and its Subsidiaries are currently unaware of any
facts or circumstances which might give rise to any of the foregoing events set
forth in this paragraph. The Company is not in violation of the listing
requirements of the Principal Market, and has no actual knowledge of any facts
which would reasonably lead to delisting or suspension of the Common Stock by
the Principal Market in the foreseeable future. Notwithstanding anything herein
to the contrary, the Company's listing application with respect to shares of
Common Stock underlying the March Securities, June Securities and July
Securities have been filed with the Principal Market but have not been finally
approved by the Principal Market. The Company believes, but cannot assure, that
such listing applications will be finally approved by the Principal Market.

            f. SEC Documents; Financial Statements. Since January 1, 2001, other
than a Form 8-K/A with respect to the transactions contemplated by the
Interferon Asset Agreement, the Company has filed all reports, schedules, forms,
statements and other documents required to be filed by it with the SEC pursuant
to the reporting requirements of the Securities Exchange Act of 1934, as amended
(the "1934 Act") (all of the foregoing filed prior to or on the date hereof and
all exhibits included therein and financial statements and schedules thereto and
documents incorporated by reference therein being hereinafter referred to as the
"SEC Documents"). As of the date of filing of such SEC Documents, each such SEC
Document, as it

                                       9
<PAGE>

may have been subsequently amended by filings made by the Company with the SEC
prior to the date hereof, complied in all material respects with the
requirements of the 1934 Act and the rules and regulations of the SEC
promulgated thereunder applicable to such SEC Document. None of the SEC
Documents, as of the date filed and as they may have been subsequently amended
by filings made by the Company with the SEC prior to the date hereof, contained
any untrue statement of a material fact or omitted to state a material fact
required to be stated therein or necessary in order to make the statements
therein, in the light of the circumstances under which they were made, not
misleading. As of their respective dates, the financial statements of the
Company included in the SEC Documents complied as to form in all material
respects with applicable accounting requirements and published rules and
regulations of the SEC with respect thereto. Such financial statements have been
prepared in accordance with generally accepted accounting principles,
consistently applied, during the periods involved (except (i) as may be
otherwise indicated in such financial statements or the notes thereto, or (ii)
in the case of unaudited interim statements, to the extent they may exclude
footnotes or may be condensed or summary statements) and fairly present in all
material respects the financial position of the Company as of the dates thereof
and the results of its operations and cash flows for the periods then ended
(subject, in the case of unaudited statements, to normal year-end audit
adjustments). The Company is not aware of any fact or circumstance that would
result or reasonably be likely to result in the Company receiving a "going
concern" opinion or qualification from its independent auditor's with respect to
the Company's financial position for the year ended December 31, 2002. To the
best of the Company's knowledge, no other written information provided by or on
behalf of the Company to the Buyers which is not included in the SEC Documents,
including, without limitation, information referred to in Section 2(d), contains
any untrue statement of a material fact or omits to state any material fact
necessary in order to make the statements therein, in the light of the
circumstances under which they are or were made, not misleading. Neither the
Company nor any of its Subsidiaries nor any of their officers, directors,
employees or agents have provided the Buyers with any material, nonpublic
information. As of the date hereof, other than the need to file updated
financial statements in the Company's Annual Report on Form 10-K for the year
ended December 31, 2002, the Company meets the requirements for use of Form S-1
for registration of the resale of Registrable Securities (as defined in the
Registration Rights Agreement) and does not have any knowledge or reason to
believe that it does not meet such requirements or any actual knowledge of any
fact which would reasonably result in its not meeting such requirements. As of
the date hereof, the Company does not meet the requirements for use of Form S-3
for registration of the resale of Registrable Securities. The Company is not
required to file and will not be required to file any agreement, note, lease,
mortgage, deed or other instrument entered into prior to the date hereof and to
which the Company is a party or by which the Company is bound which has not been
previously filed as an exhibit to its reports filed with the SEC under the 1934
Act. Except for the issuance of the Debentures and the Warrants contemplated by
this Agreement and the transactions contemplated therein, no event, liability,
development or circumstance has occurred or exists, or is currently contemplated
to occur, with respect to the Company or its Subsidiaries or their respective
business, properties, operations or financial condition, that would be required
to be disclosed by the Company under applicable securities laws and which has
not been publicly disclosed.

            g. Absence of Certain Changes. Except as disclosed in the SEC
Documents available on the EDGAR system, there has been no change or development
that has had or could reasonably be expected to have, either individually or in
the aggregate, a Material

                                       10
<PAGE>

Adverse Effect. The Company has not taken any steps, and does not currently
expect to take any steps, to seek protection pursuant to any bankruptcy law nor
does the Company or any of its Subsidiaries have any knowledge or reason to
believe that its creditors intend to initiate involuntary bankruptcy proceedings
or any actual knowledge of any fact which would reasonably lead a creditor to do
so. Except as disclosed in the SEC Documents available on the EDGAR system,
since December 31, 2000, (i) the Company has not declared or paid any dividends,
and (ii) as of the date hereof, has not sold any assets, individually or in the
aggregate, in excess of $100,000 outside of the ordinary course of business or
had capital expenditures, individually or in the aggregate, in excess of
$200,000.

            h. Absence of Litigation. Except as disclosed in the section titled
"Legal Proceedings" in (i) the Company's Annual Report on Form 10-K for the year
ended December 31, 2002 or (ii) any of the Company's SEC Documents filed since
the filing of such Form 10-K, there is no action, suit, proceeding, inquiry or
investigation before or by any court, public board, government agency,
self-regulatory organization or body pending or, to the knowledge of the Company
or any of its Subsidiaries, threatened in writing against the Company or any of
the Company's Subsidiaries or any of the Company's or the Company's
Subsidiaries' officers or directors in their capacities as such, that would
reasonably be expected to result in judgments against the Company or any of its
Subsidiaries in an amount, individually or in the aggregate, in excess of
$250,000.

            i. No Integrated Offering. Neither the Company, nor any of its
affiliates, nor any person acting on its or their behalf has, directly or
indirectly, made any offers or sales of any security or solicited any offers to
buy any security, under circumstances that would cause this offering of the
Securities to be integrated with prior offerings by the Company for purposes of
the 1933 Act or any applicable stockholder approval provisions, including,
without limitation, under the rules and regulations of any exchange or automated
quotation system on which any of the securities of the Company are listed or
designated, nor will the Company or any of its Subsidiaries take any action or
steps that would cause the offering of the Securities to be integrated with
other offerings.

            j. Employment Matters; ERISA Matters. (i) Neither the Company nor
any of its Subsidiaries is involved in any material union labor dispute nor, to
the knowledge of the Company or any of its Subsidiaries, is any such dispute
threatened. None of the Company's or its Subsidiaries' U.S. employees is a
member of a union which relates to such employee's relationship with the
Company. Neither the Company nor any of its Subsidiaries is a party to a
collective bargaining agreement. No executive officer (as defined in Rule 501(f)
of the 1933 Act) has notified the Company in writing that such officer intends
to leave the Company or otherwise terminate such officer's employment with the
Company.

                  (ii) The Company and its Subsidiaries are in compliance with
all federal, state, local and foreign laws and regulations respecting employment
and employment practices, terms and conditions of employment and wages and
hours, except where failure to be in compliance would not, either individually
or in the aggregate, reasonably be expected to result in a Material Adverse
Effect.

                                       11
<PAGE>

            k. Intellectual Property Rights. The Company and its Subsidiaries
own or possess adequate rights or licenses to use (i) all trademarks, trade
names, trade dress, service marks, service mark registrations, service names,
patents, patent rights, copyrights, inventions, technology licenses, approvals,
governmental authorizations, trade secrets, and other intellectual property
rights (collectively, "Intellectual Property") necessary to conduct their
respective businesses as now conducted and as currently contemplated to be
conducted other than businesses that the Company has not as of the date hereof
launched, except where the failure to own, possess or protect such rights would
not, either individually or in the aggregate, reasonably be expected to result
in a Material Adverse Effect. None of the Company's or its Subsidiaries'
Intellectual Property rights have expired or terminated, or are expected to
expire or terminate within two years from the date of this Agreement, except
where such expiration or termination would not, either individually or in the
aggregate, reasonably be expected to result in a Material Adverse Effect. Except
as would not reasonably be expected to result in a Material Adverse Effect, the
Company and its Subsidiaries do not have any knowledge of any infringement by
the Company or its Subsidiaries of Intellectual Property rights of others, or of
any development of similar or identical trade secrets or technical information
by others and except as would not reasonably be expected to result in a Material
Adverse Effect, there is no claim, action or proceeding being made by or brought
against, or to the knowledge of the Company, currently threatened in writing by
or against, the Company or its Subsidiaries regarding the Intellectual Property
rights of or the use of any Intellectual Property by the Company or its
Subsidiaries or any third party. The Company and its Subsidiaries have taken all
reasonable security measures to protect the secrecy, confidentiality and value
of all of their Intellectual Property.

            l. Title. The Company and its Subsidiaries have good and marketable
title in fee simple to all real property and good and marketable title to all
personal property owned by them which is material to the business of the Company
and its Subsidiaries taken as a whole, in each case free and clear of all liens,
encumbrances and defects except such as (i) constitute purchase money security
interests, (ii) are described in Schedule 3(l) or (iii) such as do not
materially affect the value of such property and do not materially interfere
with the use made and proposed to be made of such property by the Company and
any of its Subsidiaries. Any real property and facilities held under lease by
the Company and any of its Subsidiaries are held by them under valid, subsisting
and enforceable leases with such exceptions as are not material and do not
interfere with the use made and proposed to be made of such property and
facilities by the Company and its Subsidiaries.

            m. Environmental Laws. The Company and its Subsidiaries (A) are in
compliance with any and all Environmental Laws, (B) have received all permits,
licenses or other approvals required of them under applicable Environmental Laws
to conduct their respective businesses, and (C) are in compliance with all terms
and conditions of any such permit, license or approval, except in each case
where the failure of the Company and its Subsidiaries would not, either
individually or in the aggregate, reasonably be expected to result in a Material
Adverse Effect. The term "Environmental Laws" means all federal, state, local or
foreign laws relating to pollution or protection of human health or the
environment (including, without limitation, ambient air, surface water,
groundwater, land surface or subsurface strata), including, without limitation,
laws relating to emissions, discharges, releases or threatened releases of
chemicals, pollutants, contaminants, or toxic or hazardous substances or wastes
(collectively, "Hazardous Materials") into the environment, or otherwise
relating to the

                                       12
<PAGE>

manufacture, processing, distribution, use, treatment, storage, disposal,
transport or handling of Hazardous Materials, as well as all authorizations,
codes, decrees, demands or demand letters, injunctions, judgments, licenses,
notices or notice letters, orders, permits, plans or regulations issued,
entered, promulgated or approved thereunder.

            n. Insurance. The Company and each of its Subsidiaries are insured
by insurers of recognized financial responsibility against such losses and risks
and in such amounts as management of the Company believes to be prudent and
customary in the businesses in which the Company and its Subsidiaries are
engaged. Except as set forth on Schedule 3(n), neither the Company nor any such
Subsidiary has been refused any insurance coverage sought or applied for and
neither the Company nor any such Subsidiary has any reason to believe that it
will not be able to renew its existing insurance coverage as and when such
coverage expires or to obtain similar coverage from similar insurers as may be
necessary to continue its business at a cost that would not have a Material
Adverse Effect.

            o. Regulatory Permits. Except for Permits (as defined below) the
absence of which would not, either individually or in the aggregate, result in a
Material Adverse Effect, the Company and its Subsidiaries possess all
certificates, authorizations and permits issued by the appropriate federal,
state or foreign regulatory authorities necessary to conduct their respective
businesses as currently conducted (the "Permits"), and neither the Company nor
any such Subsidiary has received any written notice of proceedings relating to
the revocation or modification of any such Permit.

            p. No Materially Adverse Contracts, Etc. Neither the Company nor any
of its Subsidiaries is subject to any charter, corporate or other legal
restriction, or any judgment, decree, order, rule or regulation which in the
judgment of the Company's officers has or is currently expected in the future to
have a Material Adverse Effect. Neither the Company nor any of its Subsidiaries
is a party to any contract or agreement which in the judgment of the Company's
officers has or is currently expected to have a Material Adverse Effect.

            q. Tax Status. Except as could not reasonably be expected to have a
Material Adverse Effect, the Company and each of its Subsidiaries (i) has made
or filed all federal and state income and all other tax returns, reports and
declarations required by any jurisdiction to which it is subject, (ii) has paid
all taxes and other governmental assessments and charges due with respect to the
periods covered by such returns, reports and declarations, except those being
contested in good faith and for which the Company has made appropriate reserves
on its books, and (iii) has paid or set aside on its books provisions reasonably
adequate for the payment of all taxes for periods subsequent to the periods to
which such returns, reports or declarations (referred to in clause (i) above)
apply. There are no unpaid taxes that are individually or in the aggregate
material in amount claimed to be due by the taxing authority of any
jurisdiction, and the officers of the Company know of no basis for any such
claim.

            r. Transactions With Affiliates. Except as set forth on Schedule
3(r) and in the SEC Documents, and other than the grant of stock options
described on Schedule 3(c), none of the officers, directors, employees of the
Company is presently a party to any transaction with the Company or any of its
Subsidiaries (other than in connection with the provision of services as
employees, officers and directors, payment of ordinary course business expenses
for

                                       13
<PAGE>

employees, and other expenditures on behalf of employees in an aggregate amount
for all employees not in excess of $500,000), including any contract, agreement
or other arrangement providing for the furnishing of services to or by,
providing for rental of real or personal property to or from, or otherwise
requiring payments to or from any such officer, director or employee or, to the
knowledge of the Company, any corporation, partnership, trust or other entity in
which any such officer, director, or employee has a substantial interest or is
an officer, director, trustee or partner.

            s. Application of Takeover Protections. The Company and its board of
directors have taken all necessary action, if any, in order to render
inapplicable any control share acquisition, business combination, poison pill
(including any distribution under a rights agreement) or other similar
anti-takeover provision under the Certificate of Incorporation, the laws of the
state of its incorporation or the laws of any other state which is or could
become applicable to the Buyers as a result of the transactions contemplated by
this Agreement, including, without limitation, the Company's issuance of the
Securities and the Buyers' ownership of the Securities.

            t. Foreign Corrupt Practices. Neither the Company nor any of its
Subsidiaries, nor any director, officer, agent, employee or other person acting
on behalf of the Company or any Subsidiary has, in the course of his actions
for, or on behalf of, the Company or any Subsidiary used any corporate funds for
any unlawful contribution, gift, entertainment or other unlawful expenses
relating to political activity; made any direct or indirect unlawful payment to
any foreign or domestic government official or employee from corporate funds;
violated or is in violation of any provision of the U.S. Foreign Corrupt
Practices Act of 1977; or made any bribe, rebate, payoff, influence payment,
kickback or other unlawful payment to any foreign or domestic government
official or employee.

      4. COVENANTS.

            a. Best Efforts. Each party shall use its reasonable best efforts to
timely satisfy each of the conditions to be satisfied by it as provided in
Sections 6 and 7 of this Agreement.

            b. Form D and Blue Sky. The Company agrees to file a Form D with
respect to the Securities as required under Regulation D and to provide a copy
thereof to each Buyer promptly after such filing. The Company shall, on or
before each of the Closing Dates, take such action as the Company shall
reasonably determine is necessary in order to obtain an exemption for, or to
qualify the Securities for, sale to the Buyers at each of the Closings pursuant
to this Agreement under applicable securities or "Blue Sky" laws of the states
of the United States (or to obtain an exemption from such qualification), and
shall provide evidence of any such action so taken to the Buyers on or prior to
each of the Closing Dates (to the extent such action is required by applicable
law). The Company shall make all filings and reports relating to the offer and
sale of the Securities required under applicable securities or "Blue Sky" laws
of the states of the United States following each Closing Date.

            c. Reporting Status. Other than pursuant to a Change of Control (as
defined in the Debentures), until the earlier of (i) the date which is one year
after the date as of

                                       14
<PAGE>

which the Investors (as that term is defined in the Registration Rights
Agreement) may sell all of the Conversion Shares, the Interest Shares, the
Repayment Shares and the Warrant Shares without restriction pursuant to Rule
144(k) promulgated under the 1933 Act (or successor thereto) and (ii) the date
on which (A) the Investors shall have sold all the Conversion Shares, the
Interest Shares, the Repayment Shares and the Warrant Shares and (B) none of the
Debentures or Warrants is outstanding (the "Reporting Period"), the Company
shall timely file all reports required to be filed with the SEC pursuant to the
1934 Act and the Company shall not terminate its status as an issuer required to
file reports under the 1934 Act even if the 1934 Act or the rules and
regulations thereunder would otherwise permit such termination.

            d. Use of Proceeds. The Company will use the proceeds from the sale
of the Debentures and the Warrants to fund the acquisition of certain assets of
Seller (as defined Section 4(t)(i) below) and for general corporate purposes.

            e. Financial Information. The Company agrees to send the following
to each Investor during the Reporting Period: (i) within ten (10) days after the
filing thereof with the SEC, a copy of its Annual Reports on Form 10-K, its
Quarterly Reports on Form 10-Q, any Current Reports on Form 8-K and any
registration statements (other than on Form S-8) or amendments thereto filed
pursuant to the 1933 Act, provided that if any such report is filed with the SEC
through EDGAR and is available to the Buyers via EDGAR then no such deliveries
shall be required; (ii) using its reasonable efforts, on the same day as the
release thereof, facsimile copies of all press releases issued by the Company
relating to the Company's quarterly operating results and (iii) copies of any
notices and other information made available or given to the stockholders of the
Company generally, contemporaneously with the making available or giving thereof
to the stockholders.

            f. Reservation of Shares. Prior to the date on which payments have
been made pursuant to Section 25 of the Debentures in an amount equal to the
entire Outstanding Principal Amount (as defined in the Debentures), together
with accrued and unpaid interest on all Debentures outstanding the Company shall
take all action necessary to at all times have authorized, and reserved for the
purpose of issuance, no less than 135% of the number of shares of Common Stock
needed to provide for the issuance of the Conversion Shares upon conversion of
all of the Debentures, the Warrant Shares upon exercise of all of the Warrants
(without regard to any limitations on conversions or exercise) and the maximum
number of Interest Shares issuable over the full term of the Debentures
(assuming the Company paid the maximum amount of interest permitted to be paid
in Interest Shares over the full term of the Debentures), and after such time
100% of the number of shares of Common Stock needed to provide for the issuance
of the Conversion Shares upon conversion of all of the Debentures and of the
Warrant Shares upon exercise of all of the Warrants (without regard to any
limitations on conversions or exercise).

            g. Listing. The Company timely shall satisfy the condition set forth
in clause (2) of Section 7(a)(ii) and also shall promptly secure the listing of
all of the Registrable Securities (as defined in the Registration Rights
Agreement) upon each national securities exchange and automated quotation
system, if any, upon which shares of Common Stock are then listed (subject to
official notice of issuance) and, shall maintain, so long as any other shares of
Common Stock shall be so listed, such listing of all Registrable Securities from
time to time issuable under the terms of the Transaction Documents. So long as
any Securities are

                                       15
<PAGE>

outstanding, the Company shall maintain the Common Stock's authorization for
quotation on listing on The New York Stock Exchange, Inc. (the "NYSE"), the
American Stock Exchange, Inc. ("AMEX") or The Nasdaq Stock Market, Inc.
("NASDAQ") (as applicable, the "Principal Market"). The Company shall pay all
fees and expenses in connection with satisfying its obligations under this
Section 4(g).

            h. Filing of Form 8-K. At or before 8:30 a.m., New York City time,
on the Business Day following the Closing Date, the Company shall file a Current
Report on Form 8-K with the SEC describing the terms of the transactions
contemplated by the Transaction Documents and including as exhibits to such
Current Report on Form 8-K this Agreement, the form of Debenture,. the form of
Warrants and the Registration Rights Agreement in the form required by the 1934
Act (with such exhibits, a "Form 8-K")). At or before 8:30 a.m., New York City
time, on the Business Day following each Payment Date, if any, the Company shall
file a Form 8-K with the SEC describing the transaction consummated on such
Payment Date. From and after the initial filing of the Form 8-K with the SEC,
unless required pursuant to Section 3(h) of the Registration Rights Agreement,
no Buyer shall be in possession of any material, nonpublic information received
from the Company or any of its officers, directors, employees or agents, that is
not disclosed in the Form 8-K. Unless required pursuant to Section 3(h) of the
Registration Rights Agreement, the Company shall not, and shall cause each of
its officers, directors, employees and agents, not to, provide any Buyer with
any material nonpublic information regarding the Company from and after the
filing of the Form 8-K with the SEC without the express written consent of such
Buyer. In the event of a breach of the foregoing covenant by the Company or any
of its or its officers, directors, employees and agents, in addition to any
other remedy provided herein or in the Transaction Documents, a Buyer shall have
the right to make a public disclosure, in the form of a press release, public
advertisement or otherwise, of such material nonpublic information without the
prior approval by the Company or any of its officers, directors, employees or
agents. No Buyer shall have any liability to the Company or any of its officers,
directors, employees, stockholders or agents for any such disclosure. Subject to
the foregoing, neither the Company nor any Buyer shall issue any press releases
or any other public statements with respect to the transactions contemplated
hereby, other than as set forth in Section 9(j) hereof.

            i. Proxy Statement. If the Company at any time determines that in
connection with the issuance of the Securities, Stockholder Approval is required
by the Principal Market in connection with the 19.99% Rule, the Company shall
provide each stockholder entitled to vote at the next meeting of stockholders of
the Company, which meeting shall occur on or before ninety days from the date of
such determination (the "Stockholder Meeting Deadline"), a proxy statement,
which has been previously reviewed by the Buyers and a counsel of their choice,
soliciting each such stockholder's affirmative vote at such stockholder meeting
for approval of the Company's issuance of all of the Securities as described in
the Transaction Documents in accordance with applicable law and the rules and
regulations of the Principal Market (such affirmative approval being referred to
herein as the "Stockholder Approval"), and the Company shall use its reasonable
best efforts to solicit its stockholders' approval of such issuance of the
Securities and to cause the Board of Directors of the Company to recommend to
the stockholders that they approve such proposal.

                                       16
<PAGE>

            j. Pledge of Securities. The Company acknowledges and agrees that
the Securities may be pledged in compliance with applicable securities laws by
an Investor in connection with a bona fide margin agreement or other loan
secured by the Securities. The pledge of Securities shall not be deemed to be a
transfer, sale or assignment of the Securities hereunder, and no Investor
effecting a pledge of Securities shall be required to provide the Company with
any notice thereof or otherwise make any delivery to the Company pursuant to
this Agreement or any other Transaction Document, including, without limitation,
Section 2(f) of this Agreement; provided that in order to make any sale,
transfer or assignment of Securities, such Investor and its pledgee makes such
disposition in accordance with or pursuant to a registration statement or an
exemption under the 1933 Act. The Company hereby agrees to execute and deliver
such reasonable documentation as a pledgee of the Securities may reasonably
request in connection with a pledge of the Securities to such pledgee by an
Investor.

            k. Expenses. Subject to Section 9(l) below, at the Closing, the
Company shall reimburse the Buyers for the Buyers' reasonable, documented fees
and expenses (including legal expenses both in connection with this Agreement
and with prior registration statements filed by the Company) incurred in
connection with the consummation of the transactions contemplated by this
Agreement, up to a maximum of $30,000 (in addition to any other expense amounts
previously paid to the Buyers), which reasonable, documented amount shall be
withheld by the Buyers from its purchase price to be paid at the Closing. In
addition, Portside Growth & Opportunity Fund shall withhold from the amounts set
forth opposite its name on the Schedule of Buyers $140,000 from the First
Payment Amount and $105,000 from the Second Payment Amount, in each case to pay
the fees of the placement agent engaged by the Company in connection with the
transactions contemplated hereby.

            l. Additional Debentures. For so long as any Buyer beneficially owns
any Debentures, the Company shall not issue any other securities that would
cause a breach or default under the Debentures.

            m. Tax Matters.

                        (i) [Reserved.]

                        (ii) The Company shall be permitted to withhold from any
            amounts payable to a Buyer, a Debenture holder, a Warrant holder or
            a holder of Common Stock any taxes required by law to be withheld
            from such amount. If the Company shall be required to withhold or
            deduct any tax, levy or other governmental charge, excluding (A) net
            income taxes, franchise taxes, or taxes imposed on or measured by
            net income (or overall gross receipts, to the extent such tax is
            imposed in lieu of a tax on net income by a jurisdiction that does
            not impose any tax based on or measured by net income) on any Buyer
            or Debenture holder by the jurisdiction in which such Buyer or
            Debenture holder is organized or any other jurisdiction in which
            such Buyer or Debenture holder would be subject to tax without
            regard to the transactions contemplated hereby, and (B) U.S. Federal
            withholding taxes (unless such U.S. Federal withholding taxes would
            not be imposed but for a change in or amendment to the Internal
            Revenue Code of 1986, as amended (the "Code"), the Treasury
            Regulations or any other administrative authority thereunder or any
            tax treaty or the release or promulgation of any judicial

                                       17
<PAGE>

            decision relating thereto, in each case, on or after the later of
            (x) the date of this Agreement or (y) the date such Debenture holder
            becomes a party hereto (each, a "Change in Law")) (all such
            non-excluded taxes, levies or other governmental charges, "Taxes")
            from any payment of interest, or any accrual of original issue
            discount, for U.S. Federal income tax purposes made hereunder or
            under any Debenture to or for the benefit of any Buyer or any
            Debenture holder, then (A) the amount payable shall be increased by
            the amount necessary so that after making all required deductions
            and withholdings (including deductions and withholdings with respect
            to additional amounts payable under this Section 4(m)) such Buyer or
            such Debenture holder shall receive an amount equal to the amount it
            would have received if no such deduction or withholding of Taxes had
            been required, (B) the Company shall make such deduction or
            withholding and (C) the Company shall pay the full amount deducted
            to the appropriate governmental authority in accordance with
            applicable law. If any Buyer or any Debenture holder is organized
            under the laws of a jurisdiction other than the United States, any
            State thereof or the District of Columbia (each a "Non-U.S.
            Debenture Holder"), it shall deliver to the Company two copies of
            either (A) U.S. Internal Revenue Service Form W-8BEN (claiming
            complete exemption from U.S. Federal withholding tax under an income
            tax treaty), or any successor form; (B) U.S. Internal Revenue
            Service Form W-8ECI (claiming complete exemption from U.S. Federal
            withholding tax because the income is effectively connected with a
            U.S. trade or business), or any successor form; (C) in the case of a
            Non-U.S. Debenture Holder claiming exemption from U.S. Federal
            withholding tax under Section 871(h) or 881(c) of the Code, with
            respect to payments of "portfolio interest," U.S. Internal Revenue
            Service Form W-8BEN (certifying as to beneficial ownership), or any
            successor form, and a certificate in form and substance reasonably
            acceptable to the Company representing that such Non-U.S. Debenture
            Holder is not a "bank" for purposes of Section 881(c) of the Code,
            is not a 10-percent shareholder (within the meaning of Section
            871(h)(3)(B) of the Code) of the Company and is not a "controlled
            foreign corporation" related to the Company (within the meaning of
            Section 864(d)(4) of the Code); or (D) other applicable form,
            certificate or document prescribed by the U.S. Internal Revenue
            Service certifying as to such Non-U.S. Debenture Holder's
            entitlement to a complete exemption from U.S. Federal withholding
            tax, as applicable, in all cases such forms and other documents
            being properly completed and duly executed by such Non-U.S.
            Debenture Holder claiming complete exemption from U.S. Federal
            withholding tax on payments of interest (or of original issue
            discount) for U.S. Federal income tax purposes by the Company under
            the Debentures. Each Buyer, each Warrant holder and each holder of
            common stock that is organized under the laws of a jurisdiction
            other than the United States, any State thereof or the District of
            Columbia (each a "Non-U.S. Equity Holder") also shall deliver to the
            Company, to the extent legally able to do so, with respect to
            payments of dividends for U.S. Federal income tax purposes by the
            Company, if applicable, two copies of either (A) U.S. Internal
            Revenue Service Form W-8BEN (claiming a reduction of U.S. Federal
            withholding tax under an applicable income tax treaty, if any), or
            any successor form, (B) U.S. Internal Revenue Service Form W-8ECI
            (claiming complete exemption from U.S. Federal withholding tax
            because the income is effectively connected with a U.S. trade or
            business), or any successor form, or (C) other applicable form,
            certificate or document prescribed by the U.S. Internal Revenue
            Service certifying as to such Non-U.S. Equity Holder's entitlement
            to an

                                       18
<PAGE>

            exemption from, or a reduction of, U.S. Federal withholding tax on
            payments of dividends for U.S. Federal income tax purposes by the
            Company, as applicable, in all cases such forms and other documents
            being properly completed and duly executed by such Non-U.S. Equity
            Holder. In addition, each Buyer, each Debenture holder, each Warrant
            holder, and each holder of Common Stock that is not otherwise exempt
            from "back-up withholding" shall deliver to the Company two properly
            completed and duly executed copies of either (A) U.S. Internal
            Revenue Service Form W-8BEN, or any successor form, (B) U.S.
            Internal Revenue Service Form W-8ECI, or any successor form, (C)
            U.S. Internal Revenue Service Form W-9, or any successor form, or
            (D) other applicable form, certificate or document prescribed by the
            U.S. Internal Revenue Service, as applicable, in each case
            indicating that such Buyer, Debenture holder, Warrant holder, or
            holder of Common Stock is not subject to "back-up withholding" for
            U.S. Federal income tax purposes. The forms and other documents
            required to be delivered pursuant to this Section 4(m)(ii) shall be
            delivered (A) on or prior to the Closing Date and (B) from time to
            time thereafter if within ten (10) Business Days after receipt of a
            written request therefor by the Company. In addition, each Buyer,
            each Debenture holder, each Warrant holder and each holder of Common
            Stock shall promptly notify the Company at any time it determines
            that it is no longer in a position to provide any previously
            delivered (or requested) form, document or certificate to the
            Company, including as a result in whole or in part from a Change in
            Law; provided, however, that the failure to provide such notice
            shall not affect any Buyer's or Debenture holder's right to any
            additional amounts hereunder.

                        (iii) Notwithstanding anything to the contrary in
            Section 4(m)(ii) above, the Company shall not be required to pay any
            additional amount to any Buyer or any Debenture holder pursuant to
            the preceding paragraph to the extent the Tax in respect of which
            such additional amount would otherwise be payable would not have
            been imposed but for the failure of such Buyer or Debenture holder
            to comply with its obligations under such paragraph; provided,
            however, that the failure to provide the applicable form, document
            or certificate pursuant to the preceding paragraph as provided in
            the notice required by the preceding paragraph resulting in whole or
            in part from a Change in Law shall not affect such Buyer's or
            Debenture holder's right to any additional amounts hereunder.

            n. Violations of Law. The business of the Company and its
Subsidiaries shall not be conducted in violation of any law, ordinance or
regulation of any governmental entity, except where such violations would not
result, either individually or in the aggregate, in a Material Adverse Effect.

            o. Corporate Existence. So long as a Buyer beneficially owns any
Securities, the Company shall maintain its corporate existence and shall not
sell all or substantially all of the Company's assets, except in the event of a
merger or consolidation or sale of all or substantially all of the Company's
assets, where the surviving or successor entity in such transaction (i) assumes
the Company's obligations hereunder and under the Transaction Documents and (ii)
such surviving or successor entity or its parent into whose stock the Debentures
and Warrants will be convertible or exercisable is a publicly traded corporation
whose common stock is listed for trading on or quoted on AMEX, NYSE or NASDAQ.

                                       19
<PAGE>

            p. Short Positions. Each Buyer agrees that on any Business Day prior
to the time such Buyer no longer holds any Debentures, such Buyer shall not
maintain a Net Short Position. For purposes hereof, "Net Short Position" shall
mean that the aggregate number of shares of Common Stock held in a short
position by such Buyer exceeds the sum of (1) the number of Conversion Shares,
Warrant Shares and Interest Shares then issuable (without regard to any
limitations on conversions or exercise) to such Buyer, (2) the number of
conversion shares, warrant shares and interest shares then issuable (without
regard to any limitations on conversions or exercise) to such Buyer in
connection with the securities issued to such Buyer pursuant to the Securities
Purchase Agreement, dated as of March 12, 2003, between the Company and such
Buyer (the "March Securities"), (3) the number of warrant shares then issuable
(without regard to any limitations on exercise) to such Buyer pursuant to that
certain Warrant To Purchase Common Stock issued by the Company to such Buyer on
June 25, 2003 (the "June Securities"), and (4) the number of conversion shares,
warrant shares and interest shares then issuable (without regard to any
limitations on conversions or exercise) to such Buyer in connection with the
securities issued to such Buyer pursuant to the Securities Purchase Agreement,
dated as of July 10, 2003, between the Company and such Buyer (the "July
Securities").

            q. Letter of Credit. Pursuant to this subsection, the Company shall
cause to be issued and delivered to Portside Growth & Opportunity Fund, as
collateral agent for the Buyers (in such capacity, together with any successor
in such capacity, the "Agent"), four (4) irrevocable standby letters of credit
in the stated amount of $250,000 each ($1,000,000 in the aggregate),
substantially in the form of Exhibit D hereto and otherwise reasonably
satisfactory to the Buyers (together with any letter of credit issued in
exchange therefor or in replacement thereof, each a "Letter of Credit"), naming
the Agent as beneficiary and issued by a bank with a Minimum Rating and
otherwise acceptable to the Agent in its reasonable discretion; provided,
however, that prior identical letters of credit (as amended) in the stated
amount of $1,000,000 in the aggregate issued to the Agent may be used instead
subject to such further amendments as the Agent may reasonably require. As used
herein, "Minimum Rating" shall mean one of the two highest long-term debt
ratings, without regard to qualification by symbols, such as "+" and "-", or by
numerical notations, such as "1", "2" and "3" (or if no long-term debt rating is
available, one of the two highest long-term deposit ratings) obtainable from
either Standard & Poor's Ratings Services ("S&P") or Moody's Investors Service,
Inc. ("Moody's") (or if at any time neither S&P nor Moody's shall issue such
ratings, then from another nationally recognized rating service). The Buyers
agree to pay at the Closing for all reasonable and customary fees in connection
with the Letter of Credit provided, that such fees do not exceed $20,000. Each
Letter of Credit shall be delivered within seven (7) days following the Closing.
The Company shall have the right, at any time and from time to time, to cause to
be issued and delivered to the Agent a replacement for any Letter of Credit
previously issued and delivered, provided, that such replacement is
substantially in the form of the Letter of Credit being exchanged or replaced
therefor and is otherwise acceptable to the Agent in its sole discretion. Upon
delivery of a replacement Letter of Credit, the Agent shall immediately deliver
the original Letter of Credit being exchanged therefor. The Letters of Credit
shall not be drawn upon by the Buyers unless the obligations of the Company
pursuant to the Transaction Documents are not otherwise satisfied pursuant to
the terms of the Transaction Documents.

                                       20
<PAGE>

            r. Cash Collateral Account. Simultaneously with the Closing
hereunder, the Company shall establish with a bank acceptable to the Agent (the
"Cash Collateral Bank") a deposit account (together with all monies on deposit
in such deposit account and all certificates and instruments, if any,
representing or evidencing such deposit account, the "Cash Collateral Account"),
and shall cause the Cash Collateral Bank to enter into an Account Control
Agreement with the Agent, substantially in the form of Exhibit E (as amended
from time to time, the "Account Control Agreement"); provided, however, that
prior account control agreements (as amended) entered into by the Company for
the benefit of the Agent may be used instead subject to such further amendments
as the Agent may reasonably require. The Cash Collateral Account shall at all
times be under the dominion and control of the Agent. The Company shall deliver
to the Agent (for the benefit of the Buyers) any opinion that the Agent may
reasonably request in connection with the Account Control Agreement.

            s. Perfected First Security Interest- Personal Property. The Company
shall execute and deliver to the Agent the Security Agreement at Closing,
substantially in the form of Exhibit F hereto (as amended and/or restated from
time to time, the "Security Agreement"), pursuant to which the Company shall
grant to the Agent, for the benefit of the Buyers, a perfected, first priority
security interest in all of its now owned and hereafter acquired personal
property other than intellectual property (the "Personal Property Collateral");
provided, however, that a prior security agreement (as amended) entered into by
the Company for the benefit of the Agent may be used instead subject to such
further amendments as the Agent may reasonably require. The Company shall also
shall take such other action and execute, acknowledge and deliver such other
agreements, instruments or other documents as the Agent may require from time to
time in order (i) to carry out more effectively the purposes of the Security
Agreement, (ii) to subject to valid and perfected first priority liens any of
the Personal Property Collateral, (iii) to establish and maintain the validity
and effectiveness of the Security Agreement or such other agreements,
instruments or other documents and the validity, perfection and priority of the
liens intended to be created thereby, and (iv) to better assure, convey, grant,
assign, transfer and confirm unto each of the Agent and the Buyers the rights
now or hereafter intended to be granted to it under the Security Agreement
(including, without limitation, by (w) executing any amendment to the Security
Agreement as may be reasonably requested by the Buyers, (x) by causing insurance
certificates satisfactory to the Buyers naming the Buyers as "loss payee" or
"additional insured" on all of the Company's property and liability insurance to
be issued, (y) by using its reasonable commercial efforts to obtain landlord
waivers reasonably satisfactory to the Buyers in connection with the Company's
leasehold premises where Personal Property Collateral is located and (z) by
cooperating with the Buyers to finalize and execute a perfection certificate to
include, among other things, information relating to the acquisition of certain
Interferon assets.). In furtherance of the foregoing, to the maximum extent
permitted by applicable law, the Company (i) authorizes the Agent to execute any
such agreements, instruments or other documents in the Company's name and to
file such agreements, instruments or other documents in any appropriate filing
office, (ii) authorizes the Agent to file any financing statement required
hereunder or under the Security Agreement, and any continuation statement or
amendment with respect thereto, in any appropriate filing office without the
signature of the Company, and (iii) ratifies the filing of any financing
statement, and any continuation statement or amendment with respect thereto,
filed without the signature of the Company prior to the date hereof.

                                       21
<PAGE>

            t. Perfected First Security Interest - Real Property. Within 90 days
of the Closing Date, the Company shall:

                        (i) execute and deliver to the Agent a mortgage, deed of
            trust or deed to secure debt for each real property location (the
            "Properties") acquired by the Company from the Interferon Sciences,
            Inc. (the "Seller"), each in recordable form and containing such
            terms, covenants and provisions and in all other respects reasonably
            acceptable to the Agent in its sole discretion (as amended from time
            to time, each a "Mortgage" and collectively, the "Mortgages"),
            pursuant to which the Company shall grant to the Agent, for the
            benefit of the Buyers, a perfected first priority security interest
            and mortgage lien in the Properties and all improvements located
            thereon (the "Real Property Collateral"; together with the Personal
            Property Collateral, collectively, the "Collateral");

                        (ii) furnish to the Agent the following, each in form
            and substance reasonably satisfactory to the Agent:

                                    (A) evidence of the recording of each
                        Mortgage referred to in clause (i) above in such office
                        or offices as may be necessary or, in the reasonable
                        opinion of the Agent, desirable to create and perfect a
                        valid and enforceable first priority lien on the
                        property purported to be covered thereby or to otherwise
                        protect the rights of the Agent and the Buyers
                        thereunder;

                                    (B) an ALTA form of mortgage loan title
                        insurance policy, in form and substance reasonably
                        satisfactory to the Agent, issued by or on behalf of a
                        title insurance company reasonably satisfactory to the
                        Agent, insuring the mortgage lien created by each
                        Mortgage for an amount not less than $1,500,000, subject
                        only to such exceptions to title as the Agent may
                        reasonably accept and approve and with such endorsements
                        and affirmative insurance as the Agent may reasonably
                        require, and otherwise on terms satisfactory to the
                        Agent (a "Title Insurance Policy");

                                    (C) an ALTA survey of each Property,
                        certified to the Agent and to the issuer of the
                        applicable Title Insurance Policy by a licensed land
                        surveyor reasonably satisfactory to the Agent (a
                        "Survey");

                                    (D) a satisfactory ASTM 1527-00 Phase I
                        Environmental Site Assessment ("Phase I ESA") for each
                        Property (and, if reasonably requested by the Agent
                        based upon the results of such Phase I ESA, an ASTM
                        1527-00 Phase II Environmental Site Assessment ("Phase
                        II ESA") for such Property), each in form and substance
                        and by an independent firm satisfactory to the Agent;

                                    (E) an opinion of counsel for the Company as
                        to such matters regarding each Mortgage (including the
                        due authorization, execution and delivery of the
                        Mortgage, the validity and enforceability of the
                        Mortgage and its

                                       22
<PAGE>

                        compliance with the law of the jurisdiction in which the
                        relevant Property is located) as the Agent may
                        reasonably require; and

                                    (F) such other instruments and documents,
                        including estoppel certificates, permits, licenses,
                        approvals, violation reports, plans and engineering
                        studies, regarding each such Property as the Agent may
                        require; and

                        (iii) take such other action and execute, acknowledge
            and deliver such other agreements, instruments or other documents as
            the Agent may reasonably require from time to time in order to (A)
            carry out more effectively the purposes of each Mortgage, (B)
            subject to valid and perfected first priority liens any of the Real
            Property Collateral, (C) establish and maintain the validity and
            effectiveness of each Mortgage or such other agreements, instruments
            or other documents and the validity, perfection and priority of the
            liens intended to be created thereby, and (D) better assure, convey,
            grant, assign, transfer and confirm unto each of the Agent and the
            Buyers the rights intended to be granted to it under each Mortgage.
            In furtherance of the foregoing, to the maximum extent permitted by
            applicable law, the Company (x) authorizes the Agent to execute any
            such agreements, instruments or other documents in the Company's
            name and to file or record such agreements, instruments or other
            documents in any appropriate filing or recording office, (y)
            authorizes the Agent to file any financing statement required
            hereunder or under any Mortgage, and any continuation statement or
            amendment with respect thereto, in any appropriate filing office
            without the signature of the Company, and (z) ratifies the filing of
            any financing statement, and any continuation statement or amendment
            with respect thereto, filed without the signature of the Company
            prior to the date hereof.

            u. Acquisition of Interferon Sciences, Inc. The Company shall
acquire certain assets of the Seller pursuant to certain valid and binding
purchase and sale agreements, executed copies (together with all exhibits and
schedules thereto) of which are attached hereto as Exhibit G-1 (the "Interferon
Inventory and License Agreement") and Exhibit G-2 (the "Interferon Asset
Agreement" and together with the Interferon Inventory and License Agreement, the
"Interferon Agreements"), within ninety (90) days of the Closing. The Company
shall not make or permit to be made any amendment or modification to either
Interferon Agreement or the transactions contemplated thereby without Buyers'
prior written consent. All of the consideration (including, without limitation,
all shares of Common Stock (whether issued or issuable to Seller or otherwise as
set forth in the Interferon Agreements), the satisfaction of certain
obligations, royalties, fees for employees and for services, the assumption of
payables) to be paid by the Company in connection with the Interferon Agreements
is as set forth on Schedule 4(u) hereof.

            v. Certain Accounts. The Company represents and warrants to each
Buyer that Schedule 4(v) hereto sets forth a full and complete list of every
bank and other financial institution at which the Company presently has an
account (each, an "Existing Account"). The Company represents and warrants to
each Buyer that (1) the Company has deposited or otherwise transferred any and
all funds, including (without any limitation) those funds released from any
Existing Account that does not become a Permitted Account (as defined) pursuant
hereto, to the First Union National Bank Account Nos. 20000009652305,

                                       23
<PAGE>

2100043128724 and/or 4166-9926 (the "First Union Accounts"), and (2) the Company
has caused each Existing Account denoted with an asterisk on Schedule 4(v) to be
a Permitted Account, and the Company shall use its best commercial efforts to
obtain the signature of each depository institution reasonably requested by any
Buyer to sign a Bank Agreement in connection with such Existing Account becoming
a Permitted Account and shall deliver to the Agent (for the benefit of the
Buyers) any opinion that the Agent may reasonably request in connection with the
applicable Bank Agreement. In addition, the Company shall take the following
actions with respect to the Existing Accounts:

                        (i) The Company shall immediately deposit any funds
            released from time to time from the First Union/Wachovia Investments
            Account No. 4167-7452 into an account for which the Agent has
            executed a Bank Agreement reasonably satisfactory to the Buyers (any
            such account being a "Permitted Account");

                        (ii) The Company shall not deposit or otherwise transfer
            any funds into any foreign account without the prior written consent
            of the Buyers; provided, however, that the Company may make such
            deposits or transfers to such foreign accounts in connection with
            ordinary course business expenses to the extent that the aggregate
            balance in all such foreign accounts does not exceed $25,000; and

                        (iii) The Company shall not deposit or otherwise
            transfer any funds to any account that is not a Permitted Account;
            provided, however, that the Company may make such deposits or
            transfers to an Existing Account that is not a Permitted Account to
            the extent that the balance in any such Existing Account does not
            exceed $5,000.

      Immediately upon the occurrence of a default or Event of Default or event
that with notice or lapse of time would constitute a Default or Event of
default, the company agrees that the Agent under the Account Control Agreement
or any Bank Agreement shall be authorized to send one or more "notices of
exclusive control" (as defined in the Account Control Agreement or relevant Bank
Agreement) (or an analogous notice described in the Account Control Agreement or
relevant Bank Agreement) to the depositary bank(s) party thereto prohibiting
such bank(s) from accepting any further instructions from the Company in
connection with any property held in any account therein.

            w. Certain Amendments. (i) The Company and each Buyer hereby agree
that the Company's $5,426,000 principal amount of its 6% Senior Secured
Convertible Debentures due July 31, 2005 (the "July Debentures") are hereby
amended such that the "Conversion Price" shall mean as of any Conversion Date
(as defined in the July Debentures) or other date of determination $1.89,
subject to adjustment as provided in Section 6 of the July Debentures. Each
Buyer waives any rights it may have under antidilution provisions in any of the
March Securities, June Securities, July Securities, the Debentures or the
Warrants solely with respect to the amendment of such Conversion Price. On the
Business Day following the Closing Date, the Company shall prepare and file with
the SEC such amendments or supplements to the Company's Registration Statement
on Form S-1 (File No. 333-108645), which prospectus is to be filed pursuant to
Rule 424 promulgated under the 1933 Act, relating to the amendment of the
Conversion Price described herein.

                                       24
<PAGE>

            (ii) Notwithstanding anything to the contrary in the March
Debentures, the July Debentures or the Debentures, the Company shall not be
obligated to make any collateral payments pursuant to Section 25(g) of the March
Debentures, the July Debentures or the Debentures (whether in cash or in shares
of Common Stock) on any Biweekly Revenue Cash Collateral Date, Monthly Revenue
Cash Collateral Date, the First Revenue Milestone Cash Collateral Date, the
Second Revenue Milestone Cash Collateral Date, or the Third Revenue Milestone
Cash Collateral Date (each, as defined in the March Debentures, the July
Debentures and the Debentures, respectively) to the extent that the balance in
the Cash Collateral Account (as defined in the Securities Purchase Agreements
relating to the March Debentures and the July Debentures and as defined herein,
respectively) is not less than $1,300,000 in the aggregate.

            5. TRANSFER AGENT INSTRUCTIONS.

      The Company shall issue irrevocable instructions to its transfer agents,
and any subsequent transfer agent, to issue certificates or credit shares to the
applicable balance accounts at DTC, registered in the name of each Buyer or its
respective nominee(s), for the Conversion Shares and Warrant Shares in such
amounts as specified from time to time by each Buyer to the Company upon
conversion of the Debentures or exercise of the Warrants, as applicable and in
accordance with their respective terms (the "Irrevocable Transfer Agent
Instructions"), a form of which is attached as Exhibit H hereto. Prior to
transfer or sale pursuant to a registration statement or Rule 144 under the 1933
Act of the Conversion Shares and the Warrant Shares, all such certificates shall
bear the restrictive legend specified in Section 2(g) of this Agreement. The
Company warrants that no instruction inconsistent with the Irrevocable Transfer
Agent Instructions referred to in this Section 5 and stop transfer instructions
to give effect to Section 2(f) hereof (in the case of the Conversion Shares, the
Warrant Shares the Interest Shares and the Repayment Shares, prior to
registration of the Conversion Shares and the Warrant Shares under the 1933 Act)
will be given by the Company to its transfer agent and that the Securities shall
otherwise be freely transferable on the books and records of the Company as and
to the extent provided in this Agreement, the Debentures, the Warrants and the
Registration Rights Agreement. If a Buyer provides the Company with an opinion
of counsel, in generally acceptable form, to the effect that a public sale,
assignment or transfer of Securities may be made without registration under the
1933 Act or that the Securities can be sold pursuant to Rule 144 without any
restriction as to the number of securities acquired as of a particular date that
can then be immediately sold, the Company shall permit the transfer, and, in the
case of the Conversion Shares, the Warrant Shares, the Interest Shares and the
Repayment Shares, promptly instruct its transfer agent to issue one or more
certificates, or credit shares to one or more balance accounts at DTC, in such
name and in such denominations as specified by such Buyer and without any
restrictive legend. The Company acknowledges that a breach by it of its
obligations hereunder will cause irreparable harm to the Buyers by vitiating the
intent and purpose of the transaction contemplated hereby. Accordingly, the
Company acknowledges that the remedy at law for a breach of its obligations
under this Section 5 will be inadequate and agrees, in the event of a breach or
threatened breach by the Company of the provisions of this Section 5, that the
Buyers shall be entitled, in addition to all other available remedies, to an
order and/or injunction restraining any breach and requiring immediate issuance
and transfer, without the necessity of showing economic loss and without any
bond or other security being required.

                                       25
<PAGE>

      6. CONDITIONS TO THE COMPANY'S OBLIGATION TO SELL.

            a. The obligation of the Company to issue and sell the Debentures
and the Warrants to each Buyer at the Closing is subject to the satisfaction, at
or before the Closing Date, of each of the following conditions, provided that
these conditions are for the Company's sole benefit and may be waived by the
Company at any time in its sole discretion by providing each Buyer with prior
written notice thereof:

                        (i) Such Buyer shall have executed each of the
            Transaction Documents to which it is a party and delivered the same
            to the Company.

                        (ii) Such Buyer shall have delivered to the Company the
            purchase price (less any amounts withheld pursuant to Section 4(k))
            for the Debentures and the Warrants being purchased by such Buyer at
            the Closing, by wire transfer of immediately available funds
            pursuant to the wire instructions provided by the Company.

                        (iii) The representations and warranties of such Buyer
            shall be true and correct in all material respects (except to the
            extent that any of such representations and warranties is already
            qualified as to materiality in Section 2 above, in which case such
            representations and warranties shall be true and correct without
            further qualification) as of the date when made and as of the
            Closing Date as though made at that time (except for representations
            and warranties that speak as of a specific date (which shall be true
            and correct as of such date)), and such Buyer shall have performed,
            satisfied and complied with in all material respects the covenants,
            agreements and conditions required by the Transaction Documents to
            be performed, satisfied or complied with by such Buyer at or prior
            to the Closing Date.

                        (iv) Such Buyer shall have delivered to the Company the
            amount set forth under the heading "Second Payment Amount" opposite
            such Buyer's name on the Schedule of Buyers in the Securities
            Purchase Agreement relating to the purchase of the July Securities
            (less any amounts withheld pursuant to Section 4(k) of such
            Securities Purchase Agreement), by wire transfer of immediately
            available funds pursuant to the wire instructions provided by the
            Company.

      7. CONDITIONS TO EACH BUYER'S OBLIGATION TO PURCHASE.

            a. The obligation of each Buyer hereunder to purchase the Debentures
and the Warrants from the Company at the Closing is subject to the satisfaction,
at or before the Closing Date, of each of the following conditions, provided
that these conditions are for each Buyer's sole benefit and may be waived by
such Buyer at any time in its sole discretion by providing the Company with
prior written notice thereof:

                        (i) The Company shall have executed each of the
            Transaction Documents and delivered the same to such Buyer.

                        (ii) (1) The Common Stock (x) shall be designated for
            quotation or listed on the Principal Market and (y) shall not have
            been suspended by the SEC or the Principal Market from trading on
            the Principal Market nor shall suspension by

                                       26
<PAGE>

            the SEC or the Principal Market have been threatened either (A) in
            writing by the SEC or the Principal Market or (B) by falling below
            the minimum listing maintenance requirements of the Principal
            Market; and (2) the Company shall promptly file a new listing
            application and use its best efforts to cause the Conversion Shares
            issuable upon conversion of the Debentures (without regard to any
            limitations on conversions), the Warrant Shares issuable upon
            exercise of the Warrants (without regard to any limitations on
            exercises) to be listed (subject to official notice of issuance) on
            the Principal Market and the maximum number of Interest Shares and
            Repayment Shares issuable over the full term of the Debentures
            (assuming the Company paid the maximum amount of interest permitted
            to be paid in Interest Shares over the full term of the Debentures)
            to be approved for listing on the Principal Market not later than 10
            days following the Closing Date.

                        (iii) The representations and warranties of the Company
            shall be true and correct in all material respects (except to the
            extent that any of such representations and warranties is already
            qualified as to materiality in Section 3 above, in which case such
            representations and warranties shall be true and correct without
            further qualification) as of the date when made and as of the
            Closing Date as though made at that time (except for representations
            and warranties that speak as of a specific date (which shall be true
            and correct as of such date)) and the Company shall have performed,
            satisfied and complied with in all material respects the covenants,
            agreements and conditions required by the Transaction Documents to
            be performed, satisfied or complied with by the Company at or prior
            to the Closing Date.

                        (iv) The Company shall have delivered to such Buyer the
            opinion of Ransom W. Etheridge, Esq. counsel to the Company, dated
            as of the Closing Date, in the form of Exhibit I attached hereto.

                        (v) The Company shall have executed and delivered to
            such Buyer the Debentures and the Warrants (in such denominations as
            such Buyer shall reasonably request) being purchased by such Buyer
            at the Closing.

                        (vi) As of the Closing Date, the Company shall have
            reserved out of its authorized and unissued Common Stock, solely for
            the purpose of effecting the conversion of the Debentures, the
            exercise of the Warrants, and the payment of interest in the form of
            Interest Shares (assuming the Company paid the maximum amount of
            interest permitted to be paid in Interest Shares over the full term
            of the Debentures) 3,654,297 shares of its Common Stock.

                        (vii) The Company shall have delivered the Irrevocable
            Transfer Agent Instructions, in the form of Exhibit H attached
            hereto, to the Company's transfer agent.

                        (viii) The Company shall have delivered to such Buyer a
            secretary's certificate, dated as of the Closing Date, certifying as
            to (A) adoption of the form of resolutions of the Board of Directors
            of the Company consistent with Section

                                       27
<PAGE>

            3(b) above (the "Resolutions"), (B) the Certificate of Incorporation
            and (C) the By-laws, each as in effect at the Closing.

                        (ix) The Company shall have made all filings under all
            applicable federal and state securities laws necessary to consummate
            the issuance of the Securities pursuant to this Agreement in
            compliance with such laws.

                        (x) The Bank Agreement(s) relating to the First Union
            Accounts (the "First Union Bank Agreements") shall have been
            executed and delivered to the Agent (for the benefit of the Buyers);
            provided, however, that a prior bank agreement entered into by First
            Union and the Company for the benefit of the Agent may be used
            instead subject to such amendments as the Agent may reasonably
            require.

                        (xi) The Company shall have deposited in the Cash
            Collateral Account not less than $1,300,000 in the aggregate
            (inclusive of funds already on deposit in such account).

      8. INDEMNIFICATION. In consideration of each Buyer's execution and
delivery of the Transaction Documents and acquiring the Securities thereunder
and in addition to all of the Company's other obligations under the Transaction
Documents, the Company shall defend, protect, indemnify and hold harmless each
Buyer, each holder of Debentures and Warrants and each affiliate of any Buyer
holding Securities and all of their stockholders, partners, members, officers,
directors, employees and direct or indirect investors and any of the foregoing
persons' agents or other representatives (including, without limitation, those
retained in connection with the transactions contemplated by this Agreement)
(collectively, the "Indemnitees") from and against any and all actions, causes
of action, suits, claims, losses, costs, penalties, fees, liabilities and
damages, and expenses in connection therewith (irrespective of whether any such
Indemnitee is a party to the action for which indemnification hereunder is
sought), and including reasonable attorneys' fees and disbursements, but
excluding amounts covered by Section 4(m)(ii) hereof (the "Indemnified
Liabilities"), incurred by any Indemnitee as a result of or arising out of, or
relating to (a) any misrepresentation or breach of any representation or
warranty made by the Company in the Transaction Documents or (b) any breach of
any covenant, agreement or obligation of the Company contained in the
Transaction Documents, (c) the exercise or enforcement of any of the rights of
the Buyers under the Pledge and Security Agreement or the foreclosure, sale,
liquidation or other disposition of, or realization upon, the Collateral
including, without limitation, the transfer of the Collateral to the Buyers, or
(d) any cause of action, suit or claim brought or made against such Indemnitee
(other than a cause of action, suit or claim which is (x) brought or made by the
Company and (y) is not a shareholder derivative suit) and arising out of or
resulting from (i) the execution, delivery, performance or enforcement of the
Transaction Documents or any other certificate, instrument or document
contemplated hereby or thereby, (ii) any transaction financed or to be financed
in whole or in part, directly or indirectly, with the proceeds of the issuance
of the Securities or (iii) the status of such Buyer, such holder of Debentures
and Warrants and any such affiliate of any Buyer holding Securities as an
investor in the Company. To the extent that the foregoing undertaking by the
Company may be unenforceable for any reason, the Company shall make the maximum
contribution to the payment and satisfaction of each of the Indemnified
Liabilities which is permissible under applicable law. Except as otherwise set
forth herein, the mechanics

                                       28
<PAGE>

and procedures with respect to the rights and obligations under this Section 8
shall be the same as those set forth in Sections 6(a) and (d) of the
Registration Rights Agreement, including, without limitation, those procedures
with respect to the settlement of claims and the Company's rights to assume the
defense of claims.

      9. MISCELLANEOUS.

            a. Governing Law; Jurisdiction; Jury Trial. All questions concerning
the construction, validity, enforcement and interpretation of this Agreement
shall be governed by the internal laws of the State of New York, without giving
effect to any choice of law or conflict of law provision or rule (whether of the
State of New York or any other jurisdiction) that would cause the application of
the laws of any jurisdiction other than the State of New York. Each party hereby
irrevocably submits to the non-exclusive jurisdiction of the state and federal
courts sitting in The City of New York, Borough of Manhattan, for the
adjudication of any dispute hereunder or in connection herewith or with any
transaction contemplated hereby or discussed herein, and hereby irrevocably
waives, and agrees not to assert in any suit, action or proceeding, any claim
that it is not personally subject to the jurisdiction of any such court, that
such suit, action or proceeding is brought in an inconvenient forum or that the
venue of such suit, action or proceeding is improper. Each party hereby
irrevocably waives personal service of process and consents to process being
served in any such suit, action or proceeding by mailing a copy thereof to such
party at the address for such notices to it under this Agreement and agrees that
such service shall constitute good and sufficient service of process and notice
thereof. Nothing contained herein shall be deemed to limit in any way any right
to serve process in any manner permitted by law. EACH PARTY HEREBY IRREVOCABLY
WAIVES ANY RIGHT IT MAY HAVE, AND AGREES NOT TO REQUEST, A JURY TRIAL FOR THE
ADJUDICATION OF ANY DISPUTE HEREUNDER OR IN CONNECTION HEREWITH OR ARISING OUT
OF THIS AGREEMENT OR ANY TRANSACTION CONTEMPLATED HEREBY.

            b. Counterparts. This Agreement may be executed in two or more
identical counterparts, all of which shall be considered one and the same
agreement and shall become effective when counterparts have been signed by each
party and delivered to the other party; provided that a facsimile signature
shall be considered due execution and shall be binding upon the signatory
thereto with the same force and effect as if the signature were an original, not
a facsimile signature.

            c. Headings. The headings of this Agreement are for convenience of
reference and shall not form part of, or affect the interpretation of, this
Agreement.

            d. Severability. If any provision of this Agreement shall be invalid
or unenforceable in any jurisdiction, such invalidity or unenforceability shall
not affect the validity or enforceability of the remainder of this Agreement in
that jurisdiction or the validity or enforceability of any provision of this
Agreement in any other jurisdiction.

            e. Entire Agreement; Amendments. This Agreement supersedes all other
prior oral or written agreements between each Buyer, the Company, their
affiliates and persons acting on their behalf with respect to the matters
discussed herein, and this Agreement and the

                                       29
<PAGE>

instruments referenced herein contain the entire understanding of the parties
with respect to the matters covered herein and therein and, except as
specifically set forth herein or therein, neither the Company nor any Buyer
makes any representation, warranty, covenant or undertaking with respect to such
matters. No provision of this Agreement may be amended or waived other than by
an instrument in writing signed by the Company and the holders of at least 60%
of the outstanding principal amount of the Debentures or Conversion Shares, as
applicable. No such amendment shall be effective to the extent that it applies
to less than all of the holders of the Debentures then outstanding. No
consideration shall be offered or paid to any person to amend or consent to a
waiver or modification of any provision of any of the Transaction Documents
unless the same consideration also is offered to all of the parties to the
Transaction Documents or holders of the Conversion Shares, as the case may be.

            f. Notices. Any notices, consents, waivers or other communications
required or permitted to be given under the terms of this Agreement must be in
writing and will be deemed to have been delivered: (i) upon receipt, when
delivered personally; (ii) upon receipt, when sent by facsimile (provided
confirmation of transmission is mechanically or electronically generated and
kept on file by the sending party); or (iii) one (1) Business Day after deposit
with a nationally recognized overnight delivery service, in each case properly
addressed to the party to receive the same. The addresses and facsimile numbers
for such communications shall be:

            If to the Company:

                     Hemispherx Biopharma, Inc.
                     One Penn Center
                     1617 JFK Boulevard, Suite 660
                     Philadelphia, Pennsylvania 19103
                     Telephone:       (215) 988-0080
                     Facsimile:       (215) 988-1739
                     Attention:       Chief Executive Officer

            With copies to:

                     Ransom W. Etheridge, Esq.
                     2610 Potters Road
                     Suite 200
                     Virginia Beach, VA  23452
                     Telephone:       (757) 486-0599
                     Facsimile:       (757) 486-0792

                                       30
<PAGE>

            If to the Transfer Agent:

            Continental Stock Transfer & Trust Company
                             2 Broadway
                             New York, NY 10004
                             Telephone:       (212) 509-4000
                             Facsimile:       (212) 509-5150

      If to a Buyer, to it at the address and facsimile number set forth on the
Schedule of Buyers, with copies to such Buyer's representatives as set forth on
the Schedule of Buyers, or at such other address and/or facsimile number and/or
to the attention of such other person as the recipient party has specified by
written notice given to each other party five (5) days prior to the
effectiveness of such change. Written confirmation of receipt (A) given by the
recipient of such notice, consent, waiver or other communication, (B)
mechanically or electronically generated by the sender's facsimile machine
containing the time, date, recipient facsimile number and an image of the first
page of such transmission or (C) provided by a nationally recognized overnight
delivery service shall be rebuttal evidence of personal service, receipt by
facsimile or receipt from a nationally recognized overnight delivery service in
accordance with clause (i), (ii) or (iii) above, respectively.

            g. Successors and Assigns. This Agreement shall be binding upon and
inure to the benefit of the parties and their respective successors and assigns,
including any purchasers of the Securities; provided, however, that such
successor or assignee shall deliver the forms specified in Section 4(m)(ii) as
if it were a "Buyer." The Company shall not assign this Agreement or any rights
or obligations hereunder without the prior written consent of the holders of at
least 60% of the outstanding principal amount of the Debentures, including by
merger or consolidation. A Buyer may assign some or all of its rights and
obligations hereunder without the consent of the Company; provided, however,
that the transferee has agreed in writing to be bound by the applicable
provisions of this Agreement and provided, further, that such assignment shall
be in connection with a transfer of all or a portion of the Debentures and
Warrants held by such Buyer and subject to the terms and conditions of the
Warrants and Debentures, as applicable. Any such assignment shall only be
effective upon the Company's receipt of written notice thereof. Any Buyer shall
be entitled to pledge the Securities in connection with a bona fide margin
account or other loan secured by the Securities and the pledge of Securities
shall not be deemed to be a transfer, sale or assignment of the Securities
hereunder, and no Investor effecting a pledge of Securities shall be required to
provide the Company with any notice thereof or otherwise make any delivery to
the Company pursuant to this Agreement or any other Transaction Document,
including, without limitation, Section 2(f) of this Agreement; provided that in
order to make any sale, transfer or assignment of Securities, such Investor and
its pledgee makes such disposition in accordance with or pursuant to a
registration statement or an exemption under the 1933 Act.

            h. No Third Party Beneficiaries. This Agreement is intended for the
benefit of the parties hereto and their respective permitted successors and
assigns, and is not for the benefit of, nor may any provision hereof be enforced
by, any other person.

                                       31
<PAGE>

            i. Survival. Unless this Agreement is terminated under Section 9(l),
the representations and warranties of the Company and the Buyers contained in
Sections 2 and 3, the agreements and covenants set forth in Sections 4, 5 and 9,
and the indemnification provisions set forth in Section 8, shall survive until
such time as no Debentures remain outstanding. Each Buyer shall be responsible
only for its own representations, warranties, agreements and covenants
hereunder.

            j. Publicity. The Company and each Buyer shall have the right to
approve before issuance any press releases or any other public statements with
respect to the transactions contemplated hereby; provided, however, that the
Company shall be entitled, without the prior approval of any Buyer, to (i) file
a Form 8-K, substantially in the form attached hereto as Exhibit J, after the
Closing, (ii) make any press release or other public disclosure of information
that previously has been publicly disclosed (other than pursuant to a breach of
this paragraph), and (iii) make any press release or other public disclosure
with respect to such transactions in the form as is required by applicable law
and regulations.

            k. Further Assurances. Each party shall do and perform, or cause to
be done and performed, all such further acts and things, and shall execute and
deliver all such other agreements, certificates, instruments and documents, as
the other party may reasonably request in order to carry out the intent and
accomplish the purposes of this Agreement and the consummation of the
transactions contemplated hereby.

            l. Termination. In the event that the Closing shall not have
occurred with respect to a Buyer on or before five (5) Business Days from the
date hereof due to the Company's or such Buyer's failure to satisfy the
conditions set forth in Sections 6 and 7 above (and the nonbreaching party's
failure to waive such unsatisfied condition(s)), the nonbreaching party shall
have the option to terminate this Agreement with respect to such breaching party
at the close of business on such date without liability of any party to any
other party; provided, however, that if this Agreement is terminated pursuant to
this Section 9(l), the Company shall remain obligated to reimburse any
nonbreaching Buyer for the expenses described in Section 4(k) above.

            m. Placement Agent. The Company acknowledges that it has engaged one
or more placement agents in connection with the sale of the Debentures and the
Warrants and that the total amount of compensation of each such agent has been
disclosed in writing to each Buyer. Other than fees paid by Buyers, the Company
shall be responsible for the payment of any placement agent's fees, financial
advisory fees, or brokers' commissions (other than for persons engaged by any
Buyer or its investment advisor) relating to or arising out of the transactions
contemplated hereby. The Company shall pay, and hold each Buyer harmless
against, any liability, loss or expense (including, without limitation,
attorney's fees and out-of-pocket expenses) arising in connection with any such
claim.

            n. No Strict Construction. The language used in this Agreement will
be deemed to be the language chosen by the parties to express their mutual
intent, and no rules of strict construction will be applied against any party.

                                       32
<PAGE>

            o. Remedies. Each Buyer and each holder of the Securities shall have
all rights and remedies set forth in the Transaction Documents and all rights
and remedies which such holders have been granted at any time under any other
agreement or contract and all of the rights which such holders have under any
law. Any person having any rights under any provision of this Agreement shall be
entitled to enforce such rights to recover damages by reason of any breach of
any provision of this Agreement and to exercise all other rights granted by law.
Furthermore, the Company recognizes that in the event that it fails to perform,
observe, or discharge any or all of its obligations under this Agreement, any
remedy at law may prove to be inadequate relief to the Buyers. The Company
therefore agrees that the Buyers shall be entitled to seek temporary and
permanent injunctive relief in any such case without the necessity of proving
actual damages and without posting a bond or other security. The Company also
acknowledges that the Buyers can keep as security for the Company's obligations
under the Securities all funds advanced by the Company as defeasance payments
under the March Securities and under the July Securities.

            p. Payment Set Aside. To the extent that the Company makes a payment
or payments to any Buyer hereunder or pursuant to any of the other Transaction
Documents, or the Buyers enforce or exercise their rights hereunder or
thereunder, and such payment or payments or the proceeds of such enforcement or
exercise or any part thereof are subsequently invalidated, declared to be
fraudulent or preferential, set aside, recovered from, disgorged by or are
required to be refunded, repaid or otherwise restored to the Company, a trustee,
receiver or any other person under any law (including, without limitation, any
bankruptcy law, state or federal law, common law or equitable cause of action),
then to the extent of any such restoration the obligation or part thereof
originally intended to be satisfied shall be revived and continued in full force
and effect as if such payment had not been made or such enforcement or setoff
had not occurred.

            q. Independent Nature of Purchasers' Obligations and Rights. The
obligations of each Buyer under any of the Transaction Documents are several and
not joint with the obligations of any other Buyer, and no Buyer shall be
responsible in any way for the performance of the obligations of any other Buyer
under any of the Transaction Documents. Nothing contained herein or in any other
Agreement, and no action taken by any Buyer pursuant hereto or thereto, shall be
deemed to constitute the Buyers as a partnership, an association, a joint
venture or any other kind of entity, or create a presumption that the Buyers are
in any way acting in concert or as a group with respect to such obligations or
the transactions contemplated by the Transaction Documents. Each Buyer confirms
that it has independently participated in the negotiation of the transactions
contemplated hereby and the other Transaction Documents with the advice of its
own counsel and advisors. Each Buyer shall be entitled to independently protect
and enforce its rights, including, without limitation, the rights arising out of
this Agreement or out of any other Transaction Document, and it shall not be
necessary for any other Buyer to be joined as an additional party in any
proceeding for such purpose.

                            [signature page follows]

                                       33
<PAGE>

            IN WITNESS WHEREOF, the Buyers and the Company have caused this
Securities Purchase Agreement to be duly executed as of the date first written
above.

COMPANY:

HEMISPHERX BIOPHARMA, INC.

By:
   -----------------------------
Name:
Title:

                                     BUYERS:

                                     PORTSIDE GROWTH & OPPORTUNITY FUND

                                     By:
                                        ----------------------------------------
                                     Name:
                                          --------------------------------------
                                     Title:
                                           -------------------------------------

                                     LEONARDO, L.P.

                                     By:
                                        ----------------------------------------
                                     Name:
                                          --------------------------------------
                                     Title:
                                           -------------------------------------

                                       34
<PAGE>

                               SCHEDULE OF BUYERS

Debentures and Warrants:

<TABLE>
<CAPTION>

                                                      Aggregate
                                          Principal   Purchase                                                  Investor's
                                           Amount      Price of                    First         Second       Representatives'
Investor         Investor Address            of      Debentures    Number of      Payment        Payment          Address
  Name         and Facsimile Number      Debentures  and Warrants   Warrants       Amount        Amount      and Facsimile Number
--------       --------------------      ----------  ------------   --------      -------        -------     --------------------
<S>           <C>                          <C>          <C>           <C>         <C>            <C>
Portside      c/o Ramius Capital           $2,071,179   $1,775,000    205,067     $1,000,000     $775,000      Schulte Roth
Growth &      Group, L.L.C.                                                                                    & Zabel LLP
Opportunity   666 Third Avenue, 26th                                                                           919 Third Avenue
Fund          Floor                                                                                            New York, NY 10022
              New York, NY 10017                                                                               Attn: Eleazer
              Attention:  Jeffrey Smith                                                                        Klein, Esq.
                          Andrew Strober                                                                       Telephone:
                                                                                                               (212) 756-2000
              Telephone: (212) 845-7955                                                                        Facsimile:
              Facsimile: (212) 845-7999                                                                        (212)593-5955
              Residence: Cayman Islands

              c/o Angelo Gordon, LP
Leonardo      245 Park Avenue              $2,071,179   $1,775,000    205,067     $1,000,000     $775,000      Paul, Weiss,
L.P.          New York, NY 10167                                                                               Rifkind, Wharton
              Attention:  Fred Berger                                                                          & Garrison LLP
                                Gary Wolf                                                                      1285 Avenue
              Telephone:  (212) 692-2000                                                                       of the Americas
              Facsimile:   (212) 867-6449                                                                      New York, NY 10019
              Residence:  Cayman Islands                                                                       Attention: Jaideep
                                                                                                               P. Reddy, Esq.
                                                                                                               Telephone:
                                                                                                               (212) 373-3000
                                                                                                               Facsimile:
                                                                                                               (212) 757-3990
</TABLE>

<PAGE>

                             INDEX OF DEFINED TERMS

19.99% Rule....................................................................7
1933 Act.......................................................................1
1934 Act.......................................................................9
Account Control Agreement.....................................................21
Agent.........................................................................20
Agreement......................................................................1
AMEX..........................................................................15
Business Day...................................................................2
Buyer..........................................................................1
Buyer's Purchase Price.........................................................2
Bylaws.........................................................................8
Cash Collateral Account.......................................................20
Cash Collateral Bank..........................................................20
Certificate of Incorporation...................................................8
Change in Law.................................................................17
Closing........................................................................2
Closing Date...................................................................2
Code..........................................................................17
Collateral....................................................................22
Common Stock...................................................................1
Company........................................................................1
Conversion Shares..............................................................1
Debentures.....................................................................1
Environmental Laws............................................................12
Form 8-K......................................................................16
Hazardous Materials...........................................................12
Indemnified Liabilities.......................................................28
Indemnitees...................................................................27
Intellectual Property.........................................................11
Interferon Agreements.........................................................23
Interferon Asset Agreement....................................................23
Interferon Inventory and License Agreement....................................23
Irrevocable Transfer Agent Instructions.......................................24
Letter of Credit..............................................................20
Material Adverse Effect........................................................6
Minimum Rating................................................................20
Moody's.......................................................................20
Mortgage......................................................................22
Mortgages.....................................................................22
NASDAQ........................................................................15
Non-U.S. Debenture Holder.....................................................18
Non-U.S. Equity Holder........................................................18
NYSE..........................................................................15
Payment Date...................................................................2
Permits.......................................................................13

<PAGE>

Personal Property Collateral..................................................21
Phase I ESA...................................................................22
Phase II ESA..................................................................22
Principal Market..............................................................15
Properties....................................................................21
Real Property Collateral......................................................22
Registration Rights Agreement..................................................1
Regulation D...................................................................1
Reporting Period..............................................................15
Resolutions...................................................................27
S&P...........................................................................20
SEC............................................................................1
SEC Documents..................................................................9
Securities.....................................................................3
Security Agreement............................................................21
Segregated Account.............................................................2
Seller........................................................................22
Stockholder Approval..........................................................16
Stockholder Meeting Deadline..................................................16
Subsidiaries...................................................................6
Survey........................................................................22
Taxes.........................................................................17
Title Insurance Policy........................................................22
Transaction Documents..........................................................6
Warrant Shares.................................................................1
Warrants.......................................................................1

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