<PAGE>
                                                                     EXHIBIT 4.2

          THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN
 REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED. THESE SECURITIES MAY
   NOT BE OFFERED OR SOLD IN THE ABSENCE OF SUCH REGISTRATION OR AN EXEMPTION
                       FROM REGISTRATION UNDER SUCH ACT.

                                125,000 Warrants

                           VOID AFTER AUGUST 13, 2007

                        WARRANT CERTIFICATE FOR PURCHASE
                                 OF COMMON STOCK

                                 EXEGENICS, INC.

      This certifies that FOR VALUE RECEIVED Roan Meyers Associates, L.P., or
its registered assigns (the "Registered Holder"), is entitled to subscribe for
and purchase from eXegenics, Inc., a Delaware corporation (the "Company"), upon
the terms and conditions set forth herein, at any time, or from time to time,
during the Exercise Period (as hereinafter defined), up to 125,000 shares of the
Company's Common Stock, par value $.01 par value per share (the "Common Stock").
The Warrant Shares (as hereinafter defined) shall be issuable at a price per
share of FIFTY-FIVE CENTS ($0.55) per share, as may be adjusted (such payment,
the "Exercise Price") in lawful money of the United States of America.

      As used herein, the term "this Warrant" or "this Warrant Certificate"
shall mean and include this Warrant and any Warrants hereafter issued as a
consequence of the exercise or transfer of this Warrant in whole or in part. The
number of-shares issuable upon exercise of this Warrant (the "Warrant Shares")
and the Exercise Price may be adjusted from time to time as hereinafter set
forth.

      As used herein, the term "Exercise Period" shall mean the period of time
from and after the date hereof until 5:00 P.M. (New York time) on the earlier of
(a) the Termination Date (as hereinafter defined), and (b) August 13, 2007;
provided, that, if either such date shall in the State of New York be a holiday
or a day on which the banks are authorized to close, then the next following day
which, in the State of New York, is not a holiday or a day on which banks are
authorized to close.

      l. Exercise.

            1.1 In General. This Warrant may be exercised during the Exercise
Period, at the option of the Registered Holder, as to the whole or any lesser
number of whole Warrant Shares, by surrender of this Warrant with a completed
Election of Exercise (in the form at the end hereof duly executed) to the
Company at its principal corporate offices or at such other place as is
designated in writing by the Company, together with a certified or bank
cashier's check payable to the order of eXegenics, Inc. in an amount equal to
the Exercise Price multiplied by the number of Warrant Shares for which his
Warrant is then being exercised (such amount, the "Purchase Price").

            1.2 Cashless Exercise. All or any portion of the Purchase Price may
be paid by surrender of this Warrant with a completed Election of Cashless
Exercise (in the form at the end hereof duly executed) to the Company at its
principal corporate offices or at such other place as is designated in writing
by the Company, which election of cashless exercise will instruct the Company to
deduct from the number of Warrant Shares otherwise deliverable upon such
exercise to the Registered Holder such number of Warrant Shares as is equal to
such Purchase Price or portion thereof all as more fully described below (a
"Cashless Exercise"). Such presentation and surrender shall be deemed a waiver
by the Company of the Registered Holder's obligation to pay all or such portion
of the aggregate Purchase Price as to which the Cashless Exercise relates. In
the event of a Cashless Exercise, the Company will deliver to the Registered

<PAGE>
Holder that number of Warrant Shares determined by multiplying the number of
Warrant Shares for which the Registered Holder desires to exercise this Warrant
by a fraction, the numerator of which shall be the difference between the then
current market price per share of the Common Stock and the Exercise Price, and
the denominator of which shall be the then current market price per share of
Common Stock. For purposes of any computation under this Warrant, the then
"current market price" per share of Common Stock at any date shall be deemed to
be the average for the ten consecutive business days immediately prior to the
Cashless Exercise of the daily closing prices of the Common Stock on the
principal national securities exchange on which the Common Stock is admitted to
trading or listed, or if not listed or admitted to trading on any such exchange,
the closing prices as reported by the Nasdaq National Market, or if not then
listed on the Nasdaq National Market, the average of the highest reported bid
and lowest reported asked prices as reported by the National Association of
Securities Dealers, Inc. Automated Quotations System ("Nasdaq") or if not then
publicly traded, the fair market price of the Common Stock as determined by the
Board of Directors of the Company.

            1.3 Issuance of Certificates. Each exercise of this Warrant shall be
deemed effective immediately prior to the close of business on the day on which
the last of the actions required for exercise under Section 1.1 or Section 1.2,
as applicable, has been satisfied. As soon as practicable after each such
exercise of this Warrant (whether pursuant to Section 1.1 or Section 1.2), the
Company shall issue and deliver to the Registered Holder a certificate or
certificates for the Warrant Shares issuable upon such exercise, registered in
the name of the Registered Holder or his or its designee. If this Warrant should
be exercised in part only, the Company shall, upon surrender of this Warrant for
cancellation, execute and deliver a new warrant evidencing the right of the
Registered Holder to purchase the balance of the Warrant Shares (or portions
thereof) subject to purchase hereunder. Notwithstanding anything contained
herein to the contrary, the Company may delay issuance of Warrant Shares until
completion of any action or execution of any instrument which the Company deems
necessary under applicable law, including, without limitation, Federal and State
securities laws.

      2. Certain Adjustments. The Exercise Price in effect at any time and the
number and kind of securities purchasable upon the exercise of this Warrant
shall be subject to adjustment from time to time upon the happening of certain
events.

            2.1 Changes in Common Stock. In case the Company shall at any time
during the Exercise Period (i) declare a dividend or make a distribution on its
outstanding shares of Common Stock in shares of Common Stock, (ii) subdivide or
reclassify its outstanding shares of Common Stock into a greater number of
shares, or (iii) combine or reclassify its outstanding shares of Common Stock
into a smaller number of shares, the Exercise Price in effect at the time of the
record date for such dividend or distribution or on the effective date of such
subdivision, combination or reclassification shall be adjusted so that it shall
equal the price determined by multiplying the Exercise Price by a fraction, the
denominator of which shall be the number of shares of Common Stock outstanding
after giving effect to such action, and the numerator of which shall be the
number of shares of Common Stock outstanding immediately prior to such action.
Such adjustment shall be made successively whenever any event listed above shall
occur and shall become effective on the record date for the determination of
stockholders entitled to receive such dividend or distribution or on the
effective date of such subdivision, combination or reclassification, as
applicable.

            2.2 Adjustments for Reclassification, Exchange and Substitution. If
the Warrant Shares issuable upon exercise of this Warrant shall be changed into
the same or a different number of shares of any other class or classes of stock,
whether by capital reorganization, reclassification or otherwise (other than a
subdivision or combination of shares which is provided for under Section 2.1
above and other than a reclassification in connection with a merger,
consolidation or sale which is provided for under Section 3 below) this Warrant
shall thereafter be exercisable into solely the kind and amount of shares of
such other class or classes of stock as to which such Registered Holder would
have received upon such reorganization, reclassification or other change had
such Registered Holder exercised this Warrant in full immediately prior to such
reorganization, reclassification or other change. Such adjustment shall be made
successively whenever any event listed above shall occur and shall become
effective on the effective date of such reorganization, reclassification or
other event.
<PAGE>
            2.3 Other Adjustments. Upon each adjustment of the Exercise Price as
a result of the calculations made in this Section 2, this Warrant shall
thereafter evidence the right to purchase, at the adjusted Exercise Price, that
number of shares (calculated to the nearest hundredth) obtained by dividing (A)
the product obtained by multiplying the number of shares purchasable upon
exercise of this Warrant prior to adjustment of the number of shares by the
Exercise Price in effect prior to adjustment of the Exercise Price, by (B) the
Exercise Price in effect after such adjustment of the Exercise Price.

            2.4 No Fractional Shares. The Company shall not be required to issue
fractions of shares of Common Stock or other capital stock of the Company upon
the exercise or conversion of this Warrant. If any fraction of a share would be
issuable on the exercise or conversion of this Warrant (or specified portions
thereof), the Company shall purchase such fraction for an amount in cash equal
to the same fraction of the current market price of such share of Common Stock
on the date of exercise or conversion of this Warrant.

      3. Consolidations, Mergers and Sales. If there shall be a merger or
consolidation of the Company with or into another corporation (other than a
merger or reorganization involving only a change in the state of incorporation
of the Company or a merger or reorganization in which the Company is the
surviving or continuing entity), or the sale of all or substantially all of the
Company's capital stock or assets to any other person, or the liquidation or
dissolution of the Company, then as a part of such transaction, at the Company's
option, either:

            (a) provision shall be made so that the Registered Holder shall
thereafter be entitled to receive upon exercise of this Warrant solely the kind
and amount of shares of stock or other securities or property of the Company, or
of the successor corporation resulting from the merger, consolidation or sale,
to which the Registered Holder would have been entitled if the Registered Holder
had exercised its rights pursuant to the Warrant immediately prior thereto (and,
thereafter, appropriate provision shall be made for adjustments which shall be
as nearly equivalent as practicable to the adjustments in Section 2); or

            (b) this Warrant shall terminate, and become null and void, at 5:00
P.M. (New York Time) on the business day immediately preceding the effective
date of such merger, consolidation or sale (the "Termination Date"); provided,
that if this Warrant shall not have otherwise terminated or expired, the Company
shall have given the Registered Holder written notice of such Termination Date
at least twenty (20) business days prior to the occurrence thereof.

         4.       Registration Rights.

            4.1 No Prior Registration. The Registered Holder acknowledges that
this Warrant and the Warrant Shares have not been registered under the
Securities Act of 1933, as amended, and the rules and regulations thereunder, or
any successor legislation (the "Securities Act"), and agrees not to sell,
pledge, distribute, offer for sale, transfer or otherwise dispose of this
Warrant or any Warrant Shares in the absence of (i) an effective registration
statement under the Securities Act covering the resale of this Warrant or such
Warrant Shares and registration or qualification of this Warrant or such Warrant
Shares under any applicable "blue sky" or state securities law then in effect,
or (ii) an opinion of counsel, satisfactory to the Company, that such
registration and qualification are not required. The Company may delay issuance
of the Warrant Shares until completion of any action or obtaining of any
consent, which the Company deems necessary under any applicable law (including,
without limitation, state securities or "blue sky" laws).

            4.2 S-3 Registration Rights. At any one time during the Exercise
Period and provided that the Company is then a registrant eligible to use Form
S-3, the Registered Holder shall have the right to request that the Company
prepare and file with the Securities and Exchange Commission (the "SEC") a
Registration Statement on Form S-3 covering the resale of all or any portion of
the Warrant Shares; provided, that the Warrant Shares to be included in any
Registration Statement pursuant to this Section 4.2 shall have a minimum
aggregate offering price to the public of at least $75,000, such registration
relate to at least 100,000 shares of Common Stock (which condition may be met by
aggregating


<PAGE>
the Warrant Shares of the Registered Holder with those of other persons having
registration rights or otherwise participating in such registration), and the
Registered Holder shall have the right to request only one registration under
this Section 4.2

            4.3 Registration Procedures. Any request for registration pursuant
to Section 4.2 shall be made in writing (a "Registration Notice") and shall set
forth the number of Warrant Shares requested to be so registered and the
Registered Holder's preferred method of distribution of such Warrant Shares.
Subject to the other provisions of this Section 4, the Company shall use its
commercially reasonable efforts to (a) prepare and file with the SEC a
Registration Statement covering the resale of such Warrant Shares, (b) cause
such Registration Statement to become effective as soon as practicable
thereafter, and (c) keep such Registration Statement continually effective until
the earlier of (i) such time as all Warrant Shares covered thereby are sold, and
(ii) the date which is 180 days following the effective date of the Registration
Statement.

            4.4 Permitted Delays. The Company shall be entitled to postpone the
filing of any Registration Statement, if (i) at any time prior to the filing of
such Registration Statement the Company determines, in its reasonable business
judgment, that such registration and offering could adversely affect any
financing, acquisition, corporate reorganization, or other material transaction
or development involving the Company or any of its affiliates, and (ii) the
Company gives the Registered Holder written notice of such postponement. In the
event of such postponement, the Company shall file such Registration Statement
as soon as practicable after it shall determine, in its reasonable business
judgment, that such registration and offering will not adversely effect the
matters described in the first sentence of this Section 4.4.

            4.5 Expenses. All expenses incurred in connection with a
registration pursuant to this Section 4 (other underwriting discounts and
commissions, if any, fees and disbursements of counsel for the Registered
Holder, and transfer taxes) shall be borne by the Company, provided that the
Company shall not be required to obtain a special audit of its financial
statements in connection with such registration statement.

            4.6 Cooperation. The Registered Holder agrees to cooperate with the
Company in connection with the preparation and filing of any Registration
Statement hereunder, and for so long as the Company is obligated to keep any
such Registration Statement effective, will provide to the Company, in writing,
for use in the Registration Statement, all information as may be necessary to
enable the Company to prepare the Registration and prospectus covering the
Warrant Shares and to maintain the currency and effectiveness thereof.

            4.7 Suspension of Offering or Distribution. On notice from the
Company of (i) the happening of any event as a result of which the prospectus
included in a Registration Statement, as then in effect, includes an untrue
statement of a material fact or fails to state a material fact required to be
stated therein or necessary to make the statements therein not misleading, (ii)
the issuance by the SEC of a stop order relating to a Registration Statement
covering the resale of Warrant Shares, the Registered Holder shall cease
offering or distributing the Warrant Shares until such time as the Company
notifies the Registered Holder that offering and distribution of the Warrant
Shares may recommence.

            4.8 Limitations. Notwithstanding anything in this Warrant to the
contrary, Company shall be under no obligation to file a registration statement
for the registration of the Warrant Shares if any of such Warrant Shares may
then be sold by the Registered Holder to the public pursuant to Rule 144 or
otherwise without registration.

      5. Exchange and Transferability Replacement. This Warrant Certificate is
exchangeable, upon the surrender hereof by the Registered Holder at the
corporate office of the Company, or at such other place as the Company may
designate, for a new Warrant Certificate or Warrant Certificates of like tenor
representing an equal aggregate number of Warrant Shares, each of such new
Warrant Certificates to represent such number of Warrant Shares as shall be
designated by such Registered Holder at the time of such surrender.
Notwithstanding the foregoing, the Company shall have no obligation to cause
this Warrant
<PAGE>
to be transferred on its books to any person if, in the opinion of counsel to
the Company, such transfer does not comply with the provisions of the Securities
Act. Without the prior written consent of the Company, this Warrant shall not be
assigned, pledged or hypothecated in any way, whether by operation of law or
otherwise (other than by will or pursuant to the laws of descent and
distribution) and shall not be subject to execution, attachment or similar
process. Any attempted transfer, assignment, pledge, hypothecation or other
disposition of the Warrant or of any rights granted hereunder contrary to the
provisions of this Section 5, or the levy of any attachment or similar process
upon this Warrant or such rights, shall be null and void. Upon receipt of
evidence satisfactory to the Company of the loss, theft, destruction, or
mutilation of this Warrant (and upon surrender of this Warrant if mutilated),
and upon reimbursement of the Company's reasonable incidental expenses, the
Company shall execute and deliver to the Registered Holder thereof a new Warrant
of like date, tenor, and denomination.

      6. No Rights as Stockholders. Prior to the exercise of this Warrant, the
Registered Holder shall not be entitled, solely on account of this Warrant, to
any rights of a stockholder of the Company, including, without limitation, the
right to vote or to receive dividends or other distributions, and shall not be
entitled to receive any notice of any proceedings of the Company.

      7. Taxes. The issuance of any shares or other securities upon the exercise
or conversion of this Warrant, and the delivery of certificates or other
instruments representing such shares or other securities, shall be made without
charge to the Registered Holder for any tax or other charge in respect of such
issuance. The Company shall not, however, be required to pay any tax which may
be payable in respect of any transfer involved in the issue and delivery of any
certificate in a name other than that of the Registered Holder and the Company
shall not be required to issue or deliver any such certificate unless and until
the person or persons requesting the issue thereof shall have paid to the
Company the amount of such tax or shall have established to the satisfaction of
the Company that such tax has been paid.

      8. Legend. Unless the Warrant-Shares issued upon exercise of this Warrant
are registered for resale under the Securities Act, the certificate or
certificates evidencing such Warrant Shares shall bear the following legend:

"THE SHARES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN REGISTERED UNDER THE
SECURITIES ACT OF 1933, AS AMENDED. THESE SHARES MAY NOT BE OFFERED OR SOLD IN
THE ABSENCE OF SUCH REGISTRATION OR AN EXEMPTION FROM REGISTRATION UNDER SUCH
ACT."

      9. Waivers and Modifications. Any term or provision of this Warrant may be
waived only by written document executed by the party entitled to the benefits
of such terms or provisions. The terms and provisions of this Warrant may be
modified or amended only by written agreement executed by the parties hereto.

      10. Governing Law. This Warrant Certificate shall be governed by and
construed in accordance with the laws of the State of New York.


<PAGE>
         IN WITNESS WHEREOF, the Company has caused this Warrant Certificate to
be duly executed manually or in facsimile by two of its officers thereunto duly
authorized.

                                         EXEGENICS, INC.


Dated: August 13, 2002                   By:
                                             -----------------------------------
                                             Name:
                                             Title:


                                             By:
                                                 --------------------------
                                                 Name:
                                                 Secretary:

                                                  [SEAL]


<PAGE>
ELECTION OF EXERCISE
(To be completed and executed by Registered Holder to Exercise Warrant)

In accordance with Section 1.1 of the within Warrant Certificate, the
undersigned Registered Holder hereby irrevocably elects to exercise his, her or
its right to purchase _________________ Warrant Shares and, in connection
therewith, tenders payment in the aggregate amount of $_________, which amount
represents the number of Warrant Shares as to which the undersigned is electing
his, her or its right to purchase, multiplied by the Exercise Price (as defined
in said Warrant), as adjusted pursuant to Section 2 therein, if applicable. The
undersigned Registered Holder requests that certificates for such Warrant Shares
shall be issued in the name of:

-------------------------------------

-------------------------------------

-------------------------------------

-------------------------------------

(Print Name, Address and Social Security or
Tax Identification Number)

and, if such number of Warrant Shares shall not be all the Warrants Shares
evidenced by the within Warrant Certificate, that a new Warrant Certificate for
the balance of such Warrants be registered in the name of, and delivered to, the
Registered Holder at the address- stated below.

Date:
      -------------------------------       ------------------------------------
                                             (Print Name of Registered Holder)
Address of Registered Holder:
                                            ------------------------------------
                                            (Signature and Title, if applicable)

-------------------------------------

-------------------------------------

-------------------------------------


THE SIGNATURE ON THIS ELECTION TO EXERCISE FORM MUST CORRESPOND TO THE NAME AS
WRITTEN UPON THE FACE OF THIS WARRANT CERTIFICATE IN EVERY PARTICULAR, WITHOUT
ALTERATION OR ENLARGEMENT OR ANY CHANGE WHATSOEVER, AND MUST BE GUARANTEED BY A
COMMERCIAL BANK OR TRUST COMPANY OR A MEMBER FIRM OF THE AMERICAN STOCK
EXCHANGE, NEW YORK STOCK EXCHANGE, PACIFIC STOCK EXCHANGE OR MIDWEST STOCK
EXCHANGE.


<PAGE>
ASSIGNMENT
(To be completed and executed by the Registered Holder to transfer Warrant)


FOR VALUE RECEIVED, the undersigned Registered Holder hereby sells, assigns and
transfers unto:

-------------------------------------

-------------------------------------

-------------------------------------

-------------------------------------

(Print Name, Address and Social Security or Tax Identification Number)

the right to purchase ____________________ of the Warrants Shares represented by
the within Warrant Certificate, and hereby irrevocably constitutes and appoints
______________________ attorney-in-fact to transfer this Warrant Certificate on
the books of the Company, with full power of substitution in the premises, and,
if such number of Warrant Shares shall not be all the Warrants Shares evidenced
by the within Warrant Certificate, that a new Warrant Certificate for the
balance of such Warrants be registered in the name of, and delivered to, the
Registered Holder at the address stated below.

Date:
      -------------------------------       ------------------------------------
                                             (Print Name of Registered Holder)
Address of Registered Holder:
                                            ------------------------------------
                                            (Signature and Title, if applicable)


-------------------------------------

-------------------------------------

-------------------------------------



THE SIGNATURE ON THIS ASSIGNMENT FORM MUST CORRESPOND TO THE NAME AS WRITTEN
UPON THE FACE OF THIS WARRANT CERTIFICATE IN EVERY PARTICULAR, WITHOUT
ALTERATION OR ENLARGEMENT OR ANY CHANGE WHATSOEVER, AND MUST BE GUARANTEED BY A
COMMERCIAL BANK OR TRUST COMPANY OR A MEMBER FIRM OF THE AMERICAN STOCK
EXCHANGE, NEW YORK STOCK EXCHANGE, PACIFIC STOCK EXCHANGE OR MIDWEST STOCK
EXCHANGE.


<PAGE>
ELECTION OF CASHLESS EXERCISE
(To be completed and executed by Registered Holder to Exercise Warrant
pursuant to Cashless Exercise provisions)

In accordance with Section 1.2 of the within Warrant Certificate, the
undersigned Registered Holder hereby irrevocably elects to exercise his, her or
its right to purchase _________________ Warrant Shares and, in connection
therewith, directs that the payment of the purchase price for such Warrant
Shares be made pursuant to the cashless exercise provisions of the within
Warrant. The undersigned Registered Holder requests that certificates for such
Warrant Shares (less any Warrant Shares not delivered in accordance with such
cashless exercise provisions) shall be issued in the name of:

-------------------------------------

-------------------------------------

-------------------------------------

-------------------------------------


(Print Name, Address and Social Security
or Tax Identification Number)

and, if such number of Warrant Shares shall not be all the Warrants Shares
evidenced by the within Warrant Certificate, that a new Warrant Certificate for
the balance of such Warrants be registered in the name of, and delivered to, the
Registered Holder at the address stated below.

Date:
      -------------------------------       ------------------------------------
                                             (Print Name of Registered Holder)
Address of Registered Holder:
                                            ------------------------------------
                                            (Signature and Title, if applicable)


-------------------------------------

-------------------------------------

-------------------------------------


THE SIGNATURE ON THIS ELECTION OF CASHLESS EXERCISE FORM MUST CORRESPOND TO THE
NAME AS WRITTEN UPON THE FACE OF THIS WARRANT CERTIFICATE IN EVERY PARTICULAR,
WITHOUT ALTERATION OR ENLARGEMENT OR ANY CHANGE WHATSOEVER, AND MUST BE
GUARANTEED BY A COMMERCIAL BANK OR TRUST COMPANY OR A MEMBER FIRM OF THE
AMERICAN STOCK EXCHANGE, NEW YORK STOCK EXCHANGE, PACIFIC STOCK EXCHANGE OR
MIDWEST STOCK EXCHANGE.