<PAGE>   1
                                                                   EXHIBIT 10.62


                               EMPLOYMENT CONTRACT

                                     between


DISCOVERY TECHNOLOGIES AG
Gewerbestrasse 16
4123 Allschwil
(hereinafter referred to as "DTL")

                                       and

DR. HEINRICH ZINSLI
Elblingstr. 10
4142 Munchenstein

(hereinafter referred to as "Employee")

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

WHEREAS, DTL has concluded an Employment Agreement with Dr. H. Zinsli on
February 19, 1999;

WHEREAS, Dr. H. Zinsli is a member of the management board and of the board of
directors;

WHEREAS, DTL desires to appoint Dr. H. Zinsli to the position of CEO.

NOW, THEREFORE, in consideration of the promises and mutual covenants herein set
forth, the parties conclude the following Agreement which overrides the
Employment Agreement dated February 19, 1999:

1.   Employment

     DTL hereby employs the Employee as CEO.

<PAGE>   2
                                                                             -2-

2.   Duration/Termination

     The Agreement shall become effective upon signature of both parties and
     shall be valid for a definite period of two (2) years and will terminate on
     July 31, 2001. Six months before the ending of the period of the two years,
     the parties inform each other if they are prepared to continue the
     Agreement.

     Upon mutual agreement of both parties the Agreement shall be automatically
     extended for an indefinite period until terminated by either party thereto
     giving, by registered letter, six months notice at the end of each month.

3.   Working Hours/Compensation for Overtime

     The Employee shall work 90% to 100% of the normal working hours which are
     for a full time position 40 hours a week. The Employee shall devote as much
     time, attention and ability as is reasonable to fulfill his duties. Besides
     the normal vacation mentioned in the Employment Policies
     ("Arbeitsreglement") the Employee is entitled to have five days extra for
     overtime work. Any compensation for overtime is deemed to be compensated by
     granting these extra days for overtime work and therefore, the Employee is
     not entitled to additional compensation for overtime.

4.   Salary

     The gross yearly salary will correspond to CHF 162,110 (in words: hundred
     and sixty two thousand one hundred and ten Swiss Francs). The salary shall
     be payable in 13 equal monthly installments of gross CHF 12,470 for a full
     time position (100%). The Employee's contribution to the Swiss social
     security scheme as prescribed by Swiss law and according to the
     "Arbeitsreglement" and his contribution to the collective health insurance
     (Krankentaggeldversicherung) will be deducted from his salary. The salary
     can be adjusted as per January 1 every year taking into consideration DTL's
     financial situation, any general price increase, the situation on the labor
     market and the individual performance and function of the Employee. The
     salary can be adjusted for the first time as per January 1, 2000.

     At the end of or during the year DTL may pay a discretionary bonus.
     However, previous bonus payments do not set the precedent. The payment and
     the amount of this bonus will always remain at the sole and absolute
     discretion of DTL.

<PAGE>   3
                                                                             -3-

5.   Other Compensation

     DTL pays in addition to the salary the following compensation:

     -    Bel Etage Insurance of CHF 40,000 annually (risk premium and savings
          premium);

     -    Board of director's fee of gross CHF 24,000 annually as long as he is
          a member of the board of directors of DTL. The social contributions as
          described by Swiss law are deducted from the board of director's fee:

     -    General Allowance of CHF 6,000 annually;

     -    Car allowance: CHF 800 monthly.

6.   Non Disclosure of Information

a)   The Employee agrees that he will not (except in the performance of his
     duties and as an employee of DTL) at any time or in any mariner make or
     cause to be made any copies, pictures, duplicates, facsimiles or other
     reproductions or recordings of any reports, studies, memoranda,
     correspondence, summaries thereof, or other written, printed or otherwise
     recorded materials, including but not limited to any magnetically recorded
     computer program or data, of any kind whatsoever belonging to or in the
     possession of DTL or customers of DTL. The Employee shall have no right,
     title or interest in or to any such material, and he agrees that (except in
     the performance of his duties as an employee of DTL) he will not, without
     DTL's prior written consent, remove any such Material from the premises of
     DTL, and that he will surrender all such materials to DTL immediately upon
     the termination of his employment with DTL or at any time prior thereto
     upon the request of DTL; provided however, that the foregoing does not
     apply to any such material not unique to DTL and the customers of DTL or
     that is otherwise available to the public other than as a result of his
     breach of this Agreement.

b)   The Employee covenants and agrees, without any limitation as to time, other
     than for purposes of carrying out DTL's duties in furtherance of its
     agreements with the customers, that:

     -    All information obtained by him during the course of performing
          services for DTL pursuant to the agreements between DTL and the
          customers of DTL shall be kept strictly confidential and he will not
          anywhere use for himself, or divulge any confidential or proprietary
          information with respect to DTL or any customer, including, but
          limited to, their businesses, operations, equipment and products, to
          any person, firm, corporation, association or any other entity for any
          reason whatsoever;

<PAGE>   4
                                                                             -4-

     -    he shall not furnish to or use for the benefit of any person, firm,
          corporation, association or any other entity any equipment or material
          or make use of any pursuant information received or developed through
          any existing and future agreements between DTL and its customers.

7.   Other Professional Activities

     The Employee is not allowed to pursue any professional activity for his own
     personal benefit or on account of a third party, unless he has received the
     prior formal consent of DTL.

8.   Penalty

     In case of violation of any provision in the Employment Agreement or of any
     directive of DTL the Employee shall pay a fixed penalty equaling CHF 50,000
     (fifty thousand Swiss Francs) for each infringement if he is not able or
     willing to provide remedy within a reasonable time as according to DTL.

     Notwithstanding payment of the penalty, DTL reserves the right to claim
     compensation for losses or damages, provided that such losses or damages
     exceed the amount of the penalty. Further, DTL expressly reserves the right
     to demand that the infringing activity be terminated immediately.

9.   Covenant against Competition

a)   Upon termination of this Agreement the Employee will abstain from entering
     into competition with DTL for a period of 1 (one) year. This non-compete
     clause is valid worldwide except in those jurisdictions where it cannot be
     enforced. The Employee will not perform work as an employee, an independent
     consultant or contractor for a company engaged in the same field of DTL nor
     shall he have share interests in companies working in that field.

b)   In case of violation of the above provision, the Employee shall pay DTL a
     fixed penalty equaling the last 6 monthly wages (inclusive 13th monthly
     installment and bonus payments) for each infringement. Notwithstanding
     payment of the penalty, DTL reserves the right to claim compensation for
     losses or damages, provided that such losses or damages exceed the amount
     of the penalty. Further, DTL expressly reserves the right to demand that
     the infringing activity be terminated immediately.

<PAGE>   5
                                                                             -5-

c)   The Covenant against Competition lapses according to Article 340c paragraph
     2 of the Swiss Code of Obligations if DTL terminates the Agreement without
     a valid reason. However, in the event DTL terminates the Agreement or the
     Employee terminates the Agreement for a valid reason for which DTL is
     responsible, the Covenant against Competition will continue throughout any
     time period that DTL is obliged to continue paying the Employee.

d)   The Covenant against Competition in this Agreement will in no event impact
     or nullify clause 9, non compete, mentioned in the Voting Share Purchase
     Agreement dated August 10, 1999 between Dr. Heinrich Zinsli, Dr. Ernst
     Burgisser, Dr. Helmut Kessmann, Christoph Grether and Discovery Partners
     International Inc.

10.  Miscellaneous

     The Employment Policies (Arbeitsreglement) are made a part of this
     Agreement.

11.  Governing Law

     THIS EMPLOYMENT CONTRACT WILL BE GOVERNED AND CONSTRUED IN ACCORDANCE WITH
     SWISS EMPLOYMENT LAW. VENUE SHALL BE ARLESHEIM.

Allschwil,        10/8/99                      Allschwil,     Aug 10/99
---------------------------                    ---------------------------------
Place and date                                 Place and date

DISCOVERY TECHNOLOGIES AG, ALLSCHWIL           EMPLOYEE
(EMPLOYER)

/s/  illegible                                 /s/  Dr. Heinrich Zinsli
---------------------------                    ---------------------------------
                                               Dr. Heinrich Zinsli