AMENDED AND RESTATED EXECUTIVE EMPLOYMENT AGREEMENT

Exhibit 10.6

AMENDED AND RESTATED
EXECUTIVE EMPLOYMENT AGREEMENT

     This Amended and Restated Employment Agreement (the “Agreement” ) is made and entered into effective as of November 7, 2008 (the “Effective Date” ), by and between Ardea Biosciences, Inc. , (the “Company” ), and Dr. Barry Quart (the “Executive” ). The Company and the Executive are hereinafter collectively referred to as the “Parties” , and individually referred to as a “Party” .

Recitals

      A.  The Company and the Executive are parties to that certain Executive Employment Agreement dated December 21, 2006 (the “Prior Agreement” ).

      B.  The Parties now desire to amend and restate the Prior Agreement and to continue the Parties’ employment relationship on the terms and conditions set forth below.

Agreement

     In consideration of the foregoing Recitals and the mutual promises and covenants herein contained, and for other good and valuable consideration, the Parties, intending to be legally bound, agree as follows:

      1. Employment.

           1.1 Title . The Executive shall initially have the title of President and Chief Executive Officer of the Company and shall serve in such other capacity or capacities as the Company may from time to time prescribe. The Executive shall initially report to the Board of Directors of the Company (the “ Board ” ).

           1.2 Duties. The Executive shall do and perform all services, acts or things necessary or advisable to manage and conduct the business of the Company and which are normally associated with the position of President and Chief Executive Officer, consistent with the bylaws of the Company and as required by the Board.

           1.3 Directorship. The Executive shall serve as a member of the Board, subject to election and reelection by the Company’s stockholders in accordance with the Company’s Certificate of Incorporation and Bylaws. The Executive shall devote such time to the business of the Company as is necessary for the fulfillment of the Executive’s duties as a member of the Board. The Executive shall not be paid a fee for serving as a member of the Board. The Company shall reimburse the Executive for reasonable expenses incurred in connection with his service as a member of the Board.

           1.4 Policies and Practices. The employment relationship between the Parties shall be governed by the policies and practices established by the Company and the Board. The Executive acknowledges that he has read the Company’s Employee Handbook and other governing policies, which will govern the terms and conditions of his employment with the Company, along with this Agreement. In the event that the terms of this Agreement differ from or are in conflict with the Company’s policies or practices or the Company’s Employee Handbook, this Agreement shall control.

           1.5 Location . Unless the Parties otherwise agree in writing, during the term of this Agreement, the Executive shall perform the services the Executive is required to perform pursuant to this Agreement at the Company’s offices, located in San Diego, California, or at any other place at which the

Company maintains an office; provided, however, that the Company may from time to time require the Executive to travel temporarily to other locations in connection with the Company’s business.

      2. Loyal and Conscientious Performance; Noncompetition.

           2.1 Loyalty . During the Executive’s employment by the Company, the Executive shall devote the Executive’s full business energies, interest, abilities and productive time to the proper and efficient performance of the Executive’s duties under this Agreement. Notwithstanding the foregoing, the Executive may continue to serve as a member of the Board of Directors of Trimeris, Inc. and Atherotope Incorporated and the Executive may provide occasional scientific consulting, including but not limited to Napo Pharmaceuticals, Inc., not to exceed twelve (12) hours per month to endeavors that are not competitive with the Company.

           2.2 Covenant not to Compete . Except with the prior written consent of the Company’s Board of Directors or the CEO, which shall not be unreasonably withheld, the Executive will not, during his employment by the Company, engage in competition with the Company and/or any of its Affiliates, either directly or indirectly, in any manner or capacity, as adviser, principal, agent, affiliate, promoter, partner, officer, director, employee, stockholder, owner, co-owner, consultant, or member of any association or otherwise, in any phase of the business of developing, manufacturing and marketing of products or services which are in the same field of use or which otherwise compete with the products or services or proposed products or services of the Company and/or any of its Affiliates. For purposes of this Agreement, “Affiliate” means, with respect to any specific entity, any other entity that, directly or indirectly, through one or more intermediaries, controls, is controlled by or is under common control with such specified entity.

           2.3 Agreement not to Participate in Company’s Competitors . During any period during which the Executive is receiving any compensation or consideration from the Company, the Executive agrees not to acquire, assume or participate in, directly or indirectly, any position, investment or interest known by the Executive to be adverse or antagonistic to the Company, its business or prospects, financial or otherwise or in any company, person or entity that is, directly or indirectly, in competition with the business of the Company or any of its Affiliates. Ownership by the Executive, as a passive investment, of less than two percent (2%) of the outstanding shares of capital stock of any corporation with one or more classes of its capital stock listed on a national securities exchange or publicly traded on the Nasdaq Stock Market or in the over-the-counter market shall not constitute a breach of this paragraph.

      3. Compensation of the Executive.

           3.1 Base Salary. The Company shall pay the Executive a base salary of Four Hundred Thousand Dollars ($400,000) per year, less payroll deductions and all required withholdings payable in regular periodic payments in accordance with Company policy. Such base salary shall be prorated for any partial year of employment on the basis of a 365-day fiscal year.

           3.2 Performance Bonus. In addition to the Executive’s base salary, the Executive shall be eligible for a performance bonus based upon the Executive’s and the Company’s achievement of specified objectives established by the Board during the first quarter of each year after consultation with the Executive, as evaluated by the Board in its discretion. The target bonus for full achievement of all objectives shall be fifty percent (50%) of the Executive’s Base Salary.

           3.3 Changes to Compensation. The Executive’s compensation will be reviewed on a regular basis by the Company and may be changed from time to time as deemed appropriate.

           3.4 Employment Taxes . All of the Executive’s compensation shall be subject to customary withholding taxes and any other employment taxes as are commonly required to be collected or withheld by the Company.

      4. Termination.

           4.1 Termination By the Company . The Executive’s employment by the Company shall be at will. The Executive’s employment with the Company may be terminated by the Company at any time and for any reason or no reason, with or without “Cause” (as defined below), subject to the provisions of this Section 4.

           4.2 Termination by Mutual Agreement of the Parties . The Executive’s employment pursuant to this Agreement may be terminated at any time upon a mutual agreement in writing of the Parties. Any such termination of employment shall have the consequences specified in such agreement.

           4.3 Termination by the Executive. The Executive’s employment by the Company shall be at will. The Executive shall have the right to resign or terminate the Executive’s employment at any time and for any reason, or no reason, with or without “Good Reason” (as defined below), subject to the provisions of this Section 4.

           4.4 Compensation Upon Termination.

                4.4.1 With Cause or Without Good Reason. If the Executive’s employment shall be terminated by the Company for Cause, or if the Executive terminates employment hereunder for other than Good Reason, the Company shall pay the Executive’s base salary and accrued and unused vacation benefits earned through the date of termination at the rate in effect at the time of termination, less standard deductions and withholdings, and the Company shall thereafter have no further obligations to the Executive under this Agreement.

                4.4.2 Without Cause or With Good Reason. If the Executive’s employment shall be terminated by the Company without Cause, or by the Executive for Good Reason, the Executive shall receive the payments specified in Section 4.4.1, and, in addition, within ten (10) days of the Executive’s delivery to the Company of a fully effective Release and Waiver in the form attached hereto as Exhibit A , within the applicable time period set forth therein, but in no event later than forty-five (45) days following termination of the Executive’s employment, the Executive shall receive the following: (i) a lump sum payment equal to the sum of the Executive’s annual base salary then in effect and the Executive’s target performance bonus then in effect, less required deductions and withholdings; (ii) accelerated vesting of shares subject to all stock awards, for the number of shares which would have vested accordingly had the Executive continued employment with the Company for a period of twelve (12) months after termination; and (iii) provided that the Executive timely elects continued coverage under the Consolidated Comprehensive Omnibus Budget Reconciliation Act of 1985 ( “COBRA” ), the COBRA benefit specified in Section 4(c) of the Company’s Senior Executive Severance Benefit Plan as it may be amended from time to time.

                4.4.3 Change in Control. The provisions of Article Two, Section IVB(i) and (ii) of the Company’s 2004 Stock Equity Incentive Plan (the “Plan” ) providing for acceleration of outstanding option rights in the event of a “Change in Control” (as defined in the Appendix, Section C, of the Plan) and an “Involuntary Termination” thereafter (as defined in the Plan) are hereby incorporated into this Agreement and shall apply in full.

               If the Executive’s employment shall be terminated by the Company without Cause, or by the Executive for Good Reason within three (3) months before or within twelve (12) months following a Change in Control, the Executive shall receive the payments specified in Section 4.4.1, and, in addition, within ten (10) days of the Executive’s delivery to the Company of a fully effective Release and Waiver in the form attached hereto as Exhibit A , within the applicable time period set forth therein, but in no event later than forty-five (45) days following termination of the Executive’s employment, the Executive shall receive the following: (i) a lump sum payment equal to one-hundred-fifty percent (150%) of the Executive’s annual base salary then in effect, less required deductions and withholdings; (ii) the greater of the Executive’s target performance bonus then in effect, less required deductions and withholdings, or the Executive’s target performance bonus paid in accordance with the year preceding the year in which termination occurs, less required deductions and withholdings; and (iii) provided that the Executive timely elects continued coverage under COBRA, the COBRA benefit specified in Section 4(c) of the Company’s Senior Executive Severance Benefit Plan as it may be amended from time to time, for a period of eighteen (18) months or, if shorter, for the duration of the COBRA continuation period.

                4.4.4 Parachute Payment. If any payment or benefit Executive would receive pursuant to a Change of Control or otherwise ( “Payment” ) would (i) constitute a “parachute payment” within the meaning of Section 280G of the Code, and (ii) but for this sentence, be subject to the excise tax imposed by Section 4999 of the Code (the “Excise Tax” ), then such Payment shall be reduced to the Reduced Amount. The “Reduced Amount” shall be either (x) the largest portion of the Payment that would result in no portion of the Payment being subject to the Excise Tax or (y) the largest portion, up to and including the total, of the Payment, whichever amount, after taking into account all applicable federal, state and local employment taxes, income taxes, and the Excise Tax (all computed at the highest applicable marginal rate), results in the Executive’s receipt, on an after-tax basis, of the greater amount of the Payment notwithstanding that all or some portion of the Payment may be subject to the Excise Tax. If a reduction in payments or benefits constituting “parachute payments” is necessary so that the Payment equals the Reduced Amount, reduction shall occur in the following order: reduction of cash payments; cancellation of accelerated vesting of stock awards; reduction of employee benefits. In the event that acceleration of vesting of stock award compensation is to be reduced, such acceleration of vesting shall be cancelled in the reverse order of the date of grant of Executive’s stock awards.

               The accounting firm engaged by the Company for general audit purposes as of the day prior to the effective date of the Change of Control shall perform the foregoing calculations. If the accounting firm so engaged by the Company is serving as accountant or auditor for the individual, entity or group effecting the Change of Control, then the Company shall appoint a nationally recognized accounting firm to make the determinations required hereunder. The Company shall bear all expenses with respect to the determinations by such accounting firm required to be made hereunder.

               The accounting firm engaged to make the determinations hereunder shall provide its calculations, together with detailed supporting documentation, to the Executive and the Company within fifteen (15) calendar days after the date on which the Executive’s right to a Payment is triggered (if requested at that time by the Executive or the Company) or such other time as requested by the Executive or the Company. If the accounting firm determines that no Excise Tax is payable with respect to a Payment, either before or after the application of the Reduced Amount, it shall furnish the Executive and the Company with an opinion reasonably acceptable to the Executive that no Excise Tax will be imposed with respect to such Payment. Any good faith determinations of the accounting firm made hereunder shall be final, binding and conclusive upon the Executive and the Company.

                4.4.5 Application of Section 409A . Notwithstanding anything to the contrary set forth herein, any payments and benefits provided under this Agreement (the “ Severance Benefits ”) that constitute “deferred compensation” within the meaning of Section 409A of the Internal Revenue Code of 1986, as amended (the “ Code ”) and the regulations and other guidance thereunder and any state law of similar effect (collectively “ Section 409A ”) shall not commence in connection with Executive’s termination of employment unless and until Executive has also incurred a “separation from service” (as such term is defined in Treasury Regulation Section 1.409A-1(h) (“ Separation From Service ”), unless the Company reasonably determines that such amounts may be provided to Executive without causing Executive to incur the additional 20% tax under Section 409A.

               It is intended that each installment of the Severance Benefits payments provided for in this Agreement is a separate “payment” for purposes of Treasury Regulation Section 1.409A-2(b)(2)(i). For the avoidance of doubt, it is intended that payments of the Severance Benefits set forth in this Agreement satisfy, to the greatest extent possible, the exemptions from the application of Section 409A provided under Treasury Regulation Sections 1.409A-1(b)(4), 1.409A-1(b)(5) and 1.409A-1(b)(9). However, if the Company (or, if applicable, the successor entity thereto) determines that the Severance Benefits constitute “deferred compensation” under Section 409A and Executive is, on the termination of Executive’s service, a “specified employee” of the Company or any successor entity thereto, as such term is defined in Section 409A(a)(2)(B)(i) of the Code, then, solely to the extent necessary to avoid the incurrence of the adverse personal tax consequences under Section 409A, the timing of the Severance Benefit payments shall be delayed until the earlier to occur of: (i) the date that is six months and one day after Executive’s Separation From Service or (ii) the date of Executive’s death (such applicable date, the “ Specified Employee Initial Payment Date ”), and the Company (or the successor entity thereto, as applicable) shall (A) pay to Executive a lump sum amount equal to the sum of the Severance Benefit payments that Executive would otherwise have received through the Specified Employee Initial Payment Date if the commencement of the payment of the Severance Benefits had not been so delayed pursuant to this Section and (B) commence paying the balance of the Severance Benefits in accordance with the applicable payment schedules set forth in this Agreement.

               Except to the extent that payments may be delayed until the Specified Employee Initial Payment Date pursuant to the preceding paragraph, on the first regular payroll pay day following the effective date of the Release, the Company will pay Executive the Severance Benefits Executive would otherwise have received under the Agreement on or prior to such date but for the delay in payment related to the effectiveness of the Release, with the balance of the Severance Benefits being paid as originally scheduled. All amounts payable under the Agreement will be subject to standard payroll taxes and deductions.

           4.5 Definitions.

                4.5.1 Cause. For purposes of this Agreement, “Cause” means that, in the reasonable determination of the Company, the Executive has:

                    (i) been indicted for or convicted of or pleaded guilty or no contest to any felony or crime involving dishonesty that is likely to inflict or has inflicted demonstrable and material injury on the business of the Company;

                    (ii) participated in any fraud against the Company;

                    (iii) willfully and materially breached a Company policy;

                    (iv) intentionally damaged any property of the Company thereby causing demonstrable and material injury to the business of the Company;

                    (v) willfully and materially breached the Executive’s Proprietary Information and Inventions Agreement with the Company; or

                    (vi) engaged in conduct that, in the reasonable determination of the Company, demonstrates gross unfitness to serve.

               Notwithstanding the foregoing, Cause shall not exist based on conduct described in clause (iii) or (vi) above unless the conduct described in such clause has not been cured within fifteen (15) days following the Executive’s receipt of written notice from the Company specifying the particulars of the conduct constituting Cause.

                4.5.2 Good Reason. “Good Reason” for the Executive to terminate the Executive’s employment hereunder shall mean the occurrence of any of the following events without the Executive’s consent; provided however, that any resignation by the Executive due to any of the following conditions shall only be deemed for Good Reason if: (i) the Executive gives the Company written notice of the intent to terminate for Good Reason within ninety (90) days following the first occurrence of the condition(s) that the Executive believes constitutes Good Reason, which notice shall describe such condition(s); (ii) the Company fails to remedy, if remediable, such condition(s) within thirty (30) days following receipt of the written notice (the “Cure Period” ) of such condition(s) from the Executive; and (iii) Executive actually resigns his employment within the first fifteen (15) days after expiration of the Cure Period.

                    (i) a material reduction by the Company of the Executive’s Base Salary as initially set forth herein or as the same may be increased from time to time;

       &