1. (18) Multiple choice questions. Please place your answer on the line preceding each question.

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1 CEM 5720 ame KEY Exam 2 ctober 21, 2015 Read all questions carefully and attempt those questions you are sure of first. Remember to proof your work; art work carries as much importance as written responses. Look over the entire exam before you begin. GD LUCK!! 1. (18) Multiple choice questions. Please place your answer on the line preceding each question. C Which of the following statements is true? a. A positive value of π indicates that a substituent is larger than hydrogen b. A positive value of π indicates that a substituent is more electron donating than hydrogen c. A positive value of π indicates that a substituent is more hydrophobic than hydrogen d. A negative value of π indicates that a substituent is more hydrophobic than hydrogen C Which of the following defines a structure which can be used as the starting point for drug design and development? a. Active principle b. Pharmacophore c. Lead compound d. rphan drug D From which source did the lead compound for the antiulcer agent cimetidine come from? a. Marine sources b. Venoms and toxins c. Combinatorial chemistry d. An endogenous compound B ydrogen is often replaced in drugs with a fluorine atom for a variety of reasons. What term is used to describe the fluorine atom when it is used to replace hydrogen? a. Isotope b. Isostere c. Isomer d. Isobar C Which of the following physicochemical properties is least commonly considered in QSAR studies? a. ydrophobicity b. Electronic influence of substituents c. Dipole moment d. Size of substituents C The simplification strategy is commonly used in drug design. What must be retained in a molecule during the simplification process to keep the biological activity? a. The molecular weight b. The stereochemistry c. The pharmacophore d. The hydrophobic character

2 2. (24) Three of the best selling drugs for 2010 in the United States are shown below. Determine which of the compounds, if any, violate Lipinski s rules. Log P values are given from online at oxycodone (xycontin) analgesic C 3 M.W. = Log P = 1.04 & = 2 's&'s=5 Violates Lipinski's Rules YES S M.W. = Log P = 1.66 & = 1 esomeprazole (exium) antiacid reflux 's&'s=6 Violates Lipinski's Rules YES 3 C Ac C 3 C 3 C 3 Bz Ac M.W. = Log P = 3.54 & = 4 's&'s=14 Taxol Violates Lipinski's Rules YES f the top 10 best selling drugs of 2010, GSK s Advair, an inhaled asthma medication, could not be used in the above question. Why was this drug left out of the Lipinski analysis? Because the Lipinski analysis describes characteristics that are for oral medications and Advair would be absorbed through the lungs and not in the gastrointestinal tract.

3 3. (20) In a recent article (J. d. Chem. 2009, 52, ) the authors explored the development of a potent agonist for the histamine 4 receptor subtype. The 4 receptor subtype has been shown to play a critical role in immunological and inflammatory processes. The goal of the research was to develop a compound that was selective for the 4 subtype over the 2 and 3 receptors. A. Define agonist. A molecule that produces a biological response or action, B. The following scheme depicts the molecules that were produced in the development process. For each indicated step suggest what common modification process was used to arrive at the shown structure. 1 2 C C 3 4 C S 1. omologation 2. Isosteric replacement 3. omologation 4. Isosteric replacement C. From the table of isosteres suggest another possible replacement for the sulfur atom in the final compound shown above Se-

4 4. (12) Captopril is an ACE inhibitor used in the treatment of high blood pressure. Based on the data in the following table, suggest two additional analogs that should be synthesized and screened. ote the larger the K i value the better the analog. STRUCTURE RELATIVE K i S captopril C 2 1 analog 1 S S 12,500 S C 2 S C C 2 S S C 2 12, analog 2 2 C C 2 S C 2 C C S C 2 2 C 1,100 C 2 C 2 5. (12) Use the partial list of Log P values at the end of the exam to calculate the log P ibuprofen. For full credit show all your work. branching C =1.41 C 3 C C 3 C Ibuprofen Log P = (2 x C3 )+ C + C2 + (branching) + PhC2C + C3 + (branching) Log P = (2 x 0.50) (-0.20) (-0.20) Log P = 3.51

5 6. (16) Carbonic anhydrases are ubiquitous zinc enzymes present in biological systems. These enzymes catalyze the interconversion between carbon dioxide and bicarbonate. f the approximately thirty compounds in clinical development as carbonic anhydrase inhibitors each compound contains a sulfonamide functional group (-S 2 2 ) that is responsible for binding to the zinc atom in the enzyme. Substituted sulfonamides exist in equilibrium between the protonated and deprotonated state shown below. A model of the zinc binding site for carbonic anhydrase is shown below. It contains a zinc (II) atom coordinated to three histidine residues on the protein chain and a fourth site that binds the natural substrates (carbon dioxide or bicarbonate) as well as the sulfonamide inhibitors. Which of the two structures in the above equilibria should be the better inhibitor of carbonic anhydrase? (Draw the chemical structure) Binding site is 94 is119 Zn 2+ is 96 X S 2 2 The binding site is a Lewis acid (positively charged) and would bindtothelonepaironthe sulfonamide nitrogen. The protonated sulfonamide would be repelled by the zinc. f the sixteen carbonic anhydrase isozymes (enzyme forms) found in mammals four of them are membrane bound. Using the table of sigma values ( ) what single group would you incorporate on the aromatic ring of the sulfonamide in order to enhance both binding to the zinc atom and penetration of the lipophilic membrane? (Draw the chemical structure) In mammals there are also five isozymes that are cytosolic existing in the aqueous portion of cellular fluids. Using the table of sigma values ( ) draw the structure of a disubstituted sulfonamide that would strongly bind the zinc atom at the sulfonamide, not enter the membrane, and minimize promiscuous binding at the zinc atom by the substituent. Using the table of sigma values ( ) what single group would you incorporate on the aromatic ring of the sulfonamide to produce a compound that was inactive as a carbonic anhydrase inhibitor? (Draw the chemical structure) S 2 2