Medicinal Chemistry — DU B. Sc. (Hons) Biomedical Previous Year Question Papers

Attempt five questions in all. Give illustrations and examples wherever required. (Subparts of the questions should be attempted together). • 1. (a) Briefly explain the following (any six) : 6×2=12 (iii) Pre-systemic metabolism (io) Topliss scheme (0) Scatchard plot (vii) Caffeine. (b) Distinguish between (any three) : 3x4=12 (i) Graded and Quantal Response (ii) Carrier-Linked Prodrug and Bioprecursor (io) Reversible and Irreversible Inhibitor (0) Drug tolerance and Drug dependence. (c) State whether the given statement is true or false. Justify your answer: (ii) Hydrophilicity of the drug is an important factor responsible for its poor absorption. 2. (i). Explain the mechanism of action of DNA-alkylating agents with the help of a diagram. Provide a suitable example of a DNA-alkylator drug. Also, discuss the key properties and clinical significance of DNA-alkylating agents. (i) Explain how GPCRs work with the help of a labelled diagram. (ii) What do target specificity and selectivity between species mean. ? Why are they important in finding and developing drug targets ? Explain how clavulanic acid acts a suicide substrate for bacterial beta-lactamase enzyme. Explain the importance of the double reciprocal plot in enzyme kinetics. Draw and compare the plots for competitive and non-competitive inhibition. 5,5,5 5. (i) What is a lead compound in drug discovery? Discuss the advantages and disadvantages of using natural compounds as sources of lead compounds. (i) Why is the levodopa-carbidopa combination preferred over dopamine for the treatment of Parkinson's disease ? Discuss the rationale behind this strategy. (iii) Discuss Rule of Five and its significance in drug discovery. 5,5,5