JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B. Pharmacy IV Year MEDICINAL CHEMISTRY - II Previous Question Paper (July-2021 - R17)
Answer any five questions
All questions carry equal marks
Main
Classify histamine receptors and mention their distribution in the body. Describe the synthesis of Triprolidine hydrochloride.
Answer
Histamine receptors are G-protein coupled receptors (GPCRs) classified into four main subtypes based on their pharmacological properties and signaling mechanisms:
- H1 receptors: Primarily distributed in smooth muscles (bronchi, gastrointestinal tract), vascular endothelium, and the central nervous system. Activation leads to vasodilation, bronchoconstriction, and increased capillary permeability.
- H2 receptors: Located mainly in gastric parietal cells, cardiac muscle, and vascular smooth muscle. They are primarily responsible for stimulating gastric acid secretion.
- H3 receptors: Found predominantly in the central nervous system and peripheral nerve endings. They act as presynaptic autoreceptors to inhibit the release of histamine and other neurotransmitters.
- H4 receptors: Primarily expressed in hematopoietic cells, including eosinophils, neutrophils, and mast cells. They play a significant role in chemotaxis and inflammatory responses.
Triprolidine hydrochloride is a first-generation antihistamine synthesized via the following steps:
- The synthesis begins with a Mannich reaction between 2-acetylpyridine, formaldehyde, and pyrrolidine to form a Mannich base.
- This intermediate is then reacted with 4-methylphenylmagnesium bromide (a Grignard reagent) to introduce the tolyl group.
- The resulting tertiary alcohol is subjected to acid-catalyzed dehydration to form the alkene, establishing the specific geometry of the triprolidine structure.
- Finally, the product is treated with hydrochloric acid to yield the stable Triprolidine hydrochloride salt.
Antimetabolites
Answer
Antimetabolites are a class of antineoplastic agents that act as structural analogs of naturally occurring metabolites (such as purines, pyrimidines, or folic acid) required for DNA and RNA synthesis. By mimicking these substrates, they interfere with cellular metabolism, leading to the inhibition of enzymes like dihydrofolate reductase or DNA polymerase, ultimately causing cell cycle arrest and apoptosis.
Key categories include:
- Folic acid antagonists: Methotrexate inhibits dihydrofolate reductase, blocking the conversion of dihydrofolate to tetrahydrofolate, which is essential for thymidylate synthesis.
- Pyrimidine analogs: 5-Fluorouracil (5-FU) is converted to 5-FdUMP, which forms a stable ternary complex with thymidylate synthase, preventing the synthesis of thymidine.
- Purine analogs: 6-Mercaptopurine and 6-Thioguanine inhibit the de novo synthesis of purine nucleotides by acting as false substrates for hypoxanthine-guanine phosphoribosyltransferase (HGPRT).
Plant derived anticancer agents
Answer
Sign in to view the complete answer paper.
Classify diuretics? Describe the mechanism of action, therapeutic uses, and synthesis of Chlorthiazide.
Answer
Sign in to view the complete answer paper.
Classify anti-anginal agents? Describe the mechanism of action and synthesis of Isosorbide dinitrite.
Answer
Sign in to view the complete answer paper.
Describe the synthesis of Disopyramide phosphate and warfarin.
Answer
Sign in to view the complete answer paper.
Classify antihyperlipidemic agents? Describe their mechanism of actions and therapeutic uses.
Answer
Sign in to view the complete answer paper.
Classify oral contraceptives? Describe their mechanism of actions and adverse effects.
Answer
Sign in to view the complete answer paper.
Classify local anesthetics and describe their structure activity relationships.
Answer
Sign in to view the complete answer paper.