About Medicinal Chemistry III
Subject Code
BP601T
Semester
Semester 6
Credits
4 Credits
Medicinal Chemistry III (BP601T) is a comprehensive study of anti-infective agents and drug design principles. It covers the chemistry, SAR, and mechanism of action of all major classes of antibiotics (β-Lactams, Aminoglycosides, Tetracyclines, Macrolides), antimalarials, anti-tubercular agents, antivirals, antifungals, antiprotozoals, anthelmintics, and sulfonamides. The subject concludes with an introduction to rational drug design — QSAR, pharmacophore modeling, and combinatorial chemistry.
Key Learning Objectives
- Antibiotics: Understand the SAR, mechanism, resistance, and clinical significance of β-Lactams, Aminoglycosides, Tetracyclines, and Macrolides.
- Anti-infectives: Study the medicinal chemistry of antimalarials, anti-TB drugs, antivirals, antifungals, and sulfonamides.
- SAR Analysis: Correlate chemical structure modifications with changes in biological activity for each drug class.
- Drug Design: Apply QSAR principles (Hansch analysis, Hammett σ, Taft Es) to predict drug activity from physicochemical parameters.
- Combinatorial Chemistry: Understand the concepts of solid-phase and solution-phase synthesis for rapid drug discovery.
Syllabus & Topics Covered
Unit 1: Antibiotics – β-Lactams, Aminoglycosides & Tetracyclines
- Historical background, Nomenclature, Stereochemistry, Structure-activity relationship, Chemical degradation, classification of antibiotics.
- β-Lactam antibiotics: Penicillin, Cephalosporins, β-Lactamase inhibitors, Monobactams.
- Aminoglycosides: Streptomycin, Neomycin, Kanamycin.
- Tetracyclines: Tetracycline, Oxytetracycline, Minocycline, Doxycycline.
Unit 2: Antibiotics (contd.), Prodrugs & Antimalarials
- Macrolide antibiotics: Erythromycin, Clarithromycin, Azithromycin.
- Miscellaneous antibiotics: Chloramphenicol, Clindamycin.
- Prodrugs: Basic concepts and applications of prodrug design.
- Antimalarials – Etiology of malaria.
- Quinolines: SAR, Quinine sulphate, Chloroquine, Amodiaquine, Primaquine phosphate, Pamaquine, Quinacrine hydrochloride, Mefloquine.
- Biguanides and dihydrotriazines: Cycloguanil pamoate, Proguanil.
- Miscellaneous antimalarials: Pyrimethamine, Artesunate, Artemether, Atovaquone.
Unit 3: Anti-TB, Quinolones & Antivirals
- Synthetic anti-tubercular agents: Isoniazid, Ethionamide, Ethambutol, Pyrazinamide, Para-aminosalicylic acid.
- Anti-tubercular antibiotics: Rifampicin, Rifabutin, Cycloserine, Streptomycin, Capreomycin sulphate.
- Urinary tract anti-infective agents – Quinolones: SAR, Nalidixic Acid, Norfloxacin, Ciprofloxacin, Ofloxacin, Lomefloxacin, Sparfloxacin, Moxifloxacin.
- Miscellaneous UTI agents: Furazolidone, Nitrofurantoin, Methenamine.
- Antiviral agents: Amantadine, Rimantadine, Idoxuridine, Acyclovir, Ganciclovir, Zidovudine, Didanosine, Lamivudine, Ribavirin, Saquinavir, Indinavir, Ritonavir.
Unit 4: Antifungals, Antiprotozoals, Anthelmintics & Sulfonamides
- Antifungal antibiotics: Amphotericin-B, Nystatin, Natamycin, Griseofulvin.
- Synthetic antifungals: Clotrimazole, Miconazole, Ketoconazole, Itraconazole, Fluconazole, Naftifine, Tolnaftate.
- Antiprotozoal agents: Metronidazole, Tinidazole, Ornidazole, Diloxanide, Pentamidine isethionate, Eflornithine.
- Anthelmintics: Diethylcarbamazine, Mebendazole, Albendazole, Niclosamide, Praziquantel, Ivermectin.
- Sulfonamides: SAR, Sulfamethoxazole, Sulfadiazine, Sulfacetamide, Sulfasalazine.
- Folate reductase inhibitors: Trimethoprim, Cotrimoxazole. Sulfones: Dapsone.
Unit 5: Introduction to Drug Design & Combinatorial Chemistry
- Various approaches used in drug design.
- QSAR: Partition coefficient, Hammett’s electronic parameter, Taft’s steric parameter, and Hansch analysis.
- Pharmacophore modeling and docking techniques.
- Combinatorial Chemistry: Concept and applications, solid-phase and solution-phase synthesis.
How to Score High in Medicinal Chemistry III
- 1
Master SAR Tables: For each antibiotic class, draw the parent structure and annotate which positions affect activity, spectrum, and resistance.
- 2
Draw Mechanisms: Understand how β-Lactams inhibit PBPs, how Quinolones inhibit DNA gyrase, and how NRTIs work as chain terminators.
- 3
Link with Pharmacology: Connect the medicinal chemistry you learn here with the pharmacology of these drugs (from Pharmacology 2 & 3).
- 4
QSAR Problems: Practice solving Hansch equation problems — they are guaranteed numerical questions in exams.
Why it Matters for Career
Medicinal Chemistry 3 is directly relevant to pharmaceutical R&D, drug design, and QSAR modeling careers. Understanding antibiotic SAR is essential for antimicrobial stewardship programs and for medicinal chemists designing next-generation anti-infectives to combat drug resistance.
Exam Weightage
Units 1-2 (Antibiotics + Antimalarials) and Unit 4 (Antifungals + Sulfonamides) carry the highest marks. SAR questions are guaranteed. Unit 5 (QSAR/Hansch analysis) often has a numerical problem. Draw structures neatly and annotate SAR points.
Frequently Asked Questions (FAQs)
Is Medicinal Chemistry 3 harder than Medicinal Chemistry 2?
MC-3 focuses on anti-infective agents with heavy emphasis on antibiotic structures and SAR. If you find organic structures difficult, it can be challenging. However, many topics (Sulfonamides, Quinolones, Antimalarials) have systematic SAR that is easy to learn once you understand the parent scaffold.
Do I need to draw drug structures in the exam?
Yes. Medicinal Chemistry exams require drawing complete chemical structures with correct stereochemistry. Practice drawing Penicillin G, Chloroquine, Isoniazid, Metronidazole, Fluconazole, and Sulfamethoxazole until you can do it from memory.
What is QSAR and why is it important?
QSAR (Quantitative Structure-Activity Relationship) is a mathematical approach to correlating chemical structure with biological activity. Using parameters like log P (lipophilicity), σ (electronic), and Es (steric), you can predict a drug’s activity before synthesizing it — saving years of trial-and-error. The Hansch equation is the most commonly tested QSAR topic.