Medicinal Chemistry

Chemical Structure / Formula of Trimethoprim Formula: C₁₄H₁₈N₄O₃ Structure: Pyrimidine derivative. Mechanism of Action Inhibits dihydrofolate reductase (DHFR), blocking bacterial DNA synthesis. Uses UTIs, respiratory tract infections (combined with sulfamethoxazole = Cotrimoxazole). Side Effects Megaloblastic anemia, hyperkalemia, GI upset. Synthesis of Trimethoprim Structure-Activity Relationship (SAR) of Trimethoprim Structural Feature SAR Insight 2,4-diaminopyrimidine ring Essential for … Read more

Chemical Structure / Formula of Sulfasalazine Formula: C₁₈H₁₄N₄O₅S Structure: A conjugate of sulphapyridine and 5-aminosalicylic acid (5-ASA) linked by an azo bond. Mechanism of Action In colon, azo bond is cleaved by gut bacteria to release 5-ASA (anti-inflammatory) and sulphapyridine (antibacterial). Anti-inflammatory effects beneficial in IBD; antibacterial properties aid in treating infections. Uses of Sulfasalazine … Read more

Chemical Structure / Formula of Mefenide Acetate Formula: C₉H₁₁N₃O₂S Structure: Sulfonamide derivative with a modified aromatic ring. Mechanism of Action Inhibits bacterial folate metabolism, similar to sulfonamides. Also penetrates eschar and has topical bacteriostatic Uses of Mefenide Acetate Topical agent for preventing infections in burn wounds. Active against Pseudomonas aeruginosa and other burn-related pathogens. Side … Read more

Chemical Structure / Formula of Sulphadiazine Formula: C₁₀H₁₀N₄O₂S Structure: Sulfonamide group with a diazine ring. Mechanism of Action Inhibits dihydropteroate synthase, interfering with folate synthesis. Bacteriostatic Uses of Sulphadiazine Used with pyrimethamine for toxoplasmosis. Treats malaria, meningitis, and urinary tract infections. Broad-spectrum activity against Gram-positive and Gram-negative bacteria. Side Effects Nausea, vomiting, hypersensitivity reactions. Crystalluria, … Read more

Chemical Structure / Formula of Sulfamethoxazole Formula: C₁₀H₁₁N₃O₃S Structure: Isoxazole-containing sulfonamide. Mechanism of Action Inhibits dihydropteroate synthase, blocking folic acid synthesis. Uses UTIs, respiratory tract infections (combined with trimethoprim = Cotrimoxazole). Side Effects Hypersensitivity reactions, crystalluria, nephrotoxicity. Synthesis of Sulfamethoxazole Structure-Activity Relationship (SAR) Structural Feature SAR Insight 5-methylisoxazole ring Enhances absorption and distribution. p-Aminobenzenesulfonamide core … Read more

Chemical Structure / Formula of Sulphapyridine Formula: C11H11N3O2S Structure: Sulfonamide group attached to a pyridine ring. Mechanism of Action Inhibits dihydropteroate synthase, blocking folic acid synthesis in bacteria. Bacteriostatic Uses of Sulphapyridine Used in the past for bacterial infections (e.g., pneumonia, UTIs). Largely replaced by newer sulfonamides due to side effects. Component of sulfasalazine (metabolized … Read more

Chemical Structure / Formula of Sulfacetamide Formula: C8H10N2O3S Structure: Acetamide-containing sulfonamide. Mechanism of Action Inhibits folic acid synthesis by competing with PABA. Uses Ophthalmic infections (bacterial conjunctivitis, corneal ulcers). Side Effects Local irritation, allergic reactions. Structure-Activity Relationship (SAR) Structural Feature SAR Insight Acetamide group Improves water solubility (used in ophthalmic preparations). Para-amino benzene sulfonamide core … Read more

Chemical Structure / Formula of Sulfamethizine Formula: C₁₂H₁₄N₄O₂S Structure: Thiazole-containing sulfonamide. Mechanism of Action Inhibits folic acid synthesis, preventing bacterial DNA replication. Uses of Sulfamethizine Respiratory and urinary tract infections. Side Effects Hypersensitivity reactions, nephrotoxicity, anemia.

Chemical Structure / Formula of Sulfapyridine Formula: C₁₁H₁₁N₃O₂S Structure: Pyridine-containing sulfonamide. Mechanism of Action Inhibits dihydropteroate synthase, blocking folate metabolism. Uses of Sulfapyridine Used in combination (as sulfasalazine) for inflammatory bowel diseases (IBD, ulcerative colitis, Crohn’s disease). Side Effects Hypersensitivity, GI upset, hemolysis in G6PD-deficient patients.

Chemical Structure / Formula of Sulfisoxazole Formula: C11H13N3O3S Structure: Isoxazole-containing sulfonamide. Mechanism of Action Inhibits folic acid synthesis by competing with para-aminobenzoic acid (PABA) for dihydropteroate synthase. Uses of Sulfisoxazole UTIs, otitis media (often in combination with erythromycin). Side Effects GI upset, allergic reactions, crystalluria.