Macrolides | Prodrugs | Antimalarials | Unit 2 Medicinal Chemistry 6th Semester

The lecture comprehensively covers Unit 2 of 6th semester Medicinal Chemistry, divided into four main sections. First, it discusses Macrolides, which are bacteriostatic antibiotics derived from Streptomyces species. The speaker explains that macrolides get their name from their large lactone ring structure (14-16 carbons) with attached sugar groups like desosamine and cladinose. The mechanism involves binding to the 50s ribosomal unit and blocking translocation of tRNA from A-site to P-site, ultimately halting protein synthesis. Key drugs include erythromycin, clarithromycin, and azithromycin. The second section covers miscellaneous antibiotics, particularly chloramphenicol (a star drug) which also binds to 50s ribosomal units but works by inhibiting peptide bond formation rather than tRNA translocation. A detailed synthesis of chloramphenicol is provided starting from para-nitro acetophenone. The third major section focuses on Prodrugs - inactive or less active drugs that require biotransformation to become pharmacologically active. These are designed to improve solubility, stability, absorption, reduce toxicity, or provide targeted delivery. Prodrugs are classified as carrier-linked (with removable carriers) or bioprecursors (involving structural changes). The final section covers Antimalarials, explaining the malaria lifecycle involving Plasmodium parasites transmitted by female Anopheles mosquitoes. The lifecycle alternates between human (asexual) and mosquito (sexual) stages. Antimalarial drugs are classified into quinolines (including 4-aminoquinolines and 8-aminoquinolines), biguanides, dihydrotriazines, and miscellaneous drugs, each with specific mechanisms targeting different stages of the parasite lifecycle.