Antimycobacterial agents antibiotics

The cell walls of mycobacteria contain three structures peptidoglycan, an arabinogalactan polysaccharide and long chain hydroxy fatty acids (mycolic acids) which are all covalently linked. Additional non-covalently attached lipid components found in the wall include glycolipids, various phospholipids and waxes. The lipid-rich nature of the mycobacterial wall is responsible for the characteristic acid-fastness on staining and serves as a penetration barrier to many antibiotics. Isoniazid and ethambutol have long been known as specific antimycobacterial agents but their mechanisms of action have only recently become more clearly understood. 

Pharmacology Rifabutin, an antimycobacterial agent, is a semisynthetic ansamycin antibiotic derived from rifamycin S. It is not known whether rifabutin inhibits DNA-dependent RNA polymerase in Mycobacterium avium or in Mycobacterium... 

Selective reduction of m-dinitrobenzene (121) followed by, successively, diazotiza-tion, introduction of hydroxyl, reduction of the nitro group and carboxylation, yields the antimycobacterial agent p-aminosalicylic acid (122) (Scheme 25) used with the antibiotic streptomycin. A three-step synthesis starting with toluene yields the inexpensive drug thioacetazone (123). 

A few typical representatives of the second-line drugs used as antimycobacterial agents, namely Neomycin, Kanamycin, and Streptomycin have already been discussed under the chapter on Antibiotics . 

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