Antimycobacterial activity of substituted isosteres of pyridine- and pyrazinecarboxylic acids

Pyrazines and pyridines substituted with alkylated tetrazoles, esterified vinylogous carboxylic acids, and ketosulfides were synthesized as precursors of antimycobacterial agents which, after penetration of the mycobacterial cell wall, could be biotransformed by esterases or peroxidase-catalases. The expected products are tetrazoles, a vinylogous carboxylic acid, and CH-acidic ketosulfoxides, isosteres of pyrazinoic and nicotinic acids, which should inhibit mycobacterial growth when released inside the bacterial cell. The growth inhibitory activity of the synthesized compounds against the H37Rv strain of Mycobacterium tuberculosis was determined to assess the viability of this concept. It was shown that all of the compounds designed as lipophilic precursors were more active than the unmodified polar isosteres of pyrazinoic and nicotinic acids.