Antituberculosis agents VIII. Synthesis and in vitro antimycobacterial activity of alkyl alpha-[5-(5-nitro-2-thienyl)-1,3,4-thiadiazole-2-ylthio]acetates.

A series of alkyl alpha-[5-(5-nitro-2-thienyl)-1,3,4-thiadiazole-2-ylthio]acetic acid esters 6a-e were synthesized and evaluated for in vitro antituberculosis activity against Mycobacterium tuberculosis strain H(37)Rv using the BACTEC 460 radiometric system and BACTEC 12B medium. The antituberculosis data indicated that methyl, propyl, buthyl and benzyl esters showed a significant in vitro antimycobacterium tuberculosis activity (MIC=0.39-0.78 microg/ml) and the ethyl analogue did not show a good activity (MIC>6.25 microg/ml, %inhibition=58). The most active compound of the series was n-propyl alpha-[5-(5-nitro-2-thienyl)-1,3,4-thiadiazole-2-ylthio]acetate (6c) with MIC value of 0.39 microg/ml.