Synthesis, spectral studies and biological evaluation of a novel series of 2-substituted-5,6-diarylsubstituted imidazo(2,1-b)-1,3,4-thiadiazole derivatives as possible anti-tubercular agents

A novel series of 18 analogs of 2-substituted-5,6-diarylsubstituted imidazo(2,1-b)-1,3,4-thiadiazole 6a-r have been synthesized by the reaction of 2-amino-5-substituted-1,3,4-thiadiazoles 5a-d and an appropriately substituted alpha-bromo-1,2-(p-substituted)diaryl-1-ethanones 4a-e. Structures of these compounds were established by physiochemical, elemental analysis and spectral data. All the title compounds were tested for their in-vitro anti-tubercular activity against Mycobacterium tuberculosis H(37)Rv using Alamar Blue susceptibility test and the activity expressed as the minimum inhibitory concentration (MIC) in mu g/ml. Among synthesized compounds, compound 6h (MIC = 1.25 mu g/ml) exhibited excellent anti-tubercular activity with respect to other synthesized compounds and reference drugs. Compounds 6c, 6f, and 6g have also displayed an encouraging anti-tubercular activity profile. Further, some title compounds were also assessed for their cytotoxic activity (IC50) against in a mammalian Vero cell line using MTT assay. The results reveal that these compounds exhibit anti-tubercular activity at non-cytotoxic concentrations.