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 α-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 μg/ml. Among synthesized compounds, compound 6h (MIC = 1.25 μg/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 (IC 50 ) against in a mammalian Vero cell line using MTT assay. The results reveal that these compounds exhibit anti-tubercular activity at non-cytotoxic concentrations. Graphical Abstract Synthesis, spectral studies and anti-tubercular activity of a novel series of eighteen new 2-substituted-5,6-diarylsubstituted imidazo-(2,1-b)-1,3,4-thiadiazole derivatives are described.