1H-1,2,3-triazole embedded Isatin-Benzaldehyde-bis(heteronuclearhydrazones): design, synthesis, antimycobacterial, and cytotoxic evaluation.

Rapid growth of global drug-resistant tuberculosis and urgent requirement for short treatment regimens is stimulating the need for discovery of new TB drugs. In this work, we report the design, synthesis and in vitro antimycobacterial evaluation of a library of isatin-derived bis(heteronuclear hydrazones). Evaluation results revealed that the inclusion of isoniazid core into 1H-1,2,3-triazole tethered isatin-benzaldehydes improved the antimycobacterial activity on tuberculosis mc2 6230 strain and significantly reduced the cytotoxicity against Vero cells. However, the introduction of semicarbazones/thiosemicarbazones or pyrazine-2-carbohydrazide produced the opposite effects. The compounds with isoniazid and polar-donating groups at the C-5 position of isatin emerged as the most promising conjugates with MIC99  = 0.36 µg/ml. The most active compounds were non-cytotoxic to Vero cells (IC50 >100 µg/ml) with selectivity indices >277.