Gatifloxacin‐1,2,3‐triazole‐isatin hybrids and their antimycobacterial activities

A series of gatifloxacin‐1,2,3‐triazole‐isatin hybrids 8a–l were designed, synthesized, and screened for their in vitro antimycobacterial activity as well as cytotoxicity toward Chinese Hamster Ovary (CHO) cells. The synthesized hybrids showed considerable activity against MTB H₃₇Rv and two MDR‐MTB strains with minimal inhibitory concentration (MIC) of 0.25–8 μg/ml, and the hybrid 8a (MIC_{MTB H37Rv}: 0.25 μg/ml and MIC_MDR‐MTB: 0.5 and 1 μg/ml) was found to be most active against the tested strains, which was not inferior to the parent gatifloxacin (MIC: 0.5, 0.25, and 0.5 μg/ml) against all three tested strains, and was ≥128‐fold more active than isoniazid (MIC: ≥64 μg/ml) and rifampicin (MIC: >128 μg/ml) against the two MDR‐MTB strains. Moreover, hybrid 8a (CC₅₀: 8.0 μg/ml) also displayed acceptable cytotoxicity toward CHO cells, and the selectivity index was 32. The structure–activity relationship and structure–cytotoxicity relationship were also enriched.