Ciprofloxacin–Isatin Hybrids and Their Antimycobacterial Activities

Abstract

A series of diethylene glycol tethered ciprofloxacin–isatin hybrids 5a–j were designed, synthesized, and evaluated for their in vitro antimycobacterial activity against both drug‐sensitive and multidrug‐resistant (MDR) Mycobacterium tuberculosis strains in this paper. The preliminary results revealed that all hybrids with greater lipophilicity than the parent ciprofloxacin displayed considerable activity against the tested strains with minimum inhibitory concentration (MIC) in a range of 1.56–64 μg/mL. In particular, hybrid 5f (MIC: 1.56 and 2 μg/mL) with low cytotoxicity in VERO cell line was comparable with the parent ciprofloxacin (MIC: 0.78 and 2 μg/mL) against M. tuberculosis H37Rv and MDR tuberculosis strains and ≥16‐fold more potent than isoniazid and rifampicin (MIC: >128 and 32 μg/mL, respectively) against MDR tuberculosis, suggesting that it may serve as a new and promising candidate for further study.