Synthesis and in vitro antimycobacterial activity of 8-OCH(3) ciprofloxacin methylene and ethylene isatin derivatives

A series of novel 8-OCH(3) ciprofloxacin methylene and ethylene isatin derivatives with remarkable improvement in lipophilicity were synthesized in this study. These derivatives were evaluated for their in vitro activity against some mycobacteria. All of the synthesized compounds were less active than the parent 8-OCH(3) ciprofloxacin against Mycobacteriumsmegmatis CMCC 93202, but most of the methylene isatin derivatives were more active than 8-OCH(3) ciprofloxacin, ciprofloxacin, isoniazid and rifampin against MTB H37Rv ATCC 27294. It was noted that compound 3b (MIC: 0.074 μM) was 2-13 fold more potent than the reference compounds against MTB H37Rv ATCC 27294, and compounds 3f and 3i-k (MIC: 6.72-7.05 μM) were around 1.6 fold more potent than the parent 8-OCH(3) ciprofloxacin, 3.5 fold more potent than ciprofloxacin against MDR-MTB 09710.