Synthesis and In-Vitro Antimycobacterial Activity of Fluoroquinolone Derivatives Containing a Coumarin Moiety

A series of gatifloxacin, ciprofloxacin, and 8-OCH3 ciprofloxacin coumarin derivatives with remarkable improvement in lipophilicity as compared to the parent fluoroquinolones was designed, synthesized, and characterized by 1H-NMR, MS, and HRMS. These derivatives were evaluated for their in-vitro activity against Mycobacterium smegmatis CMCC 93202 and MTB H37Rv ATCC 27294. All of the synthesized compounds were less active than the parent compounds against M. smegmatis CMCC 93202, but the activity of compound 6 was found to be 28-fold more potent than ciprofloxacin, 8-OCH3 ciprofloxacin, moxifloxacin, and rifampin, and comparable to gatifloxacin against MTB H37Rv ATCC 27294. These results indicated that the lipophilicity of the tested compounds is not the sole parameter affecting antimycobacterial activity.