Gatifloxacin derivatives:: Synthesis, antimycobacterial activities, and inhibition of Mycobacterium tuberculosis DNA gyrase

Sixteen 7-substituted gatifloxacin derivatives were synthesized and evaluated for antimycobacterial activity in vitro and in vivo against Mycobacterium tuberculosis H37Rv (MTB) and multi-drug resistant M. tuberculosis (MDR-TB), and also tested for the ability to inhibit the supercoiling activity of DNA gyrase from M. tuberculosis. Among the synthesized compounds, 1-cyclopropyl-6-fluoro-8-methoxy-7-[[[N-4-[I'-(5-isatinyl-beta-semicarbazo)]methyl]3-methyl]N-1-piperazinyl]-4-oxo-1,4-dihydro-3-quinoline carboxylic acid (3d) was found to be the most active compound in vitro with an MIC of 0.0125 mu g/mL against MTB and MTR-TB. In the in vivo animal model 3d decreased the bacterial load in lung and spleen tissues with 3.62- and 3.76-log 10 protections, respectively. Compound 3d was also found to be equally active as gatifloxacin in the inhibition of the supercoiling activity of wild-type M. tuberculosis DNA gyrase with an IC50 of 3.0 mu g/mL. The results demonstrate the potential and importance of developing new quinolone derivatives against mycobacterial infections. (c) 2006 Elsevier Ltd. All rights reserved.