Synthesis and antibacterial activity of a novel series of potent DNA gyrase inhibitors. Pyrazole derivatives.

We have previously found that a pyrazole derivative 1 possesses antibacterial activity and inhibitory activity against DNA gyrase and topoisomerase IV. Here, we synthesized new pyrazole derivatives and found that 5-[(E)-2-(5-chloroindol-3-yl)vinyl]pyrazole 16 possesses potent antibacterial activity and selective inhibitory activity against bacterial topoisomerases. Many of the synthesized pyrazole derivatives were potent against clinically isolated quinolone- or coumarin-resistant Gram-positive strains and had minimal inhibitory concentration values against these strains equivalent to those against susceptible strains.