Synthesis and in vitro antibacterial activity of some N-(5-aryl-1,3,4-thiadiazole-2-yl)piperazinyl quinolone derivatives.

A series of N-[5-(1-methyl-5-nitro-2-imidazolyl)-1,3,4-thiadiazole-2-yl] and N-[5-(nitrophenyl)-1,3,4-thiadiazole-2-yl] piperazinyl quinolone derivatives (5a-c and 5d-l) were synthesized and evaluated for in vitro antibacterial activity against some Gram-positive and Gram-negative bacteria. The antibacterial data revealed that all nitroimidazole derivatives (5a-c) showed interesting activity against tested Gram-positive bacteria (minimum inhibitory concentration, MIC=0.008-0.03 microg/ml) while they did not show good activity against Gram-negative organisms. Despite the significant activity of nitroimidazole series, all nitrophenyl analogues (5d-l) were inactive against both Gram-positive and Gram-negative bacteria. Among all of the tested compounds, 5a (ciprofloxacin derivative in nitroimidazole series) exhibited excellent activity against Staphylococcus aureus and Staphylococcus epidermidis (MIC=0.008 microg/ml).