RESUMO
Fluoroquinolones are an important group of antimicrobial agents that are used widely in the treatment of various infectious diseases. The purpose of the present study was to synthesize new N-piperazinyl quinolone derivatives with 5-chloro-2-theinyl group having possible antimicrobial activity. Reaction of ciprofloxacin [1], norfloxacin [2] and enoxacin [3] with alpha-bromoketone 10 or alpha-bromooxime derivatives 11a-c in DMF, in the presence of NaHCO[3] at room temperature, afforded corresponding ketones 4a-c or oxime derivatives 5-7[a-c], respectively. The synthesized compounds were tested against a series of Gram-positive and Gram-negative bacteria. The results of MIC tests against both Gram-positive and Gram-negative bacteria revealed that ciprofloxacin derivatives [compounds 4a, 5a, 6a and 7a] were more active than norfloxacin and enoxacin analogues. Compound 5a, containing N-[2-[5-chlorothiophen-2-yl]-2-hydroxyiminoethyl] residue provided a high in vitro antibacterial activity against Gram-positive bacteria, with MIC of 0.06, 0.125, 0.5 and 0.125 micro g/mL against S. aureus, S. epidermidis, E. feacalis and B. subtilis, respectively. Its activity was found to be 4 to 8 times better than reference drug [ciprofloxacin] against all Gram-positive bacteria with the exception of E. feacalis