title: Synthesis of 6-fluoro-1,4-dihydro-4-oxo-quinoline-3-carboxylic acid derivatives as potential antimicrobial agents.
abstract: In the present study, a series of 1-ethyl/benzyl-6-fluoro-7-(substituted piperazin-1-yl)1,4-dihydro-4-oxo-quinoline-3-carboxylic acid were synthesized and characterized by IR, 1H-NMR, mass spectral and elemental analysis. The in vitro antibacterial and antifungal activities of the compounds were evaluated by paper disc diffusion method. The minimum inhibitory concentrations (MIC) of the compounds were also determined by agar streak dilution method. The in vivo antibacterial activity of the compounds against Escherichia coli was also evaluated by mouse protection test. All the compounds exhibited significant antibacterial and weak antifungal activities. The in vivo antibacterial activity (ED50) against E. coli was 50-160 mg kg(-1) in the order of 7<9<8<10. 1-ethyl-6-fluoro-7-(2,5-dioxo-piperazin-1-yl)1,4-dihydro-4-oxo-quinoline-3-carboxylic acid (7) was found to exhibit the most potent in vitro antimicrobial activity with MIC of 4.1, 3.1, 3.1, 2.4, 1, 1, 25 and >100 microg mL(-1) against Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus luteus, Bacillus cereus, E. coli, Klebsiella pneumoniae, Candida albicans and Aspergillus niger.
authors.affiliation: Department of Pharmaceutical Chemistry and Pharmacology, C L Baid Metha College of Pharmacy, Jyothi Nagar, Thorapakkam, Chennai 600096, Tamilnadu, India. clbmcpl@md4.vsnl.net.in
authors.forename: Natesh
authors.initials: N
authors.lastname: Rameshkumar
authors.forename: Mohan
authors.initials: M
authors.lastname: Ashokkumar
authors.forename: Ekambaram Harihara
authors.initials: EH
authors.lastname: Subramanian
authors.forename: Raju
authors.initials: R
authors.lastname: Ilavarasan
authors.forename: Seshaiah Krishnan
authors.initials: SK
authors.lastname: Sridhar
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000138:chemical synthesis* / Q000494:pharmacology; D000890:Anti-Infective Agents / Q000138:chemical synthesis / Q000494:pharmacology; D000935:Antifungal Agents / Q000138:chemical synthesis* / Q000494:pharmacology; D002264:Carboxylic Acids / Q000138:chemical synthesis* / Q000494:pharmacology; D008297:Male; D051379:Mice; D008826:Microbial Sensitivity Tests; D015363:Quinolones / Q000138:chemical synthesis* / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D000935:Antifungal Agents; D002264:Carboxylic Acids; D015363:Quinolones