Here in, we report the design, synthesis, and antibacterial activity of series of bulky arenesulfonamido derivatives using ciprofloxacin and norfloxacin as scaffolds. All the synthesized compounds were investigated in vitro for their antibacterial activities against two Gram-positive and two Gram-negative organisms using dilution broth method. Among the tested compounds examined, compounds 3-7 showed significance difference from the standard drug ciprofloxacin. 2D-QSAR study provides details on the fine relationship linking structure and activity and offers clues for structural modifications that can improve the activity. Docking study of the compound 3b into the active site of the topoisomerase II DNA-gyrase enzymes revealed a similar binding mode to ciprofloxacin with additional classical and nonclassical hydrogen bonds.
Quinolones are one of the types of antibiotics with higher resistance rates in the last years. At molecular level, quinolones block type II topoisomerases producing double strand breaks (DSBs). These DSBs could play a double role, as inductors of the quinolone bactericidal effects but also as mediators of the resistance and tolerance mechanisms.
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A thin-layer chromatographic (TLC) assay for the determination of norfloxacin (1-ethyl-6-fluoro-1,4-dihydro-4-oxo-7- (piperazinyl)-3-quinolinecarboxylic acid), a new antibacterial agent, in human plasma and urine is described. Norfloxacin was extracted from plasma samples using commercial cartridges, urine samples were simply diluted with methanol. Plasma extracts or urine samples were applied to TLC plates (silica gel). Chromatography was performed with a mobile phase consisting of methanol, ethanol and water, the atmosphere in the tank being saturated with ammonia. The fluorescence intensity of norfloxacin was enhanced by dipping the plate into a paraffin/citric acid mixture. Peaks were quantified by fluorimetric measurement (excitation 313 nm/emission 390 nm, cut-off filter). The method showed acceptable precision and linearity in the range of 0.01 to 4 micrograms/ml for plasma and 1 to 100 micrograms/ml for urine. The assay was shown to be applicable to human plasma and urine samples.
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Quinobenzoxazine A-62176, developed from the antibacterial fluoroquinolones, is active in vitro and in vivo against murine and human tumors. It has been previously claimed that A-62176 is a catalytic inhibitor of mammalian topoisomerase II that does not stabilize the cleaved complex. However, at low drug concentrations and pH 6-7, we have found that A-62176 can enhance the formation of the cleaved complex at certain sites. Using a photocleavage assay, mismatched sequences, and competition experiments between psorospermin and A-62176, we pinpointed the drug binding site on the DNA base pairs between positions +1 and +2 relative to the cleaved phosphodiester bonds. A 2:2 quinobenzoxazine-Mg2+ self-assembly model was previously proposed, in which one drug molecule intercalates into the DNA helix and the second drug molecule is externally bound, held to the first molecule and DNA by two Mg2+ bridges. The results of competition experiments between psorospermin and A-62176, as well as between psorospermin and A-62176 and norfloxacin, are consistent with this model and provide the first evidence that this 2:2 quinobenzoxazine-Mg2+ complex is assembled in the presence of topoisomerase II. These results also have parallel implications for the mode of binding of the quinolone antibiotics to the bacterial gyrase-DNA complex.
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Four fluoroquinolone antibiotics (norfloxacin, ciprofloxacin, lomefloxacin, and enrofloxacin) in tap water in Guangzhou and Macao were analyzed using high performance liquid chromatography fluorescence detection. The results showed that all target antibiotics were detected in high rate both in Guangzhou (77.5%) and Macao (100%), ranging from 1.0 to 679.7 ng/L (SD
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We performed a 5-year retrospective study to evaluate the effect of long-term administration of norfloxacin on the epidemiology of severe hospital-acquired infections in patients with advanced cirrhosis. Sixty-seven episodes of spontaneous bacterial peritonitis and 60 episodes of bacteremia occurred in, respectively, 46 patients (group 1a) and 52 patients (group 1b) who did not receive norfloxacin, while 23 and 17 episodes occurred in 21 patients (group 2a) and 17 patients (group 2b) during or within 10 days after long-term administration of norfloxacin. Enterobacteriaceae were more prevalent in groups 1a and 1b than in the other two groups (P < .001 and P < .01, respectively); conversely, staphylococci were more prevalent in groups 2a and 2b (P < .001 and P < .05, respectively). The rate of staphylococcal resistance to methicillin was 53.6% in groups 1a and 1b and 77.3% in groups 2a and 2b. We conclude that long-term norfloxacin administration to cirrhotic patients reduces the risk of gram-negative infections but increases the risk of severe hospital-acquired staphylococcal infections and of high-level resistance to antibiotics.
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Recent observations have suggested that classic antibiotics kill bacteria by stimulating the formation of reactive oxygen species (ROS). If true, this notion might guide new strategies to improve antibiotic efficacy. In this study, the model was directly tested. Contrary to the hypothesis, antibiotic treatment did not accelerate the formation of hydrogen peroxide in Escherichia coli and did not elevate intracellular free iron, an essential reactant for the production of lethal damage. Lethality persisted in the absence of oxygen, and DNA repair mutants were not hypersensitive, undermining the idea that toxicity arose from oxidative DNA lesions. We conclude that these antibiotic exposures did not produce ROS and that lethality more likely resulted from the direct inhibition of cell-wall assembly, protein synthesis, and DNA replication.
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Two octanordammaranes, mansumbinone (1) and 3,4-seco-mansumbinoic acid (2), and two sesquiterpenes, beta-elemene (3) and T-cadinol (4) have been isolated from the oleo-resin of Commiphora molmol (Engl.). The structures of these compounds were established unambiguously by a series of 1D and 2D-NMR analyses. We have also unambiguously assigned all (1)H and (13)C NMR resonances for 2 and revised its (13)C data. The crude extract of the oleo-resin of C. molmol displayed potentiation of ciprofloxacin and tetracycline against S. aureus, several Salmonella enterica serovar Typhimurium strains and two K. pneumoniae strains. The antibacterial activity of terpenes 1-4 was determined against a number of Staphylococcus aureus strains: SA1199B, ATCC25923, XU212, RN4220 and EMRSA15 and minimum inhibitory concentration (MIC) values were found to be in the range of 4-256 microg/ml. The highest activity was observed by the seco-A-ring octanordammarane 2 with an MIC of 4 microg/ml against SA1199B, a multidrug-resistant strain which over-expresses the NorA efflux transporter, the major characterized antibiotic pump in this species. This activity compared favorably to the antibiotic norfloxacin with an MIC of 32 microg/ml. Compound 2 also displayed weak potentiation of ciprofloxacin and tetracycline activity against strains of Salmonella enterica serovar Typhimurium SL1344 and L10.
Infection after flexible cystoscopy is rare and not associated with significant morbidity. A much larger study would be required to determine whether antibiotic prophylaxis significantly reduces the rate of postprocedure UTI.
The direct viable count (DVC) is a procedure for enumerating viable-nonculturable cells. It should be noted, however, that bacteria demonstrating the viable but nonculturable phase have to date included only Gram-negative species, mainly because the DVC procedure does not lend itself to the analysis of Gram-positive bacteria since the DVC procedure is dependent on the bacterium being sensitive to nalidixic acid. The authors report here concerning studies on an analogous procedure for the direct enumeration of viable-nonculturable Gram-positive bacteria. To facilitate a differential DVC for Gram-positive bacteria, ciprofloxacin, enoxacin, norfloxacin or isopropyl cinodine were substituted for nalidixic acid. These antibiotics were chosen because, like nalidixic acid, they are DNA gyrase inhibitors. The concentrations used for each antibiotic were 1000 micrograms ml-1, 100 micrograms ml-1. Pure cultures of Staphylococcus aureus, Enterococcus faecalis, Streptococcus agalactiae, Listeria monocytogenes and Bacillus subtilis were obtained from the culture collection at the University of Wyoming and a faecal streptococcus was isolated from the Laramie wastewater treatment plant. An antibiotic and optimal concentration thereof was found which gave enlarged cells for all the organisms except the faecal streptococcus isolated from the wastewater plant for which no enlarged cells were ever seen. The antibiotic and concentration thereof which gave the optimal percent enlarged cells in the DVC procedure varied between organisms.
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A simple and rapid ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) coupled with liquid chromatography-ultraviolet detection (LC-UV) was developed for the determination of four fluoroquinolones (ofloxacin, norfloxacin, enrofloxacin, and lomefloxacin) in pharmaceutical wastewater samples. Various parameters affecting the extraction efficiency including type and volume of extraction and dispersive solvents, sample pH, and extraction time were investigated. Good linear relationships were obtained for all analytes in a range of 0.01-2.0 μg/ml with LODs ranged from 0.14 to 0.81 μg/l. Average recoveries at three spiking levels were over the range of 82.7-110.9% with RSD less than 5.2% (n=3). Under the optimized conditions the enrichment factors for the four fluoroquinolones were ranged from 32 to 134 folds. The presented method was applied for the determination of four fluoroquinolones in pharmaceutical wastewater samples.
Nalidixic acid and three fluoroquinolones were tested on 389 strains belonging to 13 bacterial species, all isolated in Algeria. Ofloxacin, norfloxacin and pefloxacin have the same activities on E. coli, Acinetobacter and S. aureus. Norfloxacin has the best activity on Proteus, Enterobacter, Shigella and Klebsiella. Norfloxacin and ofloxacin have the same activities on S. typhi, Salmonella and choleric Vibrio. Norfloxacin has the same activity than pefloxacin on P. aeruginosa. It is necessary to prescribe a quinolone in the right way and to consider the pharmacokinetic properties.
As part of a monitoring programme the in vitro susceptibility of 1604 isolates of N gonorrhoeae was determined by agar dilution. Auxo- and serotyping was performed on 1350 and 1313 isolates respectively.
Ciprofloxacin (C), pefloxacin (P) and norfloxacin (N) had a marked effect on Yersinia pseudotuberculosis strains isolated from the infected humans and animals. The activity of C (MIC 0.0312-0.125 microgram/ml) was higher than that of P and N (MIC 0.0625-2.0 micrograms/ml). The isolates were resistant to azithromycin (MIC 3.1-100 micrograms/ml). The susceptibility of the strains did not depend on the source of their isolation. The polyresistant strains carrying the R plasmids preserved the susceptibility to the fluoroquinolones.
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Norfloxacin exerts immunomodulatory effects in cirrhosis beyond its bactericidal activity. We aimed at identifying the role of regulatory T (Treg) cells in the norfloxacin mechanism that compensates the inflammatory environment in cirrhosis.