• Bulletin of the Korean Chemical Society
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• v.24 no.5
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• pp.579-582
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• 2003

Norfloxacin, that inhibits the action of topoisomerase Ⅱ, binds to wide variety of DNA. The binding mode of this drug to double- and super-coiled DNA (ds- and scDNA) is compared in this study by various spectroscopic methods, including absorption, fluorescence, and circular dichroism(CD) spectroscopy. Hypochromism in the absorption band, negative and positive induced CD bands (respectively in 240-260 nm and 270-300 nm region) are apparent for the norfloxacin that bound to both the dsDNA and scDNA. A decrease in fluorescence is also noticed in the presence of both DNAs. Since the spectroscopic characteristics are the same for both complexes, it is imperative that the binding mode of the norfloxacin is similar in ds- and scDNA. In the presence of $Mg^{2+}$, which is a cofactor in the topoisomerase Ⅱ action, the fluorescence intensity of the scDNA-norfloxacin complex increased and the resulting fluorescence intensity and shape was identical to that in the absence of scDNA. Therefore, the addition of an excess amount of $Mg^{2+}$ may result in the extrusion of norfloxacin from scDNA.

• YAKHAK HOEJI
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• v.44 no.5
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• pp.406-410
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• 2000

The present method is to describe a potentiometric norfloxacin electrode system characterized by a membrane, based on the use of norfloxacin (NF) complex with ion-association reagents. These complexes were dissolved in DMSO, DMF acetonitrile or acetone and dispersed in plasticized poly(vinyl chloride) matrix. The picric acid complex electrode exhibited near-Nernstian response for NF in acetate buffer solution (pH 4.0) with a slope of 53.03 mV/decade. And linear response over the range of 10$^{-5}$ to 10$^{-3}$M solution of NE. The ingredients in tablet, capsule and biological important organic acids were not interfere.

• Journal of Microbiology
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• v.40 no.1
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• pp.63-69
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• 2002

A total of twenty-five norfloxacin resistant Escherichia coli were isolated from Joongrang-chun stream, a branch of the Han River in Seoul, Korea from May to July in 2000 and their norfloxacin resistance mechanism was characterized for target site mutation, permeability, and efflux pump. Fourteen iso- lates contained the same three mutations, Ser83→Leu and Asp87→Asn in GyrA and Ser90→ lle in ParC. Six isolates had Ser83→Leu and Asp87→Tyr in GyrA and Ser87→lle in ParC while one isolate had Ser83→Leu and Va1103→Ala in GyrA and Ser80→lle in ParC. Two isolates had mutation(s) in GyrA without any mutation in ParC. Two isolates had Ser80→Arg in ParC instead of the commonly found Ser80→lle. Every norfloxacin resistant isolate had an efflux system but the correlation between the efflux activity and MIC was not observed. The amount of OmpF for norfloxacin permeability decreased in resistant isolates compared to the susceptible strains. When amplified polymorphic DNA (RAPD) and pulse field gel electrophoresis (PFGE) were performed, these isolates showed no similarity to each other or clinical isolates.

• Bulletin of the Korean Chemical Society
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• v.25 no.3
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• pp.365-372
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• 2004

Two simple, rapid and sensitive spectrophotometric methods for the determination of three fluoroquinolones, namely levofloxacin, norfloxacin and ciprofloxacin have been performed either in pure form or in their tablets. In the first method, levofloxacin and norfloxacin are directly treated with bromocresol green (BCG) in dichloromethane while ciprofloxacin is allowed to react with the same dye in aqueous acidic buffer. Highly yellow colored complex species were formed instantaneously in case of levofloxacin and norfloxacin or after extraction into dichloromethane for ciprofloxacin. The formed complexes are quantified spectrophotometrically at their absorption maxima at 411 nm for levofloxacin and 412 nm for norfloxacin and ciprofloxacin. The second method involves the reaction of levofloxacin with ${\rho}$-chloranilic acid ( ${\rho}$-CA) and norfloxacin with tetracyanoethylene (TCNE) in acetonitrile to give complexes with maximum absorbance at 521 and 333 nm for the two drugs, respectively. Adopting the first procedure, calibration graphs were linear over the range 1- 20 ${\mu}g\;mL^{-1}$ with mean percentage recoveries of 100.41 ${\pm}$ 0.72, 99.99 ${\pm}$ 0.54 and 100.23 ${\pm}$ 0.91 for the theree drugs, respectively. For the second procedure, the concentration ranges were 15-250 ${\mu}g\;mL^{-1}$ for levofloxacin using ${\rho}$-CA and 0.8-16 ${\mu}g\;mL^{-1}$ for norfloxacin using TCNE with mean percentage recoveries of 99.88 ${\pm}$ 0.45 and 100.26 ${\pm}$ 0.68 for the two drugs, respectively. The proposed methods were successfully applied to determine these drugs in their tablet formulations and the results compared favorably to that of reference methods. The proposed methods are recommended for quality control and routine analysis.

• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3233-3238
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• 2011

The fluorescence of norfloxacin was quenched by various nucleotides. The ratio of the fluorescence intensities in the absence and presence of nucleotide was linearly dependent on nucleotide concentration, suggesting that quenching occurred through the formation of nonfluorescent norfloxacin-nucleotide complexes. The gradient of the linear relationship represented the equilibrium constant of complex formation; it decreased with increasing temperature. The slopes of van't Hoff plots constructed from the temperature-dependent equilibrium constants were positive in all cases, indicating that complex formation was energetically favorable - i.e., exothermic, with negative Gibb's free energy. The equilibrium constant increased when triphosphate was used instead of monophosphate. It also increased when the oxygen at the $C'_2$ position of the nucleotide was removed. Both enhancements were due to entropic effects: entropy decreased when complexes with AMP or GMP formed, while it increased when norfloxacin complexed with ATP, GTP, dAMP and dGMP.

• Polymer(Korea)
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• v.33 no.2
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• pp.137-143
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• 2009

We prepared norfloxacin (NFX)-incorporated polymeric micelle using poly ($\varepsilon$-caprolactone)/poly(ethylene glycol) (PCL/PEG, CE) diblock copolymers. Particle size was from 60 to 200 nm according to the PCL block length. Their critical association concentration (CAC) was decreased according to the increase of PCL block length. $^1H$-NMR study showed core-shell type micelle structures of CE diblock copolymers in the aqueous environment. Drug release from polymeric micelle was continued over 2 days. Duration of drug release was varied according to the PCL block length and drug contents. At antimicrobial activity test, polymeric micelle showed almost similar cytotoxicity compared to NFX itself.

• Korean Journal of Clinical Pharmacy
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• v.6 no.2
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• pp.14-18
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• 1996

This study was attempted to investigate the dissolution rate and the bioavailability after oral administration of commercially available norfloxacin tablets in rabbits. The dissolution test was conducted in artificial gastric juice using basket method with for norfloxacin preparations (A, B, C and D) which were chemically equivalent. The results were as follows ; The dissolution rate was increased in the order of four different brand A>D>B>C. Area under the plasma concentration curve and peak plasma concentration were increased in the order of brand A>D>B>C. Absorption rate constant and peak time were increased in the order of brand B>A>C>D, and there was a little difference in elimination rate constant and biological half-life. The correlation of the dissolution rate and relative bioavailability showed significant linear relationship. From the results of this experiment, the bioavailability of norfloxacin tablets in rabbits may be predicted from the results of dissolution rate studies.

• Korean Journal of Veterinary Service
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• v.14 no.2
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• pp.159-174
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• 1991

A field trial of norfloxacin on bovine 206, swine 222 and poultry 205 with respiratory diseases and diarrhea was conducted from Sept 1, 1990 to Jan 30, 1991 in Inchon and Kyonggi-do. The results are as follows. 1. Guinea pigs and rabbits were dosages 10 and 20 times normal. Ten days of observation saw no side effect. 2. Oral treatment on bovine, swine and poultry showed a curing rate of 82.00∼89.06%(Mean 86.00%), compared with 87.27∼96.36%(Mean 92.24%) by Injection. 3. The curing rate was 81.92% by the fourth treatment. 4. The curing rate with and without the use of adjuvant was 80.00∼100% and 83.60∼93. 10%, respectively, for swine, and 81.82∼100% and 82.00∼97.14% for bovine. 5. The curing rate was more dependent on seriousness of illness, environment and time than age. 6. The main disease causing bacteria of bovine respiratory diseases： Haemolytic Sta 27.62%, Haemolytic Str 33.33%, sum of this bacteria is 60.95%, diarrhea: Haemolytic coliform 80.20%, swine respiratory diseases； Haemophilus Spp 20.95%, Haemolytic Sta 72%, Haemolytic Str 21.90%, Sum of these bacteria is 68.57％, diarrhea; Haemolytic coliform 57.26%, poultry respiratory diseases； mycoplasma Spp 29.52%, Haemolytic Sta 13.33％, Sum of this bacteria is 42.85%, diarrhea； Haemolytic coliform 53.00%. 7. The curing rate of norfloxacin by species of strain, the unidentified bacteria on bovine respiratory diseases was the lowest with 77.78％, the others ranged from 84.21％ to 100％ with most of them over 90%. 8. The loss of clinical sign on bovine and swine was the highest when after 2∼4 application. 9. In terms of antibiotic sensitivity test, norfloxacin was the highest with 84.62∼100％ (mean 90.09％) among eight bacterias, only 5 of 15 antibiotics had a sensitivity of over 56.25%, showing a high degree of tolerance.

• Applied Chemistry for Engineering
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• v.7 no.6
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• pp.1096-1104
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• 1996

In order to synthesize a new antibacterial and antitumor agents, we have prepared new analogues pteroic acid(13a, 13b), which means C-9 position of pteroic acid has been replaced by norfloxacin(8) or ciprofloxacin(9) and amino group of C-2 position by $CH_3$. These derivatives were synthesized coupling at N-4 piperazine of norfloxacin and ciprofloxacin with 2-amino-3-cyano-5-chloromethylpyrazine(20) provided 1-alkyl(ethyl, cyclopropyl)-6-fluoro-1,4-dihydro-4-oxo-7-[[4-N-(2-amino-3-cyanopyrazin-5-yl)methyl]piperazin-1-yl]-3-quinoline-carboxylic acid(12a, 12b). It was then cyclized with acetamidine. HCI to obtain new analogues of C-2 desaminomethylpteroic acid(13a, 13b) in yield of 76.2% and 82.8 % respectively. These compounds were tested in vitro on antibacterial activity against Gram-positive and Gram-negative bacteria including Pseudomonas aeruginosa ATCC9027. In general, these synthesized compounds(13a, 13b) showed less potent activities than those of norfloxacin.

• Korean Journal of Veterinary Research
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• v.35 no.4
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• pp.683-689
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• 1995

임상적으로 건강한 New Zealand White 종인 수컷 토끼에서 항생제 norfloxacin(NFX)의 체내 동태를 조사하기 위하여 체중 kg당 5mg을 정맥 및 경구 투여하였다. 그 결과 빠른 분포기와 소실기를 갖는 2-콤파트먼트 모델 양상으로 나타났다. 혈장에서의 약물분석은 HPLC로 실시하였는데, 이동상은 acetonitrile/0.01M phosphate buffer/ 10% citric acid 1mM heptane sulfonic acid(10/70/20)이었고, 흡수 파장은 274nm에서 실시하였다. 정맥 투여후, 생물학적 반감기는 3.14시간으로 나타났으며, 분포반감기는 0.38시간으로 빠른 분포를 보여주었다. 최고 혈중농도는 $24.27{\mu}g/ml$로 계산되었으며 청소율은 0.68ml/kg/h로 분석되었다. 경구 투여후, 최고 혈중 농도와 최고 혈중 도달 시간은 $0.86{\mu}g/ml$과 0.43시간으로 각각 계산되었다. 이때의 생물학적 반감기는 3.61시간으로 정맥 투여시와 유의성 있는 차이는 없었으며, 흡수 반감기는 0.17시간으로 빠른 흡수를 보여주었다. 생체이용율은 30%로 나타났으며, 0.2-1.6g/ml인 치료혈중 농도 범위에서 혈장 결합율은 26%로 나타나, 토끼에서 항생요법은 구강 투여시 초기 투여량은 2.71mg/kg이며, 유지 투여량은 12시간마다 2.54mg/kg이 적당한 것으로 분석되었다.