- Synthesis and antibacterial evaluation of novel 4′-glycyl linked quinolyl-azithromycins with potent activity against macrolide-resistant pathogens
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A new azithromycin-based series of antibacterial macrolones is reported, which features the use of a 4′-ester linked glycin for tethering the quinolone side chain to the macrolide scaffold. Among the analogs prepared, compounds 9e and 22f with a quinolon-6-yl moiety were found to have potent and well-balanced activity against clinically important respiratory tract pathogens, including erythromycin-susceptible and MLSB resistant strains of Streptococcus pneumoniae, Streptococcus pyogenes, and Haemophilus influenzae. In addition, potential lead compounds 9e and 22f demonstrated outstanding levels of activity against Moraxella catarrhalis and inducibly MLSB resistant Staphylococcus aureus. The best member of this series 22f rivals or exceeds, in potency, some of the most active ketolide antibacterial agents known today, such as telithromycin and cethromycin.
- Pavlovi?, Dra?en,Mutak, Stjepan
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- Ciprofloxacin degradation in UV/chlorine advanced oxidation process: Influencing factors, mechanisms and degradation pathways
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Ciprofloxacin (CIP) is a widely used third generation fluoroquinolone antibiotics, and has been often detected in wastewater treatment plants. Finding an effective way to remove them from wastewater is of great concern. Ultraviolet (UV)/chlorine advanced oxidation process (AOP) has many advantages in micropollutant removal. In this study, CIP degradation in UV/chlorine process was investigated. Only 41.2% of CIP was degraded by UV photolysis and 30.5% by dark chlorination in 30 min, while 98.5% of CIP was degraded by UV/chlorine process in 9 min. HCO3 ? had markedly inhibition, NO3 ? and SO4 2- had slight inhibition, and Cl? had a marginal inhibition on CIP degradation in UV/chlorine system. The degradation of CIP in UV/chlorine process was mainly attributed to the attack of reactive species. The relative contributions of hydrated electrons (eaq [rad]), hydroxyl radicals (HO[rad]), chlorine atoms (Cl[rad]), and UV photolysis were investigated. Under neutral condition in aqueous solution, CIP degradation had highest pseudo first-order reaction rate constant, in which eaq [rad] had the highest contribution, followed by Cl[rad], HO[rad], and UV photolysis. The intermediates and byproducts were identified and the degradation pathway was proposed. The total organic chlorine (TOCl) and biotoxicity were further assessed. CIP and natural organic matters (NOMs) were removed efficiently in real water. UV/chlorine showed the potential for the wastewater treatment containing CIP.
- Deng, Jia,Wu, Guangxue,Yuan, Shoujun,Zhan, Xinmin,Wang, Wei,Hu, Zhen-Hu
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- Nitric oxide reactivity accounts for N-nitroso-ciprofloxacin formation under nitrate-reducing conditions
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The formation of N-nitroso-ciprofloxacin (CIP) was investigated both in wastewater treatment plants including nitrification/denitrification stages and in sludge slurry experiments under denitrifying conditions. The analysis of biological wastewater treatment plant effluents by Kendrick mass defect analysis and liquid chromatography - high resolution - mass spectrometry (LC[sbnd]HRMS) revealed the occurrence of N-nitroso-CIP and N-nitroso-hydrochlorothiazide at concentration levels of 34 ± 3 ng/L and 71 ± 6 ng/L, respectively. In laboratory experiments and dark conditions, produced N-nitroso-CIP concentrations reached a plateau during the course of biodegradation experiments. A mass balance was achieved after identification and quantification of several transformation products by LC[sbnd]HRMS. N-nitroso-CIP accounted for 14.3% of the initial CIP concentration (20 μg/L) and accumulated against time. The use of 4,5-diaminofluorescein diacetate and superoxide dismutase as scavengers for in situ production of nitric oxide and superoxide radical anion respectively, revealed that the mechanisms of formation of N-nitroso-CIP likely involved a nitrosation pathway through the formation of peroxynitrite and another one through codenitrification processes, even though the former one appeared to be prevalent. This work extended the possible sources of N-nitrosamines by including a formation pathway relying on nitric oxide reactivity with secondary amines under activated sludge treatment.
- Brienza, Monica,Chiron, Serge,Manasfi, Rayana,Sauvêtre, Andrés
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- Ciprofloxacin degradation from aqueous solution by Fenton oxidation: Reaction kinetics and degradation mechanisms
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Pharmaceutical wastewater from a large number of manufacturing units is extremely contaminated by ciprofloxacin (CIP), an antibiotic drug. In this work, aqueous CIP solution was treated by Fenton oxidation (FO). The effects of typical process parameters on drug mineralization have been reported. The optimal Fe2+/H2O2 molar ratio of 0.125 and pH of 3.5 were determined with 15 mg L-1 initial CIP at 25°C temperature. Maximum CIP, COD and TOC removal of 74.4, 47.1 and 37.9% were obtained under the optimal conditions. The mean oxidation number of carbon determined in terms of COD and TOC values was in accordance with that from the oxidation number of individual carbon atom. The concentration of hydroxyl radicals was measured using the N,N-dimethyl phenyl hydrazine method using dimethyl sulphoxide as a probe. Thirteen fragments appeared in the mass spectra and the proposed mechanism explored the routes of daughter ion formation. The cleavage of the piperazine ring was more effective in CIP oxidation due to high nucleophilic character of lone pair of electrons present on the nitrogen atom. A simple 2nd order kinetic model was proposed for the oxidation of CIP and degradation products (DPs) with respect to OH concentration. The rate constants of 3.13 × 103, 4.89 × 103 M-1 s-1 were estimated for CIP and DPs. The initial concentration of OH was found to be 11.67 μM.
- Giri, Ardhendu Sekhar,Golder, Animes Kumar
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p. 6738 - 6745
(2014/02/14)
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- Photochemistry of 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(piperazin-1-yl)quinoline-3- carboxylic acid (=ciprofloxacin) in aqueous solutions
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The 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(piperazin-1-yl)quinoline-3- carboxylic acid (=ciprofloxacin; 1) undergoes low-efficiency (φ=0.07) substitution of the 6-fluoro by an OH group on irradiation in H2O via the ππ* triplet (detected by
- Mella, Mariella,Fasani, Elisa,Albini, Angelo
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p. 2508 - 2519
(2007/10/03)
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- Stability study of ciprofloxacin hydrochloride using reversed phase HPLC
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In this study, the stability properties of ciprofloxacin hydrochloride were investigated with the aim at formulating hard capsules. A HPLC method is presented and validated for the determination of this molecule and its degradation products. This procedure is a modified method of the European Pharmacopoeia. The analysis has been performed on a Lichrospher RP-18 column at 40 °C with UV detection at 278 nm. The mobile phase was methanol/phosphoric acid 0.245% in water first adjusted to pH 3.0 with triethylamine (12:88, v/v). The results have shown that the molecule studied is proof against heat and humidity but is slightly sensitive to photodegradation. The main degradation product identified is the desethyleneciprofloxacin.
- Hudrea,Grosset,Alary,Bojita
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p. 516 - 519
(2007/10/03)
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- Isolation and structural elucidation of urinary metabolites of ciprofloxacin
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After oral administration of 1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-piperazine-1-ylqu inoline-3-carboxylic acid (ciprofloxacin, Bay o 9867; designated trademark: Ciprobay) four metabolites M1-M4 were isolated from human urine by Craig counter current distribution and semipreparative high-performance liquid chromatography. Their molecular structures were elucidated by nuclear magnetic resonance and mass spectrometry and confirmed by comparing their spectra with those of authentic synthetic reference compounds.
- Gau,Kurz,Petersen,Ploschke,Wuensche
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p. 1545 - 1549
(2007/10/02)
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