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Bassyouni Fatma A. Tawfik Hanaa A. Soliman Abdel Mohsen Rehim Mohamed Abdel 《Research on Chemical Intermediates》2017,43(7):4311-4311
Research on Chemical Intermediates - 相似文献
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Mohamed R. Elghobashy Lories I. Bebawy Samah S. Abbas Rafeek F. Shokry 《Chromatographia》2013,76(17-18):1141-1151
Two sensitive and selective stability-indicating methods were developed for the determination of the antibiotic cefpirome sulfate in bulk powder, pharmaceutical formulation and in presence of its acid, alkaline, photo- and oxidative degradation products. Method A was based on HPLC separation of cefpirome sulfate in the presence of its degradation products on a reversed phase column C18, 250 × 4.6 mm, 5-μm particle size and mobile phase consisting of 0.1 M disodium hydrogen phosphate dihydrate pH 3.9 adjusted with phosphoric acid–acetonitrile (85:15, v/v). Quantitation was achieved with UV detection at 270 nm. The linear calibration curve was in the range 5.0–50.0 μg mL?1. Method B was based on reversed phase TLC separation of the cited drug in the presence of its degradation products followed by densitometric measurement of the intact drug at 270 nm. The separation was carried out using disodium hydrogen phosphate dihydrate 2.0 g %w/v, at pH 3.5 adjusted with phosphoric acid–acetone (15:10, v/v) as a developing system. The calibration curve was in the range of 1.0–10.0 μg/spot. The HPLC method was used to study the kinetic of cefpirome sulfate acid degradation. The results obtained were statistically analyzed and compared with those obtained by applying the official Japanese method. 相似文献
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Mashooq A. Bhat Ahmed M. Naglah Siddique Akber Ansari Hanaa M. Al-Tuwajiria Abdullah Al-Dhfyan 《Molecules (Basel, Switzerland)》2021,26(12)
A ChCl: Gly (DESs) promoted environmentally benign method was developed for the first time using the reaction of aryl aldehydes and dimedone to give excellent yields of xanthene analogues. The major application of this present protocol is the use of green solvent, a wide range of substrate, short reaction times, ease of recovery, the recyclability of the catalyst, high reaction yield, and ChCl: Gly as an alternative catalyst and solvent. In addition to this, all the synthesized compounds were evaluated for their in vitro antimycobacterial activity against M. tuberculosis H37Ra (MTB) and M. bovis BCG strains. The compounds 3d, 3e, 3f, and 3j showed significant antitubercular activity against MTB and M. bovis strains with minimum inhibitory concentration (MIC) values of 2.5−15.10 µg/mL and 0.26–14.92 µg/mL, respectively. The compounds 3e, 3f, and 3j were found to be nontoxic against MCF-7, A549, HCT 116, and THP-1 cell lines. All the prepared compounds were confirmed by 1H NMR and 13C NMR analysis. 相似文献
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Validated spectrophotometric and fluorimetric methods for analysis of clozapine in tablets and urine
Five spectrophotometric methods and one fluorimetric method have been developed and validated for the analysis of clozapine. The spectrophotometric methods were based on the charge-transfer complexation reaction between clozapine as electron donor and each of iodine as sigma-acceptor or 7,7,8,8-tetracyanoquinondimethane (TCNQ), 2,3-dichloro-5,6-dicyano-1,4-benzo-quinone (DDQ), tetracyanoethane (TCNE), and p-chloranilic acid (pCA) as pi-acceptors. The obtained complexes were measured spectrophotometrically at 365, 843, 460, 414, and 520 nm for iodine, TCNQ, DDQ, TCNE, and pCA, respectively. The fluorimetric method was based on the oxidation of clozapine in the presence of perchloric acid by cerium (IV), and subsequent measuring the fluorescence of the produced cerium (III) fluorimetrically at lambda(excitation) 260 and lambda(emission) 355 nm. Under the optimum assay conditions, Beer's law was obeyed at concentrations ranged from 4-200 microg mL(-1) for the spectrophotometric methods and from 24-250 ng mL(-1) for the fluorimetric method. The limits of detection for the spectrophotometric methods were 1.12, 1.76, 2.22, 0.95, and 13.26 microg mL(-1) for iodine, TCNQ, DDQ, TCNE, and pCA, respectively. The limit of detection for the fluorimetric method was 6.69 ng mL(-1). The proposed methods were successfully applied to the analysis of clozapine in tablets with good recoveries. The fluorimetric method could also be applied to the analysis of clozapine in spiked urine samples. The molar ratios and the reaction mechanisms were investigated. 相似文献
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Mohammed M. Ghoneim Ibrahim S. El-Hallag Kamal Y. El-Baradie Hanaa S. El-Desoky Mona A. El-Attar 《Monatshefte für Chemie / Chemical Monthly》2006,137(3):285-299
Summary. The electrochemical behavior of some hydrazones derived from 6-chloro-2-hydrazinopyridine in the Britton-Robinson universal buffer of pH 2–11 containing 35% ethanol was investigated at the mercury electrode using dc-polarography, controlled-potential coulometry,
and cyclic voltammetry techniques. The examined hydrazones were reduced in solutions of pH < 9 in a single 4-electron diffusion-controlled irreversible step corresponding to both the saturation of –N=C< double bond
and cleavage of the –HN–NH– single bond of the hydrazone molecule via the consumption of two electrons for each center. Whereas the starting compound, 6-chloro-2-hydrazinopyridine, was reduced
in a single 2-electron diffusion-controlled irreversible step corresponding to cleavage of its –NH–NH2 single bond. The mechanistic pathway of the electrode reaction of the studied compounds was elucidated and discussed. The
pKa values of the examined hydrazones and the stoichiometry of their complexes in solution with some transition metal ions were
determined spectrophotometrically. The dissociation constants and the thermodynamic parameters of the investigated hydrazones,
and the stability constants of their metal complexes in solution were determined potentiometrically. 相似文献
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Ion-exchange LC and spectroscopic supporting techniques have been successfully used to study the kinetics and mechanism of oxidation reactions of selenomethionine (SeMet). Oxidation of selenomethionine with both cyanogen bromide (CNBr) and hydrogen peroxide (H2O2) proceeds through a stable intermediate which undergoes cyclization and C-Se bond cleavage to form 2-amino-4-butyrolactone. This stable intermediate was identified by IR spectroscopy as methionine dihydroxy selenide. The CH3-Se moiety of SeMet formed methyl selenic acid upon reaction with H2O2 and methyl selenocyanate (CH3SeCN), characterized by GC-MS, for the reaction with CNBr. Both reactions were of apparent first order with respect to the concentration of SeMet. A rate constant (k1)of 4.0×10–3 s–1 for the reaction of SeMet with HO and 4.0×10–3 s–1 for the reaction with CNBr were determined at a temperature of 22°C. Oxidation of methionine (Met) gives disparate kinetics and oxidation products from SeMet. Thus the differential rate method can be utilized to quantitatively separate SeMet in biological samples in the presence of much higher concentrations of Met. 相似文献
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Walaa S. El‐serwy Hanaa S. Mohamed Weam S. El‐serwy Neama A. Mohamed Emad M. M. Kassem Eman S. Nossier Al Shimaa G. Shalaby 《Journal of heterocyclic chemistry》2019,56(7):2027-2035
A new series of thiopyrimidine‐5‐carbonitrile derivatives were synthesized and the chemical identity of them was established on the basis of spectral methods. The antimicrobial properties of all derivatives were investigated against Gram‐positive and Gram‐negative bacteria as well as fungal strains. The results of the antimicrobial screening showed that compounds 4 , 11 , and 12 have a higher and broad spectrum efficacy against all the tested organisms in comparison with the reference drugs. Interestingly, the most active compounds 4 and 12 showed good binding assay results with Escherichia coli DNA gyrase comparable to that of the reference, methotrexate. Furthermore, a molecular docking study of these compounds was carried out to investigate their binding pattern with the target, DNA gyrase. 相似文献
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JPC – Journal of Planar Chromatography – Modern TLC - The discovery of new direct-acting antiviral drugs gave rise to a leap forward in the treatment of hepatitis C viral infections.... 相似文献