Determination of carbamazepine in human urine and serum samples by high‐performance liquid chromatography with post‐column Ru(bipy)‐Ce(SO4)2 chemiluminescence detection

A novel, sensitive and rapid CL method coupled with high‐performance liquid chromatography separation for the determination of carbamazepine is described. The method was based on the fact that carbamazepine could significantly enhance the chemiluminescence of the reaction of cerium sulfate and tris(2,2‐bipyridyl) ruthenium(II) in the presence of acid. The chromatographic separation was performed on a Kromasil® (Sigma‐Aldrich) TM RP‐C18 column (id: 150 mm × 4.6 mm, particle size: 5 µm, pore size: 100 Å) with a mobile phase consisting of methanol–water‐glacial acetic acid (70:29:1, v/v/v) at a flowrate of 1.0 mL/min, the total analysis time was within 650 s. Under optimal conditions, CL intensity was linear for carbamazepine in the range 2.0 × 10^?8 ~ 4.0 × 10^?5 g/mL, with a detection limit of 6.0 × 10^?9 g/mL (S/N = 3) and the relative standard detection was 2.5% for 2.0 × 10^?6 g/mL (n = 11). This method was successfully applied to the analysis of carbamazepine in human urine and serum samples. The possible mechanism of the CL reaction is also discussed briefly. Copyright © 2012 John Wiley & Sons, Ltd.     

Spectrofluorimetric determination of certain biologically active phenothiazines in commercial dosage forms and human plasma

A validated simple and sensitive spectrofluorimetric method was developed for the determination of chlorpromazine hydrochloride, promethazine hydrochloride, trifluperazine hydrochloride, thioridazine hydrochloride, perazine maleate and oxomemazine. The method was based on condensation of malonic acid/acetic anhydride (MAA) under the catalytic effect of the tertiary amine moiety of the studied phenothiazines to provide a deep yellow to brown colour with green florescence. Relative fluorescence intensity of the products was measured at λ_exc 398 nm and λ_em 432 nm. Different variables affecting the reaction were studied and optimized. The method was successfully applied for the determination of the studied drugs in commercial dosage forms. The lower detection limits allowed the application of this method for the determination of the compounds in plasma as an example of a biological fluid. In addition, the method was considered specific for the determination of tertiary amines in the presence of primary and secondary amines; as a result, it was deemed suitable for the determination of the cited drugs in the presence of their degradation products resulting from N‐dealkylation or oxidation of the corresponding sulphoxides or sulphones. Copyright © 2012 John Wiley & Sons, Ltd.     

Determination of sulpiride in pharmaceutical preparations and biological fluids using a Cr (III) enhanced chemiluminescence method

A highly sensitive and simple method for identifying sulpiride in pharmaceutical formulations and biological fluids is presented. The method is based on increased chemiluminescence (CL) intensity of a luminol–H₂O₂ system in response to the addition of Cr (III) under alkaline conditions. The CL intensity of the luminol–H₂O₂–Cr (III) system was greatly enhanced by the addition of sulpiride and the CL intensity was proportional to the concentration of sulpiride in a sample solution. Various parameters affecting the CL intensity were systematically investigated and optimized for determination of the sulpiride in a sample. Under the optimum conditions, the CL intensity was proportional to the concentration of sulpiride in the range of 0.068–4.0 µg/mL, with a good correlation coefficient of 0.997. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 8.50 × 10^‐6 µg/mL and 2.83 × 10^‐5 µg/mL, respectively. The method presented here produced good reproducibility with a relative standard deviation (RSD) of 2.70% (n = 7). The effects of common excipients and metal ions were studied for their interference effect. The method was validated statistically through recovery studies and successfully applied for the determination of sulpiride in pure form, pharmaceutical preparations and spiked human plasma samples. The percentage recoveries were found to range from 99.10 to 100.05% for pure form, 98.12 to 100.18% for pharmaceutical preparations and 97.9 to 101.4% for spiked human plasma. Copyright © 2012 John Wiley & Sons, Ltd.     

Optimization and validation of spectrofluorimetric method for determination of cefadroxile and cefuroxime sodium in pharmaceutical formulations

A simple, accurate, precise and validated spectrofluorimetric method is proposed for the determination of two cephalosporins, namely, cefadroxile (cefa) and cefuroxime sodium (cefu) in pharmaceutical formulations. The method is based on a reaction between cephalosporins with 1,2‐naphthoquinone‐4‐sulfonate in alkaline medium, to form fluorescent derivatives that are extracted with chloroform and subsequently measured at 610 and 605 nm after excitation at 470 and 460 nm for cefa and cefu respectively. The optimum experimental conditions have been studied. Beer's law is obeyed over the concentrations of 20–70 ng/mL and 15–40 ng/mL for cefa and cefu, respectively. The detection limits were 4.46 ng/mL and 3.02 ng/mL with a linear regression correlation coefficient of 0.9984 and 0.998, and recoveries ranging 97.50–109.96% and 95.73–98.89% for cefa and cefu, respectively. The effects of pH, temperature, reaction time, 1,2‐naphthoquinone‐4‐sulfonic concentration and extraction solvent on the determination of cefa and cefu, have been examined. The proposed method can be applied for the determination of cefa and cefu in pharmaceutical formulations in quality control laboratories. Copyright © 2013 John Wiley & Sons, Ltd.     

Design and Synthesis of Novel Threosyl-5′- Deoxyphosphonic Acid Purine Analogues as Potent Anti-Hiv Agents

The discovery of threosyl phosphonate nucleoside (PMDTA, EC₅₀ = 2.53 μM) as a potent anti-HIV agent has led to the synthesis and biological evaluation of 5 ′-deoxyversions of threosyl phosphonate nucleosides from 1,4-dihydroxy-2-butene. The synthesized nucleoside phosphonic acid analogues 14 and 19 were tested for anti-HIV activity as well as cytotoxicity. The adenine analogue 14 exhibits moderate in vitro anti-HIV-1 activity (EC₅₀ = 12.6 μM).     

Synthesis and Anti-Hiv Activity of 4′-Modified Cyclopentenyl Pyrimidine C-Nucleosides

Novel syntheses of 4′-modified cyclopentenyl pyrimidine C-nucleosides were performed via C-C bond formation using S_N2 alkylation via the key intermediate mesylates 6 and 16, which were prepared from acyclic ketone derivatives. When antiviral evaluation of synthesized compound was performed against various viruses such as HIV-1, HSV-1 and HSV-2, isocytidine analogue 20 showed moderate anti-HIV activity in CEM cell line (EC₅₀ = 13.1 μmol).7     

Overexpression of Neurospora crassa OR74A glutamate decarboxylase in Escherichia coli for efficient GABA production

This study investigated the effect of glutamate decarboxylase from Neurospora crassa OR74A on GABA production in Escherichia coli. GABA is one of the inhibitory neurotransmitters in the mammalian central nervous system, and can be used as a precursor of promising biopolymer Nylon 4. E. coli that overexpressed N. crassa glutamate decarboxylase was cultured at various pH levels and temperatures to determine optimum conditions for GABA production. When the recombinant E. coli strain was cultured at 30°C and pH 3, a final GABA concentration of 5.26 g/L was obtained from 10 g/L of monosodium glutamate (MSG), corresponding to a GABA yield of 86.23%.     

Phylogenetic position of Jaoa,a green algal genus endemic to China

Jaoa prasina, a freshwater green alga endemic to China, was collected from a stream in Hubei province, China. Unialgal cultivation, morphological observation, and phylogenetic analyses of small subunit ribosomal DNA and RuBisCO large subunit sequences were performed. When cultured on agar medium, the alga was irregularly filamentous, similar to marine species of Acrochaete. Aplanospores were observed on solid medium. A vesicular‐like thallus without rhizoids developed in liquid medium, similar to specimen development in natural habitats. Molecular phylogenetic analyses revealed that Jaoa was closely related to the marine genera Acrochaete Pringsheim and Ulvella Crouan & Crouan. The results suggested the genus Jaoa is a member of the family Ulvellaceae (Ulvophyceae), which contains mostly marine algae. The family name Jaoaceae should be abandoned. We speculate that Jaoa may have evolved from a marine Ulvellaceae ancestor.     

When to estimate sex ratio in natural populations of insects? A study on sex ratio variations of gall midges within a generation

Precise estimation of arthropods' sex ratio is an important issue in a wide range of ecological studies and biological control programs. Although, in many cases changes in arthropods' sex ratio may be under the control of parents or some symbiotic microorganisms, biased sex ratios in some other species are caused by some extrinsic factors, neglect of which may lead to under/overestimation of true sex ratio. In this paper, we pursued those factors that cause false estimation of sex ratio in insects' species. We studied the predatory gall midge, Aphidoletes aphidimyza Rondani (Diptera: Cecidomyiidae), an important biological control agent of aphids, that shows protandry (i.e. early male emergence), differential lifespan of sexes, and differential distribution of sexes across habitat. Ten populations of A. aphidimyza were released separately in transparent cages and their sex ratio variations were recorded every 12 hours. The primary sex ratio in this species seems to be slightly male‐biased (52.41% males), however early emergence of males biases the sex ratio up to 72% males in a few hours after emergence. Shortly after the emergence of females, the sex ratio reaches its primary situation, but as a result of male‐biased mortality after mating, the proportion of females increases gradually to 97% by the fourth and fifth days after emergence. These results explicitly suggest that direct estimation of sex ratio in natural populations may be affected by some secondary factors such as differential mortality of sexes, protandry, and differential distribution of males and females over time and/or across habitat.