Efficient syntheses of novel indeno[1,2-b]chromenone derivatives via hetero-Diels-Alder reactions of 2-(arylmethylene)-1H-indene-1,3(2H)-diones with enaminones

Efficient syntheses of novel 10-aryl-5a-(arylamino)-9-hydroxy-5a,6,7,8-tetrahydroindeno[1,2-b]chromen-11(10H)-one derivatives has been reported by [4+2] cycloaddition reactions of electron-deficient 2-(arylmethylene)-1H-indene-1,3(2H)-dione heterodienes with electron-rich enaminones in [bmim]BF₄ at 80?°C and in acetic acid at 80?°C. Dimedone/cyclohexane-1,3-dione enaminones have been used as dienophiles in Inverse Electron Demand hetero-Diels-Alder reactions. The products were obtained in high yields by a simple work up.     

Synthesis, <Emphasis Type="Italic">β</Emphasis>-<Emphasis Type="Italic">Glucuronidase</Emphasis> Inhibition,and Molecular Docking Studies of 1,2,4-Triazole Hydrazones

A series of 1,2,4-triazole hydrazones 1–25 has been synthesized and characterized using different spectroscopic techniques including FT-IR, ¹H-NMR, and ESI MS spectrometry. The synthetic derivatives were evaluated for their β-glucuronidase enzyme inhibition properties. Among them, 17 compounds demonstrated potential inhibitory activity towards β-glucuronidase with IC₅₀ values ranging between 2.50 and 53.70 µM. Compounds 1 having IC₅₀?=?2.50?±?0.01 µM was found to be the most active compound of the series and showed remarkable activity and found to be far more potent than the standard d-saccharic acid 1,4-lactone (IC₅₀?=?48.4?±?1.25 µM). Furthermore, the possible binding interaction of active compounds was explored by in silico studies. These compounds can be used for anti-diabetic drug development process.     

Cu-assisted C–N bond formations in six-membered N-heterocycle synthesis

Abstract

One of the highly emerging and important aspect of organic chemistry is the metal-catalyzed synthesis of the heterocycles. The methodologies used earlier for its synthesis were less approachable to the organic chemist because of their high cost, highly specified instrumentation and inconvenient methods. For both the stereoselective and regioselective synthesis of six-membered nitrogen-containing heterocycles, cyclic reactions that are Cu-catalyzed have known to be very efficient. The presented review covers the varied applications of Cu as a catalyst and its importance in the formation of six-membered nitrogen-containing heterocycles. The fascinating research that has been done in this area is also enclosed in this review.     

Photocatalytic reduction of CO2 over Cu-TiO2 /molecular sieve 5A composite

TiO(2) and different Cu wt% loaded TiO(2) (TC(0.5-5.0)), 10 wt% TC(2.0) supported on molecular sieve 5A (10 wt% TC(2.0)/MS) were prepared by impregnation and solid-state dispersion methods. The photocatalysts prepared were characterized using XRD, SEM, and UV-Vis DRS, TEM, XPS spectroscopy techniques. Photocatalytic reduction of CO(2) in water and alkaline solution are investigated in a batch reactor. The yield of oxalic acid increased notably when TC was supported on molecular sieve. The Cu-TiO(2) supported on molecular sieve catalyst promotes the charge separation that leads to an increase in the selective formation of oxalic acid in addition to methanol, acetic acid and traces of methane. The product formation is due to the high adsorption of CO(2), water and product shape selectivity of the composite photocatalyst. The maximum yield of oxalic acid was found to be 65.6 μg h(-1) g(-1) per cat using 0.2 N NaOH containing solution over 10 wt% TC(2.0)/MS photocatalyst. The difference in the photocatalytic activity is related to its physicochemical properties.     

A rapid and sensitive LC-MS/MS method for quantification of donepezil and its active metabolite, 6-o-desmethyl donepezil in human plasma and its pharmacokinetic application

A rapid and sensitive liquid chromatography–tandem mass spectrometric (LC‐MS/MS) assay method has been developed and fully validated for simultaneous quantification of donepezil and its active metabolite, 6‐o‐desmethyl donepezil in human plasma. Analytes and the internal standard were extracted from human plasma by liquid–liquid extraction technique using a 30:70 v/v mixture of ethyl acetate and n‐hexane. The reconstituted samples were chromatographed on a C₁₈ column by using a 70:30 v/v mixture of acetonitrile and ammonium formate (5 mm , pH 5.0) as the mobile phase at a flow rate of 0.6 mL/min. The calibration curve obtained was linear (r ≥ 0.99) over the concentration range of 0.09–24.2 ng/mL for donepezil and 0.03–8.13 ng/mL for 6‐o‐desmethyl donepezil. The results of the intra‐day and inter‐day precision and accuracy studies were well within the acceptable limits. The proposed method was successfully applied for the estimation of the drug in real time plasma samples for pharmacokinetic studies. Copyright © 2010 John Wiley & Sons, Ltd.     

Evaluation of Anthocyanin Content,Antioxidant Potential and Antimicrobial Activity of Black,Purple and Blue Colored Wheat Flour and Wheat-Grass Juice against Common Human Pathogens

The present study aimed to analyze the antioxidant and antimicrobial activity of anthocyanins extracted from colored wheat flour and wheat-grass juice against human pathogens. The total anthocyanin content and antioxidant potential in colored wheat flour and wheat-grass juice extracts were significantly higher than white flour and wheat-grass juice extracts. Ultra-performance liquid chromatography showed the maximum number of anthocyanin peaks in black wheat, with delphinidin-3-o-galactoside chloride, delphinidin-3-o-glucoside chloride, and cyanindin-3-o-glucoside chloride as the major contributors. Among flour extracts, maximum zones of inhibition against Staphylococcus aureus (MTCC 1934), Pseudomonas aeruginosa (MTCC 1434), Escherichia coli, and Candida albicans (MTCC 227) were produced by black flour extract, having the highest anthocyanin content. It exhibited a minimum microbicidal concentration (MMC) of 200 mg/mL against E. coli and C. albicans; and 100 and 150 mg/mL against S. aureus and P. aeruginosa, respectively. Black and purple flour extracts exhibited a minimum inhibitory concentration (MIC) of 50 mg/mL against S. aureus and P. aeruginosa. White flour extracts did not show MMC against E. coli and C. albicans. Among wheat-grass juice extracts, black wheat-grass was most effective and showed an MIC of 100–150 mg/mL against all pathogens. It exhibited an MMC of 200 mg/mL against S. aureus and P. aeruginosa. Hence, anthocyanin-rich colored wheat could be of nutraceutical importance.     

ESR study of exchange coupled pairs in copper diethyldithiocarbamate

ESR investigations on exchange coupled pairs of Cu ions in single crystals of Cu(dtc)₂, isomorphously diluted with the corresponding diamagnetic zinc salt, are reported. The spin Hamiltonian parameters for the coupled species (S=1) are:g _‖=2.1025,g ₊=2.031,A=75.1×10⁻⁴ cm⁻¹,B=14.8×10⁻⁴,D=276.0×10⁻⁴ cm⁻¹ andE=46.7×10⁻⁴ cm⁻¹. While theg andA tensors show tetragonal symmetry, the zeor-field splitting tensor is rhombic and has principal axes different from those of theg andA tensors. Intensity measurements made down to 4.2 K indicate that the exchange is ferromagnetic with |FFF| ∼ 10 cm⁻¹. Direct dipole-dipole interaction appears to be the major contribution to the zero-field splitting. A calculation on the distributed point dipole model shows that dipolar interaction is considerably modified by the high covalency of the Cu-S bond and accounts for the rhombic nature of the tensor. The possible exchange mechanisms in Cu(dtc)₂—direct exchange and superexchange through the bridging sulphurs—are discussed.     

A model for the pressure dependence of diffusion in condensed matter

In the present paper, a model has been used to develop a simple relation to study the pressure dependence of self-diffusion in solids and liquids that has two adjustable parameters. The computation done in each substance is found to be in very good agreement with the experimental data. It is interesting to note that the present relation is also capable of giving the activation volume in solids and liquids. The activation volume computed in the solids is found to be in very good agreement with the data available.     

Effect of electric field on reentrance transition in a binary mixture of liquid crystals

Employing a phenomenological mean field theory, we analyze the effect of an electric field on the N ? SmA phase transition for pure liquid crystal and on the reentrant nematic phase in a binary mixture of liquid crystals exhibiting the phase sequence I ? N ? SmA ? N_R on cooling. The basic idea of the work is to explain the phase transition behavior of the system by assuming that certain Landau coefficients associated with the order parameters coupling terms of the free-energy density expansion are field dependent. These parameters play a crucial role and show a rapid variation at the SmA ? N_R transition as compared to the SmA ? N transition.