Evaluation of lipid peroxidation inhibition and free radical scavenging abilities of 5,6,7-trimethoxy dihydroflavonols

Four naturally rare 5,6,7-trimethoxy-2,3-cis-dihydroflavonols(3-6) and two 5,6,7-trimethoxy-2,3-trans-dihydroflavonols(7-8) were designed and synthesized.Their antioxidative properties were evaluated by way of examining their scavenging capacities towards DPPH and O_2~(·-) free radicals,as well as by measuring their inhibitory ability against LPO.Both the 2,3-trans and the 2,3- cis conformers exhibited certain quenching abilities to DPPH and O_2~(·-) radicals,while most of the synthetic dihydroflavonols ...     

SYNTHESIS OF AN AMPHIPHILIC PPESK-g-P(PEGMA) GRAFT COPOLYMER VIA ATRP AND ITS USE IN BLEND MODIFICATION OF PPESK MEMBRANES

Preparation of an amphiphilic graft copolymer having poly(phthalazinone ether sulfone ketone)(PPESK) as main chains was carried out by atom transfer radical polymerization(ATRP).The precursor,chloromethylated PPESK (CMPPESK),was prepared by using chioromethylether as chloromethylation agent.Then,poly(ethylene glycol) methyl ether methacrylate(PEGMA) was used as monomer to synthesize PPESK-g-P(PEGMA) by ATRP method under the catalysis of a cuprous chloride/2,2'-bipyridyl system.PPESK/PPESK-g-P(PEGMA) blen...     

Efficient synthesis of 5,6-dihydrothieno[3′,2′:4,5]-thieno[2,3-d]pyrimidin-4(3H)-ones via an iminophosphorane

5,6-Dihydrothieno[3′,2′:4,5]thieno[2,3-d]pyrimidin-4(3H)-ones 6 were synthesized in yields of 71-87%by a consecutive method,which includes aza-Wittig reaction of iminophosphorane 3 with aromatic isocynate to give carbodiimide 4 and subsequent reaction of 4 with various amines,phenols or alcohols in the presence of catalytic amount of sodium ethoxide or solid potassium carbonate.     

Synthesis of new 2-aryl-6-styryl-2,3-dihydropyridin-4(1H)-one derivatives from curcuminoids

Series of new 2-aryl-6-styryl-2,3-dihydropyridin-4(1H)-one derivatives were synthesized in acceptable to good yields by treatment of the curcuminoids with aqueous ammonia,the mechanism was proposed.By modification of the primary products,total 13 new compounds were obtained.The structures of all products were elucidated by spectroscopy analysis including HR-MS,~1H NMR and ~(13)C NMR.     

Preparation of novel chiral stationary phase based on click chemistry for ligand exchange chromatography

Click chemistry was applied to immobilize L-proline derivative onto azide-modified silica gel to give a novel chiral stationary phase(denoted as click-CSP) for ligand exchange chromatography.The developed protocol combines the benefits of operational simplicity,exceptionally mild conditions and high surface loadings.The enantioselectivityαof some DL-amino acids on the click-CSP were found to be in the range from 1.13 to 3.46.The chromatographic resolutions of some DL-amino acids and the stability study f...     

Screening and docking studies of natural phenolic inhibitors of carbonic anhydrase Ⅱ

Carbonic anhydrase Ⅱ (CAⅡ) is an important enzyme complex with Zn2+,which is involved in many physiological and pathological processes, such as calcification, glaucoma and tumorigenicity. In order to search for novel inhibitors of CAⅡ, inhibition assay of carbonic anhydrase Ⅱ was performed, by which seven natural phenolic compounds, including four phenolics (grifolin, 4-O-methyl-grifolic acid, grifolic acid, and isovanillic acid) and three flavones (eriodictyol, quercetin and puerin A), showed in-hibitory a...     

A new tripodal rhodamine B derivative as a highly selective and sensitive fluorescence chemosensor for copper(Ⅱ)

A new tripodal rhodamine B derivative 2 was designed and synthesized by tripodal trialdehyde and rhodamine B hydrazide for the first time. This derivative could be used as a fluorescent chemosensor for the selective and sensitive determination of copper(II) in Tris-HCl buffer and ethanol aqueous mixed media. Under the optimum conditions described herein,fluorescence enhancement at 557/577 nm was linearly related to the concentration of copper(II) in the range of 0.10 to 10.00×10-5 mol·L-1,with a corre-latio...     

Synthesis and photochromic properties of WO_3 powder induced by oxalic acid

Tungsten trioxide powder with the novel morphology was prepared via the hydrothermal method with oxalic acid as the organic inducer, the structure and shape of which were detected by X-ray diffraction (XRD), scanning electron microscopy (SEM) and BET. Furthermore, photochromic properties of the as-prepared powder samples were tested by an ultraviolet-visible spectrophotometer combined with a color difference meter. The corresponding results indicated that the induced product was still hexagonal WO3, made up...     

Colorimetric and electrochemical Pb~(2+) detection by imine-bridged tetrathiafulvalene-pyridine derivatives

Imine-bridged TTF-π-pyridine derivatives, 2NTTF, 3NTTF and 4NTTF, were synthesized and the cation-binding study was performed. It is noted that with the addition of the micromolar concentration of Pb2+ to the solution, these compounds display remarkable changes in solution color, 1H NMR spectra and electrochemical properties. The nitrogen atom of the imine-bridge in 2NTTF not only serves as a π-conjugated spacer but also participates in the sensing and coordinating properties.     

Application of potassium ferricyanide in the spectrophotometric determination of captopril

A novel method for the determination of captopril by speetrophotometer is described in this paper. The experiment is based on the fact that Fe(Ⅲ) is reduced to Fe(Ⅱ) by captopril, then the in situ formed Fe(Ⅱ) reacts with potassium ferricyanide to give the soluble prussian blue at pH 4.00, and its maximal adsorption wavelength (λmax) is 735 nm. Good linear relationship is obtained between the absorbance and the concentration of captopril in the wide range of 0.05-20 μg/mL. The linear regression equation is A = -0.04314 + 0.11423C (μg/mL) with a correlation coefficient R = 0.9998. The detection limit (3a/k) is 0.04 μg/mL, the molar absorption coefficient is 2.5×104 L/mol cm. By mensurating the absorbance of soluble prussian blue, the indirect determination of eaptopril can be obtained. This method has been successfully applied to determination of captopril in pharmaceutical samples.Analytical results obtained are satisfactory.