多肽分子中C-末端酰胺化氨基酸残基的鉴定

本文报道了一种新的鉴定多肽分子C-末端酰胺化氨基酸残基的方法,17种酰胺化氨基酸的DABTC衍生物标准品在高效液相色谱上得到充分分离与鉴定,采用上述方法对多肽激素TRH、LHRH、SP及PLG中的C-末端酰胺化氨基酸残基的鉴定同样得到满意结果。

二氧化碳超临界流体代替水作介质铬鞣及其机理的研究(1)——铬鞣机理印证性研究

为了更好地了解在二氧化碳超临界流体下铬鞣机理 ,采用对比实验法对常规铬鞣的基本原理进行了印证性研究。采用传统的皮胶原氨基酰胺化和羧基酯化来确定铬配合物分子与皮胶原结合的反应基团。

Catalytic role of Cu(I) species in Cu_2O/CuI supported on MWCNTs in the oxidative amidation of aryl aldehydes with 2-aminopyridines

Cu2O and Cul were supported on multiwalled carbon nanotubes （MWCNTs） using a wet impregna- tion method, and the resulting materials were fully characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy, transmission electron microscopy, and temperature-programmed desorption with ammonia analysis. The results of these experiments revealed that Cu2O and CuI were deposited on the MWCNTs in the cubic and γ phases, respectively. These results also showed that the Cu-containing MWCNTs exhibited weak to strong electron-accepting （Lewis acidic） properties. The catalytic activities of these materials were studied for the synthesis of biologically significant N-（pyridin-2-yl）benzamides via the oxidative amidation of aryl aldehydes with 2-aminopyridines. The yields of the products were in the range 50%-95% with 100% selectivity. Notably, the CuI/MWCNT catalyst was much more effective than the Cu2O/MWCNT catalyst with respect to the isolated yield of the product, although the latter of these two catalysts exhibited much better recyclability. A preferential interaction was observed between the polar nature of the acid-activated MWCNTs and the ionic Cu2O compared with covalent CuL The differences in these interactions had a significant impact on the rate of the nucleophilic attack of the amino group of 2-aminopyridine substrate on the carbonyl group of the aryl aldehyde.

Intermediate formation enabled regioselective access to amide in the Pd-catalyzed reductive aminocarbonylation of olefin with nitroarene

An efficient route for the palladium-catalyzed reductive aminocarbonylation of olefins with nitroarenes was developed using carbon monoxide(CO)as both reductant and carbonyl source,which enables facile access to amides with excellent regioselectivity and broad substrate scope.It is found that the counter anions of the Pd catalyst precursors significantly affect the reaction chemoselectivity and amide regioselectivity.Branched amides were mainly obtained with K2PdCl4 as the metal catalyst,and phosphine ligands had no influence on the regioselectivity but affected the catalytic reactivity.However,phosphine ligands had significant effects on aminocarbonylation regioselectivity when Pd(CH3CN)4(OTf)2 was used;monodentate phosphines tended to form branched amides,and bidentate phosphines mainly formed linear amides.Trapping experiments,primary kinetic studies,and control reactions with all possible N-species reduced from nitroarene indicated that the catalytic synthesis of branched and linear amides produced nitrene(further converted to enamide)and aniline,respectively,different from the previous ligand-controlled regioselective synthesis of amides via the aminocarbonylation of olefins with amines.Furthermore,the proposed synthesis route could be applied in the synthesis of gram-scale propanil under mild conditions.

Antioxidative and antiapoptotic effects of （＋）-clausenamide on acetaminophen-induced nephrotoxicity in mice

Objective： （＋）-Clausenamide （（＋）-CLA）, the active ingredient of wampee, was isolated from the leaves of Clausena lansium （Lour.） Skeels. This study aimed to evaluate the protective potential of （＋）-CLA against acetaminophen （APAP）-induced nephrotoxicity in mice. Methods： Mice were divided into control, APAP, high-dose （＋）-CLA, and low-dose （＋）-CLA groups. Then, mice were preadministered （＋）-CLA （50 and 100 mg/kg） for 5 consecutive days. After the last treatment, the animals received a single intraperitoneal injection of APAP （600 mg/kg）. Renal histopathology was evaluated by staining with hematoxylin and eosin. The levels of malondialdehyde （MDA） and glutathione （GSH） and the activities of catalase （CAT） and superoxide dismutase （SOD） were determined using corresponding kits. Western blotting was used to analyze the expression of apoptosis-related proteins in renal tissue. Results： Administration of APAP increased serum creatinine and blood urea nitrogen levels in comparison with the control group. An increase in renal MDA level, depletion of GSH, and reductions in CAT and SOD activities in renal tissue indicated that APAP-induced kidney injury was mediated by oxidative stress. The expressions of Bax and caspase-3, cleavage of caspase-3, and cytoplasm cytochrome c levels were up-regulated in renal tissue, whereas Bcl-2 expression and mitochondrial cytochrome c levels were down-regulated in the APAP group, which revealed that APAP-induced kidney injury significantly increased cell apoptosis in renal tubules. The histopathology of kidney tissue supported these biochemical mechanisms. （＋）-CLA can reverse changes in most of the abovementioned parameters and nearly restore the normal structure of the kidney. Conclusion： Oxidative stress and apoptosis are considered to be the mechanisms underlying APAP-induced nephrotoxicity. （＋）-CLA could be a promising antidote for APAP-induced acute renal damage owing to its antioxidative and antiapoptotic effects.

Palladium-catalyzed intermolecular C–H amidation of indoles with sulfonyl azides

A new kind of intermolecular indole C–H amidation reaction catalyzed by the most frequently used palladium catalyst has been developed.Sulfonyl azide was employed as an innovative nitrogen source and environmentally benign nitrogen was produced as the only byproduct.