Synthesis of a novel 18β-glycyrrhetinic acid derivative

A novel compound, biotinylated 18β-glycyrrhetinic acid (BGA), was synthesized. It is a compound of 18β-glycyrrhetinic acid linked with biotin. Published in Khimiya Prirodnykh Soedinenii, No. 3, pp. 266–267, May–June, 2006. An erratum to this article is available at .     

硅酸及其盐的研究 ⅩⅩⅠ.三甲基硅烷化-气相色谱法测定单硅酸的离解常数

单硅酸的离解常数是表征其基本性质的重要数据,前人已有不少工作,但由于测定的方法和实验条件不同,所得数据很不一致。     

Unusual ion pairs and their relationship to acid ionization

Osmotic and activity coefficients, determined from isopiestic measurements, are presented for aqueous solutions of eight tetramethylguanidinium salts. It is proposed that both hydronium and tetramethylguanidinium ions are capable of forming stable ion pairs with many anions by means of bridged hydrogens forming six-membered rings and that these ion pairs are stable in rather dilute aqueous solutions.     

Synthesis,Spectroscopic Properties and Crystal Structural Characterization of a Triphenyltin(IV) Complex with 5-Bromonicotinic Acid

1 INTRODUCTION Organotin esters of carboxylic acids are widely used as biocides, fungicides and homogeneous ca- talysts in industry[1～3]. Recently, pharmaceutical pro- perties of organotin esters of carboxylic acids have been investigated for their antitumour activity[4, 5]. Studies on organotin compounds containing car- boxylate ligands with additional donor atoms (e.g. N, O or S) that are available for coordination to the tin atom have revealed that new structural types may lead to di…     

牛血清白蛋白与十二烷基硫酸钠作用的机理

利用电动势法得到了牛血清白蛋白(BSA)与十二烷基硫酸钠(SDS)相互作用的结合等温线. 通过四阶导数紫外光谱法和荧光光谱法研究了相互作用过程中芳香族氨基酸残基微环境极性的变化. 通过研究发现, 随着SDS浓度的逐渐增大, SDS在BSA上的平均结合数(v)逐渐增大, 色氨酸(Trp)残基所处微环境的极性在减弱后保持基本不变, 酪氨酸残基所处微环境的极性在明显增强后稍有减弱, 苯丙氨酸残基所处微环境的极性略有增强. 结果表明, 当v由0增大到14时, SDS主要结合在BSA的Trp-213附近并逐渐形成聚集体, 从而诱导BSA由结构域ⅡA 开始逐渐展开. 此后, SDS呈正协同作用的特点与BSA 结合, v急剧增大. 当v约为302 时, SDS在BSA上的结合基本达到饱和, BSA的构象趋于稳定.     

二维配位聚合物[K2(5-nbdc)2Cd(Ⅱ)·imH·H2O]∞的合成和晶体结构(英)

The crystal structure of the title complex, [K₂(5-nbdc)₂Cd(Ⅱ)·imH·H₂O]_∞ (5-nbdc=5-nitro-1,3-benzenedicarbonate, imH=imidazole) has been determined by X-ray diffraction analysis. The crystal data are: tetragonal, space group P4₁, M_r=694.93 for CdC₁₉H₁₂N₄O₁₃K₂, a=1.018 6(10) nm, b=1.018 6(10) nm, c=2.436 7(5) nm; Z=4, V=2.528 2(6) nm³, F(000)=1 376, D_c=1.826 Mg·m^-3, μ=1.267 mm^-1. The title polymeric complex exhibits a two-dimensional framework, in which adjacent Cd(Ⅱ) ions are bridged by μ-O₄-5-nitro-1,3-benzenedicarbonate groups forming one-dimensional chains that are further linked by μ-O₃-5-nitro-1,3-benzenedicarbonate groups into two-dimensional anion rectangle sheets with large 32-membered rings. The strong π-π stacks of the benzene rings link these adjacent sheets into a three-dimensional van der Waals network. CCDC: 245527.     

Poly[3-(3,4-dihydroxyphenyl)glyceric acid] from Stems of <Emphasis Type="Italic">Symphytum asperum</Emphasis> and <Emphasis Type="Italic">S. caucasicum</Emphasis>

Two high-molecular-weight (>1000 kDa) water-soluble preparations were isolated from stems of Symphytum asperum and S. caucasicum. Their basic component was established as poly[hydroxy-1-carboxy-2-(3,4-dihydroxyphenyl)ethylene], analogous to that of high-molecular-weight (>1000 kDa) preparations from roots of these same plants, using IR and NMR spectral data. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 303–305, July–August, 2005. An erratum to this article is available at .     

Potentiometric Immunosensor Based on Immobilization of Hepatitis B Surface Antibody on Platinum Electrode Modified Silver Colloids and Polyvinyl Butyral as Matrixes

A highly sensitive immunosensor based on immobilization of hepatitis B surface antibody (HBsAb) on platinum electrode (Pt) modified silver colloids and polyvinyl butyral (PVB) as matrixes has been developed for potentiometric immunoanalysis to detect hepatitis B surface antigen (HBsAg) in this study. HBsAb molecules were immobilized successfully on nanometer‐sized silver colloid particles associated with polyvinyl butyral on a platinum electrode surface. The modification procedure was electrochemically monitored by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The HBsAb‐silver‐PVB‐modified electrode exhibited direct electrochemical behavior toward HBsAg. The factors influencing the performance of the resulting immunosensor were studied in detail. More than 94.7% of the results of human serum samples obtained by this method were in agreement with those obtained by enzyme‐linked immunosorbent assays (ELISAs). The resulting immunosensor exhibited a sigmoid curve with log HBsAg concentration, high sensitivity (39.8 mV/decade), wide linear range from 16.0 to 800 ng mL^?1 with a detection limit of 3.6 ng mL^?1, fast potentiometric response (<3 min) and long‐term stability (>4 months). The response mechanism of the immunosensors was also studied with AC impedance techniques.     

Arjunolic acid derivative glycoside from the stems of <Emphasis Type="Italic">Hedera colchica</Emphasis>

Five triterpenoid saponins were isolated from the stems of Hedera colchica K. Koch, Araliaceae. Two of them are new natural substances. HCSt-A (1): 3-O--D-arabinopyranoside; 28-O--L-rhamnopyranosyl-(1 4)-O--D-glucopyranosyl-(16)-O--D-glucopyranosyl-arjunolic acid. HCSt-B (2): 3-O--D-xylopyranoside; 28-O--L-rhamnopyranosyl-(14)-O--D-glucopyranosyl-(16)-O--D-glucopyranosyl-hederagenin. The derivative of arjunolic acid is described for the first time in Araliaceae family. The chemical structures of isolated compounds were established on the base of chemical and 1D and 2D NMR experiments.Published in Khimiya Prirodnykh Soedinenii, No. 6, pp. 461–463, November–December, 2004.This revised version was published online in April 2005 with a corrected cover date.     

低分子量聚乙烯双单体非均相共接枝

在非均相体系中采用甲苯－水共沸条件下由自由基引发剂引发，低分子量的聚乙烯与丙烯酸和甲基丙烯酸甲酯进行双单体共接枝反应，从而对非极性聚乙烯进行化学改性，探索一条新型聚乙烯接枝改性的途径，考察了反应温度、时间、物料比、引发剂用量等诸多因素对接枝效果的影响。