On‐line HPLC method for screening of antioxidants against superoxide anion radical from complex mixtures

A practical approach for rapidly screening antioxidants against superoxide anion radicals from complex mixtures was developed based on the quantitative difference in active compounds before and after their reaction. To test the effectiveness of the approach, seven flavonoids with antioxidative properties were investigated both individually and in a mixture. Using the approach, antioxidants could be rapidly separated and screened with a ranked order of activities in the meantime. The radical scavenging activities were in the following order: quercetin > kaempferol > fisetin > puerarin > luteolin > rutin > baicalein. The order of activity was conducted by comparing the scavenging ratio of the antioxidant, which was completely consistent with the results obtained from the traditional electronic spin resonance. Then, the method was successfully applied to black tea extracts. This approach is fast and convenient for screening, isolating, and analyzing potential antioxidants from a mixture with good quantitative and reproducible ability.     

Sonogel-carbon electrode based on hemin for detection of superoxide

The Sonogel electrode was immersed in hemin solution to obtain the hemin-Sonogel-modified electrode by cyclic voltammetry (CV). It was applied to detect superoxide radicals produced by xanthine oxidase catalyzed hypoxanthine oxidation. The characterization of hemin-Sonogel was modified by impedance and CV.     

Crystal Structure and Superoxide Dismutase Activity of [Cu(ethylenediamine)<Subscript>2</Subscript>Cl][PF<Subscript>6</Subscript>]

Summary. The preparation, spectroscopic properties, and crystal structure of chlorobis(ethylenediamine)copper(II) hexafluorophosphate [Cu(en)₂Cl][PF₆], (en=ethylendiamine) are reported. The complex crystallizes in the monoclinic system, space group P2₁/c, with cell constants a=6.1488(9) Å, b=12.696(2) Å, c=17.7424(17) Å, =97.265(12)°, and Z=4. The copper(II) ion is coordinated to two bidentate en molecules, to one chlorine ion, and to a more distant fluorine atom of the PF₆ group, leaving the copper ion in a distorted octahedral coordination geometry. The superoxide dismutase mimetic activity of the complex was investigated using the indirect xanthine-xanthine oxidase- nitroblue tetrazolium method and compared to that of the native enzyme.     

采样极谱法测定SOD模型化合物催化超氧离子歧化反应速率常数

用采样极谱法研究了非质子溶剂中SOD模型化合物催化O₂^-的歧化反应,用简化的函数关系代替动力学微分方程的准确解.通过测定极限催化电流与极限扩散电流比随SOD模型化学物浓度及滴汞电极滴下时间的变化,确定催化O₂^-歧化反应速率常数K₁.     

Nucleophilic Substitution of Halogenonitrobenzenes by Electrogenerated O2- on Carbon Gas-diffusion-electrode

Introduction The electrochemical reduction of O_2 was investigated widely during the past two decades. O_2~- can react with various organic compounds. O_2~- as a new synthesis reagent has been being explored.     

超氧化物歧化酶在以促进剂修饰的金电极上的电化学行为

应用循环伏安法探索了超氧化物歧化酶在Ｌ－半胱氨酸、组氨酸和精氨酸等氨基酸修饰的金丝电极上的电化学行为。实验结果表明,Ｌ－半胱氨酸是超氧化物歧化酶的有效促进剂。组氨酸和精氨酸则对超氧化物歧化酶氧化过程池不同程度的促进作用。此外,还讨论了４,４－二硫基联吡啶对超氧化物歧化酶电子传递过程的促进作用。     

金电极上电子传递促进剂作用的EQCM研究

本文比较了L_半胱氨酸、组氨酸和精氨酸等三种氨基酸在石英晶体微天平金电极上的吸附行为 .重点考察了超氧化物歧化酶在L_半胱氨酸存在的混合溶液中以及事先经L_半胱氨酸修饰的金晶振电极上的循环伏安曲线和频率响应曲线 .实验结果表明 ,超氧化物歧化酶在L_半胱氨酸修饰的金晶振电极上的电子传递过程是一个准可逆过程 ,它同时对应于一个可逆的吸脱附过程 .初步讨论了L_半胱氨酸对超氧化物歧化酶电子传递过程的促进机制 .     

新型兼具GPX,SOD, CAT活性的水杨醛Schiff碱衍生物的合成

以5-磺基水杨醛为母体, 经氯甲基化和硒化反应引入催化基团-SeH, 此化合物经空气氧化、Schiff碱反应以及锰螯合反应, 最终得到一种新型的水杨醛Schiff碱类谷胱甘肽过氧化物酶(GPX)模拟物. 测定了该模拟物的红外光谱、核磁共振谱、质谱和抗氧化能力. 此模拟物同时兼具超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性, 水溶性好, 保护线粒体免遭氧化损伤能力强, 具有作为药物前体的潜力.     

Purification and Characterization of Superoxide Dismutase （SOD） from Camellia Pollen

A superoxide dismutase（ SOD ） was purified to homogeneity from fresh camellia pollen by means of ammonium sulfate precipitation and column chromatography with DEAE-cellulose（ DE52 ）, Sephadex G-100 and phenyl sepharose^TM 6 Fast Flow columns. Its specific activity could reach to 4034 U/mg protein and it was determined to be Cu/ Zn-SOD according to its different sensitivities to different inhibitors. The molecular weight of the SOD and its subunit were 69500 and 34700, respectively, based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis （SDS- PAGE）, which implicates that the SOD in camellia pollen is a dimmer composed of two identical subunits. The isoelectric point of the enzyme was determined to be 4. 1 by isoelectric focusing electrophoresis and the N-terminal amino acid was identified to be Gly by the DNS-Cl method. Its α-Helix was also calculated to be approximately 21.8% according to the circular dichroism（CD） spectra.     

电化学原位拉曼光谱技术对金电极表面生物分子吸附行为研究

报道腺嘌呤在裸金电极及其修饰的金电极上的电化学原位拉曼光谱图 ,着重分析了不同电位下腺嘌呤和超氧化物歧化酶在金电极上的吸附及其相互作用 ,初步讨论了腺嘌呤对促进超氧化物歧化酶电子传递过程的作用机制 .