共查询到19条相似文献,搜索用时 62 毫秒
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荧光法研究硒酶模型化合物消除.OH自由基的作用 总被引:5,自引:0,他引:5
利用Fenton反应产生的羟基自由基与苯甲酸生成具有荧光的羟化苯甲酸,用荧光法间接测定羟基自由基的含量.用荧光法研究新合成的5种硒酶模型化合物对羟基自由基的清除作用.结果表明,新合成的硒酶模型化合物对羟基自由基有良好的清除作用.该法具有简便、快速、灵敏等特点. 相似文献
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明日叶黄酮类化合物清除羟基自由基活性研究 总被引:1,自引:0,他引:1
为了研究明日叶黄酮类化合物对羟基自由基的清除作用,以明日叶(主要取叶片)为原料,用体积分数为65%乙醇提取明日叶总黄酮,测定其总黄酮含量.通过Fenton反应体系产生羟基自由基,利用明日叶提取液中的功能成分黄酮类化合物对羟基自由基的清除作用进行研究.结果表明:明日叶提取物总黄酮质量分数为10.18%,且黄酮类化合物对羟基自由基有较强清除效力,当提取物总黄酮浓度在0.1~1.0 mg/mL范围内,其与清除率呈正相关.明日叶中黄酮类化合物对羟基自由基有较强清除效力,作为天然抗氧化产品开发具有一定价值. 相似文献
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三种含硒环糊精的SeGPX活力及对HO·的清除作用 总被引:6,自引:3,他引:3
报道了3种硒代β-环糊精作为SeGPX模拟物的活力,并初步探讨了硒环糊精的结构与活力的关系。利用Fenton反应产生的羟基自由基与苯甲酸钠反应生成的具有荧光的羟基苯甲酸间接测定羟基自由基的含量。结果表明,3种含硒环糊精对HO·的生成均无明显的抑制作用。 相似文献
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硒化合物与脂质过氧自由基作用的研究 总被引:6,自引:0,他引:6
本文以卵磷脂、亚油酸和脂质体作为生物膜模型, 鼠红细胞膜作为生物膜实例, 通过ESR研究, 观察到包括RSe和RSeSeR在内的硒化合物在模拟的和真实的生物膜体系中对脂质过氧自由基的清除作用, 使得硒作为自由基清除剂的假说在体外模型体系实验中被初步证实, 提示占体内总硒量约2/3的非GSH-Px硒可能是通过直接清除过氧自由基而发挥其生理功能, 研究表明, 其清除作用是针对生物膜磷脂分子上的不饱和脂肪酸过氧自由基, 其作用部位处于膜磷脂双分子层中部疏水区(脂相)中, 在体外实验的清除效果上, 有机硒优于无机硒, 某些有机硒化合物表面出“奇偶规律"。CNDO/2计算表明, 硒化合物清除脂质过氧自由基可能是通过硒中心自由基而起作用的。 相似文献
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(E)-N-芳基-3-[2-(8-羟基喹啉基)-乙烯基]咔唑的合成、抗氧化活性及促进鼠骨髓间质干细胞增殖的研究 总被引:4,自引:0,他引:4
设计合成了3-[2-(8-羟基喹啉基)-乙烯基]-N-对甲苯基咔唑(8)和3-[2-(8-羟基喹啉基)-乙烯基]-N-对甲氧苯基咔唑(9)两个新的化合物, 用IR, MS, 1H NMR和元素分析确认其结构. 并利用DPPH8226;方法, 超氧阴离子自由基( )法, 羟基自由基HO8226;法和噻唑蓝比色法(MTT法)分别测定了目标产物的抗氧化活性和调控鼠骨髓间质干细胞(MSCs)的作用. 结果表明, 这两种化合物对DPPH8226;自由基、超氧阴离子自由基和羟基自由基具有较强的抗氧化活性, 化合物9在低浓度时对鼠骨髓间质干细胞增殖有很好的促进作用. 相似文献
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羟基作为醇类化合物的基本结构单元,广泛存在于药物、天然产物、农药以及精细化学品中.烷基自由基则是自由基化学领域最基础性的合成砌块.因此,将醇转化为烷基自由基,具有基础性的研究价值.通常醇类化合物可以通过Barton-McCombie反应,实现自由基形式的脱羟基化反应,得到烷基自由基.然而传统脱羟基化反应存在诸多缺陷.因此发展一种简洁高效的脱羟基化方法具有重要的现实意义.随着近年来有机化学的发展,自由基脱羟基化反应取得突破性进展.本综述节选其中一部分,着重介绍了草酸酯类化合物在自由基脱羟基化反应中的研究进展和设计原理,对比不同活化策略的反应机理,系统性地总结了邻苯二甲酰亚胺类型草酸酯、草酸单酯和草酸酯类化合物在自由基脱羟基化反应中的共性和个性,展望了自由基脱羟基化反应的未来和趋势. 相似文献
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Effect of Molecular Interactions on Electron‐Transfer and Antioxidant Activity of Bis(alkanol)selenides: A Radiation Chemical Study
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Pavitra V. Kumar Dr. Beena G. Singh Dr. Prasad P. Phadnis Dr. Vimal K. Jain Dr. K. Indira Priyadarsini 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(34):12189-12198
Understanding electron‐transfer processes is crucial for developing organoselenium compounds as antioxidants and anti‐inflammatory agents. To find new redox‐active selenium antioxidants, we have investigated one‐electron‐transfer reactions between hydroxyl (.OH) radical and three bis(alkanol)selenides (SeROH) of varying alkyl chain length, using nanosecond pulse radiolysis. .OH radical reacts with SeROH to form radical adduct, which is converted primarily into a dimer radical cation (>Se∴Se<)+ and α‐{bis(hydroxyl alkyl)}‐selenomethine radical along with a minor quantity of an intramolecularly stabilized radical cation. Some of these radicals have been subsequently converted to their corresponding selenoxide, and formaldehyde. Estimated yield of these products showed alkyl chain length dependency and correlated well with their antioxidant ability. Quantum chemical calculations suggested that compounds that formed more stable (>Se∴Se<)+, produced higher selenoxide and lower formaldehyde. Comparing these results with those for sulfur analogues confirmed for the first time the distinctive role of selenium in making such compounds better antioxidants. 相似文献
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Kinetic schemes of intramolecular oxidation were constructed for ten hybrid analogues of 10-dihydroartemisinin with heteroatom-containing substituents (N, F, Cl). All steps of the kinetic scheme were characterized by the enthalpy of the reaction. The activation energies and rate constants were calculated using the intersecting parabolas model. During intramolecular oxidation of the model compounds, free radicals are generated, and the key role belongs to hydroxyl radicals. The kinetic method was developed, which provides the possibility to differentiate the therapeutic effect of hybrid compounds induced by the hydroxyl radicals alone from that induced in addition by the presence of substituents. Some compounds showed therapeutic effect which exceeds the effect caused by generation of the hydroxyl radicals alone. Several compounds bear substituents, which decrease the action induced by generation of the hydroxyl radicals. Substituents were identified, which made additional contribution to the therapeutic effect of the substance, thus providing the complex action. 相似文献
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合成了3-氨基-7,8-二甲氧基香豆素及其衍生物共11个化合物,其中3个化合物(2b、2d、2e)为新型香豆素芳酰胺类化合物。 通过猝灭1,1-二苯基-2-三硝基苯肼(DPPH)、2,2'-联氮二(3-乙基苯并噻唑-6-磺酸)二铵盐阳离子自由基(ABTS+·)和羟自由基实验考察了所合成化合物的抗氧化活性,结果表明化合物2b对DPPH自由基、羟自由基的清除能力超出或接近对照品维生素C,而衍生物2a、2b和2c的抗氧化活性优于母体。 故酰化可提高3-氨基-7,8-二甲氧基香豆素的抗氧化性能,尤其是普遍提高了羟基自由基的清除能力。 相似文献
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Teodor Adrian Enache Ana-Maria Chiorcea-Paquim Orlando Fatibello-Filho Ana Maria Oliveira-Brett 《Electrochemistry communications》2009,11(7):1342-1345
The hydroxyl radicals electrochemically generated in situ on a boron-doped diamond (BDD) electrode have been investigated for the first time in different electrolyte media, over the whole pH range between 1 and 11. A more extensive characterisation of BDD electrochemical properties is very important to understand the reactivity of organic compounds towards electrochemical oxidation on the BDD electrode, which is related to their interaction with adsorbed hydroxyl radicals due to water oxidation on the electrode surface. An oxidation peak corresponding to the transfer of one electron and one proton was observed in pH <9 electrolytes, associated with the water discharge process and electrochemical generation of hydroxyl radicals, which can interact and enhance the electro-oxidation of organic compounds. In pH >9 electrolytes the electrochemical generation of hydroxyl radicals was not observed; ammonia buffer electrolyte gave a pH-independent peak corresponding to the ammonia oxidation reaction. Additionally, for most pH values studied, a few small peaks associated with the electrochemical interaction between non-diamond carbon species on the doped diamond electrode surface and the electrolyte were also seen, which suggests that the doped diamond is relatively unreactive, but not completely inert, and the electrogenerated hydroxyl radicals play a role as mediator in the oxidation of organics. 相似文献
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Oliveira SC Oliveira-Brett AM 《Langmuir : the ACS journal of surfaces and colloids》2012,28(10):4896-4901
In situ DNA oxidative damage by electrochemically generated hydroxyl free radicals has been directly demonstrated on a boron-doped diamond electrode. The DNA-electrochemical biosensor incorporates immobilized double-stranded DNA (dsDNA) as molecular recognition element on the electrode surface, and measures in situ specific binding processes with dsDNA, as it is a complementary tool for the study of bimolecular interaction mechanisms of compounds binding to DNA and enabling the screening and evaluation of the effect caused to DNA by radicals and health hazardous compounds. Oxidants, particularly reactive oxygen species (ROS), play an important role in dsDNA oxidative damage which is strongly related to mutagenesis, carcinogenesis, autoimmune inflammatory, and neurodegenerative diseases. The hydroxyl radical is considered the main contributing ROS to endogenous oxidation of cellular dsDNA causing double-stranded and single-stranded breaks, free bases, and 8-oxoguanine occurrence. The dsDNA-electrochemical biosensor was used to study the interaction between dsDNA immobilized on a boron-doped diamond electrode surface and in situ electrochemically generate hydroxyl radicals. Non-denaturing agarose gel-electrophoresis of the dsDNA films on the electrode surface after interaction with the electrochemically generated hydroxyl radicals clearly showed the occurrence of in situ dsDNA oxidative damage. The importance of the dsDNA-electrochemical biosensor in the evaluation of the dsDNA-hydroxyl radical interactions is clearly demonstrated. 相似文献
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ESR spectra have been recorded for a number of radicals generated in a flow cell by interaction of diallylmalonic acid, diallyl ether, diallylamine, and related compounds with amino, hydroxyl, and phenyl radicals in aqueous solution. The results indicate that the radicals initially formed by homolytic addition at one of the double bonds in the diolefins rapidly undergo cyclization to afford product radicals containing five-membered rings. 相似文献
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Electroreduction of benzo-1,2,3-dithiazolium salts and their selenium analogs in nonaqueous solution
V. Sh. Tsveniashvili M. V. Malashkhiya V. N. Gaprindashvili B. Kh. Strelets M. M. Gel'mont Yu. I. Akulin 《Chemistry of Heterocyclic Compounds》1985,21(2):181-184
The electroreduction of benzo-1,2,3-dithiazolium cations and their selenium analogs in aprotic solvents takes place in two steps. The first step is a reversible, one-electron transfer leading to the formation of stable radicals detected by EPR. As a result of further electroreduction, the radicals obtained combine with six electrons to form the corresponding o-aminothio(seleno)phenols. Analysis of the reduction potentials of the compounds studied shows that the substitution of a selenium atom for a sulfur in these cations, especially in the 2 position of the heterocycle, facilitates their electrochemical reduction. The electrochemical activity and the kinetics of nulceophilic substitution in the cations studied are compared.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 219–222, February, 1985. 相似文献
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Denisov E 《Organic & biomolecular chemistry》2011,9(11):4219-4225
The kinetic schemes of intramolecular reactions of five analogs of artemisinin were built. The method of intersecting parabolas was used for the calculation of activation energies and rate constants of each elementary step of these schemes. The competition between monomolecular and bimolecular free radicals was taken into account. It was evidenced that the intramolecular oxidation of these compounds proceeds as a cascade of consecutive free radical reactions with the formation of hydroperoxide groups. The latter decompose via reactions with the Fe(II) complexes generating free radicals. Among the radicals formed, the hydroxyl radical was proved to play the key role. A correlation between the yield of hydroxyl radicals n(OH) and antimalarial activity of compounds (IC(50)) was observed. The dependence of index IC(50) on n(OH) is linear in the logarithmic coordinates: ln[IC(50)(Artemisinin)/IC(50)(Compound)] = -14.10 + 3.85 ×n(OH). The proposed scheme explains and demonstrates a strong dependence of the antimalarial effectiveness of a drug on the chemical structure. 相似文献