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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Antioxidant Properties of Phenolic Compounds: H-Atom versus Electron Transfer Mechanism
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Antioxidant Properties of Phenolic Compounds: H-Atom versus Electron Transfer Mechanism

机译:酚类化合物的抗氧化特性:H原子与电子转移机理

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Density functional theory (DFT) calculations were performed to evaluate the antioxidant activity of molecules commonly present in many Mediterranean foods. A series of interesting systems, including tyrosol, hydroxytyrosol, gallic, and caffeic acids, belonging to the family of phenols, resveratrol of the stilbenes family, epicatechin, kaempferol, and cianidin as examples of flavonoids and, at last, a simplified model of -tocopherol (6-hydroxy-2,2,5,7,8-pentamethylchroman (HPMC)) were studied. Conformational behavior was examined at the B3LYP/6-311++G(3df,2p) level of theory, in the gas phase and in two solvents with different polarity (water and benzene), with the aim to compute the bond dissociation enthalpy (BDE) for the O-H bonds and the adiabatic ionization potentials (IP). BDE and IP for these systems do not follow the same trends in gas and solution phases: the major differences with respect to vacuum are found as when water computations are performed. On the basis of the computed BDE and IP values, the most active systems able to transfer an H-atom seem to be -tocopherol followed by hydroxytyrosol, gallic acid, caffeic acid, and epicatechin. Instead, kaempferol and resveratrol appear to be the best candidates for an electron-transfer mechanism.
机译:进行密度泛函理论(DFT)计算以评估许多地中海食物中常见分子的抗氧化活性。一系列有趣的系统,包括苯酚家族的酪醇,羟基酪醇,没食子酸和咖啡酸,斯帝本家族的白藜芦醇,表儿茶素,山奈酚和cianidin作为类黄酮的例子,最后是-的简化模型研究了生育酚(6-羟基-2,2,5,7,8-五甲基苯并二氢吡喃(HPMC))。在B3LYP / 6-311 ++ G(3df,2p)理论水平下,在气相和两种极性不同的溶剂(水和苯)中检查了构象行为,目的是计算键解离焓( BDE)表示OH键和绝热电离电位(IP)。这些系统的BDE和IP在气相和液相阶段没有遵循相同的趋势:在进行水计算时,发现真空方面的主要差异。根据计算的BDE和IP值,能够转移H原子的最活跃的系统似乎是-生育酚,其次是羟基酪醇,没食子酸,咖啡酸和表儿茶素。相反,山奈酚和白藜芦醇似乎是电子转移机理的最佳候选者。

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