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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Scavenging Mechanism of Curcumin Toward the Hydroxyl Radical: A Theoretical Study of Reactions Producing Ferulic Acid and Vanillin
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Scavenging Mechanism of Curcumin Toward the Hydroxyl Radical: A Theoretical Study of Reactions Producing Ferulic Acid and Vanillin

机译：姜黄素清除羟自由基的机理：阿魏酸与香兰素反应的理论研究

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摘要

Curcumin is known to be an antioxidant, as it can scavenge free radicals from biological media. A sequence of H-abstraction and addition reactions involving up to eight OH radicals and curcumin or its degradation products leading to the formation of two other antioxidants, namely, ferulic acid and vanillin, was studied. Single electron transfer from curcumin to an OH radical was also studied. All relevant extrema on the potential energy surfaces were located by optimizing geometries of the reactant and product complexes, as well as those of the transition states, at the BHandHLYP/6-31G(d,p) level of density functional theory in the gas phase. Single-point energy calculations were also performed in the gas phase at the BHandHLYP/aug-cc-pVDZ and B3LYP/aug-cc-pVDZ levels of theory. Solvent effects in aqueous media were treated by performing single-point energy calculations at all of the above-mentioned levels of theory employing the polarizable continuum model and the geometries optimized at the BHandHLYP/6-31G(d,p) level in the gas phase. A few reaction steps were also studied by geometry optimization in aqueous media, and the thus-obtained Gibbs free energy barriers were similar to those obtained by corresponding single-point energy calculations. Our calculations show that the hydrogen atom of the OH group attached to the phenol moiety of curcumin would be most efficiently abstracted by an OH radical, in agreement with experimental observations. Further, our study shows that OH addition would be most favored at the C10 site of the heptadiene chain. It was found that curcumin can serve as an effective antioxidant.
机译：姜黄素已知是一种抗氧化剂，因为它可以清除生物介质中的自由基。研究了一系列涉及多达8个OH自由基和姜黄素或其降解产物的H吸收和加成反应的序列，这些反应导致形成另外两种抗氧化剂，即阿魏酸和香草醛。还研究了姜黄素到OH自由基的单电子转移。通过优化反应物和产物配合物的几何形状以及过渡态的几何形状，在气相的密度泛函理论的BHandHLYP / 6-31G（d，p）级别上定位了势能表面上的所有相关极值。在气相中也以理论上的BHandHLYP / aug-cc-pVDZ和B3LYP / aug-cc-pVDZ水平进行了单点能量计算。通过使用可极化连续介质模型和在气相中BHandHLYP / 6-31G（d，p）水平优化的几何形状，在上述所有理论水平上进行单点能量计算，处理了水介质中的溶剂效应。还通过在水性介质中进行几何优化对一些反应步骤进行了研究，因此获得的吉布斯自由能垒与通过相应的单点能量计算获得的自由能垒相似。我们的计算表明，与实验观察结果一致，与姜黄素的酚部分相连的OH基团的氢原子将被OH基团最有效地提取。此外，我们的研究表明，在庚二烯链的C10位上，OH加成最受青睐。发现姜黄素可以作为有效的抗氧化剂。

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