Importance of Proton-Coupled Electron Transfer from Natural Phenolic Compounds in Superoxide Scavenging
Importance of Proton-Coupled Electron Transfer from Natural Phenolic Compounds in Superoxide Scavenging
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DOI：
10.1248/cpb.c15-00447
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发表时间：
2015-12-01
影响因子：
1.7
通讯作者：
Uno, Bunji
中科院分区：
文献类型：
--
作者：
Nakayama, Tatsushi;Uno, Bunji
基于电化学和电子自旋共振（ESR）光谱测量，借助密度泛函理论（DFT）计算，研究了天然酚类化合物（+）-儿茶素（Cat）、槲皮素（Que）、芦丁和α-生育酚（α-TOH）清除超氧阴离子O-2（中心点-）的反应.的O-2/O-2（中心点-）氧化还原对的可逆性显着影响的酚类化合物的存在。儿茶酚部分的猫，Que，和芦丁在协同质子耦合电子转移（PCET）HO 2中心点起着至关重要的作用。由O-2（中心点-）衍生得到H2 O2和相应的邻苯醌自由基阴离子。另一方面，α-TOH的存在导致顺序的电子和质子转移到H-2（中心点），得到H2 O2和α-生育酚自由基。这些电子转移的酚类化合物的存在下，推断从ESR光谱测量。DFT计算结果表明，天然酚类化合物清除O-2（中心点-）的反应符合一步协同PCET或顺序PCET机理。
The superoxide O-2(center dot-) scavenging reaction of (+)-catechin (Cat), quercetin (Que), rutin, and alpha-tocopherol (alpha-TOH) as natural phenolic compounds is investigated on the basis of electrochemical and ESR spectral measurements with the aid of density functional theory (DFT) calculations. Reversibility of the O-2/O-2(center dot-) redox couple is significantly affected by the presence of the phenolic compounds. The catechol moiety of Cat, Que, and rutin plays an essential role in concerted proton-coupled electron transfer (PCET) to HO2 center dot. derived from O-2(center dot-) to give H2O2 and the corresponding o-benzoquinone radical anions. On the other hand, the presence of alpha-TOH causes sequential electron and proton transfers to H-2(center dot) to give H2O2 and the alpha-tocopheroxyl radical. These electron transfers in the presence of the phenolic compounds are inferred from the ESR spectral measurements. The DFT calculation results suggest that the O-2(center dot-) scavenging reaction of the natural phenolic compounds proceeds efficiently with the one-step concerted PCET or sequential PCET mechanism.