Electrochemical and Mechanistic Study of Reactivities of α-, β-, γ-, and δ-Tocopherol toward Electrogenerated Superoxide in N,N-Dimethylformamide through Proton-Coupled Electron Transfer.
Electrochemical and Mechanistic Study of Reactivities of α-, β-, γ-, and δ-Tocopherol toward Electrogenerated Superoxide in N,N-Dimethylformamide through Proton-Coupled Electron Transfer.
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DOI：
10.3390/antiox11010009
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发表时间：
2021-12-22
期刊：
影响因子：
--
通讯作者：
Uno B
中科院分区：
文献类型：
--
作者：
Nakayama T;Honda R;Kuwata K;Usui S;Uno B
基于循环伏安法和现场电解质电子自旋共振谱（electrolytic electron spin resonance spectroscopy，ESR）研究了生育酚（tocopherols，TOH）及其相关化合物在N，N-二甲基甲酰胺（DMF）中对超氧阴离子自由基（O2·−）的清除作用.准可逆的分子氧/O2·−氧化还原反应被TOH的存在所改变，表明电生成的O2·−被α-，β-，γ-TOH通过质子耦合电子转移（PCET）清除，而不被δ-TOH清除。实验证实了α-、β-、γ-和δ-TOH对O2·−的反应性，其特征在于6-色原烷醇环上的甲基，其中甲基促进PCET机制。此外，使用一些相关化合物进行的比较分析表明，6-色原烷醇环中的对位氧原子是通过PCET成功将电子转移（ET）到O2·−所必需的。电化学和DFT结果表明，在脱水DMF的PCET机制涉及前面的质子转移（PT）形成一个过氧化氢自由基，然后由PCET（分子间ET-PT）。TOH对O2·−的清除沿着一个ET和两个PT的PCET机制有效进行。
Scavenging of superoxide radical anion (O2•−) by tocopherols (TOH) and related compounds was investigated on the basis of cyclic voltammetry and in situ electrolytic electron spin resonance spectrum in N,N-dimethylformamide (DMF) with the aid of density functional theory (DFT) calculations. Quasi-reversible dioxygen/O2•− redox was modified by the presence of TOH, suggesting that the electrogenerated O2•− was scavenged by α-, β-, γ-TOH through proton-coupled electron transfer (PCET), but not by δ-TOH. The reactivities of α-, β-, γ-, and δ-TOH toward O2•− characterized by the methyl group on the 6-chromanol ring was experimentally confirmed, where the methyl group promotes the PCET mechanism. Furthermore, comparative analyses using some related compounds suggested that the para-oxygen-atom in the 6-chromanol ring is required for a successful electron transfer (ET) to O2•− through the PCET. The electrochemical and DFT results in dehydrated DMF suggested that the PCET mechanism involves the preceding proton transfer (PT) forming a hydroperoxyl radical, followed by a PCET (intermolecular ET–PT). The O2•− scavenging by TOH proceeds efficiently along the PCET mechanism involving one ET and two PTs.
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影响因子：
18.3
作者：
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