The mechanism of reaction of ebselen with superoxide in aprotic solvents as examined by cyclic voltammetry and ESR
The mechanism of reaction of ebselen with superoxide in aprotic solvents as examined by cyclic voltammetry and ESR
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DOI：
10.1248/cpb.49.541
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发表时间：
2001-05-01
影响因子：
1.7
通讯作者：
Kitaoka, H
中科院分区：
文献类型：
--
作者：
Araki, T;Kitaoka, H
用ESR和电化学技术研究了ebselen与超氧化物的氧化还原反应机理。用循环伏安法和ESR自旋捕获法跟踪了在非质子溶剂中与超氧化物的反应。在循环伏安图中，ebselen的加入明显降低了超氧化物的氧化电流，ebselen以剂量依赖的方式降低了5，5-二甲基-1-吡咯啉N-氧化物(DMPO)-超氧化物的ESR信号强度。快速混合连续流动电子自旋共振证实了该氧化还原反应中氨基自由基的形成。亚硒酸型和亚硒酸型是亚硒与超氧化物反应的最终产物。该氧化还原反应的机理如下：第一，ebselen与超氧化物反应，转化为ebselen阴离子自由基；第二，ebselen阴离子自由基与超氧化物反应，转化为氨基自由基。氨基发生抽氢反应，得到亚硒酸盐和亚硒酸盐两种形式。
The mechanism of the redox reaction of ebselen with superoxide was investigated using both ESR and electrochemical techniques. The reaction with superoxide in aprotic solvents was followed by means of cyclic voltammetry and ESR spin-trapping. A decrease in the oxidation current due to superoxide as a result of the addition of ebselen was clearly observed in the cyclic voltammograms, Ebselen reduced the ESR signal intensity of 5,5-dimethyl-1-pyrroline N-oxide (DMPO)-superoxide in a dose-dependent manner. The formation of an amidyl radical in this redox reaction was confirmed by rapid mixing continuous-flow ESR. The selenonate form and the seleninate form of ebselen were identified as the final products of the reaction of ebselen with superoxide. The following mechanism for this redox reaction can be proposed: First, ebselen reacts with superoxide and is converted to an ebselen anion radical; second, the ebselen anion radical reacts with superoxide and is converted to the amidyl radical. Hydrogen abstraction by the amidyl radical occurs and gives both a seleninate form and a selenonate form.