Thiol-Dependent Reduction of the Triester and Triamide Derivatives of Finland Trityl Radical Triggers O-2-Dependent Superoxide Production
Thiol-Dependent Reduction of the Triester and Triamide Derivatives of Finland Trityl Radical Triggers O-2-Dependent Superoxide Production
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芬兰三酯和三酰胺衍生物的硫醇依赖性还原三苯甲基自由基触发 O-2 依赖性超氧化物产生
DOI：
10.1021/acs.chemrestox.7b00086
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发表时间：
2017
影响因子：
4.1
通讯作者：
Liu Yangping
中科院分区：
文献类型：
--
作者：
Tan Xiaoli;Chen Li;Song Yuguang;Rockenbauer Antal;Villamena Frederick A.;Zweier Jay L.;Liu Yangping
四硫代三苯甲基自由基作为磁共振探针在生物医学领域有着广泛的应用。三苯甲基自由基及其衍生物通常对生物还原剂如谷胱甘肽（GSH）和抗坏血酸盐稳定。我们证明，芬兰三苯甲基自由基的三酯（ET-03）和三酰胺（AT-03）衍生物表现出独特的还原巯基，如GSH和半胱氨酸（Cys），以产生相应的三苯甲基碳负离子的EPR信号的损失和出现的特征紫外-可见吸收在644 nm下在厌氧条件下证明。三苯甲基碳负离子可以通过空气中的氧气（O2）快速转化回原始的三苯甲基自由基，从而使三苯甲基衍生物和生物硫醇之间的反应在有氧条件下不可检测。EPR自旋捕获表明，三苯甲基碳负离子还原O2的产物为超氧自由基（O2·-）。动力学研究表明，反应速率常数（k）取决于三苯甲基自由基和巯基的类型，其顺序为kET-03/Cys（0.336 M-1 s-1）>kET-03/GSH（0.070 M-1 s-1）>kAT-03/Cys（0.032 M-1 s-1）>kAT-03/GSH（0.027 M-1 s-1）。三苯甲基自由基与硫醇的反应活性与三苯甲基自由基的对位取代基以及硫醇的pKa密切相关，并进一步反映在O2·-的产生速率和O2和硫醇的消耗速率上。这一新反应代表了三苯甲基衍生物的一种新的代谢过程，在新的三苯甲基自由基探针的设计和应用中应予以考虑。
Tetrathiatriaylmethyl (trityl) radicals have found wide biomedical applications as magnetic resonance probes. Trityl radicals and their derivatives are generally stable toward biological reducing agents such as glutathione (GSH) and ascorbate. We demonstrate that the triester (ET-03) and triamide (AT-03) derivatives of the Finland trityl radical exhibit unique reduction by thiols such as GSH and cysteine (Cys) to generate the corresponding trityl carbanions as evidenced by the loss of EPR signal and appearance of characteristic UV–vis absorbance at 644 nm under anaerobic conditions. The trityl carbanions can be quickly converted back to the original trityl radicals by oxygen (O2) in air, thus rendering the reaction between the trityl derivative and biothiol undetectable under aerobic conditions. The reduction product of O2by the trityl carbanions was shown to be superoxide radical (O2•–) by EPR spin-trapping. Kinetic studies showed that the reaction rate constants (k) depend on the types of both trityl radicals and thiols with the order ofkET-03/Cys(0.336 M–1s–1) >kET-03/GSH(0.070 M–1s–1) >kAT-03/Cys(0.032 M–1s–1) >kAT-03/GSH(0.027 M–1s–1). The reactivity of trityl radicals with thiols is closely related to the para-substituents of trityl radicals as well as the pKaof the thiols and is further reflected by the rate of O2•–production and consumptions of O2and thiols. This novel reaction represents a new metabolic process of trityl derivatives and should be considered in the design and application of new trityl radical probes.