The vast majority of previous studies dealing with antioxidant potency of (poly)phenols does not investigate the fate of phenoxyl radical obtained after single free radical scavenging. We investigated possible pathways of inactivation of ferulic acid phenoxyl radical (FAPR) using DFT method. Direct coupling with a set of 10 physiologically important free radicals, H-atom donation and dimerization were analysed by estimation of Gibbs free energy changes related to these processes. The former two processes are thermodynamically feasible to inactivate more dangerous free radicals such as hydroxyl, alkoxyl and carbon-centered radicals. Among dimerization reactions, the least energy demanding is formation of C-5-C-5 dimer of ferulic acid (FA), which has higher antiradical potency than FA itself. Obtained results reveal that FAPR, a priori considered as stable and unreactive, may contribute to the overall antioxidant activity of FA. This is a beneficial behavior, which makes FA a particularly valuable protector against oxidative stress. Hence, the contribution of phenoxyl radicals to the antioxidant activity of (poly)phenolic compounds should be taken into account, what has been scarcely considered until now.

中文翻译：

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阿魏酸苯氧基自由基的抗氧化能力

以前关于（多）酚的抗氧化效力的绝大多数研究都没有研究单次自由基清除后获得的苯氧基自由基的命运。我们使用 DFT 方法研究了阿魏酸苯氧基自由基 (FAPR) 失活的可能途径。通过估计与这些过程相关的吉布斯自由能变化，分析了与一组 10 个生理上重要的自由基、H 原子捐赠和二聚化的直接偶联。前两个过程在热力学上是可行的，可以灭活更危险的自由基，如羟基、烷氧基和碳中心自由基。在二聚反应中，能量需求最低的是形成阿魏酸 (FA) 的 C-5-C-5 二聚体，其具有比 FA 本身更高的抗自由基效力。获得的结果表明，FAPR，先验被认为是稳定和无反应的，可能有助于 FA 的整体抗氧化活性。这是一种有益的行为，使 FA 成为一种特别有价值的抗氧化应激保护剂。因此，应考虑苯氧基自由基对（多）酚类化合物的抗氧化活性的贡献，而这点迄今为止几乎没有被考虑过。