Quantitative Structure–Activity Analyses of Novel Hydroxyphenylurea Derivatives as Antioxidants
作者:Kazuya Nakao、Ryo Shimizu、Hitoshi Kubota、Mikiko Yasuhara、Yoshimasa Hashimura、Toshikazu Suzuki、Toshio Fujita、Hiroshi Ohmizu
DOI:10.1016/s0968-0896(98)00039-x
日期:1998.6
importance in governing the inhibitory potency. An increase in the electron donating property of substituents toward the phenolic hydroxyl group enhanced the antioxidative activity by the stabilization of an electron-deficient radical-type transition state. The steric shielding by ortho-substituents stabilized the phenoxy radicals formed following the transition state. Derivatives having the carboxyl group
合成了一系列取代的羟基苯基脲,其化学结构是基于天然抗氧化剂,维生素E(α-生育酚)和尿酸的结构设计的。它们显示出对脂质过氧化的高抑制活性。为了深入了解抑制反应的机理,我们定量分析了它们的构效关系。取代基对酚羟基的电子和空间效应显示出对控制抑制效力的重要性。取代基对酚羟基的给电子性的增加通过稳定电子缺陷的自由基型过渡态而增强了抗氧化活性。邻位取代基的空间屏蔽作用稳定了过渡态后形成的苯氧基。推测具有羧基的衍生物仅是弱活性的,这是因为酚羟基与羧酸根阴离子的分子间离子-偶极相互作用会延迟过渡态的形成。