Kinetics of iron oxidation upon polyphenol binding
Kinetics of iron oxidation upon polyphenol binding
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DOI：
10.1039/c0dt00752h
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发表时间：
2010-01-01
影响因子：
4
通讯作者：
Brumaghim, Julia L.
中科院分区：
文献类型：
--
作者：
Perron, Nathan R.;Wang, Hsiao C.;Brumaghim, Julia L.
多酚预防铁介导的DNA损伤主要是通过铁结合发生的。一旦结合，铁(2+)-多酚复合物中的铁在O(2)存在下自动氧化为铁（3+）。为了确定铁(2+)-多酚自氧化速率与多酚抗氧化能力之间的关系，采用紫外-可见分光光度法在pH = 6.0的条件下进行了动力学研究。铁多酚复合物对表没食子儿茶素没食子酸酯（EGCG）、甲基-3,4,5-三羟基苯甲酸酯（MEGA）、没食子酸（GA）、表儿茶素（EC）和甲基-3,4-二羟基苯甲酸酯（MEPCA）的初始氧化速率在0.14-6.7 min（-1）之间。与儿茶酚类似物相比，含有没食子酚基团的多酚具有更快的铁氧化速率，这表明更强的铁结合导致更快的铁氧化。研究了多酚、Fe（2+）和O(2)的浓度变化对MEGA和MEPCA中Fe(2+)-多酚自氧化反应的影响。对于这些类似的铁（2+）的没食子酸盐和儿茶酚酸盐配合物，铁的氧化反应在铁（2+）、多酚和O(2)中是一级的，但没食子酸盐配合物在低铁（2+）浓度下表现出饱和行为。因此，含胆酚的多酚促进铁氧化的速度明显快于类似的含儿茶酚的化合物，铁氧化速率也与多酚抑制含有单个铁结合片段的多酚化合物的DNA损伤密切相关。
Polyphenol prevention of iron-mediated DNA damage occurs primarily through iron binding. Once bound, iron in the Fe(2+)-polyphenol complex autooxidizes to Fe(3+) in the presence of O(2). To determine the correlation between the rate of Fe(2+)-polyphenol autooxidation and polyphenol antioxidant ability, kinetic studies at pH = 6.0 in the presence of oxygen were performed using UV-vis spectrophotometry. Initial rates of iron-polyphenol complex oxidation for epigallocatechin gallate (EGCG), methyl-3,4,5-trihydroxybenzoate (MEGA), gallic acid (GA), epicatechin (EC), and methyl-3,4-dihydroxybenzoate (MEPCA) were in the range of 0.14-6.7 min(-1). Polyphenols with gallol groups have faster rates of iron oxidation than their catechol analogs, suggesting that stronger iron binding results in faster iron oxidation. Concentrations of polyphenol, Fe(2+), and O(2) were varied to investigate the dependence of the Fe(2+)-polyphenol autooxidation on these reactants for MEGA and MEPCA. For these analogous gallate and catecholate complexes of Fe(2+), iron oxidation reactions were first order in Fe(2+), polyphenol, and O(2), but gallate complexes show saturation behavior at much lower Fe(2+) concentrations. Thus, gallol-containing polyphenols promote iron oxidation at a significantly faster rate than analogous catechol-containing compounds, and iron oxidation rate also correlates strongly with polyphenol inhibition of DNA damage for polyphenol compounds with a single iron-binding moiety.