Studies on protective mechanisms of four components of green tea polyphenols against lipid peroxidation in synaptosomes
Studies on protective mechanisms of four components of green tea polyphenols against lipid peroxidation in synaptosomes
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DOI：
10.1016/s0005-2760(96)00122-1
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发表时间：
1996-12-13
期刊：
影响因子：
--
通讯作者：
Xin, WJ
中科院分区：
文献类型：
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作者：
Guo, QN;Zhao, BL;Xin, WJ
“绿茶多酚”（GTP）四种成分——（-）-表没食子儿茶素没食子酸酯、EGCG的保护作用比较； (-)-表儿茶素没食子酸酯，心电图； (-)表没食子儿茶素，EGC； (-)表儿茶素、EC对铁诱导的突触体脂质过氧化的抑制作用表明：(1)这些化合物对脂质过氧化引起的TBA反应物质的抑制作用按EGCG>ECG>EGC>EC的顺序降低； (2)这些化合物对脂质过氧化产生的脂质自由基的清除作用可分为：ECG>EGCG>EC>EGC。此外，我们研究了这些化合物的铁螯合活性和自由基清除活性，作为它们针对突触体中脂质过氧化的保护机制。至于铁螯合活性，EGC、EGCG、ECG或EC与铁(III)的比例分别为3:2、2:1、2:1和3:1。在 H2O2 系统的光解作用中研究了这些化合物的羟基自由基 (HO.) 清除活性。结果发现，它们清除羟自由基的能力按ECG>EC>EGCG的顺序下降，远大于EGC。还发现它们可以清除卵磷脂/脂氧化酶系统中的脂质自由基，其清除活性分级如下：ECG>EGCG远大于EGC>EC。此外，我们发现它们的抗氧化活性位置彼此不同，并且这些化合物在NaOH溶液中产生的半醌自由基的稳定性按照EGCG>ECG的顺序降低，远大于EC。结果表明，这些化合物保护突触体免受Fe2+/Fe3+引发的脂质过氧化损伤的能力不仅取决于它们的铁螯合活性和自由基清除活性，还取决于它们的半醌自由基的稳定性。
The comparison of the protective effects of four components of 'green tea polyphenols' (GTP) - (-)-epigallocatechin gallate, EGCG; (-)-epicatechin gallate, ECG; (-)epigallocatechin, EGC; and(-)epicatechin, EC - against iron-induced lipid peroxidation in synaptosomes showed that: (1) the inhibitory effects of those compounds on TBA reactive materials from lipid peroxidation decreased in the order of EGCG > ECG > EGC > EC; (2) the scavenging effects of those compounds on lipid free radicals produced by lipid peroxidation could be classified as follows: ECG > EGCG > EC > EGC. Furthermore, we investigated the iron-chelating activity and the free radical scavenging activity of those compounds as their protective mechanisms against lipid peroxidation in synaptosomes. As for the iron-chelating activity, the ratio of EGC, EGCG, ECG or EC to iron(III) was 3:2, 2:1, 2:1 and 3:1, respectively. The hydroxyl radical (HO.) scavenging activity of those compounds was investigated in a photolysis of the H2O2 system. It was found that their ability to scavenge hydroxyl radicals decreased in the order of ECG > EC > EGCG much greater than EGC. It was also found that they could scavenge lipid free radicals in the lecithin/lipoxidase system and their scavenging activity was classified as follows: ECG > EGCG much greater than EGC > EC. Moreover, we found that their antioxidant active positions were different from each other and the stability of the semiquinone free radicals produced by those compounds in NaOH solution decreased in the order of EGCG > ECG much greater than EC. The results indicated that the ability of those compounds to protect synaptosomes from the damage of lipid peroxidation initiated by Fe2+/Fe3+ was dependent not only on their iron-chelating activity and free-radical scavenging activity, but also on the stability of their semiquinone free radicals.