Saffari Yasi, Sadrzadeh S M Hossein
Department of Laboratory Medicine, University of Washington, Harborview Medical Center, 325 9th Avenue, Seattle, WA 98104, USA.
Life Sci. 2004 Feb 6;74(12):1513-8. doi: 10.1016/j.lfs.2003.08.019.
Green tea polyphenols like epigallocatechin gallate (EGCG) have been proposed as a cancer chemopreventative. Several studies have shown that EGCG can act as an antioxidant by trapping proxyl radicals and inhibiting lipid peroxidation. The main propose of this study is to investigate the antioxidant capacity of EGCG using erythrocyte membrane-bound ATPases as a model. The effects of EGCG on t-butylhydroperoxide-induced lipid peroxidation and the activity of membrane-bound ATPases in human erythrocyte membranes were studied. The extent of oxidative damage in membranes was assessed by measuring lipid peroxidation, (TBARS, thiobarbituric acid reactive substances formation) and the activity of ATPases (Na(+)/K(+), Ca(2+), and CaM-activated Ca(2+) pump ATPases). EGCG blocked t-BHP induced lipid peroxidation in erythrocyte membranes, significantly (0.45 +/- 0.02 vs 0.20 +/- 0.01; t-BHP vs t-BHP + EGCG respectively, microm/L TBARS) (p < 0.05). EGCG also protected ATPases against t-BHP induced damage; for Na/K ATPase (2.4 +/- 0.2 vs 1.6 +/- 0.1 vs 2.44 +/- 0.2, nmol Pi/min/mg protein, control vs t-BHP vs t-BHP and EGCG respectively), for Ca ATPase (5.8 +/- 0.4 vs 3.9 +/- 0.3 vs 5.6 +/- 0.34, nmol Pi/min/mg protein, control vs t-BHP vs t-BHP and EGCG respectively) and for CaM-Ca ATPase (14.7 +/- 0.7 vs 7.3 +/- 0.4 vs 11.6 +/- 0.55, nmol Pi/min/mg protein, control vs t-BHP vs t-BHP and EGCG respectively) (p < 0.05). In conclusion our results indicate that EGCG is a powerful antioxidant that is capable protecting erythrocyte membrane-bound ATPases against oxidative stress.
绿茶多酚如表没食子儿茶素没食子酸酯（EGCG）已被提议作为一种癌症化学预防剂。多项研究表明，EGCG可通过捕获过氧自由基和抑制脂质过氧化作用来充当抗氧化剂。本研究的主要目的是以红细胞膜结合ATP酶为模型，研究EGCG的抗氧化能力。研究了EGCG对叔丁基过氧化氢诱导的脂质过氧化作用以及人红细胞膜中膜结合ATP酶活性的影响。通过测量脂质过氧化（TBARS，硫代巴比妥酸反应性物质形成）和ATP酶（Na(+)/K(+)、Ca(2+)以及钙调蛋白激活的Ca(2+)泵ATP酶）的活性来评估膜中的氧化损伤程度。EGCG可阻断叔丁基过氧化氢诱导的红细胞膜脂质过氧化，差异显著（分别为0.45±0.02与0.20±0.01；叔丁基过氧化氢组与叔丁基过氧化氢+EGCG组，微摩尔/升TBARS）（p<0.05）。EGCG还可保护ATP酶免受叔丁基过氧化氢诱导的损伤；对于钠钾ATP酶（分别为2.4±0.2、1.6±0.1、2.44±0.2，纳摩尔无机磷/分钟/毫克蛋白质，对照组、叔丁基过氧化氢组、叔丁基过氧化氢+EGCG组），对于钙ATP酶（分别为5.8±0.4、3.9±0.3、5.6±0.34，纳摩尔无机磷/分钟/毫克蛋白质，对照组、叔丁基过氧化氢组、叔丁基过氧化氢+EGCG组）以及对于钙调蛋白-钙ATP酶（分别为14.7±0.7、7.3±0.4、11.6±0.55，纳摩尔无机磷/分钟/毫克蛋白质，对照组、叔丁基过氧化氢组、叔丁基过氧化氢+EGCG组）（p<0.05）。总之，我们的结果表明，EGCG是一种强大的抗氧化剂，能够保护红细胞膜结合ATP酶免受氧化应激的影响。
