KMID : 0603519990040010009
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Journal of Korean Association of Cancer Prevention 1999 Volume.4 No. 1 p.9 ~ p.16
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Cytoprotective Mechanisms of Green Tea Polyphenols in Cultured Liver Cells
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Kye In-Sook
Jeon Young-Soo Soung Do-Yu Lee Sook-Hee Kim Jong Yokozawa Takako Chung Hae-Young Lee Kyung-Hee
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Abstract
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Oxygen is essential for human life, yet it is dangerous to all aerobic organisms. This is because some oxygen is metabolized to oxygen-derived free radicals and other free radical species which, in excess, can cause the cell injury and be opposed by antioxidant defence systems. Nitric oxide (NO¡¤) is blown to the oxidant injury via production of the potent oxidant peroxynitrite (ONOO-). In this study, 3-morpholinosydnonimine (SIN-1), 2,2¡¯-azobis[2,4- dimethylvaleronitrile) (AMVN), sodium nitroprusside (SNP), H2O2 and tert-butyl hydroperoxide (t-BHP) which can produce intracellular free radicals, the cause of tissue damage and lipid peroxidation, were used for elucidating cytoprotective mechanisms of (-)-epicatechin 3-O-gallate (ECG), (-)-gallocatechin 3-O-gallate (GCG), and (-)- epigallocatechin 3-O-gallate (EGCG) extracted from green tea against free radicals. The treatment with ECG, GCG and EGCG markedly reduced cell damage induced by SIN-1, AMVN, H2O2and t-BHP in cultured AcF2 liver cells. On the other hand, in case of SNP, cell viability was not dependent on the concentration and kinds of green tea polyphenols. Therefore, we can postulate that green tea polyphenols inhibit peroxynitrite formation through their OB- scavenging as well as direct peroxynitrite scavenging.
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KEYWORD
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(-)-Epicatechin 3-O-gallate (ECG), (-)-Gallocatechin 3-O-gallate (GCG), (-)-Epigallocatechin 3-O-gallate (EGCG), Green tea polyphenols, Cytoprotective mechanism
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