title: Antioxidant effects of green tea polyphenols on free radical initiated peroxidation of rat liver microsomes.
abstract: Antioxidative effects of the principal polyphenolic components extracted from green tea leaves, i.e. (-)-epicatechin (EC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin gallate (EGCG), (-)-epigallocatechin (EGC), and gallic acid (GA), against free radical initiated peroxidation of rat liver microsomes were studied. The peroxidation was initiated by a water-soluble azo compound 2,2'-azobis(2-amidinopropane hydrochloride (AAPH). The reaction kinetics was monitored by oxygen uptake and formation of malondialdehyde (MDA). Kinetic analysis of the antioxidation process demonstrates that these green tea polyphenols (GOHs), especially EC and ECG which bear ortho-dihydroxyl functionality, are good antioxidants for microsomal peroxidation. The antioxidant synergism of these GOHs with the endogenous alpha-tocopherol (TOH) (vitamin E) is also discussed.
authors.affiliation: National Laboratory of Applied Organic Chemistry, Lanzhou University, Gansu 730000, Lanzhou, People's Republic of China.
authors.forename: Yu Jun
authors.initials: YJ
authors.lastname: Cai
authors.forename: Lan Ping
authors.initials: LP
authors.lastname: Ma
authors.forename: Li Fen
authors.initials: LF
authors.lastname: Hou
authors.forename: Bo
authors.initials: B
authors.lastname: Zhou
authors.forename: Li
authors.initials: L
authors.lastname: Yang
authors.forename: Zhong Li
authors.initials: ZL
authors.lastname: Liu
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002392:Catechin / Q000031:analogs & derivatives; D005260:Female; D005419:Flavonoids; D005609:Free Radicals / Q000378:metabolism; D007700:Kinetics; D015227:Lipid Peroxidation / Q000187:drug effects*; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism*; D010636:Phenols / Q000494:pharmacology*; D011108:Polymers / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013662:Tea / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D005419:Flavonoids; D005609:Free Radicals; D010636:Phenols; D011108:Polymers; D013662:Tea; D002392:Catechin