title: Evidence for alpha-tocopherol regeneration reaction of green tea polyphenols in SDS micelles.
abstract: The synergistic antioxidant mechanism of alpha-tocopherol (vitamin E) with green tea polyphenols, i.e., (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), (-)-epigallocatechin gallate (EGCG), and gallic acid (GA), was studied by assaying the kinetics of the reaction of alpha-tocopheroxyl radical with green tea polyphenols by stopped-flow electron paramagnetic resonance, the inhibition of linoleic acid peroxidation by these antioxidants, and the decay of alpha-tocopherol during the peroxidation. It was found that the green tea polyphenols could reduce alpha-tocopheroxyl radical to regenerate alpha-tocopherol with rate constants of 0.45, 1.11, 1.31, 1.91, and 0.43 x 10(2) M(-1) s(-1) for EC, EGC, ECG, EGCG, and GA, respectively, in sodium dodecyl sulfate micelles. In addition, these second-order rate constants exhibited a good linear correlation with their oxidation potentials, suggesting that electron transfer might play a role in the reaction.
authors.affiliation: National Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou, Gansu 730000, Peoples' Republic of China. bozhou@lzu.edu.cn
authors.forename: Bo
authors.initials: B
authors.lastname: Zhou
authors.forename: Long-Min
authors.initials: LM
authors.lastname: Wu
authors.forename: Li
authors.initials: L
authors.lastname: Yang
authors.forename: Zhong-Li
authors.initials: ZL
authors.lastname: Liu
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D004357:Drug Synergism; D004578:Electron Spin Resonance Spectroscopy; D005419:Flavonoids / Q000494:pharmacology*; D005609:Free Radicals / Q000378:metabolism; D007700:Kinetics; D019787:Linoleic Acid / Q000378:metabolism*; D008823:Micelles; D010084:Oxidation-Reduction; D010636:Phenols / Q000494:pharmacology*; D059808:Polyphenols; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry / Q000378:metabolism*; D013662:Tea / Q000737:chemistry*; D014810:Vitamin E / Q000378:metabolism; D024502:alpha-Tocopherol / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D005419:Flavonoids; D005609:Free Radicals; D008823:Micelles; D010636:Phenols; D059808:Polyphenols; D013662:Tea; C066323:tocopheroxy radical; D014810:Vitamin E; D012967:Sodium Dodecyl Sulfate; D019787:Linoleic Acid; D024502:alpha-Tocopherol