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标题：Dietary flavonoids with a catechol structure increase {alpha}-tocopherol in rats and protect the vitamin from oxidation in vitro
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作者：Frank, Jan ; Budek, Alicja ; Lundh, Torbjorn 等
期刊名称：JLR Papers In Press
印刷版ISSN：0022-2275
电子版ISSN：1539-7262
出版年度：2006
卷号：47
期号：12
页码：2718-2725
DOI：10.1194/jlr.M600291-JLR200
出版社：American Society for Biochemistry and Molecular Biology
摘要：To identify dietary phenolic compounds capable of improvingvitamin E status, male Sprague-Dawley rats were fed for 4 weekseither a basal diet (control) with 2 g/kg cholesterol and anadequate content of vitamin E or the basal diet fortified withquercetin (Q), (–)-epicatechin (EC), or (+)-catechin (C)at concentrations of 2 g/kg. All three catechol derivativessubstantially increased concentrations of ${alpha}$ -tocopherol ( ${alpha}$ -T) inblood plasma and liver. To study potential mechanisms underlyingthe observed increase of ${alpha}$ -T, the capacities of the flavonoidsto i) protect ${alpha}$ -T from oxidation in LDL exposed to peroxyl radicals,ii) reduce ${alpha}$ -tocopheroxyl radicals ( ${alpha}$ -T ^· ) in SDS micelles,and iii) inhibit the metabolism of tocopherols in HepG2 cellswere determined. All flavonoids protected ${alpha}$ -T from oxidationin human LDL ex vivo and dose-dependently reduced the concentrationsof ${alpha}$ -T ^· . None of the test compounds affected vitaminE metabolism in the hepatocyte cultures. In conclusion, fortificationof the diet of Sprague-Dawley rats with Q, EC, or C considerablyimproved their vitamin E status. The underlying mechanism doesnot appear to involve vitamin E metabolism but may involve directquenching of free radicals or reduction of the ${alpha}$ -T ^· by the flavonoids. Supplementary key words (+)-catechin • cytochrome P₄₅₀ • (–)-epicatechin • hepatocytes • HepG2 • quercetin • tocopherol- ${omega}$ -hydroxylase • tocopheroxyl radical Abbreviations: C, (+)-catechin; CYP, cytochrome P₄₅₀; EC, (–)-epicatechin; Q, quercetin; ${alpha}$ -T, ${alpha}$ -tocopherol; ${alpha}$ -T ^· , ${alpha}$ -tocopheroxyl radical; UV, ultraviolet