Harada M, Kan Y, Naoki H, Fukui Y, Kageyama N, Nakai M, Miki W, Kiso Y
Institute for Fundamental Research, Suntory Ltd., Sunbor, Osaka, Japan.
Biosci Biotechnol Biochem. 1999 Jun;63(6):973-7. doi: 10.1271/bbb.63.973.
(+)-Catechin and (-)-epicatechin are known to be biologically effective antioxidants present in the human diet, particularly in wine and tea. We studied the metabolism of these compounds to elucidate the truly active structures in biological fluids by their oral administration to rats. Without any treatment with beta-glucuronidase and sulfatase, a pair of metabolites were detected at much higher concentrations in the plasma, bile, and urine than the originally ingested compounds. Each major metabolite found in the plasma at the highest concentration was excreted in both the bile and urine, and was purified from urine. Their chemical structures were established to be (+)-catechin 5-O-beta-glucuronide and (-)-epicatechin 5-O-beta-glucuronide by MS and NMR analyses. These glucuronide conjugates exhibited high antioxidative activities as superoxide anion radical scavengers like their parent compounds. It is concluded that (+)-catechin 5-O-beta-glucuronide and (-)-epicatechin 5-O-beta-glucuronide are the biologically active in vivo structures of the ingested polyphenolic antioxidants.
已知（+）-儿茶素和（-）-表儿茶素是人类饮食中存在的具有生物活性的抗氧化剂，尤其是在葡萄酒和茶中。我们通过给大鼠口服这些化合物来研究它们的代谢情况，以阐明生物体液中真正具有活性的结构。在未经β-葡萄糖醛酸酶和硫酸酯酶处理的情况下，在血浆、胆汁和尿液中检测到的一对代谢物的浓度比最初摄入的化合物高得多。在血浆中以最高浓度发现的每种主要代谢物都通过胆汁和尿液排出，并从尿液中纯化出来。通过质谱（MS）和核磁共振（NMR）分析确定它们的化学结构为（+）-儿茶素5-O-β-葡萄糖醛酸苷和（-）-表儿茶素5-O-β-葡萄糖醛酸苷。这些葡萄糖醛酸共轭物与其母体化合物一样，作为超氧阴离子自由基清除剂表现出高抗氧化活性。得出的结论是，（+）-儿茶素5-O-β-葡萄糖醛酸苷和（-）-表儿茶素5-O-β-葡萄糖醛酸苷是摄入的多酚类抗氧化剂在体内具有生物活性的结构。
