Schultz M, Leist M, Petrzika M, Gassmann B, Brigelius-Flohé R
Department of Vitamins and Atherosclerosis, German Institute of Human Nutrition, Potsdam-Rehbrücke, Germany.
Am J Clin Nutr. 1995 Dec;62(6 Suppl):1527S-1534S. doi: 10.1093/ajcn/62.6.1527S.
Previously, the metabolism of alpha-tocopherol was considered to involve the opening of the chroman structure because of its oxidation to tocopherylquinone. In contrast, we describe here 2,5,7,8-tetramethyl-2(2'-carboxyethyl)-6-hydroxychroman (alpha-CEHC) as the major urinary metabolite of alpha-tocopherol that appears in human urine after vitamin E supplementation. It is formed directly from alpha-tocopherol without previous oxidative splitting of the chroman ring. The correlation of alpha-tocopherol intake, plasma alpha-tocopherol concentrations, and urinary excretion of alpha-CEHC in human volunteers supplemented with RRR-alpha-tocopherol dosages ranging from 0 to 800 mg/d was examined. HPLC and gas chromatography-mass spectroscopy analysis revealed that alpha-CEHC was only excreted when a plasma threshold of 7-9 mumol alpha-tocopherol/g total lipid was exceeded. This concentration was obtained by a daily intake of approximately 50-150 mg alpha-tocopherol. We suggest that alpha-CEHC excretion indicates a saturated binding capacity of vitamin E in the plasma and thus may be considered to be a marker of optimum vitamin E intake.
以前，由于α-生育酚氧化生成生育酚醌，其代谢过程被认为涉及苯并二氢吡喃结构的开环。相比之下，我们在此描述2,5,7,8-四甲基-2(2'-羧乙基)-6-羟基苯并二氢吡喃（α-CEHC）是α-生育酚的主要尿液代谢产物，在补充维生素E后出现在人类尿液中。它直接由α-生育酚形成，无需事先对苯并二氢吡喃环进行氧化裂解。研究了补充剂量范围为0至800 mg/d的RRR-α-生育酚的人类志愿者中α-生育酚摄入量、血浆α-生育酚浓度与α-CEHC尿液排泄之间的相关性。高效液相色谱和气相色谱-质谱分析表明，只有当血浆中α-生育酚阈值超过7-9 μmol/g总脂质时，α-CEHC才会排泄。通过每日摄入约50-150 mgα-生育酚可达到该浓度。我们认为，α-CEHC排泄表明血浆中维生素E的结合能力已饱和，因此可被视为最佳维生素E摄入量的标志物。
