Quantification of the α- and γ-tocopherol metabolites 2,5,7,8-tetramethyl-2-(2′-carboxyethyl)-6-hydroxychroman and 2,7,8-trimethyl-2-(2′-carboxyethyl)-6-hydroxychroman in human

alpha- and gamma-tocopherol are the major vitamin E compounds found in human blood and tissues. The metabolites are 2,5,7,8-tetramethyl-2-(2'-carboxyethyl)6-hydroxychroman (alpha-CEHC) and 2,7,8-trimethyl-2-(2'carboxyethyl)-6-hydroxychroman (gamma-CEHC, LLU-alpha), respectively, alpha-CEHC is excreted mainly as glucuronide or sulfate conjugates in the urine. Here we describe a sensitive and reliable method to analyze alpha-and gamma-CEHC in human serum. The concentration of gamma-CEHC in human serum is in the range of 5-10 pmol/ml but increases significantly up to 200 pmol/ml upon supplementation with RRR-alpha-tocopherol, About one-third of the alpha-CEHC circulating in the blood is present as a glucuronide conjugate. Baseline levels of gamma-CEHC are about 50 to 85 pmol/ml. (C) 1999 Academic Press.