title: Tissue distribution of vitamin E metabolites in rats after oral administration of tocopherol or tocotrienol.
abstract: We previously found that 2,7,8-trimethyl-2(2'-carboxyethyl)-6-hydroxychroman (γCEHC), a metabolite of the vitamin E isoforms γ-tocopherol or γ-tocotrienol, accumulated in the rat small intestine. The aim of this study was to evaluate tissue distribution of vitamin E metabolites. A single dose of α-tocopherol, γ-tocopherol or a tocotrienol mixture containing α- and γ-tocotrienol was orally administered to rats. Total amounts of conjugated and unconjugated metabolites in the tissues were measured by HPLC with an electrochemical detector, and 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (trolox) was used as an internal standard. Twenty-four hours later, the vitamin E isoforms were detected in most tissues and in the serum. However, 2,5,7,8-tetramethyl-2(2'-carboxyethyl)-6-hydroxychroman (αCEHC), a metabolite of α-tocopherol or α-tocotrienol, and γCEHC accumulated in the serum and in some tissues including the liver, small intestine and kidney. Administration of α-tocopherol increased the γCEHC concentration in the small intestine, suggesting that α-tocopherol enhances γ-tocopherol catabolism. In contrast, ketoconazole, an inhibitor of cytochrome P450 (CYP)-dependent vitamin E catabolism, markedly decreased the γCEHC concentration. These data indicate that vitamin E metabolite accumulates not only in the liver but also in the small intestine and kidney. We conclude that some dietary vitamin E is catabolized to carboxyethyl-hydroxychroman in the small intestine and is secreted into the circulatory system.
authors.affiliation: Department of Nutritional Sciences, Nagoya University of Arts and Sciences, Nisshin, Japan.
authors.forename: Tomono
authors.initials: T
authors.lastname: Uchida
authors.forename: Saki
authors.initials: S
authors.lastname: Nomura
authors.forename: Tomio
authors.initials: T
authors.lastname: Ichikawa
authors.forename: Chisato
authors.initials: C
authors.lastname: Abe
authors.forename: Saiko
authors.initials: S
authors.lastname: Ikeda
mesh_terms: D058888:14-alpha Demethylase Inhibitors / Q000494:pharmacology; D000284:Administration, Oral; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002839:Chromans / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism; D007421:Intestine, Small / Q000187:drug effects / Q000378:metabolism; D007668:Kidney / Q000187:drug effects / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009928:Organ Specificity; D011422:Propionates / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D024508:Tocotrienols / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*; D014810:Vitamin E / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000097:blood / Q000378:metabolism*; D024502:alpha-Tocopherol / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*; D024504:gamma-Tocopherol / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*
chemical_list: D058888:14-alpha Demethylase Inhibitors; D002839:Chromans; D011422:Propionates; D024508:Tocotrienols; D014810:Vitamin E; C107690:2,7,8-trimethyl-2-(beta-carboxyethyl)-6-hydroxychroman; C084852:2,5,7,8-tetramethyl-2-(2'-carboxyethyl)-6-hydroxychroman; C013649:plastochromanol 8; D024504:gamma-Tocopherol; C082032:tocotrienol, alpha; D024502:alpha-Tocopherol