title: Dietary alpha-tocopherol decreases alpha-tocotrienol but not gamma-tocotrienol concentration in rats.
abstract: We previously showed that alpha- and gamma-tocotrienols accumulate in adipose tissue and skin but not in plasma or other tissues of rats fed a tocotrienol-rich fraction extracted from palm oil containing alpha-tocopherol and alpha- and gamma-tocotrienols. To clarify the nature of tocotrienol metabolism, we studied the distribution of alpha- or gamma-tocotrienol in rats fed alpha- or gamma-tocotrienol without alpha-tocopherol, and the effect of alpha-tocopherol on their distribution. Wistar rats (4-wk-old) were fed a diet with 50 mg alpha-tocotrienol/kg alone or with 50 mg alpha-tocopherol/kg in expt. 1, and a diet with 50 mg gamma-tocotrienol/kg alone or with 50 mg alpha-tocopherol/kg in expt. 2, for 8 wk. alpha-Tocotrienol was detected in various tissues and plasma of the rats fed alpha-tocotrienol alone, and the alpha-tocotrienol concentrations in those tissues and plasma decreased (P < 0.05) by the dietary alpha-tocopherol in the rats fed alpha-tocotrienol with alpha-tocopherol. However, gamma-tocotrienol preferentially accumulated in the adipose tissue and skin of the rats fed gamma-tocotrienol alone, and the dietary alpha-tocopherol failed either to decrease (P >/= 0.05) gamma-tocotrienol concentrations in the adipose tissue and skin or to increase (P >/= 0.05) in the urinary excretion of 2,7,8-trimethyl-2(2'-carboxymethyl)-6-hydroxycroman, a metabolite of gamma-tocotrienol, in the rats fed gamma-tocotrienol with alpha-tocopherol. These data suggest that alpha-tocopherol enhances the alpha-tocotrienol metabolism but not the gamma-tocotrienol metabolism in rats.
authors.affiliation: Department of Food and Nutrition, Sugiyama Jogakuen University, Chikusa-ku, Nagoya, Japan.
authors.forename: Saiko
authors.initials: S
authors.lastname: Ikeda
authors.forename: Tomoko
authors.initials: T
authors.lastname: Tohyama
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yoshimura
authors.forename: Kimio
authors.initials: K
authors.lastname: Hamamura
authors.forename: Kouichi
authors.initials: K
authors.lastname: Abe
authors.forename: Kanae
authors.initials: K
authors.lastname: Yamashita
mesh_terms: D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology*; D001835:Body Weight / Q000187:drug effects; D002839:Chromans / Q000097:blood / Q000493:pharmacokinetics*; D004032:Diet; D008297:Male; D011770:Pyruvate Kinase / Q000097:blood; D051381:Rats; D017208:Rats, Wistar; D014018:Tissue Distribution; D024508:Tocotrienols; D014810:Vitamin E / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics*; D024502:alpha-Tocopherol / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D002839:Chromans; D024508:Tocotrienols; D014810:Vitamin E; C013649:plastochromanol 8; C082032:tocotrienol, alpha; D011770:Pyruvate Kinase; D024502:alpha-Tocopherol