Characterization of cellular uptake and distribution of vitamin E.
We previously reported that tocotrienols acted as more potent inhibitors against selenium deficiency-induced cell death than the corresponding tocopherol isoforms (J. Biol. Chem. 2003;278:39428-39434). In the present study, we first compared the differences in the cellular uptake between alpha-tocopherol (alpha-Toc) and alpha-tocotrienol (alpha-Toc-3). The initial rate of cellular uptake of alpha-Toc-3 was 70-fold higher than that of alpha-Toc. Subcellular fractionation analysis of alpha-Toc-3 and alpha-Toc-fortified cells showed similar cellular distribution of these antioxidants, which was directly proportional to the lipid distribution. The cells containing similar amounts of alpha-Toc-3 and alpha-Toc showed similar resistance against the oxidative stress caused by peroxides. These results suggest that the apparent higher cytoprotective effect of alpha-Toc-3 than alpha-Toc is primarily ascribed to its higher cellular uptake.
Saito
Yoshiro
Y
Human Stress Signal Research Center, National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 Japan. yoshiro-saito@aist.go.jp
Yoshida
Yasukazu
Y
Nishio
Keiko
K
Hayakawa
Mieko
M
Niki
Etsuo
E
D000975:Antioxidants / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology; D002458:Cell Fractionation; D002470:Cell Survival; D006801:Humans; D019169:Jurkat Cells; D018384:Oxidative Stress / Q000187:drug effects; D013347:Subcellular Fractions / Q000737:chemistry* / Q000378:metabolism*; D024508:Tocotrienols; D014810:Vitamin E / Q000031:analogs & derivatives* / Q000032:analysis* / Q000378:metabolism* / Q000494:pharmacology; D024502:alpha-Tocopherol / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology
D000975:Antioxidants; D024508:Tocotrienols; D014810:Vitamin E; C082032:tocotrienol, alpha; D024502:alpha-Tocopherol