title: Location of α-tocopherol and α-tocotrienol to heterogeneous cell membranes and inhibition of production of peroxidized cholesterol in mouse fibroblasts.
abstract: BACKGROUND
  α-Tocopherol (α-T) and α-tocotrienol (α-T3) are well recognized as lipophilic antioxidants. Nevertheless, there is limited knowledge on their location in heterogeneous cell membranes. We first investigated the distribution of α-T and α-T3 to the cholesterol-rich microdomains (lipid rafts and caveolae) of heterogeneous cell membranes by incubating these antioxidants with cultured mouse fibroblasts.
  
  
  RESULTS
  Levels of cellular uptake for α-T and α-T3 were adjusted to the same order, as that of the latter was much more efficient than that of the former in the cultured cells. After ultracentrifugation, α-T and α-T3 were partitioned to the microdomain fractions. When the distribution of α-T and α-T3 was further confirmed by using methyl-β-cyclodextrin (which removes cholesterol from membranes), α-T was suggested to be distributed to the microdomains (approx. 9% of the total uptake). The same treatment did not affect α-T3 content in the microdomain fractions, indicating that α-T3 is not located in these cholesterol-rich domains. However, α-T and α-T3 significantly inhibited the production of peroxidized cholesterol when cells were exposed to ultraviolet-A light.
  
  
  CONCLUSIONS
  These results suggest that α-T and α-T3 can act as membranous antioxidants against photo-irradiated cholesterol peroxidation irrespective of their distribution to cholesterol-rich microdomains.
authors.affiliation: Department of Food Science, Institute of Health Bioscience, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, 770-8503 Japan ; School of Food and Nutrition Sciences, University of Shizuoka, Shizuoka, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Nakamura
authors.affiliation: Department of Food Science, Institute of Health Bioscience, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, 770-8503 Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Noma
authors.affiliation: Department of Food Science, Institute of Health Bioscience, Tokushima University Graduate School, 3-18-15 Kuramoto-cho, Tokushima, 770-8503 Japan.
authors.forename: Junji
authors.initials: J
authors.lastname: Terao
keywords: Cholesterol hydroperoxide; Lipid rafts; Microdomains; Ultraviolet (UV)-A irradiation; α-Tocopherol; α-Tocotrienol