No reduction of alpha-tocopherol quinone by glutathione in rat liver microsomes

R.I.M. van Haaften, C.T.A. Evelo, G.R.M.M. Haenen, A. Bast

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Abstract

No reduction of alpha-tocopherol quinone by glutathione in rat liver microsomes.

van Haaften RI, Evelo CT, Haenen GR, Bast A.

Department of Pharmacology and Toxicology, Faculty of Medicine, Universiteit Maastricht, P.O. Box 616, 6200 MD, Maastricht, The Netherlands. r.vanhaaften@farmaco.unimaas.nl

The cell membrane is protected against lipid peroxidation by endogenous antioxidants such as vitamin E (alpha-tocopherol). The oxidised form of alpha-tocopherol (alpha-tocopherol quinone) does not have this antioxidant function. However, the literature indicates that alpha-tocopherol quinone can be reduced to alpha-tocopherol in vivo and thereby will add to the total antioxidant potential (Moore AN, Ingold KU. Free Radic Biol Med 1997;22:931-4). We found that GSH (reduced glutathione) did not mediate the reduction of alpha-tocopherol quinone, either directly in solution or in rat liver microsomes fortified with alpha-tocopherol quinone. This renders GSH a less likely candidate for alpha-tocopherol quinone reduction in vivo. In addition, alpha-tocopherol quinone did not enhance GSH-dependent protection against lipid peroxidation, either in control microsomes, or in vitamin E-extracted microsomes. Indeed, alpha-tocopherol quinone blocked GSH-dependent protection against lipid peroxidation in vitamin E-extracted microsomes. This indicates that alpha-tocopherol quinone can act as a pro-oxidant.
Original languageEnglish
Pages (from-to)715-719
Number of pages5
JournalBiochemical Pharmacology
Volume61
DOIs
Publication statusPublished - 1 Jan 2001

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