Oxidative catabolism of α‐tocopherol in rat liver microsomes

The goal of this study was to clarify the mechanism responsible for the catabolism of α‐tocopherol. The vitamin, bound to albumin, was incubated with rat liver microsomes and appeared to be broken down. Optimal production of the metabolite was obtained when 1 mg of microsomal protein was incubated w...

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Bibliographic Details
Published in:Lipids 2001-04, Vol.36 (4), p.367-372
Main Authors: Van Houte, Hilde, Hoffmann, Edmond, Van Veldhoven, Paul P., Mannaerts, Guy P., Carchon, Hubert, Baes, Myriam I., Declercq, Peter E.
Format: Article
Language:English
Subjects:
alpha-Tocopherol - metabolism
Animals
Chromatography, High Pressure Liquid
Chromatography, Liquid
Magnetic Resonance Spectroscopy
Male
Microsomes, Liver - metabolism
NADP - pharmacology
Oxidation-Reduction
Oxygen - pharmacology
Rats
Rats, Wistar
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Summary:The goal of this study was to clarify the mechanism responsible for the catabolism of α‐tocopherol. The vitamin, bound to albumin, was incubated with rat liver microsomes and appeared to be broken down. Optimal production of the metabolite was obtained when 1 mg of microsomal protein was incubated with 36 μM of α‐tocopherol in the presence of 1.5 mM of NADPH. Chromatographic and mass spectrometric analyses of the metabolite led to the conclusion that it consists of an ω‐acid with an opened chroman ring, although we could not perform nuclear magnetic resonance analysis to confirm this. Our data show that α‐tocopherol is ω‐oxidized to a carboxylic acid and that this process can occur in rat liver microsomes in the presence of NADPH and O2. The oxidation to the quinone structure appears to be a subsequent event that may be artifactual and/or catalyzed by a microsomal enzyme(s).
ISSN:0024-4201
1558-9307
DOI:10.1007/s11745-001-0729-1