γ-Tocopherol Detoxification of Nitrogen Dioxide: Superiority to α-Tocopherol

In the vitamin E group, α-tocopherol is generally considered to be the most potent antioxidant with the highest vitamin bioactivity, yet γ-tocopherol is produced in greater amounts by many plants and is the principal tocopherol in the United States diet. This report describes a fundamental differenc...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1993-03, Vol.90 (5), p.1771-1775
Main Authors: Cooney, Robert V., Franke, Adrian A., Harwood, Patricia J., Hatch-Pigott, Virginia, Custer, Laurie J., Mordan, Lawrence J.
Format: Article
Language:English
Subjects:
alpha -tocopherol
Analytical, structural and metabolic biochemistry
Animals
Antioxidants
Biochemistry
Biological and medical sciences
Cell Line
Cell Transformation, Neoplastic
Coenzymes, vitamins
comparison
detoxification
Dioxides
fibroblasts
Fundamental and applied biological sciences. Psychology
gamma -tocopherol
Hexanes
In Vitro Techniques
Mice
nitric oxide
Nitric Oxide - chemistry
Nitrites
Nitrogen
nitrogen dioxide
Nitrogen Dioxide - chemistry
Nitrogen oxides
Other biological molecules
Tocopherols
Tumors
Vitamin E
Vitamin E - chemistry
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Summary:In the vitamin E group, α-tocopherol is generally considered to be the most potent antioxidant with the highest vitamin bioactivity, yet γ-tocopherol is produced in greater amounts by many plants and is the principal tocopherol in the United States diet. This report describes a fundamental difference in the chemical reactivities of α-tocopherol and γ-tocopherol with nitrogen dioxide (NO2), which leads to the formation of a nitrosating agent from α-tocopherol, but not from γ-tocopherol. Nitric oxide (NO) is a major product of the reaction of γ-tocopherol with NO2, while α-tocopherol reacts with NO2to form an intermediate tocopheroxide analogue. The biological significance of γ-tocopherol is suggested by limited epidemiological data as well as the observation that it is a more potent inhibitor than α-tocopherol of neoplastic transformation during the postinitiation phase in 3-methylcholanthrene-treated C3H/10T1/2 murine fibroblasts. This latter property suggests the superiority of γ-tocopherol in a mammalian biological assay and a role for endogenous NO production in promotion of neoplastic transformation.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.90.5.1771