Faculty Collaboration Database

The oxidation of alpha-tocopherol and trolox by peroxynitrite. Arch Biochem Biophys 1994 Oct;314(1):153-8

Date

10/01/1994

Pubmed ID

7944387

DOI

10.1006/abbi.1994.1423

Scopus ID

2-s2.0-0028172263 (requires institutional sign-in at Scopus site)   102 Citations

Abstract

Peroxynitrite reacts rapidly with alpha-tocopherol to generate a mixture of species. The predominant products are 8a-methoxytocopherone in methanol and alpha-tocopherylquinone in acetonitrile. Only a small fraction (about 2% of original alpha-tocopherol) was detected as alpha-tocopheroxyl radical in either solvent. We propose that peroxynitrite oxidizes alpha-tocopherol in a two-electron process yielding the alpha-tocopherone cation. The two-electron oxidation may be either concerted or sequential. The fate of the alpha-tocopherone cation is solvent dependent. In acetonitrile it undergoes hydrolysis, in the presence of trace amounts of water, to form alpha-tocopherylquinone. In methanol it undergoes nucleophilic addition to yield 8a-methoxytocopherone. Our data suggest that two-electron oxidation of alpha-tocopherol by peroxynitrite represents the major pathway, whereas one-electron oxidation to generate alpha-tocopheroxyl radical is a minor pathway. The biological consequences of two-electron oxidation of alpha-tocopherol are discussed.

Author List

Hogg N, Joseph J, Kalyanaraman B

Authors

Neil Hogg PhD Senior Associate Dean, Professor in the Biophysics department at Medical College of Wisconsin
Balaraman Kalyanaraman PhD Professor in the Biophysics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Acetonitriles
Chromans
Chromatography, High Pressure Liquid
Electron Spin Resonance Spectroscopy
Free Radicals
Hydrolysis
Methanol
Nitrates
Oxidation-Reduction
Solvents
Vitamin E