Theoretical Study of the Antioxidant Activity of Vitamin E: Reactions of α-Tocopherol with the Hydroperoxy Radical
- 1 February 2005
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of Chemical Theory and Computation
- Vol. 1 (2) , 337-344
Abstract
The reactivity of the hydroperoxy radical with α-tocopherola prototype of the chemical reactions involved in biological antioxidant actionswas studied theoretically. Two pathways were analyzed: hydrogen abstraction from the phenolic hydrogen and hydroperoxy addition to the aromatic ring. The reaction paths for the two mechanisms were traced independently, and the respective thermal rate constants were calculated using variational transition-state theory with multidimensional small-curvature tunneling. The reactivity of the hydroperoxy radical was found to be dominated by the hydrogen abstraction mechanism on α-tocopherol, with a rate constant of 1.5 × 105 M-1 s-1 at 298 K. It was also found that the mechanism of the reaction is not direct but passes through two intermediates, one of which may have a significant role in preventing the pro-oxidant effects of α-tocopherol.Keywords
This publication has 18 references indexed in Scilit:
- Ensemble‐averaged variational transition state theory with optimized multidimensional tunneling for enzyme kinetics and other condensed‐phase reactionsInternational Journal of Quantum Chemistry, 2004
- Theoretical Study of the Trapping of the OOH Radical by Coenzyme QJournal of the American Chemical Society, 2003
- Adiabatic Connection for KineticsThe Journal of Physical Chemistry A, 2000
- Book reviewsFree Radical Biology and Medicine, 2000
- The Unexpected Role of Vitamin E (α-Tocopherol) in the Peroxidation of Human Low-Density LipoproteinAccounts of Chemical Research, 1998
- Endogenous ubiquinol prevents protein modification accompanying lipid peroxidation in beef heart submitochondrial particlesFree Radical Biology and Medicine, 1995
- Three methods to measure RH bond energiesThe Journal of Physical Chemistry, 1994
- Comparison of the efficiencies of several natural and synthetic antioxidants in aqueous SDS [sodium dodecyl sulfate] micelle solutionsJournal of the American Chemical Society, 1988
- Inhibition kinetics of chain-breaking phenolic antioxidants in SDS micelles. Evidence that intermicellar diffusion rates may be rate-limiting for hydrophobic inhibitors such as .alpha.-tocopherolJournal of the American Chemical Society, 1986
- The formation of an enantiomerically pure product of free radical coupling. The chemistry of diphenylcarbene in polycrystalline S-(+)-2-butanolJournal of the American Chemical Society, 1985