Title: Polyunsaturated fatty acid alkoxyl radicals exist as carbon-centered epoxyallylic radicals: a key step in hydroperoxide-amplified lipid peroxidation.

Authors: Wilcox, A L; Marnett, L J

Published In Chem Res Toxicol, (1993 Jul-Aug)

Abstract: 13-Hydroperoxyoctadeca-9,11,15-trienoic acid was reacted with a catalytic amount of 5,10,15,20-tetraphenyl-21H,23H-porphyrin iron(III) chloride in dichloromethane containing 2,4,6-tri-tert-butylphenol. The principal products were identified as 13-oxooctadeca-9,11,15-trienoic acid, 13-oxotrideca-9,11-dienoic acid, and a series of isomeric epoxyaryl ethers [9-(2,4,6-tri-tert-butylphenoxy)-12,13-epoxyoctadec-10-enoic acids and 11-(2,4,6-tri-tert-butylphenoxy)-12,13-epoxyoctadec-9-enoic acids]. The epoxyaryl ethers are coupling products of 2,4,6-tri-tert-butylphenoxyl radical and an epoxyallylic radical formed by cyclization of an intermediate alkoxyl radical. The high yield of epoxyaryl ethers relative to 13-oxotrideca-9,11-dienoic acid suggests the equilibrium between alkoxyl radical and epoxyallylic radical lies predominantly toward epoxyallylic radical. This cyclization appears to be a key step in the amplification of lipid peroxidation by polyunsaturated fatty acid hydroperoxides.

PubMed ID: 8374035

MeSH Terms: Antioxidants; Chromatography, High Pressure Liquid; Cyclization; Fatty Acids, Unsaturated/chemistry*; Free Radicals; Hydrogen Peroxide; Iron Chelating Agents; Linolenic Acids; Lipid Peroxidation*; Lipid Peroxides; Phenols/chemistry; Porphyrins/chemistry