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Iron‐catalyzed reaction products of α‐tocopherol with methyl 13( S )‐hydroperoxy‐9( Z ),11( E )‐octadecadienoate
Author(s) -
Yamauchi Ryo,
Yamamoto Norio,
Kato Koji
Publication year - 1995
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02536297
Subject(s) - catalysis , lipidology , tocopherol , chemistry , clinical chemistry , organic chemistry , methyl oleate , medicinal chemistry , antioxidant , vitamin e , biochemistry
α‐Tocopherol was reacted with methyl 13( S )‐hydroperoxy‐9( Z ),11( E )‐octadecadienoate in the presence of an iron‐chelate, Fe(III)‐acetylacetonate, at 37°C in benzene. The reaction was carried out either aerobically or anaerobically. The main products of α‐tocopherol under air were isolated and identified as two stereoisomers of 4a,5‐epoxy‐8a‐hydroperoxy‐α‐tocopherone, four stereoisomers of methyl 9‐(8a‐dioxy‐α‐tocopherone)‐12,13‐epoxy‐10( E )‐octadecenoate, four stereoisomers of methyl 11‐(8a‐dioxy‐α‐tocopherone)‐12,13‐epoxy‐9( Z )‐octadecenoate, two stereoisomers of methyl 13( S )‐(8a‐dioxy‐α‐tocopherone)‐9( Z ),11( E )‐octadecadinoate, and α‐tocopherol dimer. Besides the 8a‐(lipid‐peroxy)‐α‐tocopherones, two stereoisomers of methyl 11‐(α‐tocopheroxy)‐12( S ),13( S )‐epoxy‐9( E )‐octadecenoate, two stereoisomers of methyl 9‐(α‐tocopheroxy)‐12( S ),13( S )‐epoxy‐10( E )‐octadecenoate, and two isomers of methyl (α‐tocopheroxy)‐octadecadienoate were obtained under nitrogen atmosphere. The results indicate that the peroxyl radicals from lipid hydroperoxides prefer to react with the 8a‐carbon radical of α‐tocopherol and the carbon‐centered radicals react with the phenoxyl radical of α‐tocopherol.