Antioxidation reaction mechanism studies of phenolic lignans, identification of antioxidation products of secoisolariciresinol from lipid oxidation

The chain-breaking antioxidation reaction mechanism of a phenolic lignan in a lipid oxidation system was investigated. The 2,2′-azobis(isobutyronitrile) (AIBN)-induced radical oxidation reaction in a large amount of ethyl linoleate in the presence of secoisolariciresinol, one of the potent antioxidative lignans widely distributed in edible plants, produced two types of peroxides as radical termination products, as well as a cyclic derivative. The isolation and structure determination of the peroxides revealed that they have a peroxide linkage with ethyl linoleate or isobutyronitrile at the 1-position of the benzene ring of secoisolariciresinol. The cyclic derivative was also identified as lariciresinol by spectroscopic analysis. Based on the chemical structures of these products, a reaction pathway for the antioxidation reaction of secoisolariciresinol in oxidising lipid media was proposed.