In the course of an intensive search for novel antioxidants from plant materials, in particular those used as foods, new types of natural antioxidants have been isolated and identified. Novel lignan type antioxidants have been isolated from sesame seeds and oils, and several phenol glucosides were found to be present in the cultured tissue of the sesame plant. Ellagic acid derivatives and tannins are found to be the main antioxidative components in the herbs, spices and crude drugs. Recently, much attention has been focused on dietary phenolic antioxidants which may be effective in protection from peroxidative damages, especially, from mutagenicity induced during lipid peroxidation. Polyphenol type antioxidants which have o-dihydroxy moiety in the structures, such as elegiac acid derivatives, (-)-epicatechin gallate and (-)epigallocatechin gallate were found to inhibit not only the free-radical chain reaction of cell membrane lipids but also mutagenicity and DNA damaging activity. Moreover, these polyphenols were found to inhibit DNA single-strand cleavage induced by N-hydroxy-2-amino-naphthalene.
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