Oxidative metabolites and genotoxic potential of mammalian and plant lignans in vitro

Certain plant lignans, e.g. secoisolariciresinol and matairesinol, are converted by the intestinal microflora to the mammalian lignans enterodiol and enterolactone, which are associated with beneficial health effects in humans. The metabolism of both mammalian and plant lignans in animals and humans is poorly understood, and most studies so far have focused on the conjugation of these diphenolic compounds. However, recent studies have demonstrated that mammalian and plant lignans are good substrates for cytochrome P450-mediated reactions, leading to numerous products of aliphatic and aromatic hydroxylation with microsomes in vitro. The current knowledge of the oxidative metabolism of food-related lignans is briefly reviewed in this paper, including published as well as unpublished data from our laboratory. Moreover, data on the genotoxic potential of the mammalian and plant lignans, determined at various endpoints in cultured mammalian cells, are included in this review.