In vitro metabolism of sesamin, a sesame seed lignin

IN VITRO METABOLISM OF SESAMIN, A SESAME SEED LIGNAN Sesame seed is a rich source of plant lignans, especially sesamin. This compound has been shown to exert several physiological activities, including anti-oxidative, anti-carcinogenic, blood pressure-lowering, and serum lipid lowering activities. However, the metabolism of sesamin has not been studied in detail and thus the nature of the active compounds behind the beneficial properties has not been fully established. In this study the in vitro metabolism of sesamin was investigated by fermenting pure standard with human fecal inoculum (5%) for 24 hours. The freeze-dried fermentation samples were extracted with diethyl ether and further purified with chromatography on Lipidex 5000. The metabolites of sesamin were identified by GC-MS with authentic reference compounds or by interpretation of mass spectra of trimethylsilylated derivatives. Five metabolites were identified in fecal fermentation extracts of sesamin: mammalian lignans enterolactone and enterodiol, and metabolites S1, S2 and S3. The identification of the metabolites by GC-MS is presented and the possible metabolic route of sesamin to mammalian lignans is proposed. It is concluded that sesamin is an important precursor of mammalian lignans, and sesame seeds are good sources of enterolactone, high plasma and urinary levels of which have been associated with a decreased risk of certain cancers and cardiovascular disease.