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A New , Sensitive Method for Lignan Metabolite Detection of Flaxseed-Fed Mice Using LC / MS / MS

Dietary phytochemicals such as polyphenols, carotenoids, saponins and glucosinolates have been suggested to play important roles in human health and may contribute to the prevention of diseases. While the intrinsic food bioactives have been found to act as strong antioxidants and exert various activities in vitro, the actual bioactive forms in vivo are not clear. In fact, it is often the metabolites of a phytochemical that exert bioactivities. Among the various bioactive polyphenols found in plant-based foods, lignans are one of the most important subgroups. For example, plant lignans such as secoisolarisiresinol diglucoside (SDG) glycoside in flax seed are not free molecules but part of the lignan complex. These lignan glycosides are released by digestive enzymes and further hydrolyzed to produce the aglycones secoisolariciresinol (SEC) and matairesinol (MAT), which are converted by the microorganisms in the human colon to the bioactive mammalian lignans enterodiol (END) and enterolactone (ENL) (Figure 1).1 However, due to low bioavailability, metabolites of lignans are at minute concentrations in biological fluid samples. This presents a significant challenge for food and nutritional scientists using conventional detectors coupled with liquid chromatography. LC/MS/MS technology provides an excellent alternative because of its sensitivity.2 Liquid Chromatography/ Mass Spectrometry A P P L I C A T I O N N O T E