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A. E. MITCHELL, Dept. of Food Science & Technology, Univ. of California, Davis, 1 Shields Ave., 126 Cruess Hall, Davis, CA 95616 Numerous human clinical studies demonstrate that the consumption of polyphenols associated with fruits, vegetables, tea, cocoa, and soy provide health benefits. These benefits are evaluated by measuring biomarkers such as plasma antioxidant status, platelet aggregation, markers of inflammation, and vascular responsiveness. To date, the biological mechanisms responsible for these varied effects remain unclear, and are the central focus of many research efforts. It is increasing evident that flavonoid structure is a critical determinant in absorption, bioavailability and biotransformation. Biotransformation of flavonoids, results in an array of metabolites that circulate in plasma and likely contribute to biological activity of these compounds. The analysis of flavonoids and their metabolites in biological tissue is complex due to the range of metabolites that are possible (e.g. glucuronides, sulfates, methylated species, glycine conjugates, and glutathione conjugates). However, identification of flavonoid metabolites in tissues is critical for assessing biological activity and directing research efforts for their synthesis and evaluation. The application of LC/MS/MS utilizing select ion monitoring (SIM) for the identification of an extended range of flavonoids and their metabolites in biological fluids will be discussed. We describe the identification of more than 20 quercetin and kaempferol metabolites in the urine of 6 volunteers 4 hours after the consumption of 200 g of onion (~70 mg quercetin and ~1 mg kaempferol). Metabolite profiles differ in the composition, and relative quantities of metabolites between volunteers described in this study. Results indicate that urinary metabolite profiles can be used to gain information on absorption, bioavailability and inter-individual biotransformation capacity. This approach offers investigators a non-invasive tool to explore relationships between diet and “protection” via enhanced detoxification capacity.
Session 45, Health benefits of fruits and vegetables: Biological activity of phytonutrients
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |