Metabolism of dietary flavonoids

Manach C, Donovan JL (2004) Pharmacokinetics and metabolism of dietary flavonoids in humans. Free Radic Res 38 771-785. 

Breinholt, V.M., Offord, E.A., Brouwer, C., Nielsen, S.E., Brosen, K., and Eriedberg, T., In vitro investigation of cytochrome P450-mediated metabolism of dietary flavonoids. Food Chem. Toxicol, 40, 609, 2002. 

In general, the metabolism of dietary flavonoids may be summarized as shown in Fig. (15). 

Fig. (15). Metabolism of dietary flavonoids. GlcA = glucuronic acid UGT - uridine 5 -diphospoglucuronosyl transferase Met = methyl Sulf = sulfate COMT = catechol-O-methyl transferase PST = phenol sulfo transferase...

Day AJ, Mellon F, Barron D, Sarrazin G, Morgan MRA, Williamson G. 2001. Human metabolism of dietary flavonoids identification of plasma metabolites of quercetin. Free Radic Res 35 941-952. 

Nemeth, K. Plumb, G.W. Berrin, J.-G. Juge, N. Jaeob, R. Naim, H.Y. Williamson, G. Swallow, D.M. Kroon, P.A. 2003. Deglyeosylation by small intestinal epithelial eell P-glucosidases is a critieal step in the absorption and metabolism of dietary flavonoid glycosides in humans. Eur. J. Nutr. 42 29-42. 

Absorption and metabolism of dietary flavonoids in the digestive system... 

HOLLMAN p c and KATAN M B (1997) Absorption, metabolism and health effects of dietary flavonoids in man , Biomed Pharmacother, 51, 305-10. 

Recent evidence on the bioavailability and metabolism of these compounds in vivo suggests that dietary flavonoids are less likely to act as antioxidants. Most flavonoids may not have significant antioxidant activity in vivo for two reasons (1) bioavailability of dietary flavonoids is very poor (their concentration in vivo... 

Whatever the mechanism of action for the inhibition of 5-lipoxygenase by flavonoids, it appears to be distinct from the antioxidant properties of these compounds. The results comparing antioxidant activity with leukotriene inhibitory activity clearly demonstrate this distinction. The profound effects of metabolic transformation on the anti-inflammation activity of dietary flavonoids such as quercetin must also be considered in relation to in vitro studies, and further highlights the need to use actual metabolic forms of flavonoids rather than the free aglycone or glycosides occurring in the diet. 

Cermak, R. Effect of dietary flavonoids on pathways involved in drug metabolism. Expert Opin. Drug Toxicol. 4, 17-35 (2008)... 

Nielsen SE. Metabolism and biomarker studies of dietary flavonoids, Ph.D. dissertation. Danish Veterinary and Food Administration, Denmark, 1998. 

Williamson G, Day AJ, Plumb GW, Couteau D. Human metabolic pathways of dietary flavonoids and cinnamates. Biochem Soc Trans 2000 28 16-22. 

Bioavailability of dietary flavonoids is mostly dependent on the efficacy of intestinal absorption by epithelial cells in the small intestine and large intestine (Manach Donovan, 2004). Fig. 13.4 shows the general concept for the metabolic fate of flavonoids in the digestive system. The major site for intestinal absorption is believed to be the large... 

The limited source of knowledge on the absorption and metabolism of flavonoids has been generated by studying isolated flavonoids and individual foods and more studies will be needed on the investigation of the absorption and metabolism combining various flavonoids and foods. To date, data from animal models and in vitro experiments indicate considerable differences among the different types of dietary flavonoids so that the most abundant ones in the diet do not necessarily produce the highest concentration of flavonoids or their metabolites in vivo. 

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