Mechanism of Activation of Flavonoid Conjugates through Interaction with Macrophages

Abstract

Much attention has long been paid on the biological activity of dietary flavonoids in human health. Although flavonoids and other polyphenols are metabolized into their phase-II conjugates, glucuronides and sulfates, after absorption in vivo, the actions of these conjugates underlying the health-beneficial activity, including the target sites/molecules, have not been understood. Here, this review summarized our recent findings on the molecular mechanisms for specific accumulation of quercetin-3-glucuronide, a major quercetin metabolite found in human plasma, in macrophages and the following deconjugation into the biologically active aglycones. Understanding how flavonoid conjugates could exhibit their biological activity in specific tissues and cells will provide useful information in developing new strategies for the effective utilization of the biological activity of natural flavonoids in daily diet.