Identification and Quantification of the Conjugated Metabolites Derived from Orally Administered Hesperidin in Rat Plasma

Hesperidin is a biologically effective flavonoid. Several studies have reported that dietary hesperidin was converted to conjugated metabolites, such as hesperetin-glucuronides and sulfoglucuronides, during absorption and metabolism. However, the chemical structures of the conjugated metabolites, especially the sites of glucuronidation and sulfoglucuronidation in plasma, were unconfirmed. Therefore, the concentrations of the metabolites conjugated at various sites in plasma could not be individually quantified. In the present study, we identified the chemical structures and concentrations of the major conjugated metabolites in rat plasma after oral administration of hesperidin. Two hesperetin-glucuronides were prepared and identified as hesperetin-7-O-β-d-glucuronide and hesperetin-3‘-O-β-d-glucuronide. Using these authentic compounds, the concentrations of hesperetin-7-O-β-d-glucuronide and hesperetin-3‘-O-β-d-glucuronide in rat plasma were individually determined by liquid chromatography−mass spectromet...