Pharmacokinetic Profile of Eight Phenolic Compounds and Their Conjugated Metabolites after Oral Administration of Rhus verniciflua Extracts in Rats.

Rhus verniciflua (Toxicodendron vernicifluum) is a medicinal tree popularly used in Asian countries such as China, Japan, and Korea as a food additive or herbal medicine because of its beneficial effects. R. verniciflua extract (RVE) contains diverse phenolic compounds, such as flavonoids, as its major biological active constituents. In this study, the pharmacokinetic profiles of eight phenolic compounds were investigated following oral administration of RVE to rats. The eight phenolic compounds were 2,4-dihydroxybenzoic acid, 3,4-dihydroxybenzoic acid, fisetin, fustin, butin, sulfuretin, taxifolin, and garbanzol. The plasma concentrations of the eight compounds were determined by using a liquid chromatography-triple-quadrupole mass spectrometer before and after treatment with β-glucuronidase. When 1.5 g/kg RVE was administered, the eight compounds were all detected in plasma, mainly as conjugated forms. These pharmacokinetic data would be useful for understanding the pharmacological effects of RVE.