Paeoniflorin (PF, yield up to 5.8% of the dry weight) is the major and the most important component of peony roots. Recent studies demonstrate that PF improves the spatial and memory deficits in rodents and suggest possible utilization of this agent in the treatment of certain types of dementia. The understanding of the metabolism and pharmacokinetics of this agent may provide insights into the mechanism of its effects. Due to the poor absorption from intestine, PF is subjected to the metabolism to give three metabolites, by intestinal bacteria. Paeonimetabolin I (PM-I), the major intestinal bacterial metabolite of PF showed anticonvulsant action. And in the presence of thiol compounds, intestinal bacteria were found capable of transforming PF to more potent anticonvulsant thiopaeonimetabolin-I derivatives. The pharmacokinetics of PF and PM-I were investigated in rats by enzyme immunoassay (EIA), and were dose-dependent. PM-I was not detected in the rat plasma after intravenous (i.v.) administration of PF, and a significant difference in the plasma concentration of PM-I was observed between germ-free and conventional rats. After oral and i.v. administration of PM-I to rats, it was found at high concentrations in the plasmaこの論文は国立情報学研究所の学術雑誌公開支援事業により電子化されまし
