Pharmacokinetics, Tissue Distribution, and Tentative Metabolite Identification of Sauchinone in Mice by Microsampling and HPLC-MS/MS Methods

: Sauchinone, a biologically active lignan found in Saururus chinensis (Saururaceae), exerts various biological activities against jaundice, inflammatory disease, hepatic steatosis, and oxidative injury. Despite its diverse applications, there exists some information about sauchinone's pharmacokinetics but its tissue distribution, metabolism, and tentative metabolites have not been reported yet. Thus we investigated the pharmacokinetics of sauchinone in mice using microsampling and HPLC-MS/MS methods. Sauchinone presented linear pharmacokinetics at intravenous doses 7.5-20 mg/kg and oral doses 20-500 mg/kg. However, the metabolism of sauchinone was saturated and this agent presented nonlinear pharmacokinetics at 50 mg/kg in the intravenous study. At sauchinone 20 mg/kg the F of sauchinone was 7.76% of the oral dose despite that 77.9% of sauchinone was absorbed. This might be due to extensive metabolism of sauchinone in S9 fractions of liver and small intestine. Tentative metabolites of sauchinone by oxidation, dioxidation, methylation, demethylation, dehydrogenation, or bis-glucuronide conjugation were detected in plasma and S9 fractions of liver, intestine, and kidney. The distribution of sauchinone was considerably high (tissue-to-plasma (T/P) ratios, >1) in liver, small intestine, kidney, lung, muscle, fat, or mesentery after intravenous and oral administration and in stomach and large intestine only after oral administration. The protein binding value of sauchinone was 53.0%. These pharmacokinetic data of sauchinone provide an important basis for preclinical applications and experimental methods can be adjusted to evaluate the pharmacokinetics of natural products in mice.