Pharmacokinetics, bioavailability, excretion, and metabolic analysis of Schisanlactone E, a bioactive ingredient from Kadsura heteroclita (Roxb) Craib, in rats by UHPLC-MS/MS and UHPLC-Q-Orbitrap HRMS.

Schisanlactone E (SE) is a bioactive ingredient extracted from the stem of Kadsura heteroclita (Roxb) Craib. SE has various pharmacological activity such as anti-tumor and anti-leukemia effects. However, its absorption, distribution, metabolism, and excretion have rarely been examined. In this study, new quali-quantitative analytical methods were developed for metabolic and pharmacokinetic studies of SE in rats. A UHPLC-MS/MS method was developed to determine SE in rat plasma, urine, and feces. Samples were precipitated with methanol and analyzed in multiple reaction monitoring mode. The established method was validated and applied to the pharmacokinetics, bioavailability, and excretion analysis of SE after oral (6 mg/kg) or intravenous (2 mg/kg) administration. The absolute oral bioavailability of SE was approximately 79.3%. After oral administration, SE was mainly excreted via feces with a rate of 41.7% for 48 h. SE could not be detected in urine. Furthermore, a UHPLC-Q-Orbitrap HRMS method was developed for the metabolite screening of SE in rat plasma, urine, and feces. Metabolites were extracted by solid phase extraction and analyzed with full MS/dd-MS² scan mode. As a result, 15 metabolites including 11 phase I and 4 phase II metabolites were identified by a three-step analytical strategy. The carboxyl group, the five membered ring, and the six membered α,β-unsaturated lactone ring of SE could be predicted as the main metabolic sites. This study provides comprehensive insights into the pharmacokinetic and metabolic profiles of SE, and would be valuable for future development and utilization of SE and Kadsura heteroclita.