Determination of Schaftoside and Isoschaftoside in Rat Plasma Utilizing UPLC-MS/MS

To evaluate the pharmacokinetics, absolute bioavailability, and plasma concentrations of schaftoside and isoschaftoside in rats, an UPLC-MS/MS method was employed. For sample preparation, plasma proteins were precipitated using chilled methanol. The separation was achieved on a UPLC HSS T3 column with a mobile phase consisting of methanol and water (with 0.1% formic acid in water), at a flow rate of 0.4 mL/min. Detection was performed using electrospray ionization (ESI) in positive ion mode, coupled with multiple reaction monitoring (MRM) for quantitative analysis. Rats received oral doses of schaftoside (1 mg/kg) and isoschaftoside (5 mg/kg), and the pharmacokinetic profiles of both compounds were compared. The calibration curve for the method demonstrated excellent linearity within the concentration range of 1–2000 ng/mL, with correlation coefficients (r values) exceeding 0.99. Following intravenous and oral administration, significant differences were observed in the AUC_(0–t) between schaftoside and isoschaftoside, whereas their half-lives (t_1/2) remained comparable. The absolute bioavailability of schaftoside and isoschaftoside in rat plasma was determined to be 0.95% and 0.22%, respectively.