An LC-MS/MS method for determination of curculigoside with anti-osteoporotic activity in rat plasma and application to a pharmacokinetic study.

A rapid, simple, selective and sensitive LC-MS/MS method was developed for the determination of curculigoside in rat plasma. The analytical procedure involves extraction of curculigoside and syringin (internal standard, IS) from rat plasma with a one-step extraction method by protein precipitation. The chromatographic resolution was performed on an Agilent XDB-C18 column (4.6 × 50 mm, 5 µm) using an isocratic mobile phase of methanol with 0.1% formic acid and H2 O with 0.1% formic acid (45:55, v/v) at a flow rate of 0.35 mL/min with a total run time of 2.0 min. The assay was achieved under the multiple-reaction monitoring mode using positive electrospray ionization. Method validation was performed according to US Food and Drug Administration guidelines and the results met the acceptance criteria. The calibration curve was linear over 4.00-4000 ng/mL (R = 0.9984) for curculigoside with a lower limit of quantification of 4.00 ng/mL in rat plasma. The intra- and inter-day precisions and accuracies were 3.5-4.6 and 0.7-9.1%, in rat plasma, respectively. The validated LC-MS/MS method was successfully applied to a pharmacokinetic study of curculigoside in rats after a single intravenous and oral administration of 3.2 and 32 mg/kg. The absolute bioavailability of curculigoside after oral administration was 1.27%.