A rapid and sensitive LC-MS/MS method for the determination of osthole in rat plasma: application to pharmacokinetic...

Osthole, a major component isolated from the fruit of Cnidium monnieri (L.) Cusson, has been widely used in traditional Chinese medicine. We developed and validated a rapid and sensitive LC-MS/MS method for the quantification of osthole in rat plasma. Sample preparation involved simple liquid-liquid extraction by ethyl acetate after addition of imperatorin as internal standard (IS). The analyte was separated using a C(18) column with the mobile phase of methanol-0.1% formic acid (80:20, v/v) at a flow rate of 0.4 mL/min. The elutes were detected under positive electrospray ionization in multiple reaction monitoring mode. The method was sensitive with 0.5 ng/mL as the lower limit of detection. Good linearity was obtained over the range of 1.0-500.0 ng/mL. The intra and inter-batch accuracy for osthole in rat plasma samples ranged from 99.5 to 108.1% and the variation was <8.9%. The stability, extraction efficiency and matrix effect were also acceptable. This method was successfully applied to the pharmacokinetic study of osthole in rat after intravenous and oral administration.