Simultaneous determination of corosolic acid and euscaphic acid in the plasma of normal and diabetic rat after oral administration of extract of Potentilla discolor Bunge by high-performance liquid chromatography/electrospray ionization mass spectrometry.

Potentilla discolor Bunge has been used for diabetes in China for a long time. Corosolic acid (CA) and euscaphic acid (EA), with significant anti-diabetic activity, are two major triterpenoids in P. discolor. In this study, a specific, sensitive and convenient LC-MS method has been developed for simultaneous determination of CA and EA in the plasma of normal and diabetic rats after oral administration of the extract of P. discolor. The chromatographic separation was achieved using an Alltima C18 column (53 × 7.0 mm, i.d., 3 µm) with a mobile phase composed of 0.1% formic acid water and 0.1% formic acid acetonitrile at a flow rate of 1.0 mL/min. The detection was performed by MS with electrospray ionization interface in negative selected ion monitoring mode. All the validation data, such as specificity, linearity (r(2)  > 0.9991 within 0.025-10.0 µg/mL), lower limit of quantitation (2.5 ng/mL), precision (intra- and inter-day <14.7%), accuracy (<15.0%), recovery (85.7-110.8%) and stability were determined and all of them were within the required limits. This method was successfully applied for the evaluation of the pharmacokinetic behaviors of these two compounds in the plasma of normal and diabetic rats.