LC-MS/MS method for simultaneous determination of flavonoids and physalins in rat plasma: Application to pharmacokinetic study after oral administration of Physalis alkekengi var. franchetii (Chinese lantern) extract.

A rapid and sensitive liquid chromatography with tandem mass spectrometry (LC-MS/MS) method was developed and validated for the simultaneous determination of luteolin, luteolin-7-O-β-D-glucopyranoside, physalin A, physalin D and physalin L in rat plasma. Scutellarein and dexamethasone were used as the internal standards (IS). Plasma samples were prepared by liquid-liquid extraction with ethyl acetate. The five constituents were separated on an Acquity UPLC BEH C18 column (100 mm × 2.1 mm, 1.7 μm). A gradient elution procedure was used with acetonitrile (A)-0.1% aqueous formic acid (B). Mass spectrometric detection was performed in negative ion multiple reaction monitoring mode with an electrospray ionization (ESI) source. This method showed good linearity (r(2)  > 0.997) over a concentration range of 2.0-500 ng/mL with a lower limit of quantification of 2.0 ng/mL for all five compounds. The inter- and intra-day accuracy ranged from 91.7 to 104%, and precisions (RSD) were <6.46% for all analytes. The extraction recoveries of all analytes were >85%. This validated method was successfully applied for the first time to the pharmacokinetic study of five ingredients after oral administration of 70% ethanol extract of Chinese lantern in rats.