Simultaneous pharmacokinetics and stability studies of physalins in rat plasma and intestinal bacteria culture media using liquid chromatography with mass spectrometry.

Physalins are the major steroidal constituent of Physalis plants and display a range of biological activities. For this study, a rapid and sensitive high-performance liquid chromatography with triple quadrupole mass spectrometry method was developed for the simultaneous quantification of six physalins. Specifically, it was for the quantification of physalin A, physalin B, physalin D, physalin G, 4,7-didehydroneophysalin B, and isophysalin B in rat plasma and rat intestinal bacteria. After a solid-phase extraction, analytes and internal standards (prednisolone) were separated on a Shield reverse-phase C18 column (measuring 3 mm × 150 mm with an internal diameter of 3.5 μm) and determined using multiple reactions in a monitoring mode with a positive-ion electrospray ionization source. The mobile phase was a mixture of 0.1% formic acid in water (A) and acetonitrile (B) and was used at a flow rate of 0.6 mL/min. The intra- and interday precisions were within 15% with accuracies ranging from 86.2 to 114%. The method was validated and successfully applied to pharmacokinetics and stability studies of six physalins in rat plasma and rat intestinal bacteria, respectively. The results showed that physalin B and isophysalin B could not be absorbed by rats, and rat intestinal bacteria could quickly transform physalins.