Development of enantiospecific and chemoselective methods for the determination of praeruptorin A enantiomers and their metabolites in rat plasma using chiral and achiral LC-MS/MS

Enantioselective pharmacokinetics and metabolism were revealed for (±)-praeruptorin A (PA), the major bioactive component in Peucedani Radix. In the present study, we deal with the development and validation of two enantioselective methods for enantiospecific determination of PA enantiomers (d-PA/l-PA) and their metabolites, cis-khellactone enantiomers (d-CK/l-CK), rat plasma after intravenous or oral treatment using chiral LC-MS/MS, as well as an achiral LC-MS/MS for simultaneous quantitation of the two hydrolyzed products (L1/L2) after incubation of l-PA in fresh rat plasma. AD-RH and Extend-C ₁₈ columns were employed for enantioselective and chemoselective separation, respectively, while the detection was performed on a hybrid triple quadrupole-linear ion trap mass spectrometer with electrospray ionization inlet using a positive selected reaction monitoring mode. The calibration curves of all targeted components showed good linearity (r > 0.992) over the respective concentration ranges (d-PA/l-PA: 1.00-4830 ng mL^-1; d-CK/l-CK: 1.50-1630 ng mL^-1; L1/L2: 1.10-1080 ng mL^-1). The lower limits of quantitation for d-PA/l-PA, d-CK/l-CK and L1/L2 were 1.00/1.00, 1.50/1.50 ng mL^-1 and 1.10/1.10 ng mL^-1, respectively. For high, medium and low concentration levels of all analytes, the overall intra- and inter-day variations were less than 9.71%, recoveries were in the range 87.7-113%, and matrix effects were between 91.1% and 109%. Above all, the chiral and achiral methods that were developed were satisfactory for the determination of d-PA/l-PA, d-CK/l-CK or L1/L2 in rat plasma.