UPLC-MS/MS Assay for Quantification of Wedelolactone and Demethylwedelolactone in Rat Plasma and the Application to a Preclinical Pharmacokinetic Study

Aims and Objective: Wedelolactone and demethylwedelolactone are the two major coumarin constituents of Herba Ecliptae. The objective of this work was to develop and validate a sensitive, rapid, and robust UPLC-MS/MS method for the simultaneous quantification of wedelolactone and demethylwedelolactone in rat plasma. Materials and Methods: Wedelolactone and demethylwedelolactone were extracted from rat plasma by protein precipitation with acetonitrile. Electrospray ionization in negative mode and selected reaction monitoring (SRM) were used for wedelolactone and demethylwedelolactone at the transitions m/z 312.8 -> 298.0 and m/z 299.1 -> 270.6, respectively. Chromatographic separation was conducted on a Venusil C-18 column (50 mm x 2.1 mm, 5 mu m) with isocratic elution of acetonitrile-0.1% formic acid in water (55:45, v/v) at a flow rate of 0.3 mL/min. A linear range was observed over the concentration range of 0.25-100 ng/mL for wedelolactone and demethylwedelolactone. Results: They reached their maximum plasma concentrations (C-max, 74.9 +/- 13.4 ng/mL for wedelolactone and 41.3 +/- 9.57 ng/mL for demethylwedelolactone) at the peak time (T-max) of 0.633 h and 0.800 h, respectively. The AUC(0-t) value of wedelolactone (260.8 +/- 141.8 ng h/mL) was higher than that of demethylwedelolactone (127.4 +/- 52.7 ng h/mL) by approximately 2-fold, whereas the terminal elimination half-life (t(1/2)) of wedelolactone (2.20 +/- 0.59 h) showed the approximately same as that of demethylwedelolactone (2.08 +/- 0.69 h). Conclusion: Based on full validation according to US FDA guidelines, this UPLC-MS/MS method was successfully applied to a pharmacokinetic study in rats.

Automated summary

In this study, a sensitive UPLC-MS/MS method was developed and validated for the simultaneous quantification of wedelolactone and demethylwedelolactone in rat plasma. The pharmacokinetic parameters showed that wedelolactone had higher AUC and similar t(1/2) compared to demethylwedelolactone.