Pharmacokinetics and Tissue Distribution Study of Daphnoretin in Ethanol Extract from the Roots of Wikstroemia Indica in Rats by a Validated UPLC-MS/MS Method

Background: Daphnoretin, as a known bicoumarin compound that contained various pharmacological activities, was isolated from Wikstroemia indica C.A. Mey (RWI). Objective: The study aims to investigate the pharmacokinetic characteristics of daphnoretin from RWI ethanol extracts in rat plasma and to determine daphnetin in rat plasma and various tissues by a rapid, reliable and sensitive ultra high performance liquid chromatography with tandem mass spectrometry method. Methods: The UPLC-MS/MS method was established. Daphnoretin and IS (buspirone) were chromatographed on an agilent Zorbax XDB-C18 column (2.1 mm × 50 mm, 3.5 μm), and Gradient elution of acetonitrile-0.15% formic acid in aqueous solution. Quantification was performed using electrospray ionization in positive ion multiple reaction monitoring mode of the transitions m/z 353.1→179.1 for daphnoretin and m/z 386.3→122.3 for IS. Results: Good linearity between 5-10000 ng/mL for cyperidin in plasma and tissue samples (r ≥ 0.99) was resulted. The accuracies of plasma and tissue homogenates ranged from-3.31% to 9.00%, and the precision was less than 5.78%. After that, the validated method was successfully applied to the pharmacokinetics and tissue distribution study of daphnoretin after oral administration of ethanol extract from the roots of RWI to rats. Conclusion: Daphnoretin was well absorbed in the systemic circulation after oral administration and was widely distributed in tissues, with the highest concentration in lung tissue. This study is beneficial to the development and utilization of RWI and provides a reasonable reference for its clinical administration.