Quantification of pinosylvin in rat plasma by liquid chromatography–tandem mass spectrometry: Application to a pre-clinical pharmacokinetic study

Pinosylvin (trans-3,5-dihydroxystilbene), a naturally occurring analogue of resveratrol (trans-3,5,4′-trihydoxystilbene), exhibited various beneficial pharmacological activities in pre-clinical studies. To further probe its potential medicinal application, a sensitive liquid chromatography–tandem mass spectrometry method (LC–MS/MS) was developed and validated for the quantification of pinosylvin in rat plasma. A simple protein precipitation procedure was used for plasma cleanup before analysis by LC–MS/MS with electrospray ionisation and multiple reaction monitoring in its negative ion mode. This LC–MS/MS method demonstrated good selectivity, accuracy (intra- and inter-day analytical recovery within 100 ± 7.7%), precision (intra- and inter-day coefficient of variation < 12.0%) and sensitivity (lower limit of detection = 1.0 ng/mL), with excellent linearity (R2 > 0.99) over the range of 1–1000 ng/mL. The pharmacokinetic profiles of pinosylvin were subsequently assessed in Sprague–Dawley rats. Following intravenous administration (5 or 10 mg/kg), plasma levels of pinosylvin declined rapidly with a short half-life (t1/2 < 10 min). Upon oral administration at 15 mg/kg, pinosylvin could not be quantified in plasma (<1 ng/mL) while dose-escalation to 50 mg/kg led to a low and erratic plasma exposure with very poor estimated oral bioavailability (F < 1%). The short half-life and limited systemic exposure of pinosylvin prompt caution in its therapeutic application and it warrants exploration in developing pinosylvin pro-drug.