Chiral analytical method development and application to pre-clinical pharmacokinetics of pinocembrin

An analytical method enabling the detection and quantification of the individual enantiomers of racemic (+/-) pinocembrin is required to fully characterize its pharmacokinetic disposition. Direct resolution of the enantiomers of pinocembrin was achieved using a novel and simple reversed-phase high-performance liquid chromatography method with electrospray ionization and detection by mass spectrometry in rat serum. A Chiralcel (R) AD-RH column was employed to perform baseline separation with electrospray positive-mode ionization with selected ion monitoring detection. The standard curves were linear from 0.5 to 100 mu g/mL for each enantiomer. The limit of quantification was 0.5 mu g/mL. The assay was applied successfully to stereoselective serum disposition of pinocembrin enantiomers in rats. Pinocembrin enantiomers were detected in serum. Both enantiomers had a serum half-life of similar to 15min in rats. Similar values of volume of distribution between the enantiomers were also observed: 1.76L/kg for S-pinocembrin and 1.79L/kg for R-pinocembrin. Total clearance was 5.527L//h/kg for S-pinocembrin and 5.535L/h/kg for R-pinocembrin, and the area under the curve was 1.821 mu gh/mL for S-pinocembrin and 1.876 mu gh/mL for R-pinocembrin. The large volume of distribution coupled with the short serum half-life suggests extensive distribution of pinocembrin into the tissues. Copyright (c) 2012 John Wiley & Sons, Ltd.