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® 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 µg/mL for each enantiomer. The limit of quantification was 0.5 µg/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 ~15 min in rats. Similar values of volume of distribution between the enantiomers were also observed: 1.76 L/kg for S ‐pinocembrin and 1.79 L/kg for R ‐pinocembrin. Total clearance was 5.527 L//h/kg for S ‐pinocembrin and 5.535 L/h/kg for R ‐pinocembrin, and the area under the curve was 1.821 µg h/mL for S ‐pinocembrin and 1.876 µg h/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 © 2012 John Wiley & Sons, Ltd.