Determination of isobavachalcone in rat plasma by LC-MS/MS and its application to a pharmacokinetic study.

A simple and selective specific high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for determination of isobavachalcone (IBC) in rat plasma was developed. Neobavaisoflavone was used as an internal standard (IS). After protein precipitation with acetonitrile (2:1, v/v), the analyte and IS were separated on a 2.6 μm Kinetex C18 column (100 mm×2.1 mm i.d., Phenomenex) by isocratic elution with acetonitrile:water (60:40, v/v) as the mobile phase at a flow rate of 0.2 mL/min. An electrospray ionization (ESI) source was applied and operated in the negative ion mode; multiple reactions monitoring (MRM) mode was used for quantification, and the target fragment ions m/z 323.0→118.9 for IBC and m/z 321.1→265.0 for the IS were chosen. Good linearity was observed in the concentration range of 3.79-484.5 ng/mL for IBC in rat plasma. The recovery of IBC in plasma was in the range of 81.2-89.8%. Intra-day and inter-day precision were both lower than 10%. This method was suitable for pharmacokinetic studies after oral administration of 80 mg/kg IBC in rats. We also obtained pharmacokinetic parameters and concentration-time profiles for IBC after oral administration of IBC in rats.