Determination of chamaechromone in rat plasma by liquid chromatography–tandem mass spectrometry: Application to pharmacokinetic study

A rapid, simple and accurate method was developed for the determination of chamaechromone in rat plasma using liquid chromatography tandem mass spectrometry (LC–MS–MS). Rosuvastatin was used as the internal standard. The plasma samples were extracted by liquid–liquid extraction with ethyl acetate. Chromatographic separation was performed on Xbridge™ C18 column (2.1 mm × 50 mm, 3.5 μm) with linear gradient elution using water and methanol, both of which were acidified with 0.1% aqueous formic acid. The flow rate was 0.4 mL/min and the total run time was 6 min. Detection was performed on a triple-quadrupole tandem mass spectrometer using positive ion mode electrospray ionization (ESI) in the multiple reaction monitoring (MRM) mode. The MS/MS ion transitions monitored were m/z 543.3 → 198.9 and 481.9 → 258.3 for chamaechromone and rosuvastatin, respectively. Good linearity was observed over the concentration range of 8–6400 ng/mL in 0.1 mL of rat plasma. The lowest concentration (8 ng/mL) in the calibration curve was estimated as LLOQ with both deviation of accuracy and RSD of precision <20% (n = 6). Intra-assay and inter-assay variability were less than 11% in plasma. This method was successfully applied to a pharmacokinetic study of chamaechromone in rats after intravenous (5 mg/kg) and oral (100 mg/kg) administration. Following oral administration the concentration–time curve of chamaechromone exhibited a biphasic absorption profile. The maximum mean concentration in plasma (Cmax, 795.9 ± 14.6 ng/L) was achieved at 11.3 ± 0.8 h (Tmax) and the area under curve (AUC0–60) was 6976.7 ± 1026.9 ng h/L. After single intravenously administration of chamaechromone, the essential pharmacokinetic parameters Cmax, AUC0–48 were 4300.7 ± 113.6 ng/L and 3672.1 ± 225.4 ng h/L, respectively. The result showed that the compound was poorly absorbed with an absolute bioavailability being approximately 8.9%.