Quantitative determination of diterpenoid alkaloid Fuziline by hydrophilic interaction liquid chromatography (HILIC)–electrospray ionization mass spectrometry and its application to pharmacokinetic study in rats

A rapid, sensitive and specific hydrophilic interaction liquid chromatography coupled to electrospray ionization mass spectrometric (HILIC–MS) method for the quantification of Fuziline (15α-Hydroxyneoline) in rat plasma was developed and validated. After liquid–liquid extraction with ethyl acetate, Fuziline and Guanfu base A (internal standard) were separated with HILIC Chrom Matrix HP amide column (5 μm, 10 cm × 3.0 mm I.D.) with isocratic elution at a flow-rate of 0.2 mL/min. The analytes were detected by using an electrospray positive ionization mass spectrometry in the selected ion monitoring (SIM) mode. A good linear relationship was obtained in the concentration ranging from 1 to 1000 ng/mL (R2 = 0.999) with the lower limit of quantification (LLOQ) at 1 ng/mL and limit of detection (LOD) at 0.5 ng/mL. The average recoveries of Fuziline in plasma at the concentrations of 2, 50, 1000 ng/mL ranged from 68.2 to 69.9%. Intra- and inter-batch relative standard deviations ranged from 1.5 to 3.3% and 2.6 to 8.3%, respectively. Fuziline was stable under different sample storage and processing conditions except three-cycle freeze–thaw treatment at 2 ng/mL. This method was successfully applied to the pharmacokinetic studies in Sprague-Dawley rats. The absolute bioavailability of Fuziline after oral administration 4 mg/kg Fuziline in rats was 21.1 ± 7.0%, with clearance rate at 1745.6 ± 818.1 mL/kg/h, and half-life at about 6.3 ± 2.6 h.