Determination and pharmacokinetic study of guaiol in rat plasma by gas chromatography-mass spectrometry with selected ion monitoring.

Guaiol has been used for thousands of years as a traditional Uygur medicine and is the primary active component found in Ferula ferulaeoides (Steud.) Korov (F. ferulaeoides). In our present study, a rapid, selective, and sensitive method of monitoring selected ions was established based on gas chromatography-mass spectrometry. This method was optimized for the quantification and pharmacokinetic analysis of guaiol in rat plasma following oral administration of chloroform extract from Ferula ferulaeoides. Plasma was extracted using liquid-liquid extraction with ethyl acetate and was analyzed on a HP-5MS column (30 m × 250 μm × 0.25 μm) with a mass selective detector. Detection was carried out under selected ion monitoring mode, and three selected ion monitoring ions (m/z 59.1, 107.1, and 161.1 for guaiol) were used for the quantitative determination of that under investigation. The assay demonstrated excellent linearity in the range of 1-200 ng/mL (r = 0.9993, n = 8) in the case of guaiol measured in rat plasma. The limit of detection and the limit of quantification for guaiol in rat plasma were found to be 0.25 ng/mL and 1 ng/mL, respectively. Intra-day and inter-day precisions were expressed as the relative standard deviation for the method and were in the range of 97.49%-106.16% and 97.04%-105.91%, respectively. Extraction efficiencies were all determined to be >90%, and recoveries were ranged from 91.25% to 96.24%. This method has been successfully applied for the pharmacokinetic evaluation of chloroform extract isolated from F. ferulaeoides following a single oral administration dose (157.5 mg/kg) in rats. The guaiol pharmacokinetic study demonstrated that the half-life of guaiol was 9.18 ± 3.75 h, the mean residence time was 9.07 ± 3.86 h, the maximum guaiol concentration in the plasma was 28.63 ± 6.82 ng/mL, and the maximum time guaiol was in the plasma was 0.50 h.