Simultaneous determination of three sesquiterpene lactones from Herba Inula extract in rat plasma by LC/MS/MS and its application to pharmacokinetic study

A rapid and sensitive liquid chromatography–tandem mass spectrometry method has been developed and validated for the determination of 1-acetoxy-6α-hydroxyeriolanolide, 1β-hydroxyalantolactone and ivangustin from Herba Inula extract in rat plasma. Plasma samples were pretreated by protein precipitation with methanol. Chromatographic separation was accomplished on a TOSOH TSKgel ODS column with mobile phase consisting of methanol and 0.3% formic acid (80:20, v/v). The detection was carried out by multiple-reaction monitoring mode under positive electrospray ionization. The quantification was performed using the transitions of m/z 309.1/185.0 for 1-acetoxy-6α-hydroxyeriolanolide, m/z 249.0/231.1 for 1β-hydroxyalantolactone and ivangustin and m/z 285.0/193.0 for diazepam, respectively. Calibration curves were linear over the concentration range of 4–800 ng/mL for 1-acetoxy-6α-hydroxyeriolanolide, 8–500 ng/mL for 1β-hydroxyalantolactone and ivangustin. The limit of detection (LOD) was 1 ng/mL for 1-acetoxy-6α-hydroxyeriolanolide, 1.6 ng/mL for 1β-hydroxyalantolactone and ivangustin (S/N = 3). The intra-day and inter-day precisions (RSD%) for the three compounds were less than 7.8% and 8.6%, and the accuracy (RE%) ranged from −4.6 to 6.8%. The method was successfully applied to pharmacokinetic studies of the three sesquiterpene lactones after oral administration of 300 mg/kg Herba Inula extract to rats, the t1/2 of 1-acetoxy-6α-hydroxyeriolanolide, 1β-hydroxyalantolactone and ivangustin was 9.65 ± 1.43, 14.88 ± 0.82 and 13.93 ± 2.74 (h). The AUC(0−t) of 1-acetoxy-6α-hydroxyeriolanolide, 1β-hydroxyalantolactone and ivangustin was 1102.46 ± 247.04, 808.92 ± 117.53 and 990.35 ± 275.49 (ng h/mL), respectively.

► We develop LC/MS/MS method for simultaneous determination of three sesquiterpene lactones in rat plasma for the first time.
► Sensitivity, recovery and reproducibility of the developed method are good.
► There are few studies on pharmacokinetics of sesquiterpene lactones, which have shown good biological activities. Therefore, it is suggested that more attentions should be paid to the research on these compounds in vivo.