LC-MS/MS Determination and Pharmacokinetic Study of Pedunculoside in Rat Plasma after Oral Administration of Pedunculoside and Ilex rotunda Extract

Ilex rotunda is widely used to treat many disorders as a traditional Chinese medicine (TCM) containing 4%–5% pedunculoside (PDC). A rapid, selective, and sensitive liquid chromatography-tandem mass spectrometry method (LC-MS/MS) was developed and validated to determine PDC in rat plasma by using 3β,19α-dihydroxyurs-12-en-28-oic acid 28-β-D-glucopyranosyl ester (DEOG) as an internal standard. The analytes were extracted by protein precipitation and eluted on a C(18) chromatography column using a mobile phase of methanol–H(2)O (70:30, v/v) delivered at a flow rate of 0.6 mL/min. Detection was performed using positive ion electrospray ionization in multiple reaction monitoring modes. The assay was linear over the concentration range of 0.60 ng/mL to 200 ng/mL, with a quantification limit of 0.60 ng/mL. Intra-day and inter-day precisions (%RSD) ranged from 2.12 to 9.51 for PDC, whereas the accuracy was within −7.83%~9.40%. The validated method was successfully applied to the pharmacokinetic study of PDC in rat plasma after oral administration of pure PDC and Ilex rotunda extract (IRE). Pharmacokinetic parameters of PDC in IRE, such as C(max), AUC(0–t), AUC(0–∞), t(1/2z)(,) and CL(z)/F, statistically differed from those of the pure monomer (p < 0.01). However, T(max) and MRT showed no significant differences between the two groups. Results suggested that other coexisting components in IRE may decrease the absorption of PDC. Compound-compound interactions between PDC and other herbal extract components can alter the pharmacokinetic behavior of PDC. The study will be helpful in providing references for understanding the action mechanism and clinical application of Ilex rotunda.