Characterization of the chemical constituents of Croton crassifolius Geisel extract and plasma pharmacokinetics of 6 terpenoids after oral administration by UPLC-Q/TOF-MS.

INTRODUCTION: Croton crassifolius Geisel. (CCG) is a traditional Chinese medicine widely used in South China. It has various pharmacological effects and is often used in treating rheumatoid arthritis and gastric and duodenal ulcers. However, the chemical characteristics and its effective constituents are still scarcely studied. OBJECTIVE: To determine the phytochemical profile of the CCG extract and to investigate the chemical characteristics of terpenoids extracted from rat plasma following oral administration of CCG extract based on UPLC-Q/TOF-MS. Moreover, six terpenoids in CCG were quantified, and in vivo pharmacokinetic behavior after oral CCG extract was further explored. RESULTS: In total, 56 terpenoids were tentatively identified in the CCG extract and 16 terpenoids were detected in rat plasma after oral CCG extract. In addition, the contents of six terpenoids in CCG were clarified. The plasma quantification method of six terpenoids was further established, validated, and confirmed to have good sensitivity and specificity. The six analytes exhibited excellent linearity in respective concentration ranges (r ≥ 0.998). The intra-day and inter-day precisions relative standard deviation (RSD, %) were less than 11.27%, and the accuracies ranged from -7.06% to 9.91%. Stability, extraction recovery, and matrix effect in plasma were within the required limits (RSD < 15%). CONCLUSION: A total of 56 terpenoids were identified in CCG and 16 prototype components in plasma after oral CCG. The validated quantitative method was successfully applied to the simultaneous determination of six major terpenoids in plasma. The pharmacokinetic parameters are clarified, which can guide the clinical application of CCG.

Triterpenoids from the genus Ilex attenuate free fatty acid-induced lipid accumulation in HepG2 cells by regulating lipid metabolism disorder and the AMPK signalling pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Various traditional Chinese medicines from the genus Ilex (Aquifoliaceae) have been reported to have excellent hypolipidaemic effects. Although triterpenoids have been found to be the main active components, the underlying mechanisms have not been clarified. AIM OF THE STUDY: This study aimed to investigate the lipid-lowering effect, structure-activity relationship and action mechanism of triterpenoids from the genus Ilex. MATERIALS AND METHODS: FFA was used to induce HepG2 cells to establish a classical lipid-lowering activity screening model for the activities of 31 triterpenoids, and the contents of intracellular lipids, TC, and TG were measured. Furthermore, the structure-activity relationship was discussed. Mechanistically, UPLC-Q/TOF-MS-based metabolomics and lipidomics studies were performed, and metabolic pathways were analysed to investigate the lipid-lowering mechanism. Moreover, western blotting was performed to analyse the expression of key proteins of lipid metabolism and predict the targets of action. RESULTS: Thirteen triterpenoids significantly reduced intracellular lipid accumulation and decreased the levels of TG and TC. Among them, rotundic acid (RA) showed stronger lipid-lowering activity than the simvastatin-positive group, and structure-activity relationship analysis indicated that the hydroxyl groups at C-3 and C-19, hydroxymethyl groups at C-23, and carboxyl groups at C-28 may be the key groups for biological activity. Twenty-two metabolites in the metabolomics study and 19 metabolites in the lipidomics study were identified. The identified biomarkers were primarily glycerophosphocholine, LysoPCs, PCs, TAGs, LysoPEs, LysoPIs and sphingolipids, which are involved in glycerophospholipid and sphingolipid metabolism. Moreover, western blotting analysis showed that the expression of SREBP-1 and HMGCR decreased, while AMPK and ACC phosphorylation and the expression of CPT1A and CYP7A1 increased in the RA-treated group. CONCLUSION: The results suggested that triterpenoids from the genus Ilex showed significant lipid-lowering effects and that RA may be a novel hypolipidaemic drug candidate. Moreover, the underlying mechanism indicated that RA showed a lipid-lowering effect by regulating glycerophospholipid and sphingolipid metabolism and activating the AMPK pathway.