Phytochemical investigation of the fruits of Xanthium strumarium and their cytotoxic activity.

Eight pentacyclic triterpenoids including two new ones (1, 2) were isolated from the fruits of Xanthium strumarium. Their structures were elucidated by extensive spectroscopic analysis. All isolates were evaluated for in vitro cytotoxic activity on HepG2, A549, HCT116 and SW480 cancer cells. Among them, the new compound 2 was found to exhibit significant cytotoxic activity on A549, HCT116 and SW480 cancer cells with IC50 values of 9.68, 4.27 and 7.58 μM, respectively. Further, 2 was selected for cell cycle analysis and results revealed that 2 could cause HCT116 cell cycle arrest in G1 phase. In addition, Annexin V-FITC/PI staining assay showed that 2 could induce the death of HCT116 cells.