Barrigenol triterpenes from the husks of Xanthoceras sorbifolia Bunge and their antitumor activities

Abstract

Barrigenol-like triterpenoids containing angeloyl residues in their structures are unusual natural products. To discover the chemical constituents responsible for the antitumor activity of Xanthoceras sorbifolia Bunge, the present study was carried out using the husk of this crop. Ten angeloyl barrigenol triterpenoids, including seven new (1–7) and three known compounds (8–10), were isolated from the active fraction via the bioassay-guided method. The structures of the compounds were established on the basis of spectral analysis, especially according to the data afforded by two digital-NMR and high-resolution mass spectra experiments. Compounds 1–10 exhibited varying degrees of cytotoxicity toward the human hepatoma cell line (HepG2), the human colorectal cancer cell line (HCT116) and the human glioma cell line (U87-MG). New compounds 3, 6, and 7 and known compounds 8, and 10 showed inhibitory activities similar to those of the positive control (doxorubicin hydrochloride). Cell cycle and apoptosis analysis of compound 8 revealed that it could suppress U87-MG cell proliferation by inducing apoptosis in the early period of exposure and then promote arrest at the G0/G1 phase.