Cynbungenins A-K, structurally diverse steroids with cytotoxic activity from the roots of Cynanchum bungei Decne.

Chemical investigation of the acid hydrolysate of Cynanchum bungei roots led to the isolation of eleven undescribed steroids, namely cynbungenins A-K (1–11), and seven previously described analogues (12–18). The complete structures of these compounds were elucidated using the comprehensive spectroscopic analyses and reference data. Structurally, compounds 1 and 2 represent the first example of androstane-type steroids found in the Cynanchum plants, and compounds 3 – 6 and 12 are characterized as pregnane-type steroids with a rare 8,14- seco -steroid core. In the cytotoxic activity assay, compound 16 displayed the strongest cytotoxic effect against MCF-7, HCT-116, HeLa, and HepG2 cancer cell lines, with IC 50 values of 9.98 - 16.42 μM, and further research indicated that it induced both apoptosis and cell cycle arrest in the G0/G1 phase in a dose-dependent manner toward HepG2 cells. Eleven undescribed steroids (cynbungenins A-K, 1–11) were isolated from the acid hydrolysate of the roots of Cynanchum bungei. Compound 16 could induce both apoptosis and cell cycle arrest at the G0/G1 phase in a dose-dependent manner toward HepG2 cells. [Display omitted] • Eleven undescribed steroids (1–11) were isolated from Cynanchum bungei roots. • Compounds 1 and 2 represent the first example of androstane-type steroids found in the Cynanchum plants. • Compound 16 induced apoptosis and cell cycle arrest at the G0/G1 phase on HepG2 cells. [ABSTRACT FROM AUTHOR]