Steroidal components from the roots and rhizomes of Helleborus thibetanus

Three new steroidal components hellebogenins A and B (1 – 2) and thibetanoside I (3) together with four know ones (4 – 7) were isolated from the roots and rhizomes of Helleborus thibetanus. Their structures were elucidated by chemical methods and spectroscopic analysis. Among them, compound 1 possessed three double bonds at the positions of 1(2), 5(6) and 25(27), while compound 2 had an α, β unsaturated ketone carbonyl on the A ring. In addition, compounds 1 and 2 showed cytotoxic activities against HCT116 cells with IC50 values of 42.0 ± 1.3 μM and 67.3 ± 1.5 μM, respectively.