Three New Pregnanes Isolated from the Cynanchum auriculatum

Three new compounds named cynansteroid A (1), cynansteroid B (2) and cynansteroid C (3), together with nine known C₂₁ -steroidal pregnane sapogenins (4-12) were isolated from the hydrolytic extract of the roots of Cynanchum auriculatum. The structures of cynansteroid A-C (1-3) were ascertained via the detailed analysis of the HR-ESI-MS, 1D and 2D NMR, and the calculated and experimental ECD data of cynansteroid B (2). Compound 11 displayed moderate inhibitory activity toward Verticillium dahliae Kleb (IC₅₀ =37.15 μM), furthermore, compounds 11 and 12 showed significant inhibitory activity against Phomopsis sp. (IC₅₀ =16.49 μM and 17.62 μM, respectively).