14,15-Secopregnane-Type Glycosides with 5α:9α-Peroxy and Δ6,8(14)-diene Linkages from the Roots of Cynanchum stauntonii

Three new 14,15-secopregnane-type glycosides, stauntosides UA, UA1, and UA2, were isolated from the roots of Cynanchum stauntonii. The three compounds share the first reported and same basic structural features of 3β-hydroxy-14:16,15:20,18:20-triepoxy-5α:9α-peroxy-14,15-secopregnane-6,8(14)-diene named as stauntogenin G as the aglycones. The structures of the new compounds were characterized on the basis of extensive spectroscopic analyses, mainly 1D and 2D NMR and MS methods and chemical analysis. The isolation and identification of the new compounds graced the structural diversity of pregnane-type steroids from C. stauntonii.