A new C21 steroidal glycoside from Cynanchum inamoenum (Maxim.) Loes

A new C21 steroidal glycoside, 5β,6β-epoxy-glaucogenin C-3-O-β-d-glucopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 4)-β-d-cymaropyranosyl-(1 → 4)-β-d-oleandropyranosyl-(1 → 4)-β-d-oleandropyranoside, named inamoside D (1), was isolated from the MeOH extract of the roots of Cynanchum inamoenum (Maxim.) Loes (Asclepiadaceae). In addition, five known compounds, including 7-demethoxytylophorine (2), dehydrodiconiferyl alcohol γ′-O-β-d-glucopyranoside (3), β-d-fructofuranosyl-(2 → 1)-α-d-(6-O-sinapoyl)-glucopyranoside (4), neohancoside C (5), and cuchiloside (6), have also been isolated. The structure of 1 was determined by 1D- and 2D-NMR spectroscopies. All the compounds were isolated from this plant for the first time.