New pregnane glycosides from the roots of Cynanchum otophyllum

Six new pregnane glycosides with an acyl at C-12 and a straight sugar chain at C-3, namely otophyllosides H–M (1–6), were isolated from the roots of Cynanchum otophyllum (Asclepiadaceae) collected from Eryuan County in Yunnan province of China. Their structures were characterized to be qingyangshengenin 3-O-β-d-glucopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 4)-β-d-cymaropyranosyl-(1 → 4)-β-d-oleandropyranosyl-(1 → 4)-β-d-digitoxopyranoside (1), qingyangshengenin 3-O-β-d-glucopyranosyl-(1 → 4)-β-d-oleandropyranosyl-(1 → 4)-β-d-cymaropyranosyl-(1 → 4)-β-d-digitoxopyranoside (2), qingyangshengenin 3-O-β-d-glucopyranosyl-(1 → 4)-β-d-cymaropyranosyl-(1 → 4)-β-d-oleandropyranosyl-(1 → 4)-β-d-cymaropyranosyl-(1 → 4)-β-d-digitoxopyranoside (3), qingyangshengenin 3-O-β-d-glucopyranosyl-(1 → 4)-β-d-thevetopyranosyl-(1 → 4)-β-d-cymaropyranosyl-(1 → 4)-β-d-digitoxopyranoside (4), caudatin 3-O-β-d-glucopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 4)-β-d-cymaropyranosyl-(1 → 4)-β-d-oleandropyranosyl-(1 → 4)-β-d-cymaropyranoside (5), caudatin 3-O-β-d-glucopyranosyl-(1 → 4)-β-d-cymaropyranosyl-(1 → 4)-β-d-oleandropyranosyl-(1 → 4)-β-d-cymaropyranosyl-(1 → 4)-β-d-cymaropyranoside (6), respectively, on the basis of detailed spectroscopic analysis and chemical method.