Vier neue Pregnanglycoside aus Gongronema latifolium (Asclepiadaceae)

Four New Pregnane Glycosides from Gongronema latifolium (Asclepiadaceae) Four so far unknown pregnane biosides have been isolated from the chloroform extract of the leaves of Gongronema latifolium Benth. et Hook. (Asclepiadaceae). From one‐ and twodimensional NMR experiments (NOE difference spectroscopy, ROESY, H,H‐COSY, C,H‐COSY, HMBC) their structures have been established as 3‐O‐[6‐deoxy‐3‐O‐methyl‐β‐D‐allopyranosyl‐(1→4)‐β‐D‐canaropyranosyl]‐17β‐marsdenin (1a), 3‐O‐[6‐deoxy‐3‐O‐methyl‐β‐D‐allopyranosyl‐(1→4)‐β‐D‐oleandropyranosyl]‐17β‐marsdenin (1b), 12‐O‐acetyl‐3‐O‐[6‐deoxy‐3‐O‐methyl‐β‐D‐allopyranosyl‐(1→4)‐β‐D‐canaropyranosyl]‐17β‐marsdenin (1c) and 11‐O‐acetyl‐3‐O‐[6‐deoxy‐3‐O‐methyl‐β‐D‐allopyranosyl‐(1→4)‐β‐D‐canaropyranosyl]‐17β‐marsdenin (1d).