Gracillosides A–F, six new 8,14-seco-pregnane glycosides from Adelostemma gracillimum

Six new 8,14-seco-pregnane glycosides, gracillosides A–F (1–6), were isolated from the roots of Adelostemma gracillimum (Asclepiadaceae). All of them had the same aglycone as gracigenin with a rare 8,14-seco-pregnane type skeleton in nature and possessed an oligosaccharide chain consisting of four to six sugar units at C-3 of the aglycone. Their structures were determined on the basis of detailed spectroscopic analysis and chemical evidence.