New Pregnane Glycosides from Gymnema sylvestre

Abstract

Four new pregnane glycosides 1–4 were isolated from the ethanol extract of the stem of Gymnema sylvestre and named gymsylvestrosides A–D. Hydrolysis of compound 1 under the catalysis of Aspergilus niger β-glucosidase afforded compound 5 (gymsylvestroside E). Their structures were determined by spectroscopic methods such as HRESIMS, 1D and 2D NMR, as well as HMQC-TOCSY experiment. Compounds 1–4 were screened for Saccharomyces cerevisiae α-glucosidase inhibitory activity.

Keywords

• Gymnema sylvestre
• Asclepiadaceae
• pregnane glycosides
• α-glucosidase