Abstract:Dresgenin, a new aglycone, was isolated from the rhizome of Dregea sinensis var. corrugata (Schneid) Tsiang et P. T. Li (Asclepiadaceae). On the basis of spectroscopic analysis and chemical reactions, the structure was established as C/D cis 5α-H, 3β, 8β, 14β, 17β-tetrahydroxyl-12-β-O-benzoyl-20-hydrooxyl-pregnane. The mass spectrum suggests the presence of benzoyl group. Alkaline hydrolysis of (Ⅰ) with 5% methanolic potassium hydroxide yields deacyldresgenin (Ⅱ) and benzoic acid.