粉背薯蓣(Dioscorea collettii Hook.var.hypoglauca(Polibin)Pei et Ting,主要产于华东地区。1984年作者曾从江西庐山的粉背薯蓣根茎中,分到两个新皂甙(A和C)。本文报道另外两个皂甙(B和E)的分离鉴定。根据理化性质及红外、质谱、碳谱测定,推断皂甙B的结构式为薯蓣皂甙元-3-O-[β-D-葡萄吡喃糖(1→3)-O-a-L-鼠李吡喃糖(1→ Dioscorea collettii Hook. var. hypoglauca (Polibin) Pei et Ting, is mainly produced in East China. In 1984, the author had divided two new saponins (A and C) from the root of Dioscorea nipponica in Jiangxi Lushan. In this paper, the separation and identification of two other saponins (B and E) are reported.According to physicochemical properties and infrared, mass spectrometry, and carbon spectrometry, it is concluded that the structural formula of saponin B is diosgenin-3-O-[β-D-pyranopyranose. (1→3)-OaL-Rhamnopyranose (1→