Isolation and stereochemistry of two new alkaloids from Stemona tuberosa

Two new stenine-type alkaloids, neotuberostemonol () and neotuberostemoninol (), along with the known compound neotuberostemonine (), were isolated from Stemona tuberosa Lour. Their structures were characterized by X-ray crystallography in combination with spectroscopic methods, and their absolute configurations were inferred from the known configuration of tuberostemonine (). In the crystalline state, weak C–H⋯O hydrogen bonds play an important role in the molecular packing of and .