Two new alkaloids from the rhizome of Polygonatum sibiricum.

Two new alkaloids named polygonatine A (1) and polygonatine B (2) have been isolated from the rhizome of Polygonatum sibiricum Redoute (Liliaceae). By spectral data (IR, UV, MS, 1D and 2D NMR) and chemical evidence, their structures were elucidated as 3-hydroxymethyl-5,6,7,8-tetrahydroindolizin-8-one (1) and 3-ethoxymethyl-5,6,7,8-tetrahydroindolizin-8-one (2).