Stemospironine, a new insecticidal alkaloid of Stemona japonica Miq. isolation, structural determination and activity.

A new alkaloid named stemospironine (I) was isolated together with stemofoline (II) as the main insecticidal constituents of leaves and stems of Stemona japonica Miq. The absolute stereostructure of I has been determined by X-ray crystallographic analysis. Stemofoline (II) showed a much stronger activity than I against silkworm larvae (Bombyx moni L.) by oral administration.