Anti-inflammatory maistemonine-class alkaloids of Stemona japonica

Three hitherto undescribed Stemona alkaloids, named stemajapines A–C (1–3), along with six known alkaloids (4–9), were isolated and identified from the roots of Stemona japonica (Blume) Miq. (Stemonaceae). Their structures were established by the analysis of the mass data, NMR spectra, and computational chemistry. Stemjapines A and B were degraded maistemonines without spiro-lactone ring and skeletal methyl from maistemonine. Concurrence of alkaloids 1 and 2 revealed an undescribed way to form diverse Stemona alkaloids. Bioassay results disclosed the anti-inflammatory natural constituents stemjapines A and C with IC50 values of 19.7 and 13.8 µM, respectively, compared to positive control dexamethasone with 11.7 µM. The findings may point out a new direction of Stemona alkaloids inaddition to its traditional antitussive and insecticide activities.