Stemtuberolines A-G, new alkaloids from Stemona tuberosa and their anti-TMV activity.

Three new tuberostemoamide-type alkaloids, stemtuberolines A-C (1-3), four new stenine-type alkaloids, stemtuberolines D-G (4-7), together with five known Stemona alkaloids (8-12), were isolated from the roots of Stemona tuberosa. Their structures were elucidated on the basis of comprehensive spectroscopic data analysis. Stemtuberoline C (3) exhibited significant anti-TMV activity with an inhibition rate of 60.48% at the concentration of 50 μg/mL, while that of ningnamycin, the positive control, was 52.89%.