A new morphinandienone alkaloid from the stems of Fissistigma tungfangense.

A new morphinandienone alkaloid, fissistigmine A (1), together with three known alkaloids (2-4), were isolated and identified from the stems of Fissistigma tungfangense. Among them, fissistigmine A (1) represents the first example of a novel naturally occurring morphinandienone alkaloid with a unique cleavage of the C-9-N-17 bond. All isolated compounds were evaluated for their anti-rheumatoid arthritis activities via examining their anti-proliferative effects on synoviocytes in vitro. Compound 1 exhibited inhibitory effect on the proliferation of synoviocytes with an IC ₅₀ value of 114.6 ± 2.2 μM.