Two new aporphine-derived alkaloids, aporaloids C and D (1 and 2), along with eight known biogenetically related alkaloids (3-10) were isolated from the stems of Fissistigma maclurei Merr. Their structures were elucidated by detailed analysis of NMR, HRESIMS, MS, IR, UV and Optical rotations data. Compounds 1 and 2 represent a rare example of N-methylol aporphine-derived alkaloids from natural sources. The inhibitory effect of all compounds on the proliferation of primary synovial cells was evaluated. Compound 3 showed potent inhibitory effect on the proliferation of synoviocytes with an IC50 value of 4.8 μM. Compounds 1, 2, 6-9 and 10 exhibited moderate inhibitory activity on synoviocytes, with IC50 values of 36.8, 37.1, 31.2 μM, 32.5, 36.3, 36.8 and 18.2 μM, respectively.
Keywords: Annonaceae; Fissistigma maclurei Merr; aporphine-derived alkaloids; synoviocytes.