Alkaloids from the stems of Merr. inhibit the proliferation of synoviocytes.

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