Structure elucidation of antiproliferative bisbenzylisoquinoline alkaloids from Anisocycla grandidieri from the Madagascar dry forest

Antiproliferative bioassay‐guided fractionation of the ethanol extract of the stems of Anisocycla grandidieri led to the isolation of the known alkaloids stebisimine (1), (+)‐1,2‐dehydrotelobine (2), (+)‐2'‐norcocsuline (3) and puetogaline B (4). Herein, we report the full NMR assignments of all compounds and the X‐ray crystallography of single crystals of compounds 1 and 3. Compounds 2 and 3 showed moderate antiproliferative activity against the A2780 human ovarian cancer cell line with IC₅₀ values of 4.1 ± 0.3 and 2.7 ± 0.3 μM, respectively, and they also displayed selective activity toward the H460 (large cell lung cancer), MCF‐7 (breast ductal carcinoma), and UACC‐257 (melanoma) cell lines. Copyright © 2013 John Wiley & Sons, Ltd.