(+)-Angchibangkine, a New Type of Bisbenzylisoquinoline Alkaloid, and Other Dimers from Pachygone dasycarpa

Analysis of the alkaloidal fraction of the stem bark extract of Pachygone dasycarpa (Menispermaceae) resulted in the isolation of 10 known bisbenzylisoquinolines, (+)-tetrandrine, (+)-penduline, (+)-fangchinoline, (+)-atherospermoline, (+)-N-methyl-7-O-demethylpeinamine, (+)-daphnoline, (4-)-isotrilobine (1), (+)-cocsuline (2), (+)-tricordatine (3), (+)-2'-norcocsuline, and the new alkaloid (+)-12-O-methyltricordatine (4). The last bisbenzylisoquinoline alkaloid isolated, (+)-angchibangkine (5), is the first member of this alkaloid class found to possess three diphenyl ether bridges in the 7-6',8-7', and 11-12' positions. Structure elucidation of these alkaloids and of (+)-O-methylangchibangkine (6) was achieved by analysis of spectral data. Compounds 4-6 show antiplasmodial activity against Plasmodium falciparum.