Cytotoxic and antimalarial alkaloids from the tubers of Stephania pierrei.

Biological evaluation of extracts prepared from the tubers of Stephania pierrei revealed cytotoxic and antimalarial activity. During the course of separation, two new aporphine alkaloids, (-)-asimilobine-2-O-beta-D-glucoside [2] and (-)-nordicentrine [8], in addition to twenty-one known isoquinoline alkaloids, were isolated. Each isolate was assessed for cytotoxic and antimalarial activities. It was found that the cytotoxicity of S. pierrei was mainly due to the presence of the aporphine alkaloids containing the 1,2-methylenedioxy group 3-10, whereas the antimalarial activity was attributed to the nonquaternary aporphine alkaloids 1, 3-10 and the tetrahydroprotoberberines possessing a phenolic functionality, 13-15, 18. None of the isolates showed a degree of selectivity comparable to that of antimalarial drugs such as chloroquine, quinine, mefloquine, and artemisinin. Comparison of the alkaloid content of S. pierrei and Stephania erecta strongly suggested separate identities for the two plants.