TRADITIONAL MEDICINAL-PLANTS OF THAILAND .20. CYTOTOXIC AND ANTIMALARIAL BISBENZYLISOQUINOLINE ALKALOIDS FROM STEPHANIA-ERECTA

(+)-2-N-Methyltelobine [1], a new alkaloid, together with twelve known bisbenzylisoquinolines, was isolated from the tubers of Stephania erecta. The structure determination and the complete H-1- and unambiguous C-13-nmr assignments of 1 were obtained through extensive use of several ID and 2D nmr techniques. All alkaloids inhibited the growth of cultured Plasmodium falciparum strains D-6 and W-2 and displayed nonselective cytotoxicity with a battery of cultured mammalian cells. These data were used for the calculation of selectivity indices. Relative to known antimalarial agents, these bisbelkzylisoquinoline alkaloids do not appear to be promising clinical candidates at the present time.