SELECTIVE ANTIPROTOZOAL ACTIVITY OF SOME STRYCHNOS ALKALOIDS

The in vitro activities of 20 Strychnos alkaloids have been determined against three species of protozoa and the active compounds were then assessed for in vitro cytotoxic activity using KB cells. 3',4'-dihydro usambarensine was the most active against Plasmodium falciparum, and w as relatively nontoxic to KB cells (cytotoxic/antiprotozoal ratio, 147 4). Usambarensine displayed the most selectivity against Entamoeba his tolytica while 3',4'-dihydrousambarensine was the most selective compo und against Giardia intestinalis although the cytotoxicl antiprotozoal ratios (20.4 and 6.6 respectively) were less favourable than the abov e.