In vitro activity of mefloquine and its enantiomers against Plasmodium falciparum

The in vitro activity of rac-mefloquine hydrochloride and its pure enantiomers was tested against a chloroquine-resistant (PF.IBS2) strain of Plasmodium falciparum . The parasite isolated from Iranian patients was cultured in vitro by the candle jar method described by Tranger and Jensen and was exposed to the racemic mefloquine or its enantiomers over the concentration range of 10-9 to 10-4 M. Neither rac-mefloquine nor the enantiomers showed antiparasitic activity at 10-9 M. The (+)-mefloquine was more potent than the (-)-mefloquine and the racemate by IC50 equal to 1.17 μM in comparison to 4.09 μM