POTENTIATION OF THE ANTIMALARIAL AGENT RUFIGALLOL

We have discovered a remarkable synergistic antimalarial interaction b etween rufigallol and the structurally similar compound exifone. The s ynergistic effects were produced in chloroquine-susceptible and chloro quine-resistant clones of Plasmodium falciparum. The degree of potenti ation as estimated by standard isobolar analysis was similar to 60-fol d for experiments initiated with asynchronous parasites. The most pron ounced synergism was observed in experiments with synchronized trophoz oite-infected erythrocytes, in which the degree of synergy was at leas t 300-fold. While the mechanism underlying this drug potentiation rema ins unresolved, it is hypothesized that rufigallol acts in pro-oxidant fashion to produce oxygen radicals inside parasitized erythrocytes. T hese radicals would attack exifone, thereby initiating its transformat ion into a more potent compound, a xanthone.