Lysis of malarial parasites and erythrocytes by ferriprotoporphyrin IX-chloroquine and the inhibition of this effect by proteins

Abstract

Ferriprotoporphyrin IX(FP) lysed both erythrocytes and isolated Plasmodium falciparum as judged by decrease in turbidity of erythrocyte and parasite suspensions. The lytic effect of FP on erythrocytes was enhanced by chloroquine(CQ). In the presence of 2.5–20 μM CQ, 5 μM FP led to complete hemolysis within 45 min. However, the lytic effect of FP or FP-CQ on both erythrocytes and parasites was inhibited completely by proteins. The protein inhibition was non-specific. This finding, the failure of FP and FP-CQ to cause hemolysis and lysis of malarial parasites in a protein-containing medium, does not support the “FP-CQ complex hypothesis” for the antimalarial action of chloroquine.