Antimalarial action of alloxan and 5,6-diamino-2,4-dihydroxy-pyrimidine in Plasmodium berghei

Three hours after iv administration of alloxan and 5,6-diamino-2,4-dihydroxy-pyrimidine to mice infected with chloroquine-sensitive (CS) and chloroquine-resistant (CR) strains of Plasmodium berghei, the 2 compounds showed remarkable antimalarial actions. Parasitemia in CS and CR infected mice were reduced by about 50%. Slight hemolysis was seen in mice treated with alloxan but not in mice treated with 5,6-diamino-2,4-dihydro-pyrimidine. Alloxan did not inhibit glutathione reductase activity and no alloxan-glutathione complex was produced. No relationship between the antimalarial effects of alloxan and hemolysis or GSH content were found. It is suggested that the antimalarial effects of the two agents may be due to the inhibition of dihydroorotic acid dehydrogenase.