Summary

A series of compounds was tested for antimalarial activity in vitro against the erythrocytic forms of Plasmodium gallinaceum. Chloroquine, quinacrine, quinine, and the naphthoquinone, SN 12,320, were active at concentrations approximating those found in the blood of adequately treated chicks. Pamaquine was relatively inactive in vitro, but when administered to chickens gave rise to active metabolic intermediates. Sulfadiazine, metachloridine, chlorguanide, and two of its metabolic intermediates from monkeys, a number of 2,4-diaminopyrimidines, and a 2,4-diaminopterin were relatively inactive in vitro.