Suppressive and causal prophylactic activity of floxacrine in various avian malaria models

Floxacrine, a 7-chloro-10-hydroxy-3(4-trifluoromethylphenyl)-3, 4-dihydroacridine-1,9-(2H, 10H)-dione and various standard malarials were found to be distinctly less active against avian malaria parasites than against rodent or nonhuman primate malaria parasites. Especially the suppressive action against asexual stages of P. gallinaceum, P. praecox and P. cathemerium was markedly reduced in comparison with that ascertained in mice infected with P. berghei. Similar results were observed in sporozoite-induced infections of P. gallinaceum and P. cathemerium respectively. Expressed as quotient of calculated causal prophylactic activity (CPD50) floxacrine was 42 and pyrimethamine 54 times more active against P. berghei yoelii than P. gallinaceum. The blood schizontocidal effect of floxacrine proved superior to that of mefloquine, chloroquine and mepacrine, whereas the causal prophylactic activity was slightly inferior to that of pyrimethamine but superior to that of primaquine. In vitro floxacrine revealed no effect against sporozoites of P. gallinaceum even at concentrations of 100 mcg/ml.