Tests of 2,4-Diaminopyrimidines on Toxoplasmosis

Tests of several compounds of the 2,4diaminopyrimidine group have shown two members of the group, particularly 2,4-di- amino-5-(4'-chlorophenyl)-6-ethyl pyrimidine (DCEP), to be active agalnst toxoplasmosis.DCEP is an effective antimalarial drug, as shown by Falco and associates (1), with a proguanil equivalent of 40 against Plasmodium gallinaceuw4 and 200 against Plasmodium berghei.To test their antitoxoplasmic activity, DCEP and related pyrimidines were screened by our laboratory for their effect against Toxoplasma gondii in the mouse.We are reporting the results of these screening tests and more exten- sive tests with DCEP. MethodsYoung mice (weight about 20 gm.) of the NIH general purpose strain and a strain of T. gondii isolated by this laboratory from the Norway rat were used in the tests.With an intraperitoneal inoculum of 20,000 organisms, prepared by diluting peritoneal exudate with physiological saline, mice invariably died, usually in 7+± 1 days.Six mice so infected were used in the screening of each new drug.Un-