The action of 2:4-diamino-6:7-diisopropylpteridine on normal, proguanil- and sulphadiazine-resistant strains ofPlasmodium gallinaceum

Abstract

1. 2:4-diamino-6:7-diisopropylpteridine has an antimalarial index of 1:40, when tested againstPlasmodium gallinaceum.2. 2:4-diamino-1′-methylindolo-(2′:3′-6:7)-pteridine showed no activity againstP. gallinaceumin doses tolerated by the chick.3. Proguanil- and sulphadiazine-proguanil-resistant strains ofP. gallinaceumwere cross-resistant to 2:4-diamino-6:7-diphenylpteridine.4. Proguanil- and sulphadiazine-proguanil-resistant strains ofP. gallinaceumshowed no cross-resistance to 2:4-diamino-6:7-diisopropylpteridine, but were slightly hypersensitive to this compound.I wish to thank Dr A. Bishop for her interest in this work, and for advice and criticism. The work has been financed by the Medical Research Council.