Published online by Cambridge University Press: 06 April 2009
1. 2:4-diamino-6:7-diisopropylpteridine has an antimalarial index of 1:40, when tested against Plasmodium gallinaceum.
2. 2:4-diamino-1′-methylindolo-(2′:3′-6:7)-pteridine showed no activity against P. gallinaceum in doses tolerated by the chick.
3. Proguanil- and sulphadiazine-proguanil-resistant strains of P. gallinaceum were cross-resistant to 2:4-diamino-6:7-diphenylpteridine.
4. Proguanil- and sulphadiazine-proguanil-resistant strains of P. gallinaceum showed 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.