Antimalarial activity of hydroxy-substituted naphthalene compounds.

A new series of mono- and di-hydroxy substituted naphthalene compounds was synthesized and found to possess antimalarial activity against P. gallinaceum infection of young chicks. A representative compound with a high degree of activity was chosen for extensive testing against other malarial species and for pharmacological investigation. The formula of this compound, number 377C54, was 1:6-dihydroxy-2:5-bis(cyclohexylaminomethyl)naphthalene dihydrochloride. Effective doses against P. gallinaceum in chicks, P. berghei in mice and P. cathemerium in canaries were 2.3, 4.0, and about 6 mg./kg. respectively. Compound 377C54 acted rapidly against the parasitaemia of P. gallinaceum in chicks and P. knowlesi in a rhesus monkey. Parasiticidal activity remained in the blood of chicks for a long time after a single oral dose. The drug can be estimated by the production of colour on coupling with diazotized p-nitroaniline. Drug concentrations in blood from chicks and humans rose rapidly after oral administration. In tissues from chicks, particularly liver and lung, the drug persisted for a long period. An unsuccessful attempt was made to induce resistance to 377C54 in a strain of P. gallinaceum. Extensive pharmacological investigation showed that 377C54 possessed no special pharmacological properties.