Naphthoquinone antimalarials of the general formula
have been introduced by Fieser and his collaborators (1). They have shown remarkable activity against avian malaria not only as suppressive but also as prophylactic and curative agents. Some compounds which were very potent in the avian infection proved ineffective in human malaria probably because they are degraded, mainly oxidized, in the human body into less active or inactive products.
One compound, M-1916,
has been tried in blood-induced malaria in man (P. vivax and P. falciparum) and it showed definite, although weak antimalarial activity. M-1916 is oxidized in the body to a new compound, which possesses about one tenth the activity of M-1916 but which persists in the blood for a long time. The weak antimalarial activity of M-1916 is thus to be attributed to the action of the oxidation product.