For centuries, malaria was treated with the bark of Cinchona calisaya and Cinchona succirubra plants named “quinas” in Brazil, from which the quinine molecule was isolated. Other plant species known also as “quinas” are used to treat fever and malaria, like Deianira erubescens (roots and leaves), Strychnos pseudoquina (bark), and Remijia ferruginea (bark). Based on this popular knowledge, we evaluated the in vivo antimalarial activity of the ethanol crude extracts of these plant species in mice infected with Plasmodium berghei. Only Remijia ferruginea showed antimalarial activity, reducing parasitaemia and mortality at the highest dose tested. Its phytochemical analysis showed the presence of alkaloids but not quinine. The other two plant species were inactive.
Malaria is a human protozoan disease widespread in the Amazon region. In Brazil, most malaria cases at present are caused primarily by Plasmodium vivax, followed by Plasmodium falciparum. Several derivatives of the quinine molecule are used to treat acute symptomatic malaria including chloroquine, amodiaquine and mefloquine or, to prevent Plasmodium vivax late relapses, as primaquine and other 8-aminoquinolines. At present, malaria chemotherapy is complicated by drug-resistant strains of Plasmodium falciparum, including in the Amazon region, thus, new antimalarials are needed.