The search for new antimalarial drugs from plants used to treat fever and malaria or plants ramdomly selected: A review

In this review we discuss the ongoing situation of human malaria in the Bra zilian Amazon, where it is endemic causing over 610,000 new acute cases yea rly, a number which is on the increase. This is partly a result of drug res istant parasites and new antimalarial drugs are urgently needed. The approa ches we have used in the search of new drugs during decades are now reviewe d and include ethnopharmocology, plants randomly selected, extracts or isol ated substances from plants shown to be active against the blood stage para sites in our previous studies. Emphasis is given on the medicinal plant Bid ens pilosa, proven to be active against the parasite blood stages in tests using freshly prepared plant extracts. The anti-sporozoite activity of one plant used in the Brazilian endemic area to prevent malaria is also describ ed, the so called "Indian beer" (Ampelozizyphus amazonicus, Rhamnaceae). Fr eshly prepared extracts from the roots of this plant were totally inactive against blood stage parasites, but active against sporozoites of Plasmodium gallinaceum or the primary exoerythrocytic stages reducing tissue parasiti sm in inoculated chickens. This result will be of practical importance if c onfirmed in mammalian malaria. Problems and perspectives in the search for antimalarial drugs are discussed as well as the toxicological and clinical trials to validate some of the active plants for public health use in Brazi l.