The intraperitoneal Plasmodium berghei-Pasteur infection of Swiss mice is not a system that is able to detect the antiplasmodial activity in the Pothomorphe plant extracts that are used as antimalarials in Brazilian endemic areas.

The antimalarial activity of the hexane and methanol extracts derived from the Brazilian plants Pothomorphe peltata and Pothomorphe umbellata-whose leaves are popularly employed in medicinal folk remedies for the treatment of malaria-was assessed through in vivo tests with the Peters method. The extracts were delivered to Plasmodium berghei-infected mice via the oral or the subcutaneous route. A suppressive effect on the parasitemia seemed to be evident when data regarding the intraperitoneal injection of Pothomorphe umbellata extracts were analyzed. However, a definitive conclusion on an effective antimalarial activity is not possible, as two distinct-"standard" and "slow"-patterns of parasitemia occurring at similar frequencies in both treated and untreated intraperitoneally infected mice were observed. Nevertheless, the existence of two distinct profiles of parasitemia was not clear among the animals that were infected via the intravenous route. These data indicate the need for further studies on the biological features of the host/parasite interaction in the intraperitoneally P. berghei-infected Swiss mice system to standardize the model and to improve its usefulness in the screening of antimalarial compounds.