Pharmacological activity of Curarea toxicofera in combination with classical antimalarial treatments

In the Leticia-Amazonas area, Uitoto indigenous people use a preparation of Curarea toxicofera (Wedd) Barneby & Krukoff (Menispermaceae) alone or combined with prescribed medications to prevent and treat malaria.

To determine the in vitro and in vivo antiplasmodial activity of traditional preparations of Curarea toxicofera alone and in combination with classical antimalarials.

The traditional preparation was evaluated in vitro against P. falciparum FCR3 CQ resistant strain, alone and combined. The preparation was further administered orally alone or combined with chloroquine and artesunate in mice infected with Plasmodium berghei ANKA strain on the four-day antimalarial test model.

The herbal remedy used alone was able to significantly decrease the parasitemia both in vitro (IC₅₀ 7.3 µg/ml) and in vivo (ED₅₀ 328 mg/Kg) but it was less active than chloroquine (IC₅₀ 0.29 µg/ml in vitro and ED₅₀ 2.3 mg/Kg/day in vivo), and than artesunate (IC₅₀ 0.002 µg/ml and ED₅₀ 3.7 mg/Kg/day). Interestingly it presented synergism with chloroquine in vitro (Combination Index: 0.39) and in vivo; and was additive with artesunate in vitro (Combination Index: 0.94) and in vivo.

The traditional preparation showed potential as an antimalarial and, when used in combination, does not negatively affect the efficacy of the drugs evaluated. Pre-clinical studies should be conducted with a standardized preparation to confirm its efficacy and safety alone and in combination with chloroquine and artesunate.