The antimalarial action on Plasmodium falciparum of qinghaosu and artesunate in combination with agents which modulate oxidant stress.

The antimalarial activity of qinghaosu (artemisinine) against Plasmodium falciparum in culture was enhanced by increased oxygen tension. Artesunate, a qinghaosu derivative, showed synergistic effects with miconazole, and with doxorubicin, both of which have been suggested to exert their chemotherapeutic effect through increasing the oxidant stress. In contrast, catalase, dithiothreitol and alpha-tocopherol reduced the effectiveness of qinghaosu in vitro. These results suggest that the action of qinghaosu and artesunate might involve increase in oxidant stress on the infected red cells.