Phytochemical licochalcone A enhances antimalarial activity of artemisinin in vitro.

Resistance to synthetic first-line antimalarial drugs is considered to be a major cause of increased malaria morbidity and mortality. Use of artemisinin-based combination therapies (ACTs) is being encouraged to reduce the malaria mortality in areas of falciparum resistance. Artemisinin is a natural product at times in short supply. With projected rise in demand of artemisinin there is an unmet need for alternate ACTs. Novel compounds that reduce dependence on artemisinin are required. In vitro cultures of Plasmodium falciparum provide a screen system for identifying and evaluating new drug combinations. Interactions of two phytochemicals, artemisinin and licochalcone A, has been studied against synchronized erythrocytic stages of chloroquine-sensitive 3D7 and chloroquine-resistant RKL 303 strains of P. falciparum. These two compounds in combination show synergistic antiplasmodial activity in vitro on these strains. Artemisinin but not licochalcone A interferes with hemozoin formation. Neither of the phytochemicals alone or in combination obstructs sorbitol-induced hemolysis.