The alkaloids febrifugine was originally isolated from the roots of the Chinese shrub Dichroa febrifuga. Febrifugine showed an antimalarial activity 50-100 times higher than that of quinine. Febrifugine acts by causing an increase in NO production during the immunological response - increased production of NO by febrifugine plays an important role in host defense against malaria infection in mice. Also, febrifugine are known to inhibit prolyl-tRNA synthetase of malaria parasite Plasmodium falciparum.