The invention provides a process for the production of a substance or composition for the treatment, by therapy or prophylaxis, of parasitic infections, in particular malarial infections such as Plasmodium falciparum infections, of the human or animal body. The process comprises extracting the substance or composition from roots of the plant species Dicoma anomala, by an extraction using an organic solvent to obtain a liquid extract containing the substance or composition and removing the solvent from the liquid extract to leave a dried extract containing the substance or composition. The invention extends also to the use of the substance or composition in the manufacture of a medicament or preparation for such treatment of infections; to a substance or composition for use in such treatment of said infections; to compounds for use in such treatment of said infections; and to a method of treating said infections using such compounds. ##STR00001##