all have similar structures and therefore are suppoosed to have the similar mechanisms of action. Often also a cross resistance of Plasmodium for more than one drug of this class of drugs is reported.
The intracellular trophozoite feeds on the haemoglobin of the red blood cell that serves as a source of amino acids. Digestion of the globin protein takes place inside the Plasmodium lysosome resulting in the generation of free haem (ferriprotoporphyrin IX, FP). The latter is insoluble and precipitates in the form of a black malaria pigment inside the lysosomes. Chloroquine in the lysosome interferes with pigment formation and the FP-chloroquine complex is highly toxic to the parasite.
Click here to read about chloroquine resistance
These drugs interfere with the synthesis of folic acid and by consequence with the synthesis of nucleotides required for DNA synthesis.