Soluble Synthetic Analogues of Malaria Pigment: Structure of Mesohematin Anhydride and its Interaction with Chloroquine in Solution

Changing the vinyl groups of hematin anhydride to either ethyl or hydrogen groups results in increased solubility (Por=porphyrin). Determination of the weak binding constants of the antimalarial drug chloroquine to dimers of these hematin anhydride analogues suggests that solution-phase heme/drug interactions alone are unlikely to be the origin of the action of the drug.