The reaction of artemisinin with hemin: a further insight into the mechanism

The mechanism of action of trioxane antimalarial drugs is still largely controversial and warrants further investigation. We report here on the direct reaction of artemisinin with hemin, carried out in DMSO, in the absence of reducing agents. The reaction was analysed, independently, by visible spectroscopy, HPLC-ESI/MS and 1H NMR. Two isomeric artemisinin–hemin long-lived adducts are unambiguously detected. Eventual degradation of the porphyrin ring and loss of the Soret band are observed as well. Implications of the present results for the mechanism of action of artemisinin-based antimalarials are discussed.