Ferrous protoporphyrin IX (Fe(II)-PPIX)

Ferrous protoporphyrin IX (heme) is a critical molecule in the life cycle of Plasmodium falciparum, the primary causative agent of malaria. During the intraerythrocytic stage, the parasite ingests and degrades up to 80% of the host's hemoglobin within its acidic digestive vacuole to obtain essential amino acids (Source: PubMed, PMID: 21130010). This process releases large quantities of ferrous heme, which is rapidly oxidized to toxic ferric heme (hematin). To survive, the parasite detoxifies this heme by sequestering it into an insoluble crystalline polymer known as hemozoin or malaria pigment (Source: Nature Communications, PMID: 25973910). Ferrous heme specifically serves as a vital trigger for the activation of artemisinin-based compounds. The ferrous iron center reacts with the endoperoxide moiety of artemisinins, generating lethal free radicals that damage parasite membranes and proteins (Source: Science, PMID: 16179482). Consequently, the heme metabolism pathway and the physical site of hemozoin crystallization represent the most successful targets for current antimalarial chemotherapy, including both quinolines and artemisinins (Source: ACS Chemical Biology, PMID: 22260385).

Other names

Ferrous hemeHemeProtohemeHeme bIron(II) protoporphyrin IX

Artemisinins undergo reductive activation by the ferrous iron in heme, leading to the cleavage of their endoperoxide bridge and the generation of reactive carbon-centered radicals that alkylate parasite proteins. Quinolines primarily target the crystallized form or the transition to ferriprotoporphyrin IX (Fe(III)) to inhibit biocrystallization into non-toxic hemozoin.