Ferrous heme (Plasmodium digestive vacuole) (Fe²⁺-heme)

Plasmodium parasites digest host hemoglobin within an acidic digestive vacuole, releasing free heme (ferriprotoporphyrin IX) as a toxic byproduct (Egan, 2008, PMID: 18230034). To prevent cellular damage, the parasite detoxifies this heme by sequestering it into an insoluble crystalline form called hemozoin (Sullivan et al., 1996, PMID: 8599110). Ferrous heme (Fe²⁺-heme) is particularly significant as it acts as the primary activator for artemisinin-based antimalarials; the ferrous iron triggers the reductive cleavage of the drug's endoperoxide bridge, producing reactive free radicals that alkylate parasite proteins (Klonis et al., 2011, PMID: 21730148). Other drugs, such as quinolines, target this pathway by binding to heme and inhibiting its crystallization into hemozoin, leading to the accumulation of toxic heme species (Hempelmann, 2007, PMID: 17343618). This target is central to the efficacy of the most widely used antimalarial therapies, though its utility is increasingly challenged by the evolution of parasite resistance mechanisms (Haldar et al., 2018, PMID: 29456225).

Other names

HemeFerroprotoporphyrin IXFerriprotoporphyrin IXHematinMalaria pigment precursorFree heme

Activation of endoperoxide antimalarials via iron-mediated radical generation; Inhibition of heme biocrystallization into hemozoin (PMID: 15769467, PMID: 8599110).