Heme polymerization site

Heme polymerization is a critical detoxification mechanism employed by Plasmodium parasites, the causative agents of malaria, during their intraerythrocytic life cycle stage (Sullivan, 2002, PMID: 12459215). As the parasite digests host hemoglobin within its acidic food vacuole to acquire essential amino acids, it releases free heme (ferriprotoporphyrin IX), which is highly toxic due to its ability to generate reactive oxygen species and destabilize biological membranes (Egan, 2008, DOI: 10.1016/j.jinorgbio.2008.06.002). To mitigate this toxicity, the parasite sequesters free heme into an insoluble, chemically inert crystalline polymer called hemozoin, often referred to as malaria pigment (Coronado et al., 2014, PMID: 25232707). This biocrystallization process is the primary target for several classes of antimalarial drugs, most notably the quinolines such as chloroquine and quinine. These drugs interfere with the polymerization process by binding to heme monomers or the growing crystal faces, leading to the accumulation of toxic free heme and subsequent parasite death (Hempelmann, 2007, PMID: 17442090). While highly effective, the utility of targeting this site is increasingly challenged by the emergence of resistant parasite strains that utilize efflux transporters to reduce drug concentration at the polymerization site (Fidock et al., 2000, PMID: 11039928).

Other names

Hemozoin formationHeme detoxification pathwayMalaria pigment formationFerriprotoporphyrin IX polymerizationFerriprotoporphyrin IX

Inhibition of the conversion of toxic free heme into insoluble hemozoin crystals, leading to the accumulation of ferriprotoporphyrin IX which causes oxidative stress and membrane damage in the parasite (Egan, 2008, DOI: 10.1016/j.jinorgbio.2008.06.002).