Heme polymerization (Hemozoin formation)

Heme polymerization, also known as hemozoin formation or biocrystallization, is a critical detoxification pathway utilized by Plasmodium parasites during their intraerythrocytic developmental stage. As the parasite degrades host hemoglobin to obtain essential amino acids, it releases large quantities of free heme (ferriprotoporphyrin IX), which is highly toxic to the parasite due to its ability to generate reactive oxygen species and destabilize cellular membranes (Sullivan, 2002). To mitigate this toxicity, the parasite sequesters free heme into an insoluble, chemically inert crystalline pigment called hemozoin (Egan, 2008). This biocrystallization process occurs within the acidic environment of the parasite's digestive vacuole and is a primary target for several classes of antimalarial drugs, most notably the 4-aminoquinolines and quinoline methanols (Coronado et al., 2014). These drugs interfere with the process by binding to heme dimers or the growing faces of the hemozoin crystal, preventing further polymerization and causing the accumulation of toxic heme-drug complexes (Hempelmann, 2007). While this target has been highly effective for decades, the widespread emergence of resistance, often mediated by mutations in the PfCRT transporter, presents a major challenge in malaria treatment (Coronado et al., 2014).

Other names

Hemozoin formationHeme biocrystallizationβ-hematin formationHeme detoxification pathway

Inhibition of heme polymerization into hemozoin, leading to the accumulation of toxic free heme within the parasite digestive vacuole.