Hemozoin (HZ) (HZ)

Hemozoin is an insoluble biocrystal produced by Plasmodium falciparum and other blood-feeding parasites to detoxify free heme released during the digestion of host hemoglobin (Sullivan, 2002, International Journal for Parasitology). Within the acidic digestive vacuole of the parasite, hemoglobin is proteolytically degraded to provide amino acids, a process that liberates ferriprotoporphyrin IX (heme). Free heme is highly toxic to the parasite as it generates reactive oxygen species and destabilizes cellular membranes (Egan, 2008, Journal of Inorganic Biochemistry). To mitigate this toxicity, the parasite sequesters heme into chemically inert hemozoin crystals. This crystallization process is the primary target for several classes of antimalarial drugs, particularly the 4-aminoquinolines like chloroquine. These drugs bind to the surface of the growing hemozoin crystals or to free heme, preventing further incorporation of heme into the crystal lattice (Weissbuch & Leiserowitz, 2008, Chemical Reviews). The resulting buildup of toxic free heme leads to the lysis of the digestive vacuole and the eventual death of the parasite.

Other names

Malaria pigmentBeta-hematinHeme biocrystal

Inhibition of heme biocrystallization into hemozoin, resulting in the accumulation of free ferriprotoporphyrin IX (heme), which is toxic to the parasite by causing membrane damage and oxidative stress.