hemozoin

Hemozoin, also called malaria pigment, is a crystalline pigment produced by various blood-feeding parasites, most notably Plasmodium species that cause malaria. It is formed during the digestion of hemoglobin, when the toxic free heme released from hemoglobin is detoxified through polymerization into an inert crystalline pigment within the parasite’s digestive vacuole.

The process yields β-hematin-like crystals composed of ferriprotoporphyrin IX units linked by iron-carboxylate bonds. Synthetic β-hematin mimics the natural pigment and is used in laboratory studies of drug action.

In the parasite, accumulation of hemozoin occurs within the food vacuole and is exported to the host’s phagocytes after parasite rupture.

Hemozoin is primarily a detoxification product rather than a functional pigment. Its crystals can provoke macrophage activation and inflammatory cytokine production, contributing to aspects of malaria pathology; a higher burden of hemozoin has been associated with more severe disease in some studies.

Detection and diagnostic relevance: In stained blood smears, hemozoin appears as dark brown to black granules inside parasitized erythrocytes and in phagocytes. Its presence can aid microscopy-based malaria diagnosis, and advanced imaging methods can quantify it for research or clinical assessment.

Clinical and research relevance: Many antimalarial drugs, such as chloroquine, exert their effects by interfering with hemozoin formation, causing toxic accumulation of heme within the parasite.