Parasite food vacuole membrane and lipid-associated heme (FV-heme)

The parasite food vacuole (FV), also known as the digestive vacuole, is a specialized lysosome-like organelle in Plasmodium species, the causative agents of malaria. During the intraerythrocytic stage, the parasite ingests and degrades host hemoglobin within the FV to obtain essential amino acids for growth (1.1.3, 1.1.5). This process releases large amounts of heme (ferriprotoporphyrin IX), which is highly toxic due to its ability to peroxidize lipids and inhibit vital enzymes (1.2.1, 1.2.5). To mitigate this toxicity, the parasite utilizes lipid-associated environments within or near the FV membrane to sequester heme into an insoluble, non-toxic crystalline polymer called hemozoin (1.3.2, 1.3.5). Many frontline antimalarial drugs, including chloroquine and artemisinin, target this detoxification pathway (1.2.1, 1.2.3). Chloroquine acts by binding to heme and preventing its incorporation into hemozoin, leading to the accumulation of toxic heme-drug complexes that lyse the vacuolar membrane (1.2.1, 1.2.4). Artemisinin derivatives are activated by the heme within the FV, generating reactive free radicals that alkylate parasite proteins and lipids, ultimately causing parasite death (1.1.3).

Other names

Digestive vacuoleFood vacuoleFerriprotoporphyrin IXHemozoin formation siteHeme detoxification pathwayMalarial pigment formation site

Inhibition of heme biocrystallization into hemozoin, accumulation of toxic free ferriprotoporphyrin IX, and generation of reactive oxygen species (ROS) through heme-mediated catalysis.