Peningkatan Radikal Bebas Pada Eritrosit Yang Terinfeksi Oleh Plasmodium Falciparum

Especially in tropical area, there is high falciparum malaria morbidity and mortality which is caused by oxidative stress such as cerebral malaria. One of the causes of the oxidative stress is the process happening in the parasitized erythrocytes. Therefore, it is important to study the process that causes the oxidative stress in parasitized erythrocytes. The oxidative stress in non parasitized erythrocytes is caused by hemoglobin auto-oxidation. Reactive oxygen species (ROS) production in the parasite food vacuoles happens because of a producing ROS reaction cascade  and the hemoglobin digestion that produces toxic heme which should be biomineralized. Part of this heme escapes from the biomineralization and moves from the parasite food vacuoles into the parasite cytosol which also needs to be detoxified and sequestrated by using GSH. Parasite mitochondrial activity produces superoxide anion and hydrogen peroxide, which is  then changed to be water and oxygen by thioredoxin consuming enzyme. However, there is no thioredoxin reductase to reduce thioredoxin. Lipoic acid protein ligase (LplA) metabolites ligates lipoic acid to E2-subunit of KADH (mitochondrial α keto acid dehydrogenase), which then reduces thioredoxin by using NADH. Part of this H2O2 also escapes from the detoxification and is exported to the parasite cytosol. The antioxidant system in the parasite cytosol includes superoxide dismutase, glutathione reductase, and thioredoxin reductase. The detoxification of H2O2 is carried out by using GST (glutathione S transferase) and 1 cys peroxyredoxin with GSH as cofactor,  and by 2 cys peroxyredoxin with thioredoxin as cofactor. Plasmodium has neither glutathione peroxydase nor catalase. Part of GSSG as redox product in Plasmodium  is exported to the erythrocyte cytosol and it causes oxidative stress in this cell. Hence, antioxidant supplementation must be considered in treating malaria especially in serious cases