Critical roles of thiol-mediated antioxidant detoxification systems in the pathophysiology of Plasmodium falciparum-infected erythrocytes

Abstract

Paul C. Chikezie

Five species of intracellular protozoa of the genus Plasmodium cause malaria in human. The present review briefly highlighted the critical roles of thiol-mediated antioxidant detoxification systems in the pathophysiology of Plasmodium falciparum-infected erythrocytes that are required for the survival of the malarial parasite in hyperoxidative intracellular environment. Scientific search engines such as PubMed, Pubget, Medline, EMBASE, Google Scholar, ScienceDirect and SpringerLink were used to retrieve online publications from 1976 to 2015. Haemoglobin molecules that are taken up by the parasites’ acid food vacuoles lead to the spontaneous oxidation of haem iron from Fe2+ to Fe3+, formation of superoxide radicals (O2 •−), and subsequently, hydrogen peroxide (H2 O2 ) and hydroxyl radicals (•−OH), which are highly reactive and cytotoxic oxygen intermediates. Additionally, toxic haem (ferri/ferroprotoporhyrin IX (FPIX) that is released upon haemoglobin digestion is biomineralized to form inert haemozoin. P. falciparum reduced glutathione (PfGSH) is a cofactor for glutathione enzyme systems and mediates in direct reductive detoxification of the toxic byproduct of haemoglobin digestion-FPIX. The postulated role of P. falciparum glutathione S-transferase (PfGST) in the development of drug resistance in malarial parasites is still being controversially discussed. However, selective inhibition of PfGST and P. falciparum thioredoxin reductase (PfTrxR) identifies novel drug targets and potential chemotherapeutic strategy to combating malaria.