The role of superoxide dismutation in malaria parasites

Oxidant stress is associated with the generation of reactive oxygen species that are responsible for the damage of a variety of cellular components. T he prevention of such biological damage can be achieved by dismutation of s uperoxide to H2O2 which in turn is removed by catalase and GSH peroxidase. However, redox-active iron released during the development of plasmodia in the erythrocyte can mediate the conversion of H2O2 to hydroxyl radical whic h is more reactive. The roles of SOD and the nitroxide SOD mimic 4-OH,2,2,6 ,6,retramethyl piperidine-N-oxyl (Tempol) were examined in P. falciparum gr own in vitro. Both compounds did not prevent the interference with growth i nflicted by various inducers of oxidant stress. Moreover, Tempol inhibited parasite growth, in agreement with previous experiments depicting accelerat ed mortality in SOD overexpressing mouse model of malaria. Probably, effect ive defense against ROS requires balanced increments in antioxidant enzymes and is not necessarily improved by an increase in the activity of one enzy me.