Antioxidant mechanisms enzymatic defenses against

Oxidative damage caused by reactive oxygen species has been called oxidative stress . Biological systems contain powerful enzymatic and non-enzymatic antioxidant mechanisms, and oxidative stress denotes a shift in the pro-oxidant/antioxidant balance in favor of the former (1). Reactive oxygen species are important mediators of several forms of cell damage in parasites and this discussion will focus on the defense mechanisms of parasites against these species. 

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