“…However, the high performance of GPx activity depends on several factors, including its biodisponibility, levels of reduced glutathione (GSH) and presence of selenium, an important component of GPx active site (Jurkovic et al, 2008). If the GPx system is exhausted and becomes unable to purge the H 2 O 2 produced, the excess of this ROS may react with polyunsaturated fatty acids present in the sperm membrane, inducing lipid peroxidation (Morliere & Santus, 1998;Bansal & Bilaspuri, 2010). Furthermore, the remaining H 2 O 2 in the presence of transition metals, can be converted by the Fenton reaction in hydroxyl radical (Gutteridge, 1986;Denisov & Afanas'ev, 2005), considered an unstable ROS and thus mainly responsible for oxidative damage to biomolecules (i.e., proteins, lipids, DNA) (Aprioku, 2013;Meyerstein, 2013).…”