Anti-oxidant defence (AD) system prevent oxidative cell damage through the coordinated expression of antioxidant defence enzymes. Main AD enzymes are: Mn SOD –mitochondrial manganese containing superoxide dismutase and CuZn-superoxide dismutase (SOD, EC 1.15.1.1), catalyses the dismutation of superoxide (O2.-) to hydrogen peroxide (H2O2) which is then independently converted to water by catalase (CAT, EC 1.11.1.6) or by selenium-dependent glutathione peroxidase (GSH-Px, EC 1.11.1.9) (Chance at al., 1979). Glutathione reductase (GR, EC 1.6.4.2) catalyses the reduction of oxidised GSH back into GSH, the latter being the co-substrate of GSH-Px (Gul et al., 2000). An imbalance between oxidative stress and the cell’s anti-oxidant defence system...