According to the results of this study, the restorative impact of Met and/or Sem against T2DM and PD induced alterations in neurobehavioral and biochemical/molecular indices is attributed to the enhancement of endogenous antioxidant systems, reduced lipid peroxidation, suppression of oxidative/ inflammatory stress, and most importantly regulation of molecular markers of oxidant stress and tissue damage, Nrf2 and caspase 3. The gene discussed is CASP3; the disease is type 2 diabetes mellitus.