Supplemental Dietary Nano Zinc Can Impart Higher Antioxidant Status by Modulating Cu-Zn SOD Expression

Zinc seems to be the most critical micronutrients dietary adequacy of which ensures optimum health and body defence. Considering its immunomodulation potency, zinc is often used for dietary fortification more particularly in face of challenges. However indiscriminate use of zinc as therapeutic agent often leads to secondary deficiencies of other critical nutrients due to the unwanted antagonism with other interacting nutrients available in gut. In the present study we targeted to devise a nano-structured zinc which will remain inert to other dietary micronutrients present in gut to ensure its high bioavailability. An environment benign colloidal chemistry route was employed for the synthesis of nano-dimensional zinc oxide. The microanalytical characterizations revealed that the apparent particle size of our nano-Zinc oxide ranged between 30-40 nm. The as-synthesized ZnO-NP was used for dietary fortification and the MTT assay confirmed the safe limit for its dietary inclusion. The antioxidant potential of the synthesized nano-zinc was evaluated in milk fish (Chanos chanos) considering it as a model organism. We have employed Cu-Zn SOD gene as molecular marker for antioxidant assessment with integral zinc binding sites. We have characterized Cu-Zn SOD gene in Chanos chanos for the first time and identified certain important zinc binding sites present in the Cu-Zn SOD. A significantly better expression profile of Cu-Zn SOD was observed among the fish fed dietary ZnO-NP and the best effect was observed when the fish feed was fortified with 20 ppm ZnO-NP. The outcome of this study ensures the higher bioavailability of the synthesized ZnO-NP to be assimilated into Cu-Zn SOD, which in turn imparts higher body antioxidant. Nano zinc being inert, may directly bind through the zinc binding sites of Cu-Zn SOD molecules thereby leads to its better expression and more antioxidant status through molecular interaction with other molecules through longevity regulating pathway as explored by the String and KEGG pathway analysis carried out in the present investigation.