Juglans regia and Ribes nigrum as potential nutraceuticals: Source of thermostable superoxide dismutase enzyme

In the present study, superoxide dismutase (SOD) extracted from dry fruits; Juglans regia (Walnut; W) and Ribes nigrum (Munakka; M) was partially purified into 0%-40% and 40%-80% fractions based on ammonium sulfate saturation levels. The partially purified fractions (0%-40%) exhibited purification level of 3.09- (W) and 3.22- (M) fold with specific activity 79.32 Umg^-1 (W) and 125.23 Umg^-1 (M). SOD from both the sources was found to be thermally stable, that is, 80°C (W) and 70°C (M). Kinetic studies showed K_m values to be 3.33 mM (W) and 2.86 mM (M), whereas the activation energy (E_a ) calculated as 24.52 KJ mol^-1 (W) and 26.25 KJ mol^-1 (M). Na⁺ , Mn²⁺ , and Ba²⁺ ions acted as potential inhibitors, whereas Fe²⁺ stimulated SOD from both the sources. Among these metal ions, Na⁺ exhibited uncompetitive inhibition in both cases; with K_i values of 0.7 mM (W) and 0.9 mM (M), suggesting the more prominent binding affinity and effectiveness. PRACTICAL APPLICATIONS: Awareness need to be created among people for multifactorial health benefits of nutraceuticals in day-to-day life. Nutritional consumption from fruits, nuts, and vegetables safeguard against various maladies like cardiovascular diseases, diabetes, and cancers. Superoxide dismutase (EC 1.15.1.1) is a standout among the most critical metal-containing enzymes that act as a main line of defense against oxidative stress. Antioxidant-based drugs and formulations have been developed in the recent years and research is emphasized on its impact on oxidative stress levels. In this study, Juglans regia (W) and Ribes nigrum (M) were found to have thermostable SOD enzyme with excellent antioxidant properties. Thermal stability of an enzyme improves its significance making it industry friendly with therapeutically vital products, alongside their utilization as supplement in numerous therapeutic formulations.