Antioxidant potentials of gum kondagogu-based metal nanocomposites: An in vitro study

The living cell carries out various biochemical reactions, generating reactive oxygen species (ROS) and other free radicals that can be neutralised by the natural antioxidants present. However, when the concentration of the ROS exceeds, supplementation with potential antioxidants with fewer side effects plays a role in their elimination. In this regard, bio-nanocomposites, due to their eco-friendly nature, are being largely explored. This study uses in vitro DPPH and ABTS free radical scavenging assay methodologies to evaluate the antioxidant potential of gum kondagogu (GK) based monometallic [Silver (Ag), Gold (Au), and Palladium (Pd)], bimetallic (Ag-Au, Ag-Pd, and Au-Pd) and trimetallic (Ag Au Pd) nanocomposites. The known antioxidant, ascorbic acid, served as the positive reference standard, while native gum was utilised as the negative control. The per cent free radical scavenging activities of GK-based nanocomposites by DPPH (2–20 µg mL −1 ) and ABTS (1–5 µg mL −1 ) assays were: AgNPs (68.36; 85.33), AuNPs (52.34; 58.63), PdNPs (72.19; 72.09), AgAuPdNPs (84.69; 67.90), Ag-Au (54.07;76.24), Ag-Pd (67.29;85.87) and Au-Pd (95.0; 79.30), respectively. Among all the nanocomposites, the bimetallic exhibited the highest antioxidant potential, followed by the trimetallic and the monometallic in a concentration-dependent manner. Further, the AuPdNPs exhibited the highest (95.0 %) scavenging activity at 5 µg mL −1 concentration and also the lowest IC 50 values of 0.87 ± 0.08 µg mL −1 in DPPH and 1.99 ± 0.10 µg mL −1 in ABTS assays. The present study demonstrated the antioxidant ability of the monometallic, bimetallic and the trimetallic nanocomposites and suggested that the presence of palladium greatly enhanced the antioxidant efficacy due to their synergistic properties.