Green Synthesis Of Agnps Using Binary Extracts Of Moringa Oleifera And Silybum Marianum For Antioxidant Applications

Abstract

A green synthesis approach was developed to produce silver nanoparticles (AgNPs) using an aqueous binary extract of Moringa oleifera leaves and Silybum marianum seeds. The mixture of plant extracts served as both reducing and capping agents, enabling a single-step biosynthesis. Upon mixing 1 mM AgNO₃ with the mixed extract (1:9 v/v) at room temperature, a rapid color change from pale yellow to dark brown indicated AgNP formation. UV–Vis spectroscopy confirmed nanoparticle synthesis by the appearance of a strong surface plasmon resonance (SPR) peak at ~430–435 nm. The AgNPs were then evaluated for antioxidant activity using the DPPH radical scavenging assay. Results showed dose-dependent free radical scavenging for both the binary extract and AgNPs, but the AgNPs exhibited significantly higher activity. At 100 µg/mL, the AgNPs achieved ~91% DPPH radical scavenging versus ~76% for the extract. The calculated IC₅₀ (concentration for 50% scavenging) was markedly lower for AgNPs (~45 µg/mL) than for the extract (~67 µg/mL), demonstrating enhanced antioxidant potency. The improved activity is attributed to the combined effect of silver and bioactive phytochemicals (e.g. flavonolignans, phenolics) acting synergistically on the nanoparticle surface. This eco-friendly synthesis avoids hazardous chemicals and yields biocompatible AgNPs with strong antioxidant capabilities, suggesting utility in biomedical and nutraceutical applications.