Bio-Reducing and Capping Potential of Breynia Disticha (Snowbush) Leaf Extract in Green Synthesis of Copper Oxide Nanoparticles and Antioxidant Activity

Green synthesis of metal oxide nanoparticles using plant extracts has gained significant attention due to its eco-friendly, cost-effective and sustainable nature. In this research, the Copper oxide nanoparticles (CuO NPs) were successfully synthesised via a green method using Breynia distichia leaf extract as a natural reducing and stabilising agent. Phytochemical analysis revealed the presence of flavonoids, phenolics, tannins, alkaloids, saponins, and terpenoids, which contributed to nanoparticle formation. The synthesis was reproducible, with pH values between 6.33–6.76 and consistent dark green colouration. Characterization confirmed the nanoscale formation of CuO: FTIR identified Cu–O bonds and capping biomolecules; XRD indicated a monoclinic tenorite structure (~ 12 nm); UV–Vis showed a surface plasmon resonance peak at 290 nm and a band gap of 4.28 eV; DLS revealed an average particle size of 34.61 nm with low polydispersity (PdI = 0.218); TGA demonstrated thermal stability up to ~ 250°C; and SEM-EDX confirmed nanosized particles with near 1:1 Cu:O stoichiometry. The nanoparticles displayed notable antioxidant activity, achieving 96.78% DPPH inhibition at 250 µg/mL with an IC₅₀ of 81.2 µg/mL. These findings highlight the potential of Breynia distichia for producing bioactive, thermally stable CuO NPs for biomedical and pharmaceutical applications. This work demonstrates a novel, sustainable approach for producing CuO nanoparticles with significant antioxidant potential suitable for biomedical and environmental application.