Eco-friendly copper oxide nanoparticles (CuO NPs) synthesized from aqueous Arachis hypogaea seed extract with enhanced antioxidant and antibacterial activities

Abstract

Using plant extracts for the green synthesis of metal oxide nanoparticles offers a sustainable, cost-effective, and environmentally friendly alternative to conventional chemical and physical methods. Copper oxide nanoparticles (CuO NPs) were produced in this study using the aqueous extract of Arachis hypogaea (peanut) seeds as a natural reducing and stabilizing agent, where the presence of flavonoids, alkaloids, phenols, tannins, and saponins was revealed in the extracts of Arachis hypogaea seeds. The formation, crystalline structure, morphology, and functional groups of the biosynthesized CuO NPs were verified using UV–vis spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The XRD analysis revealed a monoclinic crystal structure with an average crystallite size of approximately 23.54 nm, while SEM images indicated a quasi-spherical morphology and average size 2.27 nm. Antioxidant activity was evaluated by DPPH radical scavenging assay, which showed scavenging activity in a concentration dependent manner with IC50 value of 80.83 μg/mL ( Arachis hypogaea extract) and 100.7 μg/mL (CuO-NPs). The antibacterial activity was evaluated against Gram-positive and Gram-negative bacterial strains using the agar well diffusion method. The synthesized CuO NPs showed significant inhibition zones, especially for S. aureus, E. coli , and S. typhi , with 22 mm, 20 mm, and 17 mm, respectively. These findings highlight the promising potential of A. hypogaea seed extract as an effective bioresource for the green synthesis of CuO NPs with promising antioxidant and antibacterial properties for biomedical and pharmaceutical applications.