With an increasing focus on green technologies, this research aimed to synthesize copper oxide nanoparticles (CuO-NPs) using leaf extracts from Allahabad Safeda and Hisar Safeda for environmental and health protection. A range of concentrations of leaf extracts were employed in the synthesis of nanoparticles, utilizing 1–9% extract from Allahabad Safeda and 3–11% extract from Hisar Safeda. The synthesized CuO-NPs were characterized by UV–visible spectrophotometry, Dynamic light scattering, Fourier transform infrared spectroscopy, and Scanning electron microscope with energy-dispersive X-ray spectroscopy. CuO-NPs synthesized using 3% Allahabad Safeda extract and 5% Hisar Safeda extract exhibited a particle size of 15.88 nm and 14.05 nm, respectively. CuO-NPs synthesized with Allahabad Safeda extract exhibited superior antibacterial, antioxidant, antidiabetic, and photocatalytic properties. Their antibacterial tests demonstrated significant inhibition zones against Staphylococcus aureus (20.5 cm), Streptococcus latis (20.7 cm), Escherichia coli (19.5 cm), and Pseudomonas aeruginosa (19.7 mm). Additionally, CuO-NPs from Allahabad Safeda extract (70 µg/mL) exhibited 68.23% of scavenging activity against 2,2-diphenyl-1-picrylhydrazyl. Moreover, the same CuO-NPs at 100 µg/mL concentration showed 67.32% α-amylase inhibition and 75.18% α-glucosidase inhibition, confirming their antidiabetic activities. Furthermore, these nanoparticles demonstrated high performance in photocatalytic degradation, by degrading 82.31% methylene blue and 88.54% crystal violet within 150 min of UV irradiation. Overall, the findings highlight the feasibility of CuO-NPs synthesis using Allahabad Safeda extract and their potential applications in antibacterial treatment, combating diabetes, antioxidation, and environmentally friendly dye photodegradation process. Graphical Abstract

The use of agricultural waste offers an eco‐friendly and sustainable way to synthesize functional nanomaterials. In this study, silver oxide nanoparticles (AgO‐NPs) were synthesized by using peel extracts from Citrus deliciosa (CD) and Citrus nobilis (CN) through a green method. The bioactive compounds present in peel extracts act as natural reducing and stabilizing agents. UV–Visible spectroscopy showed a distinctive absorption peak in the range of 400–460 nm, confirming the successful formation of AgO‐NPs. Dynamic Light Scattering analysis revealed that the AgO‐NPs had hydrodynamic diameters between 14 to 55 nm. Scanning Electron Microscopy confirmed that the nanoparticles were mostly spherical. Fourier transform infrared spectroscopy identified functional groups on the nanoparticle surface. AgO‐NPs derived from CD peel extract showed significant antibacterial properties, with inhibition zones ranging from 19 to 21 mm against Shigella dysenteriae , Escherichia coli , Staphylococcus aureus , and Listeria monocytogenes . In antioxidant tests using the DPPH free radical scavenging assay, the CD‐derived AgO‐NPs achieved 65% inhibition at a concentration of 70 μg/mL, showing their strong ability to neutralize reactive oxygen species. Additionally, the α‐amylase and α‐glucosidase inhibition assays demonstrated notable in vitro enzyme inhibition by the AgO‐NPs. Beyond their biomedical uses, the CD‐derived AgO‐NPs showed strong photocatalytic activity, achieving 73.51% degradation of methylene blue (MO) and 71% degradation of methyl orange (MO) when exposed to UV light. Together, these multifunctional properties highlight the usefulness of AgO‐NPs made from citrus waste in both medical and environmental applications. Using fruit peel as a precursor not only adds value to agricultural waste but also supports circular economy efforts by promoting eco‐friendly and sustainable development of nanomaterials.