Plants have a complex network of enzymes, metabolites, and antioxidants to stop oxidative damage to cellular components. There has been a rise in the use of plant-derived nanoparticles recently. Although the precise mechanism is unknown, water-soluble radicals found in plant extracts may cause metals to be reduced and create their nanoparticles through biogenic processes (Devanthiran et al., 2021). Organic solvents, toxic and expensive chemicals, and harsh reducing agents are used in synthetic methods based on chemical processes to produce nanoparticles; disposal concerns have been raised due to these hazardous compounds on the surface of metal nanoparticles. The physical synthesis method eliminates all these effects but is expensive, produces a low yield, and requires much energy. The green synthesis of metal and metal oxide nanoparticles uses sonication, ionic liquids, microwaves, electrochemical reactions, extracts from natural sources, and supercritical fluids (Khodashenas and Ghorbani, 2014, Lee et al., 2016, Yallappa et al., 2013). This process is economical, non-toxic, and occurs in physiologically and ecologically safe conditions. It can be used safely in biomedical and pharmaceutical applications (Thakur and Verma, 2021). The age of the plants, the amount of light they receive, the soil they grow in, the temperature and humidity of the air around them, the altitude at which they are grown, as well as the organisms that live inside those plants, can all have an impact on the applications of plant-based species (Srivastava et al., 2020). Metal salt precursors are being reduced to become nanoparticles using biosynthetic materials or reduced cofactors. Functional groups like amino acids and carboxylic acids (Chandra et al., 2016, Nimbekar et al., 2021) significantly reduce metal into its nanoparticle form in biological resources. Some bioactive compounds that bind metal in the plant’s centre and form a complicated structure around it are thought to cause these plants therapeutic effects (Andleeb et al., 2021).

Flueggea leucopyrus Willd belongs to the Euphorbiaceae family, and traditional medicine employs it for various purposes, including cancer treatment, ulcers, antioxidants, and therapeutic uses that strengthen the immune system. Kumar et al. (2016) reviewed the literature on this plant and discovered that phytochemicals have a variety of antimicrobial, anti-inflammatory, antiarthritic, and wound-healing properties. Only silver and zinc metal nanoparticles have been reported using the Flueggea leucopyrus Willd plant in the literature (Vinnarasi et al., 2021). Synthesised ZnO nanoparticles using its fruit extract in hydro-methanolic media and evaluated their antioxidant activity for the first time. Kudle et al. (2013) used its leaves for silver nanoparticle synthesis and tested their antibacterial activity. Due to the rise in drug resistance, creating and testing novel antibiotic agents that can combat elevated bacterial resistance is now more important than ever. Because CuNPs have antimicrobial qualities, they are more successful in treating various topical infections caused by various bacteria (Chandraker et al., 2020; Kumar et al., 2023, Naradala, 2021, Seçkin, 2021; Wu et al., 2020). The bactericidal effect is greatly enhanced because of the large relative surface area and differences in surface charge and structure of the CuNPs, which increase contact with bacteria. Free radical scavengers and reduced production of reactive oxygen species in living things are crucial for adaptive immunity, antiageing, and anticarcinogenesis. Free radical buildup severely damages cell membranes in living systems. Nanoparticles made of metal have been found to have antioxidant properties (Chung et al., 2014). Excessive levels of glucose in the bloodstream (caused by insufficient insulin production by pancreatic islet cells) and increased urination are signs of the medical condition known as diabetes mellitus. The root causes are insufficient amounts of insulin, a decrease in the effectiveness of insulin, or too much glucose production from the liver. Nowadays, numerous treatments for diabetes mellitus can inhibit alpha-amylase, including on-hormonal, hormonal, medicinal plants, and nanoparticles (Kanjikar, 2019). According to recent research, elevated levels of copper ions can significantly reduce the activity of the digestive enzyme amylase, which controls blood sugar levels. CuNPs were discovered to be more effective at suppressing pancreatic alpha-amylase than other treatments. A copper nanoparticle-based drug delivery system is being developed as an alternative for the treatment of complications related to diabetes (Bhagwat et al., 2018). Because of the background herein, we have attempted to synthesise CuNPs using Flueggea leucopyrus Willd leaf extract, characterised them, and evaluated their antibacterial, antioxidant (DPPH), and antidiabetic potential.