Green synthesis of copper oxide nanoparticles using Illicium verum Hook. f.: phytochemical characterization, apoptosis-mediated cytotoxicity activity, antioxidant potential, and metabolic enzyme inhibition

This study investigated the plant-mediated synthesis, physicochemical characteristics, and in vitro biological activities of copper oxide nanoparticles (CuO NPs) prepared using an ethanolic extract of Illicium verum Hook. f. (star anise). GC–MS profiling showed anisaldehyde (29.83%), anethole (20.72%), and anisyl methyl ketone (12.84%) as the predominant volatile constituents, while the available HPLC records provided retention-time-based assignments and concentration estimates for phenolic and flavonoid compounds, with the highest estimated values reported for apigenin (2651.60 ppm), pyrocatechol (685.89 ppm), and quinic acid (481.70 ppm). The synthesized material was characterized using UV–Vis spectroscopy, FTIR, XRD, TEM, SEM–EDX, and elemental mapping. An absorption maximum was observed at 353 nm, and XRD analysis indicated predominantly crystalline monoclinic CuO with a mean crystallite size of 11.18 ± 1.00 nm. TEM analysis of 70 particles revealed predominantly spherical to quasi-spherical morphologies with a mean particle diameter of 25.75 ± 8.57 nm. The CuO NPs produced concentration-dependent cytotoxicity against SKOV3 ovarian cancer and Vero cells, with IC₅₀ values of 196.08 and 395.54 µg/mL, respectively, corresponding to a selectivity index of 2.02. Exploratory flow-cytometric analysis showed apoptosis-associated changes and an increased G2/M DNA-content population following treatment. RT-qPCR analysis showed increased relative expression of caspase-3 and BAX and decreased Bcl-2 expression. The CuO NPs also exhibited cell-free antioxidant activity, with DPPH and ABTS IC₅₀ values of 154.15 and 342.94 µg/mL, respectively. In addition, they inhibited α-amylase, α-glucosidase, and pancreatic lipase in vitro, with IC₅₀ values of 323.78, 234.17, and 257.86 µg/mL, respectively. These findings provide an integrated phytochemical, physicochemical, and preliminary biological evaluation of I. verum -mediated CuO NPs while emphasizing the need for additional mechanistic, safety, and independently replicated studies.