Biogenic synthesis of copper oxide nanoparticles from Ricinus communis L. leaf extract and their cytotoxic and pro-apoptotic effects on tumor cell lines

Copper oxide nanoparticles (CuONPs) were synthesized via an eco-friendly method using aqueous leaf extract of Ricinus communis L. Phytochemical analysis revealed the presence of flavonoids, phenols, and alkaloids, which mediated the reduction and stabilization of nanoparticles. The CuONPs were characterized using UV–Vis spectroscopy, FTIR, XRD, SEM, and EDX techniques. XRD results confirmed a monoclinic crystalline phase with an average crystallite size of ∼25 nm, while SEM images showed uniformly dispersed spherical particles (25–30 nm). The nanoscale morphology facilitated cellular uptake and enhanced surface reactivity, thereby promoting the generation of reactive oxygen species (ROS). CuONPs exhibited dose-dependent cytotoxicity against cancer cell lines with IC₅₀ values of 281 μg/mL (A-549 lung), 795 μg/mL (MCF-7 breast), and 1022 μg/mL (HepG-2 liver), compared to 1467 μg/mL in normal HEK293 cells. Selectivity index (SI) analysis demonstrated preferential toxicity toward A-549 cells (SI = 5.22), while SI values for MCF-7 (1.85) and HepG-2 (1.44) were below the therapeutic threshold. Flow cytometry confirmed apoptosis in 11.1 % of A-549 cells at the IC₅₀ concentration, validated by Annexin V/PI staining and nuclear condensation. Overall, R. communis -mediated synthesis offers a sustainable route to structurally optimized CuONPs with selective antiproliferative and pro-apoptotic activity, which is particularly promising for lung cancer therapy.