Biosynthesis of nickel oxide nanoparticles using ethnomedicinal plant Crotalaria pallida leaves extract: Evaluation of antibacterial, antioxidant, antiangiogenic, cytotoxicity and ROS expression against HCT-116 and PANC-1 cells

The present study, reports the green synthesis of NiO NPs using Crotalaria pallida leaf extract, an ethnomedicinal plant rich in bioactive phytochemicals that act as natural reducing and stabilizing agents. The formation of NiO NPs was confirmed by UV–visible spectroscopy, showing a characteristic absorption peak at 299 nm. FTIR analysis identified functional groups (O–H, C O, and N–H) involved in nanoparticle capping and stabilization. X-ray diffraction (XRD) revealed a crystalline cubic structure with an average crystallite size of 84.4 nm, while dynamic light scattering (DLS) determined a hydrodynamic diameter of 28 nm. The zeta potential of –30.4 mV confirmed high colloidal stability and SEM/TEM analyses showed quasi-spherical, uniformly dispersed nanoparticles. The NiO NPs exhibited potent antibacterial activity against both Gram positive and Gram negative bacteria and strong antioxidant activity, with radical scavenging percentages ranging from 24.46 % to 85.98 %. Antiangiogenic studies confirmed their inhibitory effect on blood vessel formation. MTT assays demonstrated time and dose dependent cytotoxicity against HCT-116 and PANC-1 cancer cell lines, with IC₅₀ values of 107.60–45.40 µg/mL and 153.69–11.22 µg/mL, respectively. Reactive oxygen species (ROS) analysis revealed a significant, concentration-dependent rise in intracellular ROS, suggesting oxidative stress mediated apoptosis as a possible cytotoxic mechanism. Further mechanistic investigations should evaluate the molecular pathways including caspase activation and mitochondrial dysfunction. In vivo experiments and targeted drug delivery models are also recommended to validate the biocompatibility, biodistribution, and therapeutic potential of green-synthesized NiO NPs for clinical and biomedical applications. • Green synthesis of NiO NPs using Crotalaria pallida leaf extract. • NiO NPs show strong antimicrobial action via membrane penetration. • NiO NPs exhibit significant anti-angiogenic potential. • NiO NPs are cytotoxic to HCT-116 and PANC-1 cancer cells. • ROS-induced apoptosis confirms oxidative stress-mediated cell death.