Biogenic synthesis of zinc oxide nanoparticles by Coleus amboinicus extract: its spectral analysis and biological activities

Zinc oxide nanoparticles (ZnO NPs) were synthesized using Coleus amboinicus leaf extract (CALE) via a green synthesis approach. UV-Vis spectroscopy confirmed ZnO NPs formation, showing a broad peak at 335 nm. FTIR analysis identified phytochemicals involved in the formation and capping of ZnO NPs, enhancing stability. SEM imaging revealed irregular shaped ZnO NPs with size ranging in 20 nm - 50 nm, and EDAX confirmed the elemental compositions. ZnO NPs synthesized using CALE exhibited potent antioxidant activity in DPPH, H2O2, FRAP, ABTS, and NO assays. The high activity, dose-dependent inhibition, and synergistic effects of ZnO NPs and phytochemicals highlight their potential for use in biomedical and cosmetic applications to mitigate oxidative stress and inflammation. ZnO NPs synthesized from C. amboinicus exhibited minimal cytotoxicity at 20 µg/mL concentrations in brine shrimp. In osteosarcoma cells, ZnO NPs exerted a dose-dependent cytotoxic effect with an IC50 of 89.98 µg/mL. Morphological changes and apoptosis of osteosarcoma cells confirm ZnO NPs potential as an anticancer agent.