Multifaceted investigation of zinc oxide nanoparticles synthesized from Vernonia elaeagnifolia leaf extract: Characterization, antibacterial, antioxidant, cytotoxicity, and DNA binding activities

• This work presents an eco-friendly, cost-effective and sustainable synthesis of ZnO NPs using Vernonia elaeagnifolia . • The nanoparticles were characterized by various techniques, including UV–vis, FTIR, XRD, SEM, and Raman spectroscopy. • ZnO NPs showed antibacterial activity against Staphylococcus aureus and Escherichia coli . • Cytotoxicity assay revealed an IC50 value of 80 μg/ml against Hep3B liver cancer cells. • ZnO NPs interact with CT-DNA via electrostatic interactions or hydrogen bonding. In this study, Zinc oxide nanoparticles (ZnO NPs) were synthesized for the first time using an aqueous extract of Vernonia elaeagnifolia through a green, sustainable, and cost-effective method. The synthesized ZnO NPs were characterized using various spectroscopic techniques. Ultraviolet–visible (UV–Vis) spectroscopy revealed an absorption peak at 362 nm, confirming the presence of ZnO NPs. Dynamic light scattering (DLS) analysis, with a polydispersity index (PDI) value of 0.127, indicated a highly uniform size distribution. Fourier transform infrared (FTIR) spectroscopy exhibited IR bands at 923.96 cm −1 and 426.53 cm −1 , corresponding to Zn–O vibrations. X-ray diffraction (XRD) analysis determined the crystalline size of the ZnO NPs to be 45 nm. Raman spectroscopy shows a peak at 558 cm −1 , signifying Zn–O bond stretching. SEM results revealed the spherical shape of the ZnO NPs. The antioxidant potential of ZnO NPs was evaluated using DPPH (2,2-diphenyl-1-picrylhydrazyl) and hydrogen peroxide (H 2 O 2 ) scavenging assays, and the IC 50 values were found to be 256.1 μg/mL and 283.1 μg/mL, respectively. In antibacterial studies, ZnO NPs exhibited the highest inhibition zones of 16 mm against Staphylococcus aureus and 20 mm against Escherichia coli . Cytotoxicity analysis using the MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay on Hep3B cells revealed an IC 50 of 80 μg/mL, indicating potent anticancer activity. Furthermore, DNA-binding studies of ZnO NPs with calf thymus DNA (CT-DNA) suggested interactions through electrostatic forces or hydrogen bonding, as confirmed by UV–Vis, FTIR, Circular dichroism (CD) spectroscopy, and spectrofluorimetric analysis. Overall, this study highlights the successful green synthesis of ZnO NPs from Vernonia elaeagnifolia and their promising antioxidant, antibacterial, cytotoxic, and DNA-binding properties, indicating their potential for pharmacological and therapeutic applications.