² School of Chemistry, University of the Punjab, Lahore, 54590, Pakistan;

³ Department of Chemistry, Division of Science and Technology, University of Education, Lahore 54770, Pakistan;

⁴ Department of Physics, College of Sciences, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia;

⁵ Department of Biochemistry, University of Veterinary and Animal Sciences, Lahore (Jhang-campus), Jhang 35200, Pakistan;

⁶ Institute of Chemistry, The Islamia University of Bahawalpur, Bahawalpur, Pakistan;

⁷ Department of Chemistry, The University of Lahore, Pakistan.

* Correspondence: nmalwadai@pnu.edu.sa

Withania coagulans fruit extract was used as a reducing and stabilizing agent in an eco-friendly synthesis process to prepare zinc oxide nanoparticles (NPs). Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction, scanning electron microscopy and ultraviolet–visible spectroscopy were used to characterize the NPs. The X-ray diffraction patterns revealed a crystalline hexagonal wurtzite phase with an estimated average crystallite size of approximately 9.25 nm. The presence of a unique absorption peak at 365 nm confirmed the formation of ZnO NPs. The morphological analysis showed unevenly shaped particles with aggregates of the NPs due to the presence of biomolecules on the surface. Effective bio-capping was confirmed by the FTIR analysis, which also showed Zn–O vibrational band at 582 cm⁻¹ and revealed the presence of phytochemical moieties from the extract on the NPs surface. Total phenolic content (TPC), total flavonoid content (TFC), linoleic acid oxidation inhibition and DPPH radical scavenging techniques were used to evaluate the antioxidant activity (AOA). Aqueous ethanol extracts showed a promising AOA and the highest concentrations of phenolics and flavonoids among the investigated solvents. Phenol red dye was used to evaluate the photocatalytic activity of the synthesized ZnO NPs under solar light radiation and a 90% degradation was observed in 240 minutes. This work highlights the potential uses of ZnO NPs in environmental remediation and associated biomedical disciplines by demonstrating an environmentally benign method for preparing the ZnO NPs with a significant AOA and photocatalytic efficiency.