Abstract The green synthesis of metal oxide nanoparticles has emerged as a sustainable and eco-friendly alternative to conventional chemical methods. Utilizing plant-derived phytochemicals as natural reducing and stabilizing agents, this approach eliminates hazardous chemicals and energy-intensive processes. Beyond environmental benefits, green synthesis influences the physicochemical and biological properties of nanoparticles by enhancing surface functionality, stability, and bioactivity. Zinc oxide nanoparticles are widely favored in biomedical applications due to their biocompatibility, affordability, and low toxicity. Their therapeutic effects, especially in anticancer and antibacterial applications, arise from their ability to generate reactive oxygen species, release Zn 2+ ions, and induce apoptosis. This study synthesized ZnO NPs via chemical and green routes using aqueous extracts from Medicago sativa , Euphorbia milii , Codiaeum variegatum , and Helianthus annuus . Structural analysis confirmed that green synthesis did not alter the ZnO crystalline structure. However, biological activities varied significantly by plant extract. Codiaeum variegatum -mediated ZnO NPs showed superior antioxidant activity (60.8% DPPH scavenging) and strong cytotoxicity against A549 lung cancer cells (94.7% reduction). Chemically synthesized ZnO NPs exhibited notable anti-inflammatory activity (90.4%). ZnO NPs from Medicago sativa demonstrated potent antidiabetic effects via α-amylase (86.5%) and α-glucosidase (85.7%) inhibition. All ZnO NPs inhibited the growth of Escherichia coli , Klebsiella pneumonia, Streptococcus pyrogenes , and Staphylococcus aureus with maximum MBC value 47.4 mg/ml of chemogenic ZnO NPs against S. aureus and 44.4 mg/ml for biogenic ZnO NPs against S. pyrogenes . Additionally, Medicago sativa ZnO NPs recorded the highest suppression of S. pyogenes biofilm formation by 79%. The obtained results highlight the role of green synthesis as an effective strategy to tailor ZnO NP bioactivity for biomedical applications.
Said et al. (2026) studied this question.