Green Synthesis of CuO and ZnO Nanoparticles using Eryngium foetidum Leaf Extract: Mechanistic Aspects, Antimicrobial, and Antioxidant Activities

Introduction: The green synthesis of nanomaterials offers notable advantages like environmental sustainability, low toxicity, and cost-effectiveness. Herein, Eryngium foetidum leaf extract was used for green synthesis of CuO and ZnO nanoparticles (NPs). Materials and methods: The synthesized NPs, yielded approximately 2 grams after being calcined for 6 hours at 400ºC. They were characterized by UV-vis spectroscopy, FTIR, XRD, FESEM, TEM, and EDX analysis. UV-V initially confirmed the formation of nanoparticles is spectroscopy, which showed λmax at 356 nm and 364 nm for CuO NPs, ZnO NPs, respectively. Results: The results of TEM analysis displayed that the prepared CuO and ZnO NPs were elliptical and rod-shaped, having particle sizes of 50.02 nm and 31.95 nm, respectively. Discussion: FTIR and HPLC analysis showed involvement of various polyphenols, including chlorogenic acid and quercetin, available in the leaf extract of E. foetidum, in the reduction and stabilization of Cu2+ to Cu0 and Zn2+ to Zn0. The synthesized nanoparticles exhibited strong anti- bacterial activities against four pathogenic bacterial strains, namely Enterbacter aerogenes, Staphylococcus aureus, Escherichia coli, and Bacillus subtilis; however, CuO NPs (E. coli, 38.5 mm>E. aerogenes, 29.25 mm>B. subtilis, 29.03 mm>S. aureus, 28.0 mm) exhibited higher antimicrobial activities than the ZnO NPs (B. subtilis, 22 mm>E. coli, 16 mm>S. aureus, 15 mm>E. aerogenes, 14.15 mm). Additionally, both the synthesized nanoparticles displayed good antioxidant activities with IC50 of 1.87 mg/mL for CuO NPs, and 0.985 mg/mL for ZnO NPs. Conclusion: The results showed that the synthesized CuO NPs and ZnO NPs can be used as promising antimicrobial agents, and antioxidants.