In vitro antimicrobial and antileishmanial evaluation of green-synthesized ZnO nanoparticles from Cirsium arvense

The emergence of antibiotic-resistant bacterial strains poses a serious public health challenge, urging the need for alternative therapeutic approaches. This study presents, for the first time, the green synthesis of zinc oxide nanoparticles (ZnO NPs) using Cirsium arvense leaf extract, offering a novel route for generating bioinspired therapeutic agents. The synthesized ZnO NPs were characterized through standard physicochemical techniques, confirming their structure and stability. A distinctive UV-Visible absorption peak at 330 nm validated the successful synthesis. FTIR analysis identified functional groups such as O-H, CC, and C-N stretches that contributed to the reduction, capping, and stabilization of the NPs. The average crystallite size calculated from XRD 14.95 nm was smaller than the particle size observed in SEM 18.25. This difference is attributed to the fact that XRD estimates the size of individual crystallites within the nanoparticles, whereas SEM provides the overall particle size, including possible agglomerates. Such variations are commonly reported in nanoparticle studies. EDX results showed zinc (42.47 %) and oxygen (15.17 %) as the main constituents. The ZnO NPs exhibited significant antibacterial activity against Salmonella enterica, E. coli, Staphylococcus aureus, and Staphylococcus epidermidis, with inhibition zones of 18.5 mm, 18.5 mm, 17.5 mm, and 18 mm respectively at 400 μg/ml. Furthermore, ZnO NPs displayed promising antileishmanial activity against Leishmania tropica promastigotes, with a notable mortality rate of 51.89 ± 0.48 % at 1000 μg/ml. These findings suggest that Cirsium arvense-mediated ZnO NPs hold potential as bioinspired therapeutic agents.