Abstract:The use of plant-based medicines for the production of green nanomaterials represents a viable route for cancer treatment. In this study, we report a novel method for the biosynthesis of zinc oxide nanoparticles (ZnO NPs) using the leaf extract of Ruellia tuberosa L. a medicinal plant known for its therapeutic properties. The study aims to test and investigate the ability of these R. tuberosa-derived ZnO NPs (RT-ZnO NPs) to cause apoptosis in human prostate cancer (PC) cells and clarify their fundamental molecular pathways. The developed RT-ZnO NPs were analysed employing field emission scanning electron microscopy, which exhibited a spherical shape with a median particle size of 156.7 nm. The methylthiazolyldiphenyl-tetrazolium bromide experiment showed that RT-ZnO NPs demonstrated considerable cytotoxicity toward DU 145 PC cells, with an IC₅₀ value of 26.82 µg/mL, while demonstrating low toxicity against normal HPE-15 prostate epithelial cells. Furthermore, the molecular analysis demonstrated that the NPs boosted p53 expression while suppressing both total and phosphorylated STAT3, indicating that anticancer activity is mediated by the p53 and STAT3 signalling pathways. This study focuses on a green and cost-effective method for creating anticancer nanomaterials, with RT-ZnO NPs emerging as a potential alternative for PC therapy.