Fruit peels represent an abundant source of bioactive compounds with potential applications in green nanotechnology and plant protection. This study comparatively evaluated ethanolic extracts obtained from pomegranate (Punica granatum L.), orange (Citrus sinensis Osbeck), and persimmon (Diospyros kaki L.) peels and the corresponding silver nanoparticle (AgNP)-containing phytosynthesis preparations. The extracts were characterized for phytochemical and antioxidant properties and used for AgNP phytosynthesis, followed by UV-Vis, FTIR, BF-STEM, and EDS characterization. Their effects on Triticum aestivum L., Zea mays L., and Cucumis sativus L., as well as their antifungal activity against selected fungal strains, were comparatively assessed. Pomegranate peel extract showed the highest total phenolic content (147.52 mg g⁻¹ fw) and the strongest antifungal activity against Penicillium hirsutum, with an inhibition zone of 30 mm, followed by orange (27 mm) and persimmon (17.33 mm) peel extracts. The AgNP-containing preparations generally produced lower inhibition zones than the corresponding crude extracts. Antioxidant activity also decreased following phytosynthesis, with the most pronounced reduction observed for the orange peel system (90.72% to 35.17%). Plant responses were species- and treatment-dependent, with maize showing the lowest overall sensitivity to the investigated treatments. Overall, the results demonstrate that conversion of fruit peel extracts into AgNP-containing preparations does not necessarily enhance their biological activity and emphasize the importance of considering both the phytochemical characteristics of the starting extracts and the biological target when developing fruit-waste-derived systems for potential plant-protection applications.

The evaluation of local natural resources and their sustainable use as alternatives for allopathic medicines or phytosanitary treatments based on chemical syntheses, is a priority of research worldwide. The aim of this research was to obtain Prunella vulgaris L. extracts through modern, ecofriendly methods, to evaluate their ability to biosynthesize silver nanoparticles (AgNPs), as well as the physicochemical characterization of AgNPs to determine the polyphenol content, antioxidant and antimicrobial activity as well as phytotoxicity of the resulting nanoformulations, through in vitro tests. Microscopic analysis of the extracts showed the spherical shape of AgNPs, especially in the biosynthesized samples from the microwave extracts. The sizes of the nanoparticles ranged between 8.64 and 13.84 nm. Microwave-assisted extraction favored the procurement of crude extracts from P. vulgaris herba with a high content of polyphenols (77.98 mg GAE/g dw⁻¹) and a correlated antioxidant activity. Rosmarinic acid was identified in all analyzed samples (61.8287–1.0031 mg/L). The extracts obtained using microwaves, in which the nanoparticles were also biosynthesized using microwaves, had the best antifungal activity against Fusarium oxysporum MUCL 791. The combination of antifungal properties with those of seedling growth stimulation are of major importance in plant culture, with the early stages of their life cycle requiring constant attention.