Plackett‒Burman and Box‒Behnken Designs for Optimizing Polygonum cognatum Meissn-Mediated AgNP Synthesis: Antifungal Activity Against Diverse Phytophthora spp.

Objective: This study aimed to develop an eco-friendly method for synthesizing silver nanoparticles (AgNPs) using Polygonum cognatum (Madimak) extract and optimize their production using statistical design of experiments. The synthesized AgNPs were characterized, and their antifungal activity against Phytophthora species was evaluated. Materyal ve Yöntem: Madimak extract served as a bio-reducing agent for the synthesis of AgNPs. The total and individual phenolic compound content of Madimak extract was characterized by UV‒Vis spectroscopy and UHPLC analyses. Optimization of AgNP yield was conducted through Plackett‒Burman and Box‒Behnken designs. Characterization of synthesized AgNPs was performed using UV‒Vis spectroscopy, FT‒IR, SEM‒EDS, and TEM. The antifungal activity of AgNPs against six Phytophthora species was determined through in vitro assays. Results: The results of the RSM optimization revealed a high AgNP yield under the optimized conditions, with a plant material amount of 5 g, a boiling temperature of 80°C, a boiling time of 20 minutes, an AgNO3 concentration of 10 mM, an extract volume of 2.5 ml, a microwave power of 600 watts, and a reaction time of 90 seconds. Characterization confirmed the formation of spherical AgNPs with an average size of 10.07 nm. FT‒IR analysis indicated the role of caffeic acid in AgNP synthesis. AgNPs exhibited antifungal activity against all tested Phytophthora species with EC50, MIC, and MFC values ranging from 47.44 to 118.80 µg ml-1, 400 to 600 µg ml-1, and 400 to 800 µg ml-1, respectively. Conclusion: AgNPs were successfully synthesized and the process optimized using Madimak extract in this study. The synthesized AgNPs revealed potent antifungal activity against Phytophthora species, indicating their potential as a sustainable alternative for managing Phytophthora diseases.