Leaf versus flower: green-synthesized silver nanoparticles from Xanthoceras sorbifolia leaf extract reveal superior antimicrobial and cytotoxic efficacy

Abstract

Green-synthesized silver nanoparticles (AgNPs) have emerged as promising antimicrobial agents, yet optimizing their synthesis and understanding their biological mechanisms remain crucial challenges. This study reports the synthesis of AgNPs using Xanthoceras sorbifolia leaf and flower extracts, leveraging their phytochemical composition for green synthesis. High-performance liquid chromatography-mass spectrometry identified 38 metabolites, including flavonoids, terpenoids, and phenols, which served as reducing and stabilizing agents. Optimized synthesis conditions included pH 9, an extract concentration of 10 mg mL⁻¹, silver nitrate concentrations of 12 mM (leaf) and 10 mM (flower), and temperatures of 80 °C (leaf) and 70–80 °C (flower). AgNPs exhibited a uniform spherical shape, with mean diameters of 9.22 ± 1.97 nm (leaf-AgNPs) and 7.46 ± 1.58 nm (flower-AgNPs). Moreover, they demonstrated significant antibacterial activity against Staphylococcus aureus and Escherichia coli, with leaf-AgNPs showing superior efficacy (MIC: 16 μg mL⁻¹) compared with flower-AgNPs (MIC: 32 μg mL⁻¹). Furthermore, both types of AgNPs exhibited concentration-dependent cytotoxic effects against 4T1 and KYSE-150 cell lines through reactive oxygen species-mediated cytotoxicity, with leaf-AgNPs showing enhanced effectiveness. These findings demonstrate the potential of X. sorbifolia-derived AgNPs as promising candidates for biomedical applications, particularly as antimicrobial agents with potent cytotoxic activity against cancer cells.