Antimicrobial, anti-biofilm, and anticancer activities of green-synthesized silver nanoparticles using Crossostephium chinense (L.) Makino aqueous leaf extract.

The increasing burden of infectious diseases, driven by microbial pathogenicity and antimicrobial resistance, necessitates the development of effective and sustainable antimicrobial strategies. In that context, this study reports, for the first time, the green synthesis of silver nanoparticles (AgNPs) using an aqueous extract of Crossostephium chinense (L.) Makino (CC) leaves, wherein plant-derived phytochemicals act as natural reducing and capping agents. Mass spectrometric analyses of CC aqueous leaf extract identified 62 possible metabolites, including flavonoids, phenolics, and terpenoids, that possibly facilitate nanoparticle synthesis. The synthesized C. chinense-derived silver nanoparticles (CC-AgNPs) were characterized as moderately stable, crystalline, spherical with sizes ranging from 20-80 nm. CC-AgNPs displayed broad-spectrum antimicrobial activity, showing the greatest susceptibility in Bacillus subtilis and Pseudomonas aeruginosa, with a minimum inhibitory concentration (MIC) of 6 μg/mL, while electron microscopy confirmed severe structural damage to bacterial membranes. Furthermore, CC-AgNPs displayed strong antibiofilm activity, achieving up to 92% biofilm inhibition in B. subtilis at 12 μg/mL. The anticancer potential of CC-AgNPs was evaluated against breast cancer (MCF-7 and MDA-MB-231), chronic myelogenous leukemia (K562), and hepatoblastoma (HepG2) cell lines. Among these, MDA-MB-231 cells were the most sensitive, exhibiting the lowest IC50 value. Further mechanistic investigations in MDA-MB-231 cells demonstrated apoptosis induction, as evidenced by nuclear fragmentation, Annexin V/PI staining and activation of caspases. In conclusion, these findings highlight CC-AgNPs as promising candidates for antimicrobial, antibiofilm, and anticancer applications.