Green Synthesized Magnolia alba Silver Nanoparticles Kill Pathogens, Inhibit Cancer, and Display Antioxidant and Photocatalytic Properties

The biosynthesis of silver nanoparticles has recently emerged as a promising approach in nanomedicine, particularly for targeted therapeutic applications. Green synthesized (plant-based) nanoparticles have been shown to offer enhanced reduction efficiency, greater bioavailability, and improved stability compared to synthetic nanoparticles. Here, we report the green synthesis of silver nanoparticles (AgNPs) using Magnolia alba leaf extract. The formation of these Magnolia-derived silver nanoparticles (MAgNPs) was verified through UV-Vis spectroscopy and further characterized by scanning electron microscopy (SEM) which showed that the MAgNPs have a mean diameter of 40 nm and a spherical morphology. The antibacterial efficacy of MAgNPs, evaluated by the well diffusion method, showed significant activity against E. coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Enterococcus faecalis, and strains of methicillin-resistant and -sensitive Staphylococcus aureus. Disc diffusion and plaque assays demonstrated notable antifungal activity against Candida albicans and antiviral activity against bacteriophage T7. In vitro studies with HCT-116 human colon cancer cells, MAgNPs exhibited significant bi-phasic inhibition of cancer cell growth. These effects were greater than that of the magnolia leaf extracts alone, confirming the green synthesized nanoparticles bioactive efficacy. These findings suggest that MAgNPs possess significant antimicrobial and anticancer activities, indicating their potential as therapeutic agents for certain infections and cancers. Antioxidant assays indicated that MAgNPs exhibit greater antioxidant activity than magnolia leaf extract alone. Results suggest that MAgNPs may have promise as antioxidants for treating free radical-induced disorders. Additionally, MAgNPs showed efficient photocatalytic degradation of the azo bond in methyl orange within 30 minutes, suggesting they may provide a sustainable approach to certain types of environmental pollution. To our knowledge, this is the first report of the biosynthesis of silver nanoparticles using Magnolia alba and examination of their antioxidant and photocatalytic properties, their killing and inhibitory effects on various bacteria, fungi, bacteriophages, and colon cancer.