Synthesis of Biogenic Silver Nanoparticles from Kalanchoe fedtschenkoi Extract and Their Anticancer and Antibacterial Activities

Green-synthesized nanoparticles are gaining widespread attention due to their eco-friendly production and broad biomedical potential. Kalanchoe fedtschenkoi Raym.-Hamet & H.Perrier, a widely cultivated medicinal plant, was explored in this study for its ability to mediate silver nanoparticle (AgNP) synthesis. Among leaf, root, stem, flower, and fruit, the leaf extract exhibited the most consistent and efficient synthesis, and was therefore selected for further analysis and biological evaluation. Silver nanoparticles synthesized using the leaf extract (Kf-L-AgNPs) were characterized by multiple analytical techniques. UV-Vis spectroscopy confirmed their formation with a characteristic SPR peak around 420 nm. The FESEM and TEM analyses revealed predominantly spherical nanoparticles with a size of around 25 nm. The HRTEM images showed clear lattice fringes, confirming their crystalline nature, while moderate agglomeration suggested interparticle interactions. Dynamic light scattering measurements indicated uniform size distribution, and Zeta Potential analysis revealed good colloidal stability with negative surface charges. X-ray diffraction studies confirmed the crystalline structure of pure metallic silver nanoparticles, and FTIR detected functional groups from the plant leaf extract involved in the reduction and capping processes. The EDS analysis confirmed silver as the dominant element along with bio-organic components from the extract. Biological evaluations demonstrated that Kf-L-AgNPs exhibit strong anticancer activity, with IC50 values of 34.81 ug/ml for MCF-7 (breast cancer) and 98.73 ug/ml for A549 (lung cancer) cell lines. Antibacterial assays revealed significant zones of inhibition against both Escherichia coli and Staphylococcus aureus, indicating broad-spectrum antimicrobial potential. Additionally, LC-MS-based metabolic profiling of the leaf extract identified key phytochemicals, viz., picein, lampranthin II, p-coumaroylputrescine, delavirdine, and (+/-)7-epi-jasmonic acid, which may have contributed to the synthesis and bioactivity of the nanoparticles. Kf-L-AgNPs synthesized via a green, plant-based approach show great promise as anticancer and antimicrobial agents, though further investigation is needed to explore their potential in pharmaceutical applications.