Antimicrobial, antioxidant and antitumor activities of silver nanoparticles synthesized by Allium cepa extract: A green approach

An economic and efficient method for the synthesis of silver nanoparticles (AgNPs) was performed using onion (Allium cepa) extract as reducing and capping agent. UV–vis spectroscopy confirmed the formation of silver nanoparticles by observing the typical surface plasmon resonance peak at 420 nm. Transmission electron microscopy studies revealed that AgNPs were spherical in shape with a size range of 10–23 nm. AgNPs were further demonstrated by the characteristic peaks observed in the XRD image. The possible functional groups of AgNPs were identified by FTIR analysis. AgNPs exhibited potential antimicrobial activity against all the microbial strains tested. Antioxidant activity of AgNPs revealed that they can be used as potential radical scavenger against deleterious damages caused by the free radicals. Additionally, AgNPs had antitumor activities against human breast (MCF-7), hepatocellular (HepG-2) and colon (HCT-116) carcinoma cell lines in a dose-dependent manner with IC50 of 1.6, 2.3 and 2.2 μg/ml, respectively. The overall results indicate promising baseline information for the potential uses of AgNPs in the treatment of infectious diseases and tumors.