Punica granatum: A plant with high potential for the synthesis of silver nanoparticles

Abstract

Objective: To use extracts of pomegranate as a reducing agent to the simple and eco-friendly biosynthesis of silver nanoparticles and their antimicrobial evaluation against different bacteria. Methods: The peel of the ripe fruits and leaves of pomegranate were used to prepare aqueous and methanolic extracts to synthesize silver nanoparticles (AgNP) these nanoparticles were evaluated by techniques used for the characterization of nanoparticles that allow defining their size, shape and quality of dispersion in aqueous media. They were characterized by UV-Vis spectroscopy and dynamic light scattering (DLS). The antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis y Staphylococcus aureus was determined. Results: UV-Vis spectra with absorption peaks at 425 nm were observed for the nanoparticles synthesized with aqueous extract as well as for the nanoparticles synthesized with the methanolic extract. Regarding the size distribution and dispersion in solution, the zeta potential shows that the surface charge in all cases is negative with an average value from -28.0 mV to -52.0 mV. About the size, smaller nanoparticles were obtained from the aqueous extracts of the peel and leaf with values between 1.42 - 2.96 nm and10 - 19.04 nm for nanoparticles from the methanolic extracts. Inhibition of microorganisms by nanoparticles showed better inhibition against Escherichia coli with a MIC of 0.83 µg/mL up to 6.68 µg/mL. Conclusions: This study suggest that pomegranate extracts synthesize small-sized, well-dispersed nanoparticles with almost spherical morphology, with good antimicrobial activity against gram-negative bacteria such as Escherichia coli.