Bacteriostatic activity of aquatic extract of black peel pomegranate and silver nanoparticles biosynthesized by using the extract

Black peel pomegranate is one of the rarest cultivars of Punica granatum that has not been studied precisely. However, selective cytotoxicity and potent antioxidant activity of the fruit peel extract have already been revealed. This study aimed to investigate the antibacterial activity of the extract, and silver nanoparticles synthesized by the extract, against gram-positive and gram-negative bacterial strains. Nanoparticles were characterized by UV-Vis spectroscopy, FE-SEM, and EDS, and their Zeta potential was also evaluated. According to the results, the spherical nanoparticles had an average size of 19 nm and the surface charge of -33 mV. Both extract and silver nanoparticles showed potent antibacterial activity against P. aeruginosa and S. aureus strains, although the gram-negative strain (P. aeruginosa) was less sensitive to these agents. Furthermore, these nanoparticles were able to kill the bacteria at very low concentrations (MBC = 40-65 mu g/ml), while no MBC for the extract was determined, confirming it is a bacteriostatic agent. The results determine that "black peel pomegranate" can be considered as a high potential agent to combat infectious diseases due to its significant bacteriostatic activity.