Antimicrobial Activity of Walnut Leaf Extract against Gram-Negative Bacteria

Abstract Nowadays, hospital-acquired infections caused by multidrug resistant bacterial strains are of great concern. Thus, the development of alternative natural antimicrobial compounds is more necessary than ever. Walnut (Juglans regia L,) leaves are an easily available source of natural compounds with antioxidant and antimicrobial properties. Due to these particular features, we evaluated the antimicrobial effect of the walnut. leaf methanolic extract at three different concentrations (30, 50 and 100 mg/L) against the two clinical strains Pseudomonas aeruginosa and Escherichia coli using the disc diffusion method. The results showed that both clinical strains were sensitive to all the extract concentrations tested. However, the diameter of the inhibition zone corresponding to 100 mg/L of extract concentration for P. aeruginosa was smaller than that for E. coli. These results demonstrate the potential of walnut leaves as an economical alternative source of antimicrobial agents.