Antibacterial activity of phenolic compounds derived from Ginkgo biloba sarcotestas against food-borne pathogens

Aims: We investigated the antibacterial activity of three groups of phenolic compounds obtained from the chloroform (CHCl3) extract of the fleshy seed coat (sarcotestas) of Ginkgo biloba. Study Design: An experimental study. Methodology: Inhibition of microbial growth was measured by an agar diffusion method and susceptibility tests were performed by the broth microdilution method. Bactericidal effect of Ginkgo biloba compound 5-7 against Salmonella enterica serovar Typhimurium was assessed by time-kill assay. Results: Ginkgo biloba compounds 5-7 and 8-10 showed high antimicrobial activity against Gram-positive and Gram-negative bacteria, including several food-borne pathogens. In particular, compounds 5-7 and 8-10, containing phenolic acids and bilobols, respectively, were highly effective against Salmonella enteric serovar Typhimurium, Listeria monocytogenes, Listeria innocua, Streptococcus pyogenes, Escherichia coli, and Shigella dysenteriae. On the opposite, compounds 1-4, containing cardanols, showed little antibacterial activity. Compounds 5-7 exerted a bactericidal and bacteriolytic effect on Salmonella enteric serovar Typhimurium with a Minimal Inhibitory Concentration (MIC) and a Minimal Bactericidal Concentration (MBC) of 8.3 µg ml-1. Conclusion: The results of this study indicate that phenolic compounds derived from Ginkgo biloba sarcotestas, because of their strong inhibitory characteristics towards food pathogens, can be considered ideal candidates for possible application in food microbiology due to their natural origins.