On the mechanism behind enhanced antibacterial activity of alkyl gallate esters against foodborne pathogens and its application in Chinese icefish preservation

摘要

The objective of this study was to investigate antibacterial activities and action mode of alkyl gallates against three food-related bacteria. Results show that the length of the alkyl chain plays a critical role in eliciting their antibacterial activities and octyl gallate (GAC8) exhibited an outstanding bactericidal effect against these strains. A possible bactericidal mechanism of GAC8 against E. coli was fully elucidated by analyzing associated changes in cellular functions of E. coli, including assessments of membrane modification and intracellular oxidation state. Our data strongly suggested that GAC8 functions outside and inside the bacterial membrane and causes increased intracellular reactive oxygen species (hydroxyl radicals) and subsequent oxidative damage. We demonstrated that the hydroxyl radical formation induced by GAC8 is the end product of an oxidative damage cellular death pathway involving a transient depletion of NADH, the tricarboxylic acid cycle, intrinsic redox cycling activities, and stimulation of the Fenton reaction. Also, chitosan-based edible films containing GAC8 have unique superiorities for icefish preservation at 4°C. This research highlights the effectiveness of GAC8 as an attractive antibacterial, which possesses both antioxidant and antibacterial activities and can be used as a multifunctional food additive combined with the benefit of active packaging for food preservations.