Abstract
Dihydromyricetin (DMY) has recently attracted increased interest due to its considerable health-promoting activities but there are few reports on its antibacterial activity and mechanism. In this paper, the activity and mechanisms of DMY from Ampelopsis grossedentata leaves against food-borne bacteria are investigated. Moreover, the effects of pH, thermal-processing, and metal ions on the antibacterial activity of DMY are also evaluated. The results show that DMY exhibits ideal antibacterial activity on five types of food-borne bacteria (Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Salmonella paratyphi, and Pseudomonas aeruginosa). The activities of DMY against bacteria are extremely sensitive to pH, thermal-processing, and metal ions. The morphology of the tested bacteria is changed and damaged more seriously with the exposure time of DMY. Furthermore, the results of the oxidative respiratory metabolism assay and the integrity of the cell membrane and wall tests revealed that the death of bacteria caused by DMY might be due to lysis of the cell wall, leakage of intracellular ingredients, and inhibition of the tricarboxylic acid cycle (TCA) pathway.
Highlights
Food spoilage, which leads to huge economic losses, shelf-life reduction, and food-borne diseases in the food industry every year, is the most prominent problem in food quality and safety
The aim of this study is to evaluate the antibacterial activity of DMY against five food-borne bacteria, investigate the effects of pH, thermal-processing, and metal ions on the antibacterial activity of DMY and disclose its mechanisms of antibacterial action by morphology observation, integrity of the cell membrane and wall, permeability of the cell membrane, and oxidative respiratory metabolism characteristics
The antibacterial activity of DMY was preliminary investigated by the disc-diffusion method using five food-borne microorganisms including two strains of Gram-positive bacteria (S. aureus and B. subtilis) and three strains of Gram-negative bacteria (E. coli, S. paratyphi, and P. aeruginosa), and revealed by the diameters of the inhibition zone (DIZs) observed on the agar plate (Table 1)
Summary
Food spoilage, which leads to huge economic losses, shelf-life reduction, and food-borne diseases in the food industry every year, is the most prominent problem in food quality and safety. The synthetic preservatives have been widely applied in food due to their low cost and ideal antibacterial capacity. The addition of these preservatives is restricted because of their toxicity. In consideration of this situation, many studies have explored the ability of natural antimicrobial components to replace normal synthetic preservatives, including phytochemicals (i.e., flavonoids [3], polyphenols, terpenoids [4], and isothiocyanates [5]), essential oils [6], antimicrobial enzymes
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