Antibacterial Activity and Cellular Effects of Huai Chrysanthemum Polyphenol Extract Against Foodborne Pathogens

Huai chrysanthemum (Chrysanthemum morifolium Ramat. cv. Huaiju), collected from Jiaozuo, Henan Province, China, is a medicinal and edible plant rich in phenolic compounds. Polyphenols are natural bioactive compounds with potential antibacterial activity. In this study, HPLC-MS/MS was used to identify and quantify the phenolic compounds in huai chrysanthemum polyphenol extract, and its antibacterial activity against representative Gram-negative and Gram-positive foodborne bacteria was evaluated. A total of 22 polyphenolic compounds were identified, including 10 phenolic acids, 10 flavonoids, and two other phenolic compounds. Caffeic acid was the predominant phenolic acid, while luteoloside was the predominant flavonoid. Flavonoids accounted for 94.03% of the total identified polyphenols. The extract inhibited the growth of both Escherichia coli and Staphylococcus aureus, with an MIC₈₀ of 12.5 mg/mL for both strains. Further analysis showed that the extract reduced intracellular protein content and ATP levels, increased extracellular alkaline phosphatase activity, altered cell surface charge, affected superoxide dismutase activity, and caused marked morphological changes in bacterial cells. These results suggested that the antibacterial effect of huai chrysanthemum polyphenol extract was related to cell envelope damage, energy metabolism disturbance, and redox imbalance. This study provided a basis for further application of huai chrysanthemum polyphenol extract as a natural antibacterial ingredient in food preservation.