Antibacterial efficacy and mechanisms of hawthorn leaf extract against poultry-derived Staphylococcus aureus and Escherichia coli: potential as natural food preservatives.

The search for natural preservatives to enhance food safety is of increasing interest. This study assessed ethanol extracts (30%, 50%, 70%, and 95%) of hawthorn leaves against poultry-derived Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli)—two key pathogens in foodborne illness and antimicrobial resistance spread in the poultry chain—using inhibition zone, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) assays. Extract stability was evaluated under heat (100 °C), UV radiation, and different pH conditions (5–9). The 70% ethanol extract showed the strongest activity, with MIC and MBC values of 6.25 mg/mL and 25 mg/mL, respectively, and remained stable across treatments. Mechanistic studies suggested that the extract may impair cell wall and membrane integrity, as reflected by increased membrane permeability (1.21-fold higher protein leakage), and reduced metabolic activity by 21.43%. High-Performance Liquid Chromatography Quadrupole Time-of-Flight Tandem Mass Spectrometry (HPLC-QTOF-MS/MS) putatively identified 56 compounds, primarily flavonoids and polyphenols, which are likely responsible for underpinning its antibacterial efficacy. These results position hawthorn leaf extract as a promising multi-mechanism natural agent with potential for application in food preservation against relevant pathogens.