Objective: To investigate the antibacterial mechanisms of total flavonoids (TF) from Ampelopsis grossedentata on Staphylococcus aureus. Method: The antibacterial mechanisms were studied by scanning electron microscope for ultrastructural morphology of TF (155 mg·L-1). Microbial adhesion method was used for determination the effect of TF (155 mg·L-1) on cell-surface hydrophobicity of hydrocarbons. Cell permeability and conductivity colorimetric method were employed for the determination of dehydrogenase activity of S. aureus after being treated by different concentrations of total flavone(310-38.75 mg·L-1)from Ampelopsis grossedentata of Guangxi. Result: As the concentration increased and time prolonged

bacterial cell ultrastructural change was evident

characterized by cell surface uneven

warty protrusions

intercellular boundaries blurred

cell diameter increase. TF could significantly reduce the bacterial cell-surface hydrophobicity (P<0.01) and increase in permeability of the bacterial cell. Activity of bacterial dehydrogenase was obviously inhibited by TF. Conclusion: The antibacterial mechanisms of TF from Ampelopsis grossedentata on S. aureus are related with reducing surface hydrophobicity

increasing permeability of the bacterial and inhibiting dehydrogenase activity of S. aureus.