Abstract:Using the single factor test， the orthogonal test in combination with the verification test， the optimum extraction process of flavonoids （dihydromyricetin， myricetin， myricetin） from Ampelopsis grossedentata was studied in terms of the ethanol solvent concentration （50%， 60%， 70%， 80%， 90%）， the solid/liquid ratio [1∶15， 1∶20， 1∶25， 1∶30， 1∶35 （g/mL）]， extraction time （20， 40， 60， 80， 100 min）. The effect of A.grossedentata extract on the antibacterial activity of Vibrio harveyi was thus investigated. The minimum inhibitory concentration was determined with the Oxford cup method. Growth curve， cell membrane integrity and permeability， cell wall， and scanning electron microscope were applied to discuss the antibacterial activity and mechanism of A. grossedentata extract. The result showed that the optimum extraction conditions were an ethanol concentration of 80%， a solid/liquid ratio of 1∶30（g/mL）， and an extraction time of 60 minutes. Under these conditions， the diameter of the inhibitory zone of the A. grossedentata extract against V. harveyi was（23.67±0.17） mm and the minimum inhibit concentration of the A. grossedentata extract was 0.015 6 g/mL. After minimum inhibitory concentration（MIC） treatment， the A. grossedentata extract was found to have a good inhibitory effect on the growth curve of V. harveyi. It could destroy the integrity of the cell membrane， increase the permeability of the cell membrane， and cause the release of intracellular biomacromolecules. The cell wall of V. harveyi was damaged. The surface of the bacteria became rough， the lysed cytoplasm flowed out and the edge of the cells was blurred， indicating that the A. grossedentata extract had a strong inhibitory mechanism against V. harveyi.