本研究旨在探讨原儿茶酸对副溶血弧菌的抑菌活性和减毒作用，揭示原儿茶酸抑菌的作用机制。通过测定最小抑菌浓度(Minimal Inhibitory Concentration, MIC)、生长曲线、核酸与蛋白质泄漏量、丙二醛(MDA)含量，利用扫描电镜观察副溶血弧菌形态的变化，来评估原儿茶酸对副溶血弧菌的抑菌活性及其对细胞膜完整性和通透性的影响。同时，通过检测亚抑菌浓度(Sub-inhibitory Concentrations, SICs)下原儿茶酸对副溶血弧菌毒力因子合成的影响，研究原儿茶酸对副溶血弧菌的毒力衰减作用。实验结果表明，原儿茶酸的MIC为2 mg/mL，经MIC浓度原儿茶酸处理后，副溶血弧菌发生严重内陷和破裂，上清液中核酸、蛋白质、MDA含量分别是对照组的2.65倍、1.94倍和10.05倍。此外，原儿茶酸在浓度为1/4 MIC时对胞外多糖、胞外蛋白酶、生物被膜的抑制率分别为40.57%、19.79%和26.04%，在浓度为1/2 MIC时的抑制率分别为52.85%、28.38%和34.69%。原儿茶酸主要作用于细胞膜，通过影响细胞膜的完整性和通透性抑制副溶血弧菌的生长，在亚抑菌浓度下便可有效减弱副溶血弧菌毒力。

The antimicrobial activity and antivirulence effect of protocatechuic acid (PCA) against Vibrio parahaemolyticus were investigated in this research to reveal the specific antibacterial mechanisms of PCA. To evaluate the antibacterial activity and the effect of PCA on the intergrity and permiaility of cell envelope, we determined the minimal inhibitory concentration (MIC), the growth curves, the leakage of nucleotide and protein, malondialdehyde content, and also observed the morphological changes of Vibrio parahaemolyticus treated with PCA by field emission scanning electron microscope. Meanwhile, the extracellular polysaccharide (EPS) productin, extracellular protease assay and biofilm formation with PCA at sub-inhibitory concentrations (SICs) were also examined to further analyze the antivirulence effect of PCA on V. parahaemolyticus. The results showed that the MIC of PCA against V. parahaemolyticus was 2 mg/mL. After treatment with PCA at MIC, Vibrio parahaemolyticus developed serious invagination and rupture in cell envelope. The contents of extracellular nucleic acid, protein, and MDA were 2.65 times, 1.94 times, and 10.05 times higher than those in the control group, respectively. In addition, the inhibition rates of PCA on extracellular polysaccharide, extracellular protease production, and biofilm formation were 40.57%, 19.79%, and 26.04%, respectively, at the concentration of 1/4 MIC and 52.85%, 28.38% and 34.69%, respectively, at 1/2 MIC. In conclusion, PCA mainly acts on cell membrane by affecting the integrity and permeability to inhibit the growth of Vibrio parahaemolyticus at sub-inhibitory concentrations.

国家自然科学基金面上项目(32070129, 31800328)；陕西省重点研发计划一般项目(2020NY-121, 2021NY-164)；西安市未央区科技计划项目(201937, 201940)；陕西科技大学博士启动项目(BJ12-24)