咖啡酸对铜绿假单胞菌群体感应的抑制及毒力因子降低的研究

Effect of Caffeic Acid on Quorum Sensing and Virulence Factors of Pseudomonas aeruginosa

摘要:

为了研究咖啡酸对铜绿假单胞菌群体感应及毒力因子和信号分子的抑制作用。采用紫色色杆菌定性定量法判断咖啡酸对群体感应的抑制效果，采用国际标准方法测定其对毒力因子和生物膜的抑制作用，采用UPLC-MS分析其对群体感应信号分子产量的影响。结果表明，咖啡酸在亚抑菌质量浓度下能显著抑制紫色杆菌素的产量，这揭示了咖啡酸的抑群体感应活性。而且，咖啡酸对铜绿假单胞菌的游动能力、生物膜和毒力因子（绿脓菌素和鼠李糖脂）均有显著的抑制作用。当咖啡酸质量浓度为0.4 mg/mL时，对铜绿假单胞菌生物膜、绿脓菌素和鼠李糖脂的抑制率分别为65.3%、66.4%和31.8%；对信号分子C4-HSL、C6-HSL、C8-HSL和3-oxo-C12-HSL的抑制率也分别达到了59.6%、49.2%、53.9% 和52.2%。这些发现表明，咖啡酸有潜能成为有效的群体感应抑制剂，其抑制机制可能是干扰信号分子AHLs的合成以干扰群体感应，同时抑制生物膜和毒力因子的表达，降低细菌毒力。

Abstract:

The inhibition effects of caffeic acid on quorum sensing（QS），virulence and signal molecules of Pseudomonas aeruginosa was studied. The effect on QS was determined using a biosensor bioassay with C. violaceum. The effect of caffeic acid on virulence factors and biofilm formation of P. aeruginosa was investigated using standard methods. Then，the production of quorum sensing signals was evaluated through UPLC-MS analysis. The results exhibited that caffeic acid significantly inhibited production of violacein in C. violaceum at the concentrations below the sub-MIC，which revealed anti-QS activity. Moreover，caffeic acid exhibited significant inhibition in swarming motility，biofilm formation and virulence factors（pyocyanin and rhamnolipid） of P. aeruginosa. When the concentration of caffeic acid was 0.4 mg/mL，the inhibition rate of biofilm，pyocyanin and rhamnolipid of P. aeruginosa was 65.3%，66.4% and 31.8%，respectively；the inhibition rate of C4-HSL，C6-HSL，C8-HSL and 3-oxo-C12-HSL was up to 59.6%，49.2% ，53.9% and 52.2%，respectively. These findings indicated that caffeic acid had the potential to be effective inhibitor on QS，biofilm formation and virulence factors of P. aeruginosa. The mechanism of the inhibition on QS appeared to be interfering with AHL activity and modulating the synthesis of AHLs.