中药厚朴中群体感应抑制剂的分离与活性评价

Isolation and Activity Evaluation of Quorum-Sensing Inhibitors from Magnolia Officinalis

目的:从中药厚朴中分离得到群体感应抑制剂,并对其活性进行评价。方法:利用铜绿假单胞菌QSIS-las I对中药厚朴的粗提物进行活性检测及追踪,采用生物自显影薄层色谱、制备薄层色谱和高效液相色谱技术,分离纯化厚朴中的活性化合物,应用核磁共振波谱解析确定其结构。分别利用分光光度法及地衣酚法测定绿脓菌素和鼠李糖脂的产量,并通过半固体培养基检测铜绿假单胞菌的swarming运动,利用RT-PCR检测与QS调控相关基因的m RNA表达的影响。结果:厚朴粗提物具有群体感应抑制活性,其活性化合物结构鉴定为和厚朴酚。亚抑菌浓度下的和厚朴酚能明显抑制毒力因子如鼠李糖脂和绿脓菌素的产量以及swarming运动,且能够有效抑制QS相关基因m RNA水平的表达(P<0.05)。结论:和厚朴酚是一种新的群体感应抑制剂,可能发展成为一种治疗细菌感染的潜在新药。

Objective： To find quorum sensing inhibitors（QSIs） from Chinese herbal medicine Magnolia officinalis and to evaluate its inhibitory activity. Methods： Pseudomonas aeruginosa QSIS-las I biosensor was used to monitor quorum sensing inhibitory activity.The bioactive compound in M. officinalis with anti-QS activity was separated by a bioautographic TLC assay, preparative TLC, and HPLC analysis. Its structure was identified by spectroscopic analysis. The pyocyanin and rhamnolipid production were determined by spectrophotometric method and orcinol method, respectively. And the swarming motility was assayed on semisolid agar plates. The effect of mRNA of QS-regulated gene was measured by RT-PCR. Results： M. officinalis extract was found to inhibit QS-controlled gene expression in P. aeruginosa QSIS-las I Biosensor. The active compound was purified and identified as honokiol. Honokiol at sub-inhibitory concentrations inhibited the production of virulence factors, including pyocyanin, rhamnolipid and swarming motility. It significantly reduced the level of mRNA of QS-related genes（P〈0.05）. Conclusions： Honokiol is a new QS inhibitor, which could be a potential agent for the treatment of bacterial infections.