Vasavi H S, Arun A B, Rekha P D
Yenepoya Research Centre, Yenepoya University, Deralakatte, Mangalore, India.
Yenepoya Research Centre, Yenepoya University, Deralakatte, Mangalore, India.
J Microbiol Immunol Infect. 2016 Feb;49(1):8-15. doi: 10.1016/j.jmii.2014.03.012. Epub 2014 May 22.
BACKGROUND/PURPOSE: Inhibition of quorum sensing (QS), a cell-density dependent regulation of gene expression in bacteria by autoinducers is an attractive strategy for the development of antipathogenic agents.
In this study, the anti-QS activity of the ethanolic extract of the traditional herb Centella asiatica was investigated by the biosensor bioassay using Chromobacterium violaceum CV026. The effect of ethyl acetate fraction (CEA) from the bioassay-guided fractionation of ethanol extract on QS-regulated violacein production in C. violaceum ATCC12472 and pyocyanin production, proteolytic and elastolytic activities, swarming motility, and biofilm formation in Pseudomonas aeruginosa PAO1 were evaluated. Possible mechanism of QS-inhibitory action on autoinducer activity was determined by measuring the acyl homoserine lactone using C. violaceum ATCC31532. Anti-QS compounds in the CEA fraction were identified using thin layer chromatography biosensor overlay assay.
Ethanol extract of C. asiatica showed QS inhibition in C. violaceum CV026. Bioassay-guided fractionation of ethanol extract revealed that CEA was four times more active than the ethanol extract. CEA, at 400 μg/mL, completely inhibited violacein production in C. violaceum ATCC12472 without significantly affecting growth. CEA also showed inhibition of QS-regulated phenotypes, namely, pyocyanin production, elastolytic and proteolytic activities, swarming motility, and biofilm formation in P. aeruginosa PAO1 in a concentration-dependent manner. Thin layer chromatography of CEA with biosensor overlay showed anti-QS spot with an Rf value that corresponded with that of standard kaempferol.
The anti-QS nature of C. asiatica herb can be further exploited for the formulation of drugs targeting bacterial infections where pathogenicity is mediated through QS.
背景/目的：群体感应（QS）是细菌中一种由自诱导物介导的细胞密度依赖性基因表达调控机制，抑制群体感应是开发抗病原体药物的一种有吸引力的策略。
在本研究中，使用紫色杆菌CV026通过生物传感器生物测定法研究了传统草药积雪草乙醇提取物的抗群体感应活性。评估了乙醇提取物经生物测定指导分级分离得到的乙酸乙酯级分（CEA）对紫色杆菌ATCC12472中群体感应调节的紫菌素产生以及铜绿假单胞菌PAO1中绿脓菌素产生、蛋白水解和弹性蛋白酶活性、群游运动性和生物膜形成的影响。通过使用紫色杆菌ATCC31532测量酰基高丝氨酸内酯来确定群体感应抑制作用对自诱导物活性的可能机制。使用薄层色谱生物传感器覆盖分析鉴定CEA级分中的抗群体感应化合物。
积雪草乙醇提取物在紫色杆菌CV026中显示出群体感应抑制作用。乙醇提取物的生物测定指导分级分离表明，CEA的活性比乙醇提取物高四倍。400μg/mL的CEA完全抑制了紫色杆菌ATCC12472中紫菌素的产生，而对生长没有显著影响。CEA还以浓度依赖性方式抑制了群体感应调节的表型，即铜绿假单胞菌PAO1中绿脓菌素的产生、弹性蛋白酶和蛋白水解活性、群游运动性和生物膜形成。CEA的薄层色谱与生物传感器覆盖显示出抗群体感应斑点，其Rf值与标准山奈酚的Rf值相对应。
积雪草的抗群体感应特性可进一步用于开发针对通过群体感应介导致病性的细菌感染的药物制剂。
