Husain Fohad M, Ahmad Iqbal, Al-Thubiani Abdullah S, Abulreesh Hussein H, AlHazza Ibrahim M, Aqil Farrukh
Department of Agricultural Microbiology, Faculty of Agricultural Sciences, Aligarh Muslim UniversityAligarh, India.
Department of Food Science and Nutrition, College of Food and Agriculture Sciences, King Saud UniversityRiyadh, Saudi Arabia.
Front Microbiol. 2017 Apr 24;8:727. doi: 10.3389/fmicb.2017.00727. eCollection 2017.
Quorum sensing (QS) is a global gene regulatory mechanism in bacteria for various traits including virulence factors. Disabling QS system with anti-infective agent is considered as a potential strategy to prevent bacterial infection. L. (mango) has been shown to possess various biological activities including anti-QS. This study investigates the efficacy of leaf extracts on QS-regulated virulence factors and biofilm formation in Gram negative pathogens. Mango leaf (ML) extract was tested for QS inhibition and QS-regulated virulence factors using various indicator strains. It was further correlated with the biofilm inhibition and confirmed by electron microscopy. Phytochemical analysis was carried out using ultra performance liquid chromatography (UPLC) and gas chromatography-mass spectrometry (GC-MS) analysis. evaluation of anti-QS activity of ML extracts against revealed promising dose-dependent interference in violacein production, by methanol extract. QS inhibitory activity is also demonstrated by reduction in elastase (76%), total protease (56%), pyocyanin (89%), chitinase (55%), exopolysaccharide production (58%) and swarming motility (74%) in PAO1 at 800 μg/ml concentration. Biofilm formation by PAO1 and WAF38 was reduced considerably (36-82%) over control. The inhibition of biofilm was also observed by scanning electron microscopy. Moreover, ML extracts significantly reduced mortality of pre-infected with PAO1 at the tested concentration. Phytochemical analysis of active extracts revealed very high content of phenolics in methanol extract and a total of 14 compounds were detected by GC-MS and UPLC. These findings suggest that phytochemicals from the ML could provide bioactive anti-infective and needs further investigation to isolate and uncover their therapeutic efficacy.
群体感应（QS）是细菌中一种用于调控包括毒力因子在内的各种性状的全局基因调控机制。使用抗感染剂使QS系统失活被认为是预防细菌感染的一种潜在策略。芒果已被证明具有包括抗群体感应在内的多种生物活性。本研究调查了叶提取物对革兰氏阴性病原体中群体感应调控的毒力因子和生物膜形成的功效。使用各种指示菌株测试了芒果叶（ML）提取物的群体感应抑制作用和群体感应调控的毒力因子。进一步将其与生物膜抑制相关联并通过电子显微镜进行了确认。使用超高效液相色谱（UPLC）和气相色谱 - 质谱联用（GC - MS）分析进行了植物化学分析。对ML提取物针对紫色杆菌素产生的抗群体感应活性评估显示，甲醇提取物具有有前景的剂量依赖性干扰作用。在800μg/ml浓度下，铜绿假单胞菌PAO1中的弹性蛋白酶（76%）、总蛋白酶（56%）、绿脓菌素（89%）、几丁质酶（55%）、胞外多糖产生（58%）和群游运动性（74%）的降低也证明了群体感应抑制活性。与对照相比，PAO1和WAF38的生物膜形成显著减少（36 - 82%）。通过扫描电子显微镜也观察到了生物膜的抑制。此外，在测试浓度下，ML提取物显著降低了预先感染PAO1的线虫的死亡率。活性提取物的植物化学分析显示甲醇提取物中酚类含量非常高，通过GC - MS和UPLC共检测到14种化合物。这些发现表明，来自芒果叶的植物化学物质可能提供具有生物活性的抗感染作用，需要进一步研究以分离并揭示它们的治疗功效。
