Hossain Md Akil, Lee Seung-Jin, Park Ji-Yong, Reza Md Ahsanur, Kim Tae-Hwan, Lee Ki-Ja, Suh Joo-Won, Park Seung-Chun
College of Veterinary Medicine, Kyungpook National University, Daegu 702-701, South Korea.
College of Veterinary Medicine, Kyungpook National University, Daegu 702-701, South Korea; Institute of Clean Bio, Daejeon 301-212, South Korea.
J Ethnopharmacol. 2015 Nov 4;174:482-91. doi: 10.1016/j.jep.2015.08.049. Epub 2015 Aug 29.
Nymphaea tetragona is a widely distributed ornamental species with ethnomedicinal uses in the treatment of diarrhea, dysentery, eruptive fevers, and infections. The anti-infectious activities of this herb have already been assessed to clarify its traditional use as a medicine.
In this study, we aimed to verify the inhibitory effects of N. tetragona 50% methanol extract (NTME) on quorum sensing (QS)-controlled virulence factors of bacteria since QS and its virulence factors are novel targets for antimicrobial therapy.
The antibacterial activity of this extract was evaluated against Chromobacterium violaceum and Pseudomonas aeruginosa. The inhibition of the violacein pigment of C. violaceum by NTME was determined qualitative and quantitative using standard methods. The effects of NTME on swarming motility, biofilm viability, pyocyanin production, and LasA protease activity were evaluated using P. aeruginosa. Finally, the in vitro and in vivo cytotoxicity of NTME were verified by MTT assay and oral administration to rats, respectively.
The extract had concentration-dependent antibacterial activity against gram-negative bacteria. NTME at 1/2× minimum inhibitory concentration (MIC), 1× MIC and 2× MIC significantly lowered the levels of violacein of C. violaceum compared to that of the control. The swarming motility of P. aeruginosa was inhibited by ≥70% by treatment with 1/2× MIC of NTME. There were remarkable reductions in pyocyanin production and LasA protease activity in the overnight culture supernatant of P. aeruginosa supplemented with NTME when compared with that of the untreated control. The confocal micrographs of 24h biofilms of P. aeruginosa exposed to NTME exhibited a lower number of live cells than the control. No toxic effect was observed in in vitro and in vivo cytotoxicity assays of NTME.
NTME was demonstrated to have significant concentration-dependent inhibitory effects on quorum sensing-mediated virulence factors of bacteria with non-toxic properties, and could thus be a prospective quorum sensing inhibitor.
睡莲是一种分布广泛的观赏植物，在民族医学中用于治疗腹泻、痢疾、发疹性发热和感染。已对这种草药的抗感染活性进行了评估，以阐明其作为药物的传统用途。
在本研究中，我们旨在验证睡莲50%甲醇提取物（NTME）对细菌群体感应（QS）控制的毒力因子的抑制作用，因为QS及其毒力因子是抗菌治疗的新靶点。
评估该提取物对紫色杆菌和铜绿假单胞菌的抗菌活性。使用标准方法定性和定量测定NTME对紫色杆菌中紫色菌素色素的抑制作用。使用铜绿假单胞菌评估NTME对群体运动性、生物膜活力、绿脓菌素产生和LasA蛋白酶活性的影响。最后，分别通过MTT法和对大鼠口服给药验证NTME的体外和体内细胞毒性。
该提取物对革兰氏阴性菌具有浓度依赖性抗菌活性。与对照组相比，NTME在1/2×最低抑菌浓度（MIC）、1×MIC和2×MIC时显著降低了紫色杆菌中紫色菌素的水平。用1/2×MIC的NTME处理可使铜绿假单胞菌的群体运动性受到≥70%的抑制。与未处理的对照组相比，添加NTME的铜绿假单胞菌过夜培养上清液中的绿脓菌素产生和LasA蛋白酶活性显著降低。暴露于NTME的铜绿假单胞菌24小时生物膜的共聚焦显微镜图像显示活细胞数量比对照组少。在NTME的体外和体内细胞毒性试验中未观察到毒性作用。
NTME被证明对细菌群体感应介导的毒力因子具有显著的浓度依赖性抑制作用，且无毒，因此可能是一种有前景的群体感应抑制剂。
