Research Article Synergistic Effect and Antiquorum Sensing Activity of Nymphaea tetragona (Water Lily) Extract Md. Akil Hossain, 1 Ji-Yong Park, 1,2 Jin-Yoon Kim, 1 Joo-Won Suh, 3 and Seung-Chun Park 1 1 Laboratory of Clinical Pharmacokinetics and Pharmacodynamics, Department of Pharmacology, College of Veterinary Medicine, Kyungpook National University, Daegu 702-701, Republic of Korea 2 Institute of Clean Bio, Daejeon 301-212, Republic of Korea 3 Division of Bioscience and Bioinformatics, Myongji University, Science Campus, Gyeonggi 449-728, Republic of Korea Correspondence should be addressed to Seung-Chun Park; parksch@knu.ac.kr Received 26 February 2014; Accepted 1 April 2014; Published 8 May 2014 Academic Editor: Kota V. Ramana Copyright © 2014 Md. Akil Hossain et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Salmonellosis is a common and widely distributed food borne disease where Salmonella typhimurium is one of the most important etiologic agents. he purpose of this study was to investigate the antimicrobial activity of Nymphaea tetragona alone and in combination with antibiotics against S. typhimurium. It also aimed to assess the plant for quorum sensing inhibition (QSI) activity and to identify the bioactive compounds. he antibacterial activities of the extract were assessed using broth microdilution method. Disk agar difusion method was employed to determine the QSI and bioactive compounds were identiied by GC-MS analysis. Ethyl acetate fraction of N. tetragona extract (EFNTE) demonstrated good antimicrobial activity (MIC 781 g/mL) against 4 strains out of 5. FIC index ranged from 0.375 to 1.031 between EFNTE/tylosin and 0.515 to 1.250 between EFNTE/streptomycin against S. typhimurium. Among all extracts, EFNTE and butanol fraction more signiicantly inhibited pigment production of C. violaceum. Polyphenols were identiied as major compound of EFNTE and butanol fraction. hese results indicate that combination among N. tetragona extract and antibiotics could be useful to combat drug-resistance Salmonella infections and polyphenols are promising new components from N. tetragona that warrant further investigation as a candidate anti-Salmonella agent and quorum sensing inhibitor. 1. Introduction Salmonella species are the leading cause of bacterial gastroen- teritis in humans and animals all over the world [1, 2]. Food animals and water are the most important reservoirs of the bacteria [2] where the outbreaks of Salmonella infections have increasingly been associated with processed foods [3, 4]. here are 1300 million cases of gastroenteritis, 16 million cases of typhoid fever, and 3 million cases of deaths world- wide each year due to Salmonella infections [5]. Salmonella typhimurium is one of the most common serovars associated with clinically reported salmonellosis in humans in most parts of the world, accounting for at least 15% of infections [2, 6]. S. typhimurium infects a wide range of animal hosts, including poultry, cattle, and pigs, and is termed ubiqui- tous which usually causes a self-limited gastroenteritis in humans [7]. he use of antibiotics is a major strategy and they are commonly used therapeutically and prophylactically to treat S. typhimurium infections in human and animal. However, increased antimicrobial resistance is exacerbating impact on public health worldwide, which leads to increased morbidity, mortality, and treatment costs [8, 9]. Scientiic studies showed that tylosin has low or no inhibitory efects on experimentally inoculated S. typhimurium in pigs [10, 11]. It was also reported that S. typhimurium illustrated resistance to ampicillin, chloramphenicol, streptomycin, sulphonamides, and tetracycline in 1980s, in the UK and later distributed extensively through Europe and North America. Additional resistance had attained to trimethoprim-sulfamethoxazole, ciproloxacin, and extended-spectrum cephalosporins within the 1990s [12]. Development of alternative antibacterial ther- apies is necessary to overcome this outbreak. Approximately 80% of the world’s inhabitants rely on traditional medicine for Hindawi Publishing Corporation BioMed Research International Volume 2014, Article ID 562173, 10 pages http://dx.doi.org/10.1155/2014/562173