Synergistic Effect and Antiquorum Sensing Activity of Nymphaea tetragona (Water Lily) Extract

Salmonellosis is a common and widely distributed food borne disease whereSalmonella typhimuriumis one of the most important etiologic agents. The purpose of this study was to investigate the antimicrobial activity ofNymphaea tetragonaalone and in combination with antibiotics againstS. typhimurium. It also aimed to assess the plant for quorum sensing inhibition (QSI) activity and to identify the bioactive compounds. The antibacterial activities of the extract were assessed using broth microdilution method. Disk agar diffusion method was employed to determine the QSI and bioactive compounds were identified by GC-MS analysis. Ethyl acetate fraction ofN. tetragonaextract (EFNTE) demonstrated good antimicrobial activity (MIC 781 μg/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 againstS. typhimurium. Among all extracts, EFNTE and butanol fraction more significantly inhibited pigment production ofC. violaceum. Polyphenols were identified as major compound of EFNTE and butanol fraction. These results indicate that combination amongN. tetragonaextract and antibiotics could be useful to combat drug-resistanceSalmonellainfections and polyphenols are promising new components fromN. tetragonathat warrant further investigation as a candidate anti-Salmonellaagent and quorum sensing inhibitor.