Resveratrol Oligomers Inhibit Biofilm Formation of <i>Escherichia coli</i> O157:H7 and <i>Pseudomonas aeruginosa</i>

Biofilm formation is closely related to bacterial infection and is also a mechanism of antimicrobial resistance. Hence, the antibiofilm approach provides an alternative to an antibiotic strategy. In this study, the antibiofilm activities of resveratrol (<b>1</b>) and five of its oligomers, namely, ε-viniferin (<b>2</b>), suffruticosol A (<b>3</b>), suffruticosol B (<b>4</b>), vitisin A (<b>5</b>), and vitisin B (<b>6</b>), were investigated against enterohemorrhagic <i>Escherichia coli</i> O157:H7 and <i>Pseudomonas aeruginosa</i> PA14. Vitisin B (<b>6</b>), a stilbenoid tetramer, was found to inhibit biofilm formation by the two bacteria the most effectively and at 5 μg/mL inhibited <i>E. coli</i> O157:H7 biofilm formation by more than 90%

Inhibition of Pseudomonas aeruginosa and Escherichia coli O157:H7 Biofilm Formation by Plant Metabolite ε‑Viniferin

Pathogenic biofilms are associated with persistent infection due to their high resistances to diverse antibiotics. Pseudomonas aeruginosa infects plants, animals, and humans and is a major cause of nosocomial diseases in patients with cystic fibrosis. In the present study, the antibiofilm abilities of 522 plant extracts against <i>P. aeruginosa</i> PA14 were examined. Three <i>Carex</i> plant extracts at a concentration of 200 μg/mL inhibited <i>P. aeruginosa</i> biofilm formation by >80% without affecting planktonic cell growth. In the most active extract of Carex pumila, resveratrol dimer ε-viniferin was one of the main antibiofilm compounds against <i>P. aeruginosa</i>. Interestingly, ε-viniferin at 10 μg/mL inhibited biofilm formation of enterohemorrhagic Escherichia coli O157:H7 by 98%. Although <i>Carex</i> extracts and <i>trans</i>-resveratrol are known to possess antimicrobial activity, this study is the first to report that <i>C. pumila</i> extract and ε-viniferin have antibiofilm activity against <i>P. aeruginosa</i> and <i>E. coli</i> O157:H7

Diverse plant extracts and <i>trans</i>-resveratrol inhibit biofilm formation and swarming of <i>Escherichia coli</i> O157:H7

<div><p>Infection with enterohemorrhagic <i>Escherichia coli</i> O157:H7 (EHEC) is a worldwide problem. Of the 498 plant extracts screened against EHEC, 16 inhibited the formation of biofilm of EHEC by >85% without inhibiting the growth of planktonic cells, and 14 plant extracts reduced the swarming motility of EHEC. The most active extract, <i>Carex dimorpholepis,</i> decreased swimming and swarming motilities and curli formation. Transcriptional analyses showed that the extract of <i>C. dimorpholepis</i> repressed curli genes, various motility genes, and AI-2 quorum sensing genes, which was corroborated by reduction in the production of fimbria, motility, and biofilm by EHEC. <i>Trans</i>-resveratrol at 10 μg ml⁻¹ in the extract of <i>C. dimorpholepis</i> was found to be a new anti-biofilm compound against EHEC, but importantly, the extract of <i>C. dimorpholepis</i> and <i>trans</i>-resveratrol did not inhibit the fomation of biofilm in four commensal <i>E. coli</i> strains. Furthermore, the extract of <i>C. dimorpholepis</i> decreased the adhesion of EHEC cells to human epithelial cells without affecting the viability of these cells.</p></div