Planta Med 2014; 80 - P1L120
DOI: 10.1055/s-0034-1394777

Antibiofilm activity of plant molecules against Pseudomonas aeruginosa and Staphylococcus aureus

A Borges 1, 2, MJ Saavedra 2, M Simões 1
  • 1LEPABE, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, s/n, 4200 – 465 Porto, Portugal
  • 2CECAV-Veterinary and Animal Science Research Center, Veterinary Science Department, University of Trás-os-Montes e Alto Douro, Apartado 1013, 5001 – 801 Vila Real, Portugal

In recent years, the resistance of pathogenic bacteria to current antibiotics has been increasingly documented. In most of the cases, this limited efficacy is related to the presence of biofilms [1]. These bacterial communities pose a critical problem in everyday life, causing many economic and health problems. Therefore, alternative sources of antimicrobial substances are required. Currently, plants are recognized as a source of unexplored chemical structures with high therapeutic potential. In this context, some natural compounds commonly found in plants, such as phenolics and isothiocyanates (ITCs), have several biological properties, including antimicrobial activity [2]. Considering their inhibitory properties, it is important to study their effects against bacterial biofilms with clinical interest. The purpose of this study was to evaluate the antibiofilm activity of two phenolic acids (gallic acid-GA and ferulic acid-FA) and two isothiocyanates (allylisothiocyanate-AITC and 2-phenylethylisothiocyanate-PEITC) at 1000 µg/mL, against important opportunistic pathogens, Pseudomonas aeruginosa and Staphylococcus aureus. Biofilm studies (prevention and control) were performed using a microtiter plate assay and the effect of phytochemicals were characterized in terms of biomass formation (crystal violet staining) and metabolic activity (alamar blue staining). The compounds assayed showed high potential to prevent and control the biofilms of the tested bacteria. In general, GA and AITC were more effective in biofilm prevention (removal/inactivation) than the FA and PEITC for both bacteria. The higher reduction in biomass was found for P. aeruginosa with GA. In terms of viability, all compounds promoted reductions higher than 68% for the biofilms tested. Biofilm prevention with GA and ITCs occurred at higher levels than the control. The overall results emphasize the potential of phytochemicals as emergent molecules to microbial growth control, including biofilms.

Keywords: Biofilm control, biofilm prevention, isothiocyanates, natural compounds, pathogenic bacteria, phenolic acids

References:

[1] Simões M, Bennett RN, Rosa EAS. Understanding antimicrobial activities of phytochemicals against multidrug resistant bacteria and biofilms. Nat Prod Rep 2009; 26: 74 – 757.

[2] Saavedra MJ, Borges A, Dias C, Aires A, Bennett RN, Rosa ES, Simões M. Antimicrobial activity of phenolics and glucosinolate hydrolysis products and their synergy with streptomycin against pathogenic bacteria. Med Chem 2010; 6: 174 – 183.