The Antibacterial and Antibiofilm Activities of Resveratrol on Gram-positive and Gram-negative Bacteria

Abstract

Aim: Resveratrol (3,5,4’-trihydroxystilbene) shows antimicrobial activity against many pathogens. It has been detected that subinhibitory concentrations can reduce bacterial motility and interference with quorum sensing, lead to reduced bacterial toxin production, and inhibit biofilm formation. In this study, we aimed to investigate resveratrol’s antibacterial and antibiofilm activities on some Gram-positive and Gram-negative bacteria. Material and Method: The bacterial strains, including Staphylococcus aureus (ATCC-29213), Bacillus subtilis (ATCC6051), Escherichia coli (ATCC-25923), and Pseudomonas aeruginosa (ATCC-27853) were grown overnight in LB broth at 37°C in a humidified chamber. The resveratrol was dissolved in 1.5% of dimethyl sulfoxide (DMSO). Serial two-fold dilutions of the resveratrol, ranging from 16 to 0.5 mg/ml, were prepared in a 96-well plate. The microdilution method determined the minimum inhibitory concentration (MIC) for the resveratrol. Bacterial biofilm formation was assessed using the crystal violet assay. The agar gel diffusion assay was also performed to determine the antimicrobial activity. Results: In these assays, the resveratrol inhibited the growth of both Gram-positive and Gram-negative bacteria strains tested, with inhibition zone diameters ranging from 19.8 to 22 mm and MIC values of 4 mg/ml, confirming its antimicrobial properties. Concerning the effect of resveratrol on biofilm formation, an inhibition ranging from 24% to 99% on the total biofilm mass was achieved for all bacteria strains (Fig. 2 and Fig. 3). 16 mg/ml of resveratrol is the most effective dose for antibiofilm activity. Conclusion: Resveratrol has gained significant scientific and public attention not only for being a possible natural antimicrobial but also for its potential functional and therapeutic applications. Further studies should be planned to understand the molecular mechanism underlying resveratrol’s inhibitory effect, investigate the synergistic effects of resveratrol with antibiotics, and apply it in clinical practice.