Antioxidant, antimicrobial and anti-quorum sensing activities of Rubus rosaefolius phenolic extract

• Determination of centesimal composition and trace elements.
• Determination of the phenolic compounds concentration by the Folin–Ciocalteu method.
• Evaluation of antioxidant activity by the ABTS and DPPH methods.
• Determination of antimicrobial activity by MIC and plate diffusion assay.
• Quorum sensing inhibition determined through phenotypic evaluations.

Phenolic compounds are plant secondary metabolites that present many biological effects including antioxidant and antimicrobial activities. Studies have shown that these compounds can also inhibit quorum sensing bacterial communication. The aim of this study was to characterize the centesimal composition, mineral and phenolic content, to determine the antioxidant and antimicrobial effect as well as the inhibition of quorum sensing by the phenolic extract obtained from wild strawberry (Rubus rosaefolius). Centesimal composition and minerals were in the range expected for fruits of the Rubus generum, even though Fe and Zn presented higher levels. The phenolic content was 5902.89 mg GAE/L, also approaching the levels found for fruits of Rubus sp. The antioxidant activity determined through the ABTS method was 162.4 ± 5.6 and 120.8 ± 1.5 μM Trolox/g of fruit in the DPPH assay, indicating an elevated potential for ABTS and medium potential for DPPH method. The phenolic extract was able to inhibit all the evaluated bacteria presenting MICs in the range of 491.90–1475.74 mg GAE/L. In sub-MIC concentrations, the phenolic extract inhibited all the phenotypes typically regulated by quorum sensing in bacteria, including violacein production, swarming motility and biofilm formation. The phenolic extract of R. rosaefolius presented antioxidant, antimicrobial and anti-quorum sensing activities which are in agreement with previous studies linking phenolic compounds to these properties.