Microbial control and quorum sensing inhibition by phenolic compounds of acerola (Malpighia emarginata)

Recently, phenolic compounds have been tested for their ability to inhibit bacterial communication known as quorum sensing. The objective of this study was to characterize acerola pulp (Malpighia emarginata) regarding its centesimal composition and mineral content as determined by Total Reflection X-Ray Fluorescence as well as to determine the total phenolic content and the antioxidant, antimicrobial and anti-quorum sensing activities of the phenolic extract obtained from the pulp. The centesimal and mineral content presented values in good agreement with those shown for fruits of the Malpighia generum. The total phenolic content for the fruit was 5848.74 ± 4.18 mg GAE/L. The antioxidant activity determined by the ABTS method was 127.18 ± 6.6 цМ Trolox/g of fruit and 112.02 ± 0.03 цМ Trolox/g of fruit in the DPPH assay, expressive values as compared to other fruits. The phenolic extract inhibited all the evaluated bacteria with minimal inhibitory concentrations ranging from 487.39 mg GAE /L to 1462.18 mg GAE /L of extract. Interestingly, in sub-MIC concentrations the phenolic extract of acerola did not interfere with bacterial growth, but inhibited quorum sensing controlled phenotypes such as violacein production in Chromobacterium violaceum, swarming motility in Aeromonas hydrophila and more importantly, biofilm formation in these bacteria and also in Serratia marcencens. The phenolic extract from acerola presents important bioactive properties including the newly described ability to inhibit quorum sensing in bacteria which can be further explored as a means to control bacterial activities in foods.