Antimicrobial Activity of Extracts of Two Native Fruits of Chile: Arrayan (Luma apiculata) and Peumo (Cryptocarya alba)

Arrayan and peumo fruits are commonly used in the traditional medicine of Chile. In this study, the concentration of the extracts halving the bacterial viability and biofilms formation and disruption of the drug-sensitive and drug-resistant strains ofStaphylococcus aureusandPseudomonas aeruginosawas determined. The chemical composition of extracts was analyzed by high-resolution liquid chromatography coupled with mass spectrometry (U-HPLC/MS). The arrayan extract (Inhibitory concentration IC(50)0.35 +/- 0.01 mg/mL) was more effective than peumo extract (IC(50)0.53 +/- 0.02 mg/mL) in the inhibition ofS. aureusplanktonic cells. Similarly, the arrayan extract was more effective in inhibiting the adhesion (S. aureusIC(50)0.23 +/- 0.02 mg/mL,P. aeruginosaIC(50)0.29 +/- 0.02 mg/mL) than peumo extracts (S. aureusIC(50)0.47 +/- 0.03 mg/mL,P. aeruginosaIC(50)0.35 +/- 0.01 mg/mL). Both extracts inhibited quorum sensing in a concentration-dependent manner, and the most significant was the autoinducer-2 type communication inhibition by arrayan extract. Both extracts also disrupted preformed biofilm ofP. aeruginosa(arrayan IC(50)0.56 +/- 0.04 mg/mL, peumo IC(50)0.59 +/- 0.04 mg/mL). However, neither arrayan nor peumo extracts disruptedS. aureusmature biofilm. U-HPLC/MS showed that both fruit extracts mainly possessed quercetin compounds; the peumo fruit extract also contained phenolic acids and phenylpropanoids. Our results suggested that both extracts could be used as natural antimicrobials for some skin and nosocomial infections.