Extratos de casca de jabuticaba: compostos fenólicos e atividade antibacteriana

Abstract

Jabuticaba is a native fruit from Brazil, presents elevated contents of phenolic compounds, concentrated on the peal, and can be explored and exploited due to the benefits provided by these compounds, be it in the food and/or pharmaceutical industry, promoting its economic valorization. Therefore, in this work, we identified and quantified the phenolic compounds and evaluated the antibacterial activity of different extracts obtained from the jabuticaba peal flour (JPF). The phenolic compounds were extracted using four solvents and different forms of extraction: acetone 70% in repose for 2 hours, in the proportion of 1:10 (m/v); water under agitation, in the proportion of 1:15 (m/v); acidified ethanol under agitation, in the proportion of 1:15 (m/v) and methanol 50% under reflux, in the proportion of 1:50 (m/v), denominated, respectively, acetonic, aqueous, ethanolic and methanolic extract. These extracts were used to evaluate the antimicrobial activity by means of the agar cavity diffusion technique, in the concentrations of 250, 125, 62.5, 31.25, 15.62, 7.81, 3.90 and 0 µg mL -1 , using microorganisms Escherichia coli ATCC 11229, Salmonella cholerasuis ATCC 6539, Pseudomonas aeruginosa ATCC 15442, Staphylococcus aureus ATCC 6538 and Listeria monocytogenes ATCC 19117. For the concentration of 0 µg mL -1 , we inoculated 10 µL of distilled water (negative control) and, as comparison pattern, we inoculated 10 µL of the 100 µg mL -1 solution of the chloramphenicol antibiotic (positive control). The ethanolic extract presented higher phenolic compound extraction, followed by the methanolic extract. In relation to the antibacterial activity, none of the tested extracts presented growth inhibition for bacteria E. coli and S. cholerasuis. For P. aeruginosa, the minimum inhibitory concentration (MIC) for all extracts was of 250 µg mL -1 . For bacteria S. aureus, the ethanolic extract presented higher inhibition with MIC of 31.25 µg mL -1 , aqueous and methanolic extracts presented MIC of 62.5 µg mL -1 , while the acetonic extract presented inhibition only in the concentration of 250 µg mL -1 . For L. monocytogenes, the methanolic extract registered higher inhibition halo with MIC of 31.25 µg mL -1 , followed by ethanolic and aqueous extracts, which presented MIC of 62.5 µg mL -1 . The acetonic extract registered lower growth inhibition wit MIC of 125 µg mL -1 . Thus, these results suggest potential application of the ethanolic and methanolic extracts of the JPF as source of antibacterial substances against bacteria S. aureus and L. monocytogenes, and can be explored by food and pharmaceutical industries.