Atividade antimicrobiana do óleo essencial de Gaultheria procumbens: estudos in vitro e in vivo

Abstract

The pharmacological study of medicinal plants has been highlighted by the identification of new substances. Plant secondary metabolites are substances produced in response to stress, often related to attacks by herbivores, insects or phytopathogens. Based on these metabolites are extracted substances that present benefits to humans. These substances often have biological activity. In context, the study of Gaultheria procumbens also known as Wintergreen appears as an alternative. This plant is shrub-shaped, can reach 2 meters in height and is distributed throughout the northern hemisphere. However, for the elucidation of different aspects, many tests must be performed, including: toxicity, antimicrobial activity and antioxidant activity. Therefore, this study was developed to investigate the chemical constituents of G. procumbens essential oil, its cytotoxic and genotoxic efficacy, its biological activity against bacteria, mycobacteria and yeast, as well as its antioxidant potential. GC/MS-GC/FID chromatographic analysis demonstrated methyl salicilate (99.96%) and linalool (0.04%) as the major substances. From the toxicity tests performed on peripheral blood mononuclear cells (PBMCs), it was possible to observe among the tested concentrations (1.82 to 58.34 mg/mL) the safe concentrations for the use of G. procumbens essential oil, as cellular damage was observed in the PicoGreen and comet assays only at the highest concentrations. In addition to safe levels of use, the essential oil of G. procumbens and methyl salicilate were used for microdilution tests in broth to determine the minimal inhibitory concentration (MIC), minimal microbicidal concentration (MMC) and time-kill kinetics. The results showed efficacy against several microorganisms, mainly Aeromonas caviae (ATCC15468), Candida albicans (ATCC14053) and M. fortuitum (ATCC 6841) with MIC values ranging from 1.82 to 3.16 mg/mL and MMC values ranging from 3.64 to 14.58 mg/mL, confirmed through the time-kill kinetics. Following in vitro tests, infections in fish of the species Rhamdia quelen were performed with the inoculation of A. caviae, and subsequently the fish were treated with G. procumbens essential oil to obtain data on increased longevity of these infected animals. and potential antioxidant activity of the essential oil. From the obtained results, it was demonstrated an increase of the fish life perspective, besides being reported antioxidant activity through the spleen analysis of these animals. In our results, G. procumbens essential oil demonstrates relevant biological activity at non-toxic levels. In order to find an effective therapeutic alternative against microbial resistance, as future perspectives will be developed antibiofilm tests using the essential oil as treatment.