INTRODUCTION: Bacterial resistance to the use of antibiotics is a reality faced by the scientific community [1]. Essential oils are often involved in several defense mechanisms used by plants to combat pathogen attacks [2]. The species of Croton grewioides Baill, belonging to the Euphorbiaceae family, is an aromatic plant native to northeastern Brazil. Its essential oil has antimicrobial, antifungal, larvicidal activity, among others [3]. The search for natural products that modulate the effect of antibiotics would become a cheap and viable practice in combating resistant microorganisms. AIMS: To evaluate the modulating activity of Gentamicin and Amikacin containing the essential oil of C. grewioides on Gran (+) and Gran (-) bacteria. METHODOLOGY: To extract the essential oil of C. grewioides (OECG), the upper parts subjected to hydrodistillation by steam drag were used. For quantification and identification of the compounds, the techniques of Gas Chromatography coupled to Mass Spectrometry (GC/MS) and Gas Chromatography with a GC/FID flame ionization detector were used. For the antibacterial activity of OECG, multidrug-resistant bacteria such as Escherichia coli 06, Staphylococus aureus 10, Klebisiela pneumoniae KPC and Klebisiela pneumoniae BLSE were used. The determination of the minimum inhibitory concentration (MIC) was evaluated using the microdilution method [4]. To evaluate the modulating activity, the OECG MIC values were used as a basis for antibiotics from the aminoglycoside class Gentamicin and Amikacin [5]. RESULTS AND DISCUSSION: Chemical analysis of the essential oil of C. grewioides demonstrated the presence of ursol with 50.34%, methyl-eugenol with 19.39% and anisole with 10.99%. The MIC values of the bacteria used in the study were 1024 µg/mL in the bacteria S. aureus 10 and E. coli 06, 512 µg/mL in K. pneumoniae KPC and 256 µg/mL in K. pneumoniae BLSE. In modulation tests, the bacteria S. aureus 10 and E. coli 06 showed synergistic effects with the antibiotics Amikacin and Gentamicin. K. pneumoniae BLSE, on the other hand, showed a synergistic effect with Gentamicin and an antagonistic effect on Amikacin. K. pneumoniae KPC showed an antagonistic effect with Gentamicin and equivalence with Amikacin. These values are related to the major compound spoilol, which has antimicrobial activity [6] [7]. CONCLUSION: The essential oil of C. grewioides has pharmacological potential against antimicrobial resistance, presenting synergistic effects modulating the action of the antibiotics Amikacin and Gentamicin. More research into the molecular interaction of the majority component, the antibiotics and the microorganisms tested, is necessary to confirm the possibilities for developing new antimicrobial therapies. ACKNOWLEDGMENT: To the Natural Products Research Laboratory, the Universidade Regionaldo Cariri and the scholarship funding agencies FUNCAP and CNPQ.
Comissão Organizadora
Francisco Mendonça Junior
Pascal Marchand
Teresinha Gonçalves da Silva
Isabelle Orliac-Garnier
Gerd Bruno da Rocha
Comissão Científica
Ricardo Olimpio de Moura
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