Avaliação da composição química, atividade antibacteriana e antibiofilme do óleo essencial de Croton pluriglandulosus Carn. -Torres & Riina

Abstract

The United Nations says that antimicrobial resistance is one of the world's main health problems, intensified by the indiscriminate use of antibiotics and the unavailability of new antimicrobials. In addition, many infectious processes are associated with biofilms, which increase the resistance of pathogens. To combat antimicrobial resistance, new compounds are being studied, especially natural products such as essential oils, which have antimicrobial activities that have been well reported in the literature. The aim of this study was therefore to determine the chemical composition of the essential oil from the leaves of Croton pluriglandulosus and to evaluate its antibacterial and antibiofilm activity on gram-positive and gram-negative bacterial strains. The antibacterial activity was determined by evaluating the minimum inhibitory concentration and the minimum bactericidal concentration at concentrations of 10 to 0.156 mg/ml. Antibiofilm activity was assessed by quantifying biomass with crystal violet and by counting viable cells by enumerating colony-forming units. To determine the possible mechanisms of action, the biofilms treated with the essential oil were analyzed by Scanning Electron Microscopy and Confocal Laser Scanning Microscopy. The essential oil of C. pluriglandulosus showed minimum inhibitory concentration and minimum bactericidal concentration for S. aureus strains at concentrations of 10 and 5 mg/ml. About inhibition of biofilm formation, in general, all the strains showed significant reductions in biomass and number of CFUs when treated with C. pluriglandulosus essential oil, however, the S. aureus strains proved to be more sensitive. In mature biofilms, treatment with C. pluriglandulosus essential oil did not cause a reduction in biomass for most strains, except E. coli. However, it significantly reduced the number of colony-forming units, especially for S. aureus. The micrographs indicate that the antimicrobial action is directly linked to structural damage to the membranes, as observed for E. coli and S. aureus. The results indicate that the essential oil of C. pluriglandulosus is a promising antimicrobial agent with potential for treating infections caused by biofilms of S. aureus, S. epidermidis and E. coli.