Antibacterial, antibiofilm, and antivirulence potential of the main diterpenes from Copaifera spp. oleoresins against multidrug-resistant bacteria.

To evaluate the antibacterial, antibiofilm and antivirulence potential of the main diterpenes from Copaifera spp. oleoresins against multidrug-resistant (MDR) bacteria. Antimicrobial assays included determination of the Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC), Minimum Inhibitory Concentration of Biofilm (MICB50 ), as well as synergistic and antivirulence assays for eight diterpenes against MDR. The tests revealed that two diterpenes (named 1 and 5) showed the best results, with MIC and MBC between 12.5 and 50 μg/mL against most MDR bacteria. These diterpenes exhibited promising MICB50 in concentration between 3.12-25 μg/mL but showed no synergistic antimicrobial activity. In the assessment of antivirulence activity, diterpenes 1 and 5 inhibited only one of the virulence factors evaluated (Dnase) produced by some strains of S. aureus at subinhibitory concentration (6.25 μg/mL). Results obtained indicated that diterpenes isolated from Copaifera oleoresin plays an important part in the search of new antibacterial and antibiofilm agents that can act against MDR bacteria.