Combined potential of copaifera officinalis oleoresin and chitosan against oral pathogens

Copaifera officinalis Oleoresin (COR) and Chitosan (CH) were combined to test the potential to inhibit oral bacteria. First, COR was analyzed by GC-MS to identify its main constituents and then Minimum Inhibitory Concentration (MIC) assays and Minimum Microbiocidal Concentration (MMC) of the compounds alone against 17 pathogens were performed. Sixteen primary compounds were identified in COR, but the major constituent was β-Caryophyllene (40.5%). COR showed MIC concentrations of 26.04 to 46.87 µg/mL and CH 0.1 mg/mL to 0.8 mg/mL. Second, the combination against oral bacteria strains was tested using a checkerboard test with the determination of Fractional Inhibitory Concentration (FIC) for synergistic effect, followed by the bacterial biofilm aggregation test using monospecies and mixed biofilm. The combination of COR and CH showed a synergistic effect for S. oralis (ATCC 10557) and an additive effect for the other strains tested, promoting bactericidal activity, as well as reducing the concentrations needed to cause bacterial inhibition. In addition, it showed good activity in inhibiting biofilm formation, with inhibition percentages close to Azithromycin. The results of this study highlight the synergistic potential of COR and CH combination as a promising strategy in the search for innovative antimicrobial therapies for infections related to oral bacterial biofilms.