ABSTRACT
Dental plaque (DP) is found on the surface of teeth and comprises a community of microorganisms that form a structured biofilm. Bacteria present in DP are potential periodontal pathogens when there is an imbalance in the healthy oral environment, and are precursors of periodontal disease (PD). In dogs, the treatments, such as mechanical removal, are difficult and expensive to apply. Therefore, in order to seek new therapeutic alternatives to control dental plaque in dogs, Brazilian red propolis ethanol extract (RPEE) was tested to evaluate its antibacterial effect on bacteria isolated from DP of dogs without PD. DP was collected from the supragingival dental surfaces of 10 dogs. Bacterial isolates of DP were identified by PCR and sequencing of 16S rDNA gene. The RPEE was obtained using the ultrasound ethanol extraction technique, and the chemical composition was obtained by HPLC-DAD and UV-spectrophotometry. In total, 29 different bacteria belonging to five genera were identified. Formononetin, biochanin A, liquiritigenin and daidzein were the major constituents of the RPEE. The cytotoxic effect showed cell viability after 24 h above 50 % at all concentrations evaluated. The minimum inhibitory concentration was between 37.5 and 150.0 µg/mL for all bacterial isolates. The minimal bactericidal concentration was between 150 and 1200 µg/mL for Gram-positive and 300-1200 µg/mL for Gram-negative bacteria. The results are promising and suggest that RPEE has significant antibacterial potential against the bacteria present in the DP of healthy dogs. Although further studies are still needed, the results suggest RPEE might be safely used in the prevention of periodontal disease.