Antimicrobial Activity of , , , Extracts and Rhein against .

Novel plant-derived antimicrobials are of interest in dentistry, especially in the treatment of periodontitis, since the use of established substances is associated with side effects and concerns of antimicrobial resistance have been raised. Thus, the present study was performed to quantify the antimicrobial efficacy of crude plant extracts against , a pathogen associated with periodontitis. The minimal inhibitory concentrations (MICs) of leaf, leaf, root and root extracts were determined by broth microdilution for ATCC 33277 according to CLSI (Clinical and Laboratory Standards Institute). The MICs for the , and extracts ranged from 64 mg/L to 1024 mg/L. The lowest MIC was determined for an ethanolic extract with 4 mg/L. The MIC for the anthraquinone rhein was also measured, as the antimicrobial activity of root extracts can be partially traced back to rhein. Rhein showed a remarkably low MIC of 0.125 mg/L. However, the major compounds of the root extract were not further separated and purified. In conclusion, root extracts should be further studied for the treatment of periodontitis.