The aim of this study was to investigate antimicrobial effect of oleanolic acid (OA), ursolic acid (UA), and sophoraflavanone G against Enterococcus faecalis and Propionibacterium acnes, which are the major causative bacteria of endodontic infections. The antimicrobial activity was evaluated by the minimal inhibitory concentration (MIC). The data showed that the OA, UA, and sophoraflavanone G had antimicrobial effect on all the strains use in the study with 16-64 µg/ml, 8-64 µg/ml, and 1-8 µg/ml of MIC values, respectively. These results indicate that OA, UA, and sophoraflavanone G could be useful in the development of antiseptic solution for washing the root canal in endodontic treatments.

In general, oleanolic acid (OA) and ursolic acid (UA) have antimicrobial effect against Gram-positive bacteria but not Gram-negative bacteria whereas sophoraflavanone G has antimicrobial activity against both bacterial types. However, the antimicrobial effects of OA, UA, and sophoraflavanone G against periodontopathogens have not been studied to any great extent. The aim of this study was to investigate antimicrobial effect of OA, UA, and sophoraflavanone G against 15 strains (5 species) of oral Gram-negative bacteria, which are the major causative bacteria of periodontal disease. The antimicrobial activity was evaluated by minimal inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) determinations. OA and UA showed antimicrobial effects against all of the Porphyromonas gingivalis strains tested and also Prevotella intermedia ATCC 25611T. Interestingly, P. intermedia ATCC 49046 showed greater resistance to OA and UA than P. intermedia ATCC 25611T. In contrast, sophoraflavanone G had antimicrobial activity against all strains, with MIC and MBC values below 32 μg/ml, except Aggregatibacter actinomycetemcomitans. These results indicate that sophoraflavanone G may have potential for use in future oral hygiene products such as dentifrices and gargling solution to prevent periodontitis.