Characterization of the anti-Porphyromonas gingivalis compound in bilberry (Vaccinium myrtillus L.) and comparison with its analogs

Objectives

The bacterium Porphyromonas gingivalis is a major causative agent of periodontitis. In this study, the anti-P. gingivalis compound in bilberry (Vaccinium myrtillus L.) was identified and its activity was compared with that of its related analogs.

Methods

An acetone-soluble bilberry fruit extract was purified using silica gel column chromatography, and the minimum inhibitory concentrations (MICs) of the purified fractions were determined against P. gingivalis. After purification, mass spectrometry, nuclear magnetic resonance, and optical rotation analyses were performed to identify the anti-P. gingivalis compounds. Furthermore, cell assays were performed to assess the anti-P. gingivalis activity and cytotoxicity of the identified compounds. The activity of these compounds was compared with that of their pentacyclic triterpene analogs.

Results

The anti-P. gingivalis in bilberry extracts was identified as ursolic acid, a pentacyclic triterpene (PCT). The MIC of ursolic acid against P. gingivalis was between 6.25 and 12.5 μg/mL; it killed P. gingivalis within 4 h of treatment at these concentrations. However, it showed no cytotoxicity against gingival carcinoma Ca9-22 cells at the MIC. Ursane-type PCT, including ursolic acid and oleanane-type PCT, exhibited anti-P. gingivalis activity.

Conclusions

Ursolic acid found in bilberry fruit extract exhibits anti-P. gingivalis activity. Similar activity is observed in a class of PCTs with a common structure.