Quebecol Shows Potential to Alleviate Periodontal Tissue Damage and Promote Bone Formation in In Vitro Models

Quebecol is a polyphenolic compound initially isolated from Canadian maple syrup in 2011. Recently, our group demonstrated in a macrophage model that quebecol inhibits the secretion of pro-inflammatory cytokines and reduces the activation of the NF-κB transcription factor. In this study, we further explored the therapeutic potential of quebecol against periodontal disease, an inflammatory disorder of bacterial origin affecting tooth-supporting tissues. More specifically, the effects of this natural compound on matrix metalloproteinase (MMP) activity and macrophage secretion, as well as on the mineralization activity of osteoblasts (bone-forming cells), were investigated. Results showed that exposing lipopolysaccharide (LPS)-treated macrophages to quebecol led to a significant decrease in the secretion of MMP-8 and MMP-9. In addition, quebecol dose dependently inhibited the catalytic activity of MMP-9. Quebecol also enhanced the mineralization activity of osteoblasts. This study brought forward additional evidence to support the potential of quebecol as a nutraceutical agent against periodontitis.

A polyphenolic cinnamon fraction exhibits anti-inflammatory properties in a monocyte/macrophage model

Periodontal diseases are bacteria-induced inflammatory disorders that lead to the destruction of the tooth-supporting tissues. Active compounds endowed with a capacity to regulate the inflammatory response are regarded as potential therapeutic agents for the treatment of periodontal diseases. The aim of this study was to characterize the anti-inflammatory properties of a polyphenolic cinnamon fraction. Chromatographic and mass spectrometry analyses of the polyphenolic composition of the cinnamon fraction revealed that phenolic acids, flavonoids (flavonols, anthocyanins, flavan-3-ols), and procyanidins make up 9.22%, 0.72%, and 10.63% of the cinnamon fraction, respectively. We used a macrophage model stimulated with lipopolysaccharides (LPS) from either Aggregatibacter actinomycetemcomitans or Escherichia coli to show that the cinnamon fraction dose-dependently reduced IL-6, IL-8, and TNF-α secretion. Evidence was brought that this inhibition of cytokine secretion may result from the ability of the fraction to prevent LPS-induced NF-κB activation. We also showed that the cinnamon fraction reduces LPS binding to monocytes, which may contribute to its anti-inflammatory properties. Lastly, using a competitor assay, it was found that the cinnamon fraction may represent a natural PPAR-γ ligand. Within the limitations of this in vitro study, the cinnamon fraction was shown to exhibit a therapeutic potential for the treatment of periodontal diseases due to its anti-inflammatory properties.

Biocompatible combinations of nisin and licorice polyphenols exert synergistic bactericidal effects against Enterococcus faecalis and inhibit NF-κB activation in monocytes

Enterococcus faecalis is one of the bacterial species most frequently isolated from persistent endodontic and apical periodontal infections. The aim of the present study was to evaluate the synergistic antibacterial effects of nisin and selected licorice polyphenols (glabridin, licoricidin, licochalcone A) against planktonic and biofilm-embedded E. faecalis cells. The biocompatibility and anti-inflammatory properties of the nisin/licorice polyphenol combinations were also investigated. The lantibiotic bacteriocin (nisin), the two isoflavonoids (glabridin, licoricidin), and the chalcone (licochalcone A) efficiently inhibited the growth of E. faecalis, with MICs ranging from 6.25 to 25 µg/mL. Combining nisin with each licorice polyphenol individually resulted in a significant synergistic antibacterial effect. Following a 30-min contact, nisin in combination with either glabridin, licoricidin, or licochalcone A caused significant biofilm killing. The nisin/licorice polyphenol combinations had no cytotoxic effects (oral epithelial cells, gingival fibroblasts, and stem cells of the apical papilla), with the exception of nisin/glabridin, when used at their MICs. Lastly, we showed that nisin/glabridin, nisin/licoricidin, and nisin/licochalcone A inhibit NF-κB activation induced by E. faecalis in a monocyte model, suggesting that these combinations possess anti-inflammatory properties. The present study provides evidence that combinations of nisin and glabridin, licoricidin, or licochalcone A show promise as root canal disinfection agents.

Lobaric acid and pseudodepsidones inhibit NF-κB signaling pathway by activation of PPAR-γ

Herein we report the anti-inflammatory activity of lobaric acid and pseudodepsidones isolated from the nordic lichen Stereocaulon paschale. Lobaric acid (1) and three compounds (2, 7 and 9) were found to inhibit the NF-κB activation and the secretion of pro-inflammatory cytokines (IL-1β and TNF-α) in LPS-stimulated macrophages. Inhibition and docking simulation experiments provided evidence that lobaric acid and pseudodepsidones bind to PPAR-γ between helix H3 and the beta sheet, similarly to partial PPAR-γ agonists. These findings suggest that lobaric acid and pseudodepsidones reduce the expression of pro-inflammatory cytokines by blocking the NF-κB pathway via the activation of PPAR-γ.

Dibenzofurans and Pseudodepsidones from the Lichen Stereocaulon paschale Collected in Northern Quebec

Chemical investigation of the methanol extract of the lichen Stereocaulon paschale collected in Nunavik, Canada, led to the isolation and identification of two new dibenzofurans (1 and 3) and 11 known lichen metabolites. The structures of the new compounds were established by analysis of 1D and 2D NMR spectroscopic and high-resolution mass spectrometric data. Herein, the first isolation of ascomatic acid dibenzofuran derivatives (1-3) from a whole lichen organism is reported. In addition, some of the isolated metabolites showed antibacterial activity against the oral pathogens Porphyromonas gingivalis and Streptococcus mutans.

The Daiokanzoto (TJ-84) Kampo Formulation Reduces Virulence Factor Gene Expression in Porphyromonas gingivalis and Possesses Anti-Inflammatory and Anti-Protease Activities

Kampo formulations used in Japan to treat a wide variety of diseases and to promote health are composed of mixtures of crude extracts from the roots, bark, leaves, and rhizomes of a number of herbs. The present study was aimed at identifying the beneficial biological properties of Daiokanzoto (TJ-84), a Kampo formulation composed of crude extracts of Rhubarb rhizomes and Glycyrrhiza roots, with a view to using it as a potential treatment for periodontal disease. Daiokanzoto dose-dependently inhibited the expression of major Porphyromonas gingivalis virulence factors involved in host colonization and tissue destruction. More specifically, Daiokanzoto reduced the expression of the fimA, hagA, rgpA, and rgpB genes, as determined by quantitative real-time PCR. The U937-3xκB-LUC monocyte cell line transfected with a luciferase reporter gene was used to evaluate the anti-inflammatory properties of Daiokanzoto. Daiokanzoto attenuated the P. gingivalis-mediated activation of the NF-κB signaling pathway. It also reduced the secretion of pro-inflammatory cytokines (IL-6 and CXCL8) by lipopolysaccharide-stimulated oral epithelial cells and gingival fibroblasts. Lastly, Daiokanzoto, dose-dependently inhibited the catalytic activity of matrix metalloproteinases (-1 and -9). In conclusion, the present study provided evidence that Daiokanzoto shows potential for treating and/or preventing periodontal disease. The ability of this Kampo formulation to act on both bacterial pathogens and the host inflammatory response, the two etiological components of periodontal disease, is of high therapeutic interest.

Antibacterial and Anti-inflammatory Activities of Ppc-1, Active Principle of the Cellular Slime Mold Polysphondylium pseudo-candidum

The diisopentenyloxy quinolobactin derivative 3-methylbut-2-enyl-4-methoxy-8-[(3-methylbut-2-enyl)oxy] quinoline-2-carboxylate, also named as Ppc-1, has been initially isolated from the fruiting bodies of the cellular slime mold Polysphondylium pseudo-candidum. Given that few data are available in the literature concerning the biological properties of this compound, this study was undertaken to evaluate its antibacterial and anti-inflammatory properties. Ppc-1 exerted antibacterial activity on the Gram negative periodontopathogen Porphyromonas gingivalis, while it had no such effect on the other bacterial species tested. The antibacterial activity of Ppc-1 appeared to result from its ability to permeate the cell membrane. Using the U937-3xκB-LUC human monocytic cell line, Ppc-1 was found to dose-dependently inhibit the lipopolysaccharide-induced NF-κB activation, a signaling pathway that has been associated with inflammatory mediator secretion. In conclusion, Ppc-1, by exhibiting a dual mode of action including antibacterial and anti-inflammatory activities, may represent a promising targeted therapeutic agent for periodontal diseases.

Green tea extract and its major constituent epigallocatechin-3-gallate inhibit growth and halitosis-related properties of Solobacterium moorei

Background

Solobacterium moorei is a volatile sulfide compound (VSC)-producing Gram-positive anaerobic bacterium that has been associated with halitosis. The aim of this study was to investigate the effects of green tea extract and its major constituent epigallocatechin-3-gallate (EGCG) on growth and several halitosis-related properties of S. moorei.

Methods

A microplate dilution assay was used to determine the antibacterial activity of green tea extract and EGCG against S. moorei. Their effects on bacterial cell membrane integrity were investigated by transmission electron microscopy and a fluorescence-based permeability assay. Biofilm formation was quantified by crystal violet staining. Adhesion of FITC-labeled S. moorei to oral epithelial cells was monitored by fluorometry. The modulation of β-galactosidase gene expression in S. moorei was evaluated by quantitative RT-PCR.

Results

The green tea extract as well as EGCG inhibited the growth of S. moorei, with MIC values of 500 and 250 μg/ml, respectively. Transmission electron microscopy analysis and a permeabilization assay brought evidence that the bacterial cell membrane was the target of green tea polyphenols. Regarding the effects of green tea polyphenols on the S. moorei colonization properties, it was found that biofilm formation on EGCG-treated surfaces was significantly affected, and that green tea extract and EGCG can cause the eradication of pre-formed S. moorei biofilms. Moreover, both the green tea extract and EGCG were found to reduce the adherence of S. moorei to oral epithelial cells. The β-galactosidase activity of S. moorei, which plays a key role in VSC production, was dose-dependently inhibited by green tea polyphenols. In addition, EGCG at ½ MIC significantly decreased the β-galactosidase gene expression.

Conclusion

Our study brought evidence to support that green tea polyphenols possess a number of properties that may contribute to reduce S. moorei-related halitosis. Therefore, these natural compounds may be of interest to be used to supplement oral healthcare products.

The anthraquinone rhein exhibits synergistic antibacterial activity in association with metronidazole or natural compounds and attenuates virulence gene expression in Porphyromonas gingivalis

OBJECTIVE

Rhein is a major anthraquinone found in rhubarb root. As a continuation of our ongoing studies aimed to identify beneficial properties of this anthraquinone for periodontal disease, in this study, we investigated the ability of rhein to (i) exhibit antibacterial synergy towards the periodontopathogen Porphyromonas gingivalis when used in combination with metronidazole or polyphenols belonging to different families, and (ii) attenuate virulence factor gene expression in P. gingivalis.

METHODS

The minimal inhibitory concentrations (MIC) of compounds under investigation were determined by a broth microdilution assay. The synergistic effects of rhein in association with either metronidazole or polyphenols of various families were evaluated using the chequerboard technique to determine the fractional inhibitory concentration index (FICI). The effect of rhein on virulence factor gene expression in P. gingivalis was determined by quantitative RT-PCR.

RESULTS

Rhein showed a MIC of 2.5 μg/mL, which was similar to that of metronidazole. Except for the association with epigallocatechin-3-gallate that gave an additive effect, all the other combinations (licochalcone A, glabridin, myricetin, and metronidazole) resulted in synergistic effects. The strongest synergy was observed when rhein was used in association with myricetin (FICI=0.12) and licochalcone A (FICI=0.19). At a sub-MIC of rhein (0.5 μg/mL), a significant decrease in the expression of fimA, hagA, and hagB genes, which are involved in host colonization, was observed. Moreover, the expression of rgpA and kgp, two protease genes related to inactivation of host defense mechanisms, tissue destruction, and nutrient acquisition, was also down-regulated.

CONCLUSION

The data presented in our study indicate that rhein possessed antibacterial activity, which can be potentiated in combination with metronidazole or other polyphenols. In addition, rhein can impair the pathogenicity of P. gingivalis by reducing transcription of genes coding for important virulence factors.

The Kampo medicine Rokumigan possesses antibiofilm, anti-inflammatory, and wound healing properties

Periodontal diseases, which are inflammatory diseases of bacterial origin affecting the tooth-supporting tissues, are characterized by inflammation and destruction of gingival connective tissue and alveolar bone, and may lead to tooth loss. The aim of the study was to investigate Rokumigan, a Kampo Japanese traditional medicine made of six different plants, for its capacity to prevent biofilm formation by Fusobacterium nucleatum, to inhibit interleukin-6 (IL-6) and interleukin-8 (IL-8) secretion by mucosal cells, and to promote wound healing in a fibroblast model. Using a microplate colorimetric assay, Rokumigan prevented biofilm formation by F. nucleatum, while it had no effect on bacterial growth. Rokumigan inhibited IL-6 secretion in both epithelial cells and fibroblasts stimulated with lipopolysaccharide. However, it caused no significant inhibition of IL-8 secretion by both cell types. Rokumigan significantly increased proliferation and migration of gingival fibroblasts in a wound healing assay. In conclusion, the Kampo formulation Rokumigan, through suppression of biofilm formation by F. nucleatum, inhibition of IL-6 secretion by gingival epithelial cells and fibroblasts, and promotion of wound healing in a fibroblast model, may have potential application for periodontal diseases.

Pyrano-isoflavans from Glycyrrhiza uralensis with antibacterial activity against Streptococcus mutans and Porphyromonas gingivalis

Continuing investigation of fractions from a supercritical fluid extract of Chinese licorice (Glycyrrhiza uralensis) roots has led to the isolation of 12 phenolic compounds, of which seven were described previously from this extract. In addition to these seven metabolites, four known components, 1-methoxyerythrabyssin II (4), 6,8-diprenylgenistein, gancaonin G (5), and isoglycyrol (6), and one new isoflavan, licorisoflavan C (7), were characterized from this material for the first time. Treatment of licoricidin (1) with palladium chloride afforded larger amounts of 7 and also yielded two new isoflavans, licorisoflavan D (8), which was subsequently detected in the licorice extract, and licorisoflavan E (9). Compounds 1-9 were evaluated for their antibacterial activities against the cariogenic Streptococcus mutans and the periodontopathogenic Porphyromonas gingivalis. Licoricidin (1), licorisoflavan A (2), and 7-9 showed antibacterial activity against P. gingivalis (MICs of 1.56-12.5 μg/mL). The most potent activity against S. mutans was obtained with 7 (MIC of 6.25 μg/mL), followed by 1 and 9 (MIC of 12.5 μg/mL). This study provides further evidence for the therapeutic potential of licorice extracts for the treatment and prevention of oral infections.