INFLUENCE OF RED WINE GRAPE PHENOLIC EXTRACTS ON GLUCOSYLTRANSFERASE ACTIVITY, ACIDOGENICITY, AND BIOFILM FORMATION OF STREPTOCOCCUS MUTANS.
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Wine grapes are rich sources of potentially bioactive polyphenols. However, phenolic content is variable depending on grape variety, and may be modified during vinification. In this study, we investigated the influence of phenolic extracts from Vitis vinifera (Cabernet Franc and Pinot noir), V. Labrusca (Concord), and Vitis hybrids (Baco noir and Noiret) grapes on several virulence properties of Streptococcus mutans a well-known cariogenic bacterium. Grape phenolic extracts were prepared from whole fruit (WF) and fermented pomace (FP). The anthocyanin and flavan-3-ol content were variable depending on variety and type of extract (WF vs. FP). Nevertheless, all extracts inhibited the activity of GTF B between 60-80% at concentrations as low as 31.2 ug/ml; GTF B synthesizes insoluble glucans, which are critical for the formation, bulk and structural integrity of biofilms. Furthermore, the glycolytic pH-drop by S. mutans cells was inhibited by the extracts without affecting bacterial viability, an effect that can be attributed to partial inhibition of F-ATPase by the extracts (30-65% inhibition at 125 ug/ml). In general, phenolic extracts from V. vinifera were more effective than those from Vitis hybrids. The biological activity of FP was either as effective as or significantly better than WF extracts. The most effective extracts were examined for their ability to disrupt biofilm development by S. mutans using a saliva-coated hydroxyapatite biofilm model. Biofilms were treated for 1 minute twice daily with phenolic extracts from FP of Cabernet Franc and Baco noir. Biofilms treated with the extracts (at 1 mg/ml) resulted in significantly lower amounts of extracellular insoluble polysaccharides than those treated with vehicle control (P<0.01), which agrees well with the GTF B inhibition data. The reduction of insoluble polysaccharides production is highly relevant because they are the main components of the extracellular matrix of biofilms, and are associated with the pathogenesis of dental caries. Overall, the phenolic extracts, especially from pomace, are effective against specific virulence attributes of S. mutans and can disrupt the synthesis of extracellular polysaccharide matrix of biofilms. Fermented pomace could be a potential source for extraction of bioactive compounds for prevention or reduction of oral diseases, such as dental caries.
grape, streptococcus mutans, polyphenols, glucosyltransferases, ATPase, biofilms
dissertation or thesis