Inhibitory effects of fruit berry extracts on Streptococcus mutans biofilms

Abstract

Dark‐colored fruit berries are a rich source of polyphenols that could provide innovative bioactive molecules as natural weapons against dental caries. High‐quality extracts of cranberry, blueberry, and strawberry, and a combination of the three berry extracts (Orophenol), were used to treat 24‐h‐old Streptococcus mutans biofilms. The grown biofilms were treated with the berry extracts at concentrations ranging from 62.5 to 500 μg ml−1. Treated biofilms were assessed for metabolic activity, acidogenicity, biovolumes, structural organization, and bacterial viability. The biofilms treated with the cranberry and Orophenol extracts exhibited the most significant reductions in metabolic activity, acid production, and bacterial/exopolysaccharide (EPS) biovolumes, while their structural architecture appeared less compact than the control‐treated biofilms. The blueberry extract produced significant reductions in metabolic activity and acidogenicity only at the highest concentration tested, without significantly affecting bacterial/EPS biovolumes or biofilm architecture. Strawberry extracts had no significant effects on S. mutans biofilms. None of the berry extracts were bactericidal for S. mutans. The results indicate that cranberry extract was the most effective extract in disrupting S. mutans virulence properties without significantly affecting bacterial viability. This suggests a potential ecological role for cranberry phenols as non‐bactericidal agents capable of modulating pathogenicity of cariogenic biofilms.

Annual review of selected scientific literature: A report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

“…They have widely varied mechanisms of action, ranging from the inhibition of cell growth, reduced acid production, inhibition of glucan synthesis, or alteration of cell adhesion properties. An interesting article that addressed natural products was presented by Philip et al 402 Researchers used extracts from dark-colored berries (cranberries, blueberries, and strawberries) and a combination of 3-berry extracts (orophenol) on 24-hour-old S. mutans biofilms. Different concentrations were tested.…”

Ecological approaches to dental caries prevention: Alteration of biofilms by natural products and casein-phosphopeptide-amorphous calcium phosphate

“…A low pH environment at the biofilm-tooth interface promotes enamel demineralization, leading to the clinical onset of dental caries. We had earlier shown that treating S. mutans biofilms with cranberry extracts at concentrations between 125-500 µg/mL resulted in significant reductions in metabolic activity and lactic acid production [Philip et al, 2019a]. The same cranberry extract showed inhibitory activity against dual-species S. mutans-C. albicans biofilms, reducing metabolism and acidogenicity, although higher concentrations (500-1000 µg/mL) were required for significant effects.…”

“…Cranberry polyphenols may have a number of advantages over other suggested cariostatic natural products. A comparison of three dark-coloured berries (cranberry, wild blueberry, and strawberry) showed that cranberry extracts had the greatest effects against S. mutans biofilm virulence properties [Philip et al, 2019a]. While tea (Camellia sinensis) also contains high levels of biologically active phenolic compounds, studies have shown cranberry polyphenols have the ability to effect a more powerful disruption of cariogenic virulence factors [Yoo et al, 2011].…”

“…as described previously. [Philip et al, 2019a] The saliva coated HA discs (s-HA) were then moved to a flat-bottomed 24-well microtiter plate (Costar 3526, Sigma-Aldrich, New York, NY, USA) containing 2 mL/well of the different cranberry extract concentrations and treated for 5 min. The lid with the pre-treated s-HA discs was then gently shaken to remove any excess of treatment/control solutions and transferred to a 24-well plate containing 2 mL/well of the microbial inoculum and incubated at 37°C in an orbital shaker at 80 rpm.…”

“…We have recently demonstrated that a highly-purified polyphenol-rich cranberry extract was able to significantly disrupt acidogenicity, metabolic activity, EPS/microbial biovolumes and structural organisation of S. mutans biofilms, without affecting bacterial viability [Philip et al, 2019a]. Specific cranberry flavonoids, especially the A-linked proanthocyanidins (A-PACs), have been shown to be potent inhibitors of bacterial glycolysis and GtfB-mediated glucan synthesis in S. mutans biofilms and were shown to prevent dental caries development in vivo [Duarte et al, 2006;Gregoire et al, 2007;Koo et al, 2010;.…”