Inhibition of Streptococcus mutans biofilm formation using extracts from Assam tea compared to green tea

• Assam tea showed stronger inhibition of biofilm formation than green tea.
• Galloylated catechins have strong inhibiting activities to the biofilm.
• Galloylated catechins were presented at a higher concentration in Assam tea.
• The biofilm inhibition was likely offset by the presence of pectin.
• Concentration of pectin was remarkably higher in green tea than in Assam tea.

ObjectiveStreptococcus mutans, a gram-positive oral bacterium, has been identified as one of the principal etiological agents of human dental caries. To clarify the nature of the difference anti-biofilm effect against S. mutans between Assam tea from Camellia sinensis var. assamica, partially fermented, and green tea from Camellia sinensis, non-fermented, active agents from the teas were purified.MethodsEffects of Assam tea and green tea samples on biofilm were assessed by using the conventional titer plate method and the human saliva-coated hydroxyapatite discs. The purification and identification of inhibitors were performed by using ultrafiltration with centrifugal filter devices and high performance liquid chromatography.ResultsAssam tea has stronger biofilm inhibition activity against S. mutans than green tea. A substance of <10 kDa in mass in Assam tea had a high concentration of galloylated catechins and a stronger biofilm inhibiting activity than green tea. In contrast, substances >10 kDa in mass from green tea included higher concentrations of polysaccharides composed of galacturonic acid, such as pectin, that enhance biofilm formation.ConclusionsThe higher concentrations of galloylated catechins in Assam tea may assist in prevention of dental caries, whereas in green tea, this mode of inhibition was likely offset by the presence of pectin. Purification of catechins in partially fermented Assam tea with lower-molecular-weight polysaccharide than pectin may be useful for developing oral care products such as toothpaste and oral care gel pastes.