In vitro anticariogenic effect of gallic acid against Streptococcus mutans

Abstract

Involvement of <em>Streptococcus mutans</em> in the pathogenesis of dental caries among human populations is well established. Here, we studied the effect of gallic acid, a naturally occurring polyphenol on certain cariogenic activities of <em>S. mutans</em>. Gallic acid inhibited the glycosyltransferase activity, a key enzyme of sucrose metabolism by 27-36% in <em>S. mutans. </em>Minimal inhibitory concentration (MIC) of gallic acid (136 μg/mL) inhibited the growth of <em>S.mutans</em> by 50%. About 0.4 mM of the polyphenol reduced biofilm formation by 40%, hydrophobicity 60% and acid production 36% by the organism under <em>in vitro</em> growth conditions. Fluorescence microscopy revealed that in absence of gallic acid, the cells were present as clumps, however in the presence of gallic acid (68 µg/mL), they were well segregated due to the inhibition of biofilm formation. The present findings suggest that gallic acid has cariostatic activity against <em>S. mutans</em>, which may have potential application in prevention of dental caries.