In vitro antibacterial and antiadherence properties of flavonoid-rich extract of Pistacia atlantica hull against microorganisms involved in dental plaque

Natural products have recently undergone more thorough investigation for their potential in preventing oral disease, particularly plaque-related diseases such as dental caries. It is well known that Streptococcus mutans and other cariogenic bacteria are the major etiological agents in dental caries. We investigated the antibacterial effects of Pistacia atlantica subsp. kurdica, an Iranian species of the family of Anacardiaceae, to inhibit the growth and acid production of microorganisms involved in dental plaque. P. atlantica fruit-hull extract prepared by percolation method using 70% ethanol. A flavonoid-rich extract of Pistacia atlantica (FEPA) was prepared by adsorption on macroporous resin and desorption by ethanol. Total flavonoid content was determined according as the aluminum chloride colorimetric method. The growth inhibitory activity of FEPA was tested against Streptococcus mutans, S. salivarious, S. sobrinus, S. sanguis and Actinomyces viscosus. Total flavonoid content of FEHP was 789.2±2.9mg/g. The MIC value of the FEPA was 0.71–0.86mg mL^-1. In-vitro studies had shown that FEPA at concentrations of 10%, could inhibit strongly acid-producing ability of S. mutans and salivary glycolysis up to 5h post rinsing when compared to Listerine (a commercial mouthwash) control (P<0.05). Meanwhile 10% FEPA was 55% effective in inhibiting bacterial adherence, as shown by the low weight of accumulated S. mutans plaque to nichrome wire mesh, while Listerine tested was no better than the water control. In conclusion, the antiacidogenic effect of P. atlantica suggests that this material could be a useful source for the development of promising anticariogenic agents and led to the acceptance of traditional use of this medicinal plant.

Acknowledgements: 1. Tehran University of Medical Sciences and Pharmaceutical Sciences Research Center. 2. Mr. AS. Nasreldin Heidari