Antibacterial activity of mangosteen pericarp extract against cariogenic Streptococcus mutans

Objective The purpose of this study was to examine the antibacterial activity of extract from\nmangosteen pericarp against Streptococcus mutans, bacteria associated with dental plaque formation\nand caries development.\n\nMaterials and methods Bacterial strains used in this study were S. mutans ATCC 25175 and\nKPSK2. Antibacterial activity was expressed as minimum inhibitory concentration (MIC) and\nminimum bactericidal concentration (MBC). The rates at which bacteria were killed were also\ndetermined by exposure to the extract at 2x and 4x MBC for varying time periods.\n\nResults The extract was effective against both strains of S. mutans. The MIC and MBC for the\nstrain ATCC 25175 were both equal to 0.625 μg/ml. The respective values for the strain KPSK2\nwere 0.625 and 1.25 μg/ml. The MIC and MBC were comparable to those of chlorhexidine,\nan antiseptic commonly used in dental plaque control. Time-kill assays for the strain ATCC\n25175 showed that treatment with the extract at 2x MBC caused a significant decrease in viable\ncount (log10 colony forming units/ml) of almost one order of magnitude after 90 minutes. When the\nextract concentration was increased to 4x MBC, the viable bacterial count was reduced by almost\ntwo orders of magnitude in 60 minutes, and was further decreased to an undetectable level in\n90 minutes.\n\nConclusion Mangosteen pericarp extract possessed strong antibacterial activity against S. mutans.\nThese results suggest that the extract may be developed as a new agent for dental plaque control\nand caries prevention.