Objectives: To determine the cytotoxicity and proliferation of Thai propolis extracts on the human dental pulp cells in vitro.
Methods: Raw propolis was obtained from Khon Kaen province. The phenolic and flavonoid content was determined by the Folin-Ciocalteau colorimetric and aluminum chloride colorimetric method, respectively. After extraction of propolis using 100% ethanol then 1,000, 100, 10 and 1 µg/ml of propolis extracts were prepared by dissolving in dimethyl sulfoxide (DMSO). Pulp cells obtained from healthy premolars were cultured in Dulbecco’s Modified Eagles medium (DMEM) supplement with 10% fetal bovine serum at 37oC in 5% CO2. Cytotoxicity and proliferation effects at 6, 12, 24 and 72 were evaluated using an Alamar blue assay and a methylene blue assay respectively. Analysis of the difference of cytoxicity and proliferation inside group were performed by One-way ANOVA.
Results: Thai propolis has high phenolic and flavonoid compound which the average value was 0.078 mg gallic acid/g and 136 mg quercetin/g respectively. Aliquots of 10 and 1 µg/ml. propolis solution at 6, 12, 24 and 72 hours demonstrated no cytotoxicity compared with others concentrations. Methylene blue assay showed that pulp cells treated with Thai propolis at a concentration of 5,000 µg/ml significantly increased in cells number at every duration.
Conclusions: From the limitation of this study, Thai propolis at low concentration (5,000 µg/ml.) is a biocompatible substance that stimulates human dental pulp cell proliferation.