Antimicrobial activity of aqueous, alcoholic and buffer extracts of honey-bee propolis on oral-intestinal bacteria

Propolis plays an antibacterial, anti-fungal, anti-parasitic, antioxidant, anti-inflammatory, anti-caries role due to its plant-derived compounds such as polyphenols and proteins such as 10-HDA. It has long been a therapeutic role for diseases, especially infections. In this study antimicrobial activity of alcoholic, aqueous and buffer extract of propolis, on oral bacteria including Streptococcus mutans, Streptococcus epidermidis, Staphylococcus aureus, and gastro-intestinal bacteria including Streptococcus salivarius and Escherichia coli measured using micro broth dilution test for assessing of minimum inhibitory concentration (MIC) and disk diffusion test for assessing of diameter of inhibition zone. The MIC did not differ significantly between the three alcoholic, aqueous and buffer extracts, i.e., the effect of the solvents on the solubility of the antibacterial compounds was approximately the same (P > 0.05). The most resistant gram-positive bacterium to alcoholic and buffer extract, Streptococcus mutans and the most resistant to all extracts, Escherichia coli, were reported. There was no significant difference between the bacterial resistance in the aqueous extract of propolis (P> 0.05). In the disk diffusion test, increasing the concentration of extracts had a significant effect on the bacterial killing rate and was identified as the most susceptible bacterium to the extracts Staphylococcus epidermidis and the most resistant bacterium Staphylococcus aureus. The bacteria were also more sensitive to buffer extract.