In-vitro antibacterial activity of hydroalcoholic extract of propolis against pathogenic bacteria

Propolis is a resinous substance produced by honey bee (apis mellifera l.) from the exudations of plants. propolis varies in composition due to change in climate and phytogeographical location. this study was designed to assess the in vitro antibacterial activity of locally available propolis against gram positive and gram negative bacteria. bee propolis samples were collected from local apiaries. hydroalcoholic extracts of propolis was prepared using different concentrations of ethanol (65%,80% and 95%),methanol (65%,80% and 95%) and water. all the extracts were assessed for antibacterial effects against staphylococcus (s.) aureus,bacillus (b.) subtilis and escherichia (e.) coli using disc diffusion assay. the minimum inhibitory concentrations (mic) were determined by measuring the optical density on spectrophotometer. the results showed highly significant variations (p<0.05) in antibacterial activities of propolis extracts used in this study. among all the extracts,ethanolic extract of propolis showed highly significant (p<0.05) effect at 65% concentration with 29.18±1.19mm zone of inhibition for s. aureus and 26.37±1.13mm for b. subtilis; whereas,22.19±0.61mm zone of inhibition was measured against e. coli. significant difference (p<0.05) was shown for mic values among the treatments with minimum value for 65% ethanolic extract of propolis followed by 65% methanolic extract while higher values were noticed for aqueous extract. in conclusion,65% ethanolic extract showed more antimicrobial activity against s. aureus among all the extracts; however,aqueous extract represented least inhibitory potential. due to rich phytochemistry,propolis could be used as an alternative source of natural antimicrobial agents.