Abstract

In vitro antibacterial activity of ethanol, ethyl acetate and acetone extract from Clinopodium vulgare and their synergistic interaction with gentamicin and cephalexin were researched. Antibacterial efficacy of the extracts was defined by determining minimum inhibitory concentrations (MIC) using microdilution method. The values were in the range from 0.625 to >20 mg/ml. The most sensitive bacteria were gram-positive bacteria: Staphylococcus aureus ATCC 25923 and Bacillus subtilis. Herb-drug interactions tested by checkerboard method and expressed as fractional inhibitory concentration (FIC) index showed indifferent and synergistic effects. Synergism was observed in relation to B. subtilis and Klebsiella pneumoniae. In the presence of sub-inhibitory concentrations (1/4 and 1/8 MIC) of the extracts, the activity of gentamicin and cephalexin was increased up to 16-fold. The highest amount of phenols and flavonoids had ethyl acetate extract while the lowest amount was measured for acetone extract.

Key words: Clinopodium vulgare, antibacterial activity, plant extracts, herb-drug interaction, total phenol, flavonoid content.