EXPLORING ANTIMICROBIAL ACTIVITY OF HOREHOUND, Marrubium peregrinum L. EXTRACTS

Antimicrobial activity of methanol, acetone and ethyl acetate extracts from whole herb of Marrubium peregrinum L. (Lamiaceae) were investigated in this study. Horehound, a perennial plant, was collected from the region of Suva Planina Mt. in eastern Serbia. Testing was preformed by microdilution method and minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC) have been determined. Testing was conducted against 22 microorganisms, of which 15 strains of bacteria and 7 species of fungi. The strongest antimicrobial activity was detected on G+ bacteria while the activities on other species were moderate. The activity of tested extracts varied depending on the species and type and concentration of the extract. The comparative analyses showed that the most active was methanol extract (MIC from 0.3125 mg/ml to 40 mg/ml) followed by ethyl acetate (MIC from 0.0781 mg/ml to 40 mg/ml) and acetone extract (MIC from 0.1563 mg/ml to 40 mg/ml). The most sensitive bacteria were Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853 and especially ethyl acetate extract on Bacillus subtilis (MIC 0.0781 mg/ml). The best antifungal effect demonstrated methanol extract on Aspergillus niger ATCC 16404 (MIC 0.625 mg/ml). The antimicrobial properties of Marrubium peregrinum L. are insufficiently tested. Overall, extracts showed potential for further investigation and use.