Antimicrobial activity of Bulgarian white oregano essential oils and ethanol extracts

The chemical composition of ethanol extracts from wild and cultivated Bulgarian white oregano (Origanum heracleoticum L.) was determined. It was found that the aromatic compounds are the dominant group in the extracts of wild and cultivated white oregano – 89.75% in both extracts. The main components are carvacrol (70.97%) in the extract of wild oregano and carvacrol (60.47%) and thymol (8.55%) in the extract of cultivated oregano. The antimicrobial activity of aromatic products of Bulgarian white oregano was studied. The antimicrobial activity of the essential oils and ethanol extracts of oregano was determined against bacteria, which are found to be human pathogenic or food spoilage microorganisms – Staphylococcus aureus, Listeria monocytogenes and Escherichia coli ATCC 25922. Both the essential oils and the extracts showed antimicrobial activity against the tested microorganisms, more significant in the wild species, probably due to the high content of carvacrol. Gram-negative bacteria Escherichia coli showed resistance to the extracts, but were affected by the essential oils, the diameters of the zones of inhibition being comparable to those of the antibiotics Gentamicin and Tobradex. The results obtained suggest a potential application of these oils in preventing human pathogenesis and food spoilage due to microorganism growth.