| Aromatic plants are rich in essential oils with considerable antimicrobial properties. The
aim of this study was to investigate chemical composition, antimicrobial activity and
antioxidant properties of Melissa officinalis and Deracocephalum moldavica essential oils (EOs).
The identification of chemical constituents of the EOs was carried out using gas chromatography-mass
spectrometry analysis and antimicrobial activity of the EOs was evaluated by disc
diffusion assay as well as determination of minimal inhibitory concentration (MIC) and minimal
bactericidal concentration against four important food-borne bacteria: Salmonella typhimorium,
Escherichia coli, Listeria monocytogenes and Staphylococcus aureus. Antioxidant activity of the
EOs was also determined by 2,2-diphenyl-1-picrylhydrazyl, 2,2-azinobis 3-ethylbenzo thiazoline6-sulfonic
acid and β-carotene bleaching tests. The major compounds of D. moldavica were
geranial (28.52%), neral (21.21%), geraniol (19.60%), geranyl acetate (16.72%) and the major
compounds of M. officinalis EO were citronellal (37.33%), thymol (11.96%), citral (10.10%) and
β-caryophyllene (7.27%). The underlying results indicated strong antimicrobial effects of the
oils against tested bacteria. Staphylococcus aureus with the lowest MIC value (0.12 mg mL-1) for
both EOs was the most sensitive bacterium, although, antibacterial effect of M. officinalis EO was
stronger than D. moldavica. In addition, the results of the antioxidant activity showed that both
EOs had notable antioxidant properties. In conclusion, both EOs are appropriate alternatives as
potential sources of natural preservative agents with the aim of being applied in food industries. |