Chemical composition, antimicrobial activity and antioxidant capacity of some medicinal and aromatic plant extracts

In this study, the chemical composition, antimicrobial activity and antioxidant capacity of essential oils obtained from oregano (Origanum onites L.), sage (Salvia triloba L.), mint (Mentha piperita L.), and laurel (Laurus nobilus L.) were determined. The essential oil components were identified by gas chromatography (GC) analysis. The antimicrobial activity of the oils was determined against some pathogenic and lactic acid bacteria using a disc diffusion method. The total antioxidant capacity was evaluatedspectrophotometrically as α-tocopherol equivalent. The GC analysis showed that the major constituents of the oils were monoterpene hydrocarbons and phenolic monoterpenes, but the concentration of these compounds varied greatly among the oils examined. The main components of the essential oil were carvacrol, menthol, 1-8 cineole, thujon, camphor and menthone. The results of the antimicrobial assay showed that majority of essential oils showed varied levels of antimicrobial activity against the tested indicator strains. Also, all essential oils exhibited antioxidant effect on oils used in the experiment. The results of this study confirmed the possibility of using some essential oils in food as preservation systems for growth of foodborne bacteria, improving antioxidant properties and extend the shelf-life of processed foods. Key words: Essential oil, chemical composition, antimicrobial activity, antioxidant capacity, medicinal and aromatic plants