Biological activities of the essential oils and methanol extract of Origanum vulgare ssp. vulgare in the Eastern Anatolia region of Turkey

Abstract

Abstract The present study was conducted to evaluate the antimicrobial activities, antioxidant and properties of essential oils and methanol extracts of Origanum vulgare ssp. vulgare plants. The chemical composition of a hydrodistilled essential oil of O. vulgare ssp. vulgare was analyzed by a GC/MS system. A total 62 constituents were identified. Caryophyllene and spathulenol were found to be the main constituents, followed by germacrene-D and α-terpineol. Antioxidant activity was measured employing two methods namely, scavenging of free radical DPPH and the inhibition of linoleic acid oxidation by methanol extracts and the essential oil of O. vulgare ssp. vulgare . Antioxidant studies suggested that methanol extract behaved as a strong free radical scavenger providing IC 50 at only 9.9 μg/ml, whereas the oil showed weaker activity with IC 50 at 8.9 mg/ml. Total phenolic constituents based on gallic acid equivalents revealed the presence of total soluble phenolics in the extract as 220 μg/mg dry extract (22%, w/w) and, most probably, they are responsible for the radical scavenging activity of methanol extracts. Methanol extract was not effectively able to inhibit linoleic acid oxidation and only 32% inhibition was achieved at 2 mg/ml concentration, far below that of the positive control (butylated hyroxytoluene, BHT) at the same concentration. However, 2.2 mg/ml essential oil solutions provided 50% inhibition in the linoleic acid oxidation test system. The antimicrobial test results showed that the essential oil of O. vulgare ssp. vulgare had great potential of antimicrobial activity against all 10 bacteria, and 15 fungi and yeast species tested. In contrast, the methanol extract from aerial parts of O. vulgare plant showed no antimicrobial activity. The result may suggest that the essential oil O. vulgare ssp. vulgare possesses compounds with antimicrobial properties as well as antioxidant activity, and therefore can be used as a natural preservative ingredient in food and/or pharmaceutical industry.