Antioxidant Activity of the Essential Oil and Methanolic Extract of Teucrium orientale (L.) subsp. taylori (Boiss.) Rech. f.

This study was designed to examine the chemical composition and in-vitro antioxidant activity of the essential oil and methanolic extract of Teucrium orientale subsp. taylori. The GC and GC–MS analysis of the essential oil resulted in determination of 40 components representing 96.4% of the oil. The major constituents of the oil were linalool (28.6%), caryophyllene oxide (15.6%), 1,8-cineol (4.5%), β-pinene (8.7%), 3-octanol (9.5%), β-caryophyllene (7.3%), and germacrene-D (4.1%). Antioxidant activities of the samples were determined by two different tests, namely DPPH and β-carotene- linoleic acid assay. In DPPH system, the weakest radical scavenging activity was exhibited by the non-polar sub fraction of methanolic extract (237.40 ± 2.1 μg/mL). Antioxidant activity of the polar sub fraction of methanolic extract was superior to all samples tested, showing an EC50 value of 61.45 ± 0.5 μg/ mL. The inhibition capacity (%) of the polar sub fraction of methanolic extract (95.21% ± 1.3) was found to be the strongest and almost equal to the inhibition capacity of the positive control BHT (94.9% ± 1.1). The amount of the total phenolics was the highest in the polar subfraction, i.e. 370 μg/mg of the dry extract (37%). A positive correlation was observed between the antioxidant activity and the total phenolics of the extracts.