Chemical composition of essential oil and antioxidant activity of leaves and stems of Phlomis lurestanica

Abstract

Essential oils from leaves and stems of Phlomis lurestanica at the flowering stage were extracted by hydrodistillation. The essential oils were analyzed using Gas Chromatography and Gas Chromatography-Mass Spectrometry. Twenty-eight and twenty-five compounds were identified in the stems and leaves, respectively. The main compounds of stems were α-pinene (12.40%), γ-cadinene (10.92%), and γ-elemene (6.46%). Hexadecane (8.97%), 2-dodecnenal (6.57%), and heptadecane (6.32%) were the major constituents in the essential oils of the leaves. The methanol extracts of stems and leaves were evaluated for their antioxidant properties using 2,2-diphenyl-1-picrylhydrazyl and β-carotene/linoleic acid tests. In the 2,2-diphenyl-1-picrylhydrazyl assay, the leaves (IC50 = 1168.9 µg/ml) have stronger antioxidant activity than the stems (IC50 = 1563.6 µg/ml). The extracts of the leaves and stems showed remarkable antioxidant activity in β-carotene/linoleic acid assay (96.2% and 95%, respectively). The total phenol and flavonoid contents of the species were determined using Folin-Ciocalteu and AlCl3 assays, respectively. The phenol and flavonoid contents of the leaves (301.0 µg/ml and 45.2 µg/ml, respectively) were observed more than the stems (172.3 µg/mg and 18.8 µg/mg, respectively).