Chemical composition and antioxidant activity of the essential oil and various extracts of Inula graveolens (L.) Desf.

Abstract

In this study, chemical composition and in vitro antioxidant activity potential of the essential oil and various extracts of Inula graveolens (L.) Desf. were evaluated. While identifying the phytochemical composition of the essential oil and extract, GC-MS analyses were used. Chromatographic analysis of the essential oil resulted in identifying twenty compounds representing 99.5% of the total oil. Main constituents of the oil were determined as bornyl acetate (68.5%), borneol (7.7%), camphene (4.6%), epi-alpha-cadinol (4.0%) and eicosane (3.2%), respectively. Antioxidant activity was determined using four complementary test systems named beta-carotene/linoleic acid, DPPH free radical scavenging, reducing power, and chelating effect. A strong correlation between the antioxidant activity and phenolic acid contents of the samples was determined. The methanol extract was the most active one in all tested systems. The weakest activity was exhibited by chloroform extract. While methanol extract showed 88.34%, 91.38, and 63.43 activities in beta-carotene bleaching, DPPH radical scavenging, and chelating effect tests, respectively, the absorbance value in reducing power assay was measured as 0.273 nm.