Chemical composition, antioxidant and antimicrobial activity of essential oil and extracts of Tragopogon graminifolius, a medicinal herb from Iran.

Tragopogon graminifolius DC., family Compositae, is widely consumed as a green vegetable in the west of Iran and for the treatment of gastrointestinal and hepatic ailments. In this study, the chemical composition of the essential oil from T. graminifolius aerial parts was evaluated by gas chromatography and gas chromatography mass spectrometry. Moreover, antioxidant and antimicrobial activity of the essential oil and various extracts of T. graminifolius were determined. Fifty-eight compounds representing 87.2% of the essential oil were identified. The main components were n-hexadecanoic acid (22.0%), beta-caryophyllene (7.5%), heneicosane (6.6%), and nonanal (5.2%). The essential oil demonstrated the highest DPPH radical scavenging activity (56.6 +/- 8.8 ug/mL) and the 80% ethanolic extract the highest ferric reducing antioxidant activity (908.2 +/- 79.5 mmol Fe2+ ion/g extract). The total phenolic content of the 80% ethanolic extract from the aerial parts was the highest (560.7 +/- 18.8 mg/g gallic acid equivalent). In the antimicrobial test, Shigella dysenteriae was the most vulnerable microorganism, followed by Proteus vulgaris, and the essential oil exhibited the highest antibacterial activity among the samples. The results indicated that the essential oil and extracts of T. graminifolius could be consumed as a natural herbal preservative or complementary supplement in the food and pharmaceutical industries.