Chemical composition and antibacterial activity of essential oils of Tripleurospermum disciforme in three developmental stages

Context: Tripleurospermum disciforme (C.A. Mey) Schultz Bip. (Asteraceae) is a widespread biennial species which also has traditional medicinal uses. According to the few recent studies, essential oils of this species exhibit anti-inflammatory, antispasmodic, antiseptic, antifungal, antiulcer, and antioxidant activity. Objective: The chemical compositions of the hydrodistilled oils of T. disciforme of Iranian origin are studied in the stages of prior to flowering, flowering, and post flowering, for the first time. Also, we investigated the antibacterial activities of the oils. Materials and methods: The essential oils of air-dried T. disciforme were obtained by hydrodistillation in three different developmental stages and analyzed by gas chromatography-mass spectrometry (GC-MS). The antimicrobial activity of the isolated essential oil, in the three stages, was also investigated against four Gram-positive and four Gram-negative bacteria. Results: Twenty-one components were identified in the essential oils of T. disciforme, and the highest amount of oil was extracted at the flowering stage. The main component of the species in the flowering stage was beta-farnesene (22.46%) and the other major components were beta-sesquiphellandrene (17.85%), p-methoxy-beta- cyclopropylstyrene (16.64%), heptadecane (10.6%), p-methoxy-humulene oxide (6.88%) and benzene acetaldehyde (9.3%). The MIC of essential oil was evaluated from 4 mu L ml(-1) against Staphylococcus subtilis and Bacillus cereus to 22 mu L ml(-1) against Citrobacter amalonaticus. Discussion and conclusion: This study demonstrates the occurrence of beta-farnesene/beta-sesquiphellandrene chemotype of T. disciforme in western regions of Iran that are different from previous reports. The findings also showed that the essential oils T. disciforme have excellent antibacterial activities and thus have great potentiality to be used as a resource for natural health products.