Chemical composition and bioactivity of essential oils of Hypericum helianthemoides, Hypericum perforatum and Hypericum scabrum

Context: A number Hypericum species are well known for their therapeutic efficacy and use in traditional medicine. The various species of Hypericum have been traditionally used for the treatment of wounds, eczema, burns, trauma, rheumatism, neuralgia, gastroenteritis, ulcers, hysteria, bedwetting and depression. Objective: This study evaluated the in vitro antioxidant, antibacterial and phytochemical properties of essential oils of Hypericum helianthemoides (Spach) Boiss., Hypericum perforatum L. and Hypericum scabrum L. (Hypericaceae) collected from alpine region of Southwest Iran. Materials and methods: The essential oils obtained from dried flowering aerial parts of three Hypericum species were analyzed by gas chromatography and gas chromatography/mass spectrometry to determine chemical compositions. The antibacterial activity of essential oils within concentration ranges from 16 to 500 mg/mL was individually evaluated against Bacillus cereus, Listeria monocytogenes, Proteus vulgaris and Salmonella typhimurium. The 1,1-diphenyl-2-picrilhydrazyl (DPPH) radical scavenging activity of essential oils was determined using DPPH assay. Results: Essential oil yield of H. helianthemoides, H. scabrum and H. perforatum were 0.12, 0.20 and 0.21 mL/100 g dried material, respectively. The major constituents of the essential oils were alpha-pinene (12.52-49.96%), beta-pinene (6.34-9.70%), (E)-beta-ocimene (4.44-12.54%), beta-caryophyllene (1.19-5.67%), and germacrene-D (2.34-6.92%). The essential oils of three Hypericum species indicated moderate-to-good inhibitory activities against four bacteria, especially against L. monocytogenes. Discussion and conclusion: The essential oils of the three studied Hypericum species sourced in alpine region of West Iran were rich in monoterpene and sesquiterpenes hydrocarbons. Among the three tested species, the essential oil of H. scabrum showed the highest antibacterial and antioxidant activities.