The essential oils of the aerial parts of Hypericum perfoliatum L., were collected from two different localities Preveza (sample A) and Korinthos (sample B) from Greece. The fifty-two constituents representing 94.6% and 99.2% of the oils, respectively, a-pinene (48.5%), n-nonane (8.5%), a-pinene (34.2%) and b-pinene (9.2%) were found to be the major constituents. In this study antioxidant activity of the oils was evaluated using an in vitro method.

The genus Hypericum (Hypericaceae) is a large genus comprising 400 species widespread on temperate regions and tropical mountains. Forty-three species are found in the Hellenic peninsula (Greece) and on Aegean islands and coasts (Greece and Turkey), eight of which are endemics.

Plant material was collected during the flowering stage from Preveza, and from Korinthos. A voucher specimen has been deposited in the Laboratory of Pharmacognosy, University of Athens. 50.0g of the plant material was submitted for 3 hours to steam distillation with 300 ml H₂O, in a modified Clevenger apparatus comprising a water-cooled oil receiver to reduce hydrodistillation overheating artifacts. The essential oil was taken in pesticides analysis grade Et₂O and was subsequently dried. GC-MS analysis obtained from a Hewlett Packard 5973-6890 system operating in EI mode [equipped with a split/splitless injector (200°C); 1/10 split ratio), HP 5MS 30 x 0.25mm film thickness capillary column]. The initial temperature of the column was 60°C and grew to 280°C with a 3°C/min rate. The identification of the compounds was based on comparison of their retention times with those of authentic samples and/or by comparison of their mass spectra with those of the NBS/NIST and Wiley Libraries.

Antioxidant activity of the oils was evaluated using an in vitro method. The method was based on coupled oxidation of b-carotene and linoleic acid. This technique described by Silvia Taga et al., measures the bleaching of b-carotene resulting from the degradation products of linoleic acid.

Fifty-two constituents from the oils of H. perfoliatum, representing 94.6% and 99.2% of the oils were identified (Table 1). Among the monoterpene hydrocarbons, the two samples characterized by high contents of a-pinene (48.5%, 34.2%), respectively. The sesquiterpene hydrocarbons content ranged between 21.6% (sample A) and 37.6% (sample B) with d-cadinene presenting the highest value (8.1%). The oxygenated sesquiterpenes content ranged between 4.6% (sample A) and 6.5% (sample B). The oxygenated monoterpenes content was poor: 0.3% in sample A and 0% in sample B. H. perfoliatum from Preveza showed greater antioxidant potential than H. perfoliatum from Korinthos.

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2. Silvia Taga M., Miller E.E., Pratt D.E. (1984): Chia Seeds as a Source of Natural Lipid Antioxidants, JAOCS. 61, 928-931.

3. Adams R.P. (1995): Identification of Essential Oil Components by Gas Chromatography and Mass Spectometry, Allured Publ. Corp., Carol Sream, IL, USA.