Chemical and Biological Characterization of Essential Oils Extracted from Thymus Vulgaris

The renewed interest in medicinal and aromatic plants and the increase in their market demand have favoured rural development programs for their cultivation, also as a measure to counteract the profound crisis affecting some agricultural sectors. Sage (Salvia officinalis) is a plant of the Lamiaceae family, whose leaves contain some different active ingredients, which confer sage-based preparations any properties. In particular, sage essential oil (EO) is known for its antiseptic and balsamic properties. Methods: The chemical investigation of a leaf EO, obtained from sage plants experimentally cultivated in the Benevento area (Campania, Italy), was achieved using analytical techniques as Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography coupled to Mass Spectrometry (GC-MS) and flame ionization detector (FID). Furthermore, in order to strengthen potential uses of products based on locally cultivated sage, different assays were performed to evaluate its antioxidant effects. Results: In the FT-IR spectrum of sage essential oil the absorption bands at 3460 cm-1 showed the presence of O-H stretch, H- bonded for alcohol and phenol, and at 2956, 2927 and 2872 cm-1, which were for alkane asymmetrical and symmetrical C-H stretches. The strong sharp band at 1741 cm-1 was attributable to the C=O stretching in cyclic ketones having ring strain, as camphor or thujone. CH2 bending vibrations were detectable at 1458 cm-1. The C=C stretching mode of a vinylidene double bond was detectable at 1645 cm-1 (e.g. β-myrcene and camphene). Twenty-nine compounds were identified by means of GC-MS and GC-FID analyses. According to literature data on sage essential oils, oxygen containing monoterpenes were the most abundant compounds. α-Thujone, 1,8-cineole and camphor were the main components, representing the 23.2%, 20.9% and 20.4%, respectively. The β-thujone content was equal to 6.4%. The bicyclic sesquiterpene β-caryophyllene amounted for the 5.83%. The EO radical scavenging features were measured by applying spectrophotometric DPPH and ABTS methods. ABTS cation radical was more sensitive than DPPH radical to the tested essential oil. Our results are not in line with those reported by Bozin and co-workers, who showed that sage essential oil markedly reduced DPPH radical. Conclusions: The data obtained in this work may encourage the cultivation of this plant, in order to obtain sage based products healthy for consumers.