Chemical composition of essential oils of medicinal and aromatic plants – Pirot District

Abstract

The composition of essential oils of 10 species of aromatic and medicinal plants from Pirot District was examined. Protected, rare, or poorly researched species were chosen for investigation. They belong to the families Asteraceae (Achillea clypeolata, A. coarctata, A. crithmifolia, and A. millefolium), Apiaceae (Seseli libanotis and S. pallasii), and Lamiaceae (Satureja montana, Sideritis montana, Teucrium chamaedrys and T. montanum). Most of them are protected by the Law of the Republic of Serbia. All selected species flower from mid-June to early July. In that period, plant sampling was carried out on Mts. Stara Planina, Vlaška, and Vidlič and in the vicinity of Dimitrovgrad, at 500-1300 m a.s.l., to determine yield and chemical composition of the oil. Samples were dried immediately after collection at the registered agricultural holding „Cvetković“ in Pirot, and then transported to the laboratory of the Faculty of Chemistry in Belgrade. The highest essential oil yield was found in the following species: S. libanotis (1.40%), A. crithmifolia (0.94%), Satureja montana (0.30%) and A. millefolium (0.25%), while it was weak in other species (0.02-0.07%). The chemical composition of the oil was determined by gas chromatography-mass spectrometry (GC-MS). In the case of the first 3 examined plants from the family Asteraceae, the following compounds dominated: 1,8 cineole and camphor (with significant differences in terpene profiles), and in A. millefolium, b-pinene and trans-caryophyllene dominated. In the family Apiaceae, a high proportion of oxygenated monoterpenes (OM) and a pronounced dominance of b-elemene were found in Seseli libanotis, while in S. pallasii, a high proportion of monoterpene hydrocarbons (MH) and OM, especially limonene, was found. However, this similarity was not observed in the dominant components: geraniol, germacrene D, b-caryophyllene and the group of terpenes. In the family Lamiaceae, the share of OM was high in Satureja montana and Sideritis montana, but there was also the most MH and oxygenated sesquiterpenes (OS) (respectively, in comparisons of all 4 species). Teucrium chamaedrys and T. montanum stand out with a high proportion of sesquiterpene hydrocarbons (SH), and T. montanum also has OS. However, the dominant components in all 4 species differ in the content of geraniol, germacrene D, b-caryophyllene, or group of terpenes (Satureja montana, Sideritis montana, Teucrium chamaedrys and T. montanum, resp.).