Traditional, Therapeutic Uses and Phytochemistry of Terrestrial European Orchids and Implications for Conservation

The Orchidaceae family accounts for about 28,000 species, and most of them are mentioned in the folk medicine of nations around the world. The use of terrestrial orchids in European and Mediterranean regions has been reported since ancient times, but little information is available on their medicinal properties, as well as on their phytochemicals and biological activities. However, plant collection for human use is still listed as one of the main threats for terrestrial orchids, alongside other menacing factors such as wrong habitat management and disturbance to symbionts, such as pollinators and mycorrhizal fungi. Therefore, the primary aim of this review was to resume and discuss available information regarding the past and current popular uses of European orchids. We then grouped phytochemical data to evaluate the presence of bioactive compounds of pharmacological relevance, and we discussed whether these could support the therapeutic employment of the different organs. Finally, we briefly debated the sustainability of orchid utilizations, considering the different threatening factors and conservation actions including plant propagation methods.

Chemical Composition and Antioxidant Activity of Essential Oil from the Aerial Parts of Teucrium luteum (Mill.) Degen subsp. flavovirens (Batt.) Greuter & Burdet Growing Wild in Tunisia

Essential oils (EOs), the odorous and volatile products of a plant’s secondary metabolism, have wide applications in folk medicine, in food flavoring and preservation, and in fragrance industries. The aim of this study was to analyze the chemical composition of the EO from the aerial parts (including the inflorescences) of wild Teucrium luteum subsp. flavovirens from Tunisia. The EO obtained by the hydrodistillation of air-dried plant material in a Clevenger-type apparatus was analyzed using gas chromatography coupled with mass spectrometry (GC-MS). Fifty-three components representing 83.9% of the total constituents were identified. The EO of T. luteum subsp. flavovirens is characterized by the presence of β-elemol (7.2%), (+)-α-pinene (6%), β-eudesmol (5.5%), guaiol (4.2%), α-bisabolol (4.2%), and β-caryophyllene (4.1%) as principal chemical components. In vitro (DPPH and β-carotene bleaching assays), it showed significantly higher radical scavenging and antioxidant properties than the reference compound, BHT. To the best of our knowledge, this is the first report describing the composition and antioxidant properties of the EO from Tunisian T. luteum subsp. flavovirens. Our preliminary data will help to valorize this potentially useful plant species from Tunisia and represent a starting point for further studies on its volatile fraction.

Characterization and Antioxidant Activity of Essential Oil of Four Sympatric Orchid Species

The volatile fractions from fresh inflorescences of naturally growing orchids Anacamptis coriophora (L.) R. M. Bateman, Pridgeon & M. W. Chase subsp. fragrans (Pollini), Anacamptis pyramidalis (L.) R. Ophrys holosericea (Burm.) Greuter and Serapias vomeracea (Burm. f.) B. were isolated by steam distillation and analyzed by GC/FID and GC/MS. Saturated hydrocarbons were quantified as the major constituents of the volatile fraction (47.87–81.57% of the total essential oil), of which long-chain monounsaturated hydrocarbons accounted from 9.20% to 32.04% of the total essential oil. Double bond position in linear alkenes was highlighted by dimethyl disulfide derivatization and MS fragmentation. Aldehydes (from 3.45 to 18.18% of the total essential oil), alcohols (from 0.19% to 13.48%), terpenes (from 0.98 to 2.50%) and acids (0.30 to 2.57%) were also detected. These volatiles compounds may represent a particular feature of these plant species, playing a critical role in the interaction with pollinators. DPPH assay evaluating the antioxidant activity of the essential oils was carried out, showing a dose-dependent antioxidant activity.