Volatile oil Yield and Composition of Sideritis syriaca subsp. nusairiensis (Post) Hub.-Mor. Distributed in the Flora of Türkiye

The genus Sideritis, belonging to the family Lamiaceae, comprises a group of plants commonly known as 'ironwort' and 'mountain tea' worldwide, and locally as 'dağ çayı' and 'yayla çayı' in Türkiye. The Sideritis genus is represented by 46 species and 53 taxa in total, 39 of which are endemic to Türkiye. In this study, the volatile oil content and composition of Sideritis syriaca subsp. nusairiensis (Post) Hub.-Mor., which is distributed in the southern and southeastern regions of Türkiye, were identified. This species is mainly gathered from the nature for use in the treatment of influenza and colds, also as tonics, carminatives, diuretics, digestives, anti-inflammatory agents, and antispasmodics in the folk medicine. The volatile oil of the dry herbs obtained by hydrodistillation with neo-Clevenger apparatus was analyzed by gas chromatography and gas chromatography/mass spectrometry (GC-FID/MS). The oil yield was 0.05% (v/w). A total of twenty-two compounds, accounting for over 99% of the oil, were identified. The volatile oil was found to be rich in monoterpene hydrocarbons, primarily consisting of α-pinene (23.62%), β-pinene (30.73%), and dl-limonene (7.69%), as well as sesquiterpenes, mainly (E)-β-farnesene (9.00%) and δ-cadinene (3.06%).