Essential oil composition of Sideritis hirsuta L. from Guadalajara Province, Spain

The essential oil from the aerial parts of Sideritis hirsuta L. gathered in Guadalajara Province, Spain, has been extracted by steam distillation and analysed by gas chromatography (GC) and gas chromatography coupled to mass spectrometry (GC–MS). A total of 73 compounds have been identified, monoterpene compounds being the most important. The principal constituents have been identified as β‐phellandrene (23.8%), α‐phellandrene (9.2%), α‐pinene (8.2%) and (Z)‐β‐guaiene (8.1%). Although the chemical composition of the essential oil of this species from other provinces is similar, 44 of the 73 identified compounds have not been previously reported in this species. It is the first time that the sesquiterpene (Z)‐β‐guaiene (8.1%) has been detected and mentioned as a major constituent in this species, therefore it could be considered to describe a new chemotype for Sideritis hirsuta L.