Essential Oil Composition of Ten Species from Sect. Serpyllum of Genus Thymus Growing in Bulgaria

GC-MS/FID analysis of the essential oils of 10 Thymus species, belonging to Sect. Serpyllum, led to identification of 118 compounds accounting for 97.79–99.69% of the total oil. Thymus moesiacus, T. jankae, T. vandasii, T. longicaulis and T. sibthorpii were characterized by the presence of linalool (19.37–35.21%) as the major or dominant component, but differed significantly in the content of the other prominent components: linalyl acetate, geraniol, geranyl acetate, α-terpinyl acetate, myrcen-8-yl acetate, myrcen-8-ol, etc. α-Terpinyl acetate (66.79%), thymol (63.96%), carvacrol (42.65%) and germacrene D (42.15%) were the principal components of T. pulegioides, T. glabrescens, T. callieri and T. pannonicus, respectively. β-Myrcene (16.53%), cis-sabinene hydrate (13.58%), τ-cadinol (13.24%) and elemol (11.29%) determined the oil from T. thracicus as a mixed mono-/sesquiterpene chemotype. The obtained results revealed the existence of new chemotypes of T. moesiacus, T. thracicus, T. sibthorpii and T. longicaulis. The essential oil content of T. callieri and endemic T. vandasii is reported for the first time. The variations in the essential oils of different Thymus species from Sect. Serpyllum were examined by principal component analysis (PCA) and cluster analysis (CA).