title: Chemical polymorphism of the essential oils from populations of Thymus caespititius grown on the island S. Jorge (Azores).
abstract: The compositions of the essential oils obtained from ten populations of Thymus caespititius grown on S. Jorge (Azores) were studied by GC and GC-MS. All the oils analysed were dominated by their monoterpene fraction (69-9%). The sesquiterpene fraction was rather small (4-17%) and consisted mainly of oxygen-containing compounds (3-13%). Enantiomeric ratio of sabinene and alpha-terpineol was investigated in the oils from some populations. (+)-Sabinene was detected with high enatiomeric purity (96 99%). Although ( +)-alpha terpineol was the predominant enantiomer, its purity varied considerably (66-97%). Cluster analysis of all identified components grouped the oils into four main clusters that corresponded with their major components: alpha-terpineol (43-68%), carvacrol (32-52%), thymol (44-58%) and sabinene (41%). The essential oil from Th. caespititius showed a clear chemical polymorphism, that was particularly evident among four populations growing along a 200 m distance at Pico Verde.
authors.affiliation: Centro de Biotecnologia Vegetal, Departamento de Biologia Vegetal, Faculdade de Ciências de Lisboa, Lisbon, Portugal.
authors.forename: S I
authors.initials: SI
authors.lastname: Pereira
authors.forename: P A
authors.initials: PA
authors.lastname: Santos
authors.forename: J G
authors.initials: JG
authors.lastname: Barroso
authors.forename: A C
authors.initials: AC
authors.lastname: Figueiredo
authors.forename: L G
authors.initials: LG
authors.lastname: Pedro
authors.forename: L R
authors.initials: LR
authors.lastname: Salgueiro
authors.forename: S G
authors.initials: SG
authors.lastname: Deans
authors.forename: J J
authors.initials: JJ
authors.lastname: Scheffer
mesh_terms: D008401:Gas Chromatography-Mass Spectrometry; D019686:Lamiaceae / Q000737:chemistry*; D019684:Magnoliopsida / Q000737:chemistry; D009426:Netherlands; D009822:Oils, Volatile / Q000737:chemistry* / Q000145:classification; D010936:Plant Extracts / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D009822:Oils, Volatile; D010936:Plant Extracts