Chemical polymorphism of the essential oils from populations of Thymus caespiti...

• Author(s): Pereira, S. I. ; Santos, P. A. G. ; Barroso, J. G. ; Figueiredo, A. C. ; Pedro, L. G. ; Salgueiro, L. R. ; Deans, S. G. ; Scheffer, J. J. C.
• Date: 2000
• Persistent ID: http://hdl.handle.net/10316/5806
• Origin: Estudo Geral - Universidade de Coimbra
• Subject(s): Thymus caespirtitius; Lamiaceae; Essential oil; Chemical polymorphism; Enantiomers; Chemotypes
• Document Type: Article
• Language: English

Description

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 (69-91%). 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. http://www.sciencedirect.com/science/article/B6TH7-41K2349-C/1/cb06975bf5d34c6355b8edd36cafe7f0