Composition and infraspecific variability of essential oil from Thymus camphoratus

The composition of the essential oils of seven populations of Thymus camphoratus from Portugal and their infraspecific variability were investigated by GC, GC-mass spectrometry and 13C NMR. The results obtained from GC analyses of the volatile oils from individual plants were submitted to Principal Component and Chemometric Cluster analyses. 1,8-Cineole, linalool, borneol, α-pinene, camphene, trans-sabinene hydrate, and terpinen- 4-ol were the main constituents. 13C NMR spectra of the essential oil, previously fractioned by column chromatography, let to the identification of two new oxygenated sesquiterpenes for the genus Thymus: intermedeol, which is reported for the first time in the Lamiaceae, and homalomenol-D. Multivariate analysis enabled four different groups of essential oils to be distinguished: (i) linalool, (ii) borneol, (iii) 1,8-cineole and (iv) 1.8-cineole/borneol.