Changes of the chemical composition of the essential oil of Portuguese thymus mastichina in the course of two vegetation cycles
2002
Miguel, M.G. | Duarte, F. | Venâncio, F. | Tavares, R. | Guerrero, C. | Martins, H. | Carrasco, J.
In the present work, the chemical composition of the essential oils obtained from Thymus mastichina (L.) L. subsp. mastichina was evaluated over a two year period. The oils were analysed by GC and GC/MS following 3 hours distillation of plant material, using Likens-Nickerson-type apparatus. The major component in the essential oils was 1,8-cineole, an oxygenated monoterpene, whose concentrations ranged from 42.2 % to 50.4 %. Camphor was another oxygenated monoterpene being present in relative high amount (7.4 %-11.5 %). α-Pinene, camphene and β-pinene were the most important monoterpene hydrocarbons in the essential oils. The ratio of camphene changed on a large scale in the course of two vegetation cycles. With minimum and maximum concentrations ranging from 3.1 % to 6.3 %. β-Caryophyllene, γ-Cadinene and elemol were the most representative sesquiterpenes accumulating in a small amount, only (less than 2.5 %). The effect of the collection time, however, proved to be a factor of restricted importance.
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