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Changes of the chemical composition of the essential oil of Portuguese thymus mastichina in the course of two vegetation cycles

Miguel, M.G., Duarte, F., Venâncio, F., Tavares, R., Guerrero, C., Martins, H., Carrasco, J.
Acta horticulturae 2002 no.576
chemical composition, Thymus mastichina, beta-pinene, cineole, essential oils, alpha-pinene, camphene, beta-caryophyllene, camphor, oils, distillation, vegetation
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.