Southern French thyme oils: chromatographic study of chemotypes

Oils obtained from seven chemotypes (thymol, linalool, geraniol, borneol, (E)-sabinene hydratelterpinene-4-ol, p-cymene and carvacrol) of Thymus vulgaris (thyme) that exist in the South of France were analysed by gas chromatography/mass spectrometry (GC/MS) and characterised. Wild thyme growing in three departments (Bouches du Rhone, Var and Vaucluse) of Provence and in a fourth neighbouring department (Gard) was also studied. This is often the result of a mixture of three chemotypes: thymol, carvacrol and p-cymene. Linalool and (E)-sabinene hydrate/terpinene-4-ol were observed as minor chemotypes. GC/MS was also used to monitor seasonal variations in the composition of the oil obtained from thyme harvested at the same location (Gemenos, near Marseille, Bouches du Rhone) during the plant vegetative and life cycles (19 samples). Four components were determined: the phenols thymol and carvacrol and the monoterpene hydrocarbon precursors p-cymene and gamma-terpinene. Results showed maximum oil (34.1 mL kg(-1) dry matter) and phenolic terpenoid (95.4 mmol kg(-1) dry matter) contents occurring in May, the period of flowering and harvesting. In contrast, in December the oil displayed a higher level of phenolic precursors (p-cyrnene and gamma-terpinene, 72.8 mmol kg(-1) dry matter) than phenolic terpenoids. Depending on the harvesting date, the oils isolated from southern French thyme (T. vulgaris) could have different potential biological activities. (c) 2005 Society of Chemical Industry.