Essential Oil and Glycosidically Bound Volatiles of Lemonscented Thyme, Thymus x Citriodorus (Pers.) Schreb.

The essential oil from fresh aerial parts of Thymus x citriodorus, probably a hybrid between T. vulgaris L. and T. pulegioides L., was analysed by GC and GC-MS. Geraniol was found to be the main compound (more than 60%) which kept its high level from July to October. Geranyl acetate (1.0%), geranyl butyrate (0.8%), nerol (2.8%), and citronellol (0.3%) were also detected. The lemon-scented compounds geranial and neral amounted to 8.2% and 5.5% respectively. The content of thymol (0.5%) was remarkable. In fresh plant material the glycosidically bound volatiles amounted to 0.003-0.013%. After enzymatic hydrolysis, geraniol was found to be the main aglycone (45%), bound to glucose in the glycosidic fraction. Other important aglycones were a farnesol isomer (7.3%), nerol (3.5%), alpha-cadinol (0.4%) and citronellol (0.4%). Thymol only amounted to 0.5% in the aglycone fraction. Other aglycones, such as the aliphatic alcohols present, and benzyl alcohol, 2-phenylethanol, eugenol, and the terpenes terpinen-4-ol and linalol, can more or less be considered as ubiquitous in aglycone fractions. The correspondingly high level of geraniol in the essential oil and in the aglycone fraction shows a correlation between the free and bound volatiles in the plant.