Variations of essential oil characteristics of Clinopodium pulegium (Lamiaceae) depending on phenological stage

The variability of essential oil characteristics in different phenological stages of Clinopodium pulegium from its natural habitat (Svrljiški Timok gorge, Serbia) and from cultivated plants (Niš, Serbia) was determined. The essential oils were obtained from aerial parts of the plants by hydrodistillation and analyzed by GC-MS. These are the first data on the essential oil characteristics of plants of the population from the Svrljiški Timok gorge. Samples originating from both natural and cultivated populations were characterized by high amounts of essential oils in all stages of development (0.8% 1.4%). Twenty-one compounds were identified, representing 95.3-99.6% of the total oils. Differences in the essential oil composition were more quantitative than qualitative. The quality of the essential oil was stable and did not vary with differences in environmental conditions. Dominance of the main components was modified by phenological stage. Pulegone was dominant in the vegetative (76.1% wild population, 62.7% cultivated population) and the flowering (49.5%, 64.6%) stages, while menthone (48.5%, 65.3%) displaced pulegone (34.7%, 18.4%) at the fruiting stage. Cultivated plants in the vegetative and flowering stages can be considered a significant source of pulegone, and in the fruiting stage a significant source of menthone. Careful selection of the developmental stage of the plant is a potential tool which could be employed to obtain the preferred chemical composition of C. pulegium for commercial use.