Variability of Content and Composition ofMentha aquaticaL. (Lamiaceae) Essential Oil in Different Phenophases

The content and chemical composition of Mentha aquatica L. (Lamiaceae) essential oil during three phenophases (before flowering, flowering and after flowering) was compared. Quantities of the essential oils were determined according to the European Pharmacopoeia 4ed 12 and chemical profiles by GC-MS. The highest content of the essential oil was found before flowering stage (0.73%). The main constituent of the essential oil through all the three phenophases was menthofuran (19.0–24.5%), followed by 1,8-cineole (11.8–20.2%), E-caryophyllene (6.7–16.6%) and viridiflorol (7.6–9.0%). Although the composition of the essential oil in all the three investigated phenophases was generaly similar, some qualitative differences were observed (presence of α-guaiene, γ-murolene, valencene and germacrene B only before flowering, linalool and pulegone in the flowering stage, and α-thujene, geranyl acetate, α-bisabolol oxide and 1-octene-3-ol acetate after flowering). Furthermore, the differences in quantities of all compounds present in the essential oils were also recorded. However, the qualitative composition of main constituents of the essential oil in all the three investigated stages led to the suggestion that the menthofuran, as the major compound could be used as the stable chemosystematic marker in the Mentha aquatica L. taxonomy.