Phytochemical Variability of Essential Oils of Two Balkan Endemic Species: Velen. and Wierzb. Ex Heuff. (Lamiaceae)

and (Lamiaceae) are Balkan endemic plant species, and the composition of their essential oil (EO) is highly variable. The aim of the present study was to establish: (1) the EO variability in two populations of (the intrapopulation), and (2) the EO variation in between nine populations (interpopulation) from Bulgaria and two from Serbia. The EOs of two species were obtained from aboveground plant parts by hydrodistillation and were analyzed by GC/MS/FID. Overall, the EO yield on the intrapopulation level of varied from 0.54% to 2.15%, while the EO of varied from 0.04% to 0.43% (interpopulation). The EO of was found to contain thymol and carvacrol as the main constituents, with other major constituents being -cymene and -terpinene. samples in both studied populations formed six chemical groups. The major constituents (-cymene, terpinen-4-ol, bornyl acetate, -muurolene, -borneol, --ocimene, --ocimene, carvacrol, -pinene, thymoquinone, geranial, geranyl acetate, spathulenol, and caryophyllene oxide) of EO were considered for grouping the populations into ten chemotypes. The present study is the first report on the interpopulation diversity of EOs in Bulgaria. It demonstrated variability of the EOs between and within the populations of from Bulgaria. This study identified promising genetic material that could be further propagated and developed into cultivars for commercial production of and , thereby reducing the impact of collection on wild populations.