Essential Oil Composition, Antioxidant Activity and Total Phenolic Content of Some Lamiaceae Taxa Growing in Northwest of Iran

Lamiaceae family is one of the main sources of aromatic and medicinal plants. In the present study essential oil constituents, free radical-scavenging activity and total phenolic content of the aerial parts of four Lamiaceae taxa, Ziziphora tenuior (ZT), Scutellaria orientalis subsp. virens (SO), Eremostachys laciniata subsp. iberica (EL) and Phlomis herba-venti subsp. pungens (PH), collected from "Mishu-Dagh" region (Northwest of Iran) were investigated. GC and GC-MS were applied for the analysis of plants oils. Free radical-scavenging activity and total phenolic content of the plants hydroalcoholic extracts and their polar and non-polar fractions were also evaluated using DPPH and Folin-Ciocalteu methods, respectively. A total of 58 compounds were identified in essential oils, among them 1,8-cineol (19.6%), germacrene D (16.5%), linalool (10.2%) and germacrene D (11.7%) were characterized as main compounds in ZT, SO, EL and PH oils, respectively. In DPPH assay, polar fractions of EL and ZT exhibited considerable free radical-scavenging activity (IC50; 11.0 ± 2.3 and 12.7 ± 2.7 μg ml-1, respectively) in comparison with BHT (IC50; 10.8 ± 2.1 μg ml-1). The former fractions were also found to contain the highest total phenolic content (231.9 ± 9.3 and 214.1 ± 11.3 mg EGA/g, respectively). The present study introduces these four taxa as the plants with terpene rich oils and suggests them as potential sources of free radical-scavenging compounds.