Determination of Sesquiterpenic Acids with Sedative Properties in Extracts of Medicinal Lavender (Lavandula angustifolia Mill.)

Plant raw materials with a calming effect on the nervous system are increasingly used in modern phytotherapy. Lavender belongs to this group of plants, due to the content of essential oil with known therapeutic properties and other phytoconstituents that can be responsible for the sedative effect. Our studies confirmed the presence of sesquiterpenic acids characterized by sedative activity in lavender extracts. The contents of valerenic acid and acetoxyvalerenic acids in flowers and leafy stalks of two various Lavandula angustifolia cultivars—‘Blue River’ and ‘Ellagance Purple’—were determined. Analyses of methanolic extracts performed using the HPLC method showed that content of these sesquiterpenic acids varied with the cultivars and the morphological parts of the plant. The amount of acetoxyvalerenic acid was significantly higher than the amount of valerenic acid. In the ‘Blue River’ cultivar, higher levels of both compounds characterized by sedative properties were found. The content of valerenic acid in flowers ranged from 0.50 mg/100 g d.m. in the ‘Ellagance Purple’ cultivar to 1.75 mg/100 g d.m. in the ‘Blue River’ cultivar. In turn, leafy stalks contained 0.81 mg/100 g d.m. of valerenic acid in the ‘Ellagance Purple’ cultivar and 1.16 mg/100 g d.m. in the ‘Blue River’ cultivar. Interestingly, the ‘Blue River’ cultivar contained about 10 times more acetoxyvalerenic acid (65.80 mg/100 g d.m.) in flowers and four times more acetoxyvalerenic acid in leafy stalks (50.1 mg/100 g d.m.), in comparison with the ‘Ellagance Purple’ cultivar. The higher content of valerenic and acetoxyvalerenic acids in the flowers and leafy stalks of the ‘Blue River’ lavender cultivar can be important for its possible medical applications.