## 1 Introduction  
The dynamic development of the chemical industry at the beginning of the 20 th century resulted in a retreat from traditional phytotherapy and natural methods of treatment. However, the development of advanced research and analytical methods also allowed for intensified studies on medicinal plant raw materials. The possibility of isolation of biologically active compounds from plants and their characterization contributed to the development of the pharmaceutical industry based on synthetic drugs, but also resulted in the intensive development of research on plant raw materials and plant-based medicines. The primary factor influencing the development of modern knowledge about various plant raw materials for medical applications is ability to determine their exact chemical composition, which allows for precise dosing, determining the mechanism of action, and confirming safety and effectiveness in randomized clinical trials. Nowadays, plant medicines are becoming more and more popular, and the therapeutic effectiveness of their constituents is recognized at the pharmacological, biochemical, and molecular levels. Compared to a synthetic drug as a single chemical compound, a herbal drug is a mixture of chemical substances with various directions and mechanisms of action. Their beneficial effects on health often result from synergism between compounds with different chemical structures. Due to the fact that stress and nervous tension are an increasingly common cause of lifestyle diseases, special attention is paid to herbal medicines that can affect the central nervous system through a multi-directional calming effect. Medicines can influence the activity of the central nervous system by inhibiting or stimulating it. Currently, antiaxiotic, antidepressants, and antineutrotics drugs enable effective treatment of various mental disorders [1]. In this group of drugs, the basic mode of action is related to their impact on emotional processes: they inhibit the symptoms of fear, excitement, aggressiveness, or anxiety. The majority of the drugs that affect the central nervous system are of synthetic origin; however, plant-origin substances are very popular among psychodysleptic drugs. Plant medicines are usually characterized by a weaker effect and require a longer period of use than synthetic ones. However, when dosed correctly, they are less likely to cause side effects, excessive sleepiness, or addiction. A large group of plant raw materials are known for their calming and sleep-inducing effect. Among them, valerian (_Valeriana officinalisis_), lemon balm (_Melissa officinalisis_), purple passionflower (_Passiflora incarata_), common hop (_Humulus lupulus_), and medicinal laverder (_Lavandula angustifolia_) are successfully used to inhibit mental hyperactivity and to facilitate falling asleep [1]. Medicinal laverder, also known as common laverder, is a plant found in many European countries, but also cultivated in North America [2]. The medicinal raw materials of this plant, which belongs to the _Lamiaceae_ family, are flowers (_Flos Lawandulae_), which should be collected before they bloom (in the bud stage). Lavernder flowers contain a minimum 1.4% of essential oil, as well as tannins, triterpenes, coumarins, phenolic acids, flavonoids, phytosterols, anthocyanins, and minerals [1,2]. Lavernder flowers, extracts, and essential oils are used traditionally for the reduction of stress and anxiety. In these applications, they are approved as plant medicines by the European Medicines Agency. Some studies performed on humans and animals show positive results in models of anxiety and stress, but there are still little available literature data related to the mechanisms of their action [1, 2, 3, 4, 5, 6, 7]. Medicinal laverder belongs to the plants with potential anticonvulsant, anti-depressant, anti-anxiety, hypnotic, and sedative properties [7, 8, 9, 10, 11]. Most scientific research on laverder has focused on the essential oil, which is credited with its main therapeutic activity.