## 3 Results and Discussion
### Antioxidant Activity  
Free radicals are groups of atoms or molecules that have one or more unpaired electron, which makes them chemically unstable and highly reactive. The presence of free radicals in the body is associated with the development of many diseases and also accelerates the aging of tissues. An important role in preventing the effects of free radical activity is played by antioxidants, which are supplied to the human body in food. The most important source of antioxidants in the diet are fruits, vegetables, and herbs. However, the preservation of these products is associated with significant losses of valuable antioxidants. Drying is the most popular method of preserving herbaceous plants; therefore, the search for the method and the parameters of drying leading to the preservation of antioxidant capacity is very important [46; 48; 49]. An Antioxidant activity is caused by numerous agents, such as vitamins (A, C, and E), minerals (zinc, selenium, copper, manganese, and iron), carotenoids (\(\alpha\)- and \(\beta\)-carotene, zeaxanthin, lutein, lycopene, and \(\beta\)-cryptoxanthin), and polyphenols (flavonoids, phenolic acids, lignans, and stilbenes). Most of them are sensitive to high temperatures. There are many methods for testing antiradical activity; in this work antioxidant activity was analyzed based on the scavenging of two synthetic radicals, DPPH* and ABTS\({}^{\circ+}\). The results were expressed as EC\({}_{50}\), i.e., the concentration of the leaf extract (fresh and dried) required to inhibit half of the initial amount of the radical. This means that lower EC\({}_{50}\) values indicate higher antiradical activity [17; 41; 46; 48]. The drying of Moldavian dragonhead leaves, regardless of the parameters used, caused a decrease in the radical scavenging of the dried material, compared to the raw material (Figure 4). The EC\({}_{50}\) ABTS\({}^{\circ+}\) of the extracts from the fresh leaves was 11.20 mg chlorogenic acid/g d.m., while in the convection-dried leaves it was 19.61-24.5 mg chlorogenic acid/g d.m. and in the microwave-dried leaves it was 16.5-19.9 mg chlorogenic acid/g d.m. The EC\({}_{50}\) DPPH* in the fresh leaves was 14.96 mg TE/g d.m., while in the convection-dried leaves it was 23.23-27.41 and in the microwave-convection-dried leaves it was 18.12-25.14 mg TE/g d.m. A decrease in radical scavenging activity during the drying of herbaceous plants was found in many works [2; 14; 46; 47; 48]. Similar results were obtained by [PERSON] et al. [2]. The researchers analyzed the antioxidant activity of fresh and convection-, vacuum-, and freeze-dried leaves of Moldavian dragonhead. The highest radical scavenging activity was characterized by freeze drying, the lowest by convection drying, while the increase in the temperature of the drying agent decreased the antioxidant activity measured by ABTS\({}^{\circ+}\)[2]. In this study, a decrease in antioxidant activity was also observed with an increase in the temperature of the drying agent. The leaves dried at 40 \({}^{\circ}\)C were characterized by an antiradical activity of 19.6 mg chlorogenic acid/g d.m. EC\({}_{50}\) ABTS\({}^{\circ+}\) and 14.96 mg TE/g d.m EC\({}_{50}\) DPPH*, while those dried at 70 \({}^{\circ}\)C were characterized by an antiradical activity of 23.99 mg chlorogenic acid/g d.m. and 27.41 mg TE/g d.m (Figure 5). The correlation coefficient between TPC and DPPH* was \(-\)0.89, and between TPC and ABTS\({}^{\circ+}\) it was \(-\)0.88. This means that the antioxidant activity of Moldavian dragonhead leaves is created mainly by phenolic compounds. Despite the fact that the dried leaves of Moldavian Dragonhead are a well-known and valued element of folk medicine, the scientific literature available so far lacks extensive information on the selection of appropriate drying methods. The studies published so far by [PERSON] et al. [2] concerned several selected conventional drying methods.