## 1 Introduction  
The synthesis of antioxidants, a natural source of plant metabolism, serves as a means of defense against biotic and abiotic factors in the environment. Environmental stressors can increase levels of reactive oxygen species (ROS), leading to an imbalance in their production and scavenging, which causes oxidative stress. Reactive oxygen species are thought to be responsible for many cell disorders through their chemical attacks on biostructures. These species are constantly generated as a result of human metabolism due to oxidation. Furthermore, ROS can be generated because of various external factors. As a defense mechanism, plants activate enzymatic and non-enzymatic systems in their metabolism to prevent damage to proteins, membranes, and DNA, protecting them from oxidative stress and related diseases [1; 2; 3; 4]. Many plant species, owing to their high amounts of essential oils, are of medicinal and economic importance. The plants show, e.g., anti-inflammatory, antispasmodic, antioxidant, antibacterial, antifungal, antidiarrheal, and antiviral activities. Most of the green plants, vegetables, and fruits are known as the main sources of natural antioxidants. Consuming these antioxidants in the human diet is a sensible method to minimize, among others, brain dysfunction, cardiovascular diseases, cataracts, or risk of cancer [5; 6; 7]. One of the groups of plants with confirmed pharmacological effects (including antioxidant effects) is _Betula_ (birches), belonging to the _Betulaceae_ family. There are over 140 species of trees within the genus _Betula_ that are known in the world. The genus _Betula_ is widespread in northern temperate and Arctic regions, from Afghanistan to the Himalayas, Japan, Kazakhstan, Korea, China, Kyrgyzstan, Russia, Nepal, Mongolia, Sikkim, Europe, and into both Americas. Various pharmacological properties of the _Betula_ species have found application in ethnomedicine. Currently, there are many pharmacological research results that confirm a wide range of health-promoting properties. Researchers have also shown that these plants can heal skin and digestive system diseases (hepato- and gastoprotective effect) [8; 9; 10]. In Europe, three naturally occurring species are particularly important, including commercial ones: white birch (_Betula alba_), silver birch (_Betula pendula_ [PERSON]), and _B. pubescens_. Extracts and biologically active ingredients isolated from these species are used in cosmetics, dietary supplements, and biocides. Birch sap, extracted from the trunk, is used as an aid in the treatment of urinary tract diseases and dermatological diseases, as well as arthritis and rheumat [11]. The antibacterial potential of extracts and essential oils from various _Betula_ species, including _B. pendula_, is also often highlighted [12; 13]. [PERSON] et al. [12] analyzed the antibacterial potential of methanol extracts from various raw materials of _B. pendula_--external and internal flowers, bark, buds, and leaves. In the case of leaf decoctions and leaf methanolic extracts, the researchers observed the largest zones of growth inhibition against _S. aureus_. In the case of leaf and internal bark methanolic extracts, they observed a significant zone of growth inhibition for _P. aeruginosa_. Leaf extracts showed no activity against _B. subtilis_, while _E. coli_ was not sensitive to any of the extracts tested (no visible inhibition zone) [12]. In addition to assessing the surface disinfection and hand disinfection of silver birch leaf preparation, the aim of our study was also to assess the antioxidant activity of an ethanolic preparation obtained from this raw material. _Betula_ plants are known for their antioxidant potential. Researchers suggest that the polyphenic compounds in the leaves of _B. pendula_ are responsible for this activity. This raw material is a valuable source of antioxidants such as myricetin, catechin, p-coumaric acid, kaempferrol, and quercetin [14]. [PERSON] et al.