## 4 Discussion  
Several studies support the pharmacological effects of extracts from the _Betula pendula_ plant, including its antibacterial and antioxidant potential [11; 47; 48]. Most published studies focus on extracts from the bark of this plant. The novelty of this study is the GC-MS analysis of the composition of the leaf preparation (Table 4) and the quantitative analysis of selected phenolic acids (gallic acid, 3,4-dihydroxybenzoic acid, 2,5-dihydroxybenzoic acid, chlorogenic acid, and 3-hydroxybenzoic acid) contained in the ethanolic leaf preparation (Table S1, Figure 1). Analyses of the composition of the _Betula pendula_ leaf preparation were not found in the literature, but analyses of oil and extracts from the bark of this plant are avail \begin{table}
\begin{tabular}{c c c} \hline \multicolumn{3}{c}{**Phase II, Stage II**} \\ \hline
**Birch** & **Contact Time** & _Staphylococcus aureus_ & _Pseudomonas aeruginosa_ \\
**Preparation/Ethanol** & & **ATCC 6538** & **ATCC 15442** \\ \hline \multirow{6}{*}{C\({}_{\rm P}\) = 70 g/100 mL} & \(10^{-0}\): 0; 0 & \(10^{-0}\): 0; 0 \\  & \(10^{-1}\): 0; 0 & \(10^{-1}\): 0; 0 \\  & \(10^{-2}\): 0; 0 & \(10^{-2}\): 0; 0 \\  & Nid: 0:10 & Nid: -010 \\  & Nvs: 0 & Nts: 0 \\  & R: \(>\)7.04 & R: \(>\)7.03 \\ \hline \multirow{6}{*}{C\({}_{\rm P}\) = 80 g/100 mL} & \(10^{-0}\): 0; 0 & \(10^{-0}\): 0; 0 \\  & \(10^{-1}\): 0; 0 & \(10^{-1}\): 0; 0 \\  & \(10^{-2}\): 0; 0 & \(10^{-2}\): 0; 0 \\  & Nid: 0:10 & Nid: -010 \\  & Nvs: 0 & R: \(>\)7.04 \\ \hline \multirow{6}{*}{C\({}_{\rm P}\) = 90 g/100 mL} & \(10^{-0}\): 0; 0 & \(10^{-0}\): 0; 0 \\  & \(10^{-1}\): 0; 0 & \(10^{-1}\): 0; 0 \\  & \(10^{-2}\): 0; 0 & \(10^{-2}\): 0; 0 \\  & Ntd: \(<\)0.10 & Nid: \(<\)0.10 \\  & R: \(>\)7.04 & R: \(>\)7.03 \\ \hline \multirow{6}{*}{C\({}_{\rm E}\) = 80 g/100 mL} & \(10^{-0}\): 129; 132 & \(10^{-0}\): 107; 135 \\  & \(10^{-1}\): 68; 83 & \(10^{-1}\): 87; 95 \\  & \(10^{-2}\): 29; 22 & \(10^{-2}\): 8; 9 \\  & Nsc: 312 & Nsc: 3.08 \\  & Nts: 20 & Nts: 100 \\  & R: 40.2 & R: 4.05 \\ \hline \multirow{6}{*}{C\({}_{\rm E}\) = 90 g/100 mL} & \(10^{-0}\): 33; 37 & \(10^{-0}\): 28; 34 \\  & \(10^{-1}\): 1; 7 & \(10^{-1}\): 1; 1 \\ \cline{1-1}  & \(10^{-2}\): 0; 0 & \(10^{-2}\): 0; 0 \\ \cline{1-1}  & Nsc: 2.54 & Nsc 2.49 \\ \cline{1-1}  & Nts: 20 & Nts: 20 \\ \cline{1-1}  & R: 4.60 & R: 4.64 \\ \hline \multirow{6}{*}{C\({}_{\rm E}\) = 100 g/100 mL} & \(10^{-0}\): 0; 0 & \(10^{-0}\): 0; 0 \\ \cline{1-1}  & \(10^{-1}\): 0; 0 & \(10^{-1}\): 0; 0 \\ \cline{1-1}  & \(10^{-2}\): 0; 0 & \(10^{-2}\): 0; 0 \\ \cline{1-1}  & Nid: \(<\)0.10 & Nid: \(<\)0.10 \\ \cline{1-1}  & Nts: 0 & Nts: 0 \\ \cline{1-1}  & R: \(>\)7.04 & R: \(>\)7.03 \\ \hline \end{tabular}  
* Mean \(\pm\) SD (n = 9): Nts—the number of units remaining after the test is performed; R—reduction in the number of microorganisms during the test; C—concentration of preparation from \(B\), _perndula_; C—concentration of ethanol.  
\end{table} 
Table 11: _Cont._able [13; 49; 50]. The authors of this study [13] analyzed birch essential oil buds obtained by hydrodistillation using a Clevenger apparatus. Its qualitative and quantitative composition was determined by GC-MS, and the analysis identified 27 compounds, mainly sesquiterpene hydrocarbons (about 79%) and oxidized sesquiterpenes (about 15%), representing about 94% of all identified essential oil components. The most abundant compounds were germacrene D (about 22%) and \(\delta\)-cadinene (17%) [13]. In this study [50], the chemical composition of bud extracts from two white birch species, i.e., _Betula pubescens_ [PERSON] and _Betula pendula_ [PERSON] (which may be a promising source of compounds with cytotoxic activity against various cancers), was assessed by GC-MS. These extracts were obtained by three distinct procedures: supercritical CO\({}_{2}\) extraction, washing of the exudate covering the whole buds, and extraction of the ground buds with diethyl ether. The chemical composition of _B. pubescens_ and _B.