## 3 Results  
### Characteristics and Differentiation of the Chemical Composition of Bearberry Leaf Extracts  
The analyzed extracts varied in terms of their chemical composition even though the plants came from pine forests, i.e., six sites/patches that were very similar to each other in terms of the vegetation species composition (Table 1). The cluster analysis of the chemical composition of the bearberry leaf extracts showed two separate groups (Figure 1). The ethanolic and aqueous extracts are clearly distinguished among the studied groups. The percent similarity of the two groups is ca. 86%; however, the similarity of the first cluster representing the ethanolic extracts (Et) is ca. 96.5% and that of the second cluster representing aqueous extracts (Aq) is ca. 95%.  
The two groups of extracts had different chemical profiles (Table 1). In the case of the total phenolic content (TPC), the concentration of these metabolites in Et was ca. 60% higher than in Aq, which is in agreement with earlier studies [24]. Similarly, the total flavonoid content (TFC) and the concentration of methylarbutin (mARB) were significantly higher in Et. In turn, the concentration of hydroquinone (HQ) was ca. 70% and that of corilagin  
\begin{table}
\begin{tabular}{l c c c c} \hline  & \multicolumn{2}{c}{**Et**} & \multicolumn{2}{c}{**Aq**} \\ \hline
**Phytochemicals** & **Mean** & **SD** & **Mean** & **SD** \\ \hline Total flavonoids (mg GAE g\({}^{-1}\)) & 3.39 \({}^{\text{a}}\) & 0.317 & 2.58 \({}^{\text{b}}\) & 0.424 \\ Total phenolics (mg GE g\({}^{-1}\)) & 271.68 \({}^{\text{a}}\) & 8.889 & 170.26 \({}^{\text{b}}\) & 21.528 \\ Arbutin (mg g\({}^{-1}\)) & 88.79 \({}^{\text{a}}\) & 13.757 & 87.08 \({}^{\text{a}}\) & 17.764 \\ Hydroquinone (mg g\({}^{-1}\)) & 9.22 \({}^{\text{b}}\) & 1.583 & 13.09 \({}^{\text{a}}\) & 1.047 \\ Ursolic acid (mg g\({}^{-1}\)) & 9.32 \({}^{\text{a}}\) & 0.727 & 0.00 \({}^{\text{b}}\) & 0.000 \\ Hyperoside (mg g\({}^{-1}\)) & 5.16 \({}^{\text{a}}\) & 1.087 & 4.43 \({}^{\text{a}}\) & 1.175 \\ Methylarbutin (mg g\({}^{-1}\)) & 5.98 \({}^{\text{a}}\) & 0.990 & 2.21 \({}^{\text{b}}\) & 1.336 \\ PGG (mg g\({}^{-1}\)) & 3.39 \({}^{\text{a}}\) & 0.317 & 2.58 \({}^{\text{a}}\) & 0.424 \\ Picein (mg g\({}^{-1}\)) & 1.54 \({}^{\text{a}}\) & 0.109 & 1.66 \({}^{\text{a}}\) & 0.180 \\ Oleanolic acid (mg g\({}^{-1}\)) & 1.25 \({}^{\text{a}}\) & 0.138 & 0.00 \({}^{\text{b}}\) & 0.000 \\ Corilagin (mg g\({}^{-1}\)) & 0.85 \({}^{\text{b}}\) & 0.379 & 1.77 \({}^{\text{a}}\) & 0.079 \\ \hline \end{tabular}
\end{table}
Table 1: Content of phytochemicals in ethanolic (Et) and aqueous (Aq) bearberry leaf extracts. Mann–Whitney U test; values designated by different letters are significantly different (_p_ < 0.05).  
(COR) was ca. 100% higher in Aq in relation to Et. The presence of torsolic acid (UA) and oleanolic acid (OA) was confirmed solely in Et, and the concentrations of arbutin (ARB), hyperoside (HYP), picein (PIC), and penta-O-galloyl-\(\beta\)-D-glucose (PGG) in both extract types were similar. The amount of the main component arbutin (ARB) depended on the ecological habitat conditions and the season [16]. Therefore, the noticeable variability in their concentration was probably determined by the habitat conditions. The abovementioned research results indicate that, in most cases, the bearberry leaves meet the requirements (>70 mg g\({}^{-1}\)) specified in the European Pharmacopoeia [31]. The concentration of this component determined in Et and Aq is the minimum content given by [PERSON] [16] from populations growing in northern locations in Spain, i.e., in harsher conditions--relatively higher altitudes characterized by lower mean temperatures, higher annual precipitations, and lower global radiation levels.