## 3 Results and Discussion
### Chemical Composition of Bark and Leaves Extracts of Various Species from the Genus Salix  
Even though many research articles studied the chemical composition of bark of various _Salix_ species to a certain extent, these studies mainly focused on salicylic and salicin derivatives and only few dealt with simple phenolics in willows [10; 14; 15]. Moreover, leaves of _Salix_ species are usually considered as waste product after bark collection and are mainly not studied. It is known that waste products from plant processing represent promising sources of valuable bioactive compounds [29]. In addition, many species of willows widely distributed in nature are until present poorly studied or lack any kind of data related to their biological activities and chemical characterization. Therefore, chemical composition of bark and leaves of seven _Salix_ species was determined by HPLC and is shown in Tables 2 and 3. A representative chromatogram of _S. ampleicaulis_ bark extract is presented in Figure 2. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Compound** & _S. alba_ & _S. ampleicaulis_ & _S. babylonica_ & _S. eleaagnos_ & _S. fragilis_ & _S. purpurea_ & _S. triandra_ \\  & & & & **(mg/g of bark)** & & & & \\ GA & 0.17 \(\pm\) 0.00 a & n.d. & 0.17 \(\pm\) 0.01 a & n.d. & 0.19 \(\pm\) 0.01 b & n.d. & 0.26 \(\pm\) 0.03 c \\ CHLA & 1.65 \(\pm\) 0.17 b & 1.51 \(\pm\) 0.14 b & 1.92 \(\pm\) 0.02 b & 2.08 \(\pm\) 0.14 c & 1.54 \(\pm\) 0.01 b & 1.14 \(\pm\) 0.01 a & 1.63 \(\pm\) 0.01 b \\ PHB & 0.32 \(\pm\) 0.01 a & 0.92 \(\pm\) 0.01 b & 1.21 \(\pm\) 0.02 c & 1.24 \(\pm\) 0.01 c & 0.39 \(\pm\) 0.04 a & n.d. & n.d. \\ VA & n.d. & n.d. & n.d. & n.d. & 0.24 \(\pm\) 0.04 a & n.d. & n.d. \\ SA & 0.22 \(\pm\) 0.01 b & n.d. & 0.34 \(\pm\) 0.014 c & 0.20 \(\pm\) 0.04 b & 0.16 \(\pm\) 0.01 a & n.d. & n.d. \\ CA & n.d. & n.d. & n.d. & 0.53 \(\pm\) 0.01 a & n.d. & 1.05 \(\pm\) 0.01 b & n.d. \\ EPC & 1.17 \(\pm\) 0.05 a & 1.30 \(\pm\) 0.00 a & 2.68 \(\pm\) 0.06 d & 1.98 \(\pm\) 0.15 b & 2.57 \(\pm\) 0.09 a & 2.08 \(\pm\) 0.02 c & 1.77 \(\pm\) 0.25 b \\ PCA & 0.15 \(\pm\) 0.01 a & 1.55 \(\pm\) 0.04 c & 0.15 \(\pm\) 0.01 a & 0.14 \(\pm\) 0.00 a & 0.08 \(\pm\) 0.00 a & 1.53 \(\pm\) 0.05 c & 0.22 \(\pm\) 0.01 b \\ R & 1.75 \(\pm\) 0.03 a & 22.09 \(\pm\) 0.04 d & 1.36 \(\pm\) 0.15 a & 5.20 \(\pm\) 0.34 c & 1.26 \(\pm\) 0.04 a & 4.30 \(\pm\) 0.03 b & 1.73 \(\pm\) 0.06 a \\ Q & 0.38 \(\pm\) 0.02 a & 0.61 \(\pm\) 0.01 b & 0.52 \(\pm\) 0.00 ab & 1.28 \(\pm\) 0.04 c & 0.41 \(\pm\) 0.01 a & 1.13 \(\pm\) 0.01 c & 0.67 \(\pm\) 0.01 b \\ TCA & 0.15 \(\pm\) 0.05 a & 0.65 \(\pm\) 0.14 b & 0.57 \(\pm\) 0.01 b & 0.52 \(\pm\) 0.03 b & 0.49 \(\pm\) 0.00 b & 0.13 \(\pm\) 0.01 a & 0.53 \(\pm\) 0.03 b \\ N & 0.20 \(\pm\) 0.01 a & 0.48 \(\pm\) 0.01 d & 0.27 \(\pm\) 0.09 b & 0.38 \(\pm\) 0.06 c & 0.26 \(\pm\) 0.00 b & 0.26 \(\pm\) 0.01 b & 0.33 \(\pm\) 0.00 c \\ S & 3.99 \(\pm\) 0.18 a & 8.29 \(\pm\) 0.09 b & 3.11 \(\pm\) 2.50 a & 2.60 \(\pm\) 0.06 a & 3.47 \(\pm\) 0.04 a & 7.53 \(\pm\) 0.30 b & 2.87 \(\pm\) 0.03 a \\ \hline \hline \end{tabular}  
* n.d.—not detected; GA—gallic acid; CHLA—chlorogenic acid; PHB—p-hydroxybenzoic acid; VA—vanillic acid; SA—syringic acid; CA—caffeic acid; EPC—epicatechin; PCA—p-coumaric acid; R—rutin; Q—quercetin; TCA—trans-cinnamic acid; N—naringenin; S—salicin. Data are presented as mean of triplicate measurements \(\pm\) SD. Superscript letters within the same line indicate significant differences of means at the 0.05 level.  
\end{table} 
Table 2: Phytochemical characterization of bark extracts. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Compound** & _S. alba_ & _S. ampleicaulis_ & _S. babylonica_ & _S. eleaagnos_ & _S. fragilis_ & _S. purpurea_ & _S.