## 3 Results and Discussion
### Elemental Profile of SN Extracts
Another significant field of application of this method might be for the environmental protection, where this plant might be used in the process of phytoremediation. Phytoremediation represents alternative remediation technology based on usage of the plants for removing pollutants and/or render them harmless [22]. Plants used for this purpose are classified according to their tolerance toward metals and accumulation response on contaminated soil into three groups: excluders, indicator plants, and hyper-accumulators. Excluders restrict metal uptake through plant root with the exception in the case of extreme concentrations of the metals. In the case of an indicator plant, accumulated metal concentration is relative to their level in the soil, while hyper-accumulators concentrate the metals regardless of the metal levels in the soil [23; 24]. A study regarding the heavy metals content in wild plant growing near ironwork in Zenica (Bosnia and Herzegovina) showed that stinging nettle possesses strong affinity toward the metals [25]. Taking those results into account, this plant may be used as a natural remover of polluting elements in soil and underground water, which represents one of the main issues these days in the field of environmental protection. Besides the role of neutralizer, the plant itself may be used as an indicator of elements' presence in a particular area by direct analysis of plant root and leaves or, like in this particular case, by preparing the extracts. Classification of the investigated extracts (observations) based on their mineral content was done by principal component analysis (PCA). All the parameters given in the Table 3, except for the Hg, were used for the PCA. The first two principal components (PCs) represented 92.19% of the initial variability of the data (PC1--69.64% and PC2--22.55%). Table 4 shows the factor loadings of the PC1 and PC2. PC1 was correlated with the K, Mg, Fe, Cu, Mn, Zn, Cr, Sn, Ni, Pb, and As, while PC2 with Na, Ca, and Cd (absolute value of factor loadings > 0.6). Different extracts of stinging nettle leaves are presented in the PC1 vs. PC2 plane (Figure 1). The extracts were clustered into the three groups based on their mineral content. The first group consists of UAE and MAE, the second is MAC, and the third is SE (Figure 1). \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Element**} & \multicolumn{2}{c}{**Factor Loading**} \\ \cline{2-3}  & **PC1** & **PC2** \\ \hline Na & \(-\)0.5924 & **-0.6781** \\ K & **0.9952 * & 0.0976 \\ Mg & **0.9646** & \(-\)0.2450 \\ Ca & 0.5623 & **-0.8158** \\ Fe & **0.9139** & 0.2531 \\ Cu & **-0.9450** & \(-\)0.2677 \\ Mn & **0.9375** & \(-\)0.2706 \\ Zn & **0.8920** & 0.0429 \\ Cr & **-0.9438** & \(-\)0.3303 \\ Sn & **-0.8851** & \(-\)0.4650 \\ Ni & **0.9728** & 0.2243 \\ Pb & **-0.7196** & 0.4985 \\ Cd & \(-\)0.2665 & **0.9025** \\ As & **-0.7413** & 0.5597 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Factor loadings of principal component (PC) 1 and 2 obtained by principal component analysis of mineral content of different extracts of the stinging nettle leaves’ extracts. Similarity of the results obtained by the UAE and MAE might be the possible reason for their clustering in the first group. Those two extraction techniques showed better results than the conventional ones.