## 3 Results and Discussion
### The Effect on VERO Cells
The data for metabolic and proliferative activity was correlated at r = 0.639, which indicates a relationship between these parameters in cells exposed to the test samples. _J. regia_ extracts have been previously shown to be cytotoxic to various types of cells, including cancer cells [39]. Triterpene compounds have been identified as components of green walnut husks responsible for cytotoxic effects. Their structure has an important effect on antitumor activity [23]. Polyphenols exert cytotoxic or antitumor activity through range of mechanisms, e.g., induction of cell apoptosis, changes in the cell cycle or via the modification of signaling pathways [40]. On the other hand, polyphenols belong to phytochemicals that are produced by plants as a part of their defense against environmental stress. They are able to protect cells against oxidative stress induced by toxic substances [41]. The cytotoxic effects of phytochemicals can be a source of side effects when using drugs of natural origin and functional food products. Hence, it is important to test such products for performance within acceptable concentrations and selectivity of action [42; 43]. \begin{table} \begin{tabular}{c c c c c c} \hline \hline
**Sample** & **48 h** & **125 \(\upmu\)g mL\({}^{-1}\)** & **250 \(\upmu\)g mL\({}^{-1}\)** & **500 \(\upmu\)g mL\({}^{-1}\)** & **1000 \(\upmu\)g mL\({}^{-1}\)** \\ \hline \multirow{2}{*}{1} & PA & 112.93 \(\pm\)2.04 * & 92.52 \(\pm\) 0.01 *** & 50.45 \(\pm\) 4.87 ** & 12.55 \(\pm\) 1.92 *** \\  & MA & 78.43 \(\pm\) 2.72 *** & 77.13 \(\pm\) 3.18 *** & 78.30 \(\pm\) 1.07 *** & 67.93 \(\pm\) 6.30 *** \\ \hline \multirow{2}{*}{2} & PA & 85.55 \(\pm\) 7.98 & 64.74 \(\pm\) 3.70 ** & 39.41 \(\pm\) 0.53 *** & 10.08 \(\pm\) 3.01 *** \\  & MA & 79.77 \(\pm\) 9.88 *** & 89.48 \(\pm\) 3.48 * & 64.08 \(\pm\) 7.92 *** & 77.50 \(\pm\) 6.85 *** \\ \hline \multirow{2}{*}{3} & PA & 96.15 \(\pm\) 3.01 * & 66.77 \(\pm\) 0.90 *** & 24.91 \(\pm\) 1.32 *** & 14.63 \(\pm\) 0.78 ** \\  & MA & 63.27 \(\pm\) 5.43 *** & 74.21 \(\pm\) 3.77 *** & 59.36 \(\pm\) 8.86 *** & 83.72 \(\pm\) 7.21 ** \\ \hline \multirow{2}{*}{4} & PA & 85.50 \(\pm\) 2.39 * & 80.60 \(\pm\) 6.55 * & 64.51 \(\pm\) 4.89 ** & 19.25 \(\pm\) 0.74 *** \\  & MA & 101.33 \(\pm\) 5.51 & 94.36 \(\pm\) 3.69 & 84.64 \(\pm\) 2.94 ** & 76.07 \(\pm\) 2.14 *** \\ \hline \multirow{2}{*}{5} & PA & 93.38 \(\pm\) 5.33 & 124.73 \(\pm\) 4.28 * & 58.08 \(\pm\) 3.21 ** & 23.37 \(\pm\) 0.42 *** \\  & MA & 85.56 \(\pm\) 4.55 * & 91.94 \(\pm\) 4.32 *** & 69.31 \(\pm\) 1.48 *** & 65.52 \(\pm\) 6.35 *** \\ \hline \multirow{2}{*}{6} & PA & 68.74 \(\pm\) 5.94 * & 50.13 \(\pm\) 0.70 *** & 35.90 \(\pm\) 0.23 *** & 14.91 \(\pm\) 1.33 *** \\  & MA & 83.64 \(\pm\) 3.48 ** & 68.37 \(\pm\) 3.72 *** & 68.98 \(\pm\) 1.67 *** & 57.92 \(\pm\) 1.64 *** \\ \hline \multirow{2}{*}{Control} & PA & \multicolumn{4}{c}{100 \(\pm\) 3.85} \\  & MA & \multicolumn{4}{c}{100 \(\pm\) 2.44} \\ \hline \hline \end{tabular}  PA—proliferative activity; MA—metabolic activity; Control—untreated cells, 1  
The cytotoxic effect may be beneficial when applied to cancer cells, but a balance between therapeutic effect and safety of healthy cells must be kept [44; 45].