## 3 Results
### Cell Viability Assay  
The extracts obtained from the in vitro cultured and wild _C. vulgare_ plants were assessed for antitumor activity on four human cancer cell lines using the MTT cell viability assay. The effects resulting from the treatment with the extracts for 24 and 48 h on the cancer cell viability are presented in Figure 1. As evident from the presented data, the tested extracts induced statistically significant reductions in the cell viability and proliferation of the cancer cell lines compared to the untreated control cells. The observed cytotoxic effects of the extracts on all cell lines tested were concentration-dependent. The viability of HeLa, HT-29 and MCF-7 cells treated with the highest concentration of the extracts was most strongly decreased and lower than 15% at both time intervals. The extracts obtained from in vitro cultured plants showed stronger antitumor activity compared to the wild plant extracts. A statistically significant difference in the cell viability of the cell lines treated with in vitro cultured and wild plant extracts was observed for the HeLa cell line treated with extracts at a concentration of 500 \(\mu\)g/mL for 24 and 48 h, as well as with a concentration of 250 \(\mu\)g/mL for 48 h and MCF-7 cells treated with 500 \(\mu\)g/mL for 48 h and HepG-2 cells treated for 48 h with concentrations of 250 \(\mu\)g/mL, 500 \(\mu\)g/mL, and 1000 \(\mu\)g/mL. Moreover, the antitumor effects of the in vitro plant extracts increased with the increase in exposure time, while, at some concentrations, the viability of the HeLa and MCF-7 cell lines treated with the extracts of wild plants for 48 h was even slightly increased compared to the 24 th h. The strongest time-dependent increase in cytotoxicity was observed for the HepG-2 cells treated with extracts from in vitro cultured plants. The viability of hepatocellular carcinoma cells treated with the highest concentration of this extract was 50% and 14.9% at the 24 th and 48 th h, respectively. Compared to control untreated cells, both tested extracts induced a statistically significant reduction in the cell viability of HT-29 colorectal carcinoma cells at all concentrations tested, while in HepG2, HeLa and MCF-7 cell lines, significant cytotoxicity of both extracts was established at concentrations higher than 125 \(\mu\)g/mL (HepG2), 250 \(\mu\)g/mL (HeLa) and 250 (24 h) and 500 (48 h) \(\mu\)g/mL (MCF-7). \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{3}{*}{**Sample**} & **Total** & **Total** & **ORAC,** & **HORAC,** \\  & **Polyphenols,** & **Flavonoids,** & **\(\mu\)mol TE/g** & **\(\mu\)mol GAE/g** \\  & **mg GAE/100 g** & **mg RE/100 g** & **DW** & **DW** \\ \hline \multirow{2}{*}{
\begin{tabular}{c} in vitro \\ cultured plants \\ \end{tabular} } & \multirow{2}{*}{22402 \(\pm\) 812 a  } & \multirow{2}{*}{3689 \(\pm\) 190 a  } & \multirow{2}{*}{6119 \(\pm\) 195 a  } & \multirow{2}{*}{1538 \(\pm\) 89 a  } \\  & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Total polyphenol and flavonoid content and antioxidant activity of in vitro cultured and wild-growing _C. vulgare_ plants. The non-tumor human keratinocytes HaCaT cell line was used as a control cell line to assess the selectivity of the cytotoxicity toward cancer cells (Figure 2). The plant extracts had considerably lower cytotoxic effects on the non-tumor cell line HaCaT compared to all the tumor cell lines, especially at the 24 th h and 1000 \(\mu\)g/mL. In the non-tumor cell line, the 24 th h and 1000 \(\mu\)g/mL are much lower than the 1000 \(\mu\)g/mL. The 24 th h and 1000 \(\mu\)g/mL are much lower than the 1000 \(\mu\)g/mL. statistically significant differences between the effects of the wild and in vitro plant extracts were found only at the 48 th h after treatment with the highest concentration. In contrast to tumor cells, normal HaCaT cells appeared to be more sensitive to the effect of the wild plant extract.