## 3 Results and Discussion
### Cytotoxicity and Proliferation  
Studied juices subjected to in vitro gastrointestinal digestion and absorption showed a cytotoxic effect on examined cell lines (Table 1). Cytotoxicity levels for juice of young shoots of red cabbage were lower than those observed in the juice of mature cabbage (Table 1). The cytotoxicity results for treatment with both juices were the lowest for the PNT-2 normal prostate cell line (Table 1). In the current study, we observed that juices subjected to in vitro gastrointestinal digestion and absorption statistically significantly (\(p\leq 0.05\)) inhibited the proliferation of DU145 and LNCaPP cell lines compared to the untreated control (Figure 1). Additionally, it showed that the juice of young shoots decreased the proliferation of study cell lines more effectively than the juice of mature cabbage (Figure 1). After 24 h of incubation of DU145 cancer cells with both juices, proliferation significantly decreased (\(p\leq 0.05\), Figure 1). Proliferation was reduced by approximately 32% and 27% for treatment with the juice of young shoots and of mature vegetables, respectively (Figure 1). The results for LNCaPP prostate cancer cell line were prominent and showed a high level of sensitivity to both juices. Statistically significant (\(p\leq 0.05\)) inhibition of proliferation by 44% and 37% was observed after 24-h incubation of cells with the digested and absorbed juice of young shoots and of the vegetable at full maturity, respectively (Figure 1). Interestingly, PNT-2 normal prostate cells did not show a reduction in proliferation after treatment with both juices (Figure 1). No changes in proliferation were observed for PNT-2 normal prostate cells. Consequently, it was decided not to study mechanisms of cell death. We obtained similar results in our previous studies, while testing the fresh juices of the tested vegetable juice of young shoots reduced the proliferation of both cell lines more effectively than the juice of mature cabbage [11]. [PERSON] et al. [20] determined that aqueous extracts of cabbage sprouts had high anti-proliferative activity against HepG2 human hepatocarcinoma cells and CT26 mouse colorectal cancer cells. In our previous research, we showed that the fresh juice of young shoots of white-headed cabbage decreased the viability of MCF-7 breast cancer cells [21]. [PERSON] et al. [22] revealed that juice of white cabbage showed the highest antiproliferative activity in HL-60 cells. [PERSON] et al. [23] observed that red cabbage was one of the most active cruciferous vegetables, with complete inhibition of the proliferation of most cancer cell lines (also PC3 prostate cancer cell line). Other research on the cytotoxicity effect of red cabbage extract showed a decrease in the viability of human A-549, HT29, and HCT116 cell lines [24].  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**DU145 Cytotoxicity [\%]** & \multicolumn{2}{c}{**LNCaP Cytotoxicity [\%]**} & \multicolumn{2}{c}{**PNT-2 Cytotoxicity [\%]**} \\ \hline ys d + a vs. & mv d + a vs. & ys d + a vs. & mv d + a vs. & ys d + a vs. & mv d + a vs. \\ UC \(\pm\) SD & UC \(\pm\) SD & UC \(\pm\) SD & UC \(\pm\) SD & UC \(\pm\) SD & UC \(\pm\) SD \\ \hline
6.44 \(\pm\) 2.51 & 7.05 \(\pm\) 2.88 & 7.27 \(\pm\) 1.53 & 7.9 \(\pm\) 1.95 & 4.09 \(\pm\) 1.43 & 5.37 \(\pm\) 1.74 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Cytotoxicity of studied juices.  
A reduction of cell growth and an induction in cell death are two major means to inhibit tumor growth. Apoptosis is a gene-directed type of cell death and has become the major indicator through which chemopre and chemotherapeutic factors inhibit the growth of cancer cells. There is increasing evidence that apoptosis plays a major role as a defense against cancer, so understanding its mechanism has important implications in the prevention and treatment of many cancers [25]. Thus, we investigated whether studied juices may be involved in the induction of apoptosis, apart from cell proliferation inhibition.