## 4 Discussion  
For several years, interest in the subject of healthy food and its impact on the human body has significantly increased in society. People are increasingly aware of the products that they consume and the fact that many diseases are diet-related, which has been confirmed by scientific studies. Consumers are choosing functional products that contain pro-health ingredients, and one of these is certainly fruit preserves that contain resveratrol. Resveratrol is also used in dietary supplements as well as in cosmetology. The reason for this may be the belief that substances of natural origin have a milder and more comprehensive effect on the body. However, it should be remembered that high concentrations of antioxidants may have a pro-oxidative effect, which could lead to a disturbance in the oxidation-reduction homeostasis of cells. Oxidative stress in neoplastic cells can lead to their damage and thus polyphenols may exhibit anti-cancer activity [16; 17]. Resveratrol cytotoxicity against C32 and Colo829 malignant melanoma cells was assessed in this study, ranging from 50 \(\upmu\)M to 1000 \(\upmu\)M. The concentration of 500 \(\upmu\)M was selected for the experiment due to the statistically significant decrease in the viability of both melanoma cells and thus its cytotoxic effect. A study by [PERSON] et al. [18] found that, at a concentration of 400 \(\upmu\)M, resveratrol was cytotoxic to head and neck cancer cells (HN-30). In addition, in the studies of [PERSON] et al. [19], it was found that, at a concentration of 200 \(\upmu\)M, resveratrol was cytotoxic to breast cancer cells. Moreover, a study by [PERSON] et al. [20] confirmed that resveratrol (100 \(\upmu\)M) also causes a decrease in the proliferation of gastric cancer cells. The resveratrol-mediated chemotherapeutic mechanism is apoptosis, which is associated with the activation of p53, a tumor suppressor, and induces the activation of the death receptor Fas/CD85/APO-1 in diverse cancer cells [21]. Resveratrol has also been demonstrated to activate the expression of p21 and p27, which promotes cell cycle arrest in melanoma cells [22]. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **MDA [mmol/10\({}^{6}\) Cells]** & **ABTS [mmol/10\({}^{6}\) Cells]** \\ \hline
**C** & 31.65 \(\pm\) 1.52 & 24.65 \(\pm\) 1.03 & 411.6 \(\pm\) 28.1 & 380.3 \(\pm\) 11.9 \\ \hline
**R [500 \(\upmu\)mol/L]** & 44.4 \(\pm\) 2.7 \({}^{\rm a}\) & 30.02 \(\pm\) 1.08 \({}^{\rm a}\) & 565.3 \(\pm\) 33.2 \({}^{\rm a}\) & 506.7 \(\pm\) 33.1 \({}^{\rm a}\) \\ \hline
**SMF (0.7 T)** & 29.01 \(\pm\) 0.9 \({}^{\rm b}\) & 25.26 \(\pm\) 1.7 \({}^{\rm b}\) & 420.2 \(\pm\) 21.4 \({}^{\rm b}\) & 379.9 \(\pm\) 27.5 \({}^{\rm b}\) \\ \hline
**SMF (0.7 T) + R** [500 \(\upmu\)mol/L]** & 33.69 \(\pm\) 1.83 \({}^{\rm b,c}\) & 27.51 \(\pm\) 1.3 \({}^{\rm a,b}\) & 455.9 \(\pm\) 25.6 \({}^{\rm b}\) & 370.4 \(\pm\) 24.2 \({}^{\rm b}\) \\ \hline  & **C32** & **Colo829** & **C32** & **Colo829** \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Effect of resveratrol and an SMF on the MDA concentration and total antioxidant status in the melanoma cell cultures (C32, Colo829). The results are presented as the mean \(\pm\) SD; \({}^{\rm a}\)\(p\) < 0.05 vs. C (control); \({}^{\rm b}\)\(p\) < 0.05 vs. (R) resveratrol; \({}^{\rm c}\)\(p\) < 0.05 vs. SMF. Many scientific reports have suggested that if the amount of reactive oxygen species in a cell is low, the defense mechanisms are activated and the activity of antioxidant enzymes increases, whereas high ROS levels lead to the impairment of the enzymatic defense mechanisms, which results in a decrease in the activity of the antioxidant enzymes [23; 24]. The addition of resveratrol to the culture of melanoma cells disturbed the oxidation-reduction balance of cells and the oxidative stress increased. The anti-cancer properties of resveratrol are probably due to its pro-oxidative effect on cells. Research has confirmed that polyphenols including resveratrol exhibit antioxidant and pro-oxidative properties that depend on the doses that are used.