## 4 Conclusions  
One of the goals of the food industry is to use as few organic solvents as possible. Therefore, our study was limited to water as a solvent. With Design Expert pro 11, optimal parameters for extraction performance were determined to achieve the highest percentage of antioxidant activity. The concentration of extracts required to achieve 50% inhibitory effectiveness, total phenols, and proanthocyanidins was determined. Furthermore, a study of the influence of extracts on WM-266-4 melanoma cells was performed. A high percentage of antioxidant activity AA (\(c\) = 5 mg/mL) = 87% was measured in the curcuma extract and a low concentration (EC\({}_{50}\) = 0.708 mg/mL) was required to achieve 50% inhibition. Multiple studies have shown that curcuma is a potent antioxidant source that combats free radicals in the body and has significant potential to act as an antitumor agent. Within the frame of our research, we observed that extract of turmeric significantly influences metabolic activity at the lowest extract concentration of 0.001 mg/mL. Curcuma extract shows two concentration ranges where metabolic activity is significantly reduced: at about 50% MA and 20%. Goji berry extract has the lowest influence on metabolic activity. The highest concentration (100 mg/mL) of goji berry extract had an influence on metabolic activity (MA = 25%). However, therewas no significant change with other concentrations. Grape marc and seed exhibited 84% antioxidant activity. The percentage of total phenols is higher than 50%. When cell metabolic activity is concerned, compared to the control, it was observed that the extracts inhibited the metabolic activity of the tested cells at all concentrations. Therefore, they reduced or decreased the metabolic activity of cancer cells. Grape marc and seed extract at 20-100 mg/mL concentration have the most significant influence on metabolic activity. The results showed that horsetail extract causes significant change in metabolic activity even for the lowest concentration present, 0.001 mg/mL. It is assumed that the reason for this is the high content of antioxidants AA (\(c\) = 5 mg/mL) = 79% and total phenols GA = 33.49 mg/g in the horsetail extract. Rosemary extract has a similar influence on metabolic activity compared to horsetail extract, because even for the lowest concentration present (0.001 mg/mL), significant inhibition of metabolic activity of the tested cells was noted. The cause of the high metabolic activity of WM-266-4 cells is probably high levels of antioxidants AA (\(c\) = 5 mg/mL) = 89% and total GA phenols = 90.10 mg/g extract, as antioxidants and phenols have a beneficial effect or prevent oxidative stress of the cells. The optimal process conditions for the preparation of extracts from selected natural materials (Curcuna, Goji Berry, Grape marc and seeds, Horsetail and Rosemary) were determined. The obtained extracts decreased the rate of melanoma cell division (WM-266-4). Further, it would be interesting to check in more detail whether the division only stopped or even apoptosis of these melanoma cells may have occurred. We plan to expand the research to at least three other melanoma cell lines to test anti-tumour effects. It would also be interesting to check the content of the potential bioactive compounds in the discharged fractions, since agricultural residues have already been shown to have the potential for an abundant source of natural antioxidants suitable for further development [99]. Furthermore, it would be necessary to check what is the influence of the extracts on the healthy cells. Therefore, this should be a point for further investigation. [PERSON] and [PERSON] performed most of the experimental work, [PERSON] performed an extensive literature search and data evaluation together with [PERSON]. [PERSON] and [PERSON] wrote most of the paper; [PERSON] and [PERSON] devised the content of the review and supervised the writing. All authors have read and agreed to the published version of the manuscript.