## 4 Discussion
In addition, other phenolic acids, such as caffe acid and ferulic acid, were detected in smaller amounts within a few hours of fermentation, indicating possible conversion between phenolic acids via chalcones. The simpler structure of these metabolites may contribute to the higher antioxidant activity of fermented jussar pulp, with an increase in oxygen radical-reducing capacity from 49.2 to 90.7% compared to the unfermented extract. Accordingly, _L. plantarum_ and _Oencoccus oeni_ deglycosylate anthocyanin glucosides into their aglycones: malvidin, delphinidin, and peonidin. Further ring cleavage released trihydroxybenzaldehyde and syringic acid (from malvidin), gallic acid (from delphinidin or demethylation of syringic acid), or vanillic acid (from peonidin) [40; 47]. The degree of anthocyanin degradation by lactic acid bacteria depends on the LAB species. The highest anthocyanin content was observed by conducting fermentation in the presence of _L. casei_ and _L. bulgaricus_, while conducting fermentation in the presence of other _L. species_ resulted in anthocyanins at lower levels. In addition, the anthocyanin content, particularly delphinidin 3-O-glucose, in the fermented orange juice was more significantly reduced by _L. rhamnus_ or _L. paracasi_ than by _L. plantarum_ or _L. brevis_. These observations may be due to variability in \(\beta\)-glucosidase or \(\beta\)-galactosidase activity, and the presence of more hydroxyl groups in delphinidin increases its susceptibility to enzymatic degradation more than that of other anthocyanins [39; 48]. The cytotoxicity of plant extracts is closely dependent on the part of the plant being extracted and the phytochemicals contained in that part of the plant material [49; 50]. When assessing the potential use of individual plant raw materials in preparations applied to the skin, it is extremely important to assess their cytotoxicity in vitro, which allows for a preliminary assessment of the validity and possibility of using the analysed plant as a cosmetic ingredient [51]. In order to assess the impact of the obtained PE and FPE from _S. aromaticum_ L. _Mytraceae_ on the viability and metabolism of skin cells, an analysis of their cytotoxicity on keratinocytes (HaCaT) and fibroblasts (HDF) was performed. As part of the analyses, the Alamar blue test was carried out, which measures the level of reduction in the non-fluorescent blue resazurin dye to the red fluorescent dye, which allows for the assessment of the level of metabolic activity of cells [25]. The results obtained in the resazurin reduction test indicated a concentration-dependent effect of the tested samples on the viability of keratinocytes and fibroblasts. This test indicated that both PE and FPE could increase skin cell viability in vitro. The strongest pro-proliferative effect in HaCaT cells was recorded at a concentration of 1.375 mg/mL (in the case of FPE), at which the viability was 119.6%, while for the extract, the most optimal concentration was 0.48 mg/mL, which increased the viability of these cells to 114.4%. In the case of HDF cells, the most optimal concentrations for FPE and PE were 1.375 and 1.196 mg/mL, respectively, for which the viability was 113.2% and 109.5%. However, note that increasing the concentration of both FPE and PE to 2.75-5.5 mg/mL and 2.39-4.8 mg/mL results in a decrease in the viability of the tested cells, indicating the cytotoxic effect of these samples at higher concentrations. In the case of the Neutral Red assay, it was shown that the effect of the tested fermented and non-fermented extracts, similarly to the first test, varies depending on the concentration of PE used and the type of cells. For keratinocytes, the use of FPE resulted in the highest viability at a concentration of 0.55 mg/mL, achieving a cell viability of 127.5%. In the case of PE, the highest cell activity (111.5%) was recorded for a concentration of 0.048 mg/mL, while with the increase in concentration, the viability gradually decreased, reaching 66.1% for a concentration of 4.8 mg/mL.