## 4 Discussion
Moreover, in addition to the transformation of phenolic compounds, fermentation induces condensation reactions between flavanols and anthocyanins, forming anthocyanin-flavanol pigments: in particular, cyanidin-3-glucose-ethyl-epicatechin. Fermentation increases the levels of the flavanones naringerin, eriodictyl, and naringerin from eriodictyl-7-O-glucose and naringerin-7-O-glucose, respectively. During fermentation, bioconversion of flavones, that is, the conversion of bacialin and wogonoside into their more bioavailable, aglycone forms, bacialin and wogonin, respectively, can occur. The bioconversion of isoflav from glycosidic to aglycone form is also observed during the fermentation of raw plant materials. During the bioconversion of daidzein, glycitrin, and genistein 7-O-glucose, free daidzein, glycitrin, and genistein are formed. The deglycosylation of flavanols during fermentation results in the release of kaempfer, kaempfer 3-glucose, quercetin, and quercetin 3-glucose from ruitin (quercetin 3-rutinoside) [49; 65; 66; 69; 70]. Cytotoxicity analyses showed that both unfermented and fermented extracts of _S. aromaticum_ L. can increase the viability of skin cells in vitro (Figures 7-10). However, taking into account the possibility of the cytotoxic effects of extracts and fermentations obtained from this plant in higher concentrations, when considering its use as a raw material for the production of various preparations applied to the skin, the appropriate concentration should be selected. The possibility of cytotoxic effects of _S. aromaticum_ on skin cells was also confirmed by [PERSON] et al. [71]. During studies using fibroblasts, they indicated the cytotoxic properties of both the oil from this plant and the eugenol itself. In contrast, in our study, we did not observe any cytotoxicity on fibroblasts treated with fermented stem extracts in the concentration range of 0-100,000 ug/mL (Figure 8), suggesting that FSEs from _S. aromaticum_ L. can prolong skin cell viability. However, [PERSON] et al. [72] did not observe any cytotoxicity on fibroblasts treated with clove extracts in the concentration range of 0-200 ug/mL [72]. These results indicate that cytotoxicity is strictly dependent on both the plant part and the phytochemicals it contains [58; 59]. So far, there are no literature reports on the cytotoxicity of fermentations from _S. aromaticum_ L.; therefore, this work indicates for the first time the potential use of FSEs in the cosmetics and pharmaceutical industries. The major components in FSE from _Syzygium aromaticum_ L. were eugenol, \(\alpha\)- and \(\beta\)-caryophyllene, eugenyl acetate, and caryophyllene oxide (Figure S2). Our _S. aromaticum_ L. fermented extract contained similar classes of compounds (phenylpropanol, sesquiterpenes, carboxylate ester, and oxygen derivative of sesquiterpenes) as the non-fermented extract from _S. aromaticum_ L. analysed by [PERSON] et al. [73]. _Syzygium aromaticum_ L. essential oil (from buds) was richer in diethyl phthalate, cadinene, \(\alpha\)-copaene, 4-(2-propenyl)-phenol, clavicol, and \(\alpha\)-cubehene, while the extract isolated from clove leaf contained benzyl hexahydropyrrol [1,2-A] pyrazine-1,4-dione; 3,5 dihydroxy-4,4 dimethyl-2,5 cyclohexa-dien-1-one;nitrophenylazo tert-butyl sulphide, and 2-propylpiperidine as the main components [34; 74]. This comparison suggests that essential oils and extracts obtained from different parts of the same plant (buds, leaves, and stems) may have different chemical compositions, which may result in different biological activities. The constituents potentially responsible for the biological activity of the fermented extract from _S. aromaticum_ L. are eugenol, eugenyl acetate, and \(\alpha\)- and \(\beta\)-caryophyllene [34; 35]. The analgesic, antioxidant, anticancer, antiseptic, antidepressant, antispasmodic, antiinflammatory, antiviral, antifungal, and antimicrobial effects of eugenol, which is the main component of clove oil, have been documented [36; 75].