## 4 Discussion  
In recent years, there has been an observed desire to explore innovative, efficient, and secure cosmetic formulations containing active ingredients with multiple effects. Additionally, cosmetic formulations containing mainly \"natural\" ingredients are perceived as safer compared to \"synthetic\" ingredients. One of the potential sources of valuable secondary metabolites used in cosmeology (as well as dermatology) are raw materials [33]. Extracts obtained from plant materials and fermented raw materials (i.e., innovative bio-ferments) are characterized by their antioxidant, anti-inflammatory, and anti-aging effects [40,47]. The fermentation of milk thistle using organic molasses and a mixture of _Lactobacillus_ strains showed that the bacterial strains can produce lactic acid (in an amount of 5.60 g), as evidenced by our acidity (215.00 \(\pm\) 1.00 mmol COOH/L) tests of the obtained bio-ferment (Table 2) and studies by other authors [48]. Our study showed that the bio-ferment showed the highest antioxidant activity via the DPPH, ABTS, and FRAP methods, the highest polyphenol content (via the Folin-Ciocalteu method), and higher chelating activity of Fe\({}^{2+}\) ions (Table 2). The high antioxidant activity indicates that lactic fermentation increases the antioxidant activity of the fermented raw material. Studies by other authors have shown that fermenting plant raw materials in the presence of a carbon and energy source (for example, sucrose) increases lactic acid production [49]. The antioxidant activity of the extract and bio-ferment was evaluated via the DPPH method, as well as by linoleic acid and tyrosinase inhibition. The results showed that the bio-ferment showed higher linoleic acid inhibition activity, which affects skin pigmentation, so the bio-ferments were also credited with skin-tone-equalizing properties. On the other hand, the tyrosinase inhibition test showed the best results against the bio-ferment, proving that the obtained cosmetic raw material plays an important role in inhibiting melanin production. Antioxidants contained in fermented cosmetic raw materials are good tyrosinase inhibitors [6,50,51,52]. However, for active compounds contained in the obtained cosmetic raw materials to have a beneficial effect on the skin, they must reach the deeper layers of the skin. Therefore,  
Figure 8: The phases of degradation of formulations: (**a**) O-B; (**b**) O-E; (**c**) O-S.  
assessing the penetration of active compounds through the skin is an important element in modeling cosmetic formulations [53]. The penetration degree of active substances may be different, depending on the compounds' physical and chemical properties as well as the vehicle used [54]. The primary impediment that restricts the permeation of active compounds into the skin is the _stratum corneum_ (SC), which serves to prevent excessive transdermal water loss as well as the ingress of germs and chemical substances [55; 33]. The SC is a thin membrane consisting primarily of cornified epidermal cells, while the main components are lipids, namely ceramides, cholesterol and its esters, and fatty acids [56]. The extracts obtained from plant materials and fermented raw materials (i.e., innovative bio-ferments) can play an important role (due to the presence of active substances--mainly polyphenols and lactic acid produced during fermentation by lactic bacteria) in the proper hydration of the epidermis as well as the inflammation of the epidermis and underlying layers. The evaluation of the transdermal absorption of active compounds is an important element in preparing cosmetic and dermatologic formulations [57]. The in vitro penetration was calculated in our investigation of extracts of _S. marianum_, the bio-ferment of _S. marianum_, and silymarin from various gel formulations (hydrogels and organogels). Two analyzed silymarin components, such as taxifolin and silybin, penetrated the skin from all the analyzed formulations (H-B, H-E, H-S, O-B, O-E, and O-S).