The structural breakdown of the cell walls of plant raw materials and the hydrolysis activity of microorganisms during the fermentation carried out affect the increase in the content of polyphenols, flavonoids, organic acids, proteins, ceramides, amino acids, biological enzymes, and antioxidants in the fermentation medium [19]. As a result, the product obtained after the fermentation of plant raw materials shows increased biological efficacy and bioavailability with reduced cytotoxicity [18]. Fermentation of plant extracts (blueberry fruit in the presence of the lactic acid bacteria _Lactobacillus plantarum_ and _Lactobacillus fermentum_ and black tea with kombucha) confirms the presence of phenolic compounds in the fermentation medium [20]. The fermentation medium with kombucha yerba mate extract showed that polyphenols such as chlorogenic acid and caffeoyl derivatives, as well as flavonoids and xanthine, may indicate the biological potential of the fermented plant extract for dermatological applications [21]. Polyphenolic compounds have gained attention due to their possible beneficial implications for human health, such as the treat ment and prevention of cancer, cardiovascular disease, mental deterioration associated with aging, and neurodegeneration [18; 22]. The fermented plant extract obtained from _Magnolia denudata_ flowers in the presence of _Pediococcus acidilactici_ KCCM 11614 had higher anticancer activity than the unfermented plant extract against human gastric adenocarcinoma (AGS) cells and human colon cancer (LoVo) cells [23]. Plant extracts obtained by fermentation of _Rhus verniciflua_ bark exhibited anticancer activity against the colon cancer cell line HCT-116 and showed the ability to induce apoptosis and inhibit the hedgehog pathway [24]. Dual fermentation of _Ophiopogon japonicus_ extract against _Cordeyces militaria_, _Bifidobacterium longum_, _Lactobacillus plantarum_, and _Enterococcus ficecium_ yielded a fermented extract that can prevent cardiovascular disease associated with vascular smooth muscle cell (VSMC) proliferation and migration [25]. Moreover, the fermented plant extract obtained from ginseng in the presence of _Aspergillus usamii_ showed higher anticancer activity against human hepatoma cells (HepG2) and the human colon cancer cell line (DLD-1) compared to the unfermented ginseng extract [22; 26]. In our previous study, the extract and bio-ferment were obtained from ground and defatted seeds of spotted thistle _Silybum marianum_. Their antioxidant activity was evaluated using DPPH, ABTS, and FRAP techniques, while total polyphenol content was measured using the Folin-Ciocalteu method. High antioxidant activity was found for both the extract (0.91 mmol \(\mathrm{Trolox/L}\)\(\pm\) 0.2) and the bio-ferment (1.19 mmol \(\mathrm{Trolox/L}\)\(\pm\) 0.2), which was evaluated by the DPPH technique. The resulting cosmetic raw materials were incorporated into hydrogel (H) and organogel (O) vehicles to obtain cosmetic formulations with antioxidant activity. We then evaluated the in vitro permeation through porcine skin of the main components contained in the obtained cosmetic raw materials, such as silibinin and taxidilin, which are part of the silymarin complex. For comparison, we also used pure silymarin (S). Of the formulations tested, H-S showed the most significant penetration of taxidilin, with a cumulative permeation of 87.739 \(\pm\) 7.457 \(\mathrm{\SIUnitSymbolMicro g}\)/\(\mathrm{cm}^{2}\). Finally, biodegradation tests of prepared formulations containing cosmetic raw materials and silymarin were also conducted. Tests on the effect of cosmetic formulations on aerobic biodegradation showed a good level of degradation of the prepared formulations, some of which (O-B and O-S) were classified as readily degradable (OECD) [14]. For this article, we focused on identifying polyphenolic compounds and lactic acid contained in the obtained bio-ferments. Phenolic acids, as antioxidants, can mitigate the harmful effects of UV radiation and oxidative stress [27].