## 1 Introduction  
Selected plant raw materials rich in active components are commonly used in the production of natural cosmetics. The active ingredients contained in plant raw materials (i.e., polyphenic compounds, proteins, amino acids, carbohydrates, or phospholipids) show antioxidant activity and influence the appropriate hydration of the skin. Extracts obtained from selected plant raw materials are characterized by favorable skin properties, offering the potential to be used as cosmetic raw materials. Bio-ferments, which contain innovative active ingredients derived from natural plant raw materials (but also plant extracts or organic oils) during microbial fermentation, are characterized by a range of properties related to their antioxidant activity, moisturizing, or anti-allergenic effects. Bi-fermented oils, which are excellent emollients rich in active compounds, are characterized by their sebum-regulating effects. The main advantage of bio-ferments as innovative ingredients in cosmetic formulations, which are obtained by microbial fermentation, is their high biocompatibility. In addition, technological and environmental factors, such as the reduction in carbon footprint and the use of waste materials (including plant biomass), mean that bio-ferments are increasingly being used in the cosmetic industry. The microbial fermentation of plant raw materials makes it possible to obtain cosmetic raw materials with better properties regarding their biological activity, antioxidant activity, or suppression of tyrosinase than those of non-fermented raw materials (such as plant extracts). In addition, bio-ferments have great potential as innovative cosmetic raw materials with a high SPF. Plant raw materials may prove effective in the treatment of skin hyperpigmentation due to the inhibition of melanogenesis through the activation of 3-kinase [1; 2; 3; 4; 5; 6; 7; 8; 9]. Silymarin is composed of a complex of compounds, mainly flavonoids, with a high level of biological activity. Flavonolignans are formed in plants by the oxidative coupling of the flavonoid taxifolin with a coniferyl alcohol. The main compounds in the complex are silybin and isosilybin as well as silychristin and silydianin. Lesser amounts of other flavonolignans are included in the complex: isosilychristin, silymonine, slandrin, and silygermine. Silymarin and preparations containing it are often standardized for the silybin content. However, the low water solubility and the limited permeability of silymarin through the skin have significantly limited the use of this active ingredient as a cosmetic raw material in topicals. Therefore, researchers are seeking to increase the solubility of silymarin and thus increase its bioavailability. One possible solution is to incorporate this active substance into suitable cosmetic vehicles applied topically to the skin. Examples of cosmetic vehicles include gel substrates such as hydrogels and organogels--biodegradable and non-degradable vehicles of active substances devoid of their own pharmacological activity--into which the active substances can be placed. Thanks to the specific structure of the gels, they form a skeletal reservoir for the storage of therapeutic substances, released under the influence of certain external stimuli but protected from the harmful effects of the environment [10; 11; 12; 13; 14; 15; 16]. Milk thistle (_Silybum marianum_) is a native Mediterranean plant used for medicinal and ornamental purposes. Mainly the fruits of this plant are used for medicinal purposes. Silymarin, a compound from milk thistle, is non-toxic and has no adverse effects when administered orally. Silymarin, a polyphenic compound, has been found to have therapeutic effects through regenerative, antioxidant, and anti-inflammatory mechanisms. Silymarin inhibits xanthine oxidase activity and NADPH oxidase activity, affecting the oxidoreductase status of cells and signal transduction pathways. It stimulates the activation of the cell antioxidant enzymes catalase and superoxide dismutase, reducing glutathione levels.