Cosmetics, since ancient times, have been attributed a huge role, being regarded as products contributing to the ideal of a beautiful body. A beautiful body was associated with the beauty of the soul, and it was believed that a beautiful person was also a noble one. Conversely, ugliness was seen as a synonym for evil and transgression [1]. Therefore, ancient man, with the use of fragrant herbs and appropriate minerals, prepared perfume oils, perfumes, and colored makeup products. In the period between antiquity and the modern era, women used elaborate beauty treatments—the texts of the visionary and mystic Saint Hildegard of Bingen contain numerous recipes for masks and moisturizing and firming creams [2].Plants have been used by humans since the earliest times, from being a dietary fundamental to their huge role in cultural and aesthetic life. Plant motifs have been used as decorative elements of homes, tombs, and temples. However, one of their most important applications was their use in healing, everyday hygiene, and cosmetics [3].

During the present study, historical databases (papyri.info, Thesaurus Linguae Graecae, Thesaurus Linguae Latinae) were analyzed, based on which, plants with desirable care properties, used since antiquity, were selected. These plants are Silphion (Latin: Silphium), Arugula (Eruca sativa L.), and Watercress (Nasturtium officinale). Of the aforementioned, Silphion deserves special attention, and its properties are the focus of this paper, as ancient sources repeatedly mention this plant in the context of many disease treatments, as well as its beautifying action.

Silphion in the medicine of the ancient world existed as a unique plant—a Cyrenian natural wonder. Its value was measured by its weight of silver, and export to the markets of the Mediterranean world was a royal prerogative. The use of this plant in the treatment of a wide variety of conditions, namely tracheal pain, tetanus, epilepsy, sciatic nerve pain, abdominal pain., and hair loss [4], made it a subject of research. According to ancient accounts, the Cyrenian species, Silphium, was most likely extinct. However, related species with similar properties were still used, including the identically named Silphium, but also: Laserpitium, Hittite, and Asafoetida. Muhammad ibn Zakariya al Razi (865–925) described two types of hiltit (Silphium)—one nicely fragrant, the other stinking [5]. The counterpart of Silphion in the modern world, in terms of morphology, is Ferula assa-foetida L.The active substance present in Ferula assa-foetida L. is ferulic acid (IUPAC: (2E)-3-(4-hydroxy-3-methoxyphenyl)prop-2-enoic acid; commonly named 4-hydroxy-3-methoxycinnamic acid, FA). It was Ferula foetida L. from which this compound was first isolated and its name comes from the botanical name of this plant [6]. In 1925, FA was chemically synthesized for the first time and its structure was confirmed by spectroscopic methods [7]. This compound exhibits skin care, anti-aging, and firming properties [8]. In addition, it is known for its antioxidant and anti-inflammatory properties, as well as its whitening effect and prevention of skin discoloration caused by photoaging [9,10,11]. It also exhibits stabilizing properties against vitamins C and E, which in aqueous solutions become sensitive to the presence of oxygen, high temperature, and UV radiation. In addition, ferulic acid increases the effectiveness of these vitamins [12]. Moreover, the latest study showed that Ferula assa-foetida L. seed oil loaded into SLN exhibits a significant cell-growth suppressive impact on the line of human stem cells causing brain cancer [13]. All possible applications of ferulic acid as an ingredient in cosmetic products are shown in Figure 1.With the development of civilization and technology, the way that plants are used in cosmetics has undergone significant changes. Today, thanks to analytical methods, it is possible to accurately identify the components of plant raw materials both qualitatively and quantitatively, which allows for precise dosages of raw materials of proven quality. The use of innovative methods for processing plant raw materials (e.g., ultrasound-assisted extraction, microwave-assisted extraction, extraction using supercritical fluid, enzymatic extraction, and micellar extraction) allows the use of new plants in cosmetic formulations that were previously of little use to cosmetologists [15].Improvement in the stability of active compounds and plant extracts is possible thanks to their incorporation into nanocapsules. The most promising carriers of active substances in cosmetic products are solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC), which are currently under intensive study [16]. These materials have several favorable functional properties, including, but not limited to: structure based on lipids well tolerated by the human body, high stability, and the ability to carry hydro- and lipo-philic compounds [17,18]. Lipid nanoparticles are also characterized by adhesive and occlusive properties, so a protective film is formed on the surface of the skin, which reduces transepidermal water loss (TEWL) and ensures the maintenance of an adequate level of hydration [19].Lipid nanoparticles are currently of great interest to researchers, and many publications have been devoted to them, e.g., [20,21,22]. SLNs were first synthesized in 1991 [23]. They are spherical particles in the size range of between 10/20 nm and 1000 nm composed of lipids that remain solid at both room temperature and body temperature. In addition, they are dispersed in an aqueous phase containing emulsifiers. Conversely, the NLC matrix is composed of both solid and liquid lipids with different spatial structures. Such lipids crystallize imperfectly and form free voids into which the active substance can be incorporated [19,24]. A single SLN structure consists of an incorporated active ingredient, a solid lipid, an emulsifier, and water [25] (Figure 2).Among the methods for obtaining solid lipid nanoparticles on an industrial scale the most significant is the high-pressure homogenization method and emulsification with evaporation or solvent diffusion [26]. The most efficient method for SLN synthesis is high-pressure homogenization (HPH) [21], which involves the pre-dispersal of the lipid phase in the emulsifier solution. In a further step, cycles of high-pressure homogenization take place several times, followed by nanoemulsion formation, cooling, and crystallization of the lipid. It should be noted that the lipid mass is pumped under high pressure (300 to 2000 bar) through a narrow space, which causes the particles to fragment to nanometer sizes. Additionally, this method sterilizes the lipid suspension by eliminating bacterial cells as a result of the high pressure. The size of the obtained nanoparticles is influenced by the type and amount of lipids and emulsifiers used, as well as the number of homogenization cycles carried out during HPH. It has been proven that the high-pressure homogenization process alone does not affect the chemical stability of the lipids underlying the nanoparticles [22]. Nevertheless, it should also be taken into account that the high pressure applied during the HPH process may induce immense shear stresses that will lead to the destruction of larger molecules of active substances incorporated into SLNs. Another limitation may be the need to apply elevated temperatures that are required to melt the lipid phase, which in turn may destabilize selected active substances. This causes some limitations in the possibility of using HPH to obtain SLNs incorporated with, for example, proteins and peptides. However, there have been reports of the successful incorporation of a peptide into the structure of an SLN using the HPH process [27].The aim of our research was to develop stable formulations of lipid nanoparticles containing an ethanol extract of Ferula assa-foetida L. Encapsulation methods were selected in such a way that the physicochemical properties of the selected extract—more specifically, the active substance contained in it, namely ferulic acid—were preserved. The use of ferulic acid in skincare and cosmetic products faces some problems related to its low stability and solubility in water. These problems can be eliminated by its encapsulation into lipid nanoparticles [28].