Wound healing is a repair system which heals damaged tissue caused by external factors and is essential for maintaining biological homeostasis. Wound healing is impaired by aging. Topical agents and cosmetics have been used for the purpose of promoting wound healing. Herbal materials such as Aloe vera, Panax ginseng and Angelica acutiloba, which have been traditionally known to have beneficial effects on skin wound healing, are included in their formulations. In the process of epidermal wound healing, migration, proliferation, and differentiation of keratinocytes are indispensable, and many studies on the molecular mechanisms of epidermal wound healing have been reported. However, there are few reports about molecular mechanisms of herbal materials on epidermal wound healing effects. In this study, we focused on Paeonia albiflora root extract because it has been utilized in topical agents for skin wound care. Therefore, we examined promoting effects on migration, proliferation, and differentiation by Paeonia albiflora root extract in keratinocytes. As a result, Paeonia albiflora root extract promoted migration and proliferation, but it did not influence differentiation. The promoting effects of Paeonia albiflora root extract on migration and proliferation are caused by the increase of β-defensin-3 expressions and promoting ATP production and by the shortening of the S phase in the cell cycle, respectively. Furthermore, paeoniflorin, one of the components of Paeonia albiflora root extract, had the same effects except for the shortening of the S phase as the extract. In conclusion, it was suggested that Paeonia albiflora root extract and paeoniflorin could have promoting effects on epidermal wound healing.

The microbiome and its components on the skin and in the environment contribute to the maintenance of skin homeostasis. Here, we examined the effect of the continuous application of lipopolysaccharide (LPS), a gram-negative bacterial component, on skin sensitivity and water retention on the facial skin of 11 human subjects. To analyze the mechanism of this effect, we used the human keratinocyte cell line HaCaT to examine whether selected genes related to barrier function or tight junctions change upon LPS stimulation in vitro. Lactic acid sting tests of 11 subjects with sensitive skin showed that the use of a lotion containing LPS derived from Pantoea vagans (LPSpv) relieved the sensation of skin irritation. Additionally, stratum corneum hydration increased, and transepidermal water loss decreased in these test subjects. In HaCaT cells, stimulation of 1 μg/mL LPSpv promoted cell proliferation. RT-qPCR revealed that stimulation of 100 ng/mL LPSpv significantly increased the gene expression of filaggrin and fibronectin, which are related to barrier function, and of claudin 1, related to tight junctions. Collectively, these results suggest that LPSpv enhances epidermal barrier function.

Polymer films, which reproduce the functional properties of human skin, are emerging as innovative solutions to many skin problems. These films, referred to as second skins, not only serve as a physical barrier to environmental insults but also impart an aesthetic appearance to the skin. Despite being essential components in the cutaneous barrier, lipids have never been included in the second skin films. Here we show that wearable and transparent second skin can be prepared as a polymer dispersed liquid crystal (PDLC) film, where lipid materials are contained as a lamellar liquid crystalline (LC) phase. The lipid materials are mixtures of phytosterol, stearic acid, and lecithin or ceramide, which can be dispersed as lyotropic LC microdroplets in a polymer matrix. The PDLC film can be topically applied as a cosmetic cream (PDLC emulsion), and consequently forms on human skin as a substrate. Structural (X-ray diffraction, XRD), thermal (differential scanning calorimetry, DSC), and surface (atomic force microscopy, AFM) characterizations reveal that our PDLC film has human skin-like features. Notably, the PDLC film can act as an effective barrier against evaporative water loss and carbon pollutants. In a human study (n=10), we have demonstrated that the hydration, adhesion, mechanical, and aesthetic properties of the PDLC film are superior to those of control polymer films. We mainly attribute this in vivo performance to a unique hydration mechanism, whereby the lamellar LC dispersion generates a water concentration gradient and regulates the water content in the PDLC film. Taken together, our beauty film prepared by the PDLC approach is a highly functional cosmetic and potentially serves as a second skin barrier.

Long-lasting effect plays a crucial role in evaluating the performance of makeup products. Various film formers are used to obtain this effect, including commonly used fluorine-containing, silicone-based, and acrylic film formers. Owing to their excellent amphiphobic (lipo/hydrophobic) properties, fluorine-containing film formers possess notable long-lasting effects when compounded. However, the environmental concerns associated with the use of fluorine limit the use of fluorine-containing film formers in the cosmetics industry. Therefore, in this study, we have developed a fluorine-free new film former, namely MPC-Si polymer, possessing a biocompatible branch due to the 2-methacryloyloxyethyl phosphorylcholine (MPC). Herein, we confirmed the properties of MPC-Si polymers by the contact angle and surface free energy of the film, thereby verifying its higher amphiphobic performance than that of conventional film formers, such as fluorine-containing film formers. Additionally, MPC-Si polymers were insoluble in various solvents after film formation. This may prevent makeup deterioration, which typically occurs due to sweating or sebum secretion. In addition, the film surface was observed to be substantially flat without characteristic unevenness. The phosphorylcholine group of the polymer exists near the surface of the film, which plays an important role in the amphiphobic performance mechanism of the film. Therefore, the foundation containing MPC-Si polymer was found to have a significantly higher lipophobic performance than a fluorine-containing film former and exhibited excellent long-lasting effects and sensoriality. Furthermore, we are strongly convinced that this new proposal is one of the answers that considers environmental issues.

As a method of coloring skin care cosmetics, adding either synthetic or plant-derived dyes is common. However, the desired color tone is limited by the type of pigment, and adverse effects on the skin are also a concern depending on the choice of synthetic dye. In addition, these dyes have the drawback that they easily fade over time, and for this reason, ultraviolet absorbers and chelating agents are often added to prevent fading. However, there is likewise a concern over the safety of these stabilizing components. Therefore, in order to provide a highly safe liquid cosmetics with a good color that reflects the product concept, we focused on colloidal crystals in which particles are regularly arranged in a medium and have a crystal structure, and tried to develop a material that exhibits a beautiful auroral color. In this study, a technique using depletion force was adopted as the method to obtain the stable colloidal crystal composition which consists of linear polymer and micro gel particles in water. In this system, particles are decentralized because there is an interaction between particles, which is caused by osmotic pressure from the concentration difference of linear polymer between depletion area and bulk. Polyacryl amide or hydroxyethyl cellulose was used as the linear polymer, while used micro gels were synthesized from acrylamide and isopropyl acrylamide. As a result, the reflection spectrums of the colloidal crystal compositions were observed in the visible light region depending on the particle sizes of the micro gels. We have succeeded in developing a colloidal crystal formation technology consisting of polymers that are stable and safe regardless of existing salt, alcohol, or surfactant. Using the technology, aurora-colored water-based gel cosmetics were prepared. It was confirmed that the compositions containing a gelling agent were stable without sedimentation at room temperature for 6 months.

In Japan, the environment changes depending on the season. In particular, the amount of UV rays increases in summer and the humidity decreases in winter. UV rays and dryness cause oxidative stress inside the skin, leading to various skin troubles. Therefore, it is important to suppress oxidative stress on the skin regardless of the season. We focused on leaves of olive (Olea europaea L.), which have excellent antioxidant properties but are discarded when pruning the branches to grow the fruit. Olive leaf extract promoted glutathione synthesis in normal human epidermal keratinocytes (NHEK). Next, we conducted a long-term clinical trial for one year. The lotion containing 2% olive leaf extract increased the brightness of the skin (L^* value) in summer and decreased transepidermal water loss (TEWL), which is an index of skin barrier function, in winter. In addition, olive leaf extract promoted mRNA expression of kallikrein (KLK) 5 and KLK7, which are enzymes involved in stratum corneum desquamation, in NHEK. Olive leaf extract also promoted mRNA expression of serine protease inhibitor Kazal-type 5 (SPINK5), a gene encoding a KLK inhibitor. From the above results, we considered that olive leaf extract is a cosmetic material that can improve skin condition regardless of the season by its antioxidant effect and stratum corneum condition-improving effect.

We have developed a new white powder, titanium bis (hydrogen phosphate) (INCI name: Titanium Bis (Hydrogen Phosphate). This titanium bis (hydrogen phosphate) (hereinafter, referred to as titanium phosphate) is a flat plate-like particle having a smooth surface and an aspect ratio of about 8. Since the particles are synthesized using a hydrothermal reaction, the particle size distribution is very sharp and the particle size can be arbitrarily controlled in the range of 0.3 to 7 μm. As to optimizing particle size, by checking the correlation between three properties─particle size, hiding power and soft focus property─we confirmed the particle size of 1 μm works best. Using 1 μm titanium phosphate, we found ‘easiness of spreading’ and ‘blurring the appearance of wrinkles’ ranked highest in the sensory evaluations regarding a powder foundation formulation. Based on the above, this developed titanium phosphate is highly anticipated as a brand-new white functional powder.