Polyethylene glycol (PEG)-modified silicone is widely used as a surfactant for water-in-oil (W/O) emulsions, but its emulsion stability at high temperatures is generally considered low. This is due to the fact that dehydrated PEG becomes hydrophobic and is removed from the oil-water interface. On the other hand, cyclodextrins (CDs) are water-soluble cyclic molecules with hydrophobic cavities and are generally known to recognize low-molecular-weight substances. We have found a remarkable emulsion-stabilizing effect of PEG-modified silicone with HLB 4.5 (PEG-MS) in combination with α-CD in a W/O emulsion system at high-temperature storage. In this study, we investigated the emulsion stabilization mechanism by rheological measurements, thermal analysis, and interfacial layer viscosity measurements using an amphiphilic spin probe. As a result, it was shown that PEG-MS and α-CD form a supramolecular complex (PEG-MS/α-CD complex) driven by hydrophobic interaction, which is considered to contribute to emulsion stabilization by being efficiently oriented at the oil-water interface. Furthermore, the PEG-MS/α-CD complex was indicated to form more stably at higher temperatures. This means that dehydration, an unstable factor in W/O emulsion systems using PEG-MS, can rather be utilized. This approach is expected to reduce the amount of surfactants and oil thickeners, and therefore, to create W/O formulations with both emulsion stability and good touch properties.

Prolonged ultraviolet (UV) exposure causes skin photoaging with clinical features of wrinkles, loss of elasticity, and roughness. Histologically, photoaging is characterized by the accumulation of abnormally disorganized elastic fibers in the upper dermis, and various post-translational modifications are assumed to be associated with this process. Protein tyrosine nitration, which is mediated by reactive nitrogen species formed by nitric oxide and superoxide, is one of the post-translational modifications that has increasingly been recognized as a functionally significant protein modification. This study aimed to investigate the involvement of protein nitration in abnormal elastin accumulation and skin photoaging. Immunohistochemical staining of skin sections from elderly women revealed that abnormally accumulated elastin in the photoaged dermis (cheek) was more strongly colocalized with nitrotyrosine than elastin in the chronologically aged dermis (buttock). Moreover, an immunoprecipitation assay showed that dermal fibroblasts exposed to UV-A induced tyrosine nitration of elastin. Experimental nitration of elastin fibers altered the physical properties of elastin, with the formation of large multimeric assemblies of human recombinant tropoelastin and curled and aggregated bundles of elastin fibers, resulting in enhanced stiffness and decreased elasticity of elastin. In addition, nitrated elastin showed resistance to degradation by elastase secreted by neutrophils and fibroblasts. Furthermore, the nitrotyrosine-reducing agent, clove extract, inhibited peroxynitrite-induced elastin aggregation and improved human skin elasticity. These results suggest that elastin nitration caused by UV exposure leads to abnormal elastin accumulation, which alters the mechanical properties of the skin and results in the progression of photoaging. Therefore, this study proposes nitration as a potential novel target for preventing skin photoaging.

The sudden drop in estrogen levels during menopause causes a variety of generalized complaints such as hot flashes, sweating, and fatigue in addition to skin symptoms such as irritation, pruritus and dryness. However, few studies have focused on these symptoms, especially skin symptoms, and much is still unknown about their causes. In this study, we first investigated the correlation between the severity of menopausal symptoms (Simplified Menopausal Index: SMI) and variety of skin problems by a questionnaire survey conducted on 176 women aged 45 to 55 who were aware of menopausal symptoms. In addition to hot flashes and sweating, many skin problems related with dry skin and barrier dysfunctions including pruritus were correlated with SMI scores. Moreover, subjects with high SMI showed increased levels of transepidermal water loss compared with those with low SMI. Thus, we examined the usefulness of hyaluronic acid fragments (molecular weight in the range of 50000-110000) as a novel mean to relieve menopausal skin symptoms, mainly targeting dysfunction of the epidermis. Hyaluronic acid fragments accelerated both proliferation and differentiation of cultured human epidermal keratinocytes, although hyaluronic acid with smaller molecular weight (under 10000) enhanced the proliferation but not the differentiation and hyaluronic acid with high molecular weight (over 1000000) supported the differentiation but not the proliferation. Finally, topical application of hyaluronic acid fragments restored impaired permeability barrier function and increased hydration of the stratum corneum in subjects with high SMI scores, accompanying with an increase of satisfaction with their skin condition. These results that hyaluronic acid fragments could be useful for alleviating skin symptoms during menopause.

Hairdo and make-up are considered to be some of the most important factors that can greatly influence people's appearance, and many people think that make-up is relatively more important than hair-style in changing impressions. However, it has not been empirically clarified yet whether hair-style or make-up has more influence on people's impressions. In this study, we conducted two experiments using 6 evaluation words to measure and compare the effects of hair-style and make-up on impressions, and analyzed the data using ANOVA and multiple regression analysis. The results showed that both hair-style and make-up had a strong effect on impressions for all evaluation words. In fact, hair-style had nearly twice the partial regression coefficient as make-up for “clean.” In addition, interactions were observed between hair-style or make-up and gender in some rating terms, indicating that there are differences in the degree of influence of hair-style or make-up on impressions between male and female observers. We also categorized the evaluation words that hair-style or make-up correlated strongly with, and identified the impression change characteristics. By clarifying the influence of hair-style on impressions, we expect to explore further possibilities of the influence on the impression of hair-style and to develop and market hair care products that appeal better to consumers.

Perm styles are attractive to many people. However, trying a perm is difficult because it dam- ages the hair and scalp; moreover, restoration to the original hair style is impossible. In this study, we aimed to develop an adhesive hair styling agent that forms hair bundles with wire-like hardness for fixing the curl shapes to create perm styles without the perm. Accordingly, an aerosol foam agent containing waxes created perm styles without the perm. The results of the hair styling mechanism verifications showed that the agent is adhesive and can be applied uniformly but doesn't have hardness. Microscopic observation of the formulation-treated hair surface confirmed fine uneven structures comprising wax crystals. Furthermore, the results of a hair combing test revealed that it can strongly hook hairs with each other. These characteristics may significantly contribute to create perm styles.

The stratum corneum, the outermost layer of the skin, is composed of corneocytes and intercellular lipids. The intercellular lipids mainly consist of ceramides, fatty acids, cholesterol, and cholesterol esters. These components form a bilayered lamellar structure, making it challenging for substances to penetrate. While oleic acid is known for its skin penetration enhancing properties, there is limited information about the skin penetration enhancing effects of oleic acid esters that focus on their structure. In this research, we investigated the potential skin penetration enhancing effects of various oleic acid esters, obtained by esterifying oleic acid with different alcohols, using excised human skin with ceramides as the target substance. As a result, we identified isobutyl oleate as a novel oil component with potential for cosmetic ingredient applications due to its skin penetration enhancing capabilities.