Organic UV filters utilized in sunscreen have been developed targeting more efficient UV protection in their history. Sunscreens in the early days focused on prevention of sunburn mainly caused by UVB; thus organic UVB filters became the first commercial examples of synthetic organic UV filters. Among them, Ethylhexyl methoxycinnamate (EHMC) became most popular due to balanced performance and handling advantages. In the 1970s, Butyl methoxydibenzoylmethane (BMBM) was commercialized as the first organic UVA filter, reflecting increased awareness of photoaging mainly caused by UVA. Meanwhile, however, the photostability of EHMC and BMBM had been discussed more often. Therefore, photostability is considered an important characteristic in the molecular design of new-generation organic UV filters. In addition to conventional oil/water soluble organic UV filters, aqueous dispersion of particulate organic UV filers became available. Due to aqueous dispersion, these particulate organic UV fitters provide water phase protection, which efficiently prevent UV light from passing through holes originating from the water phase. These particulate organic UV filters can also provide so-called “Triple Action” efficient UV protection through the combination of absorption, reflection and multi-scattering. In addition to properties and effects, modern UV filters must satisfy broad needs of product safety and regulation from the viewpoint of sustainability. An overview of recent regulatory updates related to organic UV filters is briefly summarized here.

The signs of facial skin aging include spots, wrinkles, and sagging. In particular, the proportion of women who are concerned about sagging skin and the nasolabial folds increases with age. The causes of these skin features have been shown to involve changes in tissues that are deeper than the dermis. Techniques approaching the deep tissues have been used to date; however, the invasiveness and the issues related to the convenience for the users hampered their introduction as a daily beauty regimen. To solve these issues, we focused on physical stimuli from the oral cavity and verified the effects in vivo and in vitro. We developed a device that applies vibration stimuli and the massaging method of stretch stimuli. We tested the short-term effects of these in humans, which showed a thinning effect on the nasolabial folds visually. The same stimulation method was tested for its continuous effect, and the result showed an improvement in appearance and the internal matrix density. Furthermore, when the stimulation effect on dermal fibroblasts was tested, it was suggested that collagen production was accelerated. These results suggested that the physical stimulation method that we developed this time effectively improves the nasolabial folds. We believe that this method can be a novel beauty regimen of anti-aging care that can be introduced as a daily care regimen for ordinary people for its minimal invasiveness and convenience compared to other existing treatment methods.

It is known that the basic value of a makeup remover is its ability to remove makeup and deliver the resulting feeling of freshness. Additional consumer needs that are being addressed to supplement and heighten the product experience include putting no burden on the skin during removal, not dripping during use, being easy to wash off, and not needing to be followed up with face wash. It has been assumed that a foamy makeup remover would be a strong candidate to address all these issues. However, a foam-type remover has been impossible to create previously since makeup contains a considerable amount of hydrophobic solids, such as hydrophobized powders, waxes, and hydrophobic film formers. These ingredients, as well as the oily substances from makeup removers, which are necessary to sufficiently remove makeup, break up the foam by intruding into its membrane. We have succeeded in hybridizing an anion/amphoteric surfactant mixture into a bicontinuous microemulsion (BME) phase, which is known to have an excellent ability to remove makeup. The solution forms dense foam by dispensing it from a pump foamer, achieving a highly effective foam-state makeup remover for the first time. Furthermore, we found an interesting phenomenon whereby makeup is spontaneously dissolved upon contact with the foam-state remover. This phenomenon seems to be caused by moderate foam breaking upon contact with makeup, leading to a supply of surfactant molecules from the air/remover interface to the makeup/remover interface, followed by a flow of water, resulting in makeup removal. By this novel function of foam, achieved by the foam-state BME phase, a novel makeup remover that fulfills all the consumer needs listed above was successfully developed.

Tactile sensation at the time a cosmetic product blends onto the skin is an important aspect of cosmetic evaluation. However, a general method to evaluate the texture change over time during the application of cosmetics has not been established. To catch the dynamic texture perception of cosmetic products, we applied the method of Temporal Dominance of Sensations (TDS) which is a popular methodology in sensory evaluation of foods and beverages. In our method, panelists apply skincare products on their hand and choose the sensory attributes by their gaze behavior to avoid interfering with their application behavior and tactile perception. To evaluate several skincare products used in this experiment, we selected sensory attributes through in-depth interviews and the results of factor analysis about the fitness between words and texture perception during application. Using our method, we visualized the texture changes between three kinds of skincare products during application. Because panelists in this experiment were naïve to the TDS method, they were required to get used to it and we set practice trials before starting the evaluation. Then we confirmed that the order of dominant tactile sensations appearing during application was relatively consistent for a panelist (avg. approximately 2/3 trials).These results showed that this TDS method is appropriate for cosmetic evaluation.

We aim to provide cosmetics that appeal to users' “sensibility” and have accordingly developed cosmetics based on a sensibility evaluation. As the research subject, we chose exfoliating lotions. Our method correlates the visualized psychological structure with measured physical quantities. To visualize the psychological structure when using an exfoliating lotion, we selected appropriate evaluation words and conducted a one-month usage test. Using factor analysis, we evaluated nine factors that are related to the value judgments of users using the exfoliating lotions. Next, we analyzed the causal relationships between these factors via structural equation modeling and modeled the psychological structures of the users. The model fit indices were satisfactory. The subconsciously important perceptions appeared to be “frictional feeling” and “wiped-off feeling,” both of which are derived from the tactile impression imposed by the wiping motion. Next, to identify physical quantities that can independently affect the “frictional feeling” and the “wiped-off feeling,” we measured the dynamic friction coefficient and the time profile of the frictional force for 12 types of exfoliating lotions. Using the dynamic friction coefficient, the two factors could not be individually evaluated; On the other hand, we extracted the eight-dimensional vibrational feature quantities in the time-frequency domain from the time profile and correlated them with the factor scores of the two factors in a multiple regression analysis. The factor scores were estimated with high accuracy. Each factor corresponded to a different vibrational feature, confirming that the factors are physically independent. This result suggests that both factors can be simultaneously increased by controlling the frictional force. Using this result as a predictive index of the tactile impression, it was possible to do sensibility evaluation of an exfoliating lotion that had a superior texture at the time of wiping; this could not be achieved in the past.

Consumers are demanding a reliable antiperspirant product because they tend to sweat more as the number of hot days increases. In our previous studies, we devoted our efforts to effective utilization of aluminium chlorohydrate (ACH), a general-purpose antiperspirant active ingredient, in which we aimed to deposit a larger amount of ACH on the skin to improve the antiperspirant effect of an ACH-based product. In this study, we newly focus on various physical properties of an ACH gel because ACH works to occlude sweat glands by forming a gel when it reacts with sweat. We have finally developed a new technology to maintain the gel state in a wide range of pH, leading us to improve the antiperspirant efficiency. Evaluating the gelation behavior of ACH in an ACHsweat coexisting system, we found that the bicarbonate ion promoted and lactic acid obstructed the gelation. This implies that other inorganic acid ions and organic acid ions also affect the gelation of ACH. Therefore, we screened for various components to promote the gelation and found that sulfate ions showed the greatest influence on the gelation, inducing the highest antiperspirant efficiency. SAXS analysis of the ACH-sulfate ion coexisting gel demonstrated that sulfate strengthens the gel network comprising ACH nanoparticles. In conclusion, the formation of the stronger ACH gel assisted by sulfate ions greatly enhances the antiperspirant efficiency of the ACH-based product.

To obtain insight into the relationship between blood capillaries in the skin and aged appearance, we developed a novel microscope for observing the capillaries in the forefront of the skin, the papillary dermis. The new device utilizes a carefully designed skin contact apparatus that controls the local flow of blood, enabling quantitative observation of the capillaries in the papillary dermis of facial skin, as well as other parts of the body. We observed and quantified capillaries on cheeks of 34 healthy female volunteers in their 20s to 50s, and found that the areal number density of capillary loops shows a decreasing trend with age. Statistical analysis of the relationship between the areal number density of capillary loops in the papillary dermis and cutaneous properties was conducted. Dullness factor, wrinkle factor, and net elasticity were found to be significantly correlated with the areal number density of capillary loops. From these results, we presumed that these capillaries play a critical role in preventing aged appearance. In order to search for materials with capillary formation potential, we established a novel co-culture in vitro system consisting of human umbilical vein endothelial cells (HUVECs) and mesenchymal stem cells (MSCs). From screening of materials in our in vitro system, we found tripeptide-1 as a novel active ingredient that stimulates capillary formation.

We have developed a new cleansing cream formulation with a good-feeling and excellent stability by defining the effect of polyol on the crystal structure of the interface. In recent years, the qualities required for make-up remover have included “cleansing capability” and “moisturizing feeling”． The cleansing cream is an O／W emulsion in which a large amount of oil droplets is dispersed in a small amount of water phase, and since it is easy to add water and a moisturizer, we considered that this formulation is suitable for satisfying the above two required qualities. So far, cleansing cream formulations have been focused on interfacial science for stabilization. Nevertheless, these formulations have been limited by their instability at low temperature. Therefore, we sought out for the mechanism of destabilization at low temperature by investigating the crystal structure of the interface, and aimed to develop a stable formulation. As an interesting result, it was found in the wide-angle X-ray diffraction measurement that the destabilized formulation showed a polymorphic transition from the α -polymorph to the β'-polymorph. It was clarified that the addition of a highly hydrophobic polyol can suppress the polymorphic transition at the interface and the crystal growth at low temperature, and thereby stabilize the formulation.