Repeated exposure to UV radiation can induce cutaneous damage leading to permanent structural degeneration of the dermal extracellular matrix and formation of visible wrinkles. It is not so easy to efface severely UV-damaged skin, because the degenerated abnormal structure of that skin is usually fixed by tight crosslinkings. So, we think that one of the important approaches to the anti-wrinkle skin care is the treatment of photodamaged skin in the early stage. However, it is difficult for most cosmetic users to perceive their dermal UV damage. In the present study, we investigated the possibilities of two non-invasive measurements of skin mechanical properties as convenient biomarkers of degeneration of the extracellular matrix. The condition of the three-dimensional structures of dermal collagen fibers, which depends on the degree of UV damage, correlated with a mechanical parameter measured by the Resiliometer we developed. Accumulation of denatured elastic fibers (elastosis) induced by photoaging correlated with certain mechanical parameters measured by the Cutometer. These findings suggest that dermal structural changes associated with photoaging can be assessed noninvasively using these devices.

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Blood flow stagnation is said to be an important factor for the incidence of dark eye circles, but there are few reports which have studied dark eye circles and the relationship to blood flow. We have examined dark eye circles dermatologically using a non-invasive method and made clear the factor related to it. We have also studied the effect of newly developed cosmetics on improvement of dark eye circles. Melanin and hemoglobin content, hemoglobin oxygen saturation and blood flow rate were measured to compare dark eye circles with a normal control. An increased amount of hemoglobin and decreased hemoglobin oxygen saturation were observed at the site of dark eye circles. We also observed that the blood flow rate was slow at dark eye circles in comparison with cheek. From these results, blood flow stagnation seems to be one of the factors that could induce dark eye circles. In addition, the increase of melanin at dark eye circles was also observed in older subjects. It was considered that not only congestion but also an increase of melanin content in the skin could induce dark eye circles. On the basis of these results, we developed anti-dark eye circle cosmetics that can improve blood circulation, reduce melanin content and maintain high moisture retention in the skin. After three weeks' usage of this product, it was confirmed that dark eye circles were improved, judging from the result of non-invasive instrumental measurements.

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A typical formula for shampoo containing cationic polymers and anionic/amphoteric surfactants exhibits liquid-liquid phase separation under certain conditions when the shampoo is diluted with water upon the actual use in bathroom. The lower dense phase is considered to be an insoluble complex formed with the cationic polymer and mixed surfactants. Generally, this associative liquid-liquid phase separation is called “coacervation” and the phase of complex is called “coacervate.” Although it is well known that the usage texture of shampoo is influenced by coacervate, there are only a few reports about their relationship. In this work, we studied the properties of coacervate and its effect on the usage texture of shampoo, particularly focusing on the effect of the cationic polymer structure. We prepared five different model shampoos that contain various cationic polymers, and studied the effect of the characteristics of the polymers on the condition of the complex formations, the amount of coacervate, the rheological properties and the adhesive behavior of coacervate on the surface of damaged hair. It was found that both the structure and the degree of substitution of cationic polymer drastically changed the condition of coacervation. Moreover, the cationic polymers showed remarkable effect on the rheological properties and the adhesive behavior of the coacervate on the damaged hair. These results implied that we could control the usage texture of shampoo by choosing proper cationic polymers to control coacervation.

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OLIGOMARINE^® is a complex of minerals obtained from seawater. In a cell culture system, OLIGOMARINE^® stimulated not only the cell activation but also the collagen synthesis of fibroblasts. In addition, OLIGOMARINE^® might have accelerated the keratinization since the expression of suprabasal markers, such as involucrin and transglutaminase, were promoted in cultured normal human keratinocytes. Furthermore, the water-holding properties and permeability barrier function of the stratum corneum were enhanced by using lotion containing OLIGOMARINE^®. These results suggested that OLIGOMARINE^® would be useful as a humectant for the prevention or improvement of dry skin.

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