Clarifying Newly Found Causes for Rough Skin: Development of New Technology for Trapping Unsaturated Fatty Acids*1 Contained in Sebum

• Japanese Version

Kao Corporation's Skin Care Products Research Laboratory, Material Science Research Laboratory, Analytical Science Research Laboratory and Biological Science Research Laboratory have discovered that the unsaturated fatty acids^*1 contained in secreted sebum have a negative effect on the skin barrier function that can cause dryness. By successfully developing a new technology that utilizes hydroxypropyl cellulose (HPC) which forms a sponge-like structure (Figure 1) and selectively combines with unsaturated fatty acids to trap them on the skin, Kao expects to be able to suppress contact between unsaturated fatty acids and skin with this technology.

While sebum secreted from our skin works as a moisturizer to protect it from dryness, a survey on skin problems revealed that roughly 40% of people who report having oily skin feel dryness during the winter months immediately after washing their face, the same response as people who report having dry skin^*2 .

This prompted Kao to examine the correlation between skin surface sebum and skin functions to understand the effects of sebum on skin conditions.

• *2 Surveyed by Kao between May and June 2021, targeting 129 Japanese females with different skin types between the ages of 20 and 55

Furthermore, it was also discovered that when HPC was processed to easily dissolve in water, it was effective in gelling and trapping more OA (Figure 5).

Further analysis was conducted to clarity the mechanism by which HPC selectively gels OA. The results showed that hydrogen bonding occurs between HPC and OA. Analysis of membranes using a scanning electron microscope showed that membranes formed by HPC and OA had a unique sponge-like structure (Figure 1). Kao also speculates that the gelling may also have occurred because a significant amount of OA was taken into the spaces of the sponge-like structure formed by the bonding of HPC and OA. It is expected that trapping OA on the skin surface may reduce its contact with the skin, thereby reducing its negative effect on the skin.

Kao clarified in this research that the quantity and quality of sebum can affect the skin barrier function and water content. It was found that skin with a certain quantity of sebum and a higher ratio of unsaturated fatty acids has lower skin barrier function and water content. In the process of research, it was also discovered that HPC could be used as an effective means to trap unsaturated fatty acid, a component of sebum that negatively affects the skin. Kao will apply these findings to the development of new skincare products from a new standpoint of solving rough skin and skin dryness caused by sebum.

Kao creates high-value-added products and services that provide care and enrichment for the life of all people and the planet. Through its portfolio of over 20 leading brands such as Attack, Bioré, Goldwell, Jergens, John Frieda, Kanebo, Laurier, Merries, and Molton Brown, Kao is part of the everyday lives of people in Asia, Oceania, North America, and Europe. Combined with its chemical business, which contributes to a wide range of industries, Kao generates about 1,550 billion yen in annual sales. Kao employs about 35,400 people worldwide and has 136 years of history in innovation. Please visit the Kao Group website for updated information.

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