Kao hints eucalyptus and bilberry extract use in future prestige skin care line

13 Jun 2023 --- Biological Science Research Division of Kao Corporation has revealed that eucalyptus and bilberry extracts can enhance the skin barrier. The company finds that the decline of autophagy activity – cellular recycling process – in the skin adversely affects epidermal homeostasis and disturbs the formation (cornification) of the stratum corneum, which is the skin’s barrier that retains hydration.

Autophagy means “self-eating,” which is a natural process in all cells in the human body, where unwanted or dysfunctional proteins are degraded into amino acids. These amino acids are then recycled to create new proteins. When the process decreases in the skin calls, it affects skin appearance. 

“Eucalyptus and bilberry extracts have been discovered as cosmetic ingredients with the potential to enhance autophagy activity and keratinization. These will be formulated into Kao’s new prestige skin care line-up,” Keigo Kawabata, manager of biological science research, R&D at Kao Corporation, tells PersonalCareInsights. 

Research for skin health
In 2019, in consultation with Dr. Tamotsu Yoshimori, an Osaka University professor, Kao successfully measured autophagy activity using human skin tissue and reported that autophagy activity declines in chronological aging and photoaging due to ultraviolet light exposure. 

Kao investigates the changes in cornification from autophagy activation in cultured elbow skin tissue with hyperkeratosis. The research hypothesized that beneficially harnessing the skin autophagy process that naturally occurs in the human body can contribute to the health of skin cells and improve skin appearance.  

“It is easy to predict that there will be many other positive effects on the skin led by autophagy activation,” says Kawabata.

In the epidermis, keratinocytes mature and undergo cornification to form the stratum corneum – the skin’s outermost layer. In this process, components key to hydration are created, and the barrier that protects the skin from physical and chemical stressors from the external environment is also attained. 

Kao researchers compared the elbow skin and arm skin around the elbow in healthy individuals between the ages of 30 and 50 experiencing skin problems at the elbow, such as dryness and roughness. The results confirm hyperkeratosis at the elbow and suggest that lower autophagy activity may be one cause of cornification disturbance.

Eucalyptus and bilberry for skin
To further study the effects of autophagy on cornification disturbance, a reagent that activates autophagy was added to cultured elbow skin. The results show that reagent treatment in the cultured hyperkeratosis skin tissues was normalized and that proteins associated with cornification were more normally distributed than before. 

This suggests that increasing autophagy activity can help modulate disturbed cornification and healthy stratum corneum formation. Kao finds eucalyptus and bilberry extracts can better skin health.

Kao investigated which ingredients beneficially activate autophagy for healthy stratum corneum formation and found that when eucalyptus extract and bilberry extract are added to keratinocytes simultaneously, there is an increase in autophagy activity and loricrin proteins, which form and maintain the epidermis. 

“Cosmetic ingredients and technologies that promote (or inhibit) the necessary elements for suppressing skin aging have been used in general skin care cosmetics. In contrast to these, this technology will enhance the ‘intracellular environment’ for cells to fulfill their role in keratinization and other processes,” explains Kawabata. 

A portion of the research findings have been published in the International Journal of Molecular Sciences and announced at the 143rd Annual Meeting of the Pharmaceutical Society of Japan.

Kao says it will continue researching the function of autophagy in human bodies, aiming to improve its technologies to help people attain healthy-looking skin. 

“We hope that applying technology from this new perspective to cosmetics will trigger innovation in dermatological research and cosmetics development policy and vitalize the cosmetics industry,” concludes Kawabata.

By Sabine Waldeck