The research group had previously demonstrated that the contraction of human sweat glands pushes sweat out to the skin surface. However, its detailed mechanism and factors that could suppress sweating were not identified.
To elucidate the contraction mechanism of sweat glands and develop a new antiperspirant ingredient, the researchers collected eccrine sweat glands from human skin tissue and observed them.
It was found that connexins (CX) — proteins that constitute gap junctions (intercellular channels that allow passage of water-soluble ions and electrical signals between adjacent cells) — are expressed in large amounts on myoepithelial cells, and that gap junctions in myoepithelial cells are significantly involved in sweat gland contraction during sweating.
Among them, Connexin 43 (Cx43) was particularly abundant in myoepithelial cells.
In addition, the findings showed that sweat gland activity was suppressed by carbenoxolone (CBX), a gap junction inhibitor that blocks myoepithelial cell movement, and has a structure similar to substances found in the root of the licorice plant.
Furthermore, monoammonium glycyrrhizinate (GMA), a CBX analogue, was used to verify its antiperspirant effect on sweating caused by exercise or mental stress. Sweating behaviour was observed in real time using a sweat meter.
The results showed that applying GMA to the armpits delayed the onset of sweating, and reduced the total amount of sweat produced during 15 minutes of exercise.
The application of GMA also suppressed sweating in the palms during five minutes of mental arithmetic, indicating that GMA inhibits both thermal and psychogenic sweating in humans.
These findings represent an “unprecedented antiperspirant technology” that acts directly on the sweat glands to reduce sweating.
Mandom looks to utilise the findings to develop next-generation antiperspirants, as well as conduct more research into the treatment of sweating disorders, such as hyperhidrosis.
It is thought that the combination of this discovery with conventional antiperspirant technologies could further improve antiperspirant effects.
“Humans can efficiently regulate their body temperature by sweating. This function allows people to exercise for long periods of time. However, due to rising temperatures worldwide and socio-psychological stress, the number of people suffering from excessive sweating and the resulting unpleasant odour is also increasing.
“For those with hyperhidrosis, excessive sweating interferes with their daily lives. To address this pain point, we have been working to uncover the sweating mechanism of human sweat glands and develop new effective antiperspirant ingredients,” said Takeshi Hara, Manager of Life Science Research Group at Mandom Advanced Technology Research Institute.
This study was presented at the recent International Federation of Societies of Cosmetic Chemists (IFSCC) 2023 in Barcelona, and won the “Best Award” in the poster category.
Demand for better antiperspirants
According to Mandom, global warming and excessive sweating have become a concern in recent years not just for hyperhidrosis patients, but they are also affecting the quality of life for people without sweating dysfunctions.
Antiperspirants typically contain aluminium salts, which physically “cap” the sweat glands to decrease the amount of sweat that rises to the skin surface.
Yet, a survey held by Mandom showed that one in three antiperspirant users were not satisfied with the effectiveness of existing products, and that they are seeking improvements in the functionality of antiperspirants.
Conducted in September this year, the survey included 499 men and women aged between 20 and 59 years.
The results signify the demand and market potential for the category, which Mandom aims to capitalise on.
“In the future, we will leverage the results of our research to help improve the quality of life of consumers facing sweating-related problems,” Hara said.