Stearyl glycyrrhetinate SW claims to suppress inflammation to mitigate the formation of age spots therefore exhibiting whitening effects.
“The results showed that the developed stearyl glycyrrhetinate SW suppresses inflammation, which is a cause of age spots, and exhibits excellent whitening effects, and was approved by the Ministry of Health, Labour and Welfare as an active whitening ingredient,” Kosé announced in a press statement.
The active is derived from liquorice roots, an herb that is widely used in both Japanese and Chinese cultures. It has been previously understood to improve the appearance of rough skin.
The active is the result of joint research efforts between Kosé and Maruzen Pharmaceutical, a Japanese raw material supplier.
According to Kosé, the development of the active has been a decade in the making.
“In developing this ingredient, we have been conducting research for over 10 years in collaboration with Maruzen Pharmaceutical Co., Ltd., Japan's top manufacturer of liquorice and glycyrrhetinic acid derivatives made from liquorice.”
The research was driven by the need for an effective solution for age spots, which are among the top concerns for consumers, said Kosé.
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The active’s effect was verified on pigmentation caused by ultraviolet (UV) rays.
The firm tested the ingredient by applying it on skin irradiated by UV rays for 28 days and compared it to a placebo formulation under the same conditions.
It observed the production of prostaglandin E2 (PGE2), which can be stimulated by UV rays.
“The production of PGE2 was increased by ultraviolet light, but the production was suppressed by adding stearyl glycyrrhetinate SW. We confirmed that PGE2 production was suppressed in epidermal cells exposed to UV light.”
Furthermore, when melanocytes were cultured in a medium of epidermal cells that had been irradiated with UV rays, the team found that tyrosinase activity increased.
However, stearyl glycyrrhetinate SW could also suppress this activity.
“These results revealed that stearyl glycyrrhetinate SW suppresses the increase in tyrosinase activity in melanocytes by suppressing the production of PGE2 caused by ultraviolet rays. At this time, we confirmed that stearyl glycyrrhetinate SW had no adverse effect on cell growth.”
The active was tested for 12 weeks by 30 participants to have age spots. After 12 weeks, the researchers observed improvements in age spots as well as overall skin tone.
“After continuous use, the redness and uneven skin tone decreased, and the brightness and transparency of the skin significantly improved compared to before continuous use.”
The firm said it would be developing skin care products using this active moving forward.
“In the future, we will respond to the needs of customers suffering from age spots by applying this ingredient as our unique whitening active ingredient to the development of skin care products.
“We will continue to conduct research and development that can respond to customers' skin concerns with scientific evidence, such as elucidating the mechanism of action and developing useful ingredients.”