Melanin is responsible for the colour of human skin, hair and eyes, and generally, more melanin reflects a darker colour.
LHMW has been previously studied for its ability to improve skin barrier function and increase skin-moisturising factors, but not on melanin production.
In this current study, researchers at Hoshi University and Asahi Calpis Wellness tested mouse cells and found that LHMW could suppress melanin production, showing promise as a cosmetic with clinical applications in humans.
The study was conducted on mouse melanoma B16 cells, which are used widely in studying melanogenesis (melanin production).
B16 cells are known to show increased melanin production and tyrosinase activity when treated with α-melanocyte-stimulating hormone (α-MSH), which is known to induce melanin production.
The study was funded by Asahi Calpis Wellness and published in the Nutrients journal.
Suppress melanin production
Researchers treated B16 cells with α-MSH to stimulate melanin production to double that of the control.
But when co-treated with 3% LHMW, the amount of melanin stimulated by α-MSH was significantly suppressed to almost the same level as that of the control.
These results confirmed that LHMW could suppress melanin production when stimulated by α-MSH, and could be a useful cosmetic material for the development of a skin-brightening agent.
Proteins and enzymes
The researchers added that the suppression of melanin production by LHMW was determined to be caused by its inhibitory activity against tyrosinase.
Melanogenesis is known to be controlled by enzymes in the tyrosinase family.
Researchers then further investigated if the inhibitory effect of LHMW on tyrosinase activity was due to suppression of protein expression.
They reported that LHMW reduced the levels ofTRP1 and DCT – both mportant proteins for melanin production.
Researchers also studied the protein microphthalmia-associated transcription factor (MITF), which is involved in the transcription of tyrosinase, TRP1 and DCT.
In α-MSH treated B16 cells, MITF expression was significantly decreased after adding LHMW.
Although this study showed that LHMW has a suppressive effect on melanin production, its active ingredient remains unclear.
Researchers speculate that the peptides found in whey may be a potential mechanism. Whey is rich in peptides and proteins, and the L. helveticus CM4 strain used in this study has strong proteolytic activity and decomposes milk proteins to produce many peptides during fermentation.
Another possible mechanism could be whey protein’s antioxidant effects.
Oxidative stress promotes melanin synthesis, and antioxidants help counter melanin production. Many skin brightening agents in the market contain antioxidants.
“Our results show that LHMW suppresses melanin production, which is suggested to involve inhibition of the expression of the tyrosinase gene family by lowering the MITF expression level. LHMW may have promise as a material for cosmetics with expected clinical application in humans.”
Researchers said this study presents a potential novel function of LHMW on the skin, and recommended future studies to explore its functions. “It will be possible to clarify the usefulness of LHMW by searching for active ingredients and comparing with regular milk whey and other lactic acid bacteria-fermented milk whey.”
“Lactobacillus helveticus-Fermented Milk Whey Suppresses Melanin Production by Inhibiting Tyrosinase through Decreasing MITF Expression”
Authors: Nobutomo Ikarashi, et al.