Effect of lactic acid bacteria-fermented milk whey on melanin production

Melanin is generated in the melanosomes of melanocytes and is an important factor determining the skin color. Melanogenesis is catalyzed by tyrosinase (TYR), tyrosinase-related protein 1 (TYRP1), and dopachrome tautomerase (DCT). Therefore, these enzymes are suitable targets for the development of cosmetics aimed at skin whitening. In this study, we investigated the effect of milk whey on melanin production. Whey obtained from five strains of lactic acid bacteria (L. delbrueckii bulgaricus, L. helveticus, L. acidphillus, L. casei, and L. helveticus CM4 strains) was used. The melanin contents in B16 melanoma cells treated with α-MSH was significantly increased by about 2-fold compared to control cells. In contrast, melanin production by α-MSH was significantly suppressed in whey obtained from any lactic acid bacteria. These wheys inhibited α-MSH-induced increased expression of TYR, TYRP1, and DCT. When the whey obtained from L. helveticus was examined in detail, it was found that the fraction with a molecular weight of 3 kDa or more had a strong melanin production inhibitory effect. These results demonstrated that whey decreases the expression of TYR, TYRP1, and DCT and suppresses melanin production. It was also suggested that substances with a molecular weight of 3 kDa or more may be involved in this action of whey.