Inhibitory effect of water-soluble extract from wheat germ on melanin formation

摘要

Melanin has an important role in photoprotection of skin. Melanins are classified into two major categories; black eumelanin and yellow to reddish-brown pheomelanin. Production of eumelanin in melanocytes is enhanced by UVB stimulation. Since aim of whitening-cosmetics is to suppress an excess production of melanin, specific inhibition of eumelanin can be one of novel whitening methods. In this study, we examined inhibitory effect of water-soluble extract from wheat germ on melanin formation. The extract remarkably lightened color of melanocytes and reduced eumelanin content, while change in pheomelanin content was not observed. The significant reduction of size of spots was observed after topical application of the extract for 56 days. The extract affected neither tyrosinase activity nor gene expression of tyrosinase, TRP-1 and TRP-2. Thiol-related compounds didn't seem to be an essential component in the extract. These results indicate that water-soluble extract from wheat germ may be a new type of whitening agent specific for inhibiting eumelanin.