Antimelanogenic potential of brewer's spent grain extract through modulation of the MAPK/MITF axis

Beer brewing produces >39 million tons of brewer's spent grain (BSG) per year worldwide. Although BSG is rich in protein, fiber, and phytochemicals, it is mainly used as livestock feed, and some is discarded. In this study, we attempted to assess the antimelanogenesis effects of BSG and identify the functional components. To this end, we investigated the antioxidant and antimelanin synthesis effects of a BSG extract (BSGE). The results showed that BSGE has high DPPH radical-scavenging activity and inhibited alpha-MSH-induced melanin synthesis in B16F10 cells cultured in both 2D and 3D environments. BSGE also reduced the expression levels of MITF, TRP-1, TRP-2, and tyrosinase in B16F10 cells by regulating the MAPK pathway. We confirmed the skin-whitening effect of BSGE in 3D reconstituted human skin and zebrafish embryo models. HPLC analysis showed that BSGE contains ferulic acid and p-coumaric acid, which are known to have whitening effects. Thus, BSGE can be used in multifunctional cosmetics as a sustainable ingredient with antioxidant and skin-whitening properties.