Inhibitory Effects of Flavonoid Glycosides Isolated from the Peel of Japanese Persimmon (Diospyros kaki 'Fuyu') on Melanin Biosynthesis

We found that the acetone extract of the peel of Japanese persimmon (Diospyros kaki 'Fuyu') inhibits melanin biosynthesis in mouse B16 melanoma cells. The activity-guided purification of the extract resulted in isolation of two active compounds, which have been identified as flavonoid glycosides, isoquercitrin (quercetin-3-O-glucoside) and hyperin (quercetin-3-O-galactoside) by spectral analysis. Isoquercitrin and hyperin strongly inhibited the production of melanin (IC50: 21.7 and 18.2 mu M, respectively). The inhibitory effects were found to be mediated by suppression of tyrosinase expression.