A new type of tyrosinase inhibitors from natural products as potential treatments for hyperpigmentation.

Selected flavonoids were evaluated for their effects on melanin biosynthesis by using mushroom-tyrosinase assay. Out of 27 tested flavonoids, only six showed a potential inhibitory activity on melanin biosynthesis. Flavonoids containing an alpha-keto group showed to be the active compounds in this assay. This may be explained in terms of similarity between the dihydroxyphenyl group in L-DOPA and the alpha-ketol group in flavonoids. The results of this study revealed a new type of tyrosinase inhibitor from natural origin. These compounds will be further examined for their application for treatment of hyperpigmentation problems e.g. melasma and ephelides.