Abstract
This study aimed to assess apple blossom extracts as potential natural whitening agents due to their ability to inhibit melanogenesis. Ethanol extracts of apple blossom (ABE) were assessed for biological activity in the B16F10 mouse melanoma cell line. ABE toxicity was assessed by thiazolyl blue tetrazolium bromide (MTT) assay. Levels of melanogenic enzyme expression in response to ABE supplementation were assessed by western blotting. Also assessed purified kaempferol, one of the phenolic compounds extracted from apple blossom, was evaluated using western blot analysis. The expression levels of cellular tyrosinase, microphthalmia-associated transcription factor (MITF), tyrosinase-related protein (TRP)-1, and TRP-2 proteins related to melanogenesis decreased in a dose-dependent manner with ABE treatment of cells. Using nuclear magnetic resonance, we identified kaempferol in the ABE. Treatment of cells with purified kaempferol decreased the expression levels of tyrosinase and the MITF protein to a similar degree as that observed with ABE treatment. This suggests that the efficacy of melanogenesis-related inhibition demonstrated by ABE was due to kaempferol. ABE has an inhibitive effect on melanogenic enzymes and potentially can be applied to functional foods and cosmetics having a whitening effect as a natural material.