Inhibitory effects of arbutin-β-glycosides synthesized from enzymatic transglycosylation for melanogenesis

To develop a new skin whitening agent, arbutin-beta-glycosides were synthesized and evaluated for their melanogenesis inhibitory activities. Three active compounds were synthesized via the transglycosylation reaction of Thermotoga neapolitana beta-glucosidase and purified by recycling preparative HPLC. As compared with arbutin (IC50 = 6 mM), the IC50 values of these compounds were 8, 10, and 5 mM for beta-D-glucopyranosyl-(1 -> 6)-arbutin, beta-D-(1 -> 4)-arbutin, and beta-D-glucopyranosyl-(1 -> 3)-arbutin, respectively. beta-D-Glucosyl-(1 -> 3)-arbutin also exerted the most profound inhibitory effects on melanin synthesis in B16F10 melanoma cells. Melanin synthesis was inhibited to a significant degree at 5 mM, at which concentration the melanin content was reduced to below 70% of that observed in the untreated cells. Consequently, beta-D-glucopyranosyl-(1 -> 3)-arbutin is a more effective depigmentation agent and is also less cytotoxic than the known melanogenesis inhibitor, arbutin.