Syntheses of α-arbutin-α-glycosides and their inhibitory effects on human tyrosinase

α-Arbutin is a tyrosinase inhibitor. We synthesized α-arbutin-α-glycosides by the transglycosylation reaction of cyclomaltodextrin glucanotransferase from Bacillus macerans using α-arbutin and starch as acceptor and donor molecules, respectively. We isolated and characterized two major products from the reaction mixture. The structural analyses using 13C- and 1H-NMR spectroscopy proved that they were 4-hydroxyphenyl α-maltoside (α-Ab-α-G1) and 4-hydroxyphenyl α-maltotrioside (α-Ab-α-G2). Both α-Ab-α-G1 and α-Ab-α-G2 exhibited competitive-type inhibition on human tyrosinase as α-arbutin does. Their Ki values were calculated to be 0.6 mM and 2.8 mM, respectively, which is slightly and significantly higher than that of α-arbutin (0.2 mM).