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

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