A series of 4-functionalized phenyl-O-beta-D-glycosides were designed, synthesized and evaluated as a new class of mushroom tyrosinase inhibitors. The results demonstrated that compounds 6a-13a bearing a thiosemicarbazide moiety exhibited potent activities with IC50 values range from 0.31 to 52.8 microM. Particularly, compound 9a containing acetylated glucose moiety was found to be the most active molecule with an IC50 value of 0.31 microM. SARs analysis suggested that (1) the thiosemicarbazide moiety remarkably contributed to the increase of inhibitory effects on tyrosinase; (2) the configuration and bond type of sugar moiety also played a very important role in determining their inhibitory activities. The inhibition kinetics and inhibition mechanism study revealed that compound 9a was reversible and competitive type inhibitor, whereas compound 13a was reversible and competitive-uncompetitive mixed-II type inhibitor.