The mushroom tyrosinase was used fo

The mushroom tyrosinase was used for the bioassay. The inhibition on tyrosinase-catalyzed oxidation of L-DOPA was determined as previously described (Kubo et al., 2000). The reaction mixture contained samples, phosphate buffer (0.8 ml, 25 mM, pH 6.8) and L-DOPA (final 3.8 mM) then mushroom tyrosinase (0.1 ml, final 250 units/ml) was added into the mixture to measure the initial rate as a linear increase in the absorbance at 475 nm for 5 min. The reaction was performed at 25 oC. The value in the absence sample was represented as the control.