Mushroom Tyrosinase Activity

In vitro tyrosinase inhibitory activity assay was determined using the method described previously with slight modifications [16, 17]. In briefly, each 5 μl of purified mushroom tyrosinase (Sigma, 2 × 10³ units/ml) and 5 μl of the test samples (0, 1, 5 μM) was adjusted with 0.1 M potassium phosphate buffer (PH 6.8) for total volume of 100 μl. After mixing by gentle shaking at 25°C for 10 min, 50 μl of L-tyrosine solution (0.3 mg/ml) was added to a 96 well plate. The plate was incubated at 25 °C for a few min, and then the absorbance was measured at 475 nm using a microplate reader (Sunrise-Basic Tecan, Tecan Austria GmbH 5082 Groding, Austria). The tyrosinase activity was calculated as a percentage to untreated control.