4.4. Tyrosinase Inhibition Assay

The mushroom tyrosinase inhibitory activity of OISEA was determined by spectrophotometry as described previously, with minor modifications [29]. The reaction mixture containing 100 μL of 0.1 M phosphate buffer (pH 6.5) with or without sample, 50 μL of 1 mM l-tyrosine, and 50 μL of mushroom tyrosinase (200 units/mL) was added into a 96-well microplate (SPL, Pocheon, Korea). The linear increase in OD₄₉₀ was measured at room temperature.