The effect of KZE on mushroom tyrosinase activity. Mushroom tyrosinase activity was determined by L-DOPA oxidation in a cell-free system. Stimulation of tyrosinase activity in vitro by KZE at 0.3125-5 mg/ml. MOP being positive controls at 500 μ M. Results shown are means ± SEM and are representative of three independent experiments. Data were analyzed by One-Way Analysis of Variance (ANOVA) followed by post hoc Tukey test. **P < 0.01, compared with control.