2.3.1. Tyrosinase (TYR) Inhibition

Tyrosinase inhibitory activity of urolithin A was evaluated using 96-well plates and l-DOPA as the substrate [21]. The α-Kojic acid was used as a reference inhibitor. The reaction mixture contained 10 μL of urolithin A at different concentrations in DMSO, 80 μL phosphate buffer (pH = 6.8), 40 μL of l-DOPA, and 40 μL of tyrosinase (200 U/mL) in each well. Controls wells contained 10 μL of DMSO in place of the sample. The absorbance was measured at 475 nm (endpoint) using a Synergy H1 Hybrid Multi-Mode Reader (Biotek, Bad Friedrichshall, Germany). Inhibitory activity was determined as: % Inhibition = (Absorbance Control − Absorbance Urolitihin A)/(Absorbance Control) × 100
