Tyrosinase Inhibitory Activity

The tyrosinase inhibitory activity of HI extract was calculated using a slightly modified previously described method [26]. In a 96-well plate, four wells were designated (HI lyophilized extract dissolved in water containing 5% DMSO) as follows: (A) 46 U/mL (40 μL) mushroom tyrosinase (MT) in 66 mM phosphate buffer (PB), pH 6.6 (120 μL); (B) only PB (160 μL); (C) PB (80 μL), MT (40 μL) and the sample (40 μL); (D) PB (120 μL) and the sample (40 μL). After incubation at room temperature for 10 min, 2.5 mM L-DOPA prepared in PB (40 μL) was added in all wells. After room temperature incubation for 20 min, the absorbance was measured at 475 nm. The tyrosinase inhibitory activity was calculated using kojic acid as an external standard (0.01–0.10 mg/mL). The inhibition percentage of enzymatic

activity was assessed by the following equation: [(A − B) − (C − D)] × 100/(A − B). The results were expressed as milligram kojic acid equivalents (KAE) per dw extract (mg KAE/g dw).
