Inhibition effects and binding interactions of epigallocatechin and gallocatechin on tyrosinase and their anti-melanogenesis activity.

Tyrosinase is a key enzyme in melanogenesis and food enzymatic browning. This study systematically investigated tyrosinase inhibition effects and binding interactions of two tea catechins epigallocatechin (EGC) and gallocatechin (GC), and their practical efficacy. In vitro enzymatic assays showed that EGC and GC both reversibly inhibited tyrosinase in a mixed-type manner, with IC50 values of 0.059 ± 0.002 mg/ml (192.02 ± 7.19 µM) and 0.036 ± 0.001 mg/ml (118.77 ± 4.11 µM), respectively. Fluorescence quenching, synchronous fluorescence, CD spectra, ANS-binding assay, and molecular docking results revealed the binding between EGC or GC and tyrosinase, changed enzyme conformation and microenvironment, subsequently leading to a decrease in enzyme activity. Cellular studies demonstrated that EGC and GC obviously inhibited intracellular tyrosinase activity and melanin synthesis in B16 melanoma cells. These findings provide comprehensive mechanistic insights into the anti-tyrosinase activity of EGC and GC and support their potential application as natural inhibitors.