Cytotoxicity of GAE in B16F10 cells was measured
using the MTT assay. When B16F10 cells were treated
with 0-50 μg/mL GAE no significant cytotoxic effect was
evident (Fig. 3d). Melanin levels and melanin pigmentation induced by α-MSH were reduced in a concentrationdependent manner by GAE treatment (Fig. 3e-f ). To test
whether GAE inhibited tyrosinase, a key enzyme catalyzing the rate-limiting step in melanin biosynthesis,
tyrosinase zymography and tyrosinase luciferase reporter
activation assays of enzyme activity were carried out in
B16F10 melanoma cells. Tyrosinase activity in GAE treated and cultured B16F10 melanoma cells was
suppressed in a dose-dependent pattern (Fig. 3g-i).