Figure 3.

(A) Dose-dependent curves of mushroom tyrosinase inhibition exerted by kojic acid as a positive control (dashed line) and by PEE (continuous line). Tyrosinase activity was determined in a cell-free, in vitro assay using l-tyrosine as a substrate. Data are mean percent inhibitions ± SD from six replicates in two independent experiments (see Materials and Methods). (B) Inhibition of melanin production in MeWo melanoma cells after 72 h incubation with 1 mg/mL arbutin, or with 50 µg/mL PEE. Cell melanin production was quantified as mean 505 nm absorbances ± SD from three replicates in two independent experiments. * = p < 0.01 with respect to the control.