Effects of wogonin on the mechanism of melanin synthesis in A375 cells

The present study aimed to investigate the effect of wogonin on the mechanism of melanin synthesis in the A375 melanoma cell line. A375 cells, cultured in vitro, were treated with wogonin and the activity of tyrosinase (TYR) and melanin synthesis were examined via MTT assay, L-dopa oxidation assay and an NaOH lysis assay. Protein expression levels of TYR and c-Jun N-terminal kinase (JNK) were examined via western blotting. mRNA expression levels of TYR, tyrosinase related protein (TRP)-1, TRP-2, extracellular signal-regulated kinase (ERK)-1, ERK-2 and JNK-2 were analyzed by reverse transcription-quantitative polymerase chain reaction. Furthermore, the effect of wogonin on estrogen receptor inhibitor (ICI182780) and ERK pathway inhibitor (U0126) was investigated. Safe doses of wogonin (10, 1, 10^-1, 10^-2 or 10^-3 µmol/l) significantly inhibited melanin synthesis and TYR activity (P<0.05). Wogonin (10 µmol/l) inhibited the protein expression levels of TYR, JNK and mRNA expression levels of TYR, TRP-1, TRP-2, ERK-1, ERK-2, JNK-2 in A375 cells (P<0.01). The estrogen receptor inhibitor, ICI182780, and MEK inhibitor, U0126, significantly reversed the effects of wogonin on protein and mRNA expression levels of TYR, TRP-1, TRP-2, ERK-1, ERK-2 and JNK-2 (all P<0.01). To conclude, the present study identified that wogonin is able to inhibit the synthesis of melanin in A375 cells, through inhibiting protein and mRNA expression levels of TYR, TRP-1, and TRP-2, and ERK1, ERK2 and JNK2, respectively.