Synthesis of Resorcinol Derivatives and their Effects on Melanin Production

Several resorcinol derivatives were synthesized and their effects on the survival rate of B16 murine melanoma cells, melanin production, and tyrosinase activity were investigated with an aim to evaluate their skin whitening effect. Twelve resorcinol derivatives were synthesized by esterification with three functional groups (L-ascorb-6-yl, ethyl, and glyceryl) linked via four alkyl chains of varying lengths (n = 2–5) at the 4-position. The structures of the 12 resorcinol derivatives were confirmed by Nuclear Magnetic Resonance (NMR). The derivatives were added to B16 murine melanoma cells and the melanin contents in the cells and culture medium were measured. To measure the tyrosinase activity, the substrate L-DOPA was added to a mushroom-derived tyrosinase solution, and the inhibition of the tyrosinase activity was determined. At 10 µM, the resorcinol derivatives did not affect the survival of the B16 murine melanoma cells, but the melanin content was reduced. At 1 µM, the derivatives significantly inhibited the tyrosinase activity in the mushroom-derived tyrosinase solution. A plot of the inhibitory effect on melanin production against the cLogP value for each resorcinol derivative indicated that the highest inhibition occurred at a cLogP value of approximately 2. Therefore, these resorcinol derivatives are expected to serve as effective skin whitening agents.