Halogenated aromatic thiosemicarbazones as potent inhibitors of tyrosinase and melanogenesis.

A set of 21 halogenated thiosemicarbazones (TSCs) have been synthesized and its inhibitory properties toward activity diphenolase of mushroom tyrosinase and their ability to inhibition of melanogenesis in B16F10 murine, melanoma cell line have been investigated. The molecular docking to the active site of the enzyme has been also performed to investigate the nature of enzyme-inhibitor interactions. The obtained outcomes allowed us to perform SAR analysis. TSC 6, 12 and 21 exhibited the most potent inhibitory properties showing IC of 0.5, 0.9 and 0.8 µM, respectively. They revealed reversible and competitive manner of tyrosinase inhibition. According to SAR analysis, para-substituted acetophenone derivatives of thiosemicarbazones have the highest affinity to the enzyme among the investigated compounds. Melanin production in B16F10 cells was inhibited by all investigated compounds at the micromolar level. Suggested inhibition mechanism is based on the interaction between a sulfur atom of thiourea moiety of the thiosemicarbazones, and copper ions in the active site of the enzyme. These results might be useful in searching novel inhibitors of melanogenesis which could be used in the cosmetic and food industry.