Discovery of Novel Dihydroxyphenol Tyrosinase Inhibitors for Treatment of Pigmentation: From Enzyme Screening to Three-Dimensional Human Skin Melanin Evaluation

Tyrosinase inhibitors constitute a class of pharmacological agents with broad applications in both therapeutic and cosmetic formulations, owing to the modulation of skin pigmentation. However, the clinical development of these agents has been hampered by suboptimal efficacy profiles and safety considerations. In the present study, we employed a rational pharmacophore hybridization approach to design novel tyrosinase inhibitors. Systematic evaluation of the synthesized compounds revealed potent tyrosinase inhibition, with the majority exhibiting nanomolar-range IC₅₀ values, representing a significant improvement over kojic acid and arbutin. The optimal compound III19 demonstrated exceptional performance across multiple validation models, including melanin production assays and zebrafish antipigmentation evaluation, and maintained robust efficacy in a reconstructed 3D melanocytic human skin test. Furthermore, preliminary cytotoxicity, skin permeability, and metabolic stability evaluation of compound III19 was also conducted. These results advanced the understanding of structure-activity relationships in phenolic tyrosinase inhibitors and provided promising leads for discovering novel antipigmentation agents.