Natural Mimetic 4,6-Dihydroxyaurone Derivatives as Tyrosinase Inhibitors: Design, Synthesis, and Biological...

Tyrosinase, a key enzyme in melanin biosynthesis and food browning, has become an important target for inhibitor development. This study aimed to investigate the inhibitory potential of 4,6-dihydroxyaurone derivatives with varied ring B substituents on mushroom tyrosinase.

A set of 4,6-dihydroxyaurone derivatives, each with varied substituent patterns on ring B, were designed and subjected to computational studies to predict their binding affinity, binding modes with tyrosinase, and drug-likeness properties. These aurone derivatives were subsequently synthesized and evaluated in vitro for their tyrosinase inhibitory activity. Enzyme kinetics studies were conducted to determine the mode of tyrosinase inhibition.

Computational studies of the twenty designed aurone derivatives indicated their strong binding within the active site and exhibited favorable drug-likeness properties. In vitro UV-Vis spectrophotometric assays of the synthesized compounds revealed that compound 5h, featuring a 3,4-dichlorophenyl substituent on ring B, showed the most potent tyrosinase inhibitory activity (IC₅₀ = 6.3 ± 0.3 μM) compared to kojic acid (IC₅₀ = 136.5 ± 11.5 μM). Kinetic studies and molecular docking simulations indicated that compound 5h inhibits tyrosinase through a mixedtype inhibition mechanism, with competitive and uncompetitive inhibition constants of 21 μM and 68 μM, respectively.

These findings highlight the promising potential of 4,6-dihydroxyaurone derivatives as potent tyrosinase inhibitors for applications in pharmaceuticals, cosmetics, and agriculture.