Punicalagin as a novel tyrosinase and melanin inhibitor: Inhibitory activity and mechanism.

The inhibition of punicalagin on tyrosinase and melanogenesis was investigated through multiple spectroscopic approaches, molecular docking, molecular dynamic simulation, cell assay, and preservation assays. The results confirmed that punicalagin significantly inhibited tyrosinase activity in vitro (IC₅₀ = 0.64 ± 0.05mM) and B16F10 cells (IC₅₀ = 16 ± 0.7μM). The binding of punicalagin to tyrosinase changed the conformation of the enzyme by influencing the hydrophobicity and polar environment of the binding site. The results of molecular docking and thermodynamic analysis showed that hydrophobic interaction and hydrogen bond were major driving forces in stabilizing the punicalagin-tyrosinase complex, influencing substrate-binding affinity to tyrosinase and resulting in tyrosinase activity reduction. Molecular dynamic analysis indicated that punicalagin stretched the basic framework structure of tyrosinase and lowered the surface hydrophobicity of the enzyme. Cell analyses further demonstrated that punicalagin inhibited melanogenesis by down-regulating the expressions of MITF and tyrosinase. What's more, preservation...