Integrating Computational Modeling and Experimental Validation to Unveil Tyrosinase Inhibition Mechanisms of Flavonoids from <i>Alhagi graecorum</i>

Flavonoids, natural compounds ubiquitous in the human diet, are esteemed for their multifaceted pharmacological properties. The tyrosinase inhibitory capacity of five flavonoids from <i>Alhagi graecorum</i> was investigated through a comprehensive integration of <i>in vitro</i> and <i>in silico</i> methodologies. Molecular docking simulations demonstrated the proficient binding of the isolated compounds to the principal binding site of tyrosinase, akin to the standard tyrosinase inhibitor kojic acid. These compounds exhibited analogous binding affinities, among which compound <b>5</b> manifested notably heightened levels of polar bonds and hydrophobic interactions. Molecular dynamics (MD) simulations were utilized to explore the interaction dynamics between the isolated flavonoids and tyrosinase. The analysis of various MD parameters revealed consistent trajectories for the tested compounds, with compound <b>5</b> demonstrating notable energy equilibration. Strong hydrogen bonding interactions were observed between the flavonoids and the tyrosinase active site. The results of interaction energy calculations showed a balanced interaction mediated by hydrophobic interactions, with compound <b>5</b> exhibiting the lowest interaction energies. Additionally, the findings from MM/PBSA analysis demonstrated the lowest binding free energy for compound <b>5</b>. Moreover, the <i>in vitro</i> tyrosinase inhibition assay revealed notable discrepancies among the studied flavonoids. Particularly, compound <b>5</b> demonstrated the most pronounced anti-tyrosinase activity, as evidenced by its lowest IC₅₀ value. This experimental outcome is consistent with the results of computational predictions. Therefore, flavonoids of <i>A. graecorum</i> might be valuable for the development of tyrosinase inhibitors.