Rational design of triazole tyrosinase inhibitors via integrated free energy calculations

Tyrosinase (TYR) is a copper-containing metalloenzyme involved in melanin biosynthesis and is an important target in the development of treatments for hyperpigmentation disorders, including melasma, post-inflammatory hyperpigmentation, and melanoma. Among the scaffold classes investigated for TYR inhibition, 1,2,4-triazole derivatives have attracted increasing interest. In this study, we evaluated a structurally diverse series of triazole derivatives using an integrated computational workflow that included absorption, distribution, metabolism, excretion and toxicity (ADMET) profiling, molecular docking, molecular dynamics (MD) simulations, and binding free energy calculations based on Linear Interaction Energy (LIE) and Free Energy Perturbation (FEP). Using Bacillus megaterium TYR as the model enzyme, the triazole derivatives generally produced more favorable docking scores than kojic acid and established recurring interactions with hydrophobic residues such as Met215, Val217, Ala221, and Phe227, as well as hydrogen-bonding contacts with Gly216. The free energy calculations reproduced the experimental binding affinities with high accuracy (FEP: R² = 0.91, MAE = 0.20 kcal/mol; LIE: R² = 0.93, MAE = 0.54 kcal/mol). Residue-level energy analysis indicated that interactions involving Arg209, Gly216 and Val218 play a major role in ligand binding across the series, with aromatic and halogenated substituents favoring stronger van der Waals contacts in this region. Overall, these results provide a consistent structural and energetic framework for understanding triazole-based TYR inhibition and may support the rational design of improved inhibitors for cosmetic and therapeutic applications.