Tyrosinase (Tyr) catalyzes hydroquinone (HQ) oxidation via two main pathways. The HBQ pathway directly oxidizes HQ to 2-hydroxy-1,4-benzoquinone (HBQ), which dimerizes and forms hydroquinone-eumelanin (HQ-EM). The BQ pathway involves dopaquinone (DQ)-mediated redox exchange producing p-benzoquinone (BQ), which reacts with cysteine (Cys) to form 2-S-cysteinylhydroquinone (Cys-HQ) and further oxidizes to hydroquinone-pheomelanin (HQ-PM). These pathways illustrate the enzymatic