Acetazolamide Inhibits the Level of Tyrosinase and Melanin: An Enzyme Kinetic, In Vitro, In Vivo, and In Silico Studies

Melanin is the major factor that determines skin color and protects from ultraviolet radiation. In present study we evaluated the anti-melanogenesis effect of acetazolamide (ACZ) using four different approaches: enzyme kinetic, in vitro, in vivo and in silico. ACZ demonstrated significant inhibitory activity (IC50 7.895 +/- 0.24 mu M) against tyrosinase as compared to the standard drug kojic acid (IC50 16.84 +/- 0.64 mu M) and kinetic analyses showed that ACZ is a noncompetitive inhibitor without cytotoxic effect. In in vitro experiments, A375 human melanoma cells were treated with 20 or 40 mu M of ACZ with or without 50 mu M of (L)-DOPA. Western blot results showed that ACZ significantly (P < 0.05) decreased the expression level of tyrosinase at 40 mu M. Zebrafish embryos were treated with 10, 20 or 40 mu M of ACZ and of positive control kojic acid. At 72 h of treatment with ACZ and kojic acid, ACZ significantly (P < 0.001) decreased the embryos pigmentation to 40.8% of untreated embryos at the dose of 40 mu M of ACZ while kojic acid decreased only 25.0% of pigmentation at the same dose of kojic acid. In silico docking were performed against tyrosinase using PyRx tool. Docking studies suggested that His244, Asn260 and His85 are the major interacting residues in the binding site of the protein. In conclusion, our results suggest that ACZ is a good candidate for the inhibition of melanin and it could be used as a lead for developing the drugs for hyperpigmentary disorders and skin whitening.