Effect of Maltol on the Oxidation of DL-DOPA,Dopamine, N-Acetyldopamine (NADA), and Norepinephrine by Mushroom Tyrosinase

Maltol (3-hydroxy-2-methyl-4H-pyran-4-one) appears to inhibit the rate of oxidation of DL-DOPA, dopamine, NADA and epinephrine by tyrosinase when assayed spectropho-tometrically but not when assayed polarographically. Maltol has an effect on the spectrum of product(s) formed when each catecholamine was oxidized by tyrosinase showing that maltol hastens the disappearance of the quinones, possibly by conjugating with them. Indeed, at relatively high concentrations, maltol prevented the conversion of DL-DOPA, dopamine, and norepinephrine to their corresponding melanins via tyrosinase.