Effect of 2,3,4-Trihydroxyacetophenone (2,3,4-Thap) and 2,4,5-Trihydroxybutyrophenone (2,4,5-Thbp) on the Rate of Dl-Dopa Oxidation by Mushroom Tyrosinase

Abstract

Various concentrations of 2,3,4‐trihydroxyacetophenone (2,3,4‐THAP) and 2,4,5‐trihydroxybutyrophenone (2,4,5‐THBP) have a synergistic effect on the rate of DL‐3,4‐dihydroxyphenylalanine (DL‐DOPA) oxidation by mushroom tyrosinase as measured by absorbance at 475 nm. The synergism results from the ability of dopaquinone to nonenzymatically oxidize 2,3,4‐THAP and 2,4,5‐THBP to the corresponding o‐quinone. Moreover, various concentrations of 2,3,4‐THAP and 2,4,5‐THBP prevent the enzymatic conversion of DL‐DOPA to DOPA‐melanin, probably due to the ability of these trihydroxyphenols to interact nonenzymatically with dopaquinone.