Discrimination between Alternative Substrates and Inhibitors of Tyrosinase

Many phenolic compounds have been described in the scientific literature as inhibitors of tyrosinase. In this work a test is proposed that allows us to distinguish whether a molecule is an enzyme inhibitor or substrate. The test has several stages. First, the degree of inhibition of the studied molecule is determined on the monophenolase activity (i_M) and on the diphenolase activity (i_D). If i_M = i_D, it is an inhibitor. If i_M ≠ i_D, the molecule could be substrate or inhibitor. Several additional stages are proposed to solve this ambiguity. The study described herein was carried out using the following molecules: benzoic acid, cinnamic acid, guaiacol, isoeugenol, carvacrol, 4-tert-butylphenol, eugenol, and arbutin.