Effect of kojic acid on the hydroxylation of L-tyrosine and tyramine by mushroom tyrosinase

Kojic acid inhibits effectively the rate of L-tyrosine and tyramine hydroxy lation by mushroom tyrosinase. It also affects the spectrum of product(s) f ormed, this being due to the ability of dopaquinone and dopamine-(o) under bar-quinone to oxidize kojic acid to a yellow product(s). Kojic acid preven ts the conversion of these (o) under bar-quinones to their corresponding me lanins. An insoluble yellow product(s) is formed when tyramine, but not L-t yrosine, is incubated with tyrosinase for 20 h in the presence of excess ko jic acid.