EFFECT OF KOJIC ACID ON THE OXIDATION OF DL-DOPA, NOREPINEPHRINE, ANDDOPAMINE BY MUSHROOM TYROSINASE

Kojic acid inhibits effectively the rate of formation of pigmented pro duct(s) and of oxygen uptake when DL-DOPA, norepinephrine and dopamine are oxidized by mushroom tyrosinase. In addition to the direct effect of kojic acid on the enzyme, kojic acid also affects the UV-VIS spect rum of the final product(s) formed, this being due to the ability of t he o-quinones of these substrates to oxidize kojic acid to a yellow pr oduct(s). Kojic acid can thus prevent the conversion of the o-quinones of DL-DOPA, norepinephrine and dopamine to their corresponding melani n.