Effect of benzenesulfinic acid on the oxidation of o-dihydroxy and trihydroxyphenols by mushroom tyrosinase

Benzenesulfinic acid inhibits the rate of oxidation of different o-dihydrox yphenols and trihydroxyphenols by tyrosinase when assayed spectrophotometri cally but barely has an effect when assayed polarographically. Benzenesulfi nic acid is a much more effective inhibitor of the rate of oxidation to pig mented product(s) by tyrosinase of o-dihydroxyphenols than of trihydroxyphe nols. The spectrum of the final product(s) formed by the oxidation of most of the tested substrates was different in the absence versus presence of be nzenesulfinic acid suggesting that the latter traps the o-quinones forming phenylsulfonyl derivatives in the reaction.