Enzymatic synthesis of arbutin undecylenic acid ester and its inhibitory effect on mushroom tyrosinase

A novel tyrosinase inhibitor, an arbutin derivative having undecylenic acid at the 6-position of its glucose moiety, was enzymatically synthesized. Its inhibitory activity was studied in vitro by using catechol and phenol as substrates. The IC₅₀ value of the arbutin ester on tyrosinase using catechol (4 × 10⁻⁴ M) was 1% of that when arbutin (4 × 10⁻² M) was used. Using phenol, IC₅₀ of the arbutin ester (3 × 10⁻⁴ M) as substrate was 10% of that of arbutin (3 × 10⁻³ M). These results suggest that the arbutin ester inhibits the latter part of the tyrosinase reaction, which consists of hydroxylation and oxidation.