Structural criteria for depigmenting mechanism of arbutin

Arbutin, hydroquinone‐ O ‐ β ‐ d ‐glucopyranoside (1) was found to inhibit the oxidation of l ‐tyrosine (monophenolase activity) catalyzed by mushroom tyrosinase. However, arbutin itself was oxidized as a monophenol substrate at an extremely slow rate, and this oxidation was accelerated as soon as catalytic amounts (0.01 m m ) of l ‐3,4‐dihydroxyphenylalanine ( l ‐DOPA) became available as a cofactor. The result observed was supported by monitoring oxygen consumption. The depigmenting mechanism of arbutin previously reported is supportable if a cofactor is not available in the melanocytes. The combination with l ‐ascorbic acid is a useful application, particularly when oxygen is limited. Copyright © 2004 John Wiley & Sons, Ltd.