arbutine

Arbutin, commonly spelled arbutin, is a glycoside of hydroquinone. Chemically it is hydroquinone O-beta-D-glucopyranoside and occurs mainly as the beta anomer in nature, with the alpha form (alpha-arbutin) also known, typically produced synthetically or isolated in certain plants. It is found in several plants, most notably bearberry (Arctostaphylos uva-ursi) leaves, and can be extracted from other members of the Ericaceae family.

Mechanism: Arbutin acts as a tyrosinase inhibitor, reducing melanin synthesis in melanocytes. It is generally considered to be a reversible inhibitor. In vivo, arbutin can be hydrolyzed by β-glucosidases to yield hydroquinone and glucose, a pathway that contributes to both its pigment-lightening activity and potential safety considerations.

Applications: In cosmetics, arbutin is used as a skin-lightening agent to treat hyperpigmentation, age spots, and uneven complexion. Formulations typically use low to moderate concentrations, and products may combine arbutin with other active ingredients. It has been researched as a gentler alternative to hydroquinone, though hydroquinone can still be released under certain conditions.

Safety and regulation: Adverse effects include skin irritation and rare allergic reactions. Because hydroquinone release is possible, regulatory oversight varies by jurisdiction. Some authorities restrict concentrations or approve arbutin-containing products with caveats, while others require caution or ban hydroquinone release. Users should follow product labeling and use sun protection to minimize photo-induced pigmentation changes.