Arbutin

Overview
Arbutin is both an ester and a glycoside; a glycosylated benzoquinone extracted from bearberry plant in the genus Arctostaphylos. It inhibits tyrosinase and thus prevents the formation of melanin. Arbutin is therefore used as a skin-lightening agent. Arbutin is also found in wheat, and is concentrated in pear skins.

Risks
Arbutin is glucosylated hydroquinone, and may carry similar cancer risks, although there are also claims that arbutin reduces cancer risk. The German Institute of Food Research in Potsdam found that intestinal bacteria can transform arbutin into hydroquinone, which creates an environment favourable for intestinal cancer. It is known that the body excretes 64-75% of arbutin in urine, and arbutin converted to hydroquinone has an antibacterial effect in the urinary tract, hence the use of bearberry in herbal medicine, but it is not known why this substance plays a role in cancer development.