Arbutin is both an ether

Ether

Ethers are a class of organic compounds that contain an ether group — an oxygen atom connected to two alkyl or aryl groups — of general formula R–O–R'. A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether"...

 and a glycoside

Glycoside

In chemistry, a glycoside is a molecule in which a sugar is bound to a non-carbohydrate moiety, usually a small organic molecule. Glycosides play numerous important roles in living organisms. Many plants store chemicals in the form of inactive glycosides. These can be activated by enzyme...

; a glycosylated hydroquinone

Hydroquinone

Hydroquinone, also benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, having the chemical formula C6H42. Its chemical structure, shown in the table at right, has two hydroxyl groups bonded to a benzene ring in a para position. It is a white granular solid...

 extracted from bearberry

Bearberry

Bearberries are three species of dwarf shrubs in the genus Arctostaphylos. Unlike the other species of Arctostaphylos , they are adapted to Arctic and sub-Arctic climates, and have a circumpolar distribution in northern North America, Asia and Europe, one with a small highly disjunctive population...

 plant in the genus Arctostaphylos. It inhibits

Enzyme inhibitor

An enzyme inhibitor is a molecule that binds to enzymes and decreases their activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. They are also used as herbicides and pesticides...

 tyrosinase

Tyrosinase

Tyrosinase also known as monophenol monooxygenase is an enzyme that catalyses the oxidation of phenols and is widespread in plants and animals...

 and thus prevents the formation of melanin

Melanin

Melanin is a pigment that is ubiquitous in nature, being found in most organisms . In animals melanin pigments are derivatives of the amino acid tyrosine. The most common form of biological melanin is eumelanin, a brown-black polymer of dihydroxyindole carboxylic acids, and their reduced forms...

. Arbutin is therefore used as a skin-lightening agent. Arbutin is found in wheat

Wheat

Wheat is a cereal grain, originally from the Levant region of the Near East, but now cultivated worldwide. In 2007 world production of wheat was 607 million tons, making it the third most-produced cereal after maize and rice...

, and is concentrated in pear

Pear

The pear is any of several tree species of genus Pyrus and also the name of the pomaceous fruit of these trees. Several species of pear are valued by humans for their edible fruit, but the fruit of other species is small, hard, and astringent....

 skins. It is also found in Bergenia crassifolia

Bergenia crassifolia

Bergenia crassifolia, the badan, Siberian tea, Mongolian tea, leather bergenia, winter-blooming bergenia, heartleaf bergenia, elephant's ears or elephant-ears, is a plant species in the genus Bergenia. It is about 12 inches tall. The leaves are spoon-shaped. One cultivar is Bergenia...

.

Skin lightening agent

Bearberry extract is used in skin lightening treatments designed for long term and regular use. An active agent in brands of skin lightening preparations, it is more expensive than traditional skin lightening ingredients like hydroquinone

Hydroquinone

Hydroquinone, also benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, having the chemical formula C6H42. Its chemical structure, shown in the table at right, has two hydroxyl groups bonded to a benzene ring in a para position. It is a white granular solid...

, which is now banned in many countries.

In vitro studies of human melanocytes exposed to arbutin at concentrations below 300 μg/mL reported decreased tyrosinase activity and melanin content with little evidence of cytotoxicity.

Risks

Arbutin is glucosylated

Glucoside

A glucoside is a glycoside that is derived from glucose. Glucosides are common in plants, but rare in animals. Glucose is produced when a glucoside is hydrolysed by purely chemical means, or decomposed by fermentation or enzymes....

 hydroquinone

Hydroquinone

Hydroquinone, also benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, having the chemical formula C6H42. Its chemical structure, shown in the table at right, has two hydroxyl groups bonded to a benzene ring in a para position. It is a white granular solid...

, and may carry similar cancer risks, although there are also claims that arbutin reduces cancer risk. The German Institute of Food Research in Potsdam

Potsdam

Potsdam is the capital city of the German federal state of Brandenburg and part of the Berlin/Brandenburg Metropolitan Region. It is situated on the River Havel, southwest of Berlin city centre....

 found that intestinal bacteria can transform arbutin into hydroquinone, which creates an environment favorable 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. It also has an anti-glycation activity.