Arbutin

What is arbutin?

Arbutin is a natural compound that exists in 2 different configurations, alpha-arbutin and beta-arbutin (R). Beta-arbutin is found in many plants, usually in the leaves (R). However, as a skin lightening agent alpha-arbutin has been shown to be 10x more effective than beta-arbutin (R). Apart from extraction from plants, arbutin can also be obtained through chemical synthesis, biotransformation using enzymes, and microbial fermentation (R, R).

Is arbutin stable?

In cosmetic formulations, alpha-arbutin generally remains stable for several months under reasonable storage conditions (R), such as at temperatures below 40°C and pH between 4.5 and 7.5, though it may be less stable in liquid preparations (R). Beta-arbutin is known to be photosensitive however, so sunscreen agents are often added to prevent it from degrading (R).

Does arbutin get absorbed?

Arbutin's hydrophilicity impedes its ability to penetrate the skin (R). A study using human skin samples revealed that when 2% alpha-arbutin was applied, most of the applied dose remained on the surface of the skin or in the stratum corneum, with only about 0.3% reaching the epidermis, dermis and beyond (R). The absorption of beta-arbutin is similar, at about 0.2% (R). Ultrasound treatment (R), loading of arbutin on to dissolving microneedles (R, R) or nanocarriers (R, R), and encapsulating arbutin within micelles (R) can all enhance its delivery into the skin.

What happens after arbutin is absorbed?

Arbutin is a derivative of hydroquinone, a more powerful skin lightening agent. Bacteria normally present on the skin's surface can hydrolyse arbutin to hydroquinone (R), which can in turn be converted to p-benzoquinone and quickly bind to macromolecules in cells (R). Fibroblasts in the skin also contain enzymes called glucosidases that may also metabolise arbutin to hydroquinone (R).