How do skin lighteners work? Arbutin's role in cosmetics

At one point or another we've all seen our mothers or grandmothers dabbing their face with cream. Look inside their purse and you'll find a small container called "Skin Lightening Cream" boasting to "get rid of all your dark spots to make you look 10 years younger!" Have you ever stopped to ask yourself just how these creams can lighten your skin? Well many utilize a chemical called arbutin to aid in this effort. Arbutin inhibits the enzyme tyrosinase - an enzyme that controls the synthesis of melanin. Inhibit this enzyme and produce less melanin, thus making less pigment and lightening the skin.

Structure of tyrosinase 

Simply put, arbutin is a chemical with a glucose attached to a hydroquinone - an organic compound featuring two hydroxyl groups bonded to a benzene ring.

Arbutin - glucose and hydroquinone

Hydroquinone

However, it is important to understand that there are different types of glycosidic bonds between the glucose and hydroquinone that produce different behaviors of the chemical - namely, alpha and beta. Beta is the one that occurs naturally in the bearberry plant from which arbutin is extracted. Glucose residues in cellulose are bound by beta glycosidic linkages while glucose residues in starch are bound by alpha glycosidic linkages. Naturally extracted "beta" arbutin is common among the world of cosmetics while the "alpha" arbutin can only be produced in laboratories. 

A common point of contention among scientists today is "Is new always better?" Yes, we've have managed to engineer an alpha arbutin - but is it necessarily better than the naturally occuring beta? In fact, it would be false to suggest that merely because it is new it provides better suppression of melanin than the beta while staying just as safe as the naturally occurring arbutin. Until full toxicological tests are performed on the new chemical with positive results should the shift be made towards the new alpha arbutin as the most common skin lightening agent. It is in the opinion of Hannah Sivak, PhD that "novelty in a chemical is not an advantage but a problem."

Source: http://www.skinactives.com/blog/2011/04/28/guide-what-is-arbutin-the-most-common-skin-lightener/


andrew kang