One of Over 700 Sites
	with Guide Alan Bruzel, Ph.D. Bio | Contact

Subjects

Acids Bases pH Analytical Chem Ask an Expert Astrochemistry Atomic Structure Biochemistry Chemical Databases Chemical Warfare Chemistry Clip Art Chemistry History Chromatography Computational Chem Convert/Calculate Crystallography Electrochemistry Environmental Chem Fun Sites General Chemistry Graphics Software How Things Work Inorganic Chem K-12 Grade Lessons Organic Chemistry Periodic Tables Physical Chemistry Polymer Chemistry Spectroscopy Stoichiometry Terminology Toxic Chemicals Subject Library  All articles on this topic

More Sites On This Topic

Apply to become a partner for this site.

Arbutin, Hydroquinone, and Skin Lightening

Dateline: 06/05/00

By Alan Bruzel

We brook no quarrels with those we consider beneath us, especially if they offer no resistance. We then take what they produce, and fashion it to serve our purposes. From a chemistry perspective, this manifests itself in our treatment of those laboratories of complicated molecules: the members of the plant kingdom. We partake of their many products by eating, drinking, smoking, and, in the example cited below, by rubbing them on our skins.

Consider the bearberry (Arctostaphylos uva-ursi). The leaves of this evergreen shrub contain as much as nine percent of the glucoside arbutin. A glucoside results when a molecule bonds to the simple sugar glucose. Arbutin (also called hydroquinone-beta-D-glucopyranoside) consists of a molecule of hydroquinone bound to glucose.

ß-D-(+)-Glucose	Hydroquinone

It is rather interesting how plants produce a compound for one purpose, and humans use this compound for a completely unrelated purpose. Now, bearberry thrives in dry, sandy soil. It is known that arid conditions increase the concentration of glucose and therefore encourage the production of glucosides in plant cells. This desiccation-tolerant plant is thought to employ arbutin to protect its delicate cell membranes from the effects of low environmental moisture.

Humans use hydroquinone to minimize areas of hyperpigmentation, or just as a general lightener for dark skin. Unfortunately for some users, hydroquinone can promote exogenous ochronosis: an increase in pigmentation and the deposition of ochre-colored fibers in the skin. This has caused enough concern for South Africa (where high strength preparations of hydroquinone creams are marketed) to ban sale of hydroquinone-containing skin lightening products. European nations have stopped sales of hydroquinone depigmenting creams because of that compound's mutagenic activity.

Enter bearberry, or more specifically, its active ingredient, arbutin. Unlike hydroquinone, which simply kills pigment-producing cells (melanocytes), arbutin's purported means of suppressing unwanted pigmentation is to block the activity of tyrosinase, the enzyme that catalyzes the first step in melanin (a black pigment) biosynthesis. Arbutin would perform this task by mimicking the amino acid tyrosine, which is the usual substrate of tyrosinase. Further investigations into arbutin's mode of action will determine if this plant substance can effectively replace hydroquinone as a skin-lightening agent.

Arbutin	Tyrosine

What the Web Has to Say about:
Arbutin, Hydroquinone, and Skin Lightening

Arctostaphylos uva-ursi
Botanical guide from the Fire Effects Information System, US Department of Agriculture.

Arctostaphylos uva-ursi
How and why people have used this medicinal plant. From the University of Washington, Medicinal Herb Garden.

Buying a Dream, but Sold a Lie
Health problems related to higher concentrations of hydroquinone-containing skin lightening creams being sold to African consumers. From the Daily Mail & Guardian.

Eumelanin and Pheomelanin
An article from this Web site describing tyrosine's transformation to these skin and hair pigments.

Skin Lightening/Skin Depigmenting Agents
Mechanisms and properties of these skin-bleaching materials. From eMedicine.com.

Swaziland Plans Bill To Ban Skin-Lightening Creams
These lotions, banned in South Africa, are making their way into Swaziland. From Africa News Online.

Uva ursi (Arctostaphylos uva-ursi)
Active ingredients and on-going studies of this alternative medication. From Natural Medicine Online.

Uva Ursi Leaf
History, dosages, and drug interactions. From OnHealth.com.

Previous Articles

Subscribe to The Chemistry Newsletter
Name	Email