Dihydroxyacetone

Dihydroxyacetone
IUPAC name	1,3-Dihydroxypropan-2-one
Other names	Dihydroxyacetone DHA Glycerone
Identifiers
CAS number	96-26-4 Y
EC-number	202-494-5
SMILES	OCC(=O)CO
InChI	1/C3H6O3/c4-1-3(6)2-5/h4-5H,1-2H2
ChemSpider ID	650
Properties[1]
Molecular formula	C3H6O3
Molar mass	90.078 g/mol
Melting point	89–91 °C
Hazards[2]
GHS pictograms
GHS signal word	WARNING
GHS hazard statements	H319
GHS precautionary statements	P264, P280, P305+351+338, P337+313
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Dihydroxyacetone (also known as DHA, glycerone) (pronounced /ˌdаɪhаɪˌdrɒksiˈæsɛtoʊn/ ( listen)) is a simple carbohydrate that is primarily used as an ingredient in sunless tanning products. It is often derived from plant sources such as sugar beets and sugar cane, and by the fermentation of glycerin.

Chemistry

DHA is a triose carbohydrate chemical formula C₃H₆O₃. It is a hygroscopic white crystalline powder. It has a sweet cooling taste and a characteristic odor. It is the simplest of all ketoses and, having no chiral center, is the only one that has no optical activity. The normal form is a dimer which is slowly soluble in one part water and 15 parts ethanol.^[3] When freshly prepared, it reverts rapidly to the monomer in solution. The monomer is very soluble in water, ethanol, diethyl ether and acetone.

DHA may be prepared, along with glyceraldehyde, by the mild oxidation of glycerol, for example with hydrogen peroxide and a ferrous salt as catalyst.

Biology

Its phosphate form, dihydroxyacetone phosphate (DHAP) takes part in glycolysis.

Uses

DHA was first recognized as a skin coloring agent by German scientists in the 1920s. Through its use in the X-ray process, it was noted as causing the skin surface to turn brown when spilled. World War II began, and further research in this area temporarily halted as scientists contributed their resources to the war effort.

In the 1950s Eva Wittgenstein at the University of Cincinnati did further research with dihydroxyacetone.^[4][5][6][7] Her studies involved using DHA as an oral drug for assisting children with glycogen storage disease. The children received large doses of DHA by mouth, and sometimes spat or spilled the substance onto their skin. Healthcare workers noticed that the skin turned brown after a few hours of DHA exposure.

Eva Wittgenstein continued to experiment with this unique substance, painting DHA liquid solutions onto her own skin. She was able to consistently reproduce the pigmentation effect, and noted that DHA did not penetrate beyond the stratum corneum, or dead skin surface layer.

Additional research studied DHA's skin coloring effect in relation to treatment for patients suffering from vitiligo.

This skin browning effect is non-toxic, and similar to the Maillard reaction. It is more commonly seen in the food preparation industry, and was described in 1912 by Louis Camille Maillard. DHA reacts chemically with the amino acid groups, which are part of the protein containing keratin layer on the skin surface. Various amino acids react differently to DHA, producing different tones of coloration from yellow to brown. The resulting pigments are called melanoidins. These are similar in coloration to melanin, the natural substance in the deeper skin layers which brown or "tan", from exposure to UV rays.

Winemaking

Both acetic acid bacteria A. aceti and G. oxydans use glycerol as a carbon source to form dihydroxyacetone. DHA is formed by ketogenesis of glycerol into dihydroxyacetone.^[8] It can affect the sensory quality of the wine with sweet/etherish property. DHA can also react with proline to produce a "crust-like" aroma.^[9][10][11] Dihydroxyacetone can affect the anti-microbial activity in wine, as it has the ability to bind SO₂.^[12]

Sunless tanning

Coppertone introduced the first consumer sunless tanning lotion into the marketplace in the 1960s. This product was called “Quick Tan” or “QT”. It was sold as an overnight tanning agent, and other companies followed with similar products. Consumers soon tired of this product due to unattractive results such as orange palms, streaking and poor coloration. Because of the QT experience, many people today still associate sunless tanning with fake-looking orange tans.

In the 1970s the United States Food and Drug Administration (FDA) added DHA permanently to their list of approved cosmetic ingredients.^[13]

By the 1980s new sunless tanning formulations appeared on the market, and refinements in the DHA manufacturing process created products that produced a more natural looking color and better fading. Consumer concerns surrounding damage associated with UV tanning options spurred further popularity of sunless tanning products as an alternative to UV tanning. Dozens of brands appeared on drugstore shelves, in numerous formulations.

Today, dihydroxyacetone is the main active ingredient in all sunless tanning skincare preparations. It may be used alone or combined with other tanning components such as erythrulose. DHA is considered the most effective sun-free tanning additive.

Sunless tanning products contain DHA in concentrations ranging from 1% to 15%. Most drugstore products range from 3% to 5%, with professional products ranging from 5% to 15%. The percentages correspond with the product coloration levels from light to dark. Lighter products are more beginner-friendly, but may require multiple coats to produce the desired color depth. Darker products produce a dark tan in one coat, but are also more prone to streaking, unevenness, or off-color tones. The artificial tan takes 2 to 4 hours to begin appearing on the skin surface, and will continue to darken for 24 to 72 hours, depending on formulation type.

Once the darkening effect has occurred, the tan will not sweat off or wash away with soap or water. It will fade gradually over 3 to 10 days, in conjunction with the skin's normal exfoliation process. Exfoliation, prolonged water submersion, or heavy sweating can lighten the tan, as these all contribute to rapid dead skin cell exfoliation (the dead skin cells are the tinted portion of the sunless tan.)

Current sunless tanners are formulated into sprays, lotions, gels, mousses, and cosmetic wipes. Professional applied products include spray tanning booths, airbrush tan applications, and hand applied lotions, gels, mousses and wipes.

DHA does not damage the skin, and is considered a safe skin coloring agent and nutritional supplement. Contact dermatitis is rarely reported^{[citation needed]}, however a recent study showed that DHA causes severe contact dermatitis in Mexican hairless dogs ^[14]. Most cases of sensitivity are due to other ingredients in the skin product preparation, such as preservatives, plant extracts, dyes or fragrances^{[citation needed]}.

DHA has been approved for cosmetic use by the FDA, the Canadian Health Ministry, and most of the EU member nations.^{[citation needed]}

DHA-based sunless tanning has been recommended by The Skin Cancer Foundation, American Academy of Dermatology Association, Canadian Dermatology Association and the American Medical Association

Nutritional supplement

When combined with pyruvate, DHA is sold as an athletic nutritional supplement which is claimed to be an orally administered fat-burner, which is also claimed to increase lean muscle mass.^{[15][unreliable source?]}

DHA safety considerations

For the 24 hours after self-tanner is applied, the skin is especially susceptible to free-radical damage from sunlight, according to a 2007 study led by Katinka Jung of the Gematria Test Lab in Berlin^[16]. Forty minutes after the researchers treated skin samples with DHA they found that more than 180 percent additional free radicals formed during sun exposure compared with untreated skin. Another self-tanner ingredient, erythulose, produced a similar response. For a day after self-tanner application, excessive sun exposure should be avoided and sunscreen should be worn outdoors, they say; an antioxidant cream could also minimize free radical production. Although some self-tanners contain sunscreen, its effect will not last long after application, and a fake tan itself will not protect the skin from UV exposure.

The study by Jung et al. further confirms earlier results demonstrating that dihydroxyacetone in combination with dimethylisosorbide enhances the process of (sun-based) tanning. This earlier study also found that dihydroxyacetone also has an effect on the amino acids and nucleic acids which is bad for the skin.^[17]

References

External links

• How Stuff Works
• US FDA/CFSAN - Tanning Pills
• The Skin Cancer Foundation on Sunless tanners
• American Academy of Dermatology on Self Tanners
• DHA and Vitiligo
• DHA as a Vitiligo option
• Self Tanning lotions as a skin safe alternative to UV tanning
• The American Cancer Society on Sunless Tanners
• New Zealand Dermatological Society recommends sunless tanners