# Dihydroxyacetone

The dihydroxyacetone , or DHA , is a Ose composed of three atoms of Carbone, which makes a Triose of it. Its empirical formula is C 3 H 6 O 3. It is a Cétose because its grouping Carbonyle is located in medium of carbonaceous chain. Contrary to its isomer Aldose, the Glycéraldéhyde, it is not a chiral molecule, since it does not have any asymmetrical carbon.

One of the characteristics of dihydroxyacetone is that its functional groups have elements of symmetry. The molecule itself presents a axial Symétrie, i.e. it is superposable with its image in a Miroir (the oxygen carried by the second carbon is placed on the right), contrary to all the others Ose S known as an indication, characteristic which makes an exception of it among the Monosaccharide S.

Diagram of the molecule:

$\begin\left\{array\right\}\left\{lcl\right\} & \ rm \left\{\ color \left\{White\right\} H\right\} OH \ \ &|\ \ & \ rm H-C - H \ \ &|\ \ & \left\{\ color \left\{White\right\} \ rm O=\right\} \ rm C =O \ \ &|\ \ & \ rm H-C - H \ \ &|\ \ & \ rm \left\{\ color \left\{White\right\} H\right\} OH \ \ \end\left\{array\right\}$

It is produced naturally by bacterial bioconversion of Glycérol.

## Esthetic uses

Generally obtained corn or cane with sugar, the DHA is frequently used in Cosmétique, in particular it constitutes the molecule for the development of the current Autobronzant S. The DHA acts by Réaction of Maillard on the Kératine S of the Couche cornea of the Peau, thus creating a tan of aspect more natural than traditional the autobronzants giving a color in the your S orange. The frequent renewal of the cornea layer (made up mainly of dead cells) explains the progressive disappearance of coloring.

This method of artificial Bronzage by no means utilizes the Mélanocyte S and there is not production of Mélanine. The tanning by application of DHA thus does not have so to speak a protective effect with respect to radiations Ultraviolet your like that ensured by the mélanine. There is absorbtion in certain cases of UVA, slightly energy, but not of UVB, conveying a more important energy, which represents a greater danger of the exposure to the Sun.

Because of its nonpenetration beyond the cornea layer, no awkward side effect is currently known with the application of DHA on the skin. An increased coloring of the Comédon S (“black spots”) can be observed.

## Dihydroxyacetone phosphates

Dihydroxyacetone phosphates or phosphodihydroxyacétone (PDHA), is one of the intermediaries of the Glycolyse.

Diagram of the molecule, the grouping Phosphate being in red:

$\begin\left\{array\right\}\left\{lcl\right\} & \ rm \left\{\ color \left\{White\right\} H\right\} OH \ \ &|\ \ & \ rm H-C - H \ \ &|\ \ & \left\{\ color \left\{White\right\} \ rm O=\right\} \ rm C =O \ \ &|\ \ & \ rm H-C - H \ \ &|\ \ & \ rm O \ \ &|\ \ & \left\{\ color \left\{Red\right\} \ rm \left\{^-\right\} O-P-O^-\right\} \ \ & \left\{\ color \left\{Red\right\}||\right\} \ \ & \left\{\ color \left\{Red\right\} \ rm O\right\} \ \ \end\left\{array\right\}$

The PDHA is produced by Clivage aldolic fructose-1,6-bisphosphate with like coproduit the Glycéraldéhyde-3-phosphate. It is a reversible reaction whose Enzyme is the Aldolase.

As only the glycéraldéhyde-3-phosphate is substrate for the continuation of glycolysis, the PDHA is entirely transformed into glycéraldéhyde-3-phosphate by isomerization, catalyzed by the triose phosphate isomérase.

Shéma of the reaction:

## External bonds

• To observe and handle a three-dimensional dihydroxyacetone model

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