D-Erythrulose (also known as erythrulose) is a tetrose carbohydrate with the chemical formula C4H8O4. It has one ketone group and so is part of the ketose family. It is used in some self-tanning cosmetics, in general, combined with dihydroxyacetone (DHA). Erythrulose/DHA reacts with the amino acids in the proteins of the first layers of skin (the ... Found on http://en.wikipedia.org/wiki/Erythrulose