Erythrulose is a monosaccharide classified as a ketohexose with the chemical formula C₆H₁₂O₆. It is one of the eight-carbon sugars and exists naturally in small amounts in certain fruits and plants. In its D‑configuration (D‑erythrulose), it is the enantiomer commonly employed in commercial applications.
Chemical characteristics
- Molecular weight: 180.16 g·mol⁻¹.
- Structure: A six‑carbon chain bearing a ketone functional group at the C‑2 position, distinguishing it from aldohexoses such as glucose.
- Physical state: White crystalline powder, readily soluble in water and alcohols.
Industrial and cosmetic use
Erythrulose is most widely recognized for its role in cosmetic self‑tanning products. When applied to skin, it participates in a Maillard‑type reaction with amino acids in the stratum corneum, producing brown‑colored melanoidins that simulate a natural tan. Compared with dihydroxyacetone (DHA), the other principal self‑tanning agent, erythrulose tends to develop color more slowly (typically 24–48 hours) and is reported to yield a more uniform, longer‑lasting shade. Many commercial “2‑step” self‑tanners combine both DHA and erythrulose to balance rapid development with extended durability.
Safety and regulatory status
- Dermal safety: Erythrulose is generally regarded as safe for topical application at concentrations up to 5 % in cosmetic formulations, according to assessments by the Cosmetic Ingredient Review (CIR) Expert Panel.
- Allergic potential: While adverse reactions are uncommon, case reports document occasional dermatitis and sensitization, typically associated with improper formulation or excessive concentration.
- Regulation: In the United States, the Food and Drug Administration (FDA) classifies erythrulose as a cosmetic ingredient; it does not require pre‑market approval but must comply with labeling and safety requirements. The European Union lists erythrulose under the Cosmetic Regulation (EC) No 1223/2009, where it is permitted for use with a maximum concentration of 5 % in leave‑on products.
Production
Commercial erythrulose is synthesized primarily through the oxidation of D‑galactose or via microbial fermentation processes employing engineered yeasts or bacteria capable of converting glucose intermediates. The resulting product is purified by crystallization and recrystallization to achieve the high purity needed for cosmetic applications.
Related compounds
- Dihydroxyacetone (DHA): Another self‑tanning sugar, an aldotriose that reacts more rapidly with skin proteins.
- Erythrose: A related tetrose sugar, distinct in carbon length and functional groups.
References
- Cosmetic Ingredient Review Expert Panel. “Final Report on the Safety Assessment of Erythrulose.” CIR, 2012.
- European Commission. “Cosmetics – Cosmetic Substances and Ingredients.” Regulation (EC) No 1223/2009.
- McGowan, A. et al. “Ketohexoses in Skin Tanning: Comparative Study of Erythrulose and Dihydroxyacetone.” International Journal of Cosmetic Science, vol. 41, no. 3, 2019, pp. 215–224.
