Dehydroascorbic acid
IUPAC name	(5R)-5-[(1S)-1,2-dihydroxyethyl]furan-2,3,4(5H)-trione
Identifiers
CAS number	490-83-5
PubChem	7786
SMILES	O=C1C(=O)O[C@@H](C1=O)[C@@H](O)CO
Properties
Molecular formula	C6H6O6
Molar mass	174.11 g mol−1
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Dehydroascorbic acid (DHA) is an oxidized form of ascorbic acid. It is actively imported into the endoplasmic reticulum of cells and generates the oxidative potential found there. Protein disulfide isomerases are known to reduce DHA back to ascorbic acid, oxidizing their disulfide bonds in the process. Therefore L-dehydroascorbic acid is a vitamin C compound much like L-ascorbic acid. Oxidized forms of esterified ascorbic acids can be numbered at C(5) or C(6) atoms and the (free) chemical radical semi-dehydroascorbate or semidehydro ascorbic acid (SDA) to the group of dehydroascorbic acids.

[edit] Physiology

Top: ascorbic acid
(reduced form of Vitamin C)
Bottom: dehydroascorbic acid
(oxidized form of Vitamin C)

Although there exists a transporter for Vitamin C, it is mainly present in specialized cells, whereas the glucose transporters, most notably GLUT1, ensure in most cells of the body the transport of vitamin C (in its oxidized form, DHA)^[1] where it is required as an enzyme cofactor and an intracellular antioxidant, after it is recycled back to ascorbic acid (see Transport to mitochondria).

[edit] Transport to mitochondria

Vitamin C accumulates in mitochondria, where most of the free radicals are produced, by entering through the glucose transporters, GLUT1. It is the oxidized form (dehydroascorbic acid) that is transported by GLUT1, not the reduced form (ascorbic acid). Ascorbic acid protects the mitochondrial genome and membrane.^[1]

[edit] Transport to the brain

Vitamin C does not pass from the blood stream into the brain, although the brain is one of the organs which has the greatest concentration of vitamin C. Instead it is dehydroascorbate that is transported through the blood-brain barrier via GLUT1 transporters, and then converted to vitamin C. Some research has suggested that administration of dehydroascorbic acid may confer protection from neuronal injury following an ischemic stroke.^[2]

[edit] References

[edit] Further reading

• Nualart F, Rivas C, Montecinos V, Godoy A, Guaiquil V, Golde D, Vera J (2003). "Recycling of vitamin C by a bystander effect". J Biol Chem 278 (12): 10128–33. doi:10.1074/jbc.M210686200. PMID 12435736. http://www.jbc.org/cgi/content/full/278/12/10128.