Dehydroascorbic acid 2154534 216617487 2008-06-02T13:17:48Z Jll 9177 /* Transport to the brain */ {{Chembox new | Name = Dehydroascorbic acid | ImageFile = Dehydroascorbic acid.png <!-- | ImageSize = 200px --> | ImageName = | IUPACName = | Section1 = {{Chembox Identifiers | CASNo = | SMILES = }} | Section2 = {{Chembox Properties | Formula = C<sub>6</sub>H<sub>6</sub>O<sub>6</sub> | MolarMass = 174.13 g/mol | Density = | MeltingPt = | BoilingPt = }} }} '''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 isomerase]]s 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 [[Radical (chemistry)|(free) chemical radical]] semi-dehydroascorbate or semidehydro ascorbic acid (SDA) to the group of dehydroascorbic acids. ==Physiology== <div class="thumb tright" style="float: right; background-color: #f9f9f9; border: 1px solid #CCCCCC; margin:0.5em;"> {|border="0" width=150px border="0" cellpadding="2" cellspacing="0" style="font-size: 85%; border: 1px solid #CCCCCC; margin: 0.3em;" |[[Image:Ascorbic acid structure.png|150px]] |} {|border="0" width=150px border="0" cellpadding="2" cellspacing="0" style="font-size: 85%; border: 1px solid #CCCCCC; margin: 0.3em;" |[[Image:Dehydroascorbic acid.png|150px]] |} <div style="border: none; width:150px;"><div class="thumbcaption"><small>Top: [[ascorbic acid]]<br />([[reducing agent|reduced form]] of [[Vitamin C]])<br />Bottom: dehydroascorbic acid<br />([[oxidizing agent|oxidized form]] of [[Vitamin C]])</small></div></div></div> Although there exists a transporter for [[Vitamin C]], it is mainly present in specialized cells, whereas the [[glucose transporter]]s, most notably [[GLUT1]], ensure in most cells of the body the transport of vitamin C (in its oxidized form, DHA)<ref name="MitoGolde"/> where it is required as an enzyme cofactor and an intracellular antioxidant, after it is recycled back to ascorbic acid (see Transport to mitochondria). ===Transport to mitochondria=== Vitamin C accumulates in [[mitochondria]], where most of the [[free radical]]s 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 [[Mitochondrial membrane#Mitochondrion structure|membrane]].<ref name="MitoGolde"> {{cite journal |author=KC S, Carcamo JM, Golde DW |title=Vitamin C enters mitochondria via facilitative glucose transporter 1 (Glut1) and confers mitochondrial protection against oxidative injury |url=http://www.fasebj.org/cgi/content/full/19/12/1657 |journal=FASEB J |volume=19 |issue=12 |pages=1657–67 |year=2005 |pmid=16195374 |doi=10.1096/fj.05-4107com}}</ref> ===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|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]].<ref name="ascorBBB">{{cite journal |author=Huang J, Agus DB, Winfree CJ, Kiss S, Mack WJ, McTaggart RA, Choudhri TF, Kim LJ, Mocco J, Pinsky DJ, Fox WD, Israel RJ, Boyd TA, Golde DW, Connolly ES Jr. |title=Dehydroascorbic acid, a blood-brain barrier transportable form of vitamin C, mediates potent cerebroprotection in experimental stroke |url=http://www.pnas.org/cgi/content/full/98/20/11720 |journal=Proceedings of the National Academy of Sciences |volume=98 |issue=20 |pages=11720–11724 |year=2001 |pmid=11573006 |doi=10.1073/pnas.171325998}}</ref> {{-}} ==References== {{Reflist}} ==Further reading== * {{cite journal |author=Nualart F, Rivas C, Montecinos V, Godoy A, Guaiquil V, Golde D, Vera J |title=Recycling of vitamin C by a bystander effect |journal=J Biol Chem |volume=278 |issue=12 |pages=10128–33 |year=2003 |pmid=12435736 | url = http://www.jbc.org/cgi/content/full/278/12/10128 |doi=10.1074/jbc.M210686200 }} [[Category:Organic acids]] [[Category:Neurology]] [[de:Dehydroascorbinsäure]]