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Names | |
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IUPAC name L-threo-Hexo-2,3-diulosono-1,4-lactone | |
Systematic IUPAC name (5R)-5-[(1S)-1,2-Dihydroxyethyl]oxolane-2,3,4-trione | |
Identifiers | |
3D model (JSmol) | |
ChEBI | |
ChemSpider | |
ECHA InfoCard | 100.007.019 |
PubChem CID | |
UNII | |
CompTox Dashboard (EPA) | |
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Properties | |
C6H6O6 | |
Molar mass | 174.108 g·mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Dehydroascorbic acid (DHA) is an oxidized form of ascorbic acid (vitamin C). It is actively imported into the endoplasmic reticulum of cells via glucose transporters. [1] It is trapped therein by reduction back to ascorbic acid by glutathione and other thiols. [2] The (free) chemical radical semidehydroascorbic acid (SDA) also belongs to the group of oxidized ascorbic acids.
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Although sodium-dependent transporters for vitamin C exists, it is present mainly in specialized cells whereas the glucose transporters, most notably GLUT1, transport DHA in most cells, [3] where recycling back to ascorbic acid generates the necessary enzyme cofactor and intracellular antioxidant, (see Transport to mitochondria).
The structure shown here for DHA is the commonly shown textbook structure. This 1,2,3-tricarbonyl is too electrophilic to survive more than a few milliseconds in aqueous solution, however. The actual structure shown by spectroscopic studies is the result of rapid hemiketal formation between the 6-OH and the 3-carbonyl groups. Hydration of the 2-carbonyl is also observed. [4] The lifetime of the stabilized species is commonly said to be about 6 minutes under biological conditions. [1] Destruction results from irreversible hydrolysis of the lactone bond, with additional degradation reactions following. [5] Crystallization of solutions of DHA gives a pentacyclic dimer structure of indefinite stability. Recycling of vitamin C via active transport of DHA into cells, followed by reduction and reuse, mitigates the inability of humans to synthesize it from glucose. [6]
Vitamin C accumulates in mitochondria, where most of the free radicals are produced, by entering as DHA through the glucose transporter GLUT10. Ascorbic acid protects the mitochondrial genome and membrane. [3]
Vitamin C does not pass from the bloodstream into the brain, although the brain is one of the organs that have the greatest concentration of vitamin C. Instead, DHA is transported through the blood–brain barrier via GLUT1 transporters, and then reduced back to ascorbic acid. [8]
Dehydroascorbic acid has been used as a vitamin C dietary supplement. [9]
As a cosmetic ingredient, dehydroascorbic acid is used to enhance the appearance of the skin. [10] It may be used in a process for permanent waving of hair [11] and in a process for sunless tanning of skin. [12]
In a cell culture growth medium, dehydroascorbic acid has been used to assure the uptake of vitamin C into cell types that do not contain ascorbic acid transporters. [13]
As a pharmaceutical agent, some research has suggested that administration of dehydroascorbic acid may confer protection from neuronal injury following an ischemic stroke. [8] The literature contains many reports on the antiviral effects of vitamin C, [14] and one study suggests dehydroascorbic acid has stronger antiviral effects and a different mechanism of action than ascorbic acid. [15] Solutions in water containing ascorbic acid and copper ions and/or peroxide, resulting in rapid oxidation of ascorbic acid to dehydroascorbic acid, have been shown to possess powerful but short-lived antimicrobial, antifungal, and antiviral properties, and have been used to treat gingivitis, periodontal disease, and dental plaque. [16] [17] A pharmaceutical product named Ascoxal is an example of such a solution used as a mouth rinse as an oral mucolytic and prophylactic agent against gingivitis. [17] [18] Ascoxal solution has also been tested with positive results as a treatment for recurrent mucocutaneous herpes, [18] and as a mucolytic agent in acute and chronic pulmonary disease such as emphysema, bronchitis, and asthma by aerosol inhalation. [19]
Ascorbic acid is an organic compound with formula C
6H
8O
6, originally called hexuronic acid. It is a white solid, but impure samples can appear yellowish. It dissolves freely in water to give mildly acidic solutions. It is a mild reducing agent.
Vitamin C is a water-soluble vitamin found in citrus and other fruits, berries and vegetables. It is also a generic prescription medication and in some countries is sold as a non-prescription dietary supplement. As a therapy, it is used to prevent and treat scurvy, a disease caused by vitamin C deficiency.
PEP group translocation, also known as the phosphotransferase system or PTS, is a distinct method used by bacteria for sugar uptake where the source of energy is from phosphoenolpyruvate (PEP). It is known to be a multicomponent system that always involves enzymes of the plasma membrane and those in the cytoplasm.
L-Gulonolactone oxidase is an enzyme that produces vitamin C. It is expressed in mice and rats, but is non-functional in Haplorrhini, in some bats, and in guinea pigs. It catalyzes the reaction of L-gulono-1,4-lactone with oxygen to form L-xylo-hex-3-gulonolactone (2-keto-gulono-γ-lactone) and hydrogen peroxide. It uses FAD as a cofactor. The L-xylo-hex-3-gulonolactone then converts to ascorbic acid spontaneously, without enzymatic action.The structure of L-gulonolactone oxidase in rats helps identify characteristics of this enzyme.
Glucuronic acid is a uronic acid that was first isolated from urine. It is found in many gums such as gum arabic, xanthan, and kombucha tea and is important for the metabolism of microorganisms, plants and animals.
Glucose transporters are a wide group of membrane proteins that facilitate the transport of glucose across the plasma membrane, a process known as facilitated diffusion. Because glucose is a vital source of energy for all life, these transporters are present in all phyla. The GLUT or SLC2A family are a protein family that is found in most mammalian cells. 14 GLUTS are encoded by the human genome. GLUT is a type of uniporter transporter protein.
Glucose transporter type 4 (GLUT4), also known as solute carrier family 2, facilitated glucose transporter member 4, is a protein encoded, in humans, by the SLC2A4 gene. GLUT4 is the insulin-regulated glucose transporter found primarily in adipose tissues and striated muscle. The first evidence for this distinct glucose transport protein was provided by David James in 1988. The gene that encodes GLUT4 was cloned and mapped in 1989.
Sodium ascorbate is one of a number of mineral salts of ascorbic acid (vitamin C). The molecular formula of this chemical compound is C6H7NaO6. As the sodium salt of ascorbic acid, it is known as a mineral ascorbate. It has not been demonstrated to be more bioavailable than any other form of vitamin C supplement.
Ascorbate peroxidase (or L-ascorbate peroxidase, APX or APEX) (EC 1.11.1.11) is an enzyme that catalyzes the chemical reaction
Glucose transporter 1, also known as solute carrier family 2, facilitated glucose transporter member 1 (SLC2A1), is a uniporter protein that in humans is encoded by the SLC2A1 gene. GLUT1 facilitates the transport of glucose across the plasma membranes of mammalian cells. This gene encodes a facilitative glucose transporter that is highly expressed in erythrocytes and endothelial cells, including cells of the blood–brain barrier. The encoded protein is found primarily in the cell membrane and on the cell surface, where it can also function as a receptor for human T-cell leukemia virus (HTLV) I and II. GLUT1 accounts for 2 percent of the protein in the plasma membrane of erythrocytes.
2,6-Dichlorophenolindophenol is a chemical compound used as a redox dye. When oxidized, DCPIP is blue with a maximal absorption at 600 nm; when reduced, DCPIP is colorless.
Glucose transporter 3, also known as solute carrier family 2, facilitated glucose transporter member 3 (SLC2A3) is a protein that in humans is encoded by the SLC2A3 gene. GLUT3 facilitates the transport of glucose across the plasma membranes of mammalian cells. GLUT3 is most known for its specific expression in neurons and has originally been designated as the neuronal GLUT. GLUT3 has been studied in other cell types with specific glucose requirements, including sperm, preimplantation embryos, circulating white blood cells and carcinoma cell lines.
A dough conditioner, flour treatment agent, improving agent or bread improver is any ingredient or chemical added to bread dough to strengthen its texture or otherwise improve it in some way. Dough conditioners may include enzymes, yeast nutrients, mineral salts, oxidants and reductants, bleaching agents and emulsifiers. They are food additives combined with flour to improve baking functionality. Flour treatment agents are used to increase the speed of dough rising and to improve the strength and workability of the dough.
Solute carrier family 23 member 2 is a protein that in humans is encoded by the SLC23A2 gene.
Solute carrier family 23 member 1 is a protein that in humans is encoded by the SLC23A1 gene.
The Reichstein process in chemistry is a combined chemical and microbial method for the production of ascorbic acid from D-glucose that takes place in several steps. This process was devised by Nobel Prize winner Tadeusz Reichstein and his colleagues in 1933 while working in the laboratory of the ETH in Zürich.
Threonic acid is a sugar acid derived from threose. The l-isomer is a metabolite of ascorbic acid. One study suggested that because l-threonate inhibits DKK1 expression in vitro, it may have potential in treatment of androgenic alopecia.
A copper nanoparticle is a copper based particle 1 to 100 nm in size. Like many other forms of nanoparticles, a copper nanoparticle can be prepared by natural processes or through chemical synthesis. These nanoparticles are of particular interest due to their historical application as coloring agents and the biomedical as well as the antimicrobial ones.
Permease of phosphotransferase system is a superfamily of phosphotransferase enzymes that facilitate the transport of L-ascorbate (A) and galactitol (G). Classification has been established through phylogenic analysis and bioinformatics.
Intravenous Ascorbic Acid or PAA, pharmacologic ascorbic acid, is a process that delivers soluble ascorbic acid directly into the bloodstream. It is not approved for use to treat any medical condition.