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Ascorbic Acid

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Name: Ascorbic Acid
Generic Names:
Trade Names: Redoxon®[32]
IUPAC name:
Molecular Formula:
Structure: [1],[33],[34],[40]
Functional Group/chemical constitution:: It has dienol structure which imparts it powerful reducing ability[2]
A reductant[3]
electron donor[35] Water-soluble[4]
At physiological pH the predominant form of ascorbate is ascorbate monoion, which is a poor electron donor and oxidizes to the energetically unfavourable neutral free radical.

ascorbic acid is a water soluble ketolactone wthtwo ionizable hydroxyl groups. Ascorbate monoion is predominant fprm at physiological pH. Ascorbate readily undergoes two consecutive, one-electron oxidation to form ascorbate radical and dehydroascorbic acid. The ascorbic radical is relatively inreactive due to resonance stabilization of the upaired electron. it readily converts into ascorbate and dehydroascorbate.[35]
ascorbic acid is white crystallinepowder, extremely water soluble[35] The ascorbate dianion forms a relatively stable semihydroascorbate radical anion and is powerful electron donor; however present in insufficient concentration at neutral pH[3].
In neutral and basic solutions, the ascorbic acid anion is readily oxidized to form a trioxo radical anion. Most phenoxyl radicals oxidize ascorbic anion by electron transfer process; however radicals such as .CH2OH, phenyl and benzene para-semiquinone, meta-hydroxyphenyl do not oxidize ascorbic anion.[6]
easily gets oxidized, soluble in water , has two ionizable groups, is a good reducing agent[7]
mono-anion of ascorbate is the predominant form in all body compartments except the gastric juice[7]
semidehydroascorbate radical derived from it. by donating one electron, has low reactivity; loss of second electron converts this radical into unstable dehydroascorbate[7]
Its a alpha-ketolactone. At physiological pH, ascorbate exists as the monovalent hydroxyl anion[1]
Also, at physiological pH, ascorbic acid (pKa, 4.2) is largely found in the anion form[8]
ascorbic acid is unstable in water and is readily oxidized under atmosphere[36]
Source: Paprika(Capsicum annuum) contains ascorbic acid in relatively large quantities and its isolation from it is fairly simple[9].
Ascorbic acid is synthesized in rodent liver, circulates in blood and is concentrated in the brain[10]
Lemon juice[11].
citrus fruits and dark-green leafy vegetables are the richest source[1]
Cellular Functions: Ascorbate keeps prosthetic metal ions and certain enzymes in their reduced form by acting as a reductant. Ascorbate protects tissues from oxidative damage by acting as free radical scavenger[12]
Ascorbic acid is suggested to have a role in lowering body’s exposure to endogenously produced mutagens[13]
Ascorbic acid participated in the detoxification of compounds by hydroxylation and maintains the cytochrome P 450 levels in liver.
Ascorbic acid is necessary for absorption and accumulation of iron and efficient functioning of immune system[14].
Ingestion of 2 and 3 g ascorbate daily enhanced neutrophil motility to a chemotactic stimulus of endotoxin-activated serum in normal volunteers[15]
Acts as a enzyme cofactor, generally for enzymes like monooxygenase or dioxygenase[1]
Ascorbic acid reported to be appeared important for normal attachment of polyribosomes to the endoplasmic reticulum[8]
vitamin C is required as a co-factor in some oxidation reactions requiring molecular Oxygen[37]
Actions & Indications: Pharmcological Action-
Free radical scavenger[12], [16] Chain-breaking antioxidant[4], [17]. Pro-oxidant activity[17].
exhibits Oxygen-detoxifying nature[38] Therapeutic benefits:
Vitamin C containing food is found to have associated with lower risk for particulary gastric and esophageal cancer[18].
beneficial effects of vitamin C supplementation for wound healing, cancer and catarect prevention, atherosclerosis prevention and enhances immune mechanism is observed[1]
Preclinical Data:
In radiotherapy of human abdominal cancers, prophylactic use of ascorbic acid is suggetsed to reduce the damage to GI tract [36] Ascorbic acid 3 gm daily regressed rectal polyp in a patient with familial polyposis[19] .
ascorbic acid, in forebrain mitochondria isolated from rats, protected from ischemia/reperfusion injury when administered prior to onset of ischemia[20].
supplemental ascorbate, 10g/day, when given to terminal cancer patients, mean survival time of patients increased significantly[21]
1g vitamin C daily for 28 days, in patients with benign peptic ulcer, exhibited protective effect against development of gastric cancer, due to its effect on DNA adduction[39] Ascorbic acid prophylaxis in coal-tar workers reduced frequency of chromosome aberrations exposed to benzene in peripheral blood lymphocytes[22]
ascorbic acid supplements has been shown to lower the incidence and severity of common cold[23]; however controveries exist to this observation[24].
ascorbic acid anion form is believed to provide protection against hepatotoxicity induced by dimethylnitrosamine[8]
Ascorbic acid has been in use as a urinary acidifying agent[25]
It is advised to a rescue team members to promptly take ascorbic acid orally whhile rescuing victims from a radiation-contaminated area just after a radiation accident or terrorism[36]
Notes: Ascorbic acid from adrenal glands retained its activity even after five times recrystallization [9]
Ascorbic acid readily found to disappear from the adrenal gands of Guinea pigs when kept on a vitamin-C free diet[9]
In a study with two species of spiny mice(Acomys russatus), high concentration of ascorbic acid in eye lens is suggested to be an adaptation that permits eye to wistand increase solar radiation[26].
6-Bromo- and 6-chloro-6-deoxy derivatives of ascorbate anion are able to transfer an electron to the oxidizing radicals .OH, Br2.- and RS[27]
vitamin C has very short life in tissue culture media[28]
Some female guinea-pigs were observed to be able to readjust their ascorbic acid metabolism in times of deficiency[29]
derivatives: The palmitoyl derivative of ascorbic acid 2-glucoside, 6-palmitoyl ascorbic acid-2-glucoside, acts as a radioprotector under in vitro, ex vivo and in vivo models. Protected cellular DNA in spleen, bone marrow, blood from gamma radiation(6 Gy)[30]
High concentration of vitamin C is shown in vitro to participate in production of hydroxyl free radicals through a Fenton reaction[31]
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2. Barabás J , Nagy E, Degrell I, Ascorbic acid in cerebrospinal fluid - a possible protection against free radicals in the brain. Arch Gerontol Geriatr. 1995;21(1):43-8.
3. Njus D et al, Concerted proton-electron transfer between ascorbic acid and cytochrome b561. Am J Clin Nutr. 1991;54(6 Suppl):1179S-1183S.
4. Sato K , Niki E, Shimasaki H, Free radical-mediated chain oxidation of low density lipoprotein and its synergistic inhibition by vitamin E and vitamin C. Arch Biochem Biophys. 1990;279(2):402-5.
5. Riabchenko NI et al, Antioxidant and prooxidant properties of the ascorbic acid, dihydroquercetine and mexidol in the radical reactions induced by the ionizing radiation and chemical reagents. Radiats Biol Radioecol. 2010;50(2):186-94.
6. Schuler RH, Oxidation of ascorbate anion by electron transfer to phenoxyl radicals. Radiat Res. 1977;69(3):417-33.
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8. Edgar JA, Ascorbic acid and biological alkylating agents. Nature. 1974;248(5444):136-7.
9. Svirbely JL, Szent-Györgyi A, The chemical nature of vitamin C. Biochem J. 1933; 27(1): 279–285.
10. Wilson JX, Ascorbic acid uptake by a high-affinity sodium-dependent mechanism in cultured rat astrocytes. J Neurochem. 1989;53(4):1064-71.
11. Waugh WA, King CG, Isolation and identification of Vitamin C*. Nutrition Reviews. 1976;34(3):81–83.
12. Padh H et al, Cellular functions of ascorbic acid. Biochem Cell Biol. 1990;68(10):1166-73.
13. Dion PW et al, The effect of dietary ascorbic acid and alpha-tocopherol on fecal mutagenicity. Mutat Res. 1982;102(1):27-37.
14. Kolb E, Recent knowledge concerning the biochemistry and significance of ascorbic acid. Z Gesamte Inn Med. 1984;39(2):21-7.
15. Anderson R et al, The effects of increasing weekly doses of ascorbate on certain cellular and humoral immune functions in normal volunteers. Am J Clin Nutr. 1980;33(1):71-6.
16. Drake IM et al, Ascorbic acid may protect against human gastric cancer by scavenging mucosal oxygen radicals. Carcinogenesis. 1996;17(3):559-62.
17. Bijur GN et al, Antimutagenic and promutagenic activity of ascorbic acid during oxidative stress. Environ Mol Mutagen. 1997;30(3):339-45.
18. Chen LH, Boissonneault GA, Glauert HP, Vitamin C, vitamin E and cancer (review). Anticancer Res. 1988;8(4):739-48.
19. DeCosse JJ et al, Effect of ascorbic acid on rectal polyps of patients with familial polyposis. Surgery. 1975;78(5):608-12.
20. Sciamanna MA , Lee CP, Ischemia/reperfusion-induced injury of forebrain mitochondria and protection by ascorbate. Arch Biochem Biophys. 1993;305(2):215-24.
21. Cameron E, Pauling L, Supplemental ascorbate in the supportive treatment of cancer: Reevaluation of prolongation of survival times in terminal human cancer*. Proc. Nati. Acad. Sci. USA 1978;75(9):4538-4542.
22. Šrám RJ et al, Effect of ascorbic acid prophylaxis on the frequency of chromosome aberrations in the peripheral lymphocytes of coal-tar workers. Mutation Research Letters. 1983;120(2–3):181-186.
23. Pauling L, Vitamin C and the common cold. Can Med Assoc J. 1971; 105(5): 448.
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25. Barness LA, Safety considerations with high ascorbic acid dosage. Ann N Y Acad Sci. 1975;258:523-8.
26. Koskela TK et al, Is the high concentration of ascorbic acid in the eye an adaptation to intense solar irradiation? Invest Ophthalmol Vis Sci. 1989 ;30(10):2265-7.
27. Bonifacić M , Ljubenkov I, Eckert-Maksić M, One-electron oxidation and reduction reactions of vitamin C derivatives: 6-bromo- and 6-chloro-6-deoxy-ascorbic acid. Int J Radiat Biol. 1994;66(2):123-31.
28. Schorah CJ, The transport of vitamin C and effects of disease. Proceedings of the Nutrition Society 1992; 51:189-198.
29. Odumosu A, Wilson CW, Metabolic availability of ascorbic acid in female guinea-pigs. Br J Pharmacol. 1971; 42(4): 637P–638P.
30. Chandrasekharan DK , Kagiya TV, Nair CK, Radiation protection by 6-palmitoyl ascorbic acid-2-glucoside: studies on DNA damage in vitro, ex vivo, in vivo and oxidative stress in vivo. J Radiat Res. 2009;50(3):203-12.
31. Cai L, Koropatnick J, Cherian MG, Roles of vitamin C in radiation-induced DNA damage in presence and absence of copper Chem Biol Interact. 2001;137(1):75-88.
32. Antunes LM, Takahashi CS, Protection and induction of chromosomal damage by vitamin C in human lymphocyte cultures. Teratog Carcinog Mutagen. 1999;19(1):53-9.
33. Rumsey SC, Levine M, Absorption, transport, and disposition of ascorbic acid in humans. The Journal of Nutritional Biochemistry 1998;9(3):116–130.
34. Bánhegyi G et al, Ascorbate metabolism and its regulation in animals. Free Radic Biol Med. 1997;23(5):793-803.
35. Du J, Cullen JJ, Buettner GR, Ascorbic acid: Chemistry, biology and the treatment of cancer. Biochim Biophys Acta. 2012;1826(2):443-57.
36. Yamamoto T et al, Pretreatment with Ascorbic Acid Prevents Lethal Gastrointestinal Syndrome in Mice Receiving a Massive Amount of Radiation. J Radiat Res. 2010;51(2):145-56
37. Morgan AR, Cone RL, Elgert TM, The mechanism of DNA strand breakage by vitamin C and superoxide and the protective roles of catalase and superoxide dismutase. Nucleic Acids Res. 1976;3(5):1139-49.
38. Yasukawa M, Terasima T, Seki M, Radiation-induced neoplastic transformation of C3H10T1/2 cells is suppressed by ascorbic acid. Radiat Res. 1989 ;120(3):456-67.
39. Dyke GW et al, Effect of vitamin C supplementation on gastric mucosal DNA damage. Carciuogenesis 1994;15(2):291-295.
40. Shamberger RJ, Genetic toxicology of ascorbic acid. Mutat Res. 1984;133(2):135-59.