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Vitamin C atawa L-askorbat téh hiji zat gizi ésénsial pikeun primata luhur jeung sababaraha spésiés lianna. Askorbat perlu pikeun sababaraha rupa réaksi métabolismeu dina sakabéh awak sato jeung tutuwuhan sarta dihasilkeun ku awak ampir sakabéh organismeu, iwal manusa jeung sababaraha primata. Ieu vitamin kawentar ku balukar tina kakuranganana: barusuh (skorbut)^[1]^[2]^[3].

Farmakofor vitamin C téh ion askorbatna. Pikeun mahluk hirup, askorbat téh antioksidan anu naméngan awak tina setrés oksidatif^[4] sarta salaku kofaktor dina sababaraha réaksi énzimatik penting^[5].

Peran biologis

Vitamin C téh L-énantiomér askorbat; énantiomér sabalikna, D-énantiomér, teu boga mangpaat fisiologis anu penting. Duanana mangrupa kiral pikeun wangun molekul anu sarua. Nalika ngaréduksi, L-askorbat nu réduktor kuat téh bakal robah jadi bentuk kaoksidasi, L-dehidroaskorbat^[5]. L-dehidroaskorbat lajeng bisa diréduksi balik jadi L-askorbat aktif ku énzim jeung glutation^[6].

L-askorbat téh asam gula lemah anu wangunna patali jeung glukosa nu sacara alami diciptakeun ngahiji jeung ion hidrogén ngabentuk assam askorbat, atawa ngahiji jeung ion logam ngabentuk askorbat mineral.

Mangpaat

Pikeun manusa, vitamin C jétu pisan salaku antioksidan, ngurangan setrés oksidatif, salaku substrat peroksidaseu askorbat^[3], ogé salaku kofaktor énzim dina biosintésis bahan-bahan biokimia penting. Vitamin C boga peran salaku donor éléktron pikeun dalapan énzim^[7]:

Tilu énzim dina hidroksilasi kolagén^[8]^[9]^[10]. Ieu réaksi nambahkeun gugus hidroksil kana asam amino prolin atawa lisin dina molekul molekul (ngaliwatan hidroksilaseu prolil jeung hidroksilaseu lisil), antukna molekul kolagénna bisa ngabentuk wangun tripel héliks; ku kituna vitamin C jadi éséntial pikeun kamekarkeun jeung mulasara jaringan tatu, saluran getih, jeung kartilage^[11].
Dua énzim pikeun sintésis karnitin^[12]^[13]. Karnitin penting dina ngakut asam lemak ka mitokondria pikeun ngahasilkeun ATP.
Anu tilu sésana nyaéta
- hidroksilaseu béta dopamin dina biosintésis norépinéfrin tina dopamin^[14]^[15].
- énzim nu nambahkeun gugus amida ka hormon péptida, antukna leuwih stabil^[16]^[17].
- énzim nu ngamodulasi métabolismeu tirosin^[18]^[19].

Jaringan biologis anu ngagundukkeun vitamin C leuwih ti 100 kali kadarna dina plasma getih nyaéta kelenjar adrénal, pituitari, timus, corpus luteum, jeung rétina^[20]. Nu ngagundukkeun antara 10 n.k. 50 kalina nyaéta otak, limpa, bayah, téstis, kelenjar limfe, ati, tiroid, mukosa usus leutik, leukosit, pangkréas, ginjal, jeung kelenjar ciduh.

Rujukan

Vitamin C. Wikipédia basa Inggris (5 Dés. 2007).

↑ "Vitamin C". Food Standards Agency (UK). Diakses tanggal 2007-02-19.
↑ "Vitamin C (Ascorbic Acid)". University of Maryland Medical Center. April 2002. Diakses tanggal 2007-02-19. Archived 2005-12-31 di Wayback Machine
↑ ^a ^b Higdon, Jane, Ph.D. (2006-01-31). "Vitamin C". Oregon State University, Micronutrient Information Center. Diakses tanggal 2007-03-07.
↑ Padayatty S, Katz A, Wang Y, Eck P, Kwon O, Lee J, Chen S, Corpe C, Dutta A, Dutta S, Levine M (2003). "Vitamin C as an antioxidant: evaluation of its role in disease prevention". J Am Coll Nutr 22 (1): 18-35. PMID 12569111. http://www.jacn.org/cgi/reprint/22/1/18.pdf. Archived 2009-09-29 di Wayback Machine
↑ ^a ^b "Vitamin C – Risk Assessment" (PDF). UK Food Standards Agency. Diakses tanggal 2007-02-19. Archived 2007-11-29 di Wayback Machine
↑ Meister A (1994). "Glutathione-ascorbic acid antioxidant system in animals". J Biol Chem 269 (13): 9397-400. PMID 8144521. http://www.jbc.org/cgi/reprint/269/13/9397.pdf. Archived 2009-09-14 di Wayback Machine
↑ Levine M, Rumsey SC, Wang Y, Park JB, Daruwala R. Vitamin C. In Stipanuk MH (ed): "Biochemical and Physiological Aspects of Human Nutrition." Philadelphia: W B Saunders, kc. 541–567, 2000.
↑ Prockop DJ, Kivirikko KI: Collagens: molecular biology, diseases, and potentials for therapy. Annu Rev Biochem 64:403–434, 1995.
↑ Peterkofsky B: Ascorbate requirement for hydroxylation and secretion of procollagen: relationship to inhibition of collagen synthesis in scurvy. Am J Clin Nutr 54: 1135S–1140S, 1991.
↑ Kivirikko KI, Myllyla R: Post-translational processing of procollagens. Ann N Y Acad Sci 460: 187–201, 1985.
↑ McGee, William, M.D., M.H.A., Assistant Professor of Medicine and Surgery, Tufts University School of Medicine; Medical Encyclopedia: Ascorbic acid
↑ Rebouche CJ: Ascorbic acid and carnitine biosynthesis. Am J Clin Nutr 54:1147S–1152S, 1991.
↑ Dunn WA, Rettura G, Seifter E, Englard S. Carnitine biosynthesis from gamma-butyrobetaine and from exogenous protein-bound 6-N-trimethyl-L-lysine by the perfused guinea pig liver. Effect of ascorbate deficiency on the in situ activity of gammabutyrobetaine hydroxylase. J Biol Chem 259:10764–10770, 1984.
↑ Levine M, Dhariwal KR, Washko P, Welch R, Wang YH, Cantilena CC, Yu R: Ascorbic acid and reaction kinetics in situ: a new approach to vitamin requirements. J Nutr Sci Vitaminol (Tokyo) Spec No:169–172, 1992.
↑ Kaufman S: Dopamine-beta-hydroxylase. J Psychiatr Res 11: 303–316, 1974.
↑ Eipper BA, Milgram SL, Husten EJ, Yun HY, Mains RE: Peptidylglycine alpha-amidating monooxygenase: a multifunctional protein with catalytic, processing, and routing domains. Protein Sci 2:489–497, 1993.
↑ Eipper BA, Stoffers DA, Mains RE: The biosynthesis of neuropeptides: peptide alpha-amidation. Annu Rev Neurosci 15:57–85, 1992.
↑ Englard S, Seifter S (1986). "The biochemical functions of ascorbic acid". Annu. Rev. Nutr. 6: 365-406. doi:10.1146/annurev.nu.06.070186.002053. PMID 3015170.
↑ Lindblad B, Lindstedt G, Lindstedt S: The mechanism of enzymic formation of homogentisate from p-hydroxyphenylpyruvate. J Am Chem Soc 92:7446–7449, 1970.
↑ New view at C Matthias A. Hediger , Nature Medicine 8, 445 - 446 (2002) doi:10.1038/nm0502-445
"Plasma vitamin C concentrations are maintained between 10 and 160 μM, and any excess of the vitamin is excreted by the kidney. In contrast, the vitamin is concentrated to at least 100 times the plasma level in specific tissues such as the adrenal glands, pituitary gland, thymus, retina, corpus luteum, and a variety of neuronal cell types."

Bacaan salajengna

Jurnal

Dolske, M.C., et al. (1993). "A preliminary trial of ascorbic acid as supplemental therapy for autism". Prog. Neuropsychopharmacol. Biol. Psychiatry 17 (5): 765-74. PMID 8255984.
Green VA, Pituch KA, Itchon J, Choi A, O'Reilly M, Sigafoos J (2006). "Internet survey of treatments used by parents of children with autism". Research in developmental disabilities 27 (1): 70-84. doi:10.1016/j.ridd.2004.12.002. PMID 15919178.

Pustaka

Pauling, Linus (1970). Vitamin C and the Common Cold. W. H. Freeman & Company. ISBN 071670160X.
Pauling, Linus (1976). Vitamin C, the Common Cold, and the Flu. W H Freeman & Co. ISBN 0716703610.
Cameron, Ewan; Linus Pauling, (1979). Cancer and Vitamin C. Pauling Institute of Science and Medicine. ISBN 0393500004. Text "Ewan Cameron " ignored (bantuan);
Kent, Saul (1980). Life Extension Revolution. Morrow.
Pearson, Durk; Sandy Shaw (1982). Life Extension: A Practical Scientific Approach. Warner Books. ISBN 0446387355. see Part IV, Chapter 7: Vitamin C
Pelton, Ross (1986). Mind Food and Smart Pills: How to Increase Your Intelligence and Prevent Brain Aging. T & R Pub. ISBN 0936809000. see Chapter 3: Vitamin C, The Champion Free Radical Scavenger
Clemetson, C.A.B (1989). Vitamin C. Boca Raton, Florida: CRC Press. ISBN 0-8493-4841-2. Monograph - Volumes I, II, III.
Levy, Thomas E. (2002). Vitamin C Infectious Diseases, & Toxins. Xlibris. ISBN 1401069630.

Tumbu kaluar

AscorbateWeb — a collection of twentieth century medical & scientific literature on vitamin C in the tréatment and prevention of human diséase at séanet.com
Healing Thresholds — Research on Vitamin C in the treatment of autism. at héalingthresholds.com
U.S. Patent 5278189 — "Prevention and treatment of occlusive cardiovascular disease with ascorbate and substances that inhibit the binding of lipoprotein (a)", Inventors: Matthias W. Rath and Linus C. Pauling
vitamin C at United Kingdom Food Standards Agency
Naidu KA (2003). "Vitamin C in human health and disease is still a mystery? An overview". Nutrition journal 2: 7. doi:10.1186/1475-2891-2-7. PMID 14498993. http://www.nutritionj.com/content/2/1/7.
Vitamin C Requirements: Optimal Health Benefits vs Overdose — a moderate dose advocacy site
For Doctors: Preparation of Vitamin C IV's — by Andrew W. Saul, PhD. at doctoryourself.com
Information regarding treatment of the Bird Flu with massive doses of ascorbate. — by Robert Cathcart, M.D. at orthomed.com

Artikel ieu mangrupa taratas, perlu disampurnakeun. Upami sadérék uninga langkung paos perkawis ieu, dihaturan kanggo ngalengkepan.

[UKFSA-1] "Vitamin C". Food Standards Agency (UK). Diakses tanggal 2007-02-19.

[UMM-2] "Vitamin C (Ascorbic Acid)". University of Maryland Medical Center. April 2002. Diakses tanggal 2007-02-19. Archived 2005-12-31 di Wayback Machine

[OSU-3] Higdon, Jane, Ph.D. (2006-01-31). "Vitamin C". Oregon State University, Micronutrient Information Center. Diakses tanggal 2007-03-07.

[Padayatty-4] Padayatty S, Katz A, Wang Y, Eck P, Kwon O, Lee J, Chen S, Corpe C, Dutta A, Dutta S, Levine M (2003). "Vitamin C as an antioxidant: evaluation of its role in disease prevention". J Am Coll Nutr 22 (1): 18-35. PMID 12569111. http://www.jacn.org/cgi/reprint/22/1/18.pdf. Archived 2009-09-29 di Wayback Machine

[UKFSA_Risk-5] "Vitamin C – Risk Assessment" (PDF). UK Food Standards Agency. Diakses tanggal 2007-02-19. Archived 2007-11-29 di Wayback Machine

[6] Meister A (1994). "Glutathione-ascorbic acid antioxidant system in animals". J Biol Chem 269 (13): 9397-400. PMID 8144521. http://www.jbc.org/cgi/reprint/269/13/9397.pdf. Archived 2009-09-14 di Wayback Machine

[7] Levine M, Rumsey SC, Wang Y, Park JB, Daruwala R. Vitamin C. In Stipanuk MH (ed): "Biochemical and Physiological Aspects of Human Nutrition." Philadelphia: W B Saunders, kc. 541–567, 2000.

[8] Prockop DJ, Kivirikko KI: Collagens: molecular biology, diseases, and potentials for therapy. Annu Rev Biochem 64:403–434, 1995.

[9] Peterkofsky B: Ascorbate requirement for hydroxylation and secretion of procollagen: relationship to inhibition of collagen synthesis in scurvy. Am J Clin Nutr 54: 1135S–1140S, 1991.

[10] Kivirikko KI, Myllyla R: Post-translational processing of procollagens. Ann N Y Acad Sci 460: 187–201, 1985.

[11] McGee, William, M.D., M.H.A., Assistant Professor of Medicine and Surgery, Tufts University School of Medicine; Medical Encyclopedia: Ascorbic acid

[12] Rebouche CJ: Ascorbic acid and carnitine biosynthesis. Am J Clin Nutr 54:1147S–1152S, 1991.

[13] Dunn WA, Rettura G, Seifter E, Englard S. Carnitine biosynthesis from gamma-butyrobetaine and from exogenous protein-bound 6-N-trimethyl-L-lysine by the perfused guinea pig liver. Effect of ascorbate deficiency on the in situ activity of gammabutyrobetaine hydroxylase. J Biol Chem 259:10764–10770, 1984.

[14] Levine M, Dhariwal KR, Washko P, Welch R, Wang YH, Cantilena CC, Yu R: Ascorbic acid and reaction kinetics in situ: a new approach to vitamin requirements. J Nutr Sci Vitaminol (Tokyo) Spec No:169–172, 1992.

[15] Kaufman S: Dopamine-beta-hydroxylase. J Psychiatr Res 11: 303–316, 1974.

[16] Eipper BA, Milgram SL, Husten EJ, Yun HY, Mains RE: Peptidylglycine alpha-amidating monooxygenase: a multifunctional protein with catalytic, processing, and routing domains. Protein Sci 2:489–497, 1993.

[17] Eipper BA, Stoffers DA, Mains RE: The biosynthesis of neuropeptides: peptide alpha-amidation. Annu Rev Neurosci 15:57–85, 1992.

[18] Englard S, Seifter S (1986). "The biochemical functions of ascorbic acid". Annu. Rev. Nutr. 6: 365-406. doi:10.1146/annurev.nu.06.070186.002053. PMID 3015170.

[19] Lindblad B, Lindstedt G, Lindstedt S: The mechanism of enzymic formation of homogentisate from p-hydroxyphenylpyruvate. J Am Chem Soc 92:7446–7449, 1970.

[20] New view at C Matthias A. Hediger , Nature Medicine 8, 445 - 446 (2002) doi:10.1038/nm0502-445
"Plasma vitamin C concentrations are maintained between 10 and 160 μM, and any excess of the vitamin is excreted by the kidney. In contrast, the vitamin is concentrated to at least 100 times the plasma level in specific tissues such as the adrenal glands, pituitary gland, thymus, retina, corpus luteum, and a variety of neuronal cell types."

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