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Taurine

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Taurine, or 2-aminoethanesulfonic acid, is an organic acid. It is also a major constituent of bile and can be found in the lower intestine and in small amounts in the tissues of many animals and in humans as well.[1][2] Taurine is a derivative of the sulfur-containing (sulfhydryl) amino acid, cysteine. Taurine is one of the few known naturally occurring sulfonic acids.

Taurine is named after the Latin taurus, which means bull or ox, as it was first isolated from ox bile in 1827 by German scientists Friedrich Tiedemann and Leopold Gmelin.[3] It is often called an amino acid, even in scientific literature,[4][5][6] but as it lacks a carboxyl group it is not strictly an amino acid.[7] It does contain a sulfonate group and may be called an amino sulfonic acid. Small polypeptides have been identified which contain taurine but to date no aminoacyl tRNA synthetase has been identified as specifically recognizing taurine and capable of incorporating it onto a tRNA.[8]

Biosynthesis

The major pathway for mammalian taurine synthesis occurs in the liver via the cysteine sulfinic acid pathway. In this pathway, the sulfhydryl group of cysteine is first oxidized to cysteine sulfinic acid by the enzyme cysteine dioxygenase. Cysteine sulfinic acid, in turn, is decarboxylated by sulfinoalanine decarboxylase to form hypotaurine. It is unclear whether hypotaurine is then spontaneously or enzymatically oxidized to yield taurine.

Taurine in the pharmaceutical and lab setting is synthesized through a combination of cysteine, methionine and vitamin E. It is naturally produced in testicles of many mammals. Urban legends surrounding the source of taurine have included bull urine extract and bull semen. While it's true that taurine is found in both sources, it is not the source of taurine in the pharmaceutical or food industry. And while taurine is sometimes extracted from the intestines of cattle, many food industry sources, including the popular energy drink Red Bull,[9] make efforts to use synthesized sources that are vegetarian friendly.

Physiological roles

Taurine is conjugated via its amino terminal group with chenodeoxycholic acid and cholic acid to form the bile salts sodium taurochenodeoxycholate and sodium taurocholate. The low pKa (1.5) of taurine's sulfonic acid group ensures that this moiety is negatively charged in the pH ranges normally found in the intestinal tract and thus improves the surfactant properties of the cholic acid conjugate, which can be found in many energy drinks today. Taurine has also been implicated in a wide array of other physiological phenomena including inhibitory neurotransmission,[10] long-term potentiation in the striatum/hippocampus, membrane stabilization, feedback inhibition of neutrophil/macrophage respiratory bursts, adipose tissue regulation, calcium homeostasis and recovery from osmotic shock. It also acts as an antioxidant.[11]

Prematurely born infants who lack the enzymes needed to convert cystathionine to cysteine may become deficient in taurine. Thus, taurine is a dietary essential nutrient in these individuals and is often added to many infant formulas as a measure of prudence. There is also evidence that taurine is beneficial for adult human blood pressure and possibly, the alleviation of other cardiovascular ailments.[12] Recent studies have also shown that taurine can influence (and possibly reverse) defects in nerve blood flow, motor nerve conduction velocity, and nerve sensory thresholds in experimental diabetic neuropathic rats.[13][14] Taurine levels were found to be significantly lower in vegans than in a control group on a standard American diet. Plasma taurine was 78% of control values, and urinary taurine 29%.[15]

According to animal studies, taurine produces anxiolytic effect and may act as a modulator or anti-anxiety agent in the central nervous system.[16][17]

Taurine is necessary for normal skeletal muscle functioning. This was shown by a 2004 study,[18] using mice with a genetic taurine deficiency. They had a nearly complete depletion of skeletal and cardiac muscle taurine levels. These mice had a reduction of more than 80% of exercise capacity compared to control mice. The authors expressed themselves as "surprised" that cardiac function showed as largely normal (given various other studies about effects of taurine on the heart).

Taurine is also used in some contact lens solutions.[19]

Taurine has also been shown in diabetic rats to decrease weight and decrease blood sugar.[20] According to one study, daily administration of 1.5g taurine had no significant effect on insulin secretion or insulin sensitivity in humans.[21] However it is possible that an effect may occur at higher dosages. There is evidence that taurine may exert a beneficial effect in preventing diabetes-associated microangiopathy and tubulointerstitial injury in diabetic nephropathy.[22][23]

In humans suffering essential hypertension, taurine supplementation resulted in measurable decreases in blood pressure.[24]

Taurine and cats

Taurine is essential for cat health, as cats cannot synthesize the compound. The absence of taurine causes a cat's retina to slowly degenerate, causing eye problems and (eventually) irreversible blindness — a condition known as central retinal degeneration (CRD)[25][26], as well as hair loss and tooth decay. In addition, taurine deficiency can cause feline dilated cardiomyopathy, and supplementation can reverse left ventricular systolic dysfunction. Taurine is now a requirement of the Association of American Feed Control Officials (AAFCO) and any dry or wet food product labeled approved by the AAFCO should have a minimum of 0.1% taurine.[27]

Taurine and bird development

Recent research has provided evidence that taurine is essential in early bird development of passerines. Many passerines, regardless of spider availability, seek out many taurine-rich spiders to feed their young particularly in their youngest stages of life. Researchers later compared the behaviors and development of birds fed a taurine-supplemented diet to a control diet and found that juveniles that were fed taurine-rich diets as neonates were much larger risk takers and more adept at spatial learning tasks.[28]

Synthesis and production

In 1993, approximately 5,000–6,000 t of taurine was produced; 50% for pet food manufacture, 50% in pharmaceutical applications.[29] Synthetic taurine is obtained from isethionic acid (2-hydroxyethanesulfonic acid), which in turn is obtained from the reaction of ethylene oxide with aqueous sodium bisulfite.[30] Another approach is the reaction of aziridine with sulfurous acid. This leads directly to taurine.[citation needed]

As a functional food

Taurine is used as a functional food in many energy drinks and energy products[31] (and more recently, in a chocolate bar[32]).

Energy Drink (Incomprehensive List) Taurine concentration Normalized concentration
AMP 08.0fl oz - 0.0 servings - 0010mg - 010mg/8 fl oz 004.2 mg/100 ml4.2 mg/100 ml
Full Throttle 16fl oz - 2.0 servings - 1194mg1194 mg/16 fl oz (2 servings) 252 mg/100 ml
Go Girl 12fl oz - 1.0 servings - 1200mg1200 mg/12 fl oz (1 serving) 338 mg/100 ml
Jet*Set 10.5fl oz - 1.0 servings - 1000mg1000 mg/10.5 fl oz (1 serving) 322 mg/100 ml
Jolt Cola 23.5fl oz - 0.0 servings - 2800mg2800 mg/23.5 fl oz 403 mg/100 ml
Monster 08.0fl oz - 1.0 servings - 1000mg1000 mg/8 fl oz (1 serving) 423 mg/100 ml
NOS 08.0fl oz - 1.0 servings - 1000mg1000 mg/8 fl oz (1 serving) 423 mg/100 ml
Red Bull 08.3fl oz - 1.0 servings - 1000mg1000 mg/8.3 fl oz (1 serving) 408 mg/100 ml
Relentless 16fl oz - 2.0 servings - 2000mg2000 mg/16 fl oz (2 servings) 423 mg/100 ml
Rip It 08.0fl oz - 2.0 servings - 1000mg1000 mg/8 fl oz (2 serving) 423 mg/100 ml
Rockstar 16fl oz - 2.0 servings - 2000mg2000 mg/16 fl oz (2 servings) 423 mg/100 ml
SoBe Adrenaline Rush 16fl oz - 2.0 servings - 0960mg960 mg/16 fl oz (2 servings) 203 mg/100 ml
Starbucks Doubleshot 15fl oz - 2.0 servings - 1800mg1800 mg/15 fl oz (2 servings) 406 mg/100 ml
V 08.0fl oz - 0.0 servings - 0420mg420 mg/8 fl oz 178 mg/100 ml
Vitamin Energy 16fl oz - 0.0 servings - 2000mg2000 mg/16 fl oz 423 mg/100 ml
Vitamin Water Power C Dragon Fruit Flavor 20fl oz - 2.5 servings - 0025mg25 mg/20 fl oz (2.5 servings) 004.2 mg/100 ml4.2 mg/100 ml
Von Dutch 16fl oz - 2.0 servings - 2000mg2000 mg/16 fl oz (2 servings) 423 mg/100 ml


Energy Food (Incomprehensive List) Taurine concentration Normalized concentration
Snickers Charged   ( 1.83oz 51.0g ) 250mg/1.83 oz 137 mg/1 oz
0.00490 mg/mg

Despite being present in many energy foods, it has not been proven to be energy-giving. A study of mice hereditarily unable to transport taurine suggests that it is needed for proper maintenance and functioning of skeletal muscles.[33]

However, it has been proven effective in removing fatty liver deposits in humans, liver disease, and reducing cirrhosis in the rat.[34][35]

References

  1. ^ Bouckenooghe T, Remacle C, Reusens B (2006). "Is taurine a functional nutrient?". Curr Opin Clin Nutr. 9 (6): 728–733.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  2. ^ Brosnan J, Brosnan M (2006). "The sulfur-containing amino acids: an overview". J Nutr. 136 (6 Suppl): 1636S–1640S. PMID 16702333.
  3. ^ F. Tiedemann, L. Gmelin (1827). "Einige neue Bestandtheile der Galle des Ochsen". Annalen der Physik. 85 (2): 326–337. doi:10.1002/andp.18270850214.
  4. ^ Stapleton, PP (1998). "Host defense--a role for the amino acid taurine?". Journal of Parenteral and Enteral Nutrition. 22 (1): 42–48. doi:10.1177/014860719802200142. PMID 9437654. Retrieved 2006-08-19. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  5. ^ Weiss, Stephen J. (1982). "Chlorination of Taurine by Human Neutrophils". Journal of Clinical Investigation. 70 (3): 598–607. doi:10.1172/JCI110652. PMID 6286728. Retrieved 2006-08-19. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  6. ^ Kirk, Kiaran (1993). "Volume-regulatory taurine release from a human heart cancer cell line". FEBS Letters. 336 (1): 153–158. doi:10.1016/0014-5793(93)81630-I. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  7. ^ Carey, Francis A. (2006) [1987]. Organic Chemistry (6th ed. ed.). New York: McGraw Hill. p. 1149. ISBN 0-07-282837-4. Amino acids are carboxylic acids that contain an amine function. {{cite book}}: |edition= has extra text (help)
  8. ^ Lahdesmaki, P (1987). "Biosynthesis of taurine peptides in brain cytoplasmic fraction in vitro". Int J Neuroscience. 37 (1–2): 79–84. doi:10.3109/00207458708991804.
  9. ^ Redbullusa.com
  10. ^ Olive MF. Interactions between taurine and ethanol in the central nervous system. Amino Acids 2002;23(4):345-57
  11. ^ Antioxidant role and subcellular location of hypotaurine and taurine in human neutrophils. Green TR, Fellman JH, Eicher AL, Pratt KL. Biochimica et biophysica acta. 1991 Jan 23;1073(1):91-7.
  12. ^ Militante, J. D. (2002). "Treatment of hypertension with oral taurine: exp0/en.2005-1007". PMID 16627576. Retrieved 2006-08-22. {{cite journal}}: Cite journal requires |journal= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)
  13. ^ Li F, Abatan OI, Kim H, Burnett D, Larkin D, Obrosova IG, Stevens MJ (2006 Jun). "Taurine reverses neurological and neurovascular deficits in Zucker diabetic fatty rats". Neurobiology of Disease. 22 (3): 669–676. doi:10.1016/j.nbd.2006.01.012. PMID 16624563. {{cite journal}}: Check date values in: |year= (help)CS1 maint: multiple names: authors list (link)
  14. ^ Pop-Busui R, Sullivan KA, Van Huysen C, Bayer L, Cao X, Towns R, Stevens MJ (2001 Apr). "Depletion of taurine in experimental diabetic neuropathy: implications for nerve metabolic, vascular, and functional deficits". Exp Neurol. 168 (2): 259–272. doi:10.1006/exnr.2000.7591. PMID 11259114. {{cite journal}}: Check date values in: |year= (help)CS1 maint: multiple names: authors list (link)
  15. ^ Laidlaw S, Shultz T, Cecchino J, Kopple J (1988) "Plasma and urine taurine levels in vegans." American Journal of Clinical Nutrition, vol. 47, pp. 660-663.
  16. ^ Kong WX, Chen SW, Li YL; et al. (2006). "Effects of taurine on rat behaviors in three anxiety models". Pharmacol. Biochem. Behav. 83 (2): 271–6. doi:10.1016/j.pbb.2006.02.007. PMID 16540157. {{cite journal}}: Explicit use of et al. in: |author= (help)CS1 maint: multiple names: authors list (link)
  17. ^ Taurine induces anti-anxiety by activating strychnine-sensitive glycine receptor in vivo. Zhang CG, Kim SJ. Annals of Nutrition & Metabolism 2007;51(4):379-86. Epub 2007 Aug 29.
  18. ^ U. Warskulat, U. Flogel, C. Jacoby, H.-G. Hartwig, M. Thewissen, M. W. Merx, A. Molojavyi, B. Heller-Stilb, J. Schrader and D. Haussinger (2004). "Taurine transporter knockout depletes muscle taurine levels and results in severe skeletal muscle impairment but leaves cardiac function uncompromised". Faseb J.: 03–0496fje. doi:10.1096/fj.03-0496fje. PMID 14734644.{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: unflagged free DOI (link)
  19. ^ James, TJ (2004-04-01). "Ocular Health and Next Generation Solutions". Optometric Management. Retrieved 2008-01-10. {{cite web}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  20. ^ Yutaka Nakaya, Asako Minami, Nagakatsu Harada, Sadaichi Sakamoto, Yasuharu Niwa and Masaharu Ohnaka (January 2000). "Taurine improves insulin sensitivity in the Otsuka Long-Evans Tokushima Fatty rat, a model of spontaneous type 2 diabetes". American Journal of Clinical Nutrition. 71 (1): 54–58. PMID 10617946.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  21. ^ Effect of taurine treatment on insulin secretion and action, and on serum lipid levels in overweight men with a genetic predisposition for type II diabetes mellitus. C. Brøns, C. Spohr, H. Storgaard, J. Dyerberg, A. Vaag. European Journal of Clinical Nutrition (2004) 58, 1239–1247.
  22. ^ Taurine prevents high-glucose-induced human vascular endothelial cell apoptosis. Wu QD, Wang JH, Fennessy F, Redmond HP, Bouchier-Hayes D. The American journal of physiology. 1999 Dec;277(6 Pt 1):C1229-38.
  23. ^ Taurine prevents apoptosis induced by high ambient glucose in human tubule renal cells. Verzola D, Bertolotto MB, Villaggio B, Ottonello L, Dallegri F, Frumento G, Berruti V, Gandolfo MT, Garibotto G, Deferran G. Journal of investigative medicine: the official publication of the American Federation for Clinical Research. 2002 Nov;50(6):443-51.
  24. ^ Treatment of hypertension with oral taurine: experimental and clinical studies. Militante JD, Lombardini JB. Amino acids. 2002;23(4):381-93.
  25. ^ "Taurine And Its Importance In Cat Foods". Iams Cat Nutrition Library. 2004. Retrieved 2006-08-22.
  26. ^ "Nutrient Requirements of Cats". Nutrient Requirements of Cats, Revised Edition, 1986. 1986. Retrieved 2006-09-10.
  27. ^ AAFCO
  28. ^ Arnold, K.E. (2007). "Parental prey selection affects risk-taking behaviour and spatial learning in avian offspring" (PDF). Proceedings of the Royal Society B: Biological Sciences. 274 (1625): 2563–2569. doi:10.1098/rspb.2007.0687. Retrieved 2008-03-26. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  29. ^ Tully, Paul S. Sulfonic Acids. In Kirk-Othmer Encyclopedia of Chemical Technology. John Wiley & Sons, Inc. Published online 2000. doi:10.1002/0471238961.1921120620211212.a01
  30. ^ Kurt Kosswig. Sulfonic Acids, Aliphatic. in Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH, 2000. doi:10.1002/14356007.a25_503
  31. ^ This Ain't No Wine Cooler, John Cloud, Time Magazine, July 17, 2008
  32. ^ Boniface, Dan (2008-01-23). "New candy bar offers more than just a sugar high". 9news.com. Retrieved 2008-01-24.
  33. ^ U. Warskulat, U. Flogel, C. Jacoby, H.-G. Hartwig, M. Thewissen, M. W. Merx, A. Molojavyi, B. Heller-Stilb, J. Schrader and D. Haussinger (2004). "Taurine transporter knockout depletes muscle taurine levels and results in severe skeletal muscle impairment but leaves cardiac function uncompromised". Faseb J.: 03–0496fje. doi:10.1096/fj.03-0496fje. PMID 14734644.{{cite journal}}: CS1 maint: multiple names: authors list (link) CS1 maint: unflagged free DOI (link)
  34. ^ M. D. J. Kerai, Catherine J. Waterfield, S. H. Kenyon, D. S. Asker, J. A. Timbrell Taurine: Protective properties against ethanol-induced hepatic steatosis and lipid peroxidation during chronic ethanol consumption in rats Amino Acids Volume 15, Numbers 1-2 / March, 1998
  35. ^ McCall, Becky (2005-12-28). "The ultimate hangover cure?". bbc.co.uk. Retrieved 2008-09-01.

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