5-Hydroxytryptophan: Wikis


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CAS number 56-69-9 Yes check.svgY
PubChem 144
ChemSpider 388413
MeSH 5-Hydroxytryptophan
Molecular formula C11H12N2O3
Molar mass 220.23 g/mol
 Yes check.svgY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

5-Hydroxytryptophan (5-HTP; Oxitriptan) is a naturally occurring amino acid, a precursor to the neurotransmitter serotonin and an intermediate in tryptophan metabolism. It is marketed in the United States and other countries as a dietary supplement for use as an antidepressant, appetite suppressant, and sleep aid. According to a 2001 meta-analysis, no sufficient high quality research had, at that point, been done to establish its effectiveness for treatment of clinical depression or dysthymia.[1]



5-HTP AAAD Serotonin
5-hydroxytryptophan.png   Serotonin-skeletal.png
Biochem reaction arrow foward YNNN horiz med.png

5-Hydroxytryptophan is decarboxylated to serotonin (5-hydroxytryptamine or 5-HT) by the enzyme aromatic-L-amino-acid decarboxylase with the help of Vitamin B6.[2]

This reaction occurs both in nervous tissue and in the liver.[3] 5-HTP crosses the blood-brain barrier [4], while 5-HT does not. Excess 5-HTP, especially when administered with Vitamin B6, is thought to be metabolized and excreted.[5][6]


The psychoactive action of 5-HTP is derived from its effect on the production of serotonin in central nervous system tissue. More specifically, 5-HTP increases the production of serotonin.[7] Thus, it has been used to treat diseases, e.g. depression, for which the lack of serotonin is thought to be a contributing factor.[8]

Research shows that co-administration with carbidopa greatly increases plasma 5-HTP levels.[9] However, several studies have reported that 5-HTP is effective even without a peripheral decarboxylase inhibitor (e.g. carbidopa).[10] Other studies have indicated the risk of a scleroderma-like condition resulting from the combination of 5-HTP and carbidopa.[11]

As a therapeutic supplement

Though 5-HTP is not found in food in any significant quantities, it is a chemical involved intermediately in the metabolism of tryptophan, an amino acid found in turkey, milk, potatoes, pumpkin, and various greens.[12] It is often sold as an over-the-counter therapeutic supplement. In this case, it is usually sourced from the seeds of Griffonia simplicifolia. 5-HTP in supplement form is typically sold in 50 mg or 100 mg gelatin or vegetarian capsules.

5-HTP has been known to be used as a remedy to counter the withdrawal symptoms that can occur after taking MDMA (commonly known as Ecstasy), a drug known for depleting the serotonin in the brain. Many users report that taking 5-HTP after Ecstasy use reduces its negative side-effects, including depression, that they experience in the days after.[13]


5-HTP has been studied and shown to be of benefit in the following conditions: primary fibromyalgia syndrome,[14] Friedreich's ataxia,[15] LSD-induced psychosis,[16] chronic headaches (primary or otherwise),[17] depression, anxiety, binge eating associated with obesity, and insomnia.[18]

A 2001 meta-analysis found that of 108 studies on 5-HTP published between 1966 and 2000, only two met the authors' quality standards for inclusion. The two studies that were deemed of sufficient quality did not deal with 5-HTP exclusively, instead combining results for 5-HTP and tryptophan, so the results may not be completely applicable for 5-HTP alone. While the combined analysis of the two 5-HTP and tryptophan studies showed significant effectiveness over placebo in treating depression, the authors state that overall "the evidence was of insufficient quality to be conclusive." They also state that "because alternative antidepressants exist which have been proven to be effective and safe, the clinical usefulness of 5-HTP and tryptophan is limited at present."[1]

Metabolic pathway from tryptophan to serotonin.

Possible risks or side effects

Because 5-HTP has not been thoroughly studied in a clinical setting, possible side effects and interactions with other drugs are not well known.

Administered serotonin, though not 5-HTP itself, has been shown to increase the risk of heart valve disease in animals.[19][20]

5-HTP can cause hypertension by increasing plasma renin activity, when not co-administered with a peripheral aromatic L-amino acid decarboxylase inhibitor, such as carbidopa or benserazide [21].

Direct and indirect evidence for possible yet unproven risks and side effects associated with 5-HTP when overdosed:

See also


  1. ^ a b Shaw K, Turner J, Del Mar C (2001). "Tryptophan and 5-hydroxytryptophan for depression". Cochrane Database Syst Rev (3): CD003198. doi:10.1002/14651858.CD003198. PMID 11687048. 
  2. ^ Rahman MK, Nagatsu T, Sakurai T, Hori S, Abe M, Matsuda M (1982). "Effect of pyridoxal phosphate deficiency on aromatic L-amino acid decarboxylase activity with L-DOPA and L-5-hydroxytryptophan as substrates in rats". Jpn. J. Pharmacol. 32 (5): 803–11. doi:10.1254/jjp.32.803. PMID 6983619. 
  3. ^ Bouchard S, Bousquet C, Roberge AG. Characteristics of dihydroxyphenylalanine/5-hydroxytryptophan decarboxylase activity in brain and liver of cat. J Neurochem. 1981 Sep;37(3):781-7. PMID 6974228
  4. ^ Gomes P, Soares-da-Silva P. (1999). "L-DOPA transport properties in an immortalised cell line of rat capillary cerebral endothelial cells, RBE 4.". Brain Res. 829 (1-2): 143–150. doi:10.1016/S0006-8993(99)01387-6. PMID 18445233. 
  5. ^ Bouchard S, Roberge AG (1979). "Biochemical properties and kinetic parameters of dihydroxyphenylalanine--5-hydroxytryptophan decarboxylase in brain, liver, and adrenals of cat". Can. J. Biochem. 57 (7): 1014–8. PMID 39668. 
  6. ^ Amamoto T, Sarai K (1976). "On the tryptophan-serotonin metabolism in manic-depressive disorders. Changes in plasma 5-HT and 5-HIAA levels and urinary 5-HIAA excretion following oral loading of L-5HTP in patients with depression". Hiroshima J. Med. Sci. 25 (2-3): 135–40. PMID 1088369. 
  7. ^ "5-HTP: Uses, Side Effects, Interactions and Warnings - WebMD". http://www.webmd.com/vitamins-supplements/ingredientmono-794-5-HTP.aspx?activeIngredientId=794&activeIngredientName=5-HTP. Retrieved 2009-10-05. 
  8. ^ "Health.com: 5-hydroxytryptophan : Information on Uses, Dosage & Side Effects on Health.com". http://tools.health.com/natstandardcontent/5-htp-1#H7. Retrieved 2009-10-05. 
  9. ^ Magnussen I, Jensen TS, Rand JH, Van Woert MH (1981). "Plasma accumulation of metabolism of orally administered single dose L-5-hydroxytryptophan in man". Acta pharmacologica et toxicologica 49 (3): 184–9. PMID 6175178. 
  10. ^ Birdsall TC (1998). "5-Hydroxytryptophan: a clinically-effective serotonin precursor". Alternative medicine review : a journal of clinical therapeutic 3 (4): 271–80. PMID 9727088. 
  11. ^ Sternberg EM, Van Woert MH, Young SN, et al. (1980). "Development of a scleroderma-like illness during therapy with L-5-hydroxytryptophan and carbidopa". N. Engl. J. Med. 303 (14): 782–7. PMID 6997735. 
  12. ^ "5-Hydroxytryptophan". http://www.umm.edu/altmed/articles/5-hydroxytryptophan-000283.htm. Retrieved 2010-01-21. 
  13. ^ "Drug Info". http://www.dancesafe.org/documents/druginfo/depression.php#5htp. Retrieved 2009-10-05. 
  14. ^ Caruso I, Sarzi Puttini P, Cazzola M, Azzolini V (1990). "Double-blind study of 5-hydroxytryptophan versus placebo in the treatment of primary fibromyalgia syndrome". The Journal of International Medical Research 18 (3): 201–9. PMID 2193835. 
  15. ^ Trouillas P, Serratrice G, Laplane D, et al. (May 1995). "Levorotatory form of 5-hydroxytryptophan in Friedreich's ataxia. Results of a double-blind drug-placebo cooperative study". Archives of Neurology 52 (5): 456–60. PMID 7733839. http://archneur.ama-assn.org/cgi/pmidlookup?view=long&pmid=7733839. Retrieved 2009-07-30. 
  16. ^ Abraham HD (April 1983). "L-5-hydroxytryptophan for LSD-induced psychosis". The American Journal of Psychiatry 140 (4): 456–8. PMID 6601463. http://ajp.psychiatryonline.org/cgi/pmidlookup?view=long&pmid=6601463. Retrieved 2009-07-30. 
  17. ^ De Benedittis G, Massei R (1985). "Serotonin precursors in chronic primary headache. A double-blind cross-over study with L-5-hydroxytryptophan vs. placebo". Journal of Neurosurgical Sciences 29 (3): 239–48. PMID 3913752. 
  18. ^ Birdsall TC (August 1998). "5-Hydroxytryptophan: a clinically-effective serotonin precursor". Alternative Medicine Review : a Journal of Clinical Therapeutic 3 (4): 271–80. PMID 9727088. http://www.thorne.com/altmedrev/.fulltext/3/4/271.pdf. Retrieved 2009-07-30. 
  19. ^ a b Gustafsson BI, Tømmerås K, Nordrum I, Loennechen JP, Brunsvik A, Solligård E, Fossmark R, Bakke I, Syversen U, Waldum H (March 2005). "Long-term serotonin administration induces heart valve disease in rats". Circulation 111 (12): 1517–22. doi:10.1161/01.CIR.0000159356.42064.48. PMID 15781732. 
  20. ^ a b Xu J, Jian B, Chu R, Lu Z, Li Q, Dunlop J, Rosenzweig-Lipson S, McGonigle P, Levy RJ, Liang B (December 2002). "Serotonin mechanisms in heart valve disease II: the 5-HT2 receptor and its signaling pathway in aortic valve interstitial cells". Am. J. Pathol. 161 (6): 2209–18. PMID 12466135.& PMC 1850896. http://ajp.amjpathol.org/cgi/content/abstract/161/6/2209. 
  21. ^ Barney CC, Threatte RM, Kikta DC, Fregly MJ. (June 1981). "Effects of serotonin and L-5-hydroxytryptophan on plasma renin activity in rats.". Pharmacol Biochem Behav. 14 (6): 895–900. doi:10.1016/0091-3057(81)90380-4. PMID 7019933. 
  22. ^ Ma Z, Zhang G, Jenney C, Krishnamoorthy S, Tao R. (July 2008). "Characterization of serotonin-toxicity syndrome (toxidrome) elicited by 5-hydroxy-l-tryptophan in clorgyline-pretreated rats.". Eur J Pharmacol. 588 (2-3): 198–206. doi:10.1016/j.ejphar.2008.04.004. PMID 18499101. 
  23. ^ Izumi T, Iwamoto N, Kitaichi Y, Kato A, Inoue T, Koyama T. (2006). "Effects of co-administration of a selective serotonin reuptake inhibitor and monoamine oxidase inhibitors on 5-HT-related behavior in rats.". Eur J Pharmacol. 532 (3): 258–264. doi:10.1016/j.ejphar.2005.12.075. PMID 16488409. 
  24. ^ Jacobs G, Kamerling I, de Kam M, et al. (Nov 2008). "Enhanced tolerability of the 5-hydroxytryptophane challenge test combined with granisetron". J Psychopharmacol. (Oxford). doi:10.1177/0269881108094299. PMID 18719048. 

Further reading

  • den Boer JA, Westenberg HG (1990). "Behavioral, neuroendocrine, and biochemical effects of 5-hydroxytryptophan administration in panic disorder". Psychiatry research 31 (3): 267–78. doi:10.1016/0165-1781(90)90096-N. PMID 2139731. 
  • Angst J, Woggon B, Schoepf J (1977). "The treatment of depression with L-5-hydroxytryptophan versus imipramine. Results of two open and one double-blind study". Archiv für Psychiatrie und Nervenkrankheiten 224 (2): 175–86. PMID 336002. 
  • article at Psychology Today

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