5-Hydroxytryptophan

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5-Hydroxytryptophan
IUPAC name 2-amino-3- (5-hydroxy-1H-indol-3-yl) propanoic acid
Identifiers
CAS number [56-69-9]
PubChem 144
MeSH 5-Hydroxytryptophan
SMILES
 
Properties
Molecular formula C11H12N2O3
Molar mass 220.225
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox disclaimer and references

5-Hydroxytryptophan or 5-HTP 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.

Contents

Metabolism

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.[1]

This reaction occurs both in nervous tissue and in the liver.[2] 5-HTP crosses the blood-brain barrier, while 5-HT does not. Excess 5-HTP, especially when administered with Vitamin B6, is thought to be metabolized and excreted.[3][4]

Pharmacology

The psychoactive action of 5-HTP is thought to derive from its effect on serotonin synthesis in central nervous system tissue. It is believed that an artificially high supply of 5-HTP causes the brain's serotonin-producing neurons to increase production. Increased serotonin production then leads to increased serotonin release.

Research shows that co-administration with carbidopa greatly increases plasma 5-HTP levels.[5] However, several studies have reported that 5-HTP is effective even without a PDI.[6][7] Other studies have indicated the risk of a scleroderma-like condition resulting from the combination of 5-HTP and carbidopa.[8]

5-HTP as therapeutic supplement

5-HTP, which is found in minute amounts in certain foods like turkey and cheesecitation needed, 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.

Research

Metabolic pathway from tryptophan to serotonin.
Metabolic pathway from tryptophan to serotonin.

5-HTP has been shown to be as effective as Imipramine for the treatment of depression. [9]

Current research shows promise in using 5-HTP for treating children with night terrors. After six months of use 83.9% of the children treated with 5-HTP were free from their persistent sleep terrors. [10]

Some persons with fibromyalgia find that 5-HTP improves their symptoms.[11] Fibromyalgia sufferers report improvement in sleep, depression, pain and all major complaints related to fibromyalgia.[12] Studies are continuing to refine dosage and continued use.

It is also used as a prophylactic against chronic daily headache. [13] 5-HTP may also be useful in treatment for migraines, since studies have shown that migraines occur when serotonin levels are low.

5-HTP has been shown to be an effective appetite suppressant. <Cn>

Dosage

Most supplement providers recommend 50 mg or 100 mg 5-HTP, one to three times per day. Most clinical studies have tested doses of 200-300 mg/day, although one study tested doses as large as 3250 mg/day. In some clinical studies 5-HTP is administered with carbidopa, which substantially changes 5-HTP's pharmacology.[14] Consumption with other proteins or amino acids will decrease absorption in the digestive tract. [15]

Serotonin syndrome was not observed in several studies that augmented traditional antidepressant therapy with 5-HTP, even though the combination therapy was expected to increase the risk of serotonin syndrome above 5-HTP alone.[15] Some users report high doses (300 mg and over) can produce nausea and vomiting.[16] High doses may be damaging to the liver.

See also

References

  1. ^ 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. 
  2. ^ 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
  3. ^ 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. 
  4. ^ 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. 
  5. ^ 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. 
  6. ^ Birdsall TC (1998). "5-Hydroxytryptophan: a clinically-effective serotonin precursor". Alternative medicine review : a journal of clinical therapeutic 3 (4): 271–80. PMID 9727088. 
  7. ^ VRP's Articel on 5-HTP Safety
  8. ^ 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. 
  9. ^ Altern Med Rev. 2000 Feb; 5(1), 64-71 Use of neurotransmitter precursors for treatment of depression., Meyers S.
  10. ^ Eur J Pediatr. 2004 Jul;163(7):402-7. Epub 2004 May 14. L -5-Hydroxytryptophan treatment of sleep terrors in children, Bruni O, Ferri R, Miano S, Verrillo E.
  11. ^ J Int Med Res. 1992 Apr;20(2):182-9 Primary fibromyalgia syndrome and 5-hydroxy-L-tryptophan: a 90-day open study., Sarzi Puttini P, Caruso I.
  12. ^ J Int Med Res. 1990 May-Jun;18(3):201-9. Double-blind study of 5-hydroxytryptophan versus placebo in the treatment of primary fibromyalgia syndrome., Caruso I, Sarzi Puttini P, Cazzola M, Azzolini V.
  13. ^ 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. 
  14. ^ Magnussen I, Van Woert MH (1982). "Human pharmacokinetics of long term 5-hydroxytryptophan combined with decarboxylase inhibitors". Eur. J. Clin. Pharmacol. 23 (1): 81–6. doi:10.1007/BF01061381. PMID 6182005. 
  15. ^ a b Turner EH, Loftis JM, Blackwell AD (2006). "Serotonin a la carte: supplementation with the serotonin precursor 5-hydroxytryptophan". Pharmacol. Ther. 109 (3): 325–38. doi:10.1016/j.pharmthera.2005.06.004. PMID 16023217. 
  16. ^ "Erowid Experience Vaults: Search Results". Retrieved on 2007-06-09.

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. 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. 
v • d • e
Neurotransmitter metabolic intermediates
tyrosine→dopamine→epinephrine
Catecholamine metabolites
tryptophan→serotonin
anabolism: 5-Hydroxytryptophan
catabolism: 5-Hydroxyindoleacetic acid
serotonin→melatonin
see also enzymes

Wikipedia content modification information:

  • This page was last modified on 6 July 2008, at 13:14.

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