5-Hydroxytryptophan.html |
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| 5-Hydroxytryptophan | |
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| IUPAC name | 2-amino-3- (5-hydroxy-1H-indol-3-yl) propanoic acid |
| Identifiers | |
| CAS number | 56-69-9 |
| PubChem | |
| MeSH | |
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| ChemSpider ID | |
| 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 references |
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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, however insufficient high quality research has been done to establish that it is efficacious.1
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 B6.2
This reaction occurs both in nervous tissue and in the liver.3 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.45
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.6 However, several studies have reported that 5-HTP is effective even without a peripheral decarboxylase inhibitor (e.g. carbidopa).78 Other studies have indicated the risk of a scleroderma-like condition resulting from the combination of 5-HTP and carbidopa.9
As a therapeutic supplement
5-HTP, which is found in minute amounts in certain foods like cheese and the white meat of poultry,citation 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
A recent (2002) 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 note that overall "the evidence was of insufficient quality to be conclusive." Furthermore, "... 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."10
Possible risks or side effects
Because 5-HTP has not been throughly studied in a clinical setting, possible side effects and interactions with other drugs are not well known.
Direct and indirect evidence for possible risks and side effects associated with 5-HTP:
In animals:
- In rodents, 5-HTP administration is used in various experimental procedures to induce a "head twitch response" -- behaviour generally thought to be correlated with the animal experiencing hallucinations.11 12 There is no evidence however for a similar response in humans, at least when dosage is within the recommended daily levels.
- In rats, 5-HTP administration raises the risk of serotonin toxicity when given alongside other serotonergic drugs.13.
- When given to pregnant sheep, 5-HTP alters the behavior of the fetus.14
In people:
- When combined with carbidopa (as a treatment for symptoms of Parkinson's disease), 5-HTP causes nausea and vomiting; however this can be alleviated via administration of granisetron.15
- Taken with party pills, 5-HTP administration may raise the risk of acute serotonin syndrome.16
See also
- Serotonin
- Tryptophan
- Vitamin B6
- Pyridoxal Phosphate (PLP) - Bioactive form of vitamin B6
References
- ^ Shaw K, Turner J, Del Mar C (2001). "Tryptophan and 5-hydroxytryptophan for depression". Cochrane Database Syst Rev (3): CD003198. doi:. PMID 11687048.
- ^ 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:. PMID 6983619.
- ^ 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
- ^ 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.
- ^ 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.
- ^ 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.
- ^ Birdsall TC (1998). "5-Hydroxytryptophan: a clinically-effective serotonin precursor". Alternative medicine review : a journal of clinical therapeutic 3 (4): 271–80. PMID 9727088.
- ^ VRP's Article on 5-HTP Safety
- ^ 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.
- ^ Shaw K, Turner J, Del Mar C (2001). "Tryptophan and 5-hydroxytryptophan for depression". Cochrane Database Syst Rev (3): CD003198. doi:. PMID 11687048.
- ^ May JA, Dantanarayana AP, Zinke PW, McLaughlin MA, Sharif NA (Jan 2006). "1-((S)-2-aminopropyl)-1H-indazol-6-ol: a potent peripherally acting 5-HT2 receptor agonist with ocular hypotensive activity". Journal of medicinal chemistry 49 (1): 318–28. doi:. PMID 16392816.
- ^ Pandey DK, Rajkumar R, Mahesh R, Radha R (Dec 2008). "Depressant-like effects of parthenolide in a rodent behavioural antidepressant test battery". J Pharm Pharmacol. 60 (12): 1643–50. doi:. PMID 19000369.
- ^ Pandey DK, Rajkumar R, Mahesh R, Radha R (Dec 2008). "Depressant-like effects of parthenolide in a rodent behavioural antidepressant test battery". J Pharm Pharmacol. 60 (12): 1643–50. doi:. PMID 19000369.
- ^ Morrison JL, Chien C, Gruber N, Rurak D, Riggs W (Nov 2001). "Fetal behavioural state changes following maternal fluoxetine infusion in sheep". Brain Res Dev Brain Res. 131 (1-2): 47–56. PMID 11718835, http://linkinghub.elsevier.com/retrieve/pii/S0165380601002553.
- ^ 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:. PMID 18719048.
- ^ Wilkins C, Sweetsur P, Girling M (Mar 2008). "Patterns of benzylpiperazine/trifluoromethylphenylpiperazine party pill use and adverse effects in a population sample in New Zealand". Drug Alcohol Rev: 1–7. doi:. PMID 18608458.
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.
- article at Psychology Today
- 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:. PMID 16023217.
- 5-Hydroxytryptophan (5-HTP) Supplement Information at University of Maryland Medical Center
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