5-Hydroxytryptophan

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5-hydroxytryptophan
5-Hydroxytryptophan
Molecular model of 5-hydroxytryptophan
Chemical name 5-hydroxytryptophan
5-HTP
(S)-2-amino-3-(5-hydroxy-1H-
indol-3-yl)propanoic acid
Chemical formula C11H12N2O3
Molecular mass 220.22458 g/mol
CAS number [56-69-9]
SMILES Oc1cc2c(C[C@@](N)([H])
C(O)=O)c[nH]c2cc1
Disclaimer and references

5-Hydroxytryptophan or 5-HTP is 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

[edit] Pharmacology

5-Hydroxytryptophan is decarboxylated to serotonin (5-hydroxytryptamine) by the enzyme aromatic-L-amino-acid decarboxylase.

The psychoactive action of 5-HTP is thought to derive from its effect on serotonin synthesis. 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.

Some doctors suggest that 5-HTP be administered with a peripheral decarboxylase inhibitor such as carbidopa in order to prevent elevated levels of serotonin in the bloodstream (and their side effects, which include emesis and potentially fibrosis of the heart).[1] Research shows that co-administration with carbidopa greatly increases plasma 5-HTP levels.[2]

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

[edit] 5-HTP as therapeutic supplement

5-HTP, which is found in infinitesimal amounts in certain foods like turkey and cheese, is often sold as an over-the-counter therapeutic supplement. In this case, it is usually sourced from the seeds of the Griffonia simplicifolia plant. Production of 5-HTP as a supplement increased when a similar serotonin-altering supplement. 5-HTP has many advantages over L-tryptophan: being safer to produce and arguably more potent. 5-HTP in supplement form is usually sold in gelatin capsules. These capsules typically contain either 50mg or 100mg of 5-HTP per capsule. It is recommended to take it on an empty stomach before falling asleep, or in smaller doses throughout the day.

[edit] Research

It has been alleged that 5-HTP can be used to treat mental disorders such as depression. Unfortunately, the studies to date are incomplete. Reviews of these studies do indicate that potential exists for 5-HTP in the treatment of depression, but further trials are stressed as necessary before arriving at any firm conclusion.[3] Some caution and diligence should be exhibited regarding 5-HTP barring further study and review.

Reductions in serotonergic tone are partially responsible for cognitive deficits (memory loss) resulting from tetrahydrocannibinol (THC, the active component in marijuana). When given to rats, 5-HTP can significantly attenuate THC-induced memory impairment.[4]

[edit] Uses

In recent years 5-HTP has been sold by health food companies as an alternative treatment for depression and mood disorders. Its role as an intermediary in the biosynthesis of serotonin indicates that this chemical may indeed be effective in treating these and other serotonin-related disorders, but there is some debate on the conclusions of the clinical trials which have been carried out using the drug.[citation needed]

5-HTP is also used as a supplement by users of MDMA (ecstasy) to help replenish depleted serotonin, in an attempt to alleviate to a degree the depression and overall mental unsettlement that sometimes occurs in the days following MDMA usage. It should be noted that a temporary decline in serotonin levels is only one of several factors in post-MDMA use cognitive disruptions; neuroadaptive changes in receptor density likely play a larger long-term role.[4] 5-HTP is less commonly used immediately before the use of MDMA as a means to both further reduce the negative psychological effects of depleted serotonin, and as an attempt to boost the effects of MDMA. Anecdotal reports seem to indicate this is largely placebo with some users reporting a moderate muting of the MDMA effect.[5]

[edit] Dosage

Though there is no official dosage, most supplement providers recommend 50 mg or 100 mg 5-HTP, one to three times per day.[citation needed] Most clinical studies have tested doses of 200-300 mg/day, although one study tested doses as large as 3250 mg/day. Although many studies do not report a dosing schedule, the majority of those that do have reported using two to four doses split throughout the day.[6]

In theory, an overdose of 5-HTP could cause serotonin syndrome. However, serotonin syndrome was not observed in several studies that augmented traditional antidepressant therapy with 5-HTP, even though the combination therapy was expected increase the risk of serotonin syndrome above 5-HTP alone.[6] In dogs, doses of 23.6 mg/kg were found to cause toxic reactions, although the dose response curve for dogs does not necessarily scale to humans.[7] Some users report high doses (300 mg and over) can produce nausea and vomiting.[8]

[edit] Side effects

Promoters of 5-HTP claim that it causes fewer side effects than traditional antidepressants. Side effects of 5-HTP may include nausea, constipation, gas, drowsiness, or a decreased sex drive. It can also have adverse interactions with other natural and traditional drugs.[9] Others warn that the long term effects of 5-HTP are not known, and point out that people using any psychiatric drug, natural or otherwise, should be under a doctor's supervision. [10]

[edit] See also


[edit] References

  1. ^ Usenet post by Steven B. Harris: "5-HTP + B6 = Trouble; Doc Harris Presents Green Banana Award"
  2. ^ Magnussen I. et al. (1981): "Plasma accumulation of metabolism of orally administered single dose L-5-hydroxytryptophan in man.", Acta Pharmacol. Toxicol. (Copenh), Vol. 49(3), 184-9 PMID 6175178
  3. ^ Meyers S 2000 Feb "Use of neurotransmitter precursors for treatment of depression". Altern Med Rev 5(1), 64-71, PMID 10696120
  4. ^ Eur J Pharmacol. 2002 Jun 12;445(3):221-9. Involvement of 5-hydroxytryptamine neuronal system in Delta(9)-tetrahydrocannabinol-induced impairment of spatial memory. Egashira N, Mishima K, Katsurabayashi S, Yoshitake T, Matsumoto Y, Ishida J, Yamaguchi M, Iwasaki K, Fujiwara M. PMID 12079687
  5. ^ MDMA and 5-HTP information and advice
  6. ^ a b PMID 16023217
  7. ^ PMID 10863592
  8. ^ [1]
  9. ^ [2]
  10. ^ [3]
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