5-Hydroxytryptophan

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5-Hydroxytryptophan
5-Hydroxy-L-Tryptophan (5-HTP).svg
5-Hydroxy-L-tryptophan-3D-balls.png
Names
IUPAC name
2-amino-3-(5-hydroxy-1H-indol-3-yl)propanoic acid
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.022.193 OOjs UI icon edit-ltr-progressive.svg
KEGG
MeSH 5-Hydroxytryptophan
PubChem CID
UNII
  • InChI=1S/C11H12N2O3/c12-9(11(15)16)3-6-5-13-10-2-1-7(14)4-8(6)10/h1-2,4-5,9,13-14H,3,12H2,(H,15,16)/t9-/m0/s1 Yes check.svgY
    Key: LDCYZAJDBXYCGN-VIFPVBQESA-N Yes check.svgY
  • InChI=1/C11H12N2O3/c12-9(11(15)16)3-6-5-13-10-2-1-7(14)4-8(6)10/h1-2,4-5,9,13-14H,3,12H2,(H,15,16)/t9-/m0/s1
    Key: LDCYZAJDBXYCGN-VIFPVBQEBZ
  • O=C(O)[C@@H](N)Cc2c1cc(O)ccc1[nH]c2
Properties
C11H12N2O3
Molar mass 220.228 g·mol−1
Density 1.484 g/mL
Melting point 298 to 300 °C (568 to 572 °F; 571 to 573 K)
Boiling point 520.6 °C (969.1 °F; 793.8 K)
Pharmacology
N06AX01 ( WHO )
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

5-Hydroxytryptophan (5-HTP), also known as oxitriptan, is a naturally occurring amino acid and chemical precursor as well as a metabolic intermediate in the biosynthesis of the neurotransmitter serotonin.

Uses

5-HTP is sold over the counter in the United States, France, Canada, Singapore, the Netherlands, and the United Kingdom as a dietary supplement for use as an antidepressant, appetite suppressant, and sleep aid. It is also marketed in many European countries for the indication of major depression under the trade names Cincofarm, Levothym, Levotonine, Oxyfan, Telesol, Tript-OH, and Triptum. [1]

A 2002 review concluded that although the data evaluated suggests that 5-HTP is more effective than placebo in the treatment of depression, the evidence was insufficient to be conclusive due to a lack of clinical data meeting the rigorous standards of the day. [2] More and larger studies using current methodologies are needed to determine if 5-HTP is truly effective in treating depression. [3] [4] In small, controlled trials 5-HTP has also been reported to augment the antidepressant efficacy of the antidepressant clomipramine. [5] [6] [7] A 2020 meta-analysis found oral 5-HTP supplementation had a large effect size on depression symptom severity. However, the included studies were considered relatively weak and the methods and treatment duration varied between the seven studies examined. [8]

5-HTP use after MDMA

MDMA is an empathogenic-entactogenic and serotonergic psychotropic drug used primarily for recreational, though sometimes also therapeutic, purposes. Among users of MDMA, the serotonergic effects of the drug are often of particular interest and concern: After consuming MDMA, serotonin concentrations are greatly reduced in the brain. 5-HTP is necessary for serotonin production and its concentrations in the brain also decrease after taking MDMA.

Other usage

At high doses, or in combination with carbidopa, 5-HTP has been used to treat obesity (by promoting weight loss). [9] [10]

In clinical trials of various design, 5-HTP has also been reported to treat fibromyalgia, [11] myoclonus, [12] migraine, [13] and cerebellar ataxia. [14] However, these clinical findings, as for all therapeutic findings with 5-HTP, are preliminary and need confirmation in larger trials.

Drawbacks

5-HTP's short half-life (<2h) [15] may inherently limit its therapeutic potential, [16] as systemic 5-HTP exposure levels will fluctuate substantially even with relatively frequent dosing. Such exposure fluctuations are usually associated with increased adverse event burdens resulting from Cmax (time to maximal systemic concentration) drug spikes, and decreased clinical efficacy resulting from sub-therapeutic exposure for large parts of the day, when taken as a single dose unit or at intervals significantly larger than Cmax. It has been proposed that 5-HTP dosage forms achieving prolonged delivery would be more effective, [16] as has been demonstrated many times with other pharmaceuticals with short durations of action. [17] For example, controlled release oxycodone (OxyContin) or morphine (MS-Contin) are intended to, via novel delivery mechanisms, permit pain relief for up to twelve hours with an active ingredient which only provides relief for 3–6 hours. However, the inherent variability amongst different people with respect to drug metabolism makes this task challenging.

Side effects

Potential side effects of 5-HTP include heartburn, stomach pain, nausea, vomiting, diarrhea, drowsiness, sexual problems, vivid dreams or nightmares, and muscle problems. [18] Because 5-HTP has not been thoroughly studied in a clinical setting, possible side effects and interactions with other drugs are not well known. According to the US National Library of Medicine, 5-HTP has not been associated with serotonin syndrome or any serious adverse events in humans. [19] Across multiple studies, 5-HTP has also been reported to not cause any noticeable hematological or cardiovascular changes. [20] 5-HTP had also been associated with eosinophilia, but later studies have not found any causal connection. [21]

Interactions

When combined with antidepressants of the MAOI or SSRI class, very high parenteral doses of 5-HTP can cause acute serotonin syndrome in rats. [22] [23] It is unclear if such findings have clinical relevance, as most drugs will cause serious adverse events or death in rodents at very high doses. In humans 5-HTP has never been clinically associated with serotonin syndrome, although a case report suggests 5-HTP can precipitate mania when added to an MAOI. [24]

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. [25] As mentioned below under pharmacology, cases of scleroderma-like illness have been reported in patients using carbidopa and 5-HTP. [26]

Oral 5-HTP results in an increase in urinary 5-HIAA, a serotonin metabolite, indicating that 5-HTP is peripherally metabolized to serotonin, which is then metabolized. This might cause false positive results in tests looking for carcinoid syndrome. [27] [28] Due to the conversion of 5-HTP into serotonin by the liver, there could be a risk of heart valve disease from serotonin's effect on the heart, as based on preclinical findings. [29] [30] However, 5-HTP has not been associated with cardiac toxicity in humans. [21] [20] [19] [31]

It has been suggested that 5-HTP may cause eosinophilia-myalgia syndrome (EMS), a serious condition which results in extreme muscle tenderness, myalgia, and blood abnormalities. However, there is evidence to show that EMS was likely caused by a contaminant in certain 5-HTP supplements. [32]

Production

5-HTP is produced from the amino acid tryptophan through the action of the enzyme tryptophan hydroxylase. Tryptophan hydroxylase is one of the biopterin-dependent aromatic amino acid hydroxylases. Production of 5-HTP is the rate-limiting step in 5-HT (serotonin) synthesis. 5-HTP is normally rapidly converted to 5-HT by amino acid decarboxylase. [33]

Absorption

After oral administration, 5-HTP is absorbed by the upper intestine. [15] The mode of absorption is not known, but presumably involves active transport via amino acid transporters. 5-HTP is adequately absorbed via oral cavity. [34] With a decarboxylase inhibitor, the bioavailability of 5-HTP can be higher than 50%. [35]

Pharmacokinetics

5-HTP is rapidly absorbed with a tmax of ≈1.5 h, and rapidly eliminated with a half-life of ≈1.5 – 2 h. Co-administration of a decarboxylase inhibitor (e.g. carbidopa, benserazide) doubles the half-life of 5-HTP to ≈ 3 – 4 h, [36] [15] and enhances exposure several-fold, depending on the dosing regimen. [15] [37]

Metabolism

5-HTP is decarboxylated to serotonin (5-hydroxytryptamine or 5-HT) by the enzyme aromatic-L-amino-acid decarboxylase with the help of vitamin B6. [38] This reaction occurs both in nervous tissue and in the liver. [39] 5-HTP crosses the blood–brain barrier, [40] while 5-HT does not. Excess 5-HTP, especially when administered with vitamin B6, is thought to be metabolized and excreted. [41] [42]

5-HTP AAAD Serotonin
5-Hydroxy-L-Tryptophan (5-HTP).svg   Serotonin (5-HT).svg
PLP
Biochem reaction arrow forward YNNN horiz med.svg
 
 

Pharmacology

The psychoactive action of 5-HTP is derived from its increase in production of serotonin in central nervous system tissue. [43]

Metabolic pathway from tryptophan to serotonin. Trp-5ht-pathway.svg
Metabolic pathway from tryptophan to serotonin.

Research shows that co-administration with carbidopa greatly increases plasma 5-HTP levels. [44] Other studies have indicated the risk of a scleroderma-like condition resulting from the combination of 5-HTP and carbidopa. [45]

Regulatory status

There are currently no approved drug products containing 5-HTP approved by the FDA. [46] All available 5-HTP products are nutraceuticals and are as such not regulated or verified for purity, integrity, or clinical efficacy or safety, mandating caution regarding human consumption. [47]

As of 25 August 2020, Hungary added 5-HTP to the controlled psychoactive substances list, prohibiting production, sale, import, storage and use, becoming the first country to do so. [48]

5-HTP slow-release

5-HTP's short half-life is impractical for chronic drug therapy. Research conducted at Duke University in mice have demonstrated that 5-HTP when administered as slow-release appears to gain drug properties. [49] Slow-release delivery attenuates or abolishes the peaks and valleys in 5-HTP exposure during treatment. [50] Slow-release delivery of 5-HTP markedly improved the safety profile of 5-HTP and conferred stable plasma exposure of 5-HTP and strong and sustained enhancement of brain serotonin function. [49] This discovery indicates that 5-HTP slow-release medications represent a new avenue for treatment of brain disorders responsive to serotonergic enhancement.

Dietary sources

Though 5-HTP is found in food only in insignificant quantities, it is a chemical involved intermediately in the metabolism of tryptophan, an amino acid found in all unfractionated foods, with lower total amino acid content correlating with increased tryptophan absorption. [51]

The seeds of the Griffonia simplicifolia , a climbing shrub native to West Africa and Central Africa, are used as an herbal supplement for their 5-HTP content. [52] [53] [54] In one 2010 trial, Griffonia simplicifolia extract appeared to increase satiety in overweight women. [55]

See also

Related Research Articles

<span class="mw-page-title-main">Serotonin</span> Monoamine neurotransmitter

Serotonin or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Its biological function is complex, touching on diverse functions including mood, cognition, reward, learning, memory, and numerous physiological processes such as vomiting and vasoconstriction.

<span class="mw-page-title-main">Serotonin syndrome</span> Symptoms caused by an excess of serotonin in the central nervous system

Serotonin syndrome (SS) is a group of symptoms that may occur with the use of certain serotonergic medications or drugs. The symptoms can range from mild to severe, and are potentially fatal. Symptoms in mild cases include high blood pressure and a fast heart rate; usually without a fever. Symptoms in moderate cases include high body temperature, agitation, increased reflexes, tremor, sweating, dilated pupils, and diarrhea. In severe cases, body temperature can increase to greater than 41.1 °C (106.0 °F). Complications may include seizures and extensive muscle breakdown.

<span class="mw-page-title-main">Tryptophan</span> Chemical compound

Tryptophan (symbol Trp or W) is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α-carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromatic beta carbon substituent. Tryptophan is also a precursor to the neurotransmitter serotonin, the hormone melatonin, and vitamin B3. It is encoded by the codon UGG.

<span class="mw-page-title-main">Mirtazapine</span> Antidepressant medication

Mirtazapine, sold under the brand name Remeron among others, is an atypical tetracyclic antidepressant, and as such is used primarily to treat depression. Its effects may take up to four weeks, but can also manifest as early as one to two weeks. It is often used in cases of depression complicated by anxiety or insomnia. The effectiveness of mirtazapine is comparable to other commonly prescribed antidepressants. It is taken by mouth.

<span class="mw-page-title-main">Ergotamine</span> Chemical compound in the ergot family of alkaloids

Ergotamine, sold under the brand names Cafergot and Ergomar among others, is an ergopeptine and part of the ergot family of alkaloids; it is structurally and biochemically closely related to ergoline. It is structurally similar to several neurotransmitters, and it acts as a vasoconstrictor.

Aromatic <small>L</small>-amino acid decarboxylase Class of enzymes

Aromatic L-amino acid decarboxylase, also known as DOPA decarboxylase (DDC), tryptophan decarboxylase, and 5-hydroxytryptophan decarboxylase, is a lyase enzyme, located in region 7p12.2-p12.1.

<span class="mw-page-title-main">Carbidopa</span> Chemical compound

Carbidopa (Lodosyn) is a drug given to people with Parkinson's disease in order to inhibit peripheral metabolism of levodopa. This property is significant in that it allows a greater proportion of administered levodopa to cross the blood–brain barrier for central nervous system effect, instead of being peripherally metabolised into substances unable to cross said barrier.

<span class="mw-page-title-main">Tetrahydrobiopterin</span> Chemical compound

Tetrahydrobiopterin (BH4, THB), also known as sapropterin (INN), is a cofactor of the three aromatic amino acid hydroxylase enzymes, used in the degradation of amino acid phenylalanine and in the biosynthesis of the neurotransmitters serotonin (5-hydroxytryptamine, 5-HT), melatonin, dopamine, norepinephrine (noradrenaline), epinephrine (adrenaline), and is a cofactor for the production of nitric oxide (NO) by the nitric oxide synthases. Chemically, its structure is that of a (dihydropteridine reductase) reduced pteridine derivative (quinonoid dihydrobiopterin).

<span class="mw-page-title-main">Clomipramine</span> Antidepressant

Clomipramine, sold under the brand name Anafranil among others, is a tricyclic antidepressant (TCA). It is used in the treatment of various conditions, most-notably obsessive–compulsive disorder but also many other disorders, including panic disorder, major depressive disorder, trichotilomania, body dysmorphic disorder and chronic pain. It has also been notably used to treat premature ejaculation and the cataplexy associated with narcolepsy.

<span class="mw-page-title-main">Benserazide</span> Chemical compound

Benserazide is a peripherally acting aromatic L-amino acid decarboxylase or DOPA decarboxylase inhibitor, which is unable to cross the blood–brain barrier.

<span class="mw-page-title-main">Enterochromaffin cell</span> Cell type

Enterochromaffin (EC) cells are a type of enteroendocrine cell, and neuroendocrine cell. They reside alongside the epithelium lining the lumen of the digestive tract and play a crucial role in gastrointestinal regulation, particularly intestinal motility and secretion. They were discovered by Nikolai Kulchitsky.

<span class="mw-page-title-main">Trazodone</span> Antidepressant medication

Trazodone, sold under many brand names, is an antidepressant medication. It is used to treat major depressive disorder, anxiety disorders, and insomnia. The medication is taken orally.

<span class="mw-page-title-main">Tianeptine</span> Atypical antidepressant

Tianeptine, sold under the brand names Stablon, Tatinol, and Coaxil among others, is an atypical tricyclic antidepressant which is used mainly in the treatment of major depressive disorder, although it may also be used to treat anxiety, asthma, and irritable bowel syndrome.

<span class="mw-page-title-main">Tryptophan hydroxylase</span> Class of enzymes

Tryptophan hydroxylase (TPH) is an enzyme (EC 1.14.16.4) involved in the synthesis of the monoamine neurotransmitter serotonin. Tyrosine hydroxylase, phenylalanine hydroxylase, and tryptophan hydroxylase together constitute the family of biopterin-dependent aromatic amino acid hydroxylases. TPH catalyzes the following chemical reaction

Cardiac fibrosis commonly refers to the excess deposition of extracellular matrix in the cardiac muscle, but the term may also refer to an abnormal thickening of the heart valves due to inappropriate proliferation of cardiac fibroblasts. Fibrotic cardiac muscle is stiffer and less compliant and is seen in the progression to heart failure. The description below focuses on a specific mechanism of valvular pathology but there are other causes of valve pathology and fibrosis of the cardiac muscle.

<span class="mw-page-title-main">Vortioxetine</span> Serotonin modulator antidepressant

Vortioxetine, sold under the brand names Trintellix and Brintellix among others, is a medication used to treat major depressive disorder. Its effectiveness is viewed as similar to that of other antidepressants. It is taken by mouth.

The pharmacology of antidepressants is not entirely clear. The earliest and probably most widely accepted scientific theory of antidepressant action is the monoamine hypothesis, which states that depression is due to an imbalance of the monoamine neurotransmitters. It was originally proposed based on the observation that certain hydrazine anti-tuberculosis agents produce antidepressant effects, which was later linked to their inhibitory effects on monoamine oxidase, the enzyme that catalyses the breakdown of the monoamine neurotransmitters. All currently marketed antidepressants have the monoamine hypothesis as their theoretical basis, with the possible exception of agomelatine which acts on a dual melatonergic-serotonergic pathway. Despite the success of the monoamine hypothesis it has a number of limitations: for one, all monoaminergic antidepressants have a delayed onset of action of at least a week; and secondly, there are a sizeable portion (>40%) of depressed patients that do not adequately respond to monoaminergic antidepressants. Further evidence to the contrary of the monoamine hypothesis are the recent findings that a single intravenous infusion with ketamine, an antagonist of the NMDA receptor — a type of glutamate receptor — produces rapid, robust and sustained antidepressant effects. Monoamine precursor depletion also fails to alter mood. To overcome these flaws with the monoamine hypothesis a number of alternative hypotheses have been proposed, including the glutamate, neurogenic, epigenetic, cortisol hypersecretion and inflammatory hypotheses. Another hypothesis that has been proposed which would explain the delay is the hypothesis that monoamines don't directly influence mood, but influence emotional perception biases.

Selective serotonin reuptake inhibitors, or serotonin-specific re-uptake inhibitor (SSRIs), are a class of chemical compounds that have application as antidepressants and in the treatment of depression and other psychiatric disorders. SSRIs are therapeutically useful in the treatment of panic disorder (PD), posttraumatic stress disorder (PTSD), social anxiety disorder, obsessive-compulsive disorder (OCD), premenstrual dysphoric disorder (PMDD), and anorexia. There is also clinical evidence of the value of SSRIs in the treatment of the symptoms of schizophrenia and their ability to prevent cardiovascular diseases.

<span class="mw-page-title-main">Monoamine precursor</span>

Monoamine precursors are precursors of monoamines and monoamine neurotransmitters in the body. The amino acids L-tryptophan and L-5-hydroxytryptophan are precursors of serotonin and melatonin, while the amino acids L-phenylalanine, L-tyrosine, and L-DOPA (levodopa) are precursors of dopamine, epinephrine (adrenaline), and norepinephrine (noradrenaline). Administration of monoamine precursors can increase the levels of monoamine neurotransmitters in the body and brain. Monoamine precursors may be used in combination with peripherally selective aromatic L-amino acid decarboxylase inhibitors such as carbidopa and benserazide. Carbidopa/levodopa is used to increase brain dopamine levels in the treatment of Parkinson's disease while carbidopa/oxitriptan (EVX-101) is under development as an antidepressant for possible use in the treatment of depression.

<span class="mw-page-title-main">Carbidopa/oxitriptan</span> Medication

Carbidopa/oxitriptan, or carbidopa/5-hydroxytryptophan (carbidopa/5-HTP), is a combination of 5-hydroxytryptophan (oxitriptan), a serotonin precursor, and carbidopa, a peripherally selective aromatic L-amino acid decarboxylase inhibitor, which is under development as an antidepressant for the treatment of depressive disorders. As of June 2020, it is in phase 1 clinical trials for this indication.

References

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