Accession NumberDB02959  (EXPT01780)
TypeSmall Molecule
GroupsApproved, Nutraceutical

5-Hydroxytryptophan (5-HTP), also known as oxitriptan (INN), is a naturally occurring amino acid and chemical precursor as well as a metabolic intermediate in the biosynthesis of the neurotransmitters serotonin and melatonin from tryptophan. 5-HTP is sold over-the-counter in the United Kingdom, United States and Canada as a dietary supplement for use as an antidepressant, appetite suppressant, and sleep aid, and is also marketed in many European countries for the indication of major depression under trade names like Cincofarm, Levothym, Levotonine, Oxyfan, Telesol, Tript-OH, and Triptum. Several double-blind placebo-controlled clinical trials have demonstrated the effectiveness of 5-HTP in the treatment of depression, though a lack of high quality studies has been noted. More and larger studies are needed to determine if 5-HTP is truly effective in treating depression.

5-Hydroxytryptophan L-form
Hydroxy-5 L-tryptophane
External IDs Not Available
Product Ingredients Not Available
Approved Prescription ProductsNot Available
Approved Generic Prescription ProductsNot Available
Approved Over the Counter ProductsNot Available
Unapproved/Other Products Not Available
International Brands
Brand mixturesNot Available
CAS number4350-09-8
WeightAverage: 220.2246
Monoisotopic: 220.08479226
Chemical FormulaC11H12N2O3
(2S)-2-amino-3-(5-hydroxy-1H-indol-3-yl)propanoic acid
N[[email protected]@H](CC1=CNC2=C1C=C(O)C=C2)C(O)=O

For use as an antidepressant, appetite suppressant, and sleep aid.

Structured Indications Not Available

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.

Mechanism of action
TargetKindPharmacological actionActionsOrganismUniProt ID
Tryptophan--tRNA ligase 2ProteinunknownNot AvailableDeinococcus radiodurans (strain ATCC 13939 / DSM 20539 / JCM 16871 / LMG 4051 / NBRC 15346 / NCIMB 9279 / R1 / VKM B-1422)Q9RVD6 details
Related Articles
AbsorptionNot Available
Volume of distributionNot Available
Protein bindingNot Available

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. This reaction occurs both in nervous tissue and in the liver.

Route of eliminationNot Available
Half lifeNot Available
ClearanceNot Available
ToxicityNot Available
Affected organisms
  • Humans and other mammals
PathwayCategorySMPDB ID
Tryptophan MetabolismMetabolicSMP00063
Pharmacogenomic Effects/ADRs Not Available
Drug Interactions Not Available
Food InteractionsNot Available
Synthesis Reference

British Patent 845,034.

General References
  1. Turner EH, Blackwell AD: 5-Hydroxytryptophan plus SSRIs for interferon-induced depression: synergistic mechanisms for normalizing synaptic serotonin. Med Hypotheses. 2005;65(1):138-44. [PubMed:15893130 ]
  2. Shaw K, Turner J, Del Mar C: Tryptophan and 5-hydroxytryptophan for depression. Cochrane Database Syst Rev. 2002;(1):CD003198. [PubMed:11869656 ]
  3. Rahman MK, Nagatsu T, Sakurai T, Hori S, Abe M, Matsuda M: 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. 1982 Oct;32(5):803-11. [PubMed:6983619 ]
  4. Nakatani Y, Sato-Suzuki I, Tsujino N, Nakasato A, Seki Y, Fumoto M, Arita H: Augmented brain 5-HT crosses the blood-brain barrier through the 5-HT transporter in rat. Eur J Neurosci. 2008 May;27(9):2466-72. doi: 10.1111/j.1460-9568.2008.06201.x. [PubMed:18445233 ]
  5. Bouchard S, Roberge AG: Biochemical properties and kinetic parameters of dihydroxyphenylalanine--5-hydroxytryptophan decarboxylase in brain, liver, and adrenals of cat. Can J Biochem. 1979 Jul;57(7):1014-8. [PubMed:39668 ]
  6. Amamoto T, Sarai K: 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. 1976 Sep;25(2-3):135-40. [PubMed:1088369 ]
  7. Magnussen I, Jensen TS, Rand JH, Van Woert MH: Plasma accumulation of metabolism of orally administered single dose L-5-hydroxytryptophan in man. Acta Pharmacol Toxicol (Copenh). 1981 Sep;49(3):184-9. [PubMed:6175178 ]
  8. Birdsall TC: 5-Hydroxytryptophan: a clinically-effective serotonin precursor. Altern Med Rev. 1998 Aug;3(4):271-80. [PubMed:9727088 ]
  9. Sternberg EM, Van Woert MH, Young SN, Magnussen I, Baker H, Gauthier S, Osterland CK: Development of a scleroderma-like illness during therapy with L-5-hydroxytryptophan and carbidopa. N Engl J Med. 1980 Oct 2;303(14):782-7. [PubMed:6997735 ]
  10. Caruso I, Sarzi Puttini P, Cazzola M, Azzolini V: Double-blind study of 5-hydroxytryptophan versus placebo in the treatment of primary fibromyalgia syndrome. J Int Med Res. 1990 May-Jun;18(3):201-9. [PubMed:2193835 ]
  11. Trouillas P, Serratrice G, Laplane D, Rascol A, Augustin P, Barroche G, Clanet M, Degos CF, Desnuelle C, Dumas R, et al.: Levorotatory form of 5-hydroxytryptophan in Friedreich's ataxia. Results of a double-blind drug-placebo cooperative study. Arch Neurol. 1995 May;52(5):456-60. [PubMed:7733839 ]
  12. De Benedittis G, Massei R: Serotonin precursors in chronic primary headache. A double-blind cross-over study with L-5-hydroxytryptophan vs. placebo. J Neurosurg Sci. 1985 Jul-Sep;29(3):239-48. [PubMed:3913752 ]
External Links
ATC CodesN06AX01 — Oxitriptan
AHFS CodesNot Available
PDB Entries
FDA labelNot Available
MSDSDownload (1.4 MB)
Clinical Trials
Clinical Trials
Not AvailableCompletedBasic ScienceIrritable Bowel Syndrome (IBS)1
ManufacturersNot Available
PackagersNot Available
Dosage formsNot Available
PricesNot Available
PatentsNot Available
Experimental Properties
melting point (°C)295-297British Patent 845,034.
Predicted Properties
Water Solubility3.63 mg/mLALOGPS
pKa (Strongest Acidic)2.15ChemAxon
pKa (Strongest Basic)9.18ChemAxon
Physiological Charge0ChemAxon
Hydrogen Acceptor Count4ChemAxon
Hydrogen Donor Count4ChemAxon
Polar Surface Area99.34 Å2ChemAxon
Rotatable Bond Count3ChemAxon
Refractivity58.18 m3·mol-1ChemAxon
Polarizability22.03 Å3ChemAxon
Number of Rings2ChemAxon
Rule of FiveYesChemAxon
Ghose FilterNoChemAxon
Veber's RuleNoChemAxon
MDDR-like RuleNoChemAxon
Predicted ADMET features
Human Intestinal Absorption+0.9891
Blood Brain Barrier+0.8916
Caco-2 permeable-0.7442
P-glycoprotein substrateNon-substrate0.5159
P-glycoprotein inhibitor INon-inhibitor0.9971
P-glycoprotein inhibitor IINon-inhibitor0.9838
Renal organic cation transporterNon-inhibitor0.8689
CYP450 2C9 substrateNon-substrate0.8399
CYP450 2D6 substrateNon-substrate0.7445
CYP450 3A4 substrateNon-substrate0.7324
CYP450 1A2 substrateNon-inhibitor0.9045
CYP450 2C9 inhibitorNon-inhibitor0.9072
CYP450 2D6 inhibitorNon-inhibitor0.9231
CYP450 2C19 inhibitorNon-inhibitor0.9025
CYP450 3A4 inhibitorNon-inhibitor0.9642
CYP450 inhibitory promiscuityLow CYP Inhibitory Promiscuity0.8947
Ames testNon AMES toxic0.9133
BiodegradationNot ready biodegradable0.7897
Rat acute toxicity2.9260 LD50, mol/kg Not applicable
hERG inhibition (predictor I)Weak inhibitor0.9784
hERG inhibition (predictor II)Non-inhibitor0.9299
ADMET data is predicted using admetSAR, a free tool for evaluating chemical ADMET properties. (23092397 )
Mass Spec (NIST)Not Available
Spectrum TypeDescriptionSplash Key
GC-MSGC-MS Spectrum - GC-MS (4 TMS)splash10-0006-0390000000-d4e36a90b7591787e67bView in MoNA
GC-MSGC-MS Spectrum - GC-MS (3 TMS)splash10-0006-1390000000-b0af49def87c0211653cView in MoNA
GC-MSGC-MS Spectrum - GC-MS (3 TMS)splash10-014i-0390000000-8b7f6cc8f51c032dd86dView in MoNA
Predicted GC-MSPredicted GC-MS Spectrum - GC-MSNot Available
GC-MSGC-MS Spectrum - GC-EI-TOFsplash10-014i-0390000000-88191cf8140abf0f3205View in MoNA
GC-MSGC-MS Spectrum - GC-EI-TOFsplash10-0006-0290000000-a30ea02ff8d4d14ba7a4View in MoNA
GC-MSGC-MS Spectrum - GC-MSsplash10-0006-0390000000-d4e36a90b7591787e67bView in MoNA
GC-MSGC-MS Spectrum - GC-MSsplash10-0006-1390000000-b0af49def87c0211653cView in MoNA
GC-MSGC-MS Spectrum - GC-MSsplash10-014i-0390000000-8b7f6cc8f51c032dd86dView in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QTOF , positivesplash10-0udi-0790000000-a699ed429ebd1609f995View in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QTOF , positivesplash10-03e9-0900000000-bbd302f8ff188f6cf93dView in MoNA
LC-MS/MSLC-MS/MS Spectrum - LC-ESI-QTOF , positivesplash10-053r-0900000000-6cc3ba396b1cfa8db1e6View in MoNA
LC-MS/MSLC-MS/MS Spectrum - , positivesplash10-053r-2900000000-90a465428eacaced71e2View in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, PositiveNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, PositiveNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, PositiveNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, NegativeNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, NegativeNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, NegativeNot Available
1D NMR1H NMR SpectrumNot Available
DescriptionThis compound belongs to the class of organic compounds known as serotonins. These are compounds containing a serotonin moiety, which consists of an indole that bears an aminoethyl a position 2 and a hydroxyl group at position 5.
KingdomOrganic compounds
Super ClassOrganoheterocyclic compounds
ClassIndoles and derivatives
Sub ClassTryptamines and derivatives
Direct ParentSerotonins
Alternative ParentsIndolyl carboxylic acids and derivatives / 3-alkylindoles / L-alpha-amino acids / Hydroxyindoles / 1-hydroxy-2-unsubstituted benzenoids / Aralkylamines / Substituted pyrroles / Heteroaromatic compounds / Amino acids / Monocarboxylic acids and derivatives
SubstituentsSerotonin / Indolyl carboxylic acid derivative / Alpha-amino acid / Alpha-amino acid or derivatives / 3-alkylindole / L-alpha-amino acid / Hydroxyindole / Indole / Aralkylamine / 1-hydroxy-2-unsubstituted benzenoid
Molecular FrameworkAromatic heteropolycyclic compounds
External Descriptorsnon-proteinogenic L-alpha-amino acid, 5-hydroxytryptophan, hydroxy-L-tryptophan (CHEBI:17780 )


Deinococcus radiodurans (strain ATCC 13939 / DSM 20539 / JCM 16871 / LMG 4051 / NBRC 15346 / NCIMB 9279 / R1 / VKM B-1422)
Pharmacological action
General Function:
Tryptophan-trna ligase activity
Specific Function:
Catalyzes the formation of 5'adenyl-Trp and tRNA(Trp) but with 5-fold less activity than TrpRS. Increases the solubility of the nitric oxide synthase oxygenase (nos), as well as its affinity for substrate L-arginine and its nitric-oxide synthase activity. The complex between trpS2 and nos catalyzes the regioselective nitration of tryptophan at the 4-position.
Gene Name:
Uniprot ID:
Uniprot Name:
Tryptophan--tRNA ligase 2
Molecular Weight:
38179.35 Da
  1. Overington JP, Al-Lazikani B, Hopkins AL: How many drug targets are there? Nat Rev Drug Discov. 2006 Dec;5(12):993-6. [PubMed:17139284 ]
  2. Imming P, Sinning C, Meyer A: Drugs, their targets and the nature and number of drug targets. Nat Rev Drug Discov. 2006 Oct;5(10):821-34. [PubMed:17016423 ]
Drug created on June 13, 2005 07:24 / Updated on September 01, 2017 10:58