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Record Information
StatusDetected but not Quantified
Creation Date2005-11-16 15:48:42 UTC
Update Date2018-03-05 03:46:47 UTC
Secondary Accession Numbers
  • HMDB01229
Metabolite Identification
Common NameDopaquinone
DescriptionDopaquinone, also known as o-dopaquinone or L-dopaquinone, is a member of the class of compounds known as L-alpha-amino acids. L-alpha-amino acids are alpha-amino acids which have the L-configuration of the alpha-carbon atom. Dopaquinone is slightly soluble (in water) and a moderately acidic compound (based on its pKa). L-Dopaquinone is a metabolite of L-DOPA and a precursor of melanin. Melanin is synthesized from tyrosine by hydroxylation to dihydroxyphenylalanine (DOPA) and subsequent oxidation to dopaquinone. Both reactions are catalyzed by the enzyme tyrosinase, which is the rate-limiting step. Dopaquinone has an ortho-quinone ring, which is known to be neurotoxic and highly reactive with many other compounds (PMID: 413870 ). Dopaquinone typically combines with cysteine to form pheomelanin (a pigment-polymer). Alternatively, dopaquinone can be converted to leucodopachrome and eventually to eumelanin (also a pigment-polymer). Dopaquinone can be found in skin and feces. Within the cell, dopaquinone is primarily located in the cytoplasm. Dopaquinone is involved in several metabolic disorders, some of which include transient tyrosinemia, hawkinsinuria, tyrosinemia type I, and alkaptonuria. Chronically high levels of dopaquinone are associated with Parkinson's disease (PD). Many Parkinson's patients are treated with L-DOPA. However, long-term treatment with L-DOPA may actually worsen symptoms or result in neurotic and psychotic symptoms. These may be due to dopachrome and dopaquinone accumulating in the brain of L-DOPA treated patients (PMID: 19131041 , PMID: 12373519 ).
(S)-2-amino-3-(3,4-Dioxocyclohexa-1,5-dien-1-yl)propanoic acidGenerator
Dopaquinone, (S)-isomerMeSH
Chemical FormulaC9H9NO4
Average Molecular Weight195.1721
Monoisotopic Molecular Weight195.053157781
IUPAC Name(2S)-2-amino-3-(3,4-dioxocyclohexa-1,5-dien-1-yl)propanoic acid
Traditional Namedopaquinone
CAS Registry Number4430-97-1
InChI Identifier
Chemical Taxonomy
DescriptionThis compound belongs to the class of organic compounds known as l-alpha-amino acids. These are alpha amino acids which have the L-configuration of the alpha-carbon atom.
KingdomOrganic compounds
Super ClassOrganic acids and derivatives
ClassCarboxylic acids and derivatives
Sub ClassAmino acids, peptides, and analogues
Direct ParentL-alpha-amino acids
Alternative Parents
  • L-alpha-amino acid
  • O-benzoquinone
  • Quinone
  • Ketone
  • Amino acid
  • Cyclic ketone
  • Carboxylic acid
  • Monocarboxylic acid or derivatives
  • Amine
  • Hydrocarbon derivative
  • Primary amine
  • Organooxygen compound
  • Organonitrogen compound
  • Organic oxide
  • Organopnictogen compound
  • Primary aliphatic amine
  • Organic oxygen compound
  • Organic nitrogen compound
  • Carbonyl group
  • Aliphatic homomonocyclic compound
Molecular FrameworkAliphatic homomonocyclic compounds
External Descriptors

Biological location:


  Biofluid and excreta:



Naturally occurring process:

  Biological process:

    Biochemical pathway:

Physical Properties
Experimental Properties
Melting PointNot AvailableNot Available
Boiling PointNot AvailableNot Available
Water SolubilityNot AvailableNot Available
LogPNot AvailableNot Available
Predicted Properties
Water Solubility1.58 g/LALOGPS
pKa (Strongest Acidic)1.87ChemAxon
pKa (Strongest Basic)9.06ChemAxon
Physiological Charge0ChemAxon
Hydrogen Acceptor Count5ChemAxon
Hydrogen Donor Count2ChemAxon
Polar Surface Area97.46 ŲChemAxon
Rotatable Bond Count3ChemAxon
Refractivity49.48 m³·mol⁻¹ChemAxon
Polarizability18.06 ųChemAxon
Number of Rings1ChemAxon
Rule of FiveYesChemAxon
Ghose FilterYesChemAxon
Veber's RuleYesChemAxon
MDDR-like RuleYesChemAxon
Spectrum TypeDescriptionSplash Key
Predicted GC-MSPredicted GC-MS Spectrum - GC-MS (Non-derivatized) - 70eV, Positivesplash10-0fml-5900000000-3f77b48d5f42d8951324View in MoNA
Predicted GC-MSPredicted GC-MS Spectrum - GC-MS (1 TMS) - 70eV, Positivesplash10-00di-9570000000-5d835cfbd2b202044cb7View in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, Positivesplash10-0ufs-0900000000-093c511b443d87916930View in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, Positivesplash10-0ue9-1900000000-fc3bdef4314080b351c1View in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, Positivesplash10-0uxr-9200000000-07d0c6318c984ef80e41View in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, Negativesplash10-0006-0900000000-7481c7c6fe6294da272cView in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, Negativesplash10-002f-0900000000-04347396e1171463fb62View in MoNA
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, Negativesplash10-00di-7900000000-13ce3640966908fffe55View in MoNA
Biological Properties
Cellular Locations
  • Cytoplasm
Biofluid Locations
  • Feces
Tissue LocationNot Available
AlkaptonuriaThumbThumb?image type=greyscaleThumb?image type=simpleNot Available
Disulfiram Action PathwayThumbThumb?image type=greyscaleThumb?image type=simpleNot Available
Dopamine beta-hydroxylase deficiencyThumbThumb?image type=greyscaleThumb?image type=simpleNot Available
HawkinsinuriaThumbThumb?image type=greyscaleThumb?image type=simpleNot Available
Monoamine oxidase-a deficiency (MAO-A)ThumbThumb?image type=greyscaleThumb?image type=simpleNot Available
Normal Concentrations
FecesDetected but not Quantified Adult (>18 years old)BothNormal details
FecesDetected but not Quantified Adult (>18 years old)BothNormal details
FecesDetected but not Quantified Children (1-13 years old)BothNormal details
Abnormal Concentrations
FecesDetected but not Quantified Adult (>18 years old)BothICD details
FecesDetected but not Quantified Adult (>18 years old)BothCCD details
FecesDetected but not Quantified Adult (>18 years old)BothCCD details
FecesDetected but not Quantified Adult (>18 years old)BothICD details
Associated Disorders and Diseases
Disease ReferencesNone
Associated OMIM IDsNone
DrugBank IDNot Available
Phenol Explorer Compound IDNot Available
FoodDB IDFDB022501
KNApSAcK IDNot Available
Chemspider ID388447
KEGG Compound IDC00822
BiGG ID36114
Wikipedia LinkL-Dopaquinone
PubChem Compound439316
PDB IDNot Available
ChEBI ID16852
Synthesis ReferenceLand E J; Riley P A Spontaneous redox reactions of dopaquinone and the balance between the eumelanic and phaeomelanic pathways. Pigment cell research / sponsored by the European Society for Pigment Cell Research and the International Pigment Cell Society (2000), 13(4), 273-7.
Material Safety Data Sheet (MSDS)Not Available
General References
  1. Rorsman H, Tegner E: Biochemical observations in UV-induced pigmentation. Photodermatol. 1988 Feb;5(1):30-8. [PubMed:3281148 ]
  2. Tsukamoto K, Furue M, Sato Y, Takayama O, Akasu R, Ohtake N, Wakamatsu K, Ito S, Tamaki K, Shimada S: Generalized melanosis in metastatic malignant melanoma: the possible role of DOPAquinone metabolites. Dermatology. 1998;197(4):338-42. [PubMed:9873171 ]
  3. Graham DG, Tiffany SM, Vogel FS: The toxicity of melanin precursors. J Invest Dermatol. 1978 Feb;70(2):113-6. [PubMed:413870 ]
  4. Hattoria N, Wanga M, Taka H, Fujimura T, Yoritaka A, Kubo S, Mochizuki H: Toxic effects of dopamine metabolism in Parkinson's disease. Parkinsonism Relat Disord. 2009 Jan;15 Suppl 1:S35-8. doi: 10.1016/S1353-8020(09)70010-0. [PubMed:19131041 ]
  5. Kostrzewa RM, Kostrzewa JP, Brus R: Neuroprotective and neurotoxic roles of levodopa (L-DOPA) in neurodegenerative disorders relating to Parkinson's disease. Amino Acids. 2002;23(1-3):57-63. doi: 10.1007/s00726-001-0110-x. [PubMed:12373519 ]


General function:
Involved in oxidoreductase activity
Specific function:
This is a copper-containing oxidase that functions in the formation of pigments such as melanins and other polyphenolic compounds. Catalyzes the rate-limiting conversions of tyrosine to DOPA, DOPA to DOPA-quinone and possibly 5,6-dihydroxyindole to indole-5,6 quinone.
Gene Name:
Uniprot ID:
Molecular weight:
L-Dopa + Oxygen → Dopaquinone + Waterdetails
L-Tyrosine + Oxygen → Dopaquinone + Waterdetails
L-Dopa + L-Tyrosine + Oxygen → Dopaquinone + L-Dopa + Waterdetails