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Record Information
StatusDetected but not Quantified
Creation Date2005-11-16 15:48:42 UTC
Update Date2021-09-14 15:20:03 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)-isomerHMDB
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
Description 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:


Naturally occurring process:

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 FilterNoChemAxon
Veber's RuleNoChemAxon
MDDR-like RuleNoChemAxon


Spectrum TypeDescriptionSplash KeyDeposition DateView
Predicted GC-MSPredicted GC-MS Spectrum - GC-MS (Non-derivatized) - 70eV, Positivesplash10-0fml-5900000000-3f77b48d5f42d89513242017-09-01View Spectrum
Predicted GC-MSPredicted GC-MS Spectrum - GC-MS (1 TMS) - 70eV, Positivesplash10-00di-9570000000-5d835cfbd2b202044cb72017-10-06View Spectrum
MSMass Spectrum (Electron Ionization)splash10-0fml-5900000000-3f77b48d5f42d89513242021-09-05View Spectrum


Spectrum TypeDescriptionSplash KeyDeposition DateView
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, Positivesplash10-0ufs-0900000000-093c511b443d879169302017-09-01View Spectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, Positivesplash10-0ue9-1900000000-fc3bdef4314080b351c12017-09-01View Spectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, Positivesplash10-0uxr-9200000000-07d0c6318c984ef80e412017-09-01View Spectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, Negativesplash10-0006-0900000000-7481c7c6fe6294da272c2017-09-01View Spectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, Negativesplash10-002f-0900000000-04347396e1171463fb622017-09-01View Spectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, Negativesplash10-00di-7900000000-13ce3640966908fffe552017-09-01View Spectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, Negativesplash10-0006-0900000000-c319fd057861dc7d7ad42021-09-08View Spectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, Negativesplash10-00e9-3900000000-b64033d6c2ec2ca4314b2021-09-08View Spectrum
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, Negativesplash10-00di-5900000000-cde5f7d52f36428ed06e2021-09-08View Spectrum
Biological Properties
Cellular Locations
  • Cytoplasm
Biospecimen Locations
  • Feces
Tissue LocationsNot Available
Normal Concentrations
FecesDetected but not QuantifiedNot QuantifiedAdult (>18 years old)BothNormal details
FecesDetected but not QuantifiedNot QuantifiedChildren (1-13 years old)BothNormal details
Abnormal Concentrations
FecesDetected but not QuantifiedNot QuantifiedAdult (>18 years old)BothCCD details
FecesDetected but not QuantifiedNot QuantifiedAdult (>18 years old)BothIleal Crohn's disease details
Associated Disorders and Diseases
Disease ReferencesNone
Associated OMIM IDsNone
DrugBank IDNot Available
Phenol Explorer Compound IDNot Available
FooDB IDFDB022501
KNApSAcK IDNot Available
Chemspider ID388447
KEGG Compound IDC00822
BiGG ID36114
Wikipedia LinkL-Dopaquinone
PubChem Compound439316
PDB IDNot Available
ChEBI ID16852
Food Biomarker OntologyNot Available
MarkerDB IDNot Available
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