Human Metabolome Database Version 3.5

Showing metabocard for Urocanic acid (HMDB00301)

Record Information
Version 3.5
Creation Date 2005-11-16 08:48:42 -0700
Update Date 2013-04-19 16:30:17 -0600
Secondary Accession Numbers
  • HMDB02280
Metabolite Identification
Common Name Urocanic acid
Description Urocanic acid is a breakdown (deamination) product of histidine. In the liver, urocanic acid is an intermediate in the conversion of histidine to glutamic acid, whereas in the epidermis, it accumulates and may be both a UV protectant and an immunoregulator. Urocanic acid (UA) exists as a trans isomer (t-UA, approximately 30 mg/cm2) in the uppermost layer of the skin (stratum corneum). t-UA is formed as the cells of the second layer of skin become metabolically inactive. During this process, proteins and membranes degrade, histidine is released, and histidase (histidine ammonia lyase) catalyzes the deamination of histidine to form t-UA. t-UA accumulates in the epidermis until removal by either the monthly skin renewal cycle or sweat. Upon absorption of UV light, the naturally occurring t-UA isomerizes to its cis form, c-UA. Because DNA lesions (e.g., pyrimidine dimers) in the lower epidermis can result from UV-B absorption, initial research proposed that t-UA acted as a natural sunscreen absorbing UV-B in the stratum corneum before the damaging rays could penetrate into lower epidermal zones. Researchers have found that c-UA also suppresses contact hypersensitivity and delayed hypersensitivity, reduces the Langerhans cell count in the epidermis, prolongs skin-graft survival time, and affects natural killer cell activity.
Structure Thumb
Download: MOL | SDF | PDB | SMILES | InChI
Display: 2D Structure | 3D Structure
  1. 3-(1H-Imidazol-4-yl)-2-propenoate
  2. 3-(1H-Imidazol-4-yl)-2-propenoic acid
  3. 3-(1H-Imidazol-4-yl)acrylate
  4. 3-(1H-Imidazol-4-yl)acrylic acid
  5. 3-(4-Imidazolyl)acrylate
  6. 3-(4-Imidazolyl)acrylic acid
  7. 5-Imidazoleacrylate
  8. 5-Imidazoleacrylic acid
  9. Imidazole-4-acrylate
  10. Imidazole-4-acrylic acid
  11. Imidazoleacrylic acid
  12. Urocanate
  13. Urocanic acid
Chemical Formula C6H6N2O2
Average Molecular Weight 138.124
Monoisotopic Molecular Weight 138.042927446
IUPAC Name (2E)-3-(1H-imidazol-4-yl)prop-2-enoic acid
Traditional IUPAC Name trans-urocanic acid
CAS Registry Number 104-98-3
InChI Identifier InChI=1S/C6H6N2O2/c9-6(10)2-1-5-3-7-4-8-5/h1-4H,(H,7,8)(H,9,10)/b2-1+
Chemical Taxonomy
Kingdom Organic Compounds
Super Class Aromatic Heteromonocyclic Compounds
Class Azoles
Sub Class Imidazoles
Other Descriptors
  • Aromatic Heteromonocyclic Compounds
  • urocanic acid(ChEBI)
  • Allyl Alcohol
  • Carboxylic Acid
  • Enone
Direct Parent Imidazolyl Carboxylic Acids and Derivatives
Status Detected and Quantified
  • Endogenous
  • Component of Histidine metabolism
  • Component of Nitrogen metabolism
Application Not Available
Cellular locations
  • Cytoplasm (predicted from logP)
Physical Properties
State Solid
Experimental Properties
Property Value Reference
Melting Point 225 °C Not Available
Boiling Point Not Available Not Available
Water Solubility 1.5 mg/mL at 17 °C Not Available
LogP Not Available Not Available
Predicted Properties
Property Value Source
Water Solubility 42.5 g/L ALOGPS
LogP 0.22 ALOGPS
LogP -1 ChemAxon
LogS -0.51 ALOGPS
pKa (strongest acidic) 3.85 ChemAxon
pKa (strongest basic) 6.13 ChemAxon
Hydrogen Acceptor Count 3 ChemAxon
Hydrogen Donor Count 2 ChemAxon
Polar Surface Area 65.98 A2 ChemAxon
Rotatable Bond Count 2 ChemAxon
Refractivity 35.57 ChemAxon
Polarizability 13.09 ChemAxon
Formal Charge 0 ChemAxon
Physiological Charge -1 ChemAxon
Gas-MS Spectrum
1H NMR Spectrum
MS/MS Spectrum Quattro_QQQ 10
MS/MS Spectrum Quattro_QQQ 25
MS/MS Spectrum Quattro_QQQ 40
MS/MS Spectrum EI-B (HITACHI M-80)
MS/MS Spectrum LC-ESI-QQ (API3000, Applied Biosystems) 10
MS/MS Spectrum LC-ESI-QQ (API3000, Applied Biosystems) 20
MS/MS Spectrum LC-ESI-QQ (API3000, Applied Biosystems) 30
MS/MS Spectrum LC-ESI-QQ (API3000, Applied Biosystems) 40
MS/MS Spectrum LC-ESI-QQ (API3000, Applied Biosystems) 50
MS/MS Spectrum GC-EI-TOF (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies)
MS/MS Spectrum GC-EI-TOF (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies )
MS/MS Spectrum GC-EI-TOF (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies)
MS/MS Spectrum LC-ESI-QTOF (UPLC Q-Tof Premier, Waters)
MS/MS Spectrum LC-ESI-QTOF (UPLC Q-Tof Premier, Waters)
MS/MS Spectrum GC-MS
[1H,13C] 2D NMR Spectrum
Biological Properties
Cellular Locations
  • Cytoplasm (predicted from logP)
Biofluid Locations
  • Blood
  • Urine
Tissue Location
  • Liver
  • Skin
Name SMPDB Link KEGG Link
Histidine Metabolism SMP00044 map00340 Link_out
Ammonia Recycling SMP00009 map00910 Link_out
Normal Concentrations
Biofluid Status Value Age Sex Condition Reference
Blood Detected and Quantified
0.43 +/- 0.33 uM Adult (>18 years old) Both Normal
Urine Detected and Quantified
0.29 (0.0-0.78) umol/mmol creatinine Adult (>18 years old) Both Normal
  • Geigy Scient...
  • West Cadwell...
  • Basel, Switz...
Abnormal Concentrations
Not Available
Associated Disorders and Diseases
Disease References None
Associated OMIM IDs None
DrugBank ID DB01971 Link_out
DrugBank Metabolite ID Not Available
Phenol Explorer Compound ID Not Available
Phenol Explorer Metabolite ID Not Available
FoodDB ID FDB000921
KNApSAcK ID Not Available
Chemspider ID 643824 Link_out
KEGG Compound ID C00785 Link_out
BioCyc ID UROCANATE Link_out
BiGG ID 35990 Link_out
Wikipedia Link Urocanic acid Link_out
NuGOwiki Link HMDB00301 Link_out
Metagene Link HMDB00301 Link_out
METLIN ID 298 Link_out
PubChem Compound 736715 Link_out
PDB ID URO Link_out
ChEBI ID 30817 Link_out
Synthesis Reference Yamamoto, Kozo; Sato, Tadashi; Tosa, Tetsuya; Chibata, Ichiro. Continuous production of urocanic acid by immobilized Achromobacter liquidum cells. Biotechnology and Bioengineering (1974), 16(12), 1601-10.
Material Safety Data Sheet (MSDS) Download (PDF)
General References
  1. Sastry CM, Whitmore SE, Breysse PN, Morison WL, Strickland PT: The effect of clinical UVA/B exposures on urinary urocanic acid isomer levels in individuals with caucasian type (II/III) skin types. Dermatol Online J. 2005 Dec 1;11(3):1. Pubmed: 16409897 Link_out
  2. Hug DH, Hunter JK, Dunkerson DD: The potential role for urocanic acid and sunlight in the immune suppression associated with protein malnutrition. J Photochem Photobiol B. 1998 Jul 10;44(2):117-23. Pubmed: 9757593 Link_out
  3. Snellman E, Jansen CT, Laihia JK, Milan T, Koulu L, Leszczynski K, Pasanen P: Urocanic acid concentration and photoisomerization in Caucasian skin phototypes. Photochem Photobiol. 1997 May;65(5):862-5. Pubmed: 9155258 Link_out
  4. Schwarz W, Langer K, Haag A: High-performance liquid chromatographic determination of (Z)-and (E)-urocanic acid in human skin. J Chromatogr. 1984 Sep 14;310(1):188-92. Pubmed: 6501514 Link_out
  5. Hermann K, Abeck D: Determination of histidine and urocanic acid isomers in the human skin by high-performance capillary electrophoresis. J Chromatogr B Biomed Sci Appl. 2000 Nov 10;749(1):41-7. Pubmed: 11129077 Link_out
  6. Kinuta M, Kinuta K, Yamada H, Abe T, Yoshida Y, Araki K, Li SA, Otsuka A, Nakanishi A, Moriyama Y, Takei K: Formation of S-[2-carboxy-1-(1H-imidazol-4-yl) ethyl]glutathione, a new metabolite of L-histidine, from cis-urocanic acid and glutathione by the action of glutathione S-transferase. Electrophoresis. 2003 Sep;24(18):3212-8. Pubmed: 14518047 Link_out
  7. Yokoya S, Tokuhiro E, Suwa S, Maesaka H: Measurement of the skin urocanic acid content in normal and histidinemic infants. Eur J Pediatr. 1983 Sep;140(4):330-2. Pubmed: 6628454 Link_out
  8. Morrison H: Photochemistry and photobiology of urocanic acid. Photodermatol. 1985 Jun;2(3):158-65. Pubmed: 3895185 Link_out

Name: Histidine ammonia-lyase
L-Histidine unknown Urocanic acid + Ammonia details
Gene Name: HAL
Uniprot ID: P42357 Link_out
Protein Sequence: FASTA
Gene Sequence: FASTA
Name: Urocanate hydratase
4-Imidazolone-5-propionic acid unknown Urocanic acid + Water details
Gene Name: UROC1
Uniprot ID: Q96N76 Link_out
Protein Sequence: FASTA
Gene Sequence: FASTA