Record Information
Creation date2015-10-09 22:28:08 UTC
Update date2017-01-19 02:36:12 UTC
FoodComEx IDPC000087
FoodDB RecordFDB000921
Chemical Information
NameUrocanic acid
DescriptionUrocanic acid is an intermediate in the catabolism of L-histidine.; Urocanic 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. Urocanic acid is found in mung bean.
CAS Number104-98-3
3-(1H-Imidazol-4-yl)-2-propenoic acidHMDB
3-(1H-Imidazol-4-yl)-2-propenoic acid, 9CIdb_source
3-(1H-Imidazol-4-yl)acrylic acidbiospider
3-(4-Imidazolyl)acrylic acidHMDB
4-Imidazoleacrylic acid, 8CIdb_source
5-Imidazoleacrylate;imidazoleacrylic acidbiospider
5-Imidazoleacrylic acidHMDB
Imidazole-4-acrylic acidHMDB
Imidazoleacrylic acidHMDB
Urocaninic aciddb_source
Chemical FormulaC6H6N2O2
IUPAC name(2Z)-3-(1H-imidazol-5-yl)prop-2-enoic acid
InChI IdentifierInChI=1S/C6H6N2O2/c9-6(10)2-1-5-3-7-4-8-5/h1-4H,(H,7,8)(H,9,10)/b2-1-
Isomeric SMILESOC(=O)\C=C/C1=CN=CN1
Average Molecular Weight138.124
Monoisotopic Molecular Weight138.042927446
Chemical Taxonomy
Description Belongs to the class of organic compounds known as imidazolyl carboxylic acids and derivatives. These are organic compounds containing a carboxylic acid chain (of at least 2 carbon atoms) linked to an imidazole ring.
KingdomOrganic compounds
Super ClassOrganoheterocyclic compounds
Sub ClassImidazoles
Direct ParentImidazolyl carboxylic acids and derivatives
Alternative Parents
  • Imidazolyl carboxylic acid derivative
  • Heteroaromatic compound
  • Azacycle
  • Monocarboxylic acid or derivatives
  • Carboxylic acid
  • Carboxylic acid derivative
  • Organic nitrogen compound
  • Organic oxygen compound
  • Organopnictogen compound
  • Organic oxide
  • Hydrocarbon derivative
  • Organooxygen compound
  • Organonitrogen compound
  • Carbonyl group
  • Aromatic heteromonocyclic compound
Molecular FrameworkAromatic heteromonocyclic compounds
External Descriptors
Physico-Chemical Properties - Experimental
Experimental logPNot Available
Experimental Water Solubility1.5 mg/mL at 17 oCYALKOWSKY,SH & DANNENFELSER,RM (1992)
Melting PointMp 243-245°DFC
Foods of Origin
FoodContent Range AverageReference
Production Data
Production Methodcommercial
Production Method ReferenceNot Available
Production Method Reference FileNot Available
Quantity AvailableProduction upon request, up to 1 g
Delivery TimeNot Available
Storage Formsolid
Storage Conditions-80°C
StabilityNot Available
PurityNot Available
Spectral Data Upon RequestNot Available
Provider Information
Contact NameContact InstitutionContact Email
Rosa Vazquez
Commercial Vendors
AKSci 1164AA