Urocanic acid

Urocanic acid is a naturally occurring organic compound found predominantly in the upper layers of mammalian skin. It is produced from L-histidine by the enzyme histidine ammonia lyase during histidine metabolism. Urocanic acid exists mainly as the trans isomer under physiological conditions but can be converted to its cis form upon exposure to ultraviolet radiation (UVR)[7]. In the stratum corneum of human skin, it acts as a major endogenous absorber of UVB light and contributes to photoprotection against DNA damage[1][7]. The cis isomer has immunomodulatory properties and has been linked with cutaneous diseases such as atopic dermatitis and urticaria; it also associates with systemic diseases including multiple sclerosis[3]. Urocanic acid does not function as a classical therapeutic target like an enzyme or receptor but rather serves important roles in physiology and disease biomarker research. Deficiency or dysregulation can be associated with metabolic disorders such as urocanic aciduria due to inherited defects in downstream enzymes like urocanase[7].

Other names

trans-urocanic acidcis-urocanic acidurocanate(2E)-3-(1H-imidazol-4-yl)prop-2-enoic acid3-(1H-imidazol-5-yl)-2E-propenoic acid[7][10][5]