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November 1961

Ultraviolet Induced Biochemical Alterations in Skin: I. Urocanic Acid

Author Affiliations


From the Biochemical Laboratories, Department of Dermatology, University of Oklahoma School of Medicine. This Research supported by NIH Grant A-2344-R2.

Arch Dermatol. 1961;84(5):717-719. doi:10.1001/archderm.1961.01580170011002

Urocanic acid is one of the compounds which undergoes structural alteration upon exposure of the skin to ultraviolet light. It is the purpose of this paper to characterize these changes and comment upon their significance.

At the Third International Congress of Biochemistry at Brussels in 1955, a group of Czechoslovakian investigators demonstrated prevalence of urocanic (imidazolearylic) acid in human sweat in contrast to other body fluids and speculated that this compound might play a role in the protection against 300 mμ radiation.1 They found that the concentration of urocanic acid in normal skins averaged 40-110 per ml.2 and that a significant amount of exhibited 300 mμ irradiation was absorbed by it.3 In 1957 Tabachnick showed that urocanic acid was the major ultraviolet light absorber in white guinea pig skin, constituting 0.7% of total dry weight of epidermis.4 We have shown5 the erythema protection conferred by

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