| Title | An action spectrum for the production of cis-urocanic acid in human skin in vivo. | | Author(s) | McLoone P, Simics E, Barton A, Norval M, Gibbs NK | | Institution | Medical Microbiology, University of Edinburgh, Edinburgh, UK. | | Source | J Invest Dermatol 2005 May; 124(5):1071-4. | | MeSH | Adult
Female
Humans
Male
Research Support, Non-U.S. Gov't
Skin
Sunscreening Agents
Ultraviolet Rays
Urocanic Acid
| | Abstract | Urocanic acid (UCA) is present at millimolar concentrations in mammalian epidermis and undergoes photoisomerization from the naturally occurring trans-isomer to the cis-isomer on exposure to ultraviolet radiation (UVR). Cis-UCA causes downregulation of various immune responses in mouse and human experimental models and has been proposed as both a chromophore and a mediator of UV-induced immune suppression. In this study, the wavelength dependence from 260-340 nm for trans to cis-UCA photoisomerization in human skin was analyzed in five healthy volunteers. The resulting action spectrum demonstrated maximal cis-UCA production in the UVB spectral region of 280-310 nm. This spectral peak is red-shifted to longer wavelengths compared with the erythemal action spectrum. The cis-UCA action spectrum can be used to predict the ability of sunscreens to protect against UVR-induced cis-UCA formation and may assist in explaining discrepancies between sunscreens' abilities to protect against erythema and photoimmunosuppression. | | Language | eng | | Pub Type(s) | Journal Article
| | PubMed ID | 15854050 |
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