Abstract
Urocanic acid (UCA) is present at millimolar concentrations in mammalian epidermis and undergoes photo-isomerization 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. Copyright © 2005 by The Society for Investigative Dermatology, Inc.
| Original language | English |
|---|---|
| Pages (from-to) | 1071-1074 |
| Number of pages | 3 |
| Journal | Journal of Investigative Dermatology |
| Volume | 124 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - May 2005 |
Keywords
- Skin
- Urocanic acid
- UV radiation