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Reactive Oxygen Species Formation by UV‐A Irradiation of Urocanic Acid and the Role of Trace Metals in This Chemistry ¶
Author(s) -
Me Elton L.,
Perera Rushika,
Kuhn Richard J.,
Morrison Harry
Publication year - 2003
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/0031-8655(2003)0780567rosfbu2.0.co2
Subject(s) - chemistry , singlet oxygen , urocanic acid , photochemistry , metal , radical , reactivity (psychology) , irradiation , decomposition , oxygen , biochemistry , organic chemistry , histidine , physics , nuclear physics , medicine , alternative medicine , amino acid , pathology
We have extended our study of the decomposition of urocanic acid (UCA) with ultraviolet A radiation (UV‐A) by the self‐sensitized generation of singlet oxygen (see Photochem. Photobiol. 75, 565 [2002]). The chemistry has been found to be partially dependent on the presence of trace metal, most likely iron. Rigorous removal of metal impurities from the reaction mixture, using Chelex, retarded (but did not eliminate) the UV‐A–initiated UCA degradation. The addition of small amounts of ferric chloride to the Chelex‐treated solutions restored reactivity. Chelex treatment had a modest effect on the previously reported ability of UCA photoproducts to photonick supercoiled plasmid DNA. Also, photoinactivation of Sindbis virus on irradiation with the UCA photoproducts is now reported. Inactivation of the virus by a photoproduct mixture derived from a UCA solution that had been pretreated with Chelex was less rapid and gave better behaved time‐course plots than was observed for photoproducts from non–Chelex treated solutions. These results are particularly noteworthy in light of the ubiquitous presence of both UCA and iron in the skin.