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Photobiological model studies on perester and pyridone tert-butoxyl radical sources (photo-Fenton-type reagents): 2’-deoxyguanosine modification by methyl radicals generated through competitive ß-cleavage in aqueous media

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Abstract

In aqueous solution, UV irradiation of the photo-Fenton-type reagents perester 1 and N-tert-butoxypyridone 2 leads to the formation of tert-butoxyl radicals and methyl radicals as confirmed by product studies and by spin trapping with 5,5-dimethyl-1-pyrroline N-oxide (DMPO), followed by EPR spectroscopy. The methyl radicals result from the initially released tert-butoxyl radicals through ß-cleavage, a fragmentation pathway, which dominates at lower DMPO concentrations. In the presence of 2’-deoxyguanosine (dG), both photochemical radical sources afford 8-MedG [(2.3 ± 0.3)%] and N7-MedG [(0.27 ± 0.05)%] as modified products, whereas the direct reaction of the tert-butoxyl radicals with dG cannot compete with this ß-cleavage process.

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Authors and Affiliations

  1. Institut für Organische Chemie, Am Hubland, D-97074, Würzburg, Germany

    Waldemar Adam, Stefan Marquardt & Chantu R. Saha-Möller

  2. Institut für Lebensmittelchemie, Universität Würzburg, Am Hubland, D-97074, Würzburg, Germany

    Diana Kemmer & Peter Schreier

Authors
  1. Waldemar Adam
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  2. Stefan Marquardt
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  3. Diana Kemmer
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  4. Chantu R. Saha-Möller
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  5. Peter Schreier
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Correspondence to Waldemar Adam.

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Adam, W., Marquardt, S., Kemmer, D. et al. Photobiological model studies on perester and pyridone tert-butoxyl radical sources (photo-Fenton-type reagents): 2’-deoxyguanosine modification by methyl radicals generated through competitive ß-cleavage in aqueous media. Photochem Photobiol Sci 1, 609–612 (2002). https://doi.org/10.1039/b203845e

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