Adam Waldemar, Marquardt Stefan, Kemmer Diana, Saha-Möller Chantu R, Schreier Peter
Institut für Organische Chemie, Am Hubland, D-97074 Würzburg, Germany.
Photochem Photobiol Sci. 2002 Aug;1(8):609-12. doi: 10.1039/b203845e.
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 beta-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 beta-cleavage process.
在水溶液中，通过产物研究以及用5,5-二甲基-1-吡咯啉N-氧化物（DMPO）进行自旋捕获并随后进行电子顺磁共振光谱（EPR）证实，光芬顿型试剂过氧酯1和N-叔丁氧基吡啶酮2的紫外线照射会导致叔丁氧基自由基和甲基自由基的形成。甲基自由基是由最初释放的叔丁氧基自由基通过β-裂解产生的，β-裂解是一种碎片化途径，在较低的DMPO浓度下占主导地位。在2'-脱氧鸟苷（dG）存在的情况下，两种光化学自由基源都能产生8-甲基鸟嘌呤（8-MedG）[（2.3±0.3）%]和N7-甲基鸟嘌呤（N7-MedG）[（0.27±0.05）%]作为修饰产物，而叔丁氧基自由基与dG的直接反应无法与这种β-裂解过程竞争。
