Generation of 2 '-Deoxyadenosine N(6)-Aminyl Radicals from the Photolysis of Phenylhydrazone Derivatives

作者：Kuttappan Nair Vandana; Samson Thibault Francois; Wagner J Richard^*

来源：Chemical Research in Toxicology, 2010, 23(1): 48-54.

DOI：10.1021/tx900268r

Nitrogen-centered radicals are major species generated by the addition of hydroxyl radicals and the one-electron oxidation of adenine derivatives. Aminyl radicals are also generated in the decomposition of adenine chloramines upon reaction of hypochlorite. Here, we report the photochemistry of modified 2'-dcoxyadenosine (dAdo) containing photoactive hydrazone substituents its a model to investigate the chemistry of dAdo N(6)-aminyl radicals. Derivatives of dAdo containing a phenylhydrazone moiety at N6 displayed UV absorption between 300 and 400 nm. Upon UV photolysis in the presence of a H-donor, that is, glutathione, two major products were formed, dAdo and benzaldehyde, indicating efficient homolytic cleavage to dAdo N(6)-aminyl radicals and benzylidene iminyl radicals. dAdo N(6)-phenylhydrazone was photolyzed in the presence of a molar excess of nonmodified dAdo to mimic the reactions taking place in DNA, and the major photoproducts were identified by high-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance. The formation of 2-(benzylideneamino)-2'-deoxyadenosine as well as a more extensive oxidation product may be explained by the recombination of initial dAdo N(6)-aminyl and benzylidene iminyl radicals. The Formation of 2'-deoxyinosine may be explained by hydrolytic deamination of dAdo N(6)-aminyl radicals. Interestingly, a dimeric product containing two dAdo moieties was identified in the photolysis mixture. The present Studies demonstrate the ability of dAdo N(6)-aminyl radicals to undergo H-abstraction to give dAdo, deamination to give 2'-deoxyinosine, and addition to the adenine moiety to give dimers.

• 出版日期2010-1