Solvent Effects on the Reactivity of Fluorenyl Nitrenium Ion with DNA-Like Probes

A MCCLELLAND, ROBERT; AL POSTIGO *

BIOPHYSICAL CHEMISTRY

ELSEVIER

Lugar: USA. http://dx.doi.org/10.1016/j.bpc.2005.09.014. ISSN: 0301-4622; Año: 2006 vol. 119 p. 213 - 218

0301-4622

Laser Flash Photolysis (LFP) experiments carried out on 2-azidofluorene in aqueous systems generate 2-fluorenyl nitrenium ion (kmax= 450nm) which decays with first order rate constant and is quenched with 2V-deoxyguanosine originating an intermediate, namely the C8 adduct of 2-fluorenyl nitrenium ion, with bimolecular rate constant in the order of 1.3109 M1 s1 in pure water. This intermediate very likely mimics theintermediate formed from carcinogens (i.e.: arylnitrenium ions formed through metabolic activation pathways from aminoaromatic substrates) andDNA rests in vivo. Solvent effects demonstrate and support the further stabilization of this intermediate (with respect to fluorenyl nitrenium ion)through hydrogen bonding as compared to other probe systems, and accounts for the enhanced metabolic carcinogenecity observed for this type ofcompounds. Diverse solvent systems, such as mixtures of water with acetonitrile, 1,1,1-trifluoroethanol, and 1,1,1,3,3,3-hexafluoroisopropanol,are used to interpret solvent – complex interactions.