Photosensitization of 2´-deoxyadenosine-5´-monophosphate by pterin

PETROSELLI GABRIELA; ERRA BALSELLS ROSA; CABRERIZO FRANCO M.; LORENTE CAROLINA; CAPPARELLI ALBERTO L.; BRAUN ANDRÉ M.; OLIVEROS ESTHER; THOMAS ANDRÉS H.

Organic & Biomolecular Chemistry (Royal Society of Chemistry)

Royal Society of Chemistry

Año: 2007 vol. 5 p. 2792 - 2799

1477-0539

UV-A radiation (320–400 nm) induces damages to the DNA molecule and its components through photosensitized reactions. Pterins, heterocyclic compounds widespread in biological systems, participate in relevant biological processes and are able to act as photosensitizers. We have investigated the photosensitization of 2-deoxyadenosine-5-monophosphate (dAMP) by pterin (PT) in aqueous solution under UV-A radiation. The effect of pH was evaluated, the participation of oxygen was investigated and the products analyzed. Kinetic studies revealed that the reactivity of dAMP towards singlet oxygen (1O2) is very low and that this reactive oxygen species does not participate in the mechanism of photosensitization, although it is produced by PT upon UV-A excitation. In contrast, analysis of irradiated solutions by means of electrospray ionization mass spectrometry strongly suggested that 8-oxo-7,8-dihydro-2-deoxyadenosine-5-monophosphate (8-oxo-dAMP) was produced, indicating that the photosensitized oxidation takes place via a type I mechanism (electron transfer).