ELECTRON TRANSFER PROCESSES INDUCED BY THE TRIPLET STATE OF PTERINS IN AQUEOUS SOLUTIONS

M. LAURA DÁNTOLA; MARIANA VIGNONI; CONSTANZA GONZÁLEZ; CAROLINA LORENTE; PATRICIA VICENDO; ESTHER OLIVEROS; ANDRÉS H. THOMAS

Ferrara

Congreso; XXIII IUPAC Symposium on Photochemistry.; 2010

IUPAC

Pterins (Pt), heterocyclic compounds widespread in living systems, participate in relevant biological processes, such as metabolic redox reactions. Under UV-A excitation (320–400 nm), pterins can fluoresce, undergo photooxidation, generate reactive oxygen species (ROS)[[i]] and photoinduce oxidation of biomolecules through electron transfer mechanisms.[[ii],[iii]] We have investigated the electron transfer pathways initiated by excited states of pterin and 6-methylpterin. The experiments were carried out in aqueous solutions under continuous UV-A irradiation and ethylenediaminetetraacetic acid (EDTA) was used as an electron donor. The reactions were followed by UV/Vis spectrophotometry, HPLC and an enzymatic method for H2O2 determination. The formation of the superoxide anion (O2•‒) was investigated by electron paramagnetic resonance-spin trapping. [[i]] Lorente, C.; Thomas, A. H.; Acc. Chem. Res.2006, 39, 395-402. [[ii]]Petroselli, G.; Erra-Balsells, R.; Cabrerizo, F. M.; Lorente, C.; Capparelli, A. L.; Braun, A. M.; Oliveros, E.; Thomas, A. H.; Org. Biomol. Chem. 2007, 5, 2792-2799. [[iii]] Petroselli, G.; Dántola, M. L.; Cabrerizo, F. M.; Capparelli, A. L.; Lorente, C.; Oliveros, E.; Thomas, A. H.; J. Am. Chem. Soc. 2008, 130, 3001-3011.