Study on the generation and nature of radical species of pterin in acidic media. Spectral analysis and kinetics

RUIZ GUSTAVO T; FERNANDO S. GARCÍA EINSCHLAG

Cubatao

Encuentro; IX ELAFOT, Encuentro Latinoamericano de Fotoquímica y Fotobiología.; 2008

Pterins, heterocyclic compounds widespread in biological systems, participate in relevant biological processes and are able to act as photosensitizers. The participation of pterins in different photobiological processes has been suggested or demonstrated in the past decades, and interest in the photochemistry and photophysics of this group of compounds has subsequently increased. Nevertheless, a systematic study about the reactivity of pterins with radicals, and the nature of pterines radicals generated has been little studied. In this work, we present the formation of pterin¢¥s radicals by reaction with e-aq and C*H2OH radicals generated by pulse radiolysis, pH = 5.5. Since e-sol and C*H2OH have large reduction potentials, i.e., -2.8 V vs NHE for e-sol and -0.92 V vs NHE for C*H2OH, they have been used for the reduction of pterin. The data was collected for time-resolved UV-Vis spectroscopy. In the Figure, the spectrum of the pterin radical obtained as a product of reaction with e-aq is shown. Nature and number of species is discussed as a result of the espectral analysis of data.