PHOTOCHEMICAL BEHAVIOUR OF FISETIN AND FISETIN-COPPER(II)

MUÑOZ, VANESA A.; DIMARCO PALENCIA, FRIDA C. D..; MISKOSKI, SANDRA; FERRARI, GABRIELA V.; GARCÍA, NORMAN A.; MONTAÑA, M. PAULINA

Congreso; XIII ENCUENTRO LATINOAMERICANO DE FOTOQUÍMICA Y FOTOBIOLOGÍA; 2017

The Riboflavin (Rf)-sensitized photoirradiation Fis and Fis-Cu(II) at H2O/EtOH 70:30 v/v medium produced spectral changes that can be attributed to transformations in both substrates. The oxygen uptake in presence and absence of specific quencher of reactive oxygen species (ROS) made evident the interaction between Fis and H2O2, showed by the decrease of the O2 consumption rate in presence of catalase, whereas in the case of Fis-Cu(II) complex the experimental results allow to confirm the participation of the O2?- species in the oxidative process, but no significant evidence of singlet molecular oxygen (O2(1Δg)) interaction was observed. Nevertheless, on the basis of our previous investigations where this ROS usually plays a rol in the photooxidative mechanism of flavonoids, the rate constant for the overall interaction with O2(1Δg), kt, was determined through a Stern-Volmer treatment (see values in the table). The phosphorescence quenching experiments demonstrated the existence of a O2(1Δg)-Fis and Fis-Cu(II) interaction.