Spectroscopic determination of deprotonation constants of flavonoids

ANALÍA NATALÍ ARIAS; GUSTAVO CÉLIZ

Buenos Aires

Congreso; VI International Conference on Polyphenols and Health; 2013

Facultad de Farmacia de la UBA

Although the mechanisms by which flavonoids exert benefical pharmacological effects are not fully understood, is accepted that these result from the radical scavenging ability to delay the oxidative stress. The chelating capacity of flavonoids, which has a crucial role in oxidative stress and in the treatment of metal overload diseases, is largely dependent on the number, position, and dissociation of their hydroxyl groups. Moreover, the dependence between the acidity constants of flavonoids can explain changes in the solubility and membrane permeability in biological processes. Therefore, the acidity constant of the hydroxyl groups is an important parameter controlling both, the anti-oxidative capacity and the chelating capacity of flavonoids. In this work, the full deprotonation of flavanones containing the aglycones naringenin and hesperetin was studied in aqueous solutions by chemometrics methods obtaining UV-VIS spectra at different pH?s. We found that compounds with glycoside moieties are not significantly different but are significantly different between aglycones and glycosides. At physiological pH?s in all case the neutral form and the first deprotonated form are the mainly species.