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Antioxidant properties and free radical-scavenging reactivity of a family of hydroxynaphthalenones and dihydroxyanthracenones

2007; Elsevier BV; Volume: 15; Issue: 22 Linguagem: Inglês

10.1016/j.bmc.2007.07.013

1464-3391

Jorge Rodríguez, Claudio Olea‐Azar, Cristina Cavieres, Ester Norambuena, Tomás Delgado‐Castro, Jorge Soto‐Delgado, Ramiro Araya‐Maturana,

Photochemistry and Electron Transfer Studies

This study was undertaken to investigate the free radical-scavenging and antioxidant activities of various structurally related hydroquinones including hydroxynaphthalenones and dihydroxyanthracenones. Electron spin resonance spectroscopy and spin trapping techniques were used to evaluate the ability of hydroquinones to scavenge hydroxyl, diphenylpicrylhydrazyl, and galvinoxyl radicals. In addition, the oxygen radical absorbing capacity assay using fluorescein (ORAC-FL) was used to obtain the relative antioxidant capacity of these radicals. The rate constants of the first H atom abstraction by 2,2-diphenyl-2-picrylhydrazyl (k2), were obtained under pseudo-first-order conditions. The free radical-scavenging activities and k2 values discriminate well between hydroxynaphthalenones and dihydroxyanthracenones, showing that the latter have better antioxidant properties. The aforementioned experimental data agree with quantum-chemical results demonstrating the relevance of intramolecular H bonding to radical-scavenging activities.