Antioxidant properties of 4-quinolones and structurally related flavones

Abstract

Neurodegenerative disorders are frequently associated with increased oxidative damage to the brain as a result of free radicals produced by cellular respiration. The onset and progression of neurodegeneration may therefore be curbed by exogenous hydrogen-donating antioxidant moieties such as the naturally occurring flavonoids. A series of 2-phenylquinolin-4(1H)-ones was synthesised and displayed moderate to high antioxidant activity when compared to structurally related flavones and quinolines. Activity of the hydroxy-2-phenylquinolin-4(1H)-ones (8–10) was established in reducing ferrous ions and diminishing hydrogen peroxide and hydroxyl radical production, in the FRAP (1.41–97.71% Trolox® equivalents), ORAC (9.18–15.27 μM Trolox® equivalents at 0.001 mM) and TBARS (0.05–0.72 nmol MDA/mg tissue) assays, respectively. The results indicated that the additional hydrogen donating groups on the synthesised 2-phenylquinolin-4(1H)-one series increased antioxidant activity.