Pro‐Oxidant Influence of Quercetin Supplementation in Saccharomyces cerevisiae

ABSTRACT How could quercetin exert a pro‐survival phenotype (antioxidant) and simultaneously be toxic for eukaryotic cells? The redox capacity of quercetin may explain its antioxidant and toxic effects, based on the idea that quercetin impairs the electron transport chain, affecting ATP production and forming quercetin‐derived free radicals. Herein, we provide evidence that quercetin supplementation: (1) depolarizes the mitochondrial membrane and augments the ADP/ATP ratio; (2) increases superoxide anion cellular levels; (3) changes the cellular response to H 2 O 2 challenge associated with the antioxidant cellular response; and (4) sensitizes the cellular response to lipoperoxidation challenge. These events suggest that the quercetin pro‐oxidant effect is related to mitochondrial respiration dysfunction and could induce cellular antioxidant response.