Superoxide Formation in Cardiac Mitochondria and Effect of Phenolic Antioxidants

Since mitochondria are the main cellular source of reactive oxygen species, it is important to study the effect of dietary phenolic compounds on the level of ROS in these organelles. Using the EPR spectroscopy and TIRON probe, the ability of the investigated phenols (quercetin, rutin, caffeic acid, curcumin, and resveratrol) to scavenge superoxide anion radicals generated by isolated heart mitochondria of Wistar rats under variable oxygen partial pressure was studied. It was shown that during a 10 min incubation, caffeic acid in concentrations of 10–500 μM most effectively scavenged superoxide radicals formed in the complex III of the mitochondrial respiratory chain. A comparable antioxidant effect of rutin under these experimental conditions was observed at higher concentrations of 1–10 mM. The antioxidant activity of quercetin in the concentration range of 10–500 μM during the first minutes of incubation was higher than that of caffeic acid. Of the phenolic compounds studied, curcumin had the least effect on the superoxide radicals.