Abstract
Naringenin and quercetin are considered antioxidant compounds with promising activity against oxidative damage in human cells. However, no reports have described their effects on reactive oxygen species (ROS) production by phagocytes during microbicidal activity. Thus, the present study evaluated the effects of naringenin and quercetin on ROS production, specifically hypochlorous acid (HOCl), and their involvement in the microbicidal activity of neutrophils. Naringenin and quercetin inhibited HOCl production through different systems, but this inhibition was more pronounced for quercetin, even in the cell-free systems. With regard to the microbicidal activity of neutrophils, both naringenin and quercetin completely inhibited the killing of Staphylococcus aureus. Altogether, these data indicate that the decrease in the oxidant activity of neutrophils induced by these compounds directly impaired the microbicidal activity of neutrophils. Naringenin and quercetin exerted their effects by controlling the effector mechanisms of ROS production, with both positive and negative effects of these antioxidant agents in oxidative stress conditions and on ROS in the microbicidal activity of phagocytes. The present results challenge the traditional view of antioxidants as improvers of pathological conditions.
Highlights
Accumulating evidence indicates the involvement of reactive oxygen species (ROS) in different physiological functions and various cell signaling processes, including reproduction, cell migration, stem cell proliferation, neurogenesis, and phagocytosis [1,2,3,4,5]
Numerous compounds with potential antioxidant effects and promising activity against many human diseases associated with oxidative damage have been studied over the past years [23, 24]
The microbicidal activity of phagocytes is well known to depend on ROS, and hypochlorous acid (HOCl) plays an important role in this process [25]
Summary
Accumulating evidence indicates the involvement of reactive oxygen species (ROS) in different physiological functions and various cell signaling processes, including reproduction, cell migration, stem cell proliferation, neurogenesis, and phagocytosis [1,2,3,4,5]. Depending on the intracellular concentration of ROS, they can contribute to both physiological and pathological conditions. The long-term exposure of cells to enhanced levels of ROS is involved in the pathogenesis of many human diseases, including chronic inflammation, neurodegenerative disorders, and some cancers, by damaging essential molecules, such as lipids, proteins, and DNA [6,7,8,9]. The literature presents various compounds obtained from plants with promising antioxidant effects, few studies have examined the side effects of these substances on physiological functions that depend on ROS
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