Oxidative stress may be broadly defined as an imbalance between oxidant production and the antioxidant capacity of the cell to prevent oxidative injury; it is a condition believed to be involved in a large number of human diseases including atherosclerosis, cancer and neurodegenerative neuroinflammatory diseases, and also in aging. The situation of oxidative stress results in the production of O2 metabolites known as Reactive Oxygen Species (ROS) due to their enhanced reactivity compared to molecular oxygen; the most common are the superoxide anion (O2-.), hydrogen peroxide (H2O2), and the highly reactive hydroxyl radical (OH.). In order to protect themselves from ROS damage cells possess several antioxidant enzymes, such as superoxide dismutase (SOD), catalase and glutathione peroxidase, but also low molecular weight antioxidants like vitamin C and vitamin E.Much evidence suggests that ROS are not only injurious by-products of cellular metabolism but also essential participants in cell signaling and regulation and it is now clear that small amounts of ROS act as messenger molecules in cell signal transduction pathways. The plasma membrane of eukaryotic cells in particular contains a variety of different ROS-producing oxidases and reductases, of which the best characterized are the superoxide-producing NADPH oxidases. It has been known for many years that these membrane redox activities can be changed rapidly by various hormones and growth factors, but the molecular mechanisms involved and the physiological importance of this phenomenon have only recently begun to be unveiled. We here summarize the state of the art on membrane-based ROS signaling in the pathways of several hormones, mainly insulin and thyroid hormones. The apparent paradox of ROS being essential biomolecules in the regulation of cellular functions, but also toxic by-products of metabolism, may be important for the pharmacological application of natural and synthetic antioxidants. We report results on the capability of coumarins, flavonoids and other polyphenols to modulate the ROS production by some hormones and the signal transduction pathways involved.
Incerpi, S., PEDERSEN JENS, Z., DE VITO, P., Kumar, A., Prasad, A., RAJ HANUMANTHARAO, G., et al. (2008). Biological activity of natural and synthetic antoxidants in L-6 myoblasts in culture: redefining the role of Reactive Oxygen Species. In Indo -Italian seminar on Green Chemistry and Natural Products (pp.IL-7).