Reactive Oxygen Species (ROS)

    Reactive oxygen species are a group of molecules derived from molecular oxygen that are formed during the process of aerobic respiration. Although an overabundance of reactive oxygen species can be damaging to cells, these molecules also have a fundamental role in normal physiology as functional signaling molecules.

    Summary

    Reactive oxygen species (ROS) are a group of molecules derived from molecular oxygen that are formed during the process of aerobic respiration and cellular energy production. ROS are so named due to their highly reactive nature. Several species of ROS exist, including hydrogen peroxide (H2O2), superoxide (O2−), peroxynitrite (ONOO−), and hydroxyl radical (•OH). ROS can be subdivided into free radicals (molecules with at least one unpaired electron) and nonradicals (no unpaired electrons).

    Although they’re often blamed for promoting cellular damage and inflammation and contributing to metabolic and cardiovascular diseases, it is well understood that ROS also play a fundamental role in normal physiology as functional signaling molecules. ROS are produced endogenously by our mitochondria, whereas exogenous sources of ROS production include exposure to nutrients, drugs, toxins, pollutants, and radiation. When levels of ROS exceed the body’s ability to neutralize them to physiologic levels, this can lead to a process known as oxidative (dis)stress.