Free Radical

A reactive molecule or atom with one or more unpaired electrons, making it highly chemically reactive. In biological systems, free radicals (including reactive oxygen species such as superoxide, hydroxyl radical, and hydrogen peroxide) are produced during normal cellular metabolism and in response to environmental stressors. Antioxidants (including glutathione, Vitamin C, Vitamin E) neutralise free radicals by donating electrons, reducing oxidative damage to proteins, lipids, and DNA. Excessive free radical production relative to antioxidant capacity is termed oxidative stress.