Reactive oxygen species (ROS) are short-lived (10-9 s) reactive molecules belonging to the class of free radicals, which are derived from oxygen and characterised by the presence of one or more unpaired electrons in their outer shell. Due to their unstable chemical structure, they attack nearby organic molecules, such as lipids, proteins and DNA, in order to reach a balanced state. The most important ROS include superoxide anion (O −. 2), hydroxyl radical (OH .), peroxyl radicals (ROO .), alkoxyl radicals (RO .), organic hydroperoxides (ROOH) and hydrogen peroxide (H 2 O 2) (Aitken, 2017). Although the latter could be considered as a nonradical oxidant, H 2 O 2 can react with ferrous ions and enhance the synthesis of OH. through the Fenton and the Haber-Weiss reactions. Additionally, nitrogen-based free radicals, such as peroxynitrite (ONOO-) and nitric oxide (NO .), are also a subclass of ROS. The most important source of endogenous free radicals is mitochondria, the organelles responsible for cellular energy production in the form of adenosine triphosphate (ATP). In the inner mitochondrial membrane, different substrates are oxidised and reduced through the electron transport chain complex, generating an electron flux which terminates with ATP synthesis and the reduction of molecular oxygen to water. Although this process is highly efficient, about 1%-2% of oxygen is reduced to superoxide by complex I-and III-mediated single electron transfer (Fukai & Ushio-Fukai, 2011). Non-mitochondrial sources of ROS include peroxisomal β-oxidation,