Figure 2.

Schematic representation of the generation and the effects of free radicals within the mitochondria. The leakage of electrons from the mitochondrial ETC at complexes I and III results in the formation of superoxide anion. The high reactivity of this molecule evokes a harmful cascade mechanism including the formation of reactive oxygen and nitrogen species. The cascade mechanism deteriorates the functional groups of major components of all kinds of biomolecules (carbohydrates, lipids, proteins, and nucleic acids). In case of pronounced electron leakage or deficient antioxidant protection, a vicious circle of mitochondrial dysfunction develops.