Coenzyme Q10 (CoQ10) is also referred to as ubiquinone because it can be found in almost all eukaryotic cells. CoQ10 embedded in the inner mitochondrial membrane is an essential component of the electron transport chain and plays a role in the ATP-producing oxidative phosphorylation. CoQ10 is also a powerful lipid-soluble antioxidant protecting cell membranes and lipoproteins. CoQ10 is present in the plasma in both the reduced (ubiquinol) and oxidized (ubiquinone) forms. The reduced form of CoQ10 is the only endogenously synthesized lipophilic antioxidant and as such, serves to protect biological membranes against oxidation as well as inhibiting the peroxidation of lipoproteins in the circulation. Reduced CoQ10 in plasma may also have a role recycling vitamin E (alpha-tocopherol).
