Ubiquinol-10 is a ubiquinol in which the polyprenyl substituent is decaprenyl. It has a role as a metabolite and a biomarker. It is a polyprenylhydroquinone and an ubiquinol.Ubiquinol is a reduced form of coenzyme Q10 (CoQ10; ), which exists in three redox states: fully oxidized (CoQ10/ubiquinone), partially reduced (semiquinone/ubisemiquinone), and fully reduced (ubiquinol). CoQ10 acts as an electron shuttle in the electron transport chain via its reduction to ubiquinol between mitochondrial complexes I and II, also known as NADH dehydrogenase and succinate dehydrogenase, respectively, and mitochondrial complex III, also known as cytochrome bc1 complex.