CoQ10

Coenzyme Q10 (ubiquinone) is a lipid-soluble quinone molecule endogenously synthesised via the mevalonate pathway — the same pathway targeted by statin drugs — and functions as the mobile electron carrier between Complexes I/II and Complex III of the mitochondrial respiratory chain. This electron shuttle reaction is the central mechanism of oxidative phosphorylation, generating the proton gradient that drives ATP synthase and produces approximately 90% of cellular ATP. In the oxidised form, CoQ10 accepts electrons from NADH and FADH2; after electron transfer it becomes ubiquinol, which simultaneously serves as a potent lipid-phase antioxidant protecting mitochondrial inner membrane phospholipids from peroxidative damage. Endogenous CoQ10 synthesis declines with age and is significantly depleted by statin medications, making supplementation clinically important for these populations.