ubikinon

Ubikinon, also spelled ubiquinone, is a lipid-soluble benzoquinone that participates in cellular energy production. In humans it is best known as coenzyme Q10 (CoQ10), a component of the mitochondrial electron transport chain and a molecule with antioxidant properties. The name reflects its ubiquity in living organisms.

Chemistry: Ubikinone features a benzoquinone ring with a long hydrophobic isoprenoid tail that anchors it within membranes. The length of the tail varies by organism; in humans the predominant form is Q10. Ubikinone cycles between an oxidized form (ubiquinone) and a reduced form (ubiquinol).

Biological role: In the inner mitochondrial membrane, ubiquinone transfers electrons from Complex I and Complex II to Complex III, supporting ATP synthesis. In its reduced state, ubiquinol acts as an antioxidant, protecting lipids and proteins from oxidative damage and regenerating other antioxidants.

Biosynthesis and dietary sources: Ubiquinone is synthesized endogenously through a multi-step pathway involving isoprenoid tail formation; it is also obtained from the diet in meats, fish, and some vegetables. Supplemental CoQ10 is widely available in two forms, ubiquinone and ubiquinol; both are absorbed, with some evidence suggesting ubiquinol absorption may be enhanced in older adults.

Medical and research context: Supplementation is studied for potential benefits in aging, mitochondrial disorders, and statin-associated depletion. Clinical results are variable and do not establish a universal therapeutic effect. Side effects are generally mild, including gastrointestinal upset or headaches; serious adverse events are uncommon.

History and terminology: The term ubiquinone derives from ubiquity across life. The variant spelling ubikinon appears in some texts or transliterations. The compound was identified in the mid- to late-20th century during investigations of mitochondrial respiration.