Ubiquinone - Definition

Coenzyme Q (CoQ), also known as ubiquinone or ubiquinol, is a biologically active quinone with an isoprenoid side chain, related in structure to vitamin K and vitamin E.

The oxidized structure of CoQ, or Q, is given here:

The various kinds of Coenzyme Q can be distinguished by the number of isoprenoid side chains they have. The most common CoQ in human mitochondria is Q10. The image above has three isoprenoid units and would be called Q3.

If Coenzyme Q is reduced by one equivalent, the following structure results, a ubisemiquinone, and is denoted QH. Note the free radical on one of the ring oxygens.

If Coenzyme Q is reduced by two equivalents, the compound becomes a ubiquinol, denoted QH₂:

CoQ is found in the membranes of endoplasmic reticulum, peroxisomes, lysosomes, vesicles and notably the inner membrane of the mitochondrion where it is an important part of the electron transport chain, there it passes reducing equivalents to acceptors such as Coenzyme Q - cytochrome c reductase:

CoQH₂+ 2 Fe⁺³-cytochrome c → CoQ + 2 Fe⁺²-cytochrome c

Because of its ability to transfer electrons and therefore act as an antioxidant, Coenzyme Q has become a fashionable dietary supplement.

Supplementation of Coenzyme Q10 has been found to have a beneficial effect on the condition of some sufferers of migraines. It is also being investigated as a treatment for cancer, and as relief from cancer treatment side effects.

Recent studies have suggested that Coenzyme Q10 may act as an important antioxidant in the body and the brain. Some of these studies have indicated that Coenzyme Q10 may protect the brain from neurodegenerative disease such as Parkinsons and also from the damaging side effects of a transient ischemic attack (stroke) in the brain.

External links

• An Introduction to Coenzyme Q10 (http://faculty.washington.edu/~ely/)
• Vitamin Q - Herbs & Supplements - Drug Library - DrugDigest (http://www.drugdigest.org/DD/DVH/HerbsWho/0,3923,4021%7CVitamin+Q,00.html)
• Co-Q10 Energizes the Heart and Brain (http://exchange.healthwell.com/nutritionsciencenews/nsn_backs/Jul_99/nutrientreview.cfm)
• Possible Health Benefits of Coenzyme Q10 (http://lpi.oregonstate.edu/f-w02/coenzymeq10.html)
• Coenzyme Q10 administration increases brain mitochondrial concentrations and exerts neuroprotective effects (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9671775&dopt=Abstract)
• Study Suggests Coenzyme Q10 Slows Functional Decline in Parkinson's Disease (http://www.ninds.nih.gov/news_and_events/press_releases/pressrelease_parkinsons_coenzymeq10_101402.htm)
• Oral coenzyme Q10 administration prevents the development of ischemic brain lesions in a rabbit model of symptomatic vasospasm (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=9341938&dopt=Abstract)