Coenzyme Q₁₀ (also known as ubiquinone, ubidecarenone, coenzyme Q, and abbreviated at times to CoQ₁₀, CoQ, Q10, or Q) is a benzoquinone, where Q refers to the quinone chemical group, and 10 refers to the isoprenyl chemical subunits.

This oil-soluble vitamin-like substance is present in most eukaryotic cells, primarily in the mitochondria. It is a component of the electron transport chain and participates in aerobic cellular respiration, generating energy in the form of ATP. Ninety-five percent of the human body’s energy is generated this way. Therefore, those organs with the highest energy requirements – such as the heart and the liver – have the highest CoQ₁₀ concentrations.

History

Coenzyme Q was first discovered by professor Fred L. Crane and colleagues at the University of Wisconsin-Madison Enzyme Institute in 1957. In 1958, its chemical structure was reported by Professor Karl Folkers and coworkers at Merck.

Chemical properties

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 to the right 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 (either oxygen may become a free-radical, in this case the top oxygen is shown as such).  

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

Biochemical role

CoQ is found in the membranes of many organelles. Since its primary function in cells is in generating energy, the highest concentration is found on the inner membrane of the mitochondrion. Some other organelles that contain CoQ₁₀ include endoplasmic reticulum, peroxisomes, lysosomes, and vesicles.

Supplementation

Because of its ability to transfer electrons and therefore act as an antioxidant, Coenzyme Q is also used as a dietary supplement. When one is younger the body can synthesize Q₁₀ from the lower-numbered ubiquinones such as Q₆ or Q₈. The elderly and sick may not be able to make enough, thus Q₁₀ becomes a vitamin later in life and in illness.

Mitochondrial disorders

Supplementation of Coenzyme Q₁₀ is a treatment for some of the very rare and serious mitochondrial disorders and other metabolic disorders, where patients are not capable of producing enough coenzyme Q₁₀ because of their disorder. Coenzyme Q₁₀ is then prescribed by a physician.

Migraine headaches

Supplementation of Coenzyme Q₁₀ has been found to have a beneficial effect on the condition of some sufferers of migraine headaches. So far, three studies have been done, of which two were small, did not have a placebo group, were not randomized, and were open-label, and one was a double-blind, randomized, placebo-controlled trial, which found statistically significant results despite its small sample size of 42 patients. Dosages were 150 to 300 mg/day.

Cancer

It is also being investigated as a treatment for cancer, and as relief from cancer treatment side-effects.

Brain health and neurodegenerative diseases

Recent studies have shown that the antioxidant properties of coenzyme Q₁₀ benefit the body and the brain in animal models. Some of these studies indicate that coenzyme Q₁₀ protects the brain from neurodegenerative disease such as Parkinson's, although it does not relieve the symptoms. Dosage was 300 mg per day.

Cardiac arrest

Another recent study shows a survival benefit after cardiac arrest if coenzyme Q₁₀ is administered in addition to commencing active cooling (to 32–34 degrees Celsius).

Blood pressure

There are several reports concerning the effect of CoQ₁₀ on blood pressure in human studies. In a recent meta-analysis of the clinical trials of CoQ₁₀ for hypertension, a research group led by Professor Frank Rosenfeldt (Director, Cardiac Surgical Research Unit, Alfred Hospital, Melbourne, Australia) reviewed all published trials of Coenzyme Q₁₀ for hypertension, and assessed overall efficacy, consistency of therapeutic action, and side-effect incidence. Meta-analysis was performed in 12 clinical trials (362 patients) comprising three randomized controlled trials, one crossover study, and eight open-label studies. The research group concluded that coenzyme Q₁₀ has the potential in hypertensive patients to lower systolic blood pressure by up to 17 mm Hg and diastolic blood pressure by up to 10 mm Hg without significant side-effects.

Lifespan

Studies have shown that low dosages of coenzyme Q₁₀ reduce oxidation and DNA double-strand breaks, and a combination of a diet rich in polyunsaturated fatty acids and coenzyme Q₁₀ supplementation leads to a longer lifespan in rats.

Biosynthesis

The benzoquinone portion of Coenzyme Q₁₀ is synthesized from tyrosine, whereas the isoprene sidechain is synthesized from acetyl-CoA through the mevalonate pathway. The mevalonate pathway is also used for the first steps of cholesterol biosynthesis.

Inhibition by statins and beta blockers

Coenzyme Q₁₀ shares a common biosynthetic pathway with cholesterol. The synthesis of an intermediary precursor of Coenzyme Q₁₀, mevalonate, is inhibited by some beta blockers, blood pressure-lowering medication, and statins, a class of cholesterol-lowering drugs. Statins can reduce serum levels of coenzyme Q₁₀ by up to 40%. Some research suggests the logical option of supplementation with coenzyme Q₁₀ as a routine adjunct to any treatment that may reduce endogenous production of coenzyme Q₁₀, based on a balance of likely benefit against very small risk.

Occurrence in nature

CoQ10 occurs in mackerel and herring fresh heart tissue in concentrations of 105-148 μg/g. In fresh mackerel "red and white tissue," CoQ10 concentrations of 67 and 15 μg/g, respectively, have been reported. In fresh herring tissue, an amount of 15–24 μg/g of CoQ10 has been reported.

CoQ10 Content of various foods:

Food	CoQ10 [μg/g]	Portion of Food [g]	CoQ10 Amount in Portion [mg]
Pork heart	203	120	24
Soybean Oil		100	9.2
Canola Oil		100	7.3
Peanut Oil		100	5.2
Chicken leg	17	120	2.0
Beef heart	41	120	4.8
Sesame seeds Oil		100	3.2

Cooking by frying reduces Q10 content from 14-32%.

References

See also

• Idebenone - synthetic analog with reduced oxidant generating properties

External links

• Coenzyme Q10 general details, treatment methods, and side effects
• An Introduction to Coenzyme Q₁₀ at University of Washington
• Possible Health Benefits of Coenzyme Q₁₀ at Oregon State University
• Study Suggests Coenzyme Q₁₀ Slows Functional Decline in Parkinson's Disease at National Institute of Neurological Disorders and Stroke