Coenzyme Q10

  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 vitamin-like substance is, by nature, present in all human cells and responsible for the production of the body’s own energy. In each human cell, food energy is converted into energy in the mitochondria with the aid of CoQ₁₀. Ninety-five percent of all the human body’s energy requirements (ATP) is converted with the aid of CoQ₁₀.^[1][2] Therefore, those organs with the highest energy requirements – such as the heart, the lungs, and the liver – have the highest CoQ₁₀ concentrations.^[3][4][5]

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History

Coenzyme Q was first discovered by professor Fred L. Crane and colleagues at the University of Wisconsin-Madison Enzyme Institute in 1957.^[6][7] In 1958, its chemical structure was reported by Professor Karl Folkers and coworkers at Merck.^[8][7] For his discovery of the significant part played by CoQ₁₀ in energy production, the British scientist Peter D. Mitchell was awarded the Nobel Prize for chemistry in 1978.

Chemical properties

Biochemical role

  CoQ is found in the membranes of endoplasmic reticulum, peroxisomes, lysosomes, vesicles, and 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 - oxidoreductase:

CoQH₂+ 2 Fe^III-cytochrome c → CoQ + 2 Fe^II-cytochrome c

CoQ is also essential in the formation of the apoptosome, along with other adapter proteins. The loss of trophic factors activates pro-apoptotic enzymes, causing the breakdown of mitochondria.

Antioxidant role of CoQ₁₀ in the body

Apart from being a cofactor in the mitochondrial electron transport chain, CoQ₁₀ in its reduced form (ubiquinol or CoQ₁₀ H₂) serves as an important antioxidant in both mitochondria and lipid membranes, where it protects the body's cells in their battle against the destructive effects of free-radicals. In human LDL, it affords protection against the oxidative modifications of LDL themselves, thus lowering their atherogenic potency.^[9] CoQ₁₀ is essential in vitamin E regeneration. Ubiquinol inhibits protein and lipid oxidation in cell membranes, and helps to minimize oxidative injury to DNA.^[10] CoQ₁₀ is an integral part of the respiratory chain and thereby located exactly where the free-radicals are generated, in the mitochondria. These endogeneously-produced free-radicals are considered an import factor of the aging process.^[11]

Supplementation

Because of its ability to transfer electrons and therefore act as an antioxidant, Coenzyme Q is also used as a dietary supplement. Young people are able to make Q₁₀ from the lower-numbered ubiquinones such as Q₆ or Q₈.^{[citation needed]} The sick and elderly may not be able to make enough, thus Q₁₀ becomes a vitamin later in life and in illness.^{[citation needed]}

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.^[12]

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,^[13] and one was a double-blind, randomized, placebo-controlled trial, which found statistically significant results despite its small sample size of 42 patients.^[14] 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.^[15]

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.^[16] Some of these studies indicate that Coenzyme Q₁₀ protects the brain from neurodegenerative disease such as Parkinson's,^[17] although it does not relieve the symptoms.^[18] 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).^[19]

Blood pressure

There are several reports concerning the effect of CoQ₁₀ on blood pressure in human studies.^[20] In a recent meta-analysis of the clinical trials of CoQ₁₀ for hypertension, a research group led by Professor FL Rosenfeldt (from the 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.^[21]

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 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,^[22] and statins, a class of cholesterol-lowering drugs.^[23] Statins can reduce serum levels of coenzyme Q₁₀ by up to 40%.^[24] 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.^[25][26]

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.^[27]

CoQ10 Content of various foods:^[28]

References