Coenzyme Q10
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[[Image:Ubiquinone.png|thumb|250px|Ubiquinone]]
'''Coenzyme Q<sub>10</sub>''' (also known as ubiquinone, ubidecarenone, coenzyme Q, and abbreviated at times to CoQ<sub>10</sub>, CoQ, Q10, or Q) is a [[benzoquinone]], where '''Q''' refers to the [[quinone]] chemical group, and '''10''' refers to the [[isoprene|isoprenyl]] chemical subunits.
This [[vitamin]]-like substance is, by nature, present in most human cells except red blood cells and eye lens cells (no mitochondria) and is 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 CoQ<sub>10</sub>. Ninety-five percent of all the human body’s energy requirements ([[adenosine triphosphate|ATP]]) is converted with the aid of CoQ<sub>10</sub>.<ref>Ernster L, Dallner G: Biochemical, physiological and medical aspects of ubiquinone function. Biochim Biophys Acta 1271: 195-204, 1995</ref><ref>Dutton PL, Ohnishi T, Darrouzet E, Leonard, MA, Sharp RE, Cibney BR, Daldal F and Moser CC. 4 Coenzyme Q oxidation reduction reactions in mitochondrial electron transport (pp 65-82) in Coenzyme Q: Molecular mechanisms in health and disease edited by Kagan VE and Quinn PJ, CRC Press (2000), Boca Raton</ref> Therefore, those organs with the highest energy requirements – such as the heart and the liver – have the highest CoQ<sub>10</sub> concentrations.<ref>Okamoto, T.et al (1989) Interna.J.Vit.Nutr.Res.,59,288-292</ref><ref>Aberg,F.et al (1992)Archives of Biochemistry and Biophysics, 295, 230-234</ref><ref>Shindo, Y., Witt, E., Han, D., Epstein, W., and Packer, L., Enzymic and non-enzymic antioxidants in epidermis and dermis of human skin, Invest. Dermatol., 102 (1994) 122-124.</ref>
==History==
Coenzyme Q was first discovered by professor [[Fred L. Crane]] and colleagues at the [[University of Wisconsin-Madison]] Enzyme Institute in [[1957]].<ref>{{cite journal |author=Crane F, Hatefi Y, Lester R, Widmer C |title=Isolation of a quinone from beef heart mitochondria |journal=Biochim Biophys Acta |volume=25 |issue=1 |pages=220–1 |year=1957 |pmid=13445756 |doi=10.1016/0006-3002(57)90457-2}}</ref><ref name="washington">Peter H. Langsjoen, "[http://faculty.washington.edu/~ely/coenzq10.html Introduction of Coezyme Q10]"</ref> In [[1958]], its chemical structure was reported by Professor [[Karl Folkers]] and coworkers at [[Merck & Co.|Merck]].<ref>Wolf DE, Hoffman CH, Trenner NR, Arison BH, Shunk CH, Linn BD, McPherson JF, and Folkers K.
Structure studies on the coenzyme Q group. J Am Chem Soc 1958: 80:4752.</ref><ref name="washington" />
==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 [[isoprene|isoprenoid]] [[side-chain]]s they have. The most common CoQ in human [[mitochondria]] is Q<sub>10</sub>. The image to the right has three [[isoprene|isoprenoid]] units and would be called Q<sub>3</sub>. [[Image:Ubiquinone3.png|center|300px]]
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). [[Image:Ubisemiquinone3.png|center|300px]]
If Coenzyme Q is reduced by two equivalents, the compound becomes a '''ubiquinol''', denoted '''QH<sub>2</sub>''': [[Image:ubiquinol3.png|center|300px]]
==Biochemical role==
[[Image:ETC.PNG|thumb|300px|[[Electron transport chain]] ("UQ" visible in green near center.)]]
CoQ is found in the [[biological membrane|membranes]] of [[endoplasmic reticulum]], [[peroxisome]]s, [[lysosome]]s, [[vesicle (biology)|vesicle]]s, 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 reductase|Coenzyme Q: cytochrome c - oxidoreductase]]:
:CoQH<sub>2</sub>+ 2 Fe<sup>III</sup>-cytochrome c → CoQ + 2 Fe<sup>II</sup>-cytochrome c
CoQ is also essential in the formation of the [[apoptosome]], along with other adapter proteins. The loss of trophic factors activates pro-[[apoptosis|apoptotic]] enzymes, causing the breakdown of mitochondria.
==Supplementation==
Because of its ability to transfer electrons and therefore act as an [[antioxidant]], Coenzyme Q is also used as a [[dietary supplement]]. When you are younger the body can synthesize Q<sub>10</sub> from the lower-numbered ubiquinones such as Q<sub>6</sub> or Q<sub>8</sub>.{{Fact|date=February 2007}} The sick and elderly may not be able to make enough, thus Q<sub>10</sub> becomes a [[vitamin]] later in life and in illness.{{Fact|date=April 2007}}
===Mitochondrial disorders===
Supplementation of Coenzyme Q<sub>10</sub> is a treatment for some of the very rare and serious [[mitochondrial disease|mitochondrial disorder]]s and other [[metabolic disorder]]s, where patients are not capable of producing enough coenzyme Q<sub>10</sub> because of their disorder. Coenzyme Q<sub>10</sub> is then prescribed by a physician.<ref>{{cite journal | last = Berbel-Garcia | first = A. | coauthors = ''et al.'' | title = Coenzyme Q 10 improves lactic acidosis, strokelike episodes, and epilepsy in a patient with MELAS | journal = Clinical Neuropharmacology | volume = 27 | year = 2004 | month = July | pages = 187–191 | pmid = 15319706 | accessdate = 2006-12-01 | doi = 10.1097/01.wnf.0000137862.67131.bf }}</ref>
===Migraine headaches===
Supplementation of Coenzyme Q<sub>10</sub> 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 trial|open-label]],<ref>{{cite journal |author=Rozen T, Oshinsky M, Gebeline C, Bradley K, Young W, Shechter A, Silberstein S |title=Open label trial of coenzyme Q10 as a migraine preventive |journal=Cephalalgia |volume=22 |issue=2 |pages=137–41 |year=2002 |pmid=11972582 |url = http://www.blackwell-synergy.com/doi/full/10.1046/j.1468-2982.2002.00335.x |doi=10.1046/j.1468-2982.2002.00335.x}}</ref> and one was a double-blind, randomized, placebo-controlled trial, which found statistically significant results despite its small sample size of 42 patients.<ref>{{cite journal |author=Sándor PS, et al.|title=Efficacy of coenzyme Q10 in migraine prophylaxis: A randomized controlled trial |journal=Neurology |volume=64 |pages=713–715 |year=2005 |url = http://www.neurology.org/cgi/content/abstract/64/4/713|pmid=15728298|doi=10.1212/01.WNL.0000151975.03598.ED|doi_brokendate=2008-06-26}}</ref> 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.<ref>
Katsuhisa Sakano, Mami Takahashi, Mitsuaki Kitano, Takashi Sugimura, Keiji Wakabayashi: Suppression of Azoxymethane-induced Colonic Premalignant Lesion Formation by Coenzyme Q10 in Rats. Asian Pacific J Cancer Prev, 7, 599-603, 2006
</ref>
===Brain health and neurodegenerative diseases===
Recent studies have shown that the antioxidant properties of Coenzyme Q<sub>10</sub> benefit the body and the [[brain]] in animal models.<ref>{{cite journal | last = Matthews | first = R. T. | coauthors = ''et al.'' | title = Coenzyme Q10 administration increases brain mitochondrial concentrations and exerts neuroprotective effects | journal = PNAS | volume = 95 | year = 1998 | month = July | pages = 8892–8897 | url = http://intl.pnas.org/cgi/content/abstract/95/15/8892 | accessdate = 2006-12-01 | doi = 10.1073/pnas.95.15.8892 | pmid = 9671775 }}
</ref> Some of these studies indicate that Coenzyme Q<sub>10</sub> protects the brain from neurodegenerative disease such as [[Parkinson's]],<ref>''Biol Signals Recept. 2001 May-Aug;10(3-4):224-53''</ref> although it does not relieve the symptoms.<ref name='NCT00180037'> {{cite web|url=http://tools.wikimedia.de/~magnus/makeref.php |title=Randomized, Double-blind, Placebo-Controlled Trial on Symptomatic Effects of Coenzyme Q10 in Parkinson Disease |last=Alexander Storch, MD; Wolfgang H. Jost, MD; Peter Vieregge, MD; Jörg Spiegel, MD; Wolfgang Greulich, MD; Joachim Durner, MD; Thomas Müller, MD; Andreas Kupsch, MD; Henning Henningsen, MD; Wolfgang H. Oertel, MD; Gerd Fuchs, MD; Wilfried Kuhn, MD; Petra Niklowitz, MD; Rainer Koch, PhD; Birgit Herting, MD; Heinz Reichmann, MD; for the German Coenzyme Q10 Study Group |date=2007-05-14 |work=Archives of Neurologu }}</ref> Dosage was 300 mg per day.
===Cardiac arrest===
Another recent study shows a survival benefit after cardiac arrest if coenzyme Q<sub>10</sub> is administered in addition to commencing active cooling (to 32–34 degrees Celsius).<ref>
{{cite journal | last = Damian | first = M. S. | coauthors = ''et al.'' | title = Coenzyme Q10 Combined With Mild Hypothermia After Cardiac Arrest | journal = Circulation, American Heart Foundation | volume = 110 | year = 2004 | month = July | pages = 3011–3016 | url = http://www.circ.ahajournals.org/cgi/content/abstract/110/19/3011 | accessdate = 2006-12-01 | pmid = 15520321 | doi = 10.1161/01.CIR.0000146894.45533.C2 }}
</ref>
===Blood pressure===
There are several reports concerning the effect of CoQ<sub>10</sub> on blood pressure in human studies.<ref> Cupp MJ and Tracy TS. Chapter 4: Coenzyme Q10 (Ubiquinone, Ubidecarenone), pp 53-85 in Dietary Supplements edited by Cupp MJ and Tracy TS Humana press, Totowa, New Jersey (2003) </ref>
In a recent meta-analysis of the clinical trials of CoQ<sub>10</sub> 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 Q<sub>10</sub> 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 Q<sub>10</sub> 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.<ref> Rosenfeldt FL, Haas SJ, Krum H, Hadj A, Ng K, Leong J-Y, Watts GF. Coenzyme Q<sub>10</sub> in the treatment of hypertension: a meta-analysis of the clinical trials. J Human Hypertension 21: 297-306, 2007</ref>
===Lifespan===
Studies have shown that low dosages of Coenzyme Q<sub>10</sub> reduce [[oxidation]] and [[DNA]] double-strand breaks, and a combination of a diet rich in [[polyunsaturated fatty acids]] and Coenzyme Q<sub>10</sub> supplementation leads to a longer lifespan in rats<ref name=pmid_15036411>{{cite journal |author=Quiles JL, Ochoa JJ, Huertas JR, Mataix J |title=Coenzyme Q supplementation protects from age-related DNA double-strand breaks and increases lifespan in rats fed on a PUFA-rich diet. |journal=Exp Gerontol. |volume=39 |issue=2 |pages=189–94 |year=2004 |pmid=15036411|doi=10.1016/j.exger.2003.10.002}}</ref>
==Biosynthesis==
The [[1,4-Benzoquinone|benzoquinone]] portion of Coenzyme Q<sub>10</sub> 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 Q<sub>10</sub> shares a common biosynthetic pathway with [[cholesterol]]. The synthesis of an intermediary precursor of Coenzyme Q<sub>10</sub>, [[mevalonate]], is inhibited by some [[beta blocker]]s, blood pressure-lowering medication,<ref>{{cite journal |author=Kishi T, Watanabe T, Folkers K |title=Bioenergetics in clinical medicine XV. Inhibition of coenzyme Q10-enzymes by clinically used adrenergic blockers of beta-receptors |journal=Res Commun Chem Pathol Pharmacol |volume=17 |issue=1 |pages=157–64 |year=1977 |pmid=17892}}</ref> and [[statins]], a class of cholesterol-lowering drugs.<ref>[http://www.cholesterol-and-health.com/Synthesis-Of-Cholesterol.html The Synthesis of Cholesterol<!-- Bot generated title -->]</ref> Statins can reduce serum levels of coenzyme Q<sub>10</sub> by up to 40%.<ref>{{cite journal |author=Ghirlanda G, Oradei A, Manto A, Lippa S, Uccioli L, Caputo S, Greco A, Littarru G |title=Evidence of plasma CoQ10-lowering effect by HMG-CoA reductase inhibitors: a double-blind, placebo-controlled study |journal=J Clin Pharmacol |volume=33 |issue=3 |pages=226–9 |year=1993 |pmid=8463436}}</ref> Some research suggests the logical option of supplementation with coenzyme Q<sub>10</sub> as a routine adjunct to any treatment that may reduce endogenous production of coenzyme Q<sub>10</sub>, based on a balance of likely benefit against very small risk.<ref>{{cite journal |author=Sarter B |title=Coenzyme Q10 and cardiovascular disease: a review |journal=J Cardiovasc Nurs |volume=16 |issue=4 |pages=9–20 |year=2002 |pmid=12597259 |doi=10.1002/cncr.11242<hr><a |doi_brokendate=2008-06-26}}</ref><ref>{{cite journal |author=Thibault A, Samid D, Tompkins A, Figg W, Cooper M, Hohl R, Trepel J, Liang B, Patronas N, Venzon D, Reed E, Myers C |title=Phase I study of lovastatin, an inhibitor of the mevalonate pathway, in patients with cancer |journal=Clin Cancer Res |volume=2 |issue=3 |pages=483–91 |year=1996 |pmid=9816194}}</ref>
==Occurrence in nature==
{{Cleanup-restructure|date=July 2008}}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.<ref>[http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6WJH-4MNHY1G-1&_user=10&_coverDate=08%2F31%2F2007&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=9d3ef3c2d1b8980a4bf544770f19a9e4 Nathalie Soucheta and Serge Laplante, Seasonal variation of Co-enzyme Q10 content in pelagic fish tissues from Eastern Quebec]</ref>
CoQ10 Content of various foods:<ref>[http://www.thefactsaboutfitness.com/research/coq10.htm www.thefactsaboutfitness.com]</ref>
{| class="wikitable sortable"
! Food
! CoQ10 <br>[μg/g]
! Portion of Food <br>[g]
! CoQ10 Amount in Portion <br>[mg]
|- align="center"
| [[Pork]] heart
| 203
| 120
| 24
|- align="center"
| [[Chicken]] leg
| 17
| 120
| 2.0
|- align="center"
| [[Beef]] heart
| 41
| 120
| 4.8
|}
==References==
{{Reflist|2}}
==See also==
*[[Idebenone]] - synthetic analog with reduced oxidant generating properties
==External links==
* [http://www.CoQ10facts.com.au/ A User-Friendly Summary of CoQ<sub>10</sub>]
* [http://faculty.washington.edu/~ely/ An Introduction to Coenzyme Q<sub>10</sub>] at [[University of Washington]]
* [http://lpi.oregonstate.edu/f-w02/coenzymeq10.html Possible Health Benefits of Coenzyme Q<sub>10</sub>] at [[Oregon State University]]
* [http://www.ninds.nih.gov/news_and_events/press_releases/pressrelease_parkinsons_coenzymeq10_101402.htm Study Suggests Coenzyme Q<sub>10</sub> Slows Functional Decline in Parkinson's Disease] at [[National Institute of Neurological Disorders and Stroke]]
{{Electron transport chain}}
{{Enzyme cofactors}}
[[Category:Cellular respiration]]
[[Category:Glycolysis]]
[[Category:Antioxidants]]
[[Category:Dietary antioxidants]]
[[Category:Coenzymes]]
[[Category:Quinones]]
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