Coenzyme Q10 Review Article
CoEnzyme Q10 is a substance boosting production of cellular energy and providing additional support for the cardiovascular system. The drug is increasingly popular for the maintenance of physical activeness during intensive training as well as for general use. In some experiments coenzyme Q10 has shown the ability to prolong life and to prevent as well as treat many diseases, including Heart Disease, Congestive Heart Failure (CHF), High Blood Pressure, High Cholesterol, Diabetes, Heart Damage caused by Chemotherapy, Breast Cancer, Periodontal (gum) Disease. CoEnzyme Q10 is necessary for all healthy individuals after 30 years for stimulation and maintenance of the organism, increase of energy and vitality, prevention of premature aging and depression of the immune system.
* Each capsule contains: 50 mg CoQ10, 10 mg Quercetine, 50 mkg Selenium, 10 mg vit E, 60 mg vit C, 2 mg Beta-carotene.
See also: General premature aging.
||Add to basket
|50 mg Q10, 15 mg Resveratrol, 200 mcg Folic acid
|50 mg CoQ10, 10 mg Quercetine, 10 mg Vit. E
|60 mg CoQ10
|100 mg CoQ10
Whenever a molecule in the cell requires energy in order to initiate a molecular process, enzymes first remove a phosphate group from ATP and then attach it to the molecule. The attachment of ATP to molecules causes them to undergo the change that is required for them to perform their tasks. The execution of those tasks causes them to lose their phosphate group again. Thus, their energy source gets used up, and the cell must continuously regenerate ATP from ADP and phosphate groups in order to replenish its energy stores. The process by which the generation of ATP occurs in the cell is called cellular respiration. In heterotrophic organisms like humans, the fuel that drives the generation of ATP is the food that we eat - mainly fats, carbohydrates and proteins.
Fats, carbohydrates, and proteins usually come in the form of polymers - i.e. large molecules that are made up of smaller molecular units called monomers. Some of our food, like glucose, comes in the form of monomers. In our digestive tract, polymers are broken down into monomers. Monomers are able to go through a series of processes designed to produce ATP for the cells. We will not go into detail about the first couple of processes in the series. Let’s only mention that they involve the removal of electrons from the hydrogen atoms of food monomers, and the addition of these electrons to a co-enzyme called NAD+ (Nicotinamide Adenine Dinucleotide), and sometimes to a cofactor called FAD (flavin adenine dinucleotide). This last process is performed by special enzymes called dehydrogenases. Remember that each hydrogen atom holds one electron. In the case where NAD+ is involved, dehydrogenases remove two complete hydrogen atoms from foods but then they only deliver two electrons and one proton from these hydrogen atoms to NAD+. Through this process, NAD+ becomes NADH. As we can notice, by turning into NADH, NAD+ loses its positive charge. And this happens because there are two electrons (which are negatively charged) and only one proton (which is positively charged) being delivered to it - so the net charge that it gains is a negative one. In the case where FAD is involved, two hydrogen atoms are transferred to it, turning it into FADH2.
What’s important about NADH and FADH2 is that they can give off their electrons to the next process of cellular respiration, namely the electron transport chain (ETC). The ETC is located in the inner membrane of mitochondria. It is a succession of molecules where each molecule in the series is more electronegative than its preceding one (electronegativity is the affinity by which an atom or a molecule attracts electrons). At the end of the ETC is the very electronegative oxygen molecule. Thus, electrons given off from NADH or FADH2 to the ETC pass on from molecule to molecule until they reach oxygen. At this point electrons join oxygen molecules and simultaneously hydrogen ions join as well, leading to the formation of water molecules (H2O).
ETC consists of molecules that are mostly proteins. They group together to form four protein complexes that are named in accordance to their position in the ETC: complex I to complex IV.
The passing on of electrons from one complex to the next, causes complexes I, III and IV to pump H+ ions across the mitochondrial membrane, from the mitochondrial matrix into the intermembrane space (figure 1). This causes the creation of a H+ concentration gradient: the intermembrane space ends up having far higher concentrations of H+ than the matrix. Naturally, H+ ions are inclined to move down their concentration gradient from the intermembrane space back into the matrix. But the only channel through which they can move back across the membrane, is a protein complex called ATP synthase.
One of the molecular subunits of which ATP synthase consists is a rotor. The flow of H+ ions through the enzyme causes its rotor to spin, which in turn causes conformational changes to the shape of the enzyme that activate catalytic sites where ADP and inorganic phosphates can combine to form ATP.
Figure 1: The electron transport chain as described in the text. I, II, III, and IV indicate protein complexes I - IV respectively. Cyt C, which stands for cytochrome C, is another electron carrier like coenzyme Q (not discussed in the text). The red arrows indicate the flow of electrons; the green arrows indicate the flow of protons (hydrogen ions).
Coenzyme Q (CQ) is part of the ETC, and the only member that is not a protein - it is a lipid. It is located near protein complexes I, II and III. It functions as an electron carrier, receiving electrons from NADH and FADH2 via complexes I and II respectively, and delivering them to complex III. Thus, CQ is essential for cellular respiration to take place, and CQ deficiency can lead to serious disorders.
Coenzyme Q as a free radical scavenger
As mentioned above, CQ goes through both the process of grabbing electrons from complexes I and II, and that of giving the electrons away to complex III. When a substance gains electrons, we say that it gets reduced. When a substance loses electrons, we say that it gets oxidized. Consequently, CQ can change between reduced and oxidized states – in its reduced state it takes the form of quinol while in its oxidized state, it takes the form of quinone.
Why is this important? You have probably heard of free radicals: they are substances with one or more unpaired electrons which makes them unstable, and causes them to seek out electrons from other chemical structures in order to “steal” them and thus complete their own electron pairs. In organisms, free radicals can thus react with healthy biomolecules in this way and disrupt their normal function. In addition, when these healthy biomolecules lose their electrons to free radicals, they transform into free radicals themselves. This means that a single free radical can initiate a series of events with disastrous proportions.
The mitochondria are the source of most free radicals found in our body. This is because mitochondria house the ETC. As described above, the ETC is a place where a lot of single electrons move around, while the mitochondrion is also known to be a place where many oxygen atoms are found, too. Sometimes it happens that electrons leak from the ETC, specifically at complexes I and III, and react with O2 molecules to form superoxide (O2.-), a free radical that belongs to the reactive oxygen species (ROS).
Superoxide can then be converted into hydrogen peroxide (H2O2, another ROS) by an enzyme called superoxide dismutase (SOD). This can take place either in the mitochondrial matrix or in the cytosol.
Quinol, which, being a reduced form of CQ, has extra electrons, can scavenge ROS substances by giving them the electrons they need (i.e. it reduces them) and thus neutralising them. Because this causes ROS to lose their oxidizing potential, CQ is said to act as an antioxidant (there are also other substances that act as antioxidants in the body. The most known ones are vitamins C and E). Insufficient amounts of CQ can result from ageing, cancer, ingestion of drugs that inhibit its biosynthesis (like statins) or genetic mutations where the affected genes are involved in CQ’s biosynthesis (Crane, 2001). CQ deficiency could lead to more production of ROS than cells’ antioxidants can scavenge, which leads to damages in cells, a phenomenon known as oxidative stress (Mancuso et al., 2010).
During oxidative stress, ROS can damage biomolecules like lipids, proteins and nucleic acids (RNA and DNA). Oxidative damage in nuclear DNA and in mitochondrial DNA can be deleterious in cells where DNA does not get replaced through a cellular division mechanism (e.g. neuronal cells). Mitochondrial DNA is especially prone to oxidative damage for the following reasons:
- it is located near the inner mitochondrial membrane, where ROS are formed,
- unlike nuclear DNA it is not protected by histones
- its repairing mechanisms are not as efficient as those of nuclear DNA (Mancuso et al., 2010).
Damage to mitochondrial DNA can be disastrous because many of its genes encode proteins of the ETC, and a defective ETC can lead to increased production of ROS and subsequently cellular deaths that can lead to further damages to the organism (Mancuso et al., 2010).
Figure 2: O2.- is produced in the mitochondrion and because its electron pairs are incomplete it will seek electrons from healthy biomolecules in order to complete its own electron pairs. The biomolecules from which it "steals" electrons become themselves free radicals and lose their normal functions – a phenomenon called oxidative stress. Perhaps more deleteriously, free radicals can also damage mitochondrial DNA (mDNA) in the same way. O2.- can also be converted to H2O2 (another ROS) by SOD. An antioxidant like CoQ10 holds extra electrons and it can transfer some to the ROS turning them into unreactive molecules.
COENZYME Q10 AND ITS BENEFICIAL EFFECTS
The “Q” in “coenzyme Q” refers to the quinone group found in its chemical structure. The structure also contains a tail of isoprenyl monomers. Depending on the organism’s species, the number of isoprenyl monomers can be 6 or 10. In humans, coenzyme Q has 10 monomers, and so it is called Coenzyme Q10 (CoQ10).
Figure 3: CoQ10's chemical structure
Rarely do so many scientists agree on the same thing as anti-ageing scientists agree about the benefits of administration of coenzyme Q10. CoQ10 has many therapeutic effects, which coupled with its lack of side effects, makes it a valuable tool against the problems commonly associated ageing. Other than an overall feeling of wellness and a boost in energy, CoQ10 has showed beneficial effects in many conditions, including age-related ones:
Parkinson’s Disease (PD)
CoQ10 deficits were found in PD patients (Mancuso et al., 2010). In a few studies on PD patients, treating with CoQ10 was shown to improve the symptoms of PD (Bonakdar, 2005; M?ller et al., 2003). Patients with progressive supranuclear palsy (PSP) also showed a reduction of symptoms after CoQ10 administration (Mancuso et al., 2010).
Studies have shown that CoQ10 administration can reduce the frequency of migraine attacks (Bonakdar, 2005).
CoQ10 was shown to reduce the symptoms of Mitochondrial Encephalomyopathies (Bonakdar, 2005).
Studies showed a mean decrease in systolic and diastolic blood pressure (Bonakdar, 2005; Burke et al., 2001).
The administration of CoQ10 in subjects of myocardial infarction lead to a reduction of myocardial infarctions, cardiac deaths, and other cardiac events (Bonakdar, 2005).
CoQ 10 was shown to fight skin ageing by reducing oxidation, and subsequently the formation of wrinkles (Hoppe et al., 1999).
The administration of CoQ10 was shown to improve glycemic control in diabetic patients by fighting oxidative stress (Bonakdar, 2005).
DNA damages that can be caused by ROS are thought to contribute to carcinogenesis (Portakal et al., 2000). CoQ10 can probably be beneficial to cancer patients, though this is still an open question.
Other conditions that it may possibly benefit
Friedreich’s ataxia and Amyotrophic Lateral Sclerosis (Mancuso et al., 2010), Huntington’s Disease, Chronic Heart Failure (Bonakdar, 2005), Duchenne’s Muscular Dystrophy, Human Immunodeficiency Virus and Acquired Immunodeficiency Syndrome, Periodontal disease, and Alzheimer’s disease (Bonakdar, 2005).
MECHANISMS OF ACTION
As previously mentioned, CoQ10 owes its therapeutic effects mainly to acting as an electron carrier in the ETC and to scavenging free radicals. Another important role of CoQ10 is that it can “rescue” tocopheryl from being oxidized by radicals (Crane, 2001). Tocopheryl is also known as vitamin E, which is another valuable antioxidant.
SIDE EFFECTS/ADVERSE REACTIONS
There are no known negative side effects associated with CoQ10 (Mancuso et al., 2010, Bonakdar, 2005).
Bonakdar RA, Guarneri E, 2005, Coenzyme Q10, Am Fam Physician; 72(6):1065-70.
Burke BE, Neuenschwander R, Olson RD, 2001, Randomized, double-blind, placebo-controlled trial of coenzyme Q10 in isolated systolic hypertension, South Med J; 94(11):1112-7.
Crane FL, 2001, Biochemical functions of coenzyme Q10, J Am Coll Nutr; 20(6):591-8.
Hoppe U, Bergemann J, Diembeck W, Ennen J, Gohla S, Harris I, Jacob J, Kielholz J, Mei W, Pollet D, Schachtschabel D, Sauermann G, Schreiner V, St?b F, Steckel F, 1999, Coenzyme Q10, a cutaneous antioxidant and energizer Biofactors; 9(2-4):371-8.
Lambert AJ, Brand MD, 2004, Inhibitors of the quinone-binding site allow rapid superoxide production from mitochondrial NADH:ubiquinone oxidoreductase (complex I), J Biol Chem; 279(38):39414-20.
Mancuso M, Orsucci D, Volpi L, Calsolaro V, Siciliano G, 2010, Coenzyme Q10 in neuromuscular and neurodegenerative disorders, Curr Drug Targets; 11(1):111-21.
M?ller T, B?ttner T, Gholipour AF, Kuhn W, 2003, Coenzyme Q10 supplementation provides mild symptomatic benefit in patients with Parkinson's disease, Neurosci Lett; 341(3):201-4.
Portakal O, Ozkaya O, Erden Inal M, Bozan B, Koşan M, Sayek I, 2000, Coenzyme Q10 concentrations and antioxidant status in tissues of breast cancer patients, Clin Biochem; 33(4):279-84.
Singh RB, Wander GS, Rastogi A, Shukla PK, Mittal A, Sharma JP, Mehrotra SK, Kapoor R, Chopra RK, 1998, Randomized, double-blind placebo-controlled trial of coenzyme Q10 in patients with acute myocardial infarction, Cardiovasc Drugs Ther; 12(4):347-53.
Antioxidants and Vitamines
Coenzyme Q10 Review Article