Dictionary of terms related with the thematic of the Free Radicals
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Free radical = a molecule with one or more unpaired electrons in its outer orbitals.
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| Acetyl | the monovalent radical CH3CO |
| Acetyl coenzyme A | (acetyl Coa) a thioester of coenzyme A and acetic acid. Acetyl Coa enters the Krebs cycle and is used to acetylate numerous compounds. |
| Acetylcholine | cholinergic agonist and neurotransmitter at the myoneural junction of striated muscle and at the preganglionic sympathetic and parasympathetic synapses. It is the main agonist of nitric oxide. |
| Acetylcysteine | the N-acetyl derivative of L-cysteine (NAC) used as mucolitic agent. NAC enters biologic reactions involving free radicals, through its reduced sulfhydryl group and by increasing glutathione pool. |
| Adriamycin | see under doxorubicin |
| Allopurinol | an isomer of hypoxanthine used in the treatment of gout. It is a powerful inhibitor of xanthine oxidase (see xanthine oxidase), and is widely used as an antioxidant. |
| Alpha lipoic acid | a cofactor of the pyruvate-decarboxilase and other enzymes of the Krebs cycle. It is a mobile component of inner mitochondrial membranes that links the electron transport chain with the complex of ATP synthesis. It also participate in the synthesis of prostaglandins. This low molecular-weight substance is absorbed from the diet and easily diffuses through cell membranes. It participates in redox mechanisms and as an electron donor it is an important antioxidant. It may regenerate other antioxidants such as vitamin E and C. |
| Alpha tocopherol | is the most common type of vitamin E. It is considered the major lipid soluble chain-breaking antioxidant. It mainly protects cell membranes and lipoproteins from free radical oxidation. |
| Amyotrophic lateral sclerosis | neurodegenerative disorder characterized by destruction of motor neurons at the cortex and the spinal cord. It is clinically characterized by progressive paralysis of skeletal muscles. A familiar type of the disease is related to a mutation of superoxide dismutase gen. |
| Angiotensin II | (Ang II) This octapeptide is a potent vasoconstrictor formed from its precursor,angiotensin I by the activity of the angiotensin converting enzym (ACE). Angiotensin I is formed from angiotensinogen by renin. Ang II acts upon specific cell receptors which in turn trigger a signal pathway that releases calcium and produces vasconstriction. Ang II also sitmulates aldosterone and norepinephrine production. It induces free radical formation. |
| Antioxidant | a molecule that at lower concentration than an oxidizable substrate, prevents or delays its oxidation. The antioxidant possesses a chemical structure prone to react with a free radical at a minimal cost for the organism. |
| Apolipoprotein | any of the proteins constituents of lipoproteins. They are classified in A, B, C, and E according to their function. |
| Apoptosis | programmed cell death in response to determined signaling pathways with energy consumption. |
| Arachidonic acid | a polyunsaturated 20 carbon essential fatty acid. The cascade of arachidonic acid produces prostaglandins and thromboxane via the cycloxygenase pathway, and leukotirenes via de lipoxygenase pathway. |
| Arginine | non essential aminoacid produced by hydrolysis of proteins. It constitutes a substrate of nitric oxide synthase for the synthesis of nitric oxide. |
| Ascorbic acid | or vitamin C is a water-soluble antioxidant that can by synthesized by many mammals but not by humans. Besides its antioxidant property, ascorbic acid constitutes the substrate in the synthesis of numerous molecules. |
| Bax | a protein with extensive aminoacid homology with bcl-2. Bax has been shown to form heterodimers with bcl-2 and the ratio of bcl-2/bax determines the survival or death of cells following an apoptotic stimulus |
| Bcl-2 | a family of genes that function as regulators of apoptosis. Bcl-x and bak are the two most known. |
| Beta amyloid protein | a protein constituted by more than 40 aminoacids that is the main compound of senile plaques, the typical histology lesion of Alzheimer disease and Down syndrome. It appears to be a source of reactive oxygen species. |
| Calmodulin | a ubiquitous calcium-binding protein that mediates a variety of cellular responses to calcium. The calcium-calmodulin complex acts as a messenger affecting the activity of numerous enzymes and proteins such as nitric oxide synthase, protein kinases, etc. |
| Cardiolipin | a phospholipid integrating the mitochondrial membrane which interacts with several proteins of the mitochondrial inner membrane preserving their function. It also regulates proton gradients through the membrane. |
| Carnitine | a compound also known as vitamin Bt. This substance is required for mitochondrial beta oxidation of fatty acids, carrying the fatty acids across the mitochondrial membrane to the matrix, where they are transferred back to coenzyme A by enzymatic procedure. |
| Caspase | A family of proteins with protease activity that are responsible of the execution of apoptotic mechanisms. |
| Caspases | Several enzymatic proteins that belong to the family cystein-aspartate-protease. Caspases transmit the apoptotic signal from Fas receptors and induce cellular apoptosis through several mechanisms. |
| Catalase | enzyme that catalizes de conversion of hydrogen peroxide to water and oxygen. |
| Chaperone | protein that assist other molecules to their correct site in the cell. Within this group are the metallochaperones, metal receptor proteins that guide metal ions to proteins and metalloenzymes |
| Chemiluminescence | a method to detect the emission of photons from active molecules at the end stage of a lipid peroxidation reaction. It constitutes an assay to evaluate free radical damage to biomolecules. |
| Coenzyme | an organic non protein molecule, that binds with the protein molecule (apoenzyme) to form the active enzyme. |
| Coenzyme Q | (CoQ10) also known as ubiquinone, is a fat soluble quinone and a cosusbstrate of the electron transport chain in the mitochondria. It is also a powerful lipid soluble antioxidant and can regenerate the oxidized form of vitamin E. |
| Constitutive | Constant or regular expression of a protein or enzyme by the cell. The opposite is inducible. |
| Cystathionine beta synthase | The enzyme that converts homocysteine to cystathionine and then cysteine using vitamin B6 (pyridoxin) as cofactor. |
| Cytochrome c | hemoprotein of the internal mitochondrial membrane that that constitutes a part of the electron transport chain. It accepts electrons from ubiquinol-cytochrome c reductase and transfers them to cytochrome c oxidase. |
| Deferoxamine | a molecule with high iron-binding capacity. It is an iron chelator agent. |
| Dimer | a compound formed by combination of two identical simpler molecules. |
| Diploid | having two sets of chromosomes, as normally found in the somatic cells of higher organisms. |
| Doxorubicin | an anthracycline antibiotic with a wide antitumor spectrum. Treatment with doxorubicin may produce a cardiomyopathy, apparently caused by free radical generation secondary to the metabolism of the drug. |
| Eicosapentanoic acid | (ECA) an omega 3 polyunsaturated 20 carbon fatty acid obtained from fishes. It is a substrate for cyclooxygenase. |
| Eukaryote | an organism whose cells have true nucleus, bounded by a nuclear membrane, within which lie the chromosomes. Eukaryote also contains many membrane bound compartments or organelles. |
| Expression | flow of genetic information from gene to protein. |
| Fenton reaction | A reaction that generates hydroxyl radical (HO.) through the combination of H2O2 with Fe2+ |
| Ferritin | iron bound to the protein apoferritin, one of the main forms of body iron storage. |
| Flavonoids | phytochemicals widely distributed in plants containing a characteristic aromatic trimeric heterocyclic nucleus. Several flavonoids such as catechin, epicatechin, proantocyanidin, and quercetin have antioxidant properties. |
| Free radical | a molecule with one or more unpaired electrons in its outer orbitals. |
| Ginkgo biloba | a tree whose dried leaves have antioxidant properties. |
| Glucose-6-phosphate dehydrogenase | an enzyme of the oxidoreductase class that catalyzes the oxidation of glucose-6-phosphate to a lactone, reducing NADP to NADPH, the main source of electrons. The reaction is the first step in the pentose phosphate pathway of glucose metabolism. |
| Glutathione | a tripeptide composed by glutamic acid, cysteine, and glycine, widely distributed in cells. It participates in various redox reactions, such as the destruction of peroxides and free radicals. When reacting with a free radical it si oxidized to GSSG, and is reconverted back to the reduced GSH form by glutathione reductase. It is the substrate of gutathione peroxidase. |
| Glutahtione peroxidase | enzyme of the oxidoreductase class that catalyzes the detoxifying reduction of hydrogen peroxide and organic peroxides using glutathione as substrate. |
| Guanosine monophosphate | (GMP) a second intracellular messenger. It is synthesized from guansoine triphosphate (GTP ) by guanylate cyclase. GMP increases Ca2+ in cytosol inducing relaxation. It is the final component of NO pathway. |
| Guanylate cyclase | This enzyme is activated by NO to synthetize GMP |
| Haploid | a cell having a single set of chromosomes as the gamete. In humans the haploid number is 23 |
| Homocysteine | a sulphydryl-containing aminoacid derived form the metabolic demethylation of dietary methionine |
| HPLC | high performance liquid chromatography. A high sensible technique to assay a wide variety of molecules and substances in plasma, urine and other physiologic moyens. |
| Hypchlorous acid | (HOCl) A powerful oxidant from leukocytes produced by the enzyme myeloperoxidase |
| Hydrogen Peroxide | (H2O2) a free radical mainly generated by mitochondria or by dismutation of superoxide anion by superoxide dismutase. Through the Fenton reaction H2O2 in the presence of Fe2+ generates hydroxyl radical. H2O2 is catalyzed by catalase producing oxygen and water. |
| Hydroxyl radical | (HO.) a powerful cytotoxic oxidant produced by the Fenton reaction between hydrogen peroxide and Fe2+. |
| Leukotriene | a group of biologically active compounds formed by 20-carbon carboxylic acid chain with several conjugated double bonds. They originate from arachidonic acid cascade via lipoxygenase pathway. Leukotrienes function as regulators of inflammatory and allergic reaction and some of them activate leukocytes. |
| L-NMMA | (NG-monomethyl-L-arginine) An L-arginine analogue that competitively inhibits the synthesis of nitric oxide from L-arginine. In normal subjects, L-NMMA produces vasoconstriction by blunting NO response to acetylcholine. It is commonly used in studies of endothelial function. |
| Lipid peroxidation | radical oxidation of lipids. An autocatalytic process whereby polyunsaturated fatty acids and phospholipids undergo degradation by a chain reaction to form lipid hydroperoxides or lipoperoxides. This process can be followd by measurement of numerous breakdown products, such as hydrocarbons, malondialdehyde, 4-hydroxynonenal, conjugated dienes, singlet oxygen,etc. |
| Lipoperoxide | polyunsaturated fatty acid and phospholipid from cell membranes and lipopoproteins that underwent oxidative degradation by a chain reaction induced by free radicals (se lipid peroxidation) |
| LTB4 | a type of leukotriene that stimulates the rolling of leukocytes on endothelium. |
| Malondialdehide | (MDA) toxic metabolite of lipid peroxidation, which is widely employed as a marker of free radical damage upon lipid molecules. |
| Melatonin | a hormone synthesized by the pineal gland that is involved in circadian cycle regulation. It has antioxidant properties. |
| Metallochaperone | see chaperone |
| Metalloproteinases | zinc dependent endopeptidases, a group of enzymes that hydrolyze peptide bonds within long chains of protein molecules. Although MMPs are crucial to processes such as organ development, wound healing, angiogenesis, and implantation of the fetus, excessive MMP activity has been implicated in disorders such as metastasis, arthritis, and cardiovascular and autoimmune diseases. Malignant tumors are characterized by invasive growth and metastasis. To facilitate this invasive behavior, the enzymatic breakdown of the extracellular matrix (ECM) is a prerequisite. Many human tumors are characterized by locally increased concentrations of matrix metalloproteinases (MMPs), enzymes that are able to degrade this ECM. Two MMPs in particular-gelatinases known as MMP-2 and MMP-9-have been fingered in the process of promoting tumor metastasis and angiogenesis. |
| Microgram | (?g) 0.000015 gm or 10-6 gm |
| Monoamine oxidase | (MAO) enzyme of the oxidoreductase class that catalyzes the oxidative deamination of amines to form aldehydes. Substrates are| serotonin, norepinephrine, epinephrine and dopamine. In this process free radicals are generated. |
| Myeloperoxidase | (MPO) an oxidoreductase that catalyzes the reaction of hydrogen peroxide to produce hypochlorous acid. It is an inducible enzyme of leukocytes. |
| N-acetylcysteine | (NAC) See under acetylcysteine |
| NAD | nicotinamide adenine dinucleotide |
| NADH | the reduced form of nicotinamide adenine dinucleotide. A product of the Krebs, or tricarboxilic acid cycle and a carrier of high energy electrons to the respiratory chain. NADH is regenerated to NAD after losing its electrons. |
| NADP | nicotinamide adenine dinucleotide phosphate. |
| NADPH | the reduced form of NADP. |
| NADPH oxidase | a plasma membrane enzyme that catalyzes the univalent reduction of oxygen using NADPH as electron donor. It constitutes one of the sources of superoxide anion. |
| Nanogram | (ng) one billion grams or 10-9 |
| Nitric oxide | (NO) The most important endothelial vasodilator substance and a strong regulator of the physiologic status of the vessels. |
| Nuclear factor-kappaB | (NF-kB) family of transcription factors involved in the regulation of numerous genes, including acute phase proteins, cell surface receptors, and cytokines. The activation of antioxidant responses is mediated partially through this molecule. |
| Northern blot | a technique similar to Southern blot but performed on fragments of RNA instead of DNA. It does not use restriction enzymes because RNA is a short chain. |
| Peroxynitrite | (ONOO) A toxic product of the reaction between nitric oxide and superoxide anion. |
| Phosphorilation | introduction of a phosphate group (a salt of phosphoric acid or its anions) in a molecule. |
| Polymerase chain reaction | (PCR) this technique amplifies a determined genome sequences, through various steps. Each step reduces nucleotide spectrum. It requires the use of primers to limit the extension of the strand. |
| Propolis | a substance generated by bees composed by flavonoids with strong antioxidant properties. |
| Pyrogallol | poisonous acid used as a topic bactericide. It is employed as oxidant in basic research. |
| Reverse trancriptase | RNA-directed DNA polymerase. |
| Selectin | any of a family of cell adhesion molecules. Their function is to mediate the binding of leukocytes to the vascular endothelium. |
| Singlet oxygen | (1O2 ) oxygen molecule containing high energy electrons. It is produced at the end step of lipid peroxidation reactions and can be detected by chemiluminescence. |
| Southern blot | This technique allows the identification of DNA fragments. The fragments are separated by agarose gel electrophoresis to a nitrocellulose filter, on which specific fragments can be detected by their hybridization to probes. It is used for genetic fingerprints, evolution and ethnic studies. It is also applied for molecular diagnosis of genetic diseases, identification of bacteria, virus and protozoa. This process requires a first step with PCR. |
| Steady-state | regular activity or formation of a molecule in the cell under normal metabolic conditions. |
| Streptozocin | (or Streptozotocin) An antitumor antibiotic of the nitrosourea group, particularly indicated in the islet-cell tumor of the pancreas. It is also used in basic research with the purpose of inducing diabetes by destroying the cells producing insulin. |
| Streptozotocin | (or Streptozocin) An antitumor antibiotic of the nitrosourea group, particularly indicated in the islet-cell tumor of the pancreas. It is also used in basic research with the purpose of inducing diabetes by destroying the cells producing insulin. |
| Superoxide | (O2-) oxygen free radical. It is produced by reduction of molecular oxygen in many biological oxidations (mitochondria, leukocytes, membrane enzymes such as NADPH oxidase and xanthine oxidase). It is scavenged by superoxide dismutase. |
| Superoxide dismutase (SOD) | enzyme of the metal group which catalyzes the superoxide anion reduction to hydrogen peroxide. There are several types, being CuZnSOD (in cytosol) and MnSOD (in mitochondria) the most important ones. |
| TBARS | thiobarbituric acid reactive substances, are an evaluation of dialdehydes produced by free radical damage on cellular components. TBARS constitute a widely used marker of oxidative stress. |
| Telomere | a term applied to each of the extremes of chromosome, which possesses several properties, among them a polarity which prevents their reunion with any fragment after the chromosome has broken. |
| Telomerase | DNA polimerase involved in the formation of telomeres and the maintenance of telomeres sequences during replication. |
| Thiol | any organic compound containing a sulphydril group (SH). |
| Thioredoxin | (TRx) redox regulating molecule which appears to exert antiapoptocic effects. |
| Transcription | the process by which a single-stranded RNA with a base sequence complementary to one strand of a double-stranded DNA is synthesized. |
| Transferrin | the complex of iron and a glycoprotein. Iron is transported in plasma bound to this protein. |
| Translocación | structural aberration of a chromosome where a segment is transferred to a non homologous chromosome. |
| Tumor necrosis factor-alpha | (TNF-alpha) Proteine of the cytokine family expressed by monocytes in response to inflammatory stimuli. It binds to specific cell receptors which in turn trigger signal of cell proliferation or apoptosis. The excessive production of TNF-alpha may generate endotoxic shock. This protein shares the same receptors with leukotriene-alpha (LT-alpha), which is produced by T-lymphocytes. |
| Vitamin C | see ascorbic acid. |
| Vitamin E | is a generic term for all tocopherols and their derivatives having the biological activity of RRR-alpha-tocopherol. |
| Western blot | a technique for analyzing and identifying protein antigens: the proteins are separated by electrophoresis in polyacrylamide gel, then transferred (blotted) onto a nitrocellulose membrane, where they bind in the same pattern as they formed in the gel. |
| Xanthine oxidase |
(XO) an enzyme of the
oxidoreductase class that catalyzes the
oxidation of hypoxanthine to xanthine
and of xanthine to uric acid plus two
molecules of superoxide anion. In this
form XO becomes an important source of
this free radical. The enzyme which is
mainly produced by endothelial cells is
in the form of xanthine dehydorgenase (XDH).
Xanthine dehydorgenase is converted to
XO by increased cytosolic calcium and
proteolisis, conditions observed in
tissue ischemia. [Karl Note: This "long-lost" term was one that I popularized several decades ago. This is the substance found in the fat of cow milk. When you drink homogenized milk, this type of fat can pass through the intestinal wall easily. It attacks the inner lining of the artery and for many years I thought of it as one of the primary causes of heart disease. I would attack and dissolve the inner lining of the artery, the body would try to heal that area by covering it with a patch of cholesterol and calcium, causing blockage and heart disease.] |
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Dictionary of terms related with the thematic of the Free Radicals. |
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| Acetyl | the monovalent radical CH3CO |
| Acetyl coenzyme A | (acetyl Coa) a thioester of coenzyme A and acetic acid. Acetyl Coa enters the Krebs cycle and is used to acetylate numerous compounds. |
| Acetylcholine | cholinergic agonist and neurotransmitter at the myoneural junction of striated muscle and at the preganglionic sympathetic and parasympathetic synapses. It is the main agonist of nitric oxide. |
| Acetylcysteine | the N-acetyl derivative of L-cysteine (NAC) used as mucolitic agent. NAC enters biologic reactions involving free radicals, through its reduced sulfhydryl group and by increasing glutathione pool. |
| Adriamycin | see under doxorubicin |
| Allopurinol | an isomer of hypoxanthine used in the treatment of gout. It is a powerful inhibitor of xanthine oxidase (see xanthine oxidase), and is widely used as an antioxidant. |
| Alpha lipoic acid | a cofactor of the pyruvate-decarboxilase and other enzymes of the Krebs cycle. It is a mobile component of inner mitochondrial membranes that links the electron transport chain with the complex of ATP synthesis. It also participate in the synthesis of prostaglandins. This low molecular-weight substance is absorbed from the diet and easily diffuses through cell membranes. It participates in redox mechanisms and as an electron donor it is an important antioxidant. It may regenerate other antioxidants such as vitamin E and C. |
| Alpha tocopherol | is the most common type of vitamin E. It is considered the major lipid soluble chain-breaking antioxidant. It mainly protects cell membranes and lipoproteins from free radical oxidation. |
| Amyotrophic lateral sclerosis | neurodegenerative disorder characterized by destruction of motor neurons at the cortex and the spinal cord. It is clinically characterized by progressive paralysis of skeletal muscles. A familiar type of the disease is related to a mutation of superoxide dismutase gen. |
| Angiotensin II | (Ang II) This octapeptide is a potent vasoconstrictor formed from its precursor,angiotensin I by the activity of the angiotensin converting enzym (ACE). Angiotensin I is formed from angiotensinogen by renin. Ang II acts upon specific cell receptors which in turn trigger a signal pathway that releases calcium and produces vasconstriction. Ang II also sitmulates aldosterone and norepinephrine production. It induces free radical formation. |
| Antioxidant | a molecule that at lower concentration than an oxidizable substrate, prevents or delays its oxidation. The antioxidant possesses a chemical structure prone to react with a free radical at a minimal cost for the organism. |
| Apolipoprotein | any of the proteins constituents of lipoproteins. They are classified in A, B, C, and E according to their function. |
| Apoptosis | programmed cell death in response to determined signaling pathways with energy consumption. |
| Arachidonic acid | a polyunsaturated 20 carbon essential fatty acid. The cascade of arachidonic acid produces prostaglandins and thromboxane via the cycloxygenase pathway, and leukotirenes via de lipoxygenase pathway. |
| Arginine | non essential aminoacid produced by hydrolysis of proteins. It constitutes a substrate of nitric oxide synthase for the synthesis of nitric oxide. |
| Ascorbic acid | or vitamin C is a water-soluble antioxidant that can by synthesized by many mammals but not by humans. Besides its antioxidant property, ascorbic acid constitutes the substrate in the synthesis of numerous molecules. |
| Bax | a protein with extensive aminoacid homology with bcl-2. Bax has been shown to form heterodimers with bcl-2 and the ratio of bcl-2/bax determines the survival or death of cells following an apoptotic stimulus |
| Bcl-2 | a family of genes that function as regulators of apoptosis. Bcl-x and bak are the two most known. |
| Beta amyloid protein | a protein constituted by more than 40 aminoacids that is the main compound of senile plaques, the typical histology lesion of Alzheimer disease and Down syndrome. It appears to be a source of reactive oxygen species. |
| Calmodulin | a ubiquitous calcium-binding protein that mediates a variety of cellular responses to calcium. The calcium-calmodulin complex acts as a messenger affecting the activity of numerous enzymes and proteins such as nitric oxide synthase, protein kinases, etc. |
| Cardiolipin | a phospholipid integrating the mitochondrial membrane which interacts with several proteins of the mitochondrial inner membrane preserving their function. It also regulates proton gradients through the membrane. |
| Carnitine | a compound also known as vitamin Bt. This substance is required for mitochondrial beta oxidation of fatty acids, carrying the fatty acids across the mitochondrial membrane to the matrix, where they are transferred back to coenzyme A by enzymatic procedure. |
| Caspase | A family of proteins with protease activity that are responsible of the execution of apoptotic mechanisms. |
| Caspases | Several enzymatic proteins that belong to the family cystein-aspartate-protease. Caspases transmit the apoptotic signal from Fas receptors and induce cellular apoptosis through several mechanisms. |
| Catalase | enzyme that catalizes de conversion of hydrogen peroxide to water and oxygen. |
| Chaperone | protein that assist other molecules to their correct site in the cell. Within this group are the metallochaperones, metal receptor proteins that guide metal ions to proteins and metalloenzymes |
| Chemiluminescence | a method to detect the emission of photons from active molecules at the end stage of a lipid peroxidation reaction. It constitutes an assay to evaluate free radical damage to biomolecules. |
| Coenzyme | an organic non protein molecule, that binds with the protein molecule (apoenzyme) to form the active enzyme. |
| Coenzyme Q | (CoQ10) also known as ubiquinone, is a fat soluble quinone and a cosusbstrate of the electron transport chain in the mitochondria. It is also a powerful lipid soluble antioxidant and can regenerate the oxidized form of vitamin E. |
| Constitutive | Constant or regular expression of a protein or enzyme by the cell. The opposite is inducible. |
| Cystathionine beta synthase | The enzyme that converts homocysteine to cystathionine and then cysteine using vitamin B6 (pyridoxin) as cofactor. |
| Cytochrome c | hemoprotein of the internal mitochondrial membrane that that constitutes a part of the electron transport chain. It accepts electrons from ubiquinol-cytochrome c reductase and transfers them to cytochrome c oxidase. |
| Deferoxamine | a molecule with high iron-binding capacity. It is an iron chelator agent. |
| Dimer | a compound formed by combination of two identical simpler molecules. |
| Diploid | having two sets of chromosomes, as normally found in the somatic cells of higher organisms. |
| Doxorubicin | an anthracycline antibiotic with a wide antitumor spectrum. Treatment with doxorubicin may produce a cardiomyopathy, apparently caused by free radical generation secondary to the metabolism of the drug. |
| Eicosapentanoic acid | (ECA) an omega 3 polyunsaturated 20 carbon fatty acid obtained from fishes. It is a substrate for cyclooxygenase. |
| Eukaryote | an organism whose cells have true nucleus, bounded by a nuclear membrane, within which lie the chromosomes. Eukaryote also contains many membrane bound compartments or organelles. |
| Expression | flow of genetic information from gene to protein. |
| Fenton reaction | A reaction that generates hydroxyl radical (HO.) through the combination of H2O2 with Fe2+ |
| Ferritin | iron bound to the protein apoferritin, one of the main forms of body iron storage. |
| Flavonoids | phytochemicals widely distributed in plants containing a characteristic aromatic trimeric heterocyclic nucleus. Several flavonoids such as catechin, epicatechin, proantocyanidin, and quercetin have antioxidant properties. |
| Free radical | a molecule with one or more unpaired electrons in its outer orbitals. |
| Ginkgo biloba | a tree whose dried leaves have antioxidant properties. |
| Glucose-6-phosphate dehydrogenase | an enzyme of the oxidoreductase class that catalyzes the oxidation of glucose-6-phosphate to a lactone, reducing NADP to NADPH, the main source of electrons. The reaction is the first step in the pentose phosphate pathway of glucose metabolism. |
| Glutathione | a tripeptide composed by glutamic acid, cysteine, and glycine, widely distributed in cells. It participates in various redox reactions, such as the destruction of peroxides and free radicals. When reacting with a free radical it si oxidized to GSSG, and is reconverted back to the reduced GSH form by glutathione reductase. It is the substrate of gutathione peroxidase. |
| Glutahtione peroxidase | enzyme of the oxidoreductase class that catalyzes the detoxifying reduction of hydrogen peroxide and organic peroxides using glutathione as substrate. |
| Guanosine monophosphate | (GMP) a second intracellular messenger. It is synthesized from guansoine triphosphate (GTP ) by guanylate cyclase. GMP increases Ca2+ in cytosol inducing relaxation. It is the final component of NO pathway. |
| Guanylate cyclase | This enzyme is activated by NO to synthetize GMP |
| Haploid | a cell having a single set of chromosomes as the gamete. In humans the haploid number is 23 |
| Homocysteine | a sulphydryl-containing aminoacid derived form the metabolic demethylation of dietary methionine |
| HPLC | high performance liquid chromatography. A high sensible technique to assay a wide variety of molecules and substances in plasma, urine and other physiologic moyens. |
| Hypchlorous acid | (HOCl) A powerful oxidant from leukocytes produced by the enzyme myeloperoxidase |
| Hydrogen Peroxide | (H2O2) a free radical mainly generated by mitochondria or by dismutation of superoxide anion by superoxide dismutase. Through the Fenton reaction H2O2 in the presence of Fe2+ generates hydroxyl radical. H2O2 is catalyzed by catalase producing oxygen and water. |
| Hydroxyl radical | (HO.) a powerful cytotoxic oxidant produced by the Fenton reaction between hydrogen peroxide and Fe2+. |
| Leukotriene | a group of biologically active compounds formed by 20-carbon carboxylic acid chain with several conjugated double bonds. They originate from arachidonic acid cascade via lipoxygenase pathway. Leukotrienes function as regulators of inflammatory and allergic reaction and some of them activate leukocytes. |
| L-NMMA | (NG-monomethyl-L-arginine) An L-arginine analogue that competitively inhibits the synthesis of nitric oxide from L-arginine. In normal subjects, L-NMMA produces vasoconstriction by blunting NO response to acetylcholine. It is commonly used in studies of endothelial function. |
| Lipid peroxidation | radical oxidation of lipids. An autocatalytic process whereby polyunsaturated fatty acids and phospholipids undergo degradation by a chain reaction to form lipid hydroperoxides or lipoperoxides. This process can be followd by measurement of numerous breakdown products, such as hydrocarbons, malondialdehyde, 4-hydroxynonenal, conjugated dienes, singlet oxygen,etc. |
| Lipoperoxide | polyunsaturated fatty acid and phospholipid from cell membranes and lipopoproteins that underwent oxidative degradation by a chain reaction induced by free radicals (se lipid peroxidation) |
| LTB4 | a type of leukotriene that stimulates the rolling of leukocytes on endothelium. |
| Malondialdehide | (MDA) toxic metabolite of lipid peroxidation, which is widely employed as a marker of free radical damage upon lipid molecules. |
| Melatonin | a hormone synthesized by the pineal gland that is involved in circadian cycle regulation. It has antioxidant properties. |
| Metallochaperone | see chaperone |
| Metalloproteinases | zinc dependent endopeptidases, a group of enzymes that hydrolyze peptide bonds within long chains of protein molecules. Although MMPs are crucial to processes such as organ development, wound healing, angiogenesis, and implantation of the fetus, excessive MMP activity has been implicated in disorders such as metastasis, arthritis, and cardiovascular and autoimmune diseases. Malignant tumors are characterized by invasive growth and metastasis. To facilitate this invasive behavior, the enzymatic breakdown of the extracellular matrix (ECM) is a prerequisite. Many human tumors are characterized by locally increased concentrations of matrix metalloproteinases (MMPs), enzymes that are able to degrade this ECM. Two MMPs in particular-gelatinases known as MMP-2 and MMP-9-have been fingered in the process of promoting tumor metastasis and angiogenesis. |
| Microgram | (?g) 0.000015 gm or 10-6 gm |
| Monoamine oxidase | (MAO) enzyme of the oxidoreductase class that catalyzes the oxidative deamination of amines to form aldehydes. Substrates are| serotonin, norepinephrine, epinephrine and dopamine. In this process free radicals are generated. |
| Myeloperoxidase | (MPO) an oxidoreductase that catalyzes the reaction of hydrogen peroxide to produce hypochlorous acid. It is an inducible enzyme of leukocytes. |
| N-acetylcysteine | (NAC) See under acetylcysteine |
| NAD | nicotinamide adenine dinucleotide |
| NADH | the reduced form of nicotinamide adenine dinucleotide. A product of the Krebs, or tricarboxilic acid cycle and a carrier of high energy electrons to the respiratory chain. NADH is regenerated to NAD after losing its electrons. |
| NADP | nicotinamide adenine dinucleotide phosphate. |
| NADPH | the reduced form of NADP. |
| NADPH oxidase | a plasma membrane enzyme that catalyzes the univalent reduction of oxygen using NADPH as electron donor. It constitutes one of the sources of superoxide anion. |
| Nanogram | (ng) one billion grams or 10-9 |
| Nitric oxide | (NO) The most important endothelial vasodilator substance and a strong regulator of the physiologic status of the vessels. |
| Nuclear factor-kappaB | (NF-kB) family of transcription factors involved in the regulation of numerous genes, including acute phase proteins, cell surface receptors, and cytokines. The activation of antioxidant responses is mediated partially through this molecule. |
| Northern blot | a technique similar to Southern blot but performed on fragments of RNA instead of DNA. It does not use restriction enzymes because RNA is a short chain. |
| Peroxynitrite | (ONOO) A toxic product of the reaction between nitric oxide and superoxide anion. |