WorldWideScience

Sample records for radical-mediated oxidative damage

  1. Biochemistry and pathology of radical-mediated protein oxidation

    DEFF Research Database (Denmark)

    Dean, R T; Fu, S; Stocker, R

    1997-01-01

    Radical-mediated damage to proteins may be initiated by electron leakage, metal-ion-dependent reactions and autoxidation of lipids and sugars. The consequent protein oxidation is O2-dependent, and involves several propagating radicals, notably alkoxyl radicals. Its products include several catego...

  2. Dityrosine, 3,4-Dihydroxyphenylalanine (DOPA), and radical formation from tyrosine residues on milk proteins with globular and flexible structures as a result of riboflavin-mediated photo-oxidation

    DEFF Research Database (Denmark)

    Dalsgaard, Trine Kastrup; Nielsen, Jacob Holm; Brown, Bronwyn

    2011-01-01

    Riboflavin-mediated photo-oxidative damage to protein Tyr residues has been examined to determine whether protein structure influences competing protein oxidation pathways in single proteins and protein mixtures. EPR studies resulted in the detection of Tyr-derived o-semiquione radicals, with thi......Riboflavin-mediated photo-oxidative damage to protein Tyr residues has been examined to determine whether protein structure influences competing protein oxidation pathways in single proteins and protein mixtures. EPR studies resulted in the detection of Tyr-derived o-semiquione radicals...

  3. Renal deterioration caused by carcinogens as a consequence of free radical mediated tissue damage: a review of the protective action of melatonin

    Energy Technology Data Exchange (ETDEWEB)

    Gultekin, Fatih; Hicyilmaz, Hicran [Suleyman Demirel University, School of Medicine, Department of Biochemistry, Isparta (Turkey)

    2007-10-15

    This brief review summarizes some of the publications that document the preventive role of melatonin in kidney damage caused by carcinogens such as 2-nitropropane, arsenic, carbon tetrachloride, nitrilotriacetic acid and potassium bromate. Numerous chemicals generate excessive free radicals that eventually induce renal worsening. Melatonin partially or totally prevents free radical mediated tissue damages induced by many carcinogens. Protective actions of melatonin against the harmful effects of carcinogens are believed to stem from its direct free radical scavenging and indirect antioxidant activities. Dietary or pharmacologically given melatonin may attenuate the oxidative stress, thereby mitigating the subsequent renal damage. (orig.)

  4. Genomics and radical mediated DNA damage: major differences between ionizing radiation and DNA-cleaving enediynes

    International Nuclear Information System (INIS)

    Cosgrove, J.P.; Begley, T.J.; Samson, L.D.; Dedon, P.C.

    2003-01-01

    While the evidence is strong for radical-mediated oxidative processes in the pathophysiology of cancer and aging, the mechanisms by which cells respond to oxidative stress have eluded definition. To this end, we have undertaken genomic studies comparing the response of S. cerevisiae to DNA-specific oxidizing agents, the enediynes calicheamicin (CAL), esperamicin (ESP), and neocarzinostatin (NCS), and the non-specific gamma-radiation (RAD). While RAD results in relatively indiscriminate oxidation of cellular molecules, the enediynes are highly specific to DNA and produce damage by a common mechanism involving radical-mediated oxidation of deoxyribose. Transcriptional profiling in response to these agents (80% survival; 15 min exposure; Affymetrix) revealed unexpected differences between RAD and the enediynes and among the three enediynes. Only 2 genes responded in common to all agents, while 9 genes were regulated in common for the 3 enediynes (no DNA repair genes altered in common). The limited common gene expression changes for the 3 enediynes may result from differences in deoxyribose oxidation chemistry, DNA and chromatin targets or the proportions of single- and double-strand DNA lesions. RAD produced a more robust response than the enediynes, altering expression of 195 and 52 genes by more than 2- and 5-fold, respectively, compared to 16-44 and *2 genes, respectively, for the enediynes. This suggests that the transcriptional response varies in intensity according to the number of cellular features affected by the toxin. Genes showing the strongest up-regulation with RAD: ribonucleotide reductase, multidrug resistance, DS break repair/RAD51, GSH transferase; strongly reduced gene expression: TEL1 (damage signaling), NAT2 (acetyltransferase). Genomic phenotyping studies, using a subset of the Research Genetics deletion library, revealed that loss of apn1, the major AP endonuclease, caused resistance to NCS, possibly due to reduced formation of protein-DNA cross

  5. Radical-Mediated Enzymatic Polymerizations

    Science.gov (United States)

    Zavada, Scott R.; Battsengel, Tsatsral; Scott, Timothy F.

    2016-01-01

    Polymerization reactions are commonly effected by exposing monomer formulations to some initiation stimulus such as elevated temperature, light, or a chemical reactant. Increasingly, these polymerization reactions are mediated by enzymes―catalytic proteins―owing to their reaction efficiency under mild conditions as well as their environmental friendliness. The utilization of enzymes, particularly oxidases and peroxidases, for generating radicals via reduction-oxidation mechanisms is especially common for initiating radical-mediated polymerization reactions, including vinyl chain-growth polymerization, atom transfer radical polymerization, thiol–ene step-growth polymerization, and polymerization via oxidative coupling. While enzyme-mediated polymerization is useful for the production of materials intended for subsequent use, it is especially well-suited for in situ polymerizations, where the polymer is formed in the place where it will be utilized. Such polymerizations are especially useful for biomedical adhesives and for sensing applications. PMID:26848652

  6. Protection of naturally occurring antioxidants against oxidative damages to protein

    International Nuclear Information System (INIS)

    Zhu Hongping; Zhang Zhaoxia; Hao Shumei; Wang Wenfeng; Yao Side

    2006-01-01

    One of the most compelling theories explaining age-related deterioration is the free radical theory of aging. It has been shown that reactive oxygen species are involved in oxidative damages to biomolecules and this is related to a number of diseases. Proteins, the second most abundant components of cells (next to water by weight), are now increasingly recognized as major biological targets of oxidative damages. Convincing evidences have indicated that damages to protein have been implicated in Alzheimer's disease, Parkinson's disease, cancer, and aging. Antioxidant has been the subject of great attention because they are known to lower the risk of cardiovascular and other diseases. Hydroxycinnamic acid derivatives (HCAs) are antioxidants abundant in tea, red wine, fruits, beverages and various medicinal plants. Results showed that they exhibit remarkable activity for scavenging oxidizing radicals and triplet states. The protective effects of four kinds of HCAs on oxidative damages to lysozyme were investigated in our lab. Protein damages induced by two different paradigms: riboflavin-sensitized photooxidation and hydroxyl ( . OH)-mediated oxidation, were investigated using polyacrylamide gel electrophoresis. HCAs were found to inhibit the cross-linking of protein induced by riboflavin-mediated photooxidation. HCAs also exhibited protection effect on lysozyme damage induced by γ-ray irradiation. The rate constants for quenching triplet state of riboflavin by lysozyme and HCAs were obtained using laser flash photolysis. The protective mechanism was proposed based on the dynamic study. HCAs were found to protect protein against oxidation by scavenging oxidizing species and repairing the damaged protein. (authors)

  7. Oxidative damage of U937 human leukemic cells caused by hydroxyl radical results in singlet oxygen formation.

    Directory of Open Access Journals (Sweden)

    Marek Rác

    Full Text Available The exposure of human cells to oxidative stress leads to the oxidation of biomolecules such as lipids, proteins and nuclei acids. In this study, the oxidation of lipids, proteins and DNA was studied after the addition of hydrogen peroxide and Fenton reagent to cell suspension containing human leukemic monocyte lymphoma cell line U937. EPR spin-trapping data showed that the addition of hydrogen peroxide to the cell suspension formed hydroxyl radical via Fenton reaction mediated by endogenous metals. The malondialdehyde HPLC analysis showed no lipid peroxidation after the addition of hydrogen peroxide, whereas the Fenton reagent caused significant lipid peroxidation. The formation of protein carbonyls monitored by dot blot immunoassay and the DNA fragmentation measured by comet assay occurred after the addition of both hydrogen peroxide and Fenton reagent. Oxidative damage of biomolecules leads to the formation of singlet oxygen as conformed by EPR spin-trapping spectroscopy and the green fluorescence of singlet oxygen sensor green detected by confocal laser scanning microscopy. It is proposed here that singlet oxygen is formed by the decomposition of high-energy intermediates such as dioxetane or tetroxide formed by oxidative damage of biomolecules.

  8. Kombucha Tea Ameliorates Trichloroethylene Induced Hepatic Damages in Rats via Inhibition of Oxidative Stress and Free Radicals Induction

    International Nuclear Information System (INIS)

    Gharib, O.A.; Gharib, M.A.

    2008-01-01

    Kombucha Tea (KT) is reported to exhibit a wide variety of biological effects, including antioxidant. Evidence shows the important role of oxidative stress in the hepatic damage. The aim of this study is to investigate the possible protective effects of oral administration of KT in rats with trichloroethylene (TCE)-induced damage for ten consecutive days. Hepatic damage was evaluated by measuring total free radicals levels, biochemical and histological examinations. Serum gamma glutamyl transferase (GGT) activity (the hepatic damage marker), total protein, albumin and globulin as well as malonaldehyde (MDA), glutathione (GSH) content, nitric oxide (NO) concentration were evaluated in liver tissue homogenates. Total free radicals concentration in blood was examined by electron spin resonance (ESR). Total protein, DNA concentration, cell number and cell size in liver tissues were also examined. The rats orally administrated with TCE for ten days indicates hepatic damage changes, an increase in blood total free radicals concentration was observed, serum GGT activity, liver MDA, NO levels, total protein and decreased GSH content, DNA concentration and cell number. This accompanied with an increase in cell size of liver tissues, whereas KT reversed these effects. Furthermore, KT inhibits the concentration of total free radicals in blood and decreasing the increment of MDA and NO concentration. Histological studies reveal partial healing in those rats treated by KT after oral administration with TCE. The present results suggest that KT ameliorates TCE induced hepatic damage in rats probably due to its content of glucuronic, acetic acid and B vitamins via inhibition of oxidative stress and total free radicals

  9. Kinetic Study of Hydroxyl and Sulfate Radical-Mediated Oxidation of Pharmaceuticals in Wastewater Effluents.

    Science.gov (United States)

    Lian, Lushi; Yao, Bo; Hou, Shaodong; Fang, Jingyun; Yan, Shuwen; Song, Weihua

    2017-03-07

    Advanced oxidation processes (AOPs), such as hydroxyl radical (HO • )- and sulfate radical (SO 4 •- )-mediated oxidation, are alternatives for the attenuation of pharmaceuticals and personal care products (PPCPs) in wastewater effluents. However, the kinetics of these reactions needs to be investigated. In this study, kinetic models for 15 PPCPs were built to predict the degradation of PPCPs in both HO • - and SO 4 •- -mediated oxidation. In the UV/H 2 O 2 process, a simplified kinetic model involving only steady state concentrations of HO • and its biomolecular reaction rate constants is suitable for predicting the removal of PPCPs, indicating the dominant role of HO • in the removal of PPCPs. In the UV/K 2 S 2 O 8 process, the calculated steady state concentrations of CO 3 •- and bromine radicals (Br • , Br 2 •- and BrCl •- ) were 600-fold and 1-2 orders of magnitude higher than the concentrations of SO 4 •- , respectively. The kinetic model, involving both SO 4 •- and CO 3 •- as reactive species, was more accurate for predicting the removal of the 9 PPCPs, except for salbutamol and nitroimidazoles. The steric and ionic effects of organic matter toward SO 4 •- could lead to overestimations of the removal efficiencies of the SO 4 •- -mediated oxidation of nitroimidazoles in wastewater effluents.

  10. DNA damage and radical reactions: Mechanistic aspects, formation in cells and repair studies

    International Nuclear Information System (INIS)

    Cadet, J.; Ravanat, J.L.; Carell, T.; Cellai, L.; Chatgilialoglu, Ch.; Gimisis, Th.; Miranda, M.; O'Neill, P.; Robert, M.

    2008-01-01

    Several examples of oxidative and reductive reactions of DNA components that lead to single and tandem modifications are discussed in this review. These include nucleophilic addition reactions of the one-electron oxidation-mediated guanine radical cation and the one-electron reduced intermediate of 8-bromo-purine 2'-de-oxy-ribo-nucleosides that give rise to either an oxidizing guanine radical or related 5',8-cyclo-purine nucleosides. In addition, mechanistic insights into the reductive pathways involved in the photolyase induced reversal of cyclo-buta-cli-pyrimidine and pyrimidine (6-4) pyrimidone photoproducts are provided. Evidence for the occurrence and validation in cellular DNA of (OH) · radical degradation pathways of guanine that have been established in model systems has been gained from the accurate measurement of degradation products. Relevant information on biochemical aspects of the repair of single and clustered oxidatively generated damage to DNA has been gained from detailed investigations that rely on the synthesis of suitable modified probes. Thus the preparation of stable carbocyclic derivatives of purine nucleoside containing defined sequence oligonucleotides has allowed detailed crystallographic studies of the recognition step of the base damage by enzymes implicated in the base excision repair (BER) pathway. Detailed insights are provided on the BER processing of non-double strand break bi-stranded clustered damage that may consist of base lesions, a single strand break or abasic sites and represent one of the main deleterious classes of radiation-induced DNA damage. (authors)

  11. Processing of free radical damaged DNA bases

    International Nuclear Information System (INIS)

    Wallace, S.

    2003-01-01

    Free radicals produced during the radiolysis of water gives rise to a plethora of DNA damages including single strand breaks, sites of base loss and a wide variety of purine and pyrimidine base lesions. All these damages are processed in cells by base excision repair. The oxidative DNA glycosylases which catalyze the first step in the removal of a base damage during base excision repair evolved primarily to protect the cells from the deleterious mutagenic effects of single free radical-induced DNA lesions arising during oxidative metabolism. This is evidenced by the high spontaneous mutation rate in bacterial mutants lacking the oxidative DNA glycosylases. However, when a low LET photon transverses the DNA molecule, a burst of free radicals is produced during the radiolysis of water that leads to the formation of clustered damages in the DNA molecule, that are recognized by the oxidative DNA glycosylases. When substrates containing two closely opposed sugar damages or base and sugar damages are incubated with the oxidative DNA glycosylases in vitro, one strand is readily incised by the lyase activity of the DNA glycosylase. Whether or not the second strand is incised depends on the distance between the strand break resulting from the incised first strand and the remaining DNA lesion on the other strand. If the lesions are more than two or three base pairs apart, the second strand is readily cleaved by the DNA glycosylase, giving rise to a double strand break. Even if the entire base excision repair system is reconstituted in vitro, whether or not a double strand break ensues depends solely upon the ability of the DNA glycosylase to cleave the second strand. These data predicted that cells deficient in the oxidative DNA glycosylases would be radioresistant while those that overproduce an oxidative DNA glycosylase would be radiosensitive. This prediction was indeed borne in Escherichia coli that is, mutants lacking the oxidative DNA glycosylases are radioresistant

  12. Flavonoids as scavengers of nitric oxide radical.

    NARCIS (Netherlands)

    van Acker, S.A.B.E.; Tromp, M.N.J.L.; Haenen, G.R.M.M.; van der Vijgh, W.J.F.; Bast, A.

    1995-01-01

    Flavonoids are a group of naturally occurring compounds used, e.g., in the treatment of vascular endothelial damage. They are known to be excellent scavengers of oxygen free radicals. Since the nitric oxide radical (

  13. Daily grape juice consumption reduces oxidative DNA damage and plasma free radical levels in healthy Koreans

    International Nuclear Information System (INIS)

    Park, Yoo Kyoung; Park, Eunju; Kim, Jung-Shin; Kang, Myung-Hee

    2003-01-01

    Grape contains flavonoids with antioxidant properties which are believed to be protective against various types of cancer. This antioxidative protection is possibly provided by the effective scavenging of reactive oxygen species (ROS), thus defending cellular DNA from oxidative damage and potential mutations. This study of healthy adults tested whether a daily regimen of grape juice supplementation could reduce cellular DNA damage in peripheral lymphocytes and reduce the amount of free radicals released. Sixty-seven healthy volunteers (16 women and 51 men) aged 19-57 years were given 480 ml of grape juice daily for 8 weeks in addition to their normal diet, and blood samples were drawn before and after the intervention. The DNA damage was determined by using the single cell gel (comet) assay with alkaline electrophoresis and was quantified by measuring tail length (TL). Levels of free radicals were determined by reading the lucigenin-perborate ROS generating source, using the Ultra-Weak Chemiluminescence Analyzer System. Grape juice consumption resulted in a significant decrease in lymphocyte DNA damage expressed by TL (before supplementation: 88.75±1.55 μm versus after supplementation: 70.25±1.31 μm; P=0.000 by paired t-test). Additionally, grape juice consumption for 8 weeks reduced the ROS/photon count by 15%, compared to the beginning of the study. The preventive effect of grape juice against DNA damage was simultaneously shown in both sexes. These results indicate that the consumption of grape juice may increase plasma antioxidant capacity, resulting in reduced DNA damage in peripheral lymphocytes achieved at least partially by a reduced release of ROS. Our findings support the hypothesis that polyphenolic compounds contained in grape juice exert cancer-protective effects on lymphocytes, limiting oxidative DNA damage possibly via a decrease in free radical levels

  14. Daily grape juice consumption reduces oxidative DNA damage and plasma free radical levels in healthy Koreans

    Energy Technology Data Exchange (ETDEWEB)

    Park, Yoo Kyoung; Park, Eunju; Kim, Jung-Shin; Kang, Myung-Hee

    2003-08-28

    Grape contains flavonoids with antioxidant properties which are believed to be protective against various types of cancer. This antioxidative protection is possibly provided by the effective scavenging of reactive oxygen species (ROS), thus defending cellular DNA from oxidative damage and potential mutations. This study of healthy adults tested whether a daily regimen of grape juice supplementation could reduce cellular DNA damage in peripheral lymphocytes and reduce the amount of free radicals released. Sixty-seven healthy volunteers (16 women and 51 men) aged 19-57 years were given 480 ml of grape juice daily for 8 weeks in addition to their normal diet, and blood samples were drawn before and after the intervention. The DNA damage was determined by using the single cell gel (comet) assay with alkaline electrophoresis and was quantified by measuring tail length (TL). Levels of free radicals were determined by reading the lucigenin-perborate ROS generating source, using the Ultra-Weak Chemiluminescence Analyzer System. Grape juice consumption resulted in a significant decrease in lymphocyte DNA damage expressed by TL (before supplementation: 88.75{+-}1.55 {mu}m versus after supplementation: 70.25{+-}1.31 {mu}m; P=0.000 by paired t-test). Additionally, grape juice consumption for 8 weeks reduced the ROS/photon count by 15%, compared to the beginning of the study. The preventive effect of grape juice against DNA damage was simultaneously shown in both sexes. These results indicate that the consumption of grape juice may increase plasma antioxidant capacity, resulting in reduced DNA damage in peripheral lymphocytes achieved at least partially by a reduced release of ROS. Our findings support the hypothesis that polyphenolic compounds contained in grape juice exert cancer-protective effects on lymphocytes, limiting oxidative DNA damage possibly via a decrease in free radical levels.

  15. Hydroxyl radical formation and oxidative DNA damage induced by areca quid in vivo.

    Science.gov (United States)

    Chen, Chiu-Lan; Chi, Chin-Wen; Liu, Tsung-Yun

    2002-02-01

    Chewing areca quid (AQ) has been implicated as a major risk factor for the development of oral squamous-cell carcinoma (OSCC). Recent studies have suggested that AQ-generated reactive oxygen species (ROS) is one of the contributing factors for oral carcinogenesis. However, the AQ used in Taiwan is different from that used in other countries. This study is designed to test whether ROS are generated and the consequent effects in locally prepared AQ in vivo. We measured the hydroxyl radical formation, as represented by the presence of o- and m-tyrosine in saliva from volunteers who chewed AQ containing 20 mg phenylalanine. Their saliva contained significantly higher amounts (p betel leaf. We further tested the oxidative DNA damaging effect of the reconstituted AQ, as evidenced by the elevation of 8-hydroxy-2'-deoxyguanosine (8-OH-dG) levels, in hamster buccal pouch. Following daily painting for 14 d, the 8-OH-dG level in hamster buccal pouch is significantly elevated (p < .05) in the AQ-treated group versus the controls. These findings demonstrate that ROS, such as hydroxyl radical, are formed in the human oral cavity during AQ chewing, and chewing such prepared AQ might cause oxidative DNA damage to the surrounding tissues.

  16. Copper-mediated oxidative degradation of catecholamines and oxidative damage of protein

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, P.R.; Harria, M.I.N.; Felix, J.M.; Hoffmann, M.E. [Universidade Estadual de Campinas, SP (Brazil). Inst. de Biologia

    1997-12-31

    Full text. Degradative oxidation of catecholamines has been a matter of large interest in recent years due to the evidences associating their autoxidation with the etiology of neurotoxic and cardiotoxic processes. In this work we present data on the degradative oxidation of catecholamines of physiological importance: isoproterenol (IP), epinephrine (EP), norepinephrine (NEP), deoxyepinephrine (DEP) and dopamine (DA). The degradative oxidation of the catecholamines was followed by measurement of spectral changes and oxygen consumption by neutral aqueous solutions. The data show that Cu{sup 2+} strongly accelerated the rate of catecholamine oxidation, following the decreasing order; EP>DEP>IP>NEP>DA. The production of superoxide anion radical during catecholamine oxidation was very slow, even in the presence of Cu{sup 2+}. The ability of IP to induce damages on bovine serum albumin (BSA) was determined by measuring the formation of carbonyl-groups in the protein, detected by reduction with tritiated Na BH{sub 4}. The incubation of BSA with IP (50-500{mu}M), in the presence of 100{mu}M Cu{sup 2+} leaded to an increased and dose dependent {sup 3} H-incorporation by the oxidized protein. The production of oxidative damage by IP/Cu{sup 2+} was accompanied by marked BSA fragmentation, detected by SDS-polyacrylamide gel dependent (25-400{mu}M IP) des appearance of the original BSA band and appearance of smaller fragments spread in the gel, when incubation has been done in the presence of 100{mu}M Cu{sup 2+}. These results suggest that copper-catalysed oxidative degradation of proteins induced by catecholamines might be critically involved in the toxic action of these molecules

  17. Evaluation of Both Free Radical Scavenging Capacity and Antioxidative Damage Effect of Polydatin.

    Science.gov (United States)

    Jin, Ju; Li, Yan; Zhang, Xiuli; Chen, Tongsheng; Wang, Yifei; Wang, Zhiping

    Cellular damage such as oxidation and lipid peroxidation, and DNA damage induced by free-radicals like reactive oxygen species, has been implicated in several diseases. Radicals generated by 2,2-azobis (2-amidino-propane) dihydrochloride (AAPH) are similar to physiologically active ones. In this study we found that polydatin, a resveratrol natural precursor derived from many sources, has the capacity of free radical scavenging and antioxidative damage. Using free radical scavenging assays, the IC50 values of polydatin were 19.25 and 5.29 μg/ml with the DPPH and the ABTS assay, respectively, and 0.125 mg ferrous sulfate/1 mg polydatin with the FRAP assay. With the AAPH-induced oxidative injury cell model assay, polydatin showed a strong protective effect against the human liver tumor HepG2 cell oxidative stress damage. These results indicate that the antioxidant properties of polydatin have great potential for use as an alternative to more toxic synthetic antioxidants as an additive in food, cosmetics and pharmaceutical preparations for the treatment of oxidative diseases.

  18. Damage of polyesters by the atmospheric free radical oxidant NO3 •: a product study involving model systems

    Science.gov (United States)

    Goeschen, Catrin

    2013-01-01

    Summary Manufactured polymer materials are used in increasingly demanding applications, but their lifetime is strongly influenced by environmental conditions. In particular, weathering and ageing leads to dramatic changes in the properties of the polymers, which results in decreased service life and limited usage. Despite the heavy reliance of our society on polymers, the mechanism of their degradation upon exposure to environmental oxidants is barely understood. In this work, model systems of important structural motifs in commercial high-performing polyesters were used to study the reaction with the night-time free radical oxidant NO3 • in the absence and presence of other radical and non-radical oxidants. Identification of the products revealed ‘hot spots’ in polyesters that are particularly vulnerable to attack by NO3 • and insight into the mechanism of oxidative damage by this environmentally important radical. It is suggested that both intermediates as well as products of these reactions are potentially capable of promoting further degradation processes in polyesters under environmental conditions. PMID:24204400

  19. The role of proteins in damage induced by free radicals

    International Nuclear Information System (INIS)

    Gebicki, J.M.

    1996-01-01

    The initial consequence of oxidative stress in living organisms is chemical modification of cell components. Recently increasing attention in this area has been paid to the modification of proteins. A form of protein modification which has been studied in some detail only recently is peroxidation. In the last 8 years, we and our collaborators have shown that a range of isolated proteins acquire hydroperoxide groups when exposed to a range of biologically plausible oxidants. These include HO free radicals generated by radiation or in the Fenton reaction, peroxyl radicals, oxidants released by activated neutrophils, and peroxynitrite. In more complex systems, we also found protein peroxides in the apo B component of LDL treated with 20 μM Cu ++ , and in irradiated blood serum. These observations suggest that the formation of protein peroxides is a possible consequence of oxidative stress in vivo. A remarkable feature of the process of protein peroxidation is its high efficiency. This is most easily measured with proteins oxidized by radiation-generated free radicals. It was found that, for some proteins, peroxide yields reached 40% of the numbers of HO radicals generated. Thus in effect, almost half of these radicals can be converted to the much more long-lived protein peroxide groups. If they, in turn, have the capacity to damage other molecules, the major oxidative pathway in vivo may have the sequence: free radical ? protein peroxide ? another oxidized molecule. This hypothesis was tested by studying the ability of protein peroxides to react with selected molecules and the results are briefly discussed. Clearly, these effects are specific to individual proteins. More generally, amino acid and protein peroxides were found to be a potential source of a range of free radicals when reduced by Fe ++ . If this turns out to be a common phenomenon, protein peroxides may prove to be a major source of oxidative damage

  20. The role of proteins in damage induced by free radicals

    Energy Technology Data Exchange (ETDEWEB)

    Gebicki, J.M. [Macquarie Univ., North Ryde, NSW (Australia). School of Biological Sciences

    1996-12-31

    The initial consequence of oxidative stress in living organisms is chemical modification of cell components. Recently increasing attention in this area has been paid to the modification of proteins. A form of protein modification which has been studied in some detail only recently is peroxidation. In the last 8 years, we and our collaborators have shown that a range of isolated proteins acquire hydroperoxide groups when exposed to a range of biologically plausible oxidants. These include HO free radicals generated by radiation or in the Fenton reaction, peroxyl radicals, oxidants released by activated neutrophils, and peroxynitrite. In more complex systems, we also found protein peroxides in the apo B component of LDL treated with 20 {mu}M Cu{sup ++}, and in irradiated blood serum. These observations suggest that the formation of protein peroxides is a possible consequence of oxidative stress in vivo. A remarkable feature of the process of protein peroxidation is its high efficiency. This is most easily measured with proteins oxidized by radiation-generated free radicals. It was found that, for some proteins, peroxide yields reached 40% of the numbers of HO radicals generated. Thus in effect, almost half of these radicals can be converted to the much more long-lived protein peroxide groups. If they, in turn, have the capacity to damage other molecules, the major oxidative pathway in vivo may have the sequence: free radical ? protein peroxide ? another oxidized molecule. This hypothesis was tested by studying the ability of protein peroxides to react with selected molecules and the results are briefly discussed. Clearly, these effects are specific to individual proteins. More generally, amino acid and protein peroxides were found to be a potential source of a range of free radicals when reduced by Fe{sup ++}. If this turns out to be a common phenomenon, protein peroxides may prove to be a major source of oxidative damage.

  1. Watson-Crick Base Pair Radical Cation as a Model for Oxidative Damage in DNA.

    Science.gov (United States)

    Feketeová, Linda; Chan, Bun; Khairallah, George N; Steinmetz, Vincent; Maitre, Philippe; Radom, Leo; O'Hair, Richard A J

    2017-07-06

    The deleterious cellular effects of ionizing radiation are well-known, but the mechanisms causing DNA damage are poorly understood. The accepted molecular events involve initial oxidation and deprotonation at guanine sites, triggering hydrogen atom abstraction reactions from the sugar moieties, causing DNA strand breaks. Probing the chemistry of the initially formed radical cation has been challenging. Here, we generate, spectroscopically characterize, and examine the reactivity of the Watson-Crick nucleobase pair radical cation in the gas phase. We observe rich chemistry, including proton transfer between the bases and propagation of the radical site in deoxyguanosine from the base to the sugar, thus rupturing the sugar. This first example of a gas-phase model system providing molecular-level details on the chemistry of an ionized DNA base pair paves the way toward a more complete understanding of molecular processes induced by radiation. It also highlights the role of radical propagation in chemistry, biology, and nanotechnology.

  2. Occupational exposure to ionizing radiation as a risk factor for free-radicals mediated diseases

    International Nuclear Information System (INIS)

    Djurovic, B.; Spasic-Jokic, V.; Selakovic, V.

    2007-01-01

    Complete text of publication follows. It was experimentally showed, that the exposure to low doses of ionizing radiation (IR) result in over-production of oxygen derived free radicals with inverse dose-rate effect. The oxidative stress that follows, especially cell membrane damage, was considered by Petkau, as crucial step in the induction of radiation injuries. From clinical research and practice with other unexposed patients is known that this type of cell damage can lead to an impairment of cellular function and can cause many free-radicals mediated diseases, such as atherosclerosis, damage of heart muscles, inflammatory and immuno-reactive lesions, senile dementia, cancer, etc. The aim of this paper is to investigate if occupational exposure to low doses of IR change the redox status of exposed personnel, and if so, is it the additional risk factor for free-radicals mediated diseases. Subjects: 77 medical workers, devided in two groups: 44 occupationally exposed to ionizing radiation (E), and 33 controls (C), matched in age, gender, habits-daitary, alcohol consumption, smoking and exposure time, were examined. Methods: Radiation dose accumulated over years was calculated on the basis of individual TL-dose records. Superoxide-anion and MDA production, as well as SOD (MnSOD, CuZnSOD) and GSH activity were determined in blood samples spectrophotometrically. Results: Significantly higher incidence of cataract, and higher, but not significant, incidence of cardiovascular diseases was noticed in exposed. Our results also confirmed significantly higher superoxide and MDA production (p=0.0049, 0.000028, respectively), as well as, increased activity of MnSOD and CuZnSOD (p0.0105, 0.001, respectively), and decreased level of GSH (p=0.0599) in exposed. Conclusions: Our results showed that low doses of IR could induce oxidative stress and for that reason could be considered as additional risk factor for free radical-mediated diseases. Further epidemiological studies are

  3. Effect of curcumin against oxidation of biomolecules by hydroxyl radicals.

    Science.gov (United States)

    Borra, Sai Krishna; Mahendra, Jaideep; Gurumurthy, Prema; Jayamathi; Iqbal, Shabeer S; Mahendra, Little

    2014-10-01

    Among various reactive oxygen species, hydroxyl radicals have the strongest chemical activity, which can damage a wide range of essential biomolecules such as lipids, proteins, and DNA. The objective of this study was to investigate the beneficial effects of curcumin on prevention of oxidative damage of biomolecules by hydroxyl radicals generated in in vitro by a Fenton like reaction. We have incubated the serum, plasma and whole blood with H2O2/Cu2+/ Ascorbic acid system for 4 hours at 37 0C and observed the oxidation of biomolecules like albumin, lipids, proteins and DNA. Curcumin at the concentrations of 50,100 and 200 μmoles, prevented the formation of ischemia modified albumin, MDA, protein carbonyls, oxidized DNA and increased the total antioxidant levels and GSH significantly. These observations suggest the hydroxyl radical scavenging potentials of curcumin and protective actions to prevent the oxidation of biomolecules by hydroxyl radicals.

  4. Evaluation of free radical scavenging capacity and antioxidative damage effect of resveratrol-nanostructured lipid carriers

    Science.gov (United States)

    Jin, Ju; Shi, Fan; Li, Qiu-wen; Li, Pei-shan; Chen, Tong-sheng; Wang, Yi-fei; Wang, Zhi-ping

    2016-03-01

    Cellular damage induced by free-radicals like reactive oxygen species has been implicated in several diseases. 2, 2-azobis(2-amidino-propane) dihydrochloride(AAPH) generates two potent ROS capable of inducing lipid peroxidation: alkoxy radical(RO-) and peroxy radical(ROO-). These radicals are similar to those that are physiologically active and thus might initiate a cascade of intracellular toxic events leading to oxidation, lipid peroxidation, DNA damage and subsequent cell death. Hence naturally anti-oxidant play a vital role in combating these conditions. In this study, resveratrol loaded nanostructured lipid carriers (Res-NLC) was prepared by hot melting and then high pressure homogenization technique. The effects of Res-NLC on free radical scavenging capacity and antioxidative damage is investigated. The particle size and zeta potential of Res-NLC were 139.3 ± 1.7 nm and -11.21 ± 0.41 mV, respectively. By free radical scavenging assays, the IC50 value of Res-NLC were 19.25, 5.29 μg/mL with DPPH, ABTS assay respectively, and 0.161 mg ferrous sulfate/1 mg Res-NLC with FRAP assay; and by AAPH-induced oxidative injury cell model assay, Res-NLC showed the strong protective effect against the human liver tumor HepG2 cell oxidative stress damage. These results indicated that the antioxidant properties of Res-NLC hold great potential used as an alternative to more toxic synthetic antioxidants as an additive in food, cosmetic and pharmaceutical preparations for the oxidative diseases treatment.

  5. A novel theory: biological processes mostly involve two types of mediators, namely general and specific mediators Endogenous small radicals such as superoxide and nitric oxide may play a role of general mediator in biological processes.

    Science.gov (United States)

    Mo, Jian

    2005-01-01

    A great number of papers have shown that free radicals as well as bioactive molecules can play a role of mediator in a wide spectrum of biological processes, but the biological actions and chemical reactivity of the free radicals are quite different from that of the bioactive molecules, and that a wide variety of bioactive molecules can be easily modified by free radicals due to having functional groups sensitive to redox, and the significance of the interaction between the free radicals and the bioactive molecules in biological processes has been confirmed by the results of some in vitro and in vivo studies. Based on these evidence, this article presented a novel theory about the mediators of biological processes. The essentials of the theory are: (a) mediators of biological processes can be classified into general and specific mediators; the general mediators include two types of free radicals, namely superoxide and nitric oxide; the specific mediators include a wide variety of bioactive molecules, such as specific enzymes, transcription factors, cytokines and eicosanoids; (b) a general mediator can modify almost any class of the biomolecules, and thus play a role of mediator in nearly every biological process via diverse mechanisms; a specific mediator always acts selectively on certain classes of the biomolecules, and may play a role of mediator in different biological processes via a same mechanism; (c) biological processes are mostly controlled by networks of their mediators, so the free radicals can regulate the last consequence of a biological process by modifying some types of the bioactive molecules, or in cooperation with these bioactive molecules; the biological actions of superoxide and nitric oxide may be synergistic or antagonistic. According to this theory, keeping the integrity of these networks and the balance between the free radicals and the bioactive molecules as well as the balance between the free radicals and the free radical scavengers

  6. Direct evidence of iNOS-mediated in vivo free radical production and protein oxidation in acetone-induced ketosis

    Science.gov (United States)

    Stadler, Krisztian; Bonini, Marcelo G.; Dallas, Shannon; Duma, Danielle; Mason, Ronald P.; Kadiiska, Maria B.

    2008-01-01

    Diabetic patients frequently encounter ketosis that is characterized by the breakdown of lipids with the consequent accumulation of ketone bodies. Several studies have demonstrated that reactive species are likely to induce tissue damage in diabetes, but the role of the ketone bodies in the process has not been fully investigated. In this study, electron paramagnetic resonance (EPR) spectroscopy combined with novel spin-trapping and immunological techniques has been used to investigate in vivo free radical formation in a murine model of acetone-induced ketosis. A six-line EPR spectrum consistent with the α-(4-pyridyl-1-oxide)-N-t-butylnitrone radical adduct of a carbon-centered lipid-derived radical was detected in the liver extracts. To investigate the possible enzymatic source of these radicals, inducible nitric oxide synthase (iNOS) and NADPH oxidase knockout mice were used. Free radical production was unchanged in the NADPH oxidase knockout but much decreased in the iNOS knockout mice, suggesting a role for iNOS in free radical production. Longer-term exposure to acetone revealed iNOS overexpression in the liver together with protein radical formation, which was detected by confocal microscopy and a novel immunospin-trapping method. Immunohistochemical analysis revealed enhanced lipid peroxidation and protein oxidation as a consequence of persistent free radical generation after 21 days of acetone treatment in control and NADPH oxidase knockout but not in iNOS knockout mice. Taken together, our data demonstrate that acetone administration, a model of ketosis, can lead to protein oxidation and lipid peroxidation through a free radical-dependent mechanism driven mainly by iNOS overexpression. PMID:18559982

  7. Oxidation of free, peptide and protein tryptophan residues mediated by AAPH-derived free radicals: role of alkoxyl and peroxyl radicals

    DEFF Research Database (Denmark)

    Fuentes-Lemus, E.; Dorta, E.; Escobar, E.

    2016-01-01

    The oxidation of tryptophan (Trp) residues, mediated by peroxyl radicals (ROOc), follows a complex mechanism involving free radical intermediates, and short chain reactions. The reactivity of Trp towards ROOc should be strongly affected by its inclusion in peptides and proteins. To examine...... the latter, we investigated (by fluorescence) the kinetic of the consumption of free, peptide- and protein-Trp residues towards AAPH (2,20 -azobis(2-amidinopropane)dihydrochloride)-derived free radicals. Interestingly, the initial consumption rates (Ri ) were only slightly influenced by the inclusion of Trp...... concentrations (10–50 mM), the values of Ri were nearly constant; and at high Trp concentrations (50 mM to 1 mM), a slower increase of Ri than expected for chain reactions. Similar behavior was detected for all three systems (free Trp, and Trp in peptides and proteins). For the first time we are showing...

  8. Prevention of dopaminergic neurotoxicity by targeting nitric oxide and peroxynitrite: implications for the prevention of methamphetamine-induced neurotoxic damage.

    Science.gov (United States)

    Imam, S Z; Islam, F; Itzhak, Y; Slikker, W; Ali, S F

    2000-09-01

    Methamphetamine (METH) is a neurotoxic psychostimulant that produces catecholaminergic brain damage by producing oxidative stress and free radical generation. The role of oxygen and nitrogen radicals is well documented as a cause of METH-induced neurotoxic damage. In this study, we have obtained evidence that METH-induced neurotoxicity is the resultant of interaction between oxygen and nitrogen radicals, and it is mediated by the production of peroxynitrite. We have also assessed the effects of inhibitors of neuronal nitric oxide synthase (nNOS) as well as scavenger of nitric oxide and a peroxynitrite decomposition catalyst. Significant protective effects were observed with the inhibitor of nNOS, 7-nitroindazole (7-NI), as well as by the selective peroxynitrite scavenger or decomposition catalyst, 5,10,15,20-tetrakis(2,4,6-trimethyl-3,5-sulfonatophenyl)porphyrinato iron III (FeTPPS). However, the use of a nitric oxide scavenger, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO), did not provide any significant protection against METH-induced hyperthermia or peroxynitrite generation and the resulting dopaminergic neurotoxicity. In particular, treatment with FeTPPS completely prevented METH-induced hyperthermia, peroxynitrite production, and METH-induced dopaminergic depletion. Together, these data demonstrate that METH-induced dopaminergic neurotoxicity is mediated by the generation of peroxynitrite, which can be selectively protected by nNOS inhibitors or peroxynitrite scavenger or decomposition catalysts.

  9. Shape-dependent bactericidal activity of copper oxide nanoparticle mediated by DNA and membrane damage

    International Nuclear Information System (INIS)

    Laha, Dipranjan; Pramanik, Arindam; Laskar, Aparna; Jana, Madhurya; Pramanik, Panchanan; Karmakar, Parimal

    2014-01-01

    Highlights: • Spherical and sheet shaped copper oxide nanoparticles were synthesized. • Physical characterizations of these nanoparticles were done by TEM, DLS, XRD, FTIR. • They showed shape dependent antibacterial activity on different bacterial strain. • They induced both membrane damage and ROS mediated DNA damage in bacteria. - Abstract: In this work, we synthesized spherical and sheet shaped copper oxide nanoparticles and their physical characterizations were done by the X-ray diffraction, fourier transform infrared spectroscopy, transmission electron microscopy and dynamic light scattering. The antibacterial activity of these nanoparticles was determined on both gram positive and gram negative bacterial. Spherical shaped copper oxide nanoparticles showed more antibacterial property on gram positive bacteria where as sheet shaped copper oxide nanoparticles are more active on gram negative bacteria. We also demonstrated that copper oxide nanoparticles produced reactive oxygen species in both gram negative and gram positive bacteria. Furthermore, they induced membrane damage as determined by atomic force microscopy and scanning electron microscopy. Thus production of and membrane damage are major mechanisms of the bactericidal activity of these copper oxide nanoparticles. Finally it was concluded that antibacterial activity of nanoparticles depend on physicochemical properties of copper oxide nanoparticles and bacterial strain

  10. Shape-dependent bactericidal activity of copper oxide nanoparticle mediated by DNA and membrane damage

    Energy Technology Data Exchange (ETDEWEB)

    Laha, Dipranjan; Pramanik, Arindam [Department of Life Science and Biotechnology, Jadavpur University, 188, Raja S C Mallick Road, Kolkata 700032 (India); Laskar, Aparna [CSIR-Indian Institute of Chemical Biology, Kolkata 700032 (India); Jana, Madhurya [Department of Life Science and Biotechnology, Jadavpur University, 188, Raja S C Mallick Road, Kolkata 700032 (India); Pramanik, Panchanan [Department of Chemistry, Indian Institute of Technology, Kharagpur 721302 (India); Karmakar, Parimal, E-mail: pkarmakar_28@yahoo.co.in [Department of Life Science and Biotechnology, Jadavpur University, 188, Raja S C Mallick Road, Kolkata 700032 (India)

    2014-11-15

    Highlights: • Spherical and sheet shaped copper oxide nanoparticles were synthesized. • Physical characterizations of these nanoparticles were done by TEM, DLS, XRD, FTIR. • They showed shape dependent antibacterial activity on different bacterial strain. • They induced both membrane damage and ROS mediated DNA damage in bacteria. - Abstract: In this work, we synthesized spherical and sheet shaped copper oxide nanoparticles and their physical characterizations were done by the X-ray diffraction, fourier transform infrared spectroscopy, transmission electron microscopy and dynamic light scattering. The antibacterial activity of these nanoparticles was determined on both gram positive and gram negative bacterial. Spherical shaped copper oxide nanoparticles showed more antibacterial property on gram positive bacteria where as sheet shaped copper oxide nanoparticles are more active on gram negative bacteria. We also demonstrated that copper oxide nanoparticles produced reactive oxygen species in both gram negative and gram positive bacteria. Furthermore, they induced membrane damage as determined by atomic force microscopy and scanning electron microscopy. Thus production of and membrane damage are major mechanisms of the bactericidal activity of these copper oxide nanoparticles. Finally it was concluded that antibacterial activity of nanoparticles depend on physicochemical properties of copper oxide nanoparticles and bacterial strain.

  11. Ultraviolet radiation-mediated damage to cellular DNA

    International Nuclear Information System (INIS)

    Cadet, Jean; Sage, Evelyne; Douki, Thierry

    2005-01-01

    Emphasis is placed in this review article on recent aspects of the photochemistry of cellular DNA in which both the UVB and UVA components of solar radiation are implicated individually or synergistically. Interestingly, further mechanistic insights into the UV-induced formation of DNA photoproducts were gained from the application of new accurate and sensitive chromatographic and enzymic assays aimed at measuring base damage. Thus, each of the twelve possible dimeric photoproducts that are produced at the four main bipyrimidine sites can now be singled out as dinucleoside monophosphates that are enzymatically released from UV-irradiated DNA. This was achieved using a recently developed high-performance liquid chromatography-tandem mass spectrometry assay (HPLC-MS/MS) assay after DNA extraction and appropriate enzymic digestion. Interestingly, a similar photoproduct distribution pattern is observed in both isolated and cellular DNA upon exposure to low doses of either UVC or UVB radiation. This applies more specifically to the DNA of rodent and human cells, the cis-syn cyclobutadithymine being predominant over the two other main photolesions, namely thymine-cytosine pyrimidine (6-4) pyrimidone adduct and the related cyclobutyl dimer. UVA-irradiation was found to generate cyclobutane dimers at TT and to a lower extent at TC sites as a likely result of energy transfer mechanism involving still unknown photoexcited chromophore(s). Oxidative damage to DNA is also induced although less efficiently by UVA-mediated photosensitization processes that mostly involved 1 O 2 together with a smaller contribution of hydroxyl radical-mediated reactions through initially generated superoxide radicals

  12. Laccase catalyzed grafting of-N-OH type mediators to lignin via radical-radical coupling

    DEFF Research Database (Denmark)

    Munk, Line; Punt, A. M.; Kabel, M. A.

    2017-01-01

    Lignin is an underexploited resource in biomass refining. Laccases (EC 1.10.3.2) catalyze oxidation of phenolic hydroxyls using O2 as electron acceptor and may facilitate lignin modification in the presence of mediators. This study assessed the reactivity of four different synthetic mediators...... better than HBT (1-hydroxybenzotriazole). Three different mechanisms are suggested to explain the grafting of HPI and HBT, all involving radical-radical coupling to produce covalent bonding to lignin. Lignin from exhaustive cellulase treatment of wheat straw was more susceptible to grafting than beech...... organosolv lignin with the relative abundance of grafting being 35% vs. 11% for HPI and 5% vs. 1% for HBT on these lignin substrates. The data imply that lignin can be functionalized via laccase catalysis with-N-OH type mediators....

  13. Oxidative DNA damage & repair: An introduction.

    Science.gov (United States)

    Cadet, Jean; Davies, Kelvin J A

    2017-06-01

    This introductory article should be viewed as a prologue to the Free Radical Biology & Medicine Special Issue devoted to the important topic of Oxidatively Damaged DNA and its Repair. This special issue is dedicated to Professor Tomas Lindahl, co-winner of the 2015 Nobel Prize in Chemistry for his seminal discoveries in the area repair of oxidatively damaged DNA. In the past several years it has become abundantly clear that DNA oxidation is a major consequence of life in an oxygen-rich environment. Concomitantly, survival in the presence of oxygen, with the constant threat of deleterious DNA mutations and deletions, has largely been made possible through the evolution of a vast array of DNA repair enzymes. The articles in this Oxidatively Damaged DNA & Repair special issue detail the reactions by which intracellular DNA is oxidatively damaged, and the enzymatic reactions and pathways by which living organisms survive such assaults by repair processes. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Role of Free Radicals, Oxidative Stress and Xenobiotics in Carcinogenesis by Environmental Pollutants

    Directory of Open Access Journals (Sweden)

    Dibyajyoti Saha

    2014-09-01

    Full Text Available Carcinogenesis by many small molecular weight chemicals involves either a direct action of the chemical on cellular DNA or metabolism of the parent chemical to an active or ultimate form, which can than react with cellular DNA to produce a permanent chemical change in a DNA structure. A free radical is an atom or molecule that has one or more unpaired electron(s. These are highly reactive species capable of wide spread, indiscriminate oxidation and per oxidation of proteins, lipids and DNA which can lead to significant cellular damage and even tissue and/or organ failure. . Oxidative stress is a leading cause to damage cells by oxidation. The rate at which oxidative damage is induced (input and the rate at which it is efficiently repaired and removed (output. Xenobiotics are a compound that is foreign to the body. Xenobiotics can produce a variety of biological effects, including pharmacologic responses, toxicity, genes, immunologic reactions and cancer. Oxidative stress is a leading cause to damage cells by oxidation. The rate at which oxidative damage is induced (input and the rate at which it is efficiently repaired and removed (output. This communication highlights the role of carcinogens as environmental pollutants with the possible mechanism of free radicals, oxidative stress and xenobiotics.

  15. Free Radical Damage in Ischemia-Reperfusion Injury: An Obstacle in Acute Ischemic Stroke after Revascularization Therapy

    Directory of Open Access Journals (Sweden)

    Ming-Shuo Sun

    2018-01-01

    Full Text Available Acute ischemic stroke is a common cause of morbidity and mortality worldwide. Thrombolysis with recombinant tissue plasminogen activator and endovascular thrombectomy are the main revascularization therapies for acute ischemic stroke. However, ischemia-reperfusion injury after revascularization therapy can result in worsening outcomes. Among all possible pathological mechanisms of ischemia-reperfusion injury, free radical damage (mainly oxidative/nitrosative stress injury has been found to play a key role in the process. Free radicals lead to protein dysfunction, DNA damage, and lipid peroxidation, resulting in cell death. Additionally, free radical damage has a strong connection with inducing hemorrhagic transformation and cerebral edema, which are the major complications of revascularization therapy, and mainly influencing neurological outcomes due to the disruption of the blood-brain barrier. In order to get a better clinical prognosis, more and more studies focus on the pharmaceutical and nonpharmaceutical neuroprotective therapies against free radical damage. This review discusses the pathological mechanisms of free radicals in ischemia-reperfusion injury and adjunctive neuroprotective therapies combined with revascularization therapy against free radical damage.

  16. DNA Binding Hydroxyl Radical Probes

    OpenAIRE

    Tang, Vicky J; Konigsfeld, Katie M; Aguilera, Joe A; Milligan, Jamie R

    2012-01-01

    The hydroxyl radical is the primary mediator of DNA damage by the indirect effect of ionizing radiation. It is a powerful oxidizing agent produced by the radiolysis of water and is responsible for a significant fraction of the DNA damage associated with ionizing radiation. There is therefore an interest in the development of sensitive assays for its detection. The hydroxylation of aromatic groups to produce fluorescent products has been used for this purpose. We have examined four different c...

  17. IRON AND FREE RADICAL OXIDATIONS IN CELL MEMBRANES

    Science.gov (United States)

    Schafer, Freya Q.; Yue Qian, Steven; Buettner, Garry R.

    2013-01-01

    Brain tissue being rich in polyunsaturated fatty acids, is very susceptible to lipid peroxidation. Iron is well known to be an important initiator of free radical oxidations. We propose that the principal route to iron-mediated lipid peroxidations is via iron-oxygen complexes rather than the reaction of iron with hydrogen peroxide, the Fenton reaction. To test this hypothesis, we enriched leukemia cells (K-562 and L1210 cells) with docosahexaenoic acid (DHA) as a model for brain tissue, increasing the amount of DHA from approximately 3 mole % to 32 mole %. These cells were then subjected to ferrous iron and dioxygen to initiate lipid peroxidation in the presence or absence of hydrogen peroxide. Lipid-derived radicals were detected using EPR spin trapping with α-(4-pyridyl-1-oxide)-N-t-butylnitrone (POBN). As expected, lipid-derived radical formation increases with increasing cellular lipid unsaturation. Experiments with Desferal demonstrate that iron is required for the formation of lipid radicals from these cells. Addition of iron to DHA-enriched L1210 cells resulted in significant amounts of radical formation; radical formation increased with increasing amount of iron. However, the exposure of cells to hydrogen peroxide before the addition of ferrous iron did not increase cellular radical formation, but actually decreased spin adduct formation. These data suggest that iron-oxygen complexes are the primary route to the initiation of biological free radical oxidations. This model proposes a mechanism to explain how catalytic iron in brain tissue can be so destructive. PMID:10872752

  18. Superoxide dismutase 1-mediated production of ethanol- and DNA-derived radicals in yeasts challenged with hydrogen peroxide: molecular insights into the genome instability of peroxiredoxin-null strains.

    Science.gov (United States)

    Ogusucu, Renata; Rettori, Daniel; Netto, Luis E S; Augusto, Ohara

    2009-02-27

    Peroxiredoxins are receiving increasing attention as defenders against oxidative damage and sensors of hydrogen peroxide-mediated signaling events. In the yeast Saccharomyces cerevisiae, deletion of one or more isoforms of the peroxiredoxins is not lethal but compromises genome stability by mechanisms that remain under scrutiny. Here, we show that cytosolic peroxiredoxin-null cells (tsa1Deltatsa2Delta) are more resistant to hydrogen peroxide than wild-type (WT) cells and consume it faster under fermentative conditions. Also, tsa1Deltatsa2Delta cells produced higher yields of the 1-hydroxyethyl radical from oxidation of the glucose metabolite ethanol, as proved by spin-trapping experiments. A major role for Fenton chemistry in radical formation was excluded by comparing WT and tsa1Deltatsa2Delta cells with respect to their levels of total and chelatable metal ions and of radical produced in the presence of chelators. The main route for 1-hydroxyethyl radical formation was ascribed to the peroxidase activity of Cu,Zn-superoxide dismutase (Sod1), whose expression and activity increased approximately 5- and 2-fold, respectively, in tsa1Deltatsa2Delta compared with WT cells. Accordingly, overexpression of human Sod1 in WT yeasts led to increased 1-hydroxyethyl radical production. Relevantly, tsa1Deltatsa2Delta cells challenged with hydrogen peroxide contained higher levels of DNA-derived radicals and adducts as monitored by immuno-spin trapping and incorporation of (14)C from glucose into DNA, respectively. The results indicate that part of hydrogen peroxide consumption by tsa1Deltatsa2Delta cells is mediated by induced Sod1, which oxidizes ethanol to the 1-hydroxyethyl radical, which, in turn, leads to increased DNA damage. Overall, our studies provide a pathway to account for the hypermutability of peroxiredoxin-null strains.

  19. Oxidative Stress-Mediated Aging during the Fetal and Perinatal Periods

    Directory of Open Access Journals (Sweden)

    Lucia Marseglia

    2014-01-01

    Full Text Available Oxidative stress is worldwide recognized as a fundamental component of the aging, a process that begins before birth. There is a critical balance between free radical generation and antioxidant defenses. Oxidative stress is caused by an imbalance between the production of free radicals and the ability of antioxidant system to detoxify them. Oxidative stress can occur early in pregnancy and continue in the postnatal period; this damage is implicated in the pathophysiology of pregnancy-related disorders, including recurrent pregnancy loss, preeclampsia and preterm premature rupture of membranes. Moreover, diseases of the neonatal period such as bronchopulmonary dysplasia, retinopathy of prematurity, necrotizing enterocolitis, and periventricular leukomalacia are related to free radical damage. The specific contribution of oxidative stress to the pathogenesis and progression of these neonatal diseases is only partially understood. This review summarizes what is known about the role of oxidative stress in pregnancy and in the pathogenesis of common disorders of the newborn, as a component of the early aging process.

  20. Cell-mediated reduction of protein and peptide hydroperoxides to reactive free radicals

    DEFF Research Database (Denmark)

    Headlam, Henrietta A; Davies, Michael Jonathan

    2003-01-01

    Radical attack on proteins in the presence of O(2) gives protein hydroperoxides in high yields. These peroxides are decomposed by transition metal ions, reducing agents, UV light and heat, with the formation of a range of reactive radicals that are capable of initiating further damage. Evidence has...... been presented for the formation of alcohols as stable products of peroxide decomposition, and these have been employed as markers of oxidative damage in vivo. The mechanism of formation of these alcohols is unclear, with both radical and nonradical pathways capable of generating these products....... In this study we have investigated the reduction of peptide and protein hydroperoxides by THP-1 (human monocyte-like) cells and it is shown that this process is accompanied by radical formation as detected by EPR spin trapping. The radicals detected, which are similar to those detected from metal-ion catalyzed...

  1. Radio-oxidative membrane damage and its possible role as an indicator of radiation exposure

    International Nuclear Information System (INIS)

    Amit Kumar; Pandey, B.N.; Mishra, K.P.

    2004-01-01

    Cellular membranes have been recognized as a sensitive target in the mechanism of ionizing radiation-induced cell killing. In our laboratory, studies have been devoted to investigations on gamma radiation induced oxidative damage to model and cellular membrane damage by employing fluorescence and electron spin resonance (ESR) methods Considerable evidences has accumulated to suggest that radiation induced oxidative damage was related to apoptotic death of a variety of cells in culture. Radiation induced damage involving lipid peroxidation, altered bilayer fluidity, permeability changes and intracellular generated ROS have been evaluated by chemical and physical methods. Modification of damage by structural modulating agents such as cholesterol and antioxidants such as eugenol, ascorbic acid, ellagic acid, triphala have been extensively investigated. Generation of intracellular ROS in radiation stressed normal cell e.g. mouse thymocytes, tumor cells e.g. Ehrlich ascites cells and human cervical cell line were evaluated after exposure from low to moderate doses of α-radiation. Results suggest that modulation of intracellular ROS level may be an important approach to alter radio-cytotoxicity of cells. This presentation would describe results of our study together with an overview of free radical mediated oxidative damage to cellular membrane as an indicator of radiation exposure. (author)

  2. Evidence for radical-oxidation of plasma proteins in humans

    International Nuclear Information System (INIS)

    Wang, D.; Davies, M.; Dean, R.; Fu, S.; Taurins, A.; Sullivans, D.

    1998-01-01

    Oxidation of proteins by radicals has been implicated in many pathological processes. The hydroxyl radical is known to generate protein-bound hydroxylated derivatives of amino acids, for example hydroxyvaline (from Val), hydroxyleucine (from Leu), o-tyrosine (from Phe), and DOPA (from Tyr). In this study, we have investigated the occurrence of these oxidised amino acids in human plasma proteins from both normal subjects and dialysis patients. By employing previously established HPLC methods [Fu et al. Biochemical Journal, 330, 233-239, 1998], we have found that oxidised amino acids exist in normal human plasma proteins (n=32). The level of these oxidised amino acids is not correlated to age. Similar levels of oxidised amino acids are found in the plasma proteins of the dialysis patients (n=6), but a more detailed survey is underway. The relative abundance of the oxidised amino acids is similar to that resulting from oxidation of BSA by hydroxy radicals or Fenton systems [Fu et al. Biochemical Journal, 333, 519-525, 1998]. The results suggest that metal-ion catalysed oxyl-radical chemistry may be a key contributor to the oxidative damage in plasma proteins in vivo in humans

  3. Modulation of oxidative damage by nitroxide free radicals.

    Science.gov (United States)

    Dragutan, Ileana; Mehlhorn, Rolf J

    2007-03-01

    Piperidine nitroxides like 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) are persistent free radicals in non-acidic aqueous solutions and organic solvents that may have value as therapeutic agents in medicine. In biological environments, they undergo mostly reduction to stable hydroxylamines but can also undergo oxidation to reactive oxoammonium compounds. Reactions of the oxoammonium derivatives could have adverse consequences including chemical modification of vital macromolecules and deleterious effects on cell signaling. An examination of their reactivity in aqueous solution has shown that oxoammonium compounds can oxidize almost any organic as well as many inorganic molecules found in biological systems. Many of these reactions appear to be one-electron transfers that reduce the oxoammonium to the corresponding nitroxide species, in contrast to a prevalence of two-electron reductions of oxoammonium in organic solvents. Amino acids, alcohols, aldehydes, phospholipids, hydrogen peroxide, other nitroxides, hydroxylamines, phenols and certain transition metal ions and their complexes are among reductants of oxoammonium, causing conversion of this species to the paramagnetic nitroxide. On the other hand, thiols and oxoammonium yield products that cannot be detected by ESR even under conditions that would oxidize hydroxylamines to nitroxides. These products may include hindered secondary amines, sulfoxamides and sulfonamides. Thiol oxidation products other than disulfides cannot be restored to thiols by common enzymatic reduction pathways. Such products may also play a role in cell signaling events related to oxidative stress. Adverse consequences of the reactions of oxoammonium compounds may partially offset the putative beneficial effects of nitroxides in some therapeutic settings.

  4. Mitochondrial DNA damage and oxidative damage in HL-60 cells exposed to 900 MHz radiofrequency fields

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yulong; Zong, Lin; Gao, Zhen [School of Public Health, Soochow University, Suzhou, Jiangsu Province (China); Zhu, Shunxing [Laboratory Animal Center, Nantong University, Nantong, Jiangsu Province (China); Tong, Jian [School of Public Health, Soochow University, Suzhou, Jiangsu Province (China); Cao, Yi, E-mail: yicao@suda.edu.cn [School of Public Health, Soochow University, Suzhou, Jiangsu Province (China)

    2017-03-15

    Highlights: • Increased reactive oxygen species. • Decreased mitochondrial transcription Factor A and polymerase gamma. • Decreased mitochondrial transcripts (ND1 and 16S) and mtDNA copy number. • Increased 8-hydroxy-2′deoxyguanosine. • Decreased adenosine triphosphate. - Abstract: HL-60 cells, derived from human promyelocytic leukemia, were exposed to continuous wave 900 MHz radiofrequency fields (RF) at 120 μW/cm{sup 2} power intensity for 4 h/day for 5 consecutive days to examine whether such exposure is capable damaging the mitochondrial DNA (mtDNA) mediated through the production of reactive oxygen species (ROS). In addition, the effect of RF exposure was examined on 8-hydroxy-2′-dexoyguanosine (8-OHdG) which is a biomarker for oxidative damage and on the mitochondrial synthesis of adenosine triphosphate (ATP) which is the energy required for cellular functions. The results indicated a significant increase in ROS and significant decreases in mitochondrial transcription factor A, mtDNA polymerase gamma, mtDNA transcripts and mtDNA copy number in RF-exposed cells compared with those in sham-exposed control cells. In addition, there was a significant increase in 8-OHdG and a significant decrease in ATP in RF-exposed cells. The response in positive control cells exposed to gamma radiation (GR, which is also known to induce ROS) was similar to those in RF-exposed cells. Thus, the overall data indicated that RF exposure was capable of inducing mtDNA damage mediated through ROS pathway which also induced oxidative damage. Prior-treatment of RF- and GR-exposed the cells with melatonin, a well-known free radical scavenger, reversed the effects observed in RF-exposed cells.

  5. Total free radical species and oxidation equivalent in polluted air.

    Science.gov (United States)

    Wang, Guoying; Jia, Shiming; Niu, Xiuli; Tian, Haoqi; Liu, Yanrong; Chen, Xuefu; Li, Lan; Zhang, Yuanhang; Shi, Gaofeng

    2017-12-31

    Free radicals are the most important chemical intermediate or agent of the atmosphere and influenced by thousands of reactants. The free radicals determine the oxidizing power of the polluted air. Various gases present in smog or haze are oxidants and induce organ and cellular damage via generation of free radical species. At present, however, the high variability of total free radicals in polluted air has prevented the detection of possible trends or distributions in the concentration of those species. The total free radicals are a kind of contaminants with colorless, tasteless characteristics, and almost imperceptible by human body. Here we present total free radical detection and distribution characteristics, and analyze the effects of total free radicals in polluted air on human health. We find that the total free radical values can be described by not only a linear dependence on ozone at higher temperature period, but also a linear delay dependence on particulate matter at lower temperature period throughout the measurement period. The total free radical species distribution is decrease from west to east in Lanzhou, which closely related to the distribution of the air pollutants. The total free radical oxidation capacity in polluted air roughly matches the effects of tobacco smoke produced by the incomplete combustion of a controlled amount of tobacco in a smoke chamber. A relatively unsophisticated chromatographic fingerprint similarity is used for indicating preliminarily the effect of total free radicals in polluted air on human health. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Evaluation of the Genotoxic Potential against H2O2-Radical-Mediated DNA Damage and Acute Oral Toxicity of Standardized Extract of Polyalthia longifolia Leaf

    Directory of Open Access Journals (Sweden)

    Subramanion L. Jothy

    2013-01-01

    Full Text Available Medicinal plants have been used in medicoculturally diverse countries around the world, where it is a part of a time-honoured tradition that is respected even today. Polyalthia longifolia leaf extract has been previously reported as an efficient antioxidant in vitro. Hence, the genotoxic effects of P. longifolia leaf were investigated by using plasmid relation, comet, and Allium cepa assay. In the presence of  ∙OH radicals, the DNA in supercoil was start nicked into open circular form, which is the product of the single-stranded cleavage of supercoil DNA and quantified as fragmented separate bands on agarose gel in plasmid relation assay. In the plasmid relation and comet assay, the P. longifolia leaf extract exhibited strong inhibitory effects against H2O2-mediated DNA damage. A dose-dependent increase of chromosome aberrations was also observed in the Allium cepa assay. The abnormalities scored were stickiness, c-mitosis, bridges, and vagrant chromosomes. Micronucleated cells were also observed at the interphase. The results of Allium cepa assay confirmed that the methanol extracts of P. longifolia exerted no significant genotoxic or mitodepressive effects at 100 μg/mL. Thus, this study demonstrated that P. longifolia leaf extract has a beneficial effect against oxidative DNA damage. This experiment is the first report for the protective effect of P. longifolia on DNA damage-induced by hydroxyl radicals. Additionally in acute oral toxicity study, female rats were treated at 5000 mg/kg body weight of P. longifolia leaf extract and observed for signs of toxicity for 14 days. P. longifolia leaf extract did not produce any treatment-related toxic effects in rats.

  7. Mechanisms of free radical-induced damage to DNA.

    Science.gov (United States)

    Dizdaroglu, Miral; Jaruga, Pawel

    2012-04-01

    Endogenous and exogenous sources cause free radical-induced DNA damage in living organisms by a variety of mechanisms. The highly reactive hydroxyl radical reacts with the heterocyclic DNA bases and the sugar moiety near or at diffusion-controlled rates. Hydrated electron and H atom also add to the heterocyclic bases. These reactions lead to adduct radicals, further reactions of which yield numerous products. These include DNA base and sugar products, single- and double-strand breaks, 8,5'-cyclopurine-2'-deoxynucleosides, tandem lesions, clustered sites and DNA-protein cross-links. Reaction conditions and the presence or absence of oxygen profoundly affect the types and yields of the products. There is mounting evidence for an important role of free radical-induced DNA damage in the etiology of numerous diseases including cancer. Further understanding of mechanisms of free radical-induced DNA damage, and cellular repair and biological consequences of DNA damage products will be of outmost importance for disease prevention and treatment.

  8. Singlet oxygen-mediated damage to proteins and its consequences

    DEFF Research Database (Denmark)

    Davies, Michael Jonathan

    2003-01-01

    by the transfer of energy to ground state (triplet) molecular oxygen by either protein-bound, or other, chromophores. Singlet oxygen can also be generated by a range of other enzymatic and non-enzymatic reactions including processes mediated by heme proteins, lipoxygenases, and activated leukocytes, as well...... the absorption of UV radiation by the protein, or bound chromophore groups, thereby generating excited states (singlet or triplets) or radicals via photo-ionisation. The second major process involves indirect oxidation of the protein via the formation and subsequent reactions of singlet oxygen generated...... as radical termination reactions. This paper reviews the data available on singlet oxygen-mediated protein oxidation and concentrates primarily on the mechanisms by which this excited state species brings about changes to both the side-chains and backbone of amino acids, peptides, and proteins. Recent work...

  9. Repair of oxidative DNA damage by amino acids.

    Science.gov (United States)

    Milligan, J R; Aguilera, J A; Ly, A; Tran, N Q; Hoang, O; Ward, J F

    2003-11-01

    Guanyl radicals, the product of the removal of a single electron from guanine, are produced in DNA by the direct effect of ionizing radiation. We have produced guanyl radicals in DNA by using the single electron oxidizing agent (SCN)2-, itself derived from the indirect effect of ionizing radiation via thiocyanate scavenging of OH. We have examined the reactivity of guanyl radicals in plasmid DNA with the six most easily oxidized amino acids cysteine, cystine, histidine, methionine, tryptophan and tyrosine and also simple ester and amide derivatives of them. Cystine and histidine derivatives are unreactive. Cysteine, methionine, tyrosine and particularly tryptophan derivatives react to repair guanyl radicals in plasmid DNA with rate constants in the region of approximately 10(5), 10(5), 10(6) and 10(7) dm3 mol(-1) s(-1), respectively. The implication is that amino acid residues in DNA binding proteins such as histones might be able to repair by an electron transfer reaction the DNA damage produced by the direct effect of ionizing radiation or by other oxidative insults.

  10. Herpes simplex virus induces neural oxidative damage via microglial cell Toll-like receptor-2

    Directory of Open Access Journals (Sweden)

    Little Morgan R

    2010-06-01

    Full Text Available Abstract Background Using a murine model of herpes simplex virus (HSV-1 encephalitis, our laboratory has determined that induction of proinflammatory mediators in response to viral infection is largely mediated through a Toll-like receptor-2 (TLR2-dependent mechanism. Published studies have shown that, like other inflammatory mediators, reactive oxygen species (ROS are generated during viral brain infection. It is increasingly clear that ROS are responsible for facilitating secondary tissue damage during central nervous system infection and may contribute to neurotoxicity associated with herpes encephalitis. Methods Purified microglial cell and mixed neural cell cultures were prepared from C57B/6 and TLR2-/- mice. Intracellular ROS production in cultured murine microglia was measured via 2', 7'-Dichlorofluorescin diacetate (DCFH-DA oxidation. An assay for 8-isoprostane, a marker of lipid peroxidation, was utilized to measure free radical-associated cellular damage. Mixed neural cultures obtained from β-actin promoter-luciferase transgenic mice were used to detect neurotoxicity induced by HSV-infected microglia. Results Stimulation with HSV-1 elevated intracellular ROS in wild-type microglial cell cultures, while TLR2-/- microglia displayed delayed and attenuated ROS production following viral infection. HSV-infected TLR2-/- microglia produced less neuronal oxidative damage to mixed neural cell cultures in comparison to HSV-infected wild-type microglia. Further, HSV-infected TLR2-/- microglia were found to be less cytotoxic to cultured neurons compared to HSV-infected wild-type microglia. These effects were associated with decreased activation of p38 MAPK and p42/p44 ERK in TLR2-/- mice. Conclusions These studies demonstrate the importance of microglial cell TLR2 in inducing oxidative stress and neuronal damage in response to viral infection.

  11. Role of free radicals in radiation chemical aging

    Energy Technology Data Exchange (ETDEWEB)

    Greenstock, C L

    1986-01-01

    Ionizing radiation initiates chemical changes in DNA, phospholipid membranes and other critical cell targets, that, if allowed to accumulate unrepaired, may lead to aging and other chronic effects. The chemical effects are free radical mediated, the principal damaging species being radical OH and to a lesser extent O2-anion radical and the molecular product H/sub 2/O/sub 2/. Many compounds can act in combination with ionizing radiation, to amplify the potential oxidative stress. Chemicals, ultra-violet light, lipid peroxides and their breakdown products may increase the extent of acute and chronic radiobiological effects.

  12. Self-Terminating, Oxidative Radical Cyclizations

    Directory of Open Access Journals (Sweden)

    Uta Wille

    2004-05-01

    Full Text Available The recently discovered novel concept of self-terminating, oxidative radical cyclizations, through which alkynes can be converted into carbonyl compounds under very mild reaction conditions using O-centered inorganic and organic radicals as oxidants, is described

  13. Melatonin and Structurally-Related Compounds Protect Synaptosomal Membranes from Free Radical Damage

    Directory of Open Access Journals (Sweden)

    María A. Sáenz

    2010-01-01

    Full Text Available Since biological membranes are composed of lipids and proteins we tested the in vitro antioxidant properties of several indoleamines from the tryptophan metabolic pathway in the pineal gland against oxidative damage to lipids and proteins of synaptosomes isolated from the rat brain. Free radicals were generated by incubation with 0.1 mM FeCl3, and 0.1 mM ascorbic acid. Levels of malondialdehyde (MDA plus 4-hydroxyalkenal (4-HDA, and carbonyl content in the proteins were measured as indices of oxidative damage to lipids and proteins, respectively. Pinoline was the most powerful antioxidant evaluated, with melatonin, N-acetylserotonin, 5-hydroxytryptophan, 5-methoxytryptamine, 5-methoxytryptophol, and tryptoline also acting as antioxidants.

  14. Free radicals and antioxidants in primary fibromyalgia: an oxidative stress disorder?

    Science.gov (United States)

    Bagis, Selda; Tamer, Lulufer; Sahin, Gunsah; Bilgin, Ramazan; Guler, Hayal; Ercan, Bahadir; Erdogan, Canan

    2005-04-01

    The role of free radicals in fibromyalgia is controversial. In this study, 85 female patients with primary fibromyalgia and 80 age-, height-, and weight-matched healthy women were evaluated for oxidant/antioxidant balance. Malondialdehyde is a toxic metabolite of lipid peroxidation used as a marker of free radical damage. Superoxide dismutase is an intracellular antioxidant enzyme and shows antioxidant capacity. Pain was assessed by visual analog scale. Tender points were assessed by palpation. Age, smoking, body mass index (BMI), and duration of disease were also recorded. Malondialdehyde levels were significantly higher and superoxide dismutase levels significantly lower in fibromyalgic patients than controls. Age, BMI, smoking, and duration of disease did not affect these parameters. We found no correlation between pain and number of tender points. In conclusion, oxidant/antioxidant balances were changed in fibromyalgia. Increased free radical levels may be responsible for the development of fibromyalgia. These findings may support the hypothesis of fibromyalgia as an oxidative disorder.

  15. Hydroxyl radicals (·OH) are associated with titanium dioxide (TiO2) nanoparticle-induced cytotoxicity and oxidative DNA damage in fish cells

    International Nuclear Information System (INIS)

    Reeves, James F.; Davies, Simon J.; Dodd, Nicholas J.F.; Jha, Awadhesh N.

    2008-01-01

    TiO 2 nanoparticles ( 2 nanoparticles on goldfish skin cells (GFSk-S1), either alone or in combination with UVA. Whilst neutral red retention (NRR) assay (a measure of lysosomal membrane integrity) was used to evaluate cell viability, a modified Comet assay using bacterial lesion-specific repair endonucleases (Endo-III, Fpg) was employed to specifically target oxidative DNA damage. Additionally, electron spin resonance (ESR) studies with different spin traps were carried out for qualitative analysis of free radical generation. For cell viability, TiO 2 alone (0.1-1000 μg ml -1 ) had little effect whereas co-exposure with UVA (0.5-2.0 kJ m -2 ) caused a significant dose-dependent decrease which was dependent on both the concentration of TiO 2 and the dose of UVA administered. For the Comet assay, doses of 1, 10 and 100 μg ml -1 in the absence of UVA caused elevated levels of Fpg-sensitive sites, indicating the oxidation of purine DNA bases (i.e. guanine) by TiO 2 . UVA irradiation of TiO 2 -treated cells caused further increases in DNA damage. ESR studies revealed that the observed toxic effects of nanoparticulate TiO 2 were most likely due to hydroxyl radical (·OH) formation

  16. Inhibition of peroxynitrite-mediated DNA strand cleavage and hydroxyl radical formation by aspirin at pharmacologically relevant concentrations: Implications for cancer intervention

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Wei [Division of Biomedical Sciences, Edward Via Virginia College of Osteopathic Medicine, Virginia Tech Corporate Research Center, Blacksburg, VA 24060 (United States); College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310035 (China); Department of Food Science and Technology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 (United States); Zhu, Hong; Jia, Zhenquan [Division of Biomedical Sciences, Edward Via Virginia College of Osteopathic Medicine, Virginia Tech Corporate Research Center, Blacksburg, VA 24060 (United States); Li, Jianrong [College of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou 310035 (China); Misra, Hara P. [Division of Biomedical Sciences, Edward Via Virginia College of Osteopathic Medicine, Virginia Tech Corporate Research Center, Blacksburg, VA 24060 (United States); Zhou, Kequan, E-mail: kzhou@wayne.edu [Department of Nutrition and Food Science, Wayne State University, Detroit, MI 48202 (United States); Li, Yunbo, E-mail: yli@vcom.vt.edu [Division of Biomedical Sciences, Edward Via Virginia College of Osteopathic Medicine, Virginia Tech Corporate Research Center, Blacksburg, VA 24060 (United States)

    2009-12-04

    Epidemiological studies have suggested that the long-term use of aspirin is associated with a decreased incidence of human malignancies, especially colorectal cancer. Since accumulating evidence indicates that peroxynitrite is critically involved in multistage carcinogenesis, this study was undertaken to investigate the ability of aspirin to inhibit peroxynitrite-mediated DNA damage. Peroxynitrite and its generator 3-morpholinosydnonimine (SIN-1) were used to cause DNA strand breaks in {phi}X-174 plasmid DNA. We demonstrated that the presence of aspirin at concentrations (0.25-2 mM) compatible with amounts in plasma during chronic anti-inflammatory therapy resulted in a significant inhibition of DNA cleavage induced by both peroxynitrite and SIN-1. Moreover, the consumption of oxygen caused by 250 {mu}M SIN-1 was found to be decreased in the presence of aspirin, indicating that aspirin might affect the auto-oxidation of SIN-1. Furthermore, EPR spectroscopy using 5,5-dimethylpyrroline-N-oxide (DMPO) as a spin trap demonstrated the formation of DMPO-hydroxyl radical adduct (DMPO-OH) from authentic peroxynitrite, and that aspirin at 0.25-2 mM potently diminished the radical adduct formation in a concentration-dependent manner. Taken together, these results demonstrate for the first time that aspirin at pharmacologically relevant concentrations can inhibit peroxynitrite-mediated DNA strand breakage and hydroxyl radical formation. These results may have implications for cancer intervention by aspirin.

  17. Inhibition of peroxynitrite-mediated DNA strand cleavage and hydroxyl radical formation by aspirin at pharmacologically relevant concentrations: Implications for cancer intervention

    International Nuclear Information System (INIS)

    Chen, Wei; Zhu, Hong; Jia, Zhenquan; Li, Jianrong; Misra, Hara P.; Zhou, Kequan; Li, Yunbo

    2009-01-01

    Epidemiological studies have suggested that the long-term use of aspirin is associated with a decreased incidence of human malignancies, especially colorectal cancer. Since accumulating evidence indicates that peroxynitrite is critically involved in multistage carcinogenesis, this study was undertaken to investigate the ability of aspirin to inhibit peroxynitrite-mediated DNA damage. Peroxynitrite and its generator 3-morpholinosydnonimine (SIN-1) were used to cause DNA strand breaks in φX-174 plasmid DNA. We demonstrated that the presence of aspirin at concentrations (0.25-2 mM) compatible with amounts in plasma during chronic anti-inflammatory therapy resulted in a significant inhibition of DNA cleavage induced by both peroxynitrite and SIN-1. Moreover, the consumption of oxygen caused by 250 μM SIN-1 was found to be decreased in the presence of aspirin, indicating that aspirin might affect the auto-oxidation of SIN-1. Furthermore, EPR spectroscopy using 5,5-dimethylpyrroline-N-oxide (DMPO) as a spin trap demonstrated the formation of DMPO-hydroxyl radical adduct (DMPO-OH) from authentic peroxynitrite, and that aspirin at 0.25-2 mM potently diminished the radical adduct formation in a concentration-dependent manner. Taken together, these results demonstrate for the first time that aspirin at pharmacologically relevant concentrations can inhibit peroxynitrite-mediated DNA strand breakage and hydroxyl radical formation. These results may have implications for cancer intervention by aspirin.

  18. Protection of DPPC phospholipid liposomal membrane against radiation oxidative damage by antioxidants

    Energy Technology Data Exchange (ETDEWEB)

    Marathe, D.L.; Pandey, B.N.; Mishra, K.P [Bhabha Atomic Research Centre, Mumbai (India)

    2000-05-01

    Investigations in our laboratory on egg lecithin liposomes have recently showed a marked protection against damage by gamma radiation when cholesterol was present in the composition of vesicles suggesting a role of bilayer molecular architecture in the mechanism of free radical mediated lipid peroxidation. Present study was designed to determine the changes in bilayer permeability in DPPC unilamelar vesicles after exposure to gamma radiation by monitoring the leakage of pre-loaded carboxyfluorescein (CF), a marker loaded in aqueous interior of vesicle and fluidity alterations in the bilayer using fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH), a membrane bilayer probe. It was found that radiation doses of an order of magnitude higher were required to produce detectable changes in vesicles of DPPC than in the vesicles of egg lecithin suggesting a modulating role of chemical nature of composition in the membrane radiation sensitivity. It was significant to find that the leakage of CF from and incorporation of DPH into vesicle bilayer showed similar response pattern to radiation doses (0.1-6 kGy) which was also found to be dose rate dependent. Presence of antioxidants; alpha-tocopherol (0.15 mole %) in the bilayer membrane or ascorbic acid (0.1 mM) in the aqueous region significantly protected DPPC vesicles from radiation damage as determined from DPH uptake kinetics suggesting involvement of reactive free radicals of lipids as well as water radicals in the mechanism of membrane peroxidative damage. The magnitude of protection was found to increase with the increasing concentration of both these antioxidants but comparisons showed that {alpha}-tocopherol was far more effective in protecting the vesicles than ascorbic acid. These results contribute to our understanding of the mechanism of radiation oxidative damage and its modification by radical scavenging and/or organizational modulation which emphasize the importance of structure and composition of

  19. Protection of DPPC phospholipid liposomal membrane against radiation oxidative damage by antioxidants

    International Nuclear Information System (INIS)

    Marathe, D.L.; Pandey, B.N.; Mishra, K.P

    2000-01-01

    Investigations in our laboratory on egg lecithin liposomes have recently showed a marked protection against damage by gamma radiation when cholesterol was present in the composition of vesicles suggesting a role of bilayer molecular architecture in the mechanism of free radical mediated lipid peroxidation. Present study was designed to determine the changes in bilayer permeability in DPPC unilamelar vesicles after exposure to gamma radiation by monitoring the leakage of pre-loaded carboxyfluorescein (CF), a marker loaded in aqueous interior of vesicle and fluidity alterations in the bilayer using fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH), a membrane bilayer probe. It was found that radiation doses of an order of magnitude higher were required to produce detectable changes in vesicles of DPPC than in the vesicles of egg lecithin suggesting a modulating role of chemical nature of composition in the membrane radiation sensitivity. It was significant to find that the leakage of CF from and incorporation of DPH into vesicle bilayer showed similar response pattern to radiation doses (0.1-6 kGy) which was also found to be dose rate dependent. Presence of antioxidants; alpha-tocopherol (0.15 mole %) in the bilayer membrane or ascorbic acid (0.1 mM) in the aqueous region significantly protected DPPC vesicles from radiation damage as determined from DPH uptake kinetics suggesting involvement of reactive free radicals of lipids as well as water radicals in the mechanism of membrane peroxidative damage. The magnitude of protection was found to increase with the increasing concentration of both these antioxidants but comparisons showed that α-tocopherol was far more effective in protecting the vesicles than ascorbic acid. These results contribute to our understanding of the mechanism of radiation oxidative damage and its modification by radical scavenging and/or organizational modulation which emphasize the importance of structure and composition of

  20. Nitroxides are more efficient inhibitors of oxidative damage to calf skin collagen than antioxidant vitamins.

    Science.gov (United States)

    Venditti, Elisabetta; Scirè, Andrea; Tanfani, Fabio; Greci, Lucedio; Damiani, Elisabetta

    2008-01-01

    Reactive oxygen species generated upon UV-A exposure appear to play a major role in dermal connective tissue transformations including degradation of skin collagen. Here we investigate on oxidative damage to collagen achieved by exposure to (i) UV-A irradiation and to (ii) AAPH-derived radicals and on its possible prevention using synthetic and natural antioxidants. Oxidative damage was identified through SDS-PAGE, circular dichroism spectroscopy and quantification of protein carbonyl residues. Collagen (2 mg/ml) exposed to UV-A and to AAPH-derived radicals was degraded in a time- and dose-dependent manner. Upon UV-A exposure, maximum damage was observable at 730 kJ/m2 UV-A, found to be equivalent to roughly 2 h of sunshine, while exposure to 5 mM AAPH for 2 h at 50 degrees C lead to maximum collagen degradation. In both cases, dose-dependent protection was achieved by incubation with muM concentrations of nitroxide radicals, where the extent of protection was shown to be dictated by their structural differences whereas the vitamins E and C proved less efficient inhibitors of collagen damage. These results suggest that nitroxide radicals may be able to prevent oxidative injury to dermal tissues in vivo alternatively to commonly used natural antioxidants.

  1. Tobacco Smoke: Involvement of Reactive Oxygen Species and Stable Free Radicals in Mechanisms of Oxidative Damage, Carcinogenesis and Synergistic Effects with Other Respirable Particles

    Science.gov (United States)

    Valavanidis, Athanasios; Vlachogianni, Thomais; Fiotakis, Konstantinos

    2009-01-01

    Tobacco smoke contains many toxic, carcinogenic and mutagenic chemicals, as well as stable and unstable free radicals and reactive oxygen species (ROS) in the particulate and the gas phase with the potential for biological oxidative damage. Epidemiological evidence established that smoking is one of the most important extrinsic factor of premature morbidity and mortality. The objective of this study was to investigate oxidative and carcinogenic mechanisms of tobacco and synergistic action with other respirable particles in the respiratory system of smokers. Electron Paramagnetic Resonance (EPR) and spin-trapping techniques were used to study stable free radicals in the cigarette tar, and unstable superoxide anion (O2•−) and hydroxyl (HO•) radicals in the smoke Results showed that the semiquinone radical system has the potential for redox recycling and oxidative action. Further, results proved that aqueous cigarette tar (ACT) solutions can generate adducts with DNA nucleobases, particularly the mutagenic 8-hydroxy-2’-deoxyguanosine (a biomarker for carcinogenesis). Also, we observed synergistic effects in the generation of HO•, through the Fenton reaction, with environmental respirable particles (asbestos fibres, coal dust, etc.) and ambient particulate matter (PM), such as PM10, PM2.5 and diesel exhaust particles (DEP). The highest synergistic effects was observed with the asbestos fibres (freshly grounded), PM2.5 and DEP. Finally, we discuss results from our previous study of conventional cellulose acetate filters and “bio-filters” with hemoglobin impregnated activated carbon, which showed that these filters do not substantially alter the free radical content of smoke in the particulate and in the gaseous phase. PMID:19440393

  2. Tobacco Smoke: Involvement of Reactive Oxygen Species and Stable Free Radicals in Mechanisms of Oxidative Damage, Carcinogenesis and Synergistic Effects with Other Respirable Particles

    Directory of Open Access Journals (Sweden)

    Konstantinos Fiotakis

    2009-02-01

    Full Text Available Tobacco smoke contains many toxic, carcinogenic and mutagenic chemicals, as well as stable and unstable free radicals and reactive oxygen species (ROS in the particulate and the gas phase with the potential for biological oxidative damage. Epidemiological evidence established that smoking is one of the most important extrinsic factor of premature morbidity and mortality. The objective of this study was to investigate oxidative and carcinogenic mechanisms of tobacco and synergistic action with other respirable particles in the respiratory system of smokers. Electron Paramagnetic Resonance (EPR and spin- trapping techniques were used to study stable free radicals in the cigarette tar, and unstable superoxide anion (O2·- and hydroxyl (HO· radicals in the smoke Results showed that the semiquinone radical system has the potential for redox recycling and oxidative action. Further, results proved that aqueous cigarette tar (ACT solutions can generate adducts with DNA nucleobases, particularly the mutagenic 8-hydroxy-2’-deoxyguanosine (a biomarker for carcinogenesis.Also, we observed synergistic effects in the generation of HO·, through the Fenton reaction, with environmental respirable particles (asbestos fibres, coal dust, etc. and ambient particulate matter (PM, such as PM10, PM2.5 and diesel exhaust particles (DEP. The highest synergistic effects was observed with the asbestos fibres (freshly grounded, PM2.5 and DEP. Finally, we discuss results from our previous study of conventional cellulose acetate filters and “bio-filters” with hemoglobin impregnated activated carbon, which showed that these filters do not substantially alter the free radical content of smoke in the particulate and in the gaseous phase.

  3. Chemical determination of free radical-induced damage to DNA.

    Science.gov (United States)

    Dizdaroglu, M

    1991-01-01

    Free radical-induced damage to DNA in vivo can result in deleterious biological consequences such as the initiation and promotion of cancer. Chemical characterization and quantitation of such DNA damage is essential for an understanding of its biological consequences and cellular repair. Methodologies incorporating the technique of gas chromatography/mass spectrometry (GC/MS) have been developed in recent years for measurement of free radical-induced DNA damage. The use of GC/MS with selected-ion monitoring (SIM) facilitates unequivocal identification and quantitation of a large number of products of all four DNA bases produced in DNA by reactions with hydroxyl radical, hydrated electron, and H atom. Hydroxyl radical-induced DNA-protein cross-links in mammalian chromatin, and products of the sugar moiety in DNA are also unequivocally identified and quantitated. The sensitivity and selectivity of the GC/MS-SIM technique enables the measurement of DNA base products even in isolated mammalian chromatin without the necessity of first isolating DNA, and despite the presence of histones. Recent results reviewed in this article demonstrate the usefulness of the GC/MS technique for chemical determination of free radical-induced DNA damage in DNA as well as in mammalian chromatin under a vast variety of conditions of free radical production.

  4. Oxidative stress induced damage in benign and malignant breast diseases: histopathological and biochemical aspects

    Directory of Open Access Journals (Sweden)

    Seema Khanna

    2012-04-01

    Full Text Available Increasing evidences indicate involvement of free radicals in the pathogenesis of benign and malignant breast diseases. Free radicals are highly reactive molecules and react with non–radicals in chain reaction leading to formation of new free radicals. If the defense mechanism of body fails to combat them, these free radicals pose a threat of injuring tissues by reacting with cell lipids. Lipids in the cell membrane undergo degradation to form hydroperoxides, which decompose to form a variety of products including malondialdehyde (MDA. MDA therefore was used as a marker to assess oxidative damage of cells and tissues. The aim of the present study was to assess the status of oxidative stress in the patients of benign and malignant breast diseases. Study has been made on the blood samples of 25 cases of benign breast disease and on an equal number of breast carcinoma patients. 20 healthy subjects were taken as the control cases.Mean MDA levels were significantly raised with depletion of antioxidant activity in all the patients in comparison to their control group suggesting the role of oxidative damage in the aetiopathogenesis of disease.

  5. Ex-vivo and in vitro protective effects of kolaviron against oxygen-derived radical-induced DNA damage and oxidative stress in human lymphocytes and rat liver cells

    DEFF Research Database (Denmark)

    Farombi, E.O.; Moller, P.; Dragsted, L.O.

    2004-01-01

    at concentrations between 30-90 mumol/L and decreased H2O2-induced DNA strand breaks and oxidized bases. Neither alpha-tocopherol nor curcumin decreased H2O2-induced DNA damage in this assay. In lymphocytes incubated with Fe3+ /GSH, Fe3+ was reduced to Fe2+ by GSH initiating a free radical generating reaction which...

  6. Fingerprinting DNA oxidation processes: IR characterization of the 5-methyl-2'-deoxycytidine radical cation.

    Science.gov (United States)

    Bucher, Dominik B; Pilles, Bert M; Pfaffeneder, Toni; Carell, Thomas; Zinth, Wolfgang

    2014-02-24

    Methylated cytidine plays an important role as an epigenetic signal in gene regulation. Its oxidation products are assumed to be involved in active demethylation processes but also in damaging DNA. Here, we report the photochemical production of the 5-methyl-2'-deoxycytidine radical cation via a two-photon ionization process. The radical cation is detected by time-resolved IR spectroscopy and identified by band assignment using density functional theory calculations. Two final oxidation products are characterized with liquid chromatography coupled to mass spectrometry. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Antioxidant-mediated up-regulation of OGG1 via NRF2 induction is associated with inhibition of oxidative DNA damage in estrogen-induced breast cancer

    International Nuclear Information System (INIS)

    Singh, Bhupendra; Chatterjee, Anwesha; Ronghe, Amruta M; Bhat, Nimee K; Bhat, Hari K

    2013-01-01

    Estrogen metabolism-mediated oxidative stress is suggested to play an important role in estrogen-induced breast carcinogenesis. We have earlier demonstrated that antioxidants, vitamin C (Vit C) and butylated hydroxyanisole (BHA) inhibit 17β-estradiol (E2)-mediated oxidative stress and oxidative DNA damage, and breast carcinogenesis in female August Copenhagen Irish (ACI) rats. The objective of the present study was to characterize the mechanism by which above antioxidants prevent DNA damage during breast carcinogenesis. Female ACI rats were treated with E2; Vit C; Vit C + E2; BHA; and BHA + E2 for up to 240 days. mRNA and protein levels of a DNA repair enzyme 8-Oxoguanine DNA glycosylase (OGG1) and a transcription factor NRF2 were quantified in the mammary and mammary tumor tissues of rats after treatment with E2 and compared with that of rats treated with antioxidants either alone or in combination with E2. The expression of OGG1 was suppressed in mammary tissues and in mammary tumors of rats treated with E2. Expression of NRF2 was also significantly suppressed in E2-treated mammary tissues and in mammary tumors. Vitamin C or BHA treatment prevented E2-mediated decrease in OGG1 and NRF2 levels in the mammary tissues. Chromatin immunoprecipitation analysis confirmed that antioxidant-mediated induction of OGG1 was through increased direct binding of NRF2 to the promoter region of OGG1. Studies using silencer RNA confirmed the role of OGG1 in inhibition of oxidative DNA damage. Our studies suggest that antioxidants Vit C and BHA provide protection against oxidative DNA damage and E2-induced mammary carcinogenesis, at least in part, through NRF2-mediated induction of OGG1

  8. Peroxynitrite-mediated oxidation of plasma fibronectin

    DEFF Research Database (Denmark)

    Degendorfer, Georg; Chuang, Christine Y; Kawasaki, Hiroaki

    2016-01-01

    Fibronectin is a large dimeric glycoprotein present in both human plasma and in basement membranes. The latter are specialized extracellular matrices underlying endothelial cells in the artery wall. Peroxynitrous acid (ONOOH) a potent oxidizing and nitrating agent, is formed in vivo from superoxide...... and nitric oxide radicals by stimulated macrophages and other cells. Considerable evidence supports ONOOH involvement in human atherosclerotic lesion development and rupture, possibly via extracellular matrix damage. Here we demonstrate that Tyr and Trp residues on human plasma fibronectin are highly...

  9. Hydroxyl Radical-Mediated Novel Modification of Peptides: N-Terminal Cyclization through the Formation of α-Ketoamide.

    Science.gov (United States)

    Lee, Seon Hwa; Kyung, Hyunsook; Yokota, Ryo; Goto, Takaaki; Oe, Tomoyuki

    2015-01-20

    The hydroxyl radical-mediated oxidation of peptides and proteins constitutes a large group of post-translational modifications that can result in structural and functional changes. These oxidations can lead to hydroxylation, sulfoxidation, or carbonylation of certain amino acid residues and cleavage of peptide bonds. In addition, hydroxyl radicals can convert the N-terminus of peptides to an α-ketoamide via abstraction of the N-terminal α-hydrogen and hydrolysis of the ketimine intermediate. In the present study, we identified N-terminal cyclization as a novel modification mediated by a hydroxyl radical. The reaction of angiotensin (Ang) II (DRVYIHPF) and the hydroxyl radical generated by the Cu(II)/ascorbic acid (AA) system or UV/hydrogen peroxide system produced N-terminal cyclized-Ang II (Ang C) and pyruvamide-Ang II (Ang P, CH3COCONH-RVYIHPF). The structure of Ang C was confirmed by mass spectrometry and comparison to an authentic standard. The subsequent incubation of isolated Ang P in the presence of Cu(II)/AA revealed that Ang P was the direct precursor of Ang C. The proposed mechanism involves the formation of a nitrogen-centered (aminyl) radical, which cyclizes to form a five-membered ring containing the alkoxy radical. The subsequent β-scission reaction of the alkoxyl radical results in the cleavage of the terminal CH3CO group. The initial aminyl radical can be stabilized by chelation to the Cu(II) ions. The affinity of Ang C toward the Ang II type 1 receptor was significantly lower than that of Ang II or Ang P. Ang C was not further metabolized by aminopeptidase A, which converts Ang II to Ang III. Hydroxyl radical-mediated N-terminal cyclization was also observed in other Ang peptides containing N-terminal alanine, arginine, valine, and amyloid β 1-11 (DAEFRHDSGYE).

  10. Radioprotective effects of Asparagus racemosus extracts against free radical damage in rat liver mitochondria

    International Nuclear Information System (INIS)

    Boloor, K.K.; Kamat, J.P.; Devasagayam, T.P.A.; Venkatachalam, S.R.

    2000-01-01

    The possible antioxidant effect of the extracts of Asparagus racemosus against membrane damage induced by free radicals generated during γ-radiation was examined in rat liver/brain mitochondria. These extracts displayed significant antioxidant properties in mitochondria against oxidation of both lipids and proteins as assessed by lipid peroxidation, protein oxidation and depletion of thiols. The inhibitory effect of the extracts, rich in polysaccharides like galactose, was more than that of the established antioxidants glutathione and ascorbic acid. (author)

  11. Cytoprotective Mechanisms Mediated by Polyphenols from Chilean Native Berries against Free Radical-Induced Damage on AGS Cells.

    Science.gov (United States)

    Ávila, Felipe; Theoduloz, Cristina; López-Alarcón, Camilo; Dorta, Eva; Schmeda-Hirschmann, Guillermo

    2017-01-01

    The prevalence of cytoprotective mechanisms induced by polyphenols such as activation of intracellular antioxidant responses (ICM) and direct free radical scavenging was investigated in native Chilean species of strawberries, raspberries, and currants. Human gastric epithelial cells were co- and preincubated with polyphenolic-enriched extracts (PEEs) from Chilean raspberries ( Rubus geoides ), strawberries ( Fragaria chiloensis ssp. chiloensis f . chiloensis ), and currants ( Ribes magellanicum ) and challenged with peroxyl and hydroxyl radicals. Cellular protection was determined in terms of cell viability, glyoxalase I and glutathione s-transferases activities, and carboxymethyl lysine (CML) and malondialdehyde levels. Our results indicate that cytoprotection induced by ICM was the prevalent mechanism for Rubus geoides and F. chiloensis . This agreed with increased levels of glyoxalase I and glutathione S-transferase activities in cells preincubated with PEEs. ORAC index indicated that F. chiloensis was the most efficient peroxyl radical scavenger. Moreover, ICM mediated by F. chiloensis was effective in protecting cells from CML accumulation in contrast to the protective effects induced by free radical scavenging. Our results indicate that although both polyphenol-mediated mechanisms can exert protective effects, ICM was the most prevalent in AGS cells. These results suggest a potential use of these native berries as functional food.

  12. 3-Hydroxylysine, a potential marker for studying radical-induced protein oxidation

    DEFF Research Database (Denmark)

    Morin, B; Bubb, W A; Davies, Michael Jonathan

    1998-01-01

    albumin (BSA) and human low-density lipoprotein (LDL)] and diseased human tissues (atherosclerotic plaques and lens cataractous proteins). This work was aimed at investigating oxidized lysine as a sensitive marker for protein oxidation, as such residues are present on protein surfaces, and are therefore...... likely to be particularly susceptible to oxidation by radicals in bulk solution. HO* attack on lysine in the presence of oxygen, followed by NaBH4 reduction, is shown to give rise to (2S)-3-hydroxylysine [(2S)-2,6-diamino-3-hydroxyhexanoic acid], (2S)-4-hydroxylysine [(2S)-2,6-diamino-4-hydroxyhexanoic...... acid], (2S, 5R)-5-hydroxylysine [(2S,5R)-2,6-diamino-5-hydroxyhexanoic acid], and (2S,5S)-5-hydroxylysine [(2S,5S)-2,6-diamino-5-hydroxyhexanoic acid]. 5-Hydroxylysines are natural products formed by lysyl oxidase and are therefore not good markers of radical-mediated oxidation. The other...

  13. Cytoprotective effect of phloroglucinol on oxidative stress induced cell damage via catalase activation.

    Science.gov (United States)

    Kang, Kyoung Ah; Lee, Kyoung Hwa; Chae, Sungwook; Zhang, Rui; Jung, Myung Sun; Ham, Young Min; Baik, Jong Seok; Lee, Nam Ho; Hyun, Jin Won

    2006-02-15

    We investigated the cytoprotective effect of phloroglucinol, which was isolated from Ecklonia cava (brown alga), against oxidative stress induced cell damage in Chinese hamster lung fibroblast (V79-4) cells. Phloroglucinol was found to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, hydrogen peroxide (H(2)O(2)), hydroxy radical, intracellular reactive oxygen species (ROS), and thus prevented lipid peroxidation. As a result, phloroglucinol reduced H(2)O(2) induced apoptotic cells formation in V79-4 cells. In addition, phloroglucinol inhibited cell damage induced by serum starvation and radiation through scavenging ROS. Phloroglucinol increased the catalase activity and its protein expression. In addition, catalase inhibitor abolished the protective effect of phloroglucinol from H(2)O(2) induced cell damage. Furthermore, phloroglucinol increased phosphorylation of extracellular signal regulated kinase (ERK). Taken together, the results suggest that phloroglucinol protects V79-4 cells against oxidative damage by enhancing the cellular catalase activity and modulating ERK signal pathway. (c) 2005 Wiley-Liss, Inc.

  14. Iron-Mediated Lysosomal Membrane Permeabilization in Ethanol-Induced Hepatic Oxidative Damage and Apoptosis: Protective Effects of Quercetin

    Directory of Open Access Journals (Sweden)

    Yanyan Li

    2016-01-01

    Full Text Available Iron, in its free ferrous states, can catalyze Fenton reaction to produce OH∙, which is recognized as a crucial role in the pathogenesis of alcoholic liver diseases (ALD. As a result of continuous decomposition of iron-containing compounds, lysosomes contain a pool of redox-active iron. To investigate the important role of intralysosomal iron in alcoholic liver injury and the potential protection of quercetin, male C57BL/6J mice fed by Lieber De Carli diets containing ethanol (30% of total calories were cotreated by quercetin or deferoxamine (DFO for 15 weeks and ethanol-incubated mice primary hepatocytes were pretreated with FeCl3, DFO, and bafilomycin A1 at their optimal concentrations and exposure times. Chronic ethanol consumption caused an evident increase in lysosomal redox-active iron accompanying sustained oxidative damage. Iron-mediated ROS could trigger lysosomal membrane permeabilization (LMP and subsequent mitochondria apoptosis. The hepatotoxicity was attenuated by reducing lysosomal iron while being exacerbated by escalating lysosomal iron. Quercetin substantially alleviated the alcoholic liver oxidative damage and apoptosis by decreasing lysosome iron and ameliorating iron-mediated LMP, which provided a new prospective of the use of quercetin against ALD.

  15. Free radicals, oxidative stress and importance of antioxidants in human health

    Directory of Open Access Journals (Sweden)

    K.I. Priyadarsini

    2011-07-01

    Full Text Available Reactive oxygen species (ROS is a collective term used for oxygen containing free radicals, depending on their reactivity and oxidizing ability. ROS participate in a variety of chemical reactions with biomolecules leading to a pathological condition known as oxidative stress. Antioxidants are employed to protect biomolecules from the damaging effects of such ROS. In the beginning, antioxidant research was mainly aimed at understanding free radical reactions of ROS with antioxidants employing biochemical assays and kinetic methods. Later on, studies began to be directed to monitor the ability of anti-oxidants to modulate cellular signaling proteins like receptors, secondary messengers, transcription factors, etc. Of late several studies have indicated that antioxidants can also have deleterious effects on human health depending on dosage and bio-availability. It is therefore, necessary to validate the utility of antioxidants in improvement of human health in order to take full advantage of their therapeutic potential.

  16. Cytoprotective Mechanisms Mediated by Polyphenols from Chilean Native Berries against Free Radical-Induced Damage on AGS Cells

    Directory of Open Access Journals (Sweden)

    Felipe Ávila

    2017-01-01

    Full Text Available The prevalence of cytoprotective mechanisms induced by polyphenols such as activation of intracellular antioxidant responses (ICM and direct free radical scavenging was investigated in native Chilean species of strawberries, raspberries, and currants. Human gastric epithelial cells were co- and preincubated with polyphenolic-enriched extracts (PEEs from Chilean raspberries (Rubus geoides, strawberries (Fragaria chiloensis ssp. chiloensis f. chiloensis, and currants (Ribes magellanicum and challenged with peroxyl and hydroxyl radicals. Cellular protection was determined in terms of cell viability, glyoxalase I and glutathione s-transferases activities, and carboxymethyl lysine (CML and malondialdehyde levels. Our results indicate that cytoprotection induced by ICM was the prevalent mechanism for Rubus geoides and F. chiloensis. This agreed with increased levels of glyoxalase I and glutathione S-transferase activities in cells preincubated with PEEs. ORAC index indicated that F. chiloensis was the most efficient peroxyl radical scavenger. Moreover, ICM mediated by F. chiloensis was effective in protecting cells from CML accumulation in contrast to the protective effects induced by free radical scavenging. Our results indicate that although both polyphenol-mediated mechanisms can exert protective effects, ICM was the most prevalent in AGS cells. These results suggest a potential use of these native berries as functional food.

  17. Free radicals quenching potential, protective properties against oxidative mediated ion toxicity and HPLC phenolic profile of a Cameroonian spice: Piper guineensis.

    Science.gov (United States)

    Moukette Moukette, Bruno; Constant Anatole, Pieme; Nya Biapa, Cabral Prosper; Njimou, Jacques Romain; Ngogang, Jeanne Yonkeu

    2015-01-01

    Considerations on antioxidants derived from plants have continuously increased during this decade because of their beneficial effects on human health. In the present study we investigated the free radical scavenging properties of extracts from Piper guineense ( P. guineense ) and their inhibitory potentials against oxidative mediated ion toxicity. The free radical quenching properties of the extracts against [1,1-diphenyl-2-picrylhydrazyl (DPPH•), 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS•), hydroxyl radical (HO•), nitric oxide (NO•)] radical and their antioxidant potentials by FRAP and phosphomolybdenum were determined as well as their protective properties on liver enzymes. The phenolic profile was also investigated by HPLC. The results obtained, revealed that the extracts significantly inhibited the DPPH, NO, HO and ABTS radicals in a concentration depending manner. They also showed a significant ferrous ion chelating ability through FRAP and phosphomolybdenum antioxidant potential. Their polyphenol contents varied depending on the type of extracts and the solvent used. The hydroethanolic extracts (FFH) and the ethanolic extracts (FFE) of P. guineense leaves showed the higher level of phenolic compounds respectively of 21.62 ± 0.06 mg caffeic acid/g dried extract (CAE/g DE) and 19.01 ± 0.03 CAE/g DE. The HPLC phenolic compounds profile revealed a higher quantity of Eugenol, quercetin, rutin and catechin in the stem than in the leaves. The presence of these molecules could be responsible of the protective potentials of P. guineense extracts against lipid peroxidation and SOD, catalase and peroxidase. In conclusion, P. guineense extracts demonstrated significant antioxidant property and may be used as a prospective protector against metal related toxicity.

  18. Ceruloplasmin (ferroxidase) oxidizes hydroxylamine probes: deceptive implications for free radical detection.

    Science.gov (United States)

    Ganini, Douglas; Canistro, Donatella; Jiang, JinJie; Jang, JinJie; Stadler, Krisztian; Mason, Ronald P; Kadiiska, Maria B

    2012-10-01

    Ceruloplasmin (ferroxidase) is a copper-binding protein known to promote Fe(2+) oxidation in plasma of mammals. In addition to its classical ferroxidase activity, ceruloplasmin is known to catalyze the oxidation of various substrates, such as amines and catechols. Assays based on cyclic hydroxylamine oxidation are used to quantify and detect free radicals in biological samples ex vivo and in vitro. We show here that human ceruloplasmin promotes the oxidation of the cyclic hydroxylamine 1-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine hydrochloride (CPH) and related probes in Chelex-treated phosphate buffer and rat serum. The reaction is suppressed by the metal chelators DTPA, EDTA, and desferal, whereas heparin and bathocuproine have no effect. Catalase or superoxide dismutase additions do not interfere with the CPH-oxidation yield, demonstrating that oxygen-derived free radicals are not involved in the CPH oxidation mediated by ceruloplasmin. Plasma samples immunodepleted of ceruloplasmin have lower levels of CPH oxidation, which confirms the role of ceruloplasmin (ferroxidase) as a biological oxidizing agent of cyclic hydroxylamines. In conclusion, we show that the ferroxidase activity of ceruloplasmin is a possible biological source of artifacts in the cyclic hydroxylamine-oxidation assay used for reactive oxygen species detection and quantification. Published by Elsevier Inc.

  19. DNA Binding Hydroxyl Radical Probes.

    Science.gov (United States)

    Tang, Vicky J; Konigsfeld, Katie M; Aguilera, Joe A; Milligan, Jamie R

    2012-01-01

    The hydroxyl radical is the primary mediator of DNA damage by the indirect effect of ionizing radiation. It is a powerful oxidizing agent produced by the radiolysis of water and is responsible for a significant fraction of the DNA damage associated with ionizing radiation. There is therefore an interest in the development of sensitive assays for its detection. The hydroxylation of aromatic groups to produce fluorescent products has been used for this purpose. We have examined four different chromophores which produce fluorescent products when hydroxylated. Of these, the coumarin system suffers from the fewest disadvantages. We have therefore examined its behavior when linked to a cationic peptide ligand designed to bind strongly to DNA.

  20. Thyroid hormone-induced oxidative damage on lipids, glutathione and DNA in the mouse heart.

    Science.gov (United States)

    Gredilla, R; Barja, G; López-Torres, M

    2001-10-01

    Oxygen radicals of mitochondrial origin are involved in oxidative damage. In order to analyze the possible relationship between metabolic rate, oxidative stress and oxidative damage, OF1 female mice were rendered hyper- and hypothyroid by chronic administration of 0.0012% L-thyroxine (T4) and 0.05% 6-n-propyl-2-thiouracil (PTU), respectively, in their drinking water for 5 weeks. Hyperthyroidism significantly increased the sensitivity to lipid peroxidation in the heart, although the endogenous levels of lipid peroxidation were not altered. Thyroid hormone-induced oxidative stress also resulted in higher levels of GSSG and GSSG/GSH ratio. Oxidative damage to mitochondrial DNA was greater than that to genomic DNA. Hyperthyroidism decreased oxidative damage to genomic DNA. Hypothyroidism did not modify oxidative damage in the lipid fraction but significantly decreased GSSG and GSSG/GSH ratio and oxidative damage to mitochondrial DNA. These results indicate that thyroid hormones modulate oxidative damage to lipids and DNA, and cellular redox potential in the mouse heart. A higher oxidative stress in the hyperthyroid group is presumably neutralized in the case of nuclear DNA by an increase in repair activity, thus protecting this key molecule. Treatment with PTU, a thyroid hormone inhibitor, reduced oxidative damage in the different cell compartments.

  1. Examining food additives and spices for their anti-oxidant ability to counteract oxidative damage due to chronic exposure to free radicals from environmental pollutants

    Science.gov (United States)

    Martinez, Raul A., III

    The main objective of this work was to examine food additives and spices (from the Apiaceae family) to determine their antioxidant properties to counteract oxidative stress (damage) caused by Environmental pollutants. Environmental pollutants generate Reactive Oxygen species and Reactive Nitrogen species. Star anise essential oil showed lower antioxidant activity than extracts using DPPH scavenging. Dill Seed -- Anethum Graveolens -the monoterpene components of dill showed to activate the enzyme glutathione-S-transferase , which helped attach the antioxidant molecule glutathione to oxidized molecules that would otherwise do damage in the body. The antioxidant activity of extracts of dill was comparable with ascorbic acid, alpha-tocopherol, and quercetin in in-vitro systems. Black Cumin -- Nigella Sativa: was evaluated the method 1,1-diphenyl2-picrylhhydrazyl (DPPH) radical scavenging activity. Positive correlations were found between the total phenolic content in the black cumin extracts and their antioxidant activities. Caraway -- Carum Carvi: The antioxidant activity was evaluated by the scavenging effects of 1,1'-diphenyl-2-picrylhydrazyl (DPPH). Caraway showed strong antioxidant activity. Cumin -- Cuminum Cyminum - the major polyphenolic were extracted and separated by HPTLC. The antioxidant activity of the cumin extract was tested on 1,1'-diphenyl-2- picrylhydrazyl (DPPH) free radical scavenging. Coriander -- Coriandrum Sativum - the antioxidant and free-radical-scavenging property of the seeds was studied and also investigated whether the administration of seeds curtails oxidative stress. Coriander seed powder not only inhibited the process of Peroxidative damage, but also significantly reactivated the antioxidant enzymes and antioxidant levels. The seeds also showed scavenging activity against superoxides and hydroxyl radicals. The total polyphenolic content of the seeds was found to be 12.2 galic acid equivalents (GAE)/g while the total flavonoid content

  2. Spin trapping combined with quantitative mass spectrometry defines free radical redistribution within the oxidized hemoglobin:haptoglobin complex.

    Science.gov (United States)

    Vallelian, Florence; Garcia-Rubio, Ines; Puglia, Michele; Kahraman, Abdullah; Deuel, Jeremy W; Engelsberger, Wolfgang R; Mason, Ronald P; Buehler, Paul W; Schaer, Dominik J

    2015-08-01

    Extracellular or free hemoglobin (Hb) accumulates during hemolysis, tissue damage, and inflammation. Heme-triggered oxidative reactions can lead to diverse structural modifications of lipids and proteins, which contribute to the propagation of tissue damage. One important target of Hb׳s peroxidase reactivity is its own globin structure. Amino acid oxidation and crosslinking events destabilize the protein and ultimately cause accumulation of proinflammatory and cytotoxic Hb degradation products. The Hb scavenger haptoglobin (Hp) attenuates oxidation-induced Hb degradation. In this study we show that in the presence of hydrogen peroxide (H2O2), Hb and the Hb:Hp complex share comparable peroxidative reactivity and free radical generation. While oxidation of both free Hb and Hb:Hp complex generates a common tyrosine-based free radical, the spin-trapping reaction with 5,5-dimethyl-1-pyrroline N-oxide (DMPO) yields dissimilar paramagnetic products in Hb and Hb:Hp, suggesting that radicals are differently redistributed within the complex before reacting with the spin trap. With LC-MS(2) mass spectrometry we assigned multiple known and novel DMPO adduct sites. Quantification of these adducts suggested that the Hb:Hp complex formation causes extensive delocalization of accessible free radicals with drastic reduction of the major tryptophan and cysteine modifications in the β-globin chain of the Hb:Hp complex, including decreased βCys93 DMPO adduction. In contrast, the quantitative changes in DMPO adduct formation on Hb:Hp complex formation were less pronounced in the Hb α-globin chain. In contrast to earlier speculations, we found no evidence that free Hb radicals are delocalized to the Hp chain of the complex. The observation that Hb:Hp complex formation alters free radical distribution in Hb may help to better understand the structural basis for Hp as an antioxidant protein. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Induction of oxidative DNA damage by mesalamine in the presence of copper: A potential mechanism for mesalamine anticancer activity

    International Nuclear Information System (INIS)

    Zimmerman, Ryan P.; Jia, Zhenquan; Zhu, Hong; Vandjelovic, Nathan; Misra, Hara P.; Wang, Jianmin; Li, Yunbo

    2011-01-01

    Mesalamine is the first line pharmacologic intervention for patients with ulcerative colitis, and recent epidemiologic studies have demonstrated a protective association between therapeutic use of the drug and colorectal carcinoma. However, the mechanism by which this protection is afforded has yet to be elucidated. Because copper is found at higher than normal concentrations in neoplastic cell nuclei and is known to interact with phenolic compounds to generate reactive oxygen species, we investigated whether the reaction of mesalamine/copper was able to induce oxidative DNA strand breaks in φX-174 RF I plasmid DNA, and the various components of the mechanism by which the reaction occurred. Plasmid DNA strand breaks were induced by pharmacologically relevant concentrations of mesalamine in the presence of a micromolar concentration of Cu(II), and damage was inhibited by bathocuproinedisulfonic acid (BCS) and catalase. Further, we showed that the reaction of copper with mesalamine consumed molecular oxygen, which was inhibited by BCS. Electron paramagnetic resonance spectral analysis of the reaction of copper/mesalamine indicated the presence of the hydroxyl radical, which was inhibited by both BCS and catalase. This study demonstrates for the first time that through a copper-redox cycling mechanism, the copper-mediated oxidation of mesalamine is a pro-oxidant interaction that generates hydroxyl radicals which may participate in oxidative DNA damage. These results demonstrate a potential mechanism of the anticancer effects of mesalamine in patients with ulcerative colitis.

  4. Nitroxide-Mediated Radical Polymerization of Styrene Initiated from the Surface of Titanium Oxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    M. Abbasian

    2016-01-01

    Full Text Available Titanium dioxide (TiO2 nanoparticles, with an average size of about 45 nm, were encapsulated by polystyrene using in situ nitroxide mediated radical polymerization   in the presence of 3-aminopropyl triethoxy silane (APTES as a coupling agent and 2, 2, 6, 6-tetramethylpiperidinyl-1-oxy  as a initiator. First, the initiator for NMRP was covalently bonded onto the surface of Titanium dioxide nanoparticles through our novel method. For this purpose, the surface of TiO2 nanoparticle was treated with 3-aminopropyl triethoxy silane, a silane coupling agent, and then these functionalized nanoparticles was reacted with ±-chloro phenyl acetyl chloride. The chlorine groups were converted to nitroxide mediated groups by coupling with 1-hydroxy-2, 2, 6, 6-tetramethyl piperidine. These modified TiO2 nanoparticles were then dispersed in styrene (St monomers to carry out the in situ free radical polymerization.

  5. Peroxiredoxin 1 Protects Telomeres from Oxidative Damage and Preserves Telomeric DNA for Extension by Telomerase

    Directory of Open Access Journals (Sweden)

    Eric Aeby

    2016-12-01

    Full Text Available Oxidative damage of telomeres can promote cancer, cardiac failure, and muscular dystrophy. Specific mechanisms protecting telomeres from oxidative damage have not been described. We analyzed telomeric chromatin composition during the cell cycle and show that the antioxidant enzyme peroxiredoxin 1 (PRDX1 is enriched at telomeres during S phase. Deletion of the PRDX1 gene leads to damage of telomeric DNA upon oxidative stress, revealing a protective function of PRDX1 against oxidative damage at telomeres. We also show that the oxidized nucleotide 8-oxo-2′deoxyguanosine-5′-triphosphate (8oxodGTP causes premature chain termination when incorporated by telomerase and that some DNA substrates terminating in 8oxoG prevent extension by telomerase. Thus, PRDX1 safeguards telomeres from oxygen radicals to counteract telomere damage and preserve telomeric DNA for elongation by telomerase.

  6. Renal damage mediated by oxidative stress: a hypothesis of protective effects of red wine.

    Science.gov (United States)

    Rodrigo, Ramón; Rivera, Gonzalo

    2002-08-01

    Over the last decade, oxidative stress has been implicated in the pathogenesis of a wide variety of seemingly unrelated renal diseases. Epidemiological studies have documented an association of moderate wine consumption with a decreased risk of cardiovascular and neurological diseases; however, similar studies in the kidney are still lacking. The kidney is an organ highly vulnerable to damage caused by reactive oxygen species (ROS), likely due to the abundance of polyunsaturated fatty acids in the composition of renal lipids. ROS are involved in the pathogenic mechanism of conditions such as glomerulosclerosis and tubulointerstitial fibrosis. The health benefits of moderate consumption of red wine can be partly attributed to its antioxidant properties. Indeed, the kidney antioxidant defense system is enhanced after chronic exposure to moderate amounts of wine, a response arising from the combined effects of ethanol and the nonalcoholic components, mainly polyphenols. Polyphenols behave as potent ROS scavengers and metal chelators; ethanol, in turn, modulates the activity of antioxidant enzymes. Therefore, a hypothesis that red wine causes a decreased vulnerability of the kidney to the oxidative challenges could be proposed. This view is partly supported by direct evidences indicating that wine and antioxidants isolated from red wine, as well as other antioxidants, significantly attenuate or prevent the oxidative damage to the kidney. The present hypothesis paper provides a collective body of evidence suggesting a protective role of moderate wine consumption against the production and progression of renal diseases, based on the existing concepts on the pathophysiology of kidney injury mediated by oxidative stress.

  7. Free radicals and lipid peroxidation mediated injury in burn trauma: the role of antioxidant therapy

    International Nuclear Information System (INIS)

    Horton, Jureta W.

    2003-01-01

    Burn trauma produces significant fluid shifts that, in turn, reduce cardiac output and tissue perfusion. Treatment approaches to major burn injury include administration of crystalloid solutions to correct hypovolemia and to restore peripheral perfusion. While this aggressive postburn volume replacement increases oxygen delivery to previously ischemic tissue, this restoration of oxygen delivery is thought to initiate a series of deleterious events that exacerbate ischemia-related tissue injury. While persistent hypoperfusion after burn trauma would produce cell death, volume resuscitation may exacerbate the tissue injury that occurred during low flow state. It is clear that after burn trauma, tissue adenosine triphosphate (ATP) levels gradually fall, and increased adenosine monophosphate (AMP) is converted to hypoxanthine, providing substrate for xanthine oxidase. These complicated reactions produce hydrogen peroxide and superoxide, clearly recognized deleterious free radicals. In addition to xanthine oxidase related free radical generation in burn trauma, adherent-activated neutrophils produce additional free radicals. Enhanced free radical production is paralleled by impaired antioxidant mechanisms; as indicated by burn-related decreases in superoxide dismutase, catalase, glutathione, alpha tocopherol, and ascorbic acid levels. Burn related upregulation of inducible nitric oxide synthase (iNOS) may produce peripheral vasodilatation, upregulate the transcription factor nuclear factor kappa B (NF-κB), and promote transcription and translation of numerous inflammatory cytokines. NO may also interact with the superoxide radical to yield peroxynitrite, a highly reactive mediator of tissue injury. Free radical mediated cell injury has been supported by postburn increases in systemic and tissue levels of lipid peroxidation products such as conjugated dienes, thiobarbituric acid reaction products, or malondialdehyde (MDA) levels. Antioxidant therapy in burn therapy

  8. Oxidative stress and nerve damage: Role in chemotherapy induced peripheral neuropathy

    Directory of Open Access Journals (Sweden)

    Aparna Areti

    2014-01-01

    Full Text Available Peripheral neuropathy is a severe dose limiting toxicity associated with cancer chemotherapy. Ever since it was identified, the clear pathological mechanisms underlying chemotherapy induced peripheral neuropathy (CIPN remain sparse and considerable involvement of oxidative stress and neuroinflammation has been realized recently. Despite the empirical use of antioxidants in the therapy of CIPN, the oxidative stress mediated neuronal damage in peripheral neuropathy is still debatable. The current review focuses on nerve damage due to oxidative stress and mitochondrial dysfunction as key pathogenic mechanisms involved in CIPN. Oxidative stress as a central mediator of apoptosis, neuroinflammation, metabolic disturbances and bioenergetic failure in neurons has been highlighted in this review along with a summary of research on dietary antioxidants and other nutraceuticals which have undergone prospective controlled clinical trials in patients undergoing chemotherapy.

  9. Organ-Protective Effects of Red Wine Extract, Resveratrol, in Oxidative Stress-Mediated Reperfusion Injury

    Directory of Open Access Journals (Sweden)

    Fu-Chao Liu

    2015-01-01

    Full Text Available Resveratrol, a polyphenol extracted from red wine, possesses potential antioxidative and anti-inflammatory effects, including the reduction of free radicals and proinflammatory mediators overproduction, the alteration of the expression of adhesion molecules, and the inhibition of neutrophil function. A growing body of evidence indicates that resveratrol plays an important role in reducing organ damage following ischemia- and hemorrhage-induced reperfusion injury. Such protective phenomenon is reported to be implicated in decreasing the formation and reaction of reactive oxygen species and pro-nflammatory cytokines, as well as the mediation of a variety of intracellular signaling pathways, including the nitric oxide synthase, nicotinamide adenine dinucleotide phosphate oxidase, deacetylase sirtuin 1, mitogen-activated protein kinase, peroxisome proliferator-activated receptor-gamma coactivator 1 alpha, hemeoxygenase-1, and estrogen receptor-related pathways. Reperfusion injury is a complex pathophysiological process that involves multiple factors and pathways. The resveratrol is an effective reactive oxygen species scavenger that exhibits an antioxidative property. In this review, the organ-protective effects of resveratrol in oxidative stress-related reperfusion injury will be discussed.

  10. Differential modification of oxic and anoxic radiation damage by chemicals. I. Simulation of the action of caffeine by certain inorganic radical scavengers

    International Nuclear Information System (INIS)

    Kesavan, P.C.; Sharma, G.J.; Afzal, S.M.J.

    1978-01-01

    Caffeine affords partial radioprotection against oxic damage, but potentiates anoxic damage in dry as well as presoaked barley seeds. Since our earlier studies have implicated a physicochemical pathway of action for such differential modification by caffeine, the effect of inorganic substances, known to scavenge specific categories of free radicals, on the oxic and anoxic components of radiation damage was investigated. It is found that the radiation-induced oxic damage is significantly reduced by potassium permanganate, potassium iodide, potassium nitrate, and potassium ferrocyanide which scavenge predominantly .H + e - /sub aq/, .OH, e - /sub aq/, and .OH radicals, respectively. Each of these four substances, like caffeine, also potentiates anoxic damage in dry seeds, but the anoxic damage in presoaked seeds is potentiated only by potassium ferrocyanide. These results do not confirm the view in the literature that the anoxic sensitization is largely mediated by .OH radicals. A discussion of these observations and the validity of comparing our seed data with those derived from experiments with bacterial spores and ''naked'' DNA solutions is presented

  11. Mechanistic Insights into Radical-Mediated Oxidation of Tryptophan from ab Initio Quantum Chemistry Calculations and QM/MM Molecular Dynamics Simulations.

    Science.gov (United States)

    Wood, Geoffrey P F; Sreedhara, Alavattam; Moore, Jamie M; Wang, John; Trout, Bernhardt L

    2016-05-12

    An assessment of the mechanisms of (•)OH and (•)OOH radical-mediated oxidation of tryptophan was performed using density functional theory calculations and ab initio plane-wave Quantum Mechanics/Molecular Mechanics (QM/MM) molecular dynamics simulations. For the (•)OH reactions, addition to the pyrrole ring at position 2 is the most favored site with a barrierless reaction in the gas phase. The subsequent degradation of this adduct through a H atom transfer to water was intermittently observed in aqueous-phase molecular dynamics simulations. For the (•)OOH reactions, addition to the pyrrole ring at position 2 is the most favored pathway, in contrast to the situation in the model system ethylene, where concerted addition to the double bond is preferred. From the (•)OOH position 2 adduct QM/MM simulations show that formation of oxy-3-indolanaline occurs readily in an aqueous environment. The observed transformation starts from an initial rupture of the O-O bond followed by a H atom transfer with the accompanying loss of an (•)OH radical to solution. Finally, classical molecular dynamics simulations were performed to equate observed differential oxidation rates of various tryptophan residues in monoclonal antibody fragments. It was found that simple parameters derived from simulation correlate well with the experimental data.

  12. Free radical mediated formation of 3-monochloropropanediol (3-MCPD) fatty acid diesters.

    Science.gov (United States)

    Zhang, Xiaowei; Gao, Boyan; Qin, Fang; Shi, Haiming; Jiang, Yuangrong; Xu, Xuebing; Yu, Liangli Lucy

    2013-03-13

    The present study was conducted to test the hypothesis that a free radical was formed and mediated the formation of 3-monochloropropanediol (3-MCPD) fatty acid diesters, a group of food contaminants, from diacylglycerols at high temperature under a low-moisture condition for the first time. The presence of free radicals in a vegetable oil kept at 120 °C for 20 min was demonstrated using an electron spin resonance (ESR) spectroscopy examination with 5,5-dimethylpyrroline-N-oxide (DMPO) as the spin trap agent. ESR investigation also showed an association between thermal treatment degree and the concentration of free radicals. A Fourier transform infrared spectroscopy (FT-IR) analysis of sn-1,2-stearoylglycerol (DSG) at 25 and 120 °C suggested the possible involvement of an ester carbonyl group in forming 3-MCPD diesters. On the basis of these results, a novel free radical mediated chemical mechanism was proposed for 3-MCPD diester formation. Furthermore, a quadrupole-time of flight (Q-TOF) MS/MS investigation was performed and detected the DMPO adducts with the cyclic acyloxonium free radical (CAFR) and its product MS ions, proving the presence of CAFR. Furthermore, the free radical mechanism was validated by the formation of 3-MCPD diesters through reacting DSG with a number of organic and inorganic chlorine sources including chlorine gas at 120 and 240 °C. The findings of this study might lead to the improvement of oil and food processing conditions to reduce the level of 3-MCPD diesters in foods and enhance food safety.

  13. Eleusine indica L. possesses antioxidant activity and precludes carbon tetrachloride (CCl₄)-mediated oxidative hepatic damage in rats.

    Science.gov (United States)

    Iqbal, Mohammad; Gnanaraj, Charles

    2012-07-01

    The purpose of this study was to evaluate the ability of aqueous extract of Eleusine indica to protect against carbon tetrachloride (CCl₄)-induced hepatic injury in rats. The antioxidant activity of E. indica was evaluated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay. The total phenolic content of E. indica was also determined. Biochemical parameters [e.g. alanine aminotransferase (ALT), aspartate aminotransferase (AST), malondialdehyde (MDA), glutathione (GSH), catalase, glutathione peroxidase, glutathione reductase, glutathione S-transferase and quinone reductase] were used to evaluate hepatic damage in animals pretreated with E. indica and intoxicated with CCl₄. CCl₄-mediated hepatic damage was also evaluated by histopathologically. E. indica extract was able to reduce the stable DPPH level in a dose-dependent manner. The half maximal inhibitory concentration (IC₅₀) value was 2350 μg/ml. Total phenolic content was found to be 14.9 ± 0.002 mg/g total phenolic expressed as gallic acid equivalent per gram of extract. Groups pretreated with E. indica showed significantly increased activity of antioxidant enzymes compared to the CCl₄-intoxicated group (p indica pretreatment (p indica-pretreated groups as compared to the CCl₄-intoxicated group. The protective effect of E. indica was further evident through decreased histopathological alterations in the liver. The results of our study indicate that the hepatoprotective effects of E. indica might be ascribable to its antioxidant and free radical scavenging property.

  14. Histone H1- and other protein- and amino acid-hydroperoxides can give rise to free radicals which oxidize DNA

    DEFF Research Database (Denmark)

    Luxford, C; Morin, B; Dean, R T

    1999-01-01

    analysis has demonstrated that radicals from histone H1-hydroperoxides, and other protein and amino acid hydroperoxides, can also oxidize both free 2'-deoxyguanosine and intact calf thymus DNA to give the mutagenic oxidized base 7, 8-dihydro-8-oxo-2'-deoxyguanosine (8-hydroxy-2'-deoxyguanosine, 8-oxod......Exposure of amino acids, peptides and proteins to radicals, in the presence of oxygen, gives high yields of hydroperoxides. These materials are readily decomposed by transition metal ions to give further radicals. We hypothesized that hydroperoxide formation on nuclear proteins, and subsequent...... decomposition of these hydroperoxides to radicals, might result in oxidative damage to associated DNA. We demonstrate here that exposure of histone H1 and model compounds to gamma-radiation in the presence of oxygen gives hydroperoxides in a dose-dependent manner. These hydroperoxides decompose to oxygen...

  15. Grape (Vitis vinifera) extracts protect against radiation-induced oxidative stress and DNA damage

    International Nuclear Information System (INIS)

    Singha, Indrani; Das, Subir Kumar; Saxena, S.; Gautam, S.

    2016-01-01

    Ionizing radiation (IR) causes oxidative stress through the overwhelming generation of reactive oxygen species (ROS) in the living cells leading further to the oxidative damage to biomolecules. Grapes (Vitis vinifera) contain several bioactive phytochemicals and are the richest source of antioxidant. In this study, we investigated and compared in vitro antioxidant activity and DNA damage protective property of the grape extracts of four different cultivars, including the Thompson seedless, Flame seedless, Kishmish chorni and Red globe. The activities of ascorbic acid oxidase and catalase significantly (p<0.01) differed among extracts within the same cultivar, while that of peroxidase and polyphenol oxidase did not differ significantly among extracts of any cultivar. In vitro antioxidant activities were assessed by ferric-reducing antioxidant power (FRAP) assay and ABTS. The superoxide radical-scavenging activity was higher in the seed as compared to the skin or pulp of the same cultivar. DNA damage was evaluated in acellular system using pBR322 plasmid relaxation. Grape extract was able to effectively scavenge free radicals in vitro. It could significantly prevent radiation-induced DNA damage. Furthermore, the protective action of grape depends on the source of extract and type of the cultivars. (author)

  16. Epigenetic oxidative redox shift (EORS) theory of aging unifies the free radical and insulin signaling theories

    OpenAIRE

    Brewer, Gregory J.

    2009-01-01

    Harman’s free radical theory of aging posits that oxidized macromolecules accumulate with age to decrease function and shorten life-span. However, nutritional and genetic interventions to boost antioxidants have generally failed to increase life-span. Furthermore, the free radical theory fails to explain why exercise causes higher levels of oxyradical damage, but generally promotes healthy aging. The separate anti-aging paradigms of genetic or caloric reductions in the insulin signaling pathw...

  17. Hydroxyl radicals ({center_dot}OH) are associated with titanium dioxide (TiO{sub 2}) nanoparticle-induced cytotoxicity and oxidative DNA damage in fish cells

    Energy Technology Data Exchange (ETDEWEB)

    Reeves, James F.; Davies, Simon J.; Dodd, Nicholas J.F. [School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Jha, Awadhesh N. [School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom)], E-mail: a.jha@plymouth.ac.uk

    2008-04-02

    TiO{sub 2} nanoparticles (<100 nm diameter) have been reported to cause oxidative stress related effects, including inflammation, cytotoxicity and genomic instability, either alone or in the presence of UVA irradiation in mammalian studies. Despite the fact that the aquatic environment is often the ultimate recipient of all contaminants there is a paucity of data pertaining to the potential detrimental effects of nanoparticles on aquatic organisms. Therefore, these investigations aimed to evaluate the potential cytotoxic and genotoxic effects of TiO{sub 2} nanoparticles on goldfish skin cells (GFSk-S1), either alone or in combination with UVA. Whilst neutral red retention (NRR) assay (a measure of lysosomal membrane integrity) was used to evaluate cell viability, a modified Comet assay using bacterial lesion-specific repair endonucleases (Endo-III, Fpg) was employed to specifically target oxidative DNA damage. Additionally, electron spin resonance (ESR) studies with different spin traps were carried out for qualitative analysis of free radical generation. For cell viability, TiO{sub 2} alone (0.1-1000 {mu}g ml{sup -1}) had little effect whereas co-exposure with UVA (0.5-2.0 kJ m{sup -2}) caused a significant dose-dependent decrease which was dependent on both the concentration of TiO{sub 2} and the dose of UVA administered. For the Comet assay, doses of 1, 10 and 100 {mu}g ml{sup -1} in the absence of UVA caused elevated levels of Fpg-sensitive sites, indicating the oxidation of purine DNA bases (i.e. guanine) by TiO{sub 2}. UVA irradiation of TiO{sub 2}-treated cells caused further increases in DNA damage. ESR studies revealed that the observed toxic effects of nanoparticulate TiO{sub 2} were most likely due to hydroxyl radical ({center_dot}OH) formation.

  18. 4β-Hydroxywithanolide E selectively induces oxidative DNA damage for selective killing of oral cancer cells.

    Science.gov (United States)

    Tang, Jen-Yang; Huang, Hurng-Wern; Wang, Hui-Ru; Chan, Ya-Ching; Haung, Jo-Wen; Shu, Chih-Wen; Wu, Yang-Chang; Chang, Hsueh-Wei

    2018-03-01

    Reactive oxygen species (ROS) induction had been previously reported in 4β-hydroxywithanolide (4βHWE)-induced selective killing of oral cancer cells, but the mechanism involving ROS and the DNA damage effect remain unclear. This study explores the role of ROS and oxidative DNA damage of 4βHWE in the selective killing of oral cancer cells. Changes in cell viability, morphology, ROS, DNA double strand break (DSB) signaling (γH2AX foci in immunofluorescence and DSB signaling in western blotting), and oxidative DNA damage (8-oxo-2'deoxyguanosine [8-oxodG]) were detected in 4βHWE-treated oral cancer (Ca9-22) and/or normal (HGF-1) cells. 4βHWE decreased cell viability, changed cell morphology and induced ROS generation in oral cancer cells rather than oral normal cells, which were recovered by a free radical scavenger N-acetylcysteine (NAC). For immunofluorescence, 4βHWE also accumulated more of the DSB marker, γH2AX foci, in oral cancer cells than in oral normal cells. For western blotting, DSB signaling proteins such as γH2AX and MRN complex (MRE11, RAD50, and NBS1) were overexpressed in 4βHWE-treated oral cancer cells in different concentrations and treatment time. In the formamidopyrimidine-DNA glycolyase (Fpg)-based comet assay and 8-oxodG-based flow cytometry, the 8-oxodG expressions were higher in 4βHWE-treated oral cancer cells than in oral normal cells. All the 4βHWE-induced DSB and oxidative DNA damage to oral cancer cells were recovered by NAC pretreatment. Taken together, the 4βHWE selectively induced DSB and oxidative DNA damage for the ROS-mediated selective killing of oral cancer cells. © 2017 Wiley Periodicals, Inc.

  19. Environmentally persistent free radicals amplify ultrafine particle mediated cellular oxidative stress and cytotoxicity

    Directory of Open Access Journals (Sweden)

    Balakrishna Shrilatha

    2009-04-01

    Full Text Available Abstract Background Combustion generated particulate matter is deposited in the respiratory tract and pose a hazard to the lungs through their potential to cause oxidative stress and inflammation. We have previously shown that combustion of fuels and chlorinated hydrocarbons produce semiquinone-type radicals that are stabilized on particle surfaces (i.e. environmentally persistent free radicals; EPFRs. Because the composition and properties of actual combustion-generated particles are complex, heterogeneous in origin, and vary from day-to-day, we have chosen to use surrogate particle systems. In particular, we have chosen to use the radical of 2-monochlorophenol (MCP230 as the EPFR because we have previously shown that it forms a EPFR on Cu(IIO surfaces and catalyzes formation of PCDD/F. To understand the physicochemical properties responsible for the adverse pulmonary effects of combustion by-products, we have exposed human bronchial epithelial cells (BEAS-2B to MCP230 or the CuO/silica substrate. Our general hypothesis was that the EPFR-containing particle would have greater toxicity than the substrate species. Results Exposure of BEAS-2B cells to our combustion generated particle systems significantly increased reactive oxygen species (ROS generation and decreased cellular antioxidants resulting in cell death. Resveratrol treatment reversed the decline in cellular glutathione (GSH, glutathione peroxidase (GPx, and superoxide dismutase (SOD levels for both types of combustion-generated particle systems. Conclusion The enhanced cytotoxicity upon exposure to MCP230 correlated with its ability to generate more cellular oxidative stress and concurrently reduce the antioxidant defenses of the epithelial cells (i.e. reduced GSH, SOD activity, and GPx. The EPFRs in MCP230 also seem to be of greater biological concern due to their ability to induce lipid peroxidation. These results are consistent with the oxidizing nature of the CuO/silica ultrafine

  20. Endogenous melatonin and oxidatively damaged guanine in DNA

    Directory of Open Access Journals (Sweden)

    Poulsen Henrik E

    2009-10-01

    Full Text Available Abstract Background A significant body of literature indicates that melatonin, a hormone primarily produced nocturnally by the pineal gland, is an important scavenger of hydroxyl radicals and other reactive oxygen species. Melatonin may also lower the rate of DNA base damage resulting from hydroxyl radical attack and increase the rate of repair of that damage. This paper reports the results of a study relating the level of overnight melatonin production to the overnight excretion of the two primary urinary metabolites of the repair of oxidatively damaged guanine in DNA. Methods Mother-father-daughter(s families (n = 55 were recruited and provided complete overnight urine samples. Total overnight creatinine-adjusted 6-sulphatoxymelatonin (aMT6s/Cr has been shown to be highly correlated with total overnight melatonin production. Urinary 8-oxo-7,8-dihydro-guanine (8-oxoGua results from the repair of DNA or RNA guanine via the nucleobase excision repair pathway, while urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG may possibly result from the repair of DNA guanine via the nucleotide excision repair pathway. Total overnight urinary levels of 8-oxodG and 8-oxoGua are therefore a measure of total overnight guanine DNA damage. 8-oxodG and 8-oxoGua were measured using a high-performance liquid chromatography-electrospray ionization tandem mass spectrometry assay. The mother, father, and oldest sampled daughter were used for these analyses. Comparisons between the mothers, fathers, and daughters were calculated for aMT6s/Cr, 8-oxodG, and 8-oxoGua. Regression analyses of 8-oxodG and 8-oxoGua on aMT6s/Cr were conducted for mothers, fathers, and daughters separately, adjusting for age and BMI (or weight. Results Among the mothers, age range 42-80, lower melatonin production (as measured by aMT6s/CR was associated with significantly higher levels of 8-oxodG (p Conclusion Low levels of endogenous melatonin production among older individuals may lead to

  1. Radiation-initiated free-radical fragmentation of biologically active glycerides

    International Nuclear Information System (INIS)

    Akhrem, A.A.; Kisel', M.A.; Shadyro, O.I.; Yurkova, I.L.

    1993-01-01

    Oxidation reactions of the free-radical type play a decisive role in the initial processes of radiation damage. The most suitable substrates for such reactions are lipids. Lipids are a basic structural element of biomembranes and are involved in the barrier function and biocatalytic activity of such membranes. Free-radical degradation of membrane lipids can lead to serious damage and ultimately to destruction of the living cell. A well-studied type of free-radical conversion of lipids is oxidation of polyunsaturated fatty acid residues, so-called peroxide oxidation of lipids. In this paper, using as examples dimyristoylphosphatidyl glycerol (DMPG), monoglycerides, and glycerophosphate, the authors investigated the possibility of free-radical degradation in compounds of a lipid nature containing the α,β-bifunctional group

  2. Radiation-induced damage in E. coli B: The effect of superoxide radicals and molecular oxygen. Progress report, December 1, 1978--November 30, 1979

    International Nuclear Information System (INIS)

    Samuni, A.; Czapski, G.

    The roles of superoxide radicals and of molecular oxygen in the radiodamage of E. coli B suspended in dilute phosphate buffer were studied. The presence of high concentrations of polyethylene glycol in the γ-irradiated cell suspensions, had no effect on bacterial radiosensitivity. This indicates that the damage was primarily endogenous, i.e. originated intracellularly. Saturation of the cell suspensions with N 2 O doubled the radiosensitivity, thus indicating that OH radicals are responsible for the majority of the damage (indirect radiation effect). The presence of oxygen either in the absence or presence of N 2 O brought about roughly a three-fold increase in the radiosensitivity. Since in the presence of N 2 O all e - /sub aq/ are scavenged by the nitrous oxide rather than by oxygen, this shows that superoxide radicals play no role in the bacterial radiodamage. Our results substantiate the attribution of the oxygen effect to a direct interaction of O 2 with the hydroxyl-radical-damaged sites on vital biomolecules, and exclude any significant contribution of e - /sub aq/ and superoxide radicals to the cellular radiodamage

  3. Measuring sunscreen protection against solar-simulated radiation-induced structural radical damage to skin using ESR/spin trapping: development of an ex vivo test method.

    Science.gov (United States)

    Haywood, Rachel; Volkov, Arsen; Andrady, Carima; Sayer, Robert

    2012-03-01

    The in vitro star system used for sunscreen UVA-testing is not an absolute measure of skin protection being a ratio of the total integrated UVA/UVB absorption. The in vivo persistent-pigment-darkening method requires human volunteers. We investigated the use of the ESR-detectable DMPO protein radical-adduct in solar-simulator-irradiated skin substitutes for sunscreen testing. Sunscreens SPF rated 20+ with UVA protection, reduced this adduct by 40-65% when applied at 2 mg/cm(2). SPF 15 Organic UVA-UVB (BMDBM-OMC) and TiO(2)-UVB filters and a novel UVA-TiO(2) filter reduced it by 21, 31 and 70% respectively. Conventional broad-spectrum sunscreens do not fully protect against protein radical-damage in skin due to possible visible-light contributions to damage or UVA-filter degradation. Anisotropic spectra of DMPO-trapped oxygen-centred radicals, proposed intermediates of lipid-oxidation, were detected in irradiated sunscreen and DMPO. Sunscreen protection might be improved by the consideration of visible-light protection and the design of filters to minimise radical leakage and lipid-oxidation.

  4. Critical role of NADPH oxidase in neuronal oxidative damage and microglia activation following traumatic brain injury.

    Directory of Open Access Journals (Sweden)

    Quan-Guang Zhang

    Full Text Available BACKGROUND: Oxidative stress is known to play an important role in the pathology of traumatic brain injury. Mitochondria are thought to be the major source of the damaging reactive oxygen species (ROS following TBI. However, recent work has revealed that the membrane, via the enzyme NADPH oxidase can also generate the superoxide radical (O(2(-, and thereby potentially contribute to the oxidative stress following TBI. The current study thus addressed the potential role of NADPH oxidase in TBI. METHODOLOGY/PRINCIPAL FINDINGS: The results revealed that NADPH oxidase activity in the cerebral cortex and hippocampal CA1 region increases rapidly following controlled cortical impact in male mice, with an early peak at 1 h, followed by a secondary peak from 24-96 h after TBI. In situ localization using oxidized hydroethidine and the neuronal marker, NeuN, revealed that the O(2(- induction occurred in neurons at 1 h after TBI. Pre- or post-treatment with the NADPH oxidase inhibitor, apocynin markedly inhibited microglial activation and oxidative stress damage. Apocynin also attenuated TBI-induction of the Alzheimer's disease proteins β-amyloid and amyloid precursor protein. Finally, both pre- and post-treatment of apocynin was also shown to induce significant neuroprotection against TBI. In addition, a NOX2-specific inhibitor, gp91ds-tat was also shown to exert neuroprotection against TBI. CONCLUSIONS/SIGNIFICANCE: As a whole, the study demonstrates that NADPH oxidase activity and superoxide production exhibit a biphasic elevation in the hippocampus and cortex following TBI, which contributes significantly to the pathology of TBI via mediation of oxidative stress damage, microglial activation, and AD protein induction in the brain following TBI.

  5. The basic chemistry of exercise-induced DNA oxidation: oxidative damage, redox signalling and their interplay

    Directory of Open Access Journals (Sweden)

    James Nathan Cobley

    2015-06-01

    Full Text Available Acute exercise increases reactive oxygen and nitrogen species generation. This phenomenon is associated with two major outcomes: (1 redox signalling and (2 macromolecule damage. Mechanistic knowledge of how exercise-induced redox signalling and macromolecule damage are interlinked is limited. This review focuses on the interplay between exercise-induced redox signalling and DNA damage, using hydroxyl radical (·OH and hydrogen peroxide (H2O2 as exemplars. It is postulated that the biological fate of H2O2 links the two processes and thus represents a bifurcation point between redox signalling and damage. Indeed, H2O2 can participate in two electron signalling reactions but its diffusion and chemical properties permit DNA oxidation following reaction with transition metals and ·OH generation. It is also considered that the sensing of DNA oxidation by repair proteins constitutes a non-canonical redox signalling mechanism. Further layers of interaction are provided by the redox regulation of DNA repair proteins and their capacity to modulate intracellular H2O2 levels. Overall, exercise-induced redox signalling and DNA damage may be interlinked to a greater extent than was previously thought but this requires further investigation.

  6. Insight into the Reaction Mechanism of Graphene Oxide with Oxidative Free Radical

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xuejiao; XU Liangyou

    2017-01-01

    Graphene oxide(GO),as an important derivative of graphene,could be considered as a super aromatic molecule decorated with a range of reactive oxygen-containing groups on its surface,which endows graphene high reactivity with other molecules.In our previous work,we demonstrated that GO sheets were cut into small pieces(graphene quantum dots,GQDs) by oxidative free radicals(hydroxyl radical HO or oxygen radical [O]) under UV irradiation.It is notable that reactions involving free radicals are influenced by reaction conditions pronouncedly.However,researches on details about reactions of GO with free radicals have not been reported thus far.In this work,the effects of different factors on the photo-Fenton reaction of GO were studied.It is demonstrated that the reaction rate is closely related to the concentration of free radicals.It is speculated that through the optimization of reaction conditions,the reaction of graphene with free radicals could carry out efficiently for further applications.

  7. Radiation damage to human erythrocytes. Relative contribution of hydroxyl and chloride radicals in N2O-saturated buffers

    International Nuclear Information System (INIS)

    Krokosz, Anita; Komorowska, Magdalena A.; Szweda-Lewandowska, Zofia

    2008-01-01

    The erythrocyte suspensions in Na-phosphate buffered isotonic NaCl solution (PBS) or Na-phosphate isotonic buffer (PB) (hematocrit 1%) were irradiated with the dose of 400 Gy under N 2 O. Erythrocytes were incubated in the medium in which the cells were irradiated or in fresh PBS. The level of damage to cells was estimated on the basis of the course of post-radiation hemolysis and hemoglobin (Hb) oxidation. The medium in which the cells were irradiated and incubated influenced the course of the post-radiation hemolysis and Hb oxidation as well as some other parameters. We discussed the contribution of hydroxyl and chloride radicals in the initiation of erythrocyte damage and oxygen modification of these processes

  8. Oxidative damage and aging: spotlight on mitochondria.

    Science.gov (United States)

    Linford, Nancy J; Schriner, Samuel E; Rabinovitch, Peter S

    2006-03-01

    Whereas free radical damage has been proposed as a key component in the tissue degeneration associated with aging, there has been little evidence that free radical damage limits life span in mammals. The current research shows that overexpression of the antioxidant enzyme catalase in mitochondria can extend mouse life span. These results highlight the importance of mitochondrial damage in aging and suggest that when targeted appropriately, boosting antioxidant defenses can increase mammalian life span.

  9. UVA activation of N-dialkylnitrosamines releasing nitric oxide, producing strand breaks as well as oxidative damages in DNA, and inducing mutations in the Ames test

    International Nuclear Information System (INIS)

    Arimoto-Kobayashi, Sakae; Sano, Kayoko; Machida, Masaki; Kaji, Keiko; Yakushi, Keiko

    2010-01-01

    We investigated the photo-mutagenicity and photo-genotoxicity of N-dialkylnitrosamines and its mechanisms of UVA activation. With simultaneous irradiation of UVA, photo-mutagenicity of seven N-dialkylnitrosamines was observed in Ames bacteria (Salmonella typhimurium TA1535) in the absence of metabolic activation. Mutagenicity of pre-irradiated N-dialkylnitrosamines was also observed with S. typhimurium hisG46, TA100, TA102 and YG7108 in the absence of metabolic activation. UVA-mediated mutation with N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) decreased by adding either the NO or OH radical scavenger. When superhelical DNA was irradiated with N-dialkylnitrosamines, nicked circular DNA appeared. Ten N-dialkylnitrosamines examined produced strand breaks in the treated DNA in the presence of UVA. The level of single-strand breaks in φX174 DNA mediated by N-nitrosomorpholine (NMOR) and UVA decreased by adding either a radical scavenger or superoxide dismutase. When calf thymus DNA was treated with N-dialkylnitrosamines (NDMA, NDEA, NMOR, N-nitrosopyrrolidine (NPYR) and N-nitrosopiperidine (NPIP)) and UVA, the ratio of 8-oxodG/dG in the DNA increased. Action spectra were obtained to determine if nitrosamine acts as a sensitizer of UVA. Both mutation frequency and NO formation were highest at the absorption maximum of nitrosamines, approximately 340 nm. The plots of NO formation and mutation frequency align with the absorption curve of NPYR, NMOR and NDMA. A significant linear correlation between the optical density of N-dialkynitrosamines at 340 nm and NO formation in each irradiated solution was revealed by ANOVA. We would like to propose the hypothesis that the N-nitroso moiety of N-dialkylnitrosamines absorbs UVA photons, UVA-photolysis of N-dialkylnitrosamines brings release of nitric oxide, and subsequent production of alkyl radical cations and active oxygen species follow as secondary events, which cause DNA strand breaks, oxidative and

  10. UVA activation of N-dialkylnitrosamines releasing nitric oxide, producing strand breaks as well as oxidative damages in DNA, and inducing mutations in the Ames test

    Energy Technology Data Exchange (ETDEWEB)

    Arimoto-Kobayashi, Sakae [Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima, Okayama 700-8530 (Japan); Sano, Kayoko; Machida, Masaki; Kaji, Keiko; Yakushi, Keiko [Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima, Okayama 700-8530 (Japan)

    2010-09-10

    We investigated the photo-mutagenicity and photo-genotoxicity of N-dialkylnitrosamines and its mechanisms of UVA activation. With simultaneous irradiation of UVA, photo-mutagenicity of seven N-dialkylnitrosamines was observed in Ames bacteria (Salmonella typhimurium TA1535) in the absence of metabolic activation. Mutagenicity of pre-irradiated N-dialkylnitrosamines was also observed with S. typhimurium hisG46, TA100, TA102 and YG7108 in the absence of metabolic activation. UVA-mediated mutation with N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) decreased by adding either the NO or OH radical scavenger. When superhelical DNA was irradiated with N-dialkylnitrosamines, nicked circular DNA appeared. Ten N-dialkylnitrosamines examined produced strand breaks in the treated DNA in the presence of UVA. The level of single-strand breaks in {phi}X174 DNA mediated by N-nitrosomorpholine (NMOR) and UVA decreased by adding either a radical scavenger or superoxide dismutase. When calf thymus DNA was treated with N-dialkylnitrosamines (NDMA, NDEA, NMOR, N-nitrosopyrrolidine (NPYR) and N-nitrosopiperidine (NPIP)) and UVA, the ratio of 8-oxodG/dG in the DNA increased. Action spectra were obtained to determine if nitrosamine acts as a sensitizer of UVA. Both mutation frequency and NO formation were highest at the absorption maximum of nitrosamines, approximately 340 nm. The plots of NO formation and mutation frequency align with the absorption curve of NPYR, NMOR and NDMA. A significant linear correlation between the optical density of N-dialkynitrosamines at 340 nm and NO formation in each irradiated solution was revealed by ANOVA. We would like to propose the hypothesis that the N-nitroso moiety of N-dialkylnitrosamines absorbs UVA photons, UVA-photolysis of N-dialkylnitrosamines brings release of nitric oxide, and subsequent production of alkyl radical cations and active oxygen species follow as secondary events, which cause DNA strand breaks, oxidative and

  11. Towards a "free radical theory of graying": melanocyte apoptosis in the aging human hair follicle is an indicator of oxidative stress induced tissue damage.

    Science.gov (United States)

    Arck, Petra Clara; Overall, Rupert; Spatz, Katharina; Liezman, Christiane; Handjiski, Bori; Klapp, Burghard F; Birch-Machin, Mark A; Peters, Eva Milena Johanne

    2006-07-01

    Oxidative stress is generated by a multitude of environmental and endogenous challenges such as radiation, inflammation, or psychoemotional stress. It also speeds the aging process. Graying is a prominent but little understood feature of aging. Intriguingly, the continuous melanin synthesis in the growing (anagen) hair follicle generates high oxidative stress. We therefore hypothesize that hair bulb melanocytes are especially susceptible to free radical-induced aging. To test this hypothesis, we subjected human scalp skin anagen hair follicles from graying individuals to macroscopic and immunohistomorphometric analysis and organ culture. We found evidence of melanocyte apoptosis and increased oxidative stress in the pigmentary unit of graying hair follicles. The "common" deletion, a marker mitochondrial DNA-deletion for accumulating oxidative stress damage, occurred most prominently in graying hair follicles. Cultured unpigmented hair follicles grew better than pigmented follicles of the same donors. Finally, cultured pigmented hair follicles exposed to exogenous oxidative stress (hydroquinone) showed increased melanocyte apoptosis in the hair bulb. We conclude that oxidative stress is high in hair follicle melanocytes and leads to their selective premature aging and apoptosis. The graying hair follicle, therefore, offers a unique model system to study oxidative stress and aging and to test antiaging therapeutics in their ability to slow down or even stop this process.

  12. Photoexcited riboflavin induces oxidative damage to human serum albumin

    Science.gov (United States)

    Hirakawa, Kazutaka; Yoshioka, Takuto

    2015-08-01

    Photoexcited riboflavin induced damage of human serum albumin (HSA), a water soluble protein, resulting in the diminishment of fluorescence from the tryptophan residue. Because riboflavin hardly photosensitized singlet oxygen generation and sodium azide, a singlet oxygen quencher, did not inhibit protein damage, electron transfer-mediated oxidation of HSA was speculated. Fluorescence lifetime of riboflavin was not affected by HSA, suggesting that the excited triplet state of riboflavin is responsible for protein damage through electron transfer. In addition, the preventive effect of xanthone derivatives, triplet quenchers, on photosensitized protein damage could be evaluated using this photosensitized reaction system of riboflavin and HSA.

  13. Leghemoglobin-derived radicals. Evidence for multiple protein-derived radicals and the initiation of peribacteroid membrane damage

    DEFF Research Database (Denmark)

    Moreau, S; Davies, Michael Jonathan; Mathieu, C

    1996-01-01

    , with the consequent generation of lipid-derived radicals. The formation of such radicals may result in the depletion of membrane antioxidants and the initiation of lipid peroxidation. This transfer of damage from the heme center via the protein surface to neighboring membranes may be of considerable biological......-derived phenoxyl radical present at Tyr-133 in the soybean protein and Tyr-138 in the lupin protein. To obtain further information on these protein radicals and their potential interaction with the physiologically important peribacteroid membrane (which surrounds the microsymbiont in vivo), EPR spin trapping......); these radicals may be side chain- or alpha-carbon-derived, their exact sites have not been determined. Some of these radicals are on the protein surface and may be key intermediates in the formation of protein dimers. These radicals have been shown to be capable of reacting with peribacteroid membrane fractions...

  14. Generation and propagation of radical reactions on proteins

    DEFF Research Database (Denmark)

    Hawkins, C L; Davies, Michael Jonathan

    2001-01-01

    The oxidation of proteins by free radicals is thought to play a major role in many oxidative processes within cells and is implicated in a number of human diseases as well as ageing. This review summarises information on the formation of radicals on peptides and proteins and how radical damage may...... be propagated and transferred within protein structures. The emphasis of this article is primarily on the deleterious actions of radicals generated on proteins, and their mechanisms of action, rather than on enzymatic systems where radicals are deliberately formed as transient intermediates. The final section...

  15. Oxidative damage to fibronectin. 2. The effect of H2O2 and the hydroxyl radical

    International Nuclear Information System (INIS)

    Vissers, M.C.; Winterbourn, C.C.

    1991-01-01

    The effect of H2O2 and the hydroxyl radical (.OH) on fibronectin was investigated. .OH was generated in three ways: (1) by radiolysis with 60Co under N2O, or by the Fenton system using either (2) equimolar Fe(2+)-EDTA and H2O2 or (3) H2O2 and catalytic amounts of Fe(2+)-EDTA recycled with ascorbate. Each system had a different effect. H2O2 alone caused no changes, even at an 800-fold molar excess. Radiolytic .OH caused a rapid loss of tryptophan fluorescence, an increase in bityrosine fluorescence, and extensive crosslinking. The Fenton system using Fe-EDTA, H2O2, and ascorbate caused a loss in tryptophan fluorescence, a smaller increase in bityrosine than was seen with radiolytic .OH, and a threefold increase in carbonyl groups. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis fragmentation of fibronectin was seen. In contrast, when .OH was generated with equimolar Fe-EDTA and H2O2, the only change was a small increase in bityrosine fluorescence at the highest dose of oxidant. None of the systems used affected cysteine. All the changes except the loss of tryptophan by radiolytic .OH were completely inhibited with mannitol. The differences seen with radiolytic .OH and the Fe-EDTA, H2O2, ascorbate system were not solely due to O2 in the latter system since similar results were obtained under N2. The differences between radiolytic .OH and the Fenton systems could be partly due to the components of the latter systems reacting with .OH and thus competing with fibronectin. The authors results demonstrate that the extent and type of fibronectin damage by .OH is dependent on the mode of radical generation

  16. Free Radical Oxidation in Rat Myocardium after Maximum Permissible Hepatic Resection.

    Science.gov (United States)

    Ermolaev, P A; Khramykh, T P; Barskaya, L O

    2016-03-01

    Free radical oxidation in rat myocardial homogenate was studied by chemiluminescent assay during the early terms after maximum permissible liver resection. During this period, activation of free radical oxidation was biphasic. The critical terms characterized by dramatic intensification of free radical oxidation in the myocardium are the first hour and the first day after surgery. The period from 3 to 12 h after surgery, in which the indices of chemiluminescence decrease, can be tentatively termed as the period of "putative wellbeing". Normalization of the free radical oxidation processes in the myocardium occurred by day 7 after surgery.

  17. Selenoprotein P influences colitis-induced tumorigenesis by mediating stemness and oxidative damage

    Science.gov (United States)

    Barrett, Caitlyn W.; Reddy, Vishruth K.; Short, Sarah P.; Motley, Amy K.; Lintel, Mary K.; Bradley, Amber M.; Freeman, Tanner; Vallance, Jefferson; Ning, Wei; Parang, Bobak; Poindexter, Shenika V.; Fingleton, Barbara; Chen, Xi; Washington, Mary K.; Wilson, Keith T.; Shroyer, Noah F.; Hill, Kristina E.; Burk, Raymond F.; Williams, Christopher S.

    2015-01-01

    Patients with inflammatory bowel disease are at increased risk for colon cancer due to augmented oxidative stress. These patients also have compromised antioxidant defenses as the result of nutritional deficiencies. The micronutrient selenium is essential for selenoprotein production and is transported from the liver to target tissues via selenoprotein P (SEPP1). Target tissues also produce SEPP1, which is thought to possess an endogenous antioxidant function. Here, we have shown that mice with Sepp1 haploinsufficiency or mutations that disrupt either the selenium transport or the enzymatic domain of SEPP1 exhibit increased colitis-associated carcinogenesis as the result of increased genomic instability and promotion of a protumorigenic microenvironment. Reduced SEPP1 function markedly increased M2-polarized macrophages, indicating a role for SEPP1 in macrophage polarization and immune function. Furthermore, compared with partial loss, complete loss of SEPP1 substantially reduced tumor burden, in part due to increased apoptosis. Using intestinal organoid cultures, we found that, compared with those from WT animals, Sepp1-null cultures display increased stem cell characteristics that are coupled with increased ROS production, DNA damage, proliferation, decreased cell survival, and modulation of WNT signaling in response to H2O2-mediated oxidative stress. Together, these data demonstrate that SEPP1 influences inflammatory tumorigenesis by affecting genomic stability, the inflammatory microenvironment, and epithelial stem cell functions. PMID:26053663

  18. Oxidative Damage and Cellular Defense Mechanisms in Sea Urchin Models of Aging

    Science.gov (United States)

    Du, Colin; Anderson, Arielle; Lortie, Mae; Parsons, Rachel; Bodnar, Andrea

    2013-01-01

    The free radical or oxidative stress theory of aging proposes that the accumulation of oxidative cellular damage is a major contributor to the aging process and a key determinant of species longevity. This study investigates the oxidative stress theory in a novel model for aging research, the sea urchin. Sea urchins present a unique model for the study of aging due to the existence of species with tremendously different natural life spans including some species with extraordinary longevity and negligible senescence. Cellular oxidative damage, antioxidant capacity and proteasome enzyme activities were measured in the tissues of three sea urchin species: short-lived Lytechinus variegatus, long-lived Strongylocentrotus franciscanus and Strongylocentrotus purpuratus which has an intermediate lifespan. Levels of protein carbonyls and 4-hydroxynonenal (HNE) measured in tissues (muscle, nerve, esophagus, gonad, coelomocytes, ampullae) and 8-hydroxy-2’-deoxyguanosine (8-OHdG) measured in cell-free coelomic fluid showed no general increase with age. The fluorescent age-pigment lipofuscin measured in muscle, nerve and esophagus, increased with age however it appeared to be predominantly extracellular. Antioxidant mechanisms (total antioxidant capacity, superoxide dismutase) and proteasome enzyme activities were maintained with age. In some instances, levels of oxidative damage were lower and antioxidant activity higher in cells or tissues of the long-lived species compared to the short-lived species, however further studies are required to determine the relationship between oxidative damage and longevity in these animals. Consistent with the predictions of the oxidative stress theory of aging, the results suggest that negligible senescence is accompanied by a lack of accumulation of cellular oxidative damage with age and maintenance of antioxidant capacity and proteasome enzyme activities may be important mechanisms to mitigate damage. PMID:23707327

  19. Possible role of Arthrospira platensis in reversing oxidative stress-mediated liver damage in rats exposed to lead.

    Science.gov (United States)

    Khalil, Samah R; Elhady, Walaa M; Elewa, Yaser H A; Abd El-Hameed, Noura E; Ali, Sozan A

    2018-01-01

    Environmental pollutants, particularly metallic elements, mobilized and released into the environment, eventually accumulate in the food chain and thus pose a serious threat to human and animal health. In the present study, the role of Arthrospira (Spirulina platensis; SP) as a protector against oxidative stress-mediated liver damage induced by an exposure to lead acetate (LA; as a metallic pollutant) was assessed. To achieve this aim, rats were orally administered with 300 mg/kg bw SP for 15 days, before and concurrently with an intraperitoneal injection of 50 mg/kg bw LA (6 injections throughout 15 days). As a result, co-administration of SP with LA reduced the amount of lead that accumulated in both blood and liver tissue of the exposed rats and minimized the increased levels of lipid peroxidation, protein oxidation, DNA oxidative damage, and liver enzyme endpoints. In addition, because of SP administration, the levels of depleted biomarkers of antioxidant status and total antioxidant capacity in LA-exposed rats improved. Moreover, SP protected the liver tissue against the changes caused by LA exposure and also decreased the reactivity of HSP70 in the cytoplasm of hepatocytes. Collectively, our data suggest that SP has a potential use as a food supplement in the regions highly polluted with heavy metals such as lead. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  20. Radiation damage to human erythrocytes. Relative contribution of hydroxyl and chloride radicals in N{sub 2}O-saturated buffers

    Energy Technology Data Exchange (ETDEWEB)

    Krokosz, Anita [Department of Molecular Biophysics, University of Lodz, Banacha 12/16, 90 237 Lodz (Poland)], E-mail: krokosz@biol.uni.lodz.pl; Komorowska, Magdalena A.; Szweda-Lewandowska, Zofia [Department of Molecular Biophysics, University of Lodz, Banacha 12/16, 90 237 Lodz (Poland)

    2008-06-15

    The erythrocyte suspensions in Na-phosphate buffered isotonic NaCl solution (PBS) or Na-phosphate isotonic buffer (PB) (hematocrit 1%) were irradiated with the dose of 400 Gy under N{sub 2}O. Erythrocytes were incubated in the medium in which the cells were irradiated or in fresh PBS. The level of damage to cells was estimated on the basis of the course of post-radiation hemolysis and hemoglobin (Hb) oxidation. The medium in which the cells were irradiated and incubated influenced the course of the post-radiation hemolysis and Hb oxidation as well as some other parameters. We discussed the contribution of hydroxyl and chloride radicals in the initiation of erythrocyte damage and oxygen modification of these processes.

  1. Oxidative DNA Damage in Neurons: Implication of Ku in Neuronal Homeostasis and Survival

    Directory of Open Access Journals (Sweden)

    Daniela De Zio

    2012-01-01

    Full Text Available Oxidative DNA damage is produced by reactive oxygen species (ROS which are generated by exogenous and endogenous sources and continuously challenge the cell. One of the most severe DNA lesions is the double-strand break (DSB, which is mainly repaired by nonhomologous end joining (NHEJ pathway in mammals. NHEJ directly joins the broken ends, without using the homologous template. Ku70/86 heterodimer, also known as Ku, is the first component of NHEJ as it directly binds DNA and recruits other NHEJ factors to promote the repair of the broken ends. Neurons are particularly metabolically active, displaying high rates of transcription and translation, which are associated with high metabolic and mitochondrial activity as well as oxygen consumption. In such a way, excessive oxygen radicals can be generated and constantly attack DNA, thereby producing several lesions. This condition, together with defective DNA repair systems, can lead to a high accumulation of DNA damage resulting in neurodegenerative processes and defects in neurodevelopment. In light of recent findings, in this paper, we will discuss the possible implication of Ku in neurodevelopment and in mediating the DNA repair dysfunction observed in certain neurodegenerations.

  2. Vesicular (liposomal and nanoparticulated delivery of curcumin: a comparative study on carbon tetrachloride–mediated oxidative hepatocellular damage in rat model

    Directory of Open Access Journals (Sweden)

    Choudhury ST

    2016-05-01

    Full Text Available Somsubhra Thakur Choudhury,1 Nirmalendu Das,2 Swarupa Ghosh,2 Debasree Ghosh,2 Somsuta Chakraborty,2 Nahid Ali1 1Infectious Diseases and Immunology, 2Drug Development, Diagnostics and Biotechnology, CSIR-Indian Institute of Chemical Biology, Kolkata, West Bengal, India Abstract: The liver plays a vital role in biotransforming and extricating xenobiotics and is thus prone to their toxicities. Short-term administration of carbon tetrachloride (CCl4 causes hepatic inflammation by enhancing cellular reactive oxygen species (ROS level, promoting mitochondrial dysfunction, and inducing cellular apoptosis. Curcumin is well accepted for its antioxidative and anti-inflammatory properties and can be considered as an effective therapeutic agent against hepatotoxicity. However, its therapeutic efficacy is compromised due to its insolubility in water. Vesicular delivery of curcumin can address this limitation and thereby enhance its effectiveness. In this study, it was observed that both liposomal and nanoparticulated formulations of curcumin could increase its efficacy significantly against hepatotoxicity by preventing cellular oxidative stress. However, the best protection could be obtained through the polymeric nanoparticle-mediated delivery of curcumin. Mitochondria have a pivotal role in ROS homeostasis and cell survivability. Along with the maintenance of cellular ROS levels, nanoparticulated curcumin also significantly (P<0.0001 increased cellular antioxidant enzymes, averted excessive mitochondrial destruction, and prevented total liver damage in CCl4-treated rats. The therapy not only prevented cells from oxidative damage but also arrested the intrinsic apoptotic pathway. In addition, it also decreased the fatty changes in hepatocytes, centrizonal necrosis, and portal inflammation evident from the histopathological analysis. To conclude, curcumin-loaded polymeric nanoparticles are more effective in comparison to liposomal curcumin in preventing CCl4

  3. Aromatic-radical oxidation chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Glassman, I.; Brezinsky, K. [Princeton Univ., NJ (United States)

    1993-12-01

    The research effort has focussed on discovering an explanation for the anomalously high CO{sub 2} concentrations observed early in the reaction sequence of the oxidation of cyclopentadiene. To explain this observation, a number of plausible mechanisms have been developed which now await experimental verification. One experimental technique for verifying mechanisms is to probe the reacting system by perturbing the radical concentrations. Two forms of chemical perturbation of the oxidation of cyclopentadiene were begun during this past year--the addition of NO{sub 2} and CO to the reacting mixture.

  4. Evaluation of Cassia tora Linn. against oxidative stress-induced DNA and cell membrane damage

    Directory of Open Access Journals (Sweden)

    R Sunil Kumar

    2017-01-01

    Full Text Available Objective: The present study aims to evaluate antioxidants and protective role of Cassia tora Linn. against oxidative stress-induced DNA and cell membrane damage. Materials and Methods: The total and profiles of flavonoids were identified and quantified through reversed-phase high-performance liquid chromatography. In vitro antioxidant activity was determined using standard antioxidant assays. The protective role of C. tora extracts against oxidative stress-induced DNA and cell membrane damage was examined by electrophoretic and scanning electron microscopic studies, respectively. Results: The total flavonoid content of CtEA was 106.8 ± 2.8 mg/g d.w.QE, CtME was 72.4 ± 1.12 mg/g d.w.QE, and CtWE was 30.4 ± 0.8 mg/g d.w.QE. The concentration of flavonoids present in CtEA in decreasing order: quercetin >kaempferol >epicatechin; in CtME: quercetin >rutin >kaempferol; whereas, in CtWE: quercetin >rutin >kaempferol. The CtEA inhibited free radical-induced red blood cell hemolysis and cell membrane morphology better than CtME as confirmed by a scanning electron micrograph. CtEA also showed better protection than CtME and CtWE against free radical-induced DNA damage as confirmed by electrophoresis. Conclusion: C. tora contains flavonoids and inhibits oxidative stress and can be used for many health benefits and pharmacotherapy.

  5. DNA damage protection and 5-lipoxygenase inhibiting activity of ...

    African Journals Online (AJOL)

    DNA damage caused by free radical is associated with mutation-based health impairment. The protective effect on DNA damage mediated by hydroxyl radical and peroxynitrite radical, and the inhibiting activity on 5-lipoxygenase of areca inflorescence extracts were studied in vitro. The results show that the boiling water ...

  6. Titanium dioxide induced cell damage: A proposed role of the carboxyl radical

    Energy Technology Data Exchange (ETDEWEB)

    Dodd, Nicholas J.F. [Ecotoxicology and Stress Biology Research Centre, School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Jha, Awadhesh N. [Ecotoxicology and Stress Biology Research Centre, School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom)], E-mail: a.jha@plymouth.ac.uk

    2009-01-15

    Titanium dioxide (TiO{sub 2}) nanoparticles have been shown to be genotoxic to cells exposed to ultraviolet A (UVA) radiation. Using the technique of electron spin resonance (ESR) spin trapping, we have confirmed that the primary damaging species produced on irradiation of TiO{sub 2} nanoparticles is the hydroxyl (OH) radical. We have applied this technique to TiO{sub 2}-treated fish and mammalian cells under in vitro conditions and observed the additional formation of carboxyl radical anions (CO{sub 2}{sup -}) and superoxide radical anions (O{sub 2}{sup -}). This novel finding suggests a hitherto unreported pathway for damage, involving primary generation of OH radicals in the cytoplasm, which react to give CO{sub 2}{sup -} radicals. The latter may then react with cellular oxygen to form O{sub 2}{sup -} and genotoxic hydrogen peroxide (H{sub 2}O{sub 2})

  7. Effects of ozone oxidative preconditioning on radiation-induced organ damage in rats

    International Nuclear Information System (INIS)

    Gultekin, Fatma Ayca; Bakkal, Bekir Hakan; Guven, Berrak; Tasdoven, Ilhan; Bektas, Sibel; Can, Murat; Comert, Mustafa

    2013-01-01

    Because radiation-induced cellular damage is attributed primarily to harmful effects of free radicals, molecules with direct free radical scavenging properties are particularly promising as radioprotectors. It has been demonstrated that controlled ozone administration may promote an adaptation to oxidative stress, preventing the damage induced by reactive oxygen species. Thus, we hypothesized that ozone would ameliorate oxidative damage caused by total body irradiation (TBI) with a single dose of 6 Gy in rat liver and ileum tissues. Rats were randomly divided into groups as follows: control group; saline-treated and irradiated (IR) groups; and ozone oxidative preconditioning (OOP) and IR groups. Animals were exposed to TBI after a 5-day intraperitoneal pretreatment with either saline or ozone (1 mg/kg/day). They were decapitated at either 6 h or 72 h after TBI. Plasma, liver and ileum samples were obtained. Serum AST, ALT and TNF-α levels were elevated in the IR groups compared with the control group and were decreased after treatment with OOP. TBI resulted in a significant increase in the levels of MDA in the liver and ileal tissues and a decrease of SOD activities. The results demonstrated that the levels of MDA liver and ileal tissues in irradiated rats that were pretreated with ozone were significantly decreased, while SOD activities were significantly increased. OOP reversed all histopathological alterations induced by irradiation. In conclusion, data obtained from this study indicated that ozone could increase the endogenous antioxidant defense mechanism in rats and there by protect the animals from radiation-induced organ toxicity. (author)

  8. Electron transfer oxidation of DNA radicals by paranitroacetophenone

    Energy Technology Data Exchange (ETDEWEB)

    Whillans, D W; Adams, G E [Mount Vernon Hospital, Northwood (UK)

    1975-12-01

    The reaction of a typical electron-affinic sensitizer, paranitroacetophenone (PNAP) with the model compounds thymine, thymidine, thymidylic acid, deoxyribose and single and double-stranded DNA has been investigated by pulse radiolysis. Radicals formed by one-electron reduction of the bases and of DNA reacted rapidly and efficiently with PNAP by electron transfer. A small yield of transfer (< 10 per cent) was also observed arising from oxidation of the radicals formed by the small proportion of OH which reacted at the sugar moieties in DNA. In contrast, electron transfer oxidation by PNAP of radicals formed by the addition of OH to the base moieties, e.g. thymine, was not an efficient process. Further, addition of the sensitizer to the thymine OH-adduct proceeded at a rate that was too low to measure the pulse radiolysis. We conclude that, since the major sites of OH reaction by DNA are the heterocyclic bases (> 80 per cent), oxidation of the resultant radicals is unlikely to be a major step in the mechanism of sensitization by this typical hypoxic-cell sensitizer.

  9. Antioxidant and DNA Damage Protecting Activity of Exopolysaccharides from the Endophytic Bacterium Bacillus cereus SZ1

    Directory of Open Access Journals (Sweden)

    Li Ping Zheng

    2016-02-01

    Full Text Available An endophytic bacterium was isolated from the Chinese medicinal plant Artemisia annua L. The phylogenetic and physiological characterization indicated that the isolate, strain SZ-1, was Bacillus cereus. The endophyte could produce an exopolysaccharide (EPS at 46 mg/L. The 1,1-diphenyl-2-picrylhydracyl (DPPH radical scavenging activity of the EPS reached more than 50% at 3–5 mg/mL. The EPS was also effective in scavenging superoxide radical in a concentration dependent fashion with an EC50 value of 2.6 mg/mL. The corresponding EC50 for scavenging hydroxyl radical was 3.1 mg/mL. Moreover, phenanthroline-copper complex-mediated chemiluminescent emission of DNA damage was both inhibited and delayed by EPS. The EPS at 0.7–1.7 mg/mL also protected supercoiled DNA strands in plasmid pBR322 against scission induced by Fenton-mediated hydroxyl radical. The preincubation of PC12 cells with the EPS prior to H2O2 exposure increased the cell survival and glutathione (GSH level and catalase (CAT activities, and decreased the level of malondialdehyde (MDA and lactate dehydrogenase (LDH activity in a dose-dependent manner, suggesting a pronounced protective effect against H2O2-induced cytotoxicity. Our study indicated that the EPS could be useful for preventing oxidative DNA damage and cellular oxidation in pharmaceutical and food industries.

  10. Synthesis of Pyrroloquinones via a CAN Mediated Oxidative Free Radical Reaction of 1,3-Dicarbonyl Compounds with Aminoquinones

    Directory of Open Access Journals (Sweden)

    Thao Nguyen

    2013-01-01

    Full Text Available Pyrroloquinone ring systems are important structural units present in many biologically active molecules including a number of marine alkaloids. For example, they are found in a series of marine metabolites, such as tsitsikammamines, zyzzyanones, wakayin, and terreusinone. Several of these alkaloids have exhibited antimicrobial, antimalarial, antifungal, antitumor, and photoprotecting activities. Synthesis of pyrroloquinone unit is the key step in the synthesis of many of these important organic molecules. Here, we present a ceric (IV ammonium nitrate (CAN mediated oxidative free radical cyclization reaction of 1,3-dicarbonyl compounds with aminoquinones as a facile methodology for making various substituted pyrroloquinones. 1,3-dicarbonyl compounds used in this study are ethyl acetoacetate, acetylacetone, benzoyl acetone, and N,N-dimethyl acetoacetamide. The aminoquinones used in this study are 2-(benzylaminonaphthalene-1,4-dione and 6-(benzylamino-1-tosyl-1H-indole-4,7-dione. The yields of the synthesized pyrroloquinones ranged from 23–91%.

  11. Effect of metal complexation to anti-inflammatory over the action against oxidative and free radicals: ketoprofen action

    International Nuclear Information System (INIS)

    Manente, Francine Alessandra; Mello, Lucas Rosolen de Almeida; Vellosa, Jose Carlos Rebuglio; Khalil, Omar Arafat Kdudsi; Carvalho, Claudio Teodoro de; Bannach, Gilbert

    2011-01-01

    Free radicals are highly reactive species generated in living organisms for the purpose of protection. However, in some circumstances, they are responsible for the occurrence or aggravation of tissue damage. Many anti-inflammatory drugs have a direct effect on free radicals and not radical reactive species, which contributes to its actions against inflammation. Ketoprofen is a nonsteroidal anti-inflammatory agent that generates free radicals by photo irradiation and has an important hemolytic effect with that. The complexation of metals to different drugs has been used as a strategy to improve the pharmacological action of different molecules and reduce their side effects. This paper presents the results of ketoprofen and their metallic complexes action on erythrocytes and free radicals. It was observed that the cerium enhances the scavenger properties of ketoprofen on free radicals, while copper enhances its action over non-radical oxidants. Copper also reduced the hemolytic effect presented by ketoprofen meanwhile its cerium derivative maintained it. (author)

  12. Effect of seven Indian plant extracts on Fenton reaction-mediated damage to DNA constituents.

    Science.gov (United States)

    Kar, Indrani; Chattopadhyaya, Rajagopal

    2017-11-01

    The influences of substoichiometric amounts of seven plant extracts in the Fenton reaction-mediated damage to deoxynucleosides, deoxynucleoside monophosphates, deoxynucleoside triphosphates, and supercoiled plasmid DNA were studied to rationalize anticancer properties reported in some of these extracts. Extracts from Acacia catechu, Emblica officinalis, Spondias dulcis, Terminalia belerica, Terminalia chebula, as well as gallic acid, epicatechin, chebulagic acid and chebulinic acid enhance the extent of damage in Fenton reactions with all monomeric substrates but protect supercoiled plasmid DNA, compared to standard Fenton reactions. The damage to pyrimidine nucleosides/nucleotides is enhanced by these extracts and compounds to a greater extent than for purine ones in a concentration dependent manner. Dolichos biflorus and Hemidesmus indicus extracts generally do not show this enhancement for the monomeric substrates though they protect plasmid DNA. Compared to standard Fenton reactions for deoxynucleosides with ethanol, the presence of these five plant extracts render ethanol scavenging less effective as the radical is generated in the vicinity of the target. Since substoichiometric amounts of these extracts and the four compounds produce this effect, a catalytic mechanism involving the presence of a ternary complex of the nucleoside/nucleotide substrate, a plant compound and the hydroxyl radical is proposed. Such a mechanism cannot operate for plasmid DNA as the planar rings in the extract compounds cannot stack with the duplex DNA bases. These plant extracts, by enhancing Fenton reaction-mediated damage to deoxynucleoside triphosphates, slow down DNA replication in rapidly dividing cancer cells, thus contributing to their anticancer properties.

  13. The role of free radicals and antioxidants in reproduction.

    Science.gov (United States)

    Agarwal, Ashok; Gupta, Sajal; Sikka, Suresh

    2006-06-01

    This review summarizes the role of free radicals and oxidative stress in the pathophysiology of human reproduction. An extensive review of the literature on the role of oxidative stress in influencing assisted reproduction and its outcome is described in this article. Free radicals or reactive oxygen species mediate their action through many of the proinflammatory cytokines and this mechanism has been proposed as a common underlying factor for endometriosis, ovarian cancer, polycystic ovary disease, and various other pathologies affecting the female reproductive process, as highlighted in this review. Oxidative stress, sperm DNA damage, and apoptosis have been implicated in male infertility. Elevated reactive oxygen species levels correlate with the poor fertility outcomes seen in the assisted reproductive technology setting. Oxidative stress has been implicated in male and female infertility, including fetal dysmorphogenesis, abortions, and intrauterine growth restriction. Accurate evaluation of seminal oxidative stress by standardized assays may help in the diagnosis and management of male infertility. There is evidence in the literature on the beneficial effects of oral antioxidant supplementation in male infertility. Current ongoing trials will provide answers on the safety and effectiveness of antioxidants in improving maternal and fetal outcomes. Further studies need to be conducted to determine if antioxidant supplementation will prevent fetal developmental defects in high-risk pregnancy with diabetes.

  14. Effect of Free Radicals & Antioxidants on Oxidative Stress: A Review

    Directory of Open Access Journals (Sweden)

    Ashok Shinde

    2012-01-01

    Full Text Available Recently free radicals have attracted tremendous importance in the field of medicine including dentistry and molecular biology. Free radicals can be either harmful or helpful to the body. When there is an imbalance between formation and removal of free radicals then a condition called as oxidative stress is developed in body. To counteract these free radicals body has protective antioxidant mechanisms which have abilities to lower incidence of various human morbidities and mortalities. Many research groups in the past have tried to study and confirm oxidative stress. Many authors also have studied role of antioxidants in reducing oxidative stress. They have come across with controversial results and furthermore it is not yet fully confirmed whether oxidative stress increases the need for dietary antioxidants. Recently, an association between periodontitis and cardiovascular disease has received considerable attention. Various forms of antioxidants have been introduced as an approach to fight dental diseases and improve general gingival health. The implication of oxidative stress in the etiology of many chronic and degenerative diseases suggests that antioxidant therapy represents a promising avenue for treatment. This study was conducted with the objective of reviewing articles relating to this subject. A Pub Med search of all articles containing key words free radicals, oxidative stress, and antioxidants was done. A review of these articles was undertaken.

  15. OGG1 Involvement in High Glucose-Mediated Enhancement of Bupivacaine-Induced Oxidative DNA Damage in SH-SY5Y Cells

    Science.gov (United States)

    Liu, Zhong-Jie; Zhao, Wei; Zhang, Qing-Guo; Li, Le; Lai, Lu-Ying; Jiang, Shan; Xu, Shi-Yuan

    2015-01-01

    Hyperglycemia can inhibit expression of the 8-oxoG-DNA glycosylase (OGG1) which is one of the key repair enzymes for DNA oxidative damage. The effect of hyperglycemia on OGG1 expression in response to local anesthetics-induced DNA damage is unknown. This study was designed to determine whether high glucose inhibits OGG1 expression and aggravates bupivacaine-induced DNA damage via reactive oxygen species (ROS). SH-SY5Y cells were cultured with or without 50 mM glucose for 8 days before they were treated with 1.5 mM bupivacaine for 24 h. OGG1 expression was measured by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot. ROS was estimated using the redox-sensitive fluorescent dye DCFH-DA. DNA damage was investigated with immunostaining for 8-oxodG and comet assays. OGG1 expression was inhibited in cells exposed to high glucose with concomitant increase in ROS production and more severe DNA damage as compared to control culture conditions, and these changes were further exacerbated by bupivacaine. Treatment with the antioxidant N-acetyl-L-cysteine (NAC) prevented high glucose and bupivacaine mediated increase in ROS production and restored functional expression of OGG1, which lead to attenuated high glucose-mediated exacerbation of bupivacaine neurotoxicity. Our findings indicate that subjects with diabetes may experience more detrimental effects following bupivacaine use. PMID:26161242

  16. OGG1 Involvement in High Glucose-Mediated Enhancement of Bupivacaine-Induced Oxidative DNA Damage in SH-SY5Y Cells

    Directory of Open Access Journals (Sweden)

    Zhong-Jie Liu

    2015-01-01

    Full Text Available Hyperglycemia can inhibit expression of the 8-oxoG-DNA glycosylase (OGG1 which is one of the key repair enzymes for DNA oxidative damage. The effect of hyperglycemia on OGG1 expression in response to local anesthetics-induced DNA damage is unknown. This study was designed to determine whether high glucose inhibits OGG1 expression and aggravates bupivacaine-induced DNA damage via reactive oxygen species (ROS. SH-SY5Y cells were cultured with or without 50 mM glucose for 8 days before they were treated with 1.5 mM bupivacaine for 24 h. OGG1 expression was measured by quantitative real-time polymerase chain reaction (qRT-PCR and western blot. ROS was estimated using the redox-sensitive fluorescent dye DCFH-DA. DNA damage was investigated with immunostaining for 8-oxodG and comet assays. OGG1 expression was inhibited in cells exposed to high glucose with concomitant increase in ROS production and more severe DNA damage as compared to control culture conditions, and these changes were further exacerbated by bupivacaine. Treatment with the antioxidant N-acetyl-L-cysteine (NAC prevented high glucose and bupivacaine mediated increase in ROS production and restored functional expression of OGG1, which lead to attenuated high glucose-mediated exacerbation of bupivacaine neurotoxicity. Our findings indicate that subjects with diabetes may experience more detrimental effects following bupivacaine use.

  17. Epiphytes modulate Posidonia oceanica photosynthetic production, energetic balance, antioxidant mechanisms and oxidative damage

    Directory of Open Access Journals (Sweden)

    Monya Mendes Costa

    2015-12-01

    Full Text Available Epiphytes impose physical barriers to light penetration into seagrass leaves causing shading, which may decrease the production of oxygen reactive species (ROS, but also constitute a physical aggression that may trigger the production of ROS, leading to oxidative damage. Here we investigate the effects of epiphytes on Posidonia oceanica under both interactive perspectives, light attenuation and oxidative stress. Specifically the role of epiphytes in net photosynthesis, chlorophyll a and b, photoprotection (Violaxanthin+Anteraxanthin+Zeaxanthin cycle, soluble sugar and starch contents, enzymatic (ascorbate peroxidase (APX and dehydroascorbate reductase (DHAR and global (trolox equivalent antioxidant capacity (TEAC and oxygen radical antioxidant capacity (ORAC antioxidant responses, phenolics and oxidative damage (malondialdehyde are tested. Leaves with epiphytes showed higher chlorophyll b and lower content in VAZ cycle carotenoids. Epiphyte shading was the probable reason for the lower VAZ de-epoxidation-ratio of leaves with epiphytes. In spite of being shaded, leaves with epiphytes showed higher antioxidant levels, indicating that epiphytes trigger the production of ROS. Both ORAC and TEAC and also APX and DHAR activities were higher in leaves with epiphytes, indicating that this response was related with its presence. Malondialdehyde concentrations also suggest oxidative damage caused by epiphytes. We conclude that the epiphyte load causes oxidative stress in P. oceanica and the mechanisms to scavenge ROS were not completely effective to avoid cell damage.

  18. Imidazoline and imidazolidine nitroxides as controlling agents in nitroxide-mediated pseudoliving radical polymerization

    Science.gov (United States)

    Edeleva, M. V.; Marque, S. R. A.; Bagryanskaya, E. G.

    2018-04-01

    Controlled, or pseudoliving, radical polymerization provides unique opportunities for the synthesis of structurally diverse polymers with a narrow molecular-weight distribution. These reactions occur under relatively mild conditions with broad tolerance to functional groups in the monomers. The nitroxide-mediated pseudoliving radical polymerization is of particular interest for the synthesis of polymers for biomedical applications. This review briefly describes one of the mechanisms of controlled radical polymerization. The studies dealing with the use of imidazoline and imidazolidine nitroxides as controlling agents for nitroxide-mediated pseudoliving radical polymerization of various monomers are summarized and analyzed. The publications addressing the key steps of the controlled radical polymerization in the presence of imidazoline and imidazolidine nitroxides and new approaches to nitroxide-mediated polymerization based on protonation of both nitroxides and monomers are considered. The bibliography includes 154 references.

  19. Oxidative stress

    Directory of Open Access Journals (Sweden)

    Stevanović Jelka

    2012-01-01

    Full Text Available The unceasing need for oxygen is in contradiction to the fact that it is in fact toxic to mammals. Namely, its monovalent reduction can have as a consequence the production of short-living, chemically very active free radicals and certain non-radical agents (nitrogen-oxide, superoxide-anion-radicals, hydroxyl radicals, peroxyl radicals, singlet oxygen, peroxynitrite, hydrogen peroxide, hypochlorous acid, and others. There is no doubt that they have numerous positive roles, but when their production is stepped up to such an extent that the organism cannot eliminate them with its antioxidants (superoxide-dismutase, glutathione-peroxidase, catalase, transferrin, ceruloplasmin, reduced glutathion, and others, a series of disorders is developed that are jointly called „oxidative stress.“ The reactive oxygen species which characterize oxidative stress are capable of attacking all main classes of biological macromolecules, actually proteins, DNA and RNA molecules, and in particular lipids. The free radicals influence lipid peroxidation in cellular membranes, oxidative damage to DNA and RNA molecules, the development of genetic mutations, fragmentation, and the altered function of various protein molecules. All of this results in the following consequences: disrupted permeability of cellular membranes, disrupted cellular signalization and ion homeostasis, reduced or loss of function of damaged proteins, and similar. That is why the free radicals that are released during oxidative stress are considered pathogenic agents of numerous diseases and ageing. The type of damage that will occur, and when it will take place, depends on the nature of the free radicals, their site of action and their source. [Projekat Ministarstva nauke Republike Srbije, br. 173034, br. 175061 i br. 31085

  20. Retinal Diseases Associated with Oxidative Stress and the Effects of a Free Radical Scavenger (Edaravone)

    Science.gov (United States)

    Hara, Hideaki

    2017-01-01

    Oxidative stress plays a pivotal role in developing and accelerating retinal diseases including age-related macular degeneration (AMD), glaucoma, diabetic retinopathy (DR), and retinal vein occlusion (RVO). An excess amount of reactive oxygen species (ROS) can lead to functional and morphological impairments in retinal pigment epithelium (RPE), endothelial cells, and retinal ganglion cells (RGCs). Here we demonstrate that edaravone, a free radical scavenger, decreased apoptotic cell death, oxidative damage to DNA and lipids, and angiogenesis through inhibiting JNK and p38 MAPK pathways in AMD, glaucoma, DR, and RVO animal models. These data suggest that the therapeutic strategy for targeting oxidative stress may be important for the treatment of these ocular diseases, and edaravone may be useful for treating retinal diseases associated with oxidative stress. PMID:28194256

  1. Comparative study of radical oxidation of DNA and its nucleosides by hydroxyl radicals and ferryl ions generated by the Fenton reaction

    International Nuclear Information System (INIS)

    Mouret, J.F.; Berger, M.; Anselmino, C.; Polverelli, M.; Cadet, J.

    1991-01-01

    A comparative study of the reaction of hydroxyl radicals and Fenton type oxidative species with DNA and 2'-deoxyribonucleosides was investigated. This study was based on the characterization of the diamagnetic products resulting from the chemical transformation of the transient radicals. Emphasis was placed on the radical oxidative reactions of the purine nucleosides. It is interesting to note that oxidative purine radicals can be reduced by reagents such as ascorbic acid or N,N,N',N'-tetramethyl-1, 4-p-phenylenediamine. The observed differences in the nature of the decomposition products resulting from the Fenton reaction are not consistent with the nature of the oxidative species (hydroxyl radicals or ferryl ions) involved, but due to the presence of ferrous sulfate [fr

  2. Bilirubin and its oxidation products damage brain white matter

    Science.gov (United States)

    Lakovic, Katarina; Ai, Jinglu; D'Abbondanza, Josephine; Tariq, Asma; Sabri, Mohammed; Alarfaj, Abdullah K; Vasdev, Punarjot; Macdonald, Robert Loch

    2014-01-01

    Brain injury after intracerebral hemorrhage (ICH) occurs in cortex and white matter and may be mediated by blood breakdown products, including hemoglobin and heme. Effects of blood breakdown products, bilirubin and bilirubin oxidation products, have not been widely investigated in adult brain. Here, we first determined the effect of bilirubin and its oxidation products on the structure and function of white matter in vitro using brain slices. Subsequently, we determined whether these compounds have an effect on the structure and function of white matter in vivo. In all, 0.5 mmol/L bilirubin treatment significantly damaged both the function and the structure of myelinated axons but not the unmyelinated axons in brain slices. Toxicity of bilirubin in vitro was prevented by dimethyl sulfoxide. Bilirubin oxidation products (BOXes) may be responsible for the toxicity of bilirubin. In in vivo experiments, unmyelinated axons were found more susceptible to damage from bilirubin injection. These results suggest that unmyelinated axons may have a major role in white-matter damage in vivo. Since bilirubin and BOXes appear in a delayed manner after ICH, preventing their toxic effects may be worth investigating therapeutically. Dimethyl sulfoxide or its structurally related derivatives may have a potential therapeutic value at antagonizing axonal damage after hemorrhagic stroke. PMID:25160671

  3. Allylthioketone Mediated Free Radical Polymerization of Methacrylates

    Directory of Open Access Journals (Sweden)

    Feng Zhong

    2017-11-01

    Full Text Available By combination of high trapping free radical efficiency of the thioketone and resonance of the allylic radical, a new type of mediating agent, 1,3,3-triphenylprop-2-ene-1-thione (TPPT has been successfully synthesized, and then is used to study controlled free radical polymerization of methacrylates. Very stable TPPT radicals at the end of poly(methyl methacrylate (PMMA are detected in the polymerization of MMA using TPPT and AIBN as the control agent and initiator. The MALDI-TOF MS spectra are used to identify terminal groups of the resultant poly(glycidyl methacrylate (PGMA, and major component of the obtained polymer has the structure, (CH32(CNC-PGMA-C7H9O3. Chain extension reaction tests ascertain formation of the dead polymers during the polymer storage and purification process of the polymers. Owing to very slow fragmentation reaction of the TPPT-terminated polymethacrylate radical and addition reaction of this radical with a primary radical, the growing chain radicals are difficult to be regenerated, leading to an unobvious change of the molecular weight with monomer conversion. The molecular weights of polymers can be controlled by the ratios of monomer/initiator and TPPT/initiator. However, the first order kinetics of the polymerization and the polymers with narrow polydispersity are obtained, and these phenomena are discussed. This study provides useful information on how to design a better controlling agent.

  4. Flow Giese reaction using cyanoborohydride as a radical mediator

    Directory of Open Access Journals (Sweden)

    Takahide Fukuyama

    2013-09-01

    Full Text Available Tin-free Giese reactions, employing primary, secondary, and tertiary alkyl iodides as radical precursors, ethyl acrylate as a radical trap, and sodium cyanoborohydride as a radical mediator, were examined in a continuous flow system. With the use of an automated flow microreactor, flow reaction conditions for the Giese reaction were quickly optimized, and it was found that a reaction temperature of 70 °C in combination with a residence time of 10–15 minutes gave good yields of the desired addition products.

  5. Essential fatty acid-rich diets protect against striatal oxidative damage induced by quinolinic acid in rats.

    Science.gov (United States)

    Morales-Martínez, Adriana; Sánchez-Mendoza, Alicia; Martínez-Lazcano, Juan Carlos; Pineda-Farías, Jorge Baruch; Montes, Sergio; El-Hafidi, Mohammed; Martínez-Gopar, Pablo Eliasib; Tristán-López, Luis; Pérez-Neri, Iván; Zamorano-Carrillo, Absalom; Castro, Nelly; Ríos, Camilo; Pérez-Severiano, Francisca

    2017-09-01

    Essential fatty acids have an important effect on oxidative stress-related diseases. The Huntington's disease (HD) is a hereditary neurologic disorder in which oxidative stress caused by free radicals is an important damage mechanism. The HD experimental model induced by quinolinic acid (QUIN) has been widely used to evaluate therapeutic effects of antioxidant compounds. The aim of this study was to test whether the fatty acid content in olive- or fish-oil-rich diet prevents against QUIN-related oxidative damage in rats. Rats were fed during 20 days with an olive- or a fish-oil-rich diet (15% w/w). Posterior to diet period, rats were striatally microinjected with QUIN (240 nmol/µl) or saline solution. Then, we evaluated the neurological damage, oxidative status, and gamma isoform of the peroxisome proliferator-activated receptor (PPARγ) expression. Results showed that fatty acid-rich diet, mainly by fish oil, reduced circling behavior, prevented the fall in GABA levels, increased PPARγ expression, and prevented oxidative damage in striatal tissue. In addition none of the enriched diets exerted changes neither on triglycerides or cholesterol blood levels, nor or hepatic function. This study suggests that olive- and fish-oil-rich diets exert neuroprotective effects.

  6. Oxidative Damage Caused by Common Foodborne Pathogenic Bacteria in Egg Yolk

    Directory of Open Access Journals (Sweden)

    Reyhaneh Afshordi

    2016-02-01

    Full Text Available Background: Bacteria in foodstuff are the most important agent of foodborne disease. Aside from their infectious effects, obligate aerobes have a respiratory metabolism with oxygen as the terminal electron acceptor. Therefore, they can produce reactive oxygen species and free radicals in contaminated food. Malondialdehyde (MDA is a product of lipid peroxidation used as an indicator of oxidative stress. Objectives: This study aimed to evaluate the oxidative damage produced by two common food pathogenic bacteria in foodstuff. Materials and Methods: The egg yolks were incubated with different dilutions (105,106, and 107 of Staphylococcus aureus and Salmonella enteritidis at 37°C for 20 hours. The level of MDA in egg yolk was measured by fast and simple enzymatic or colorimetric methods, such as the thiobarbituric acid reactive species method. Results: The high group (107 had a higher MDA level of 1.97 ± 0.11 (μg MDA/g in S. aureus and 1.65 ± 0.27 (mg MDA/L in S. enteritidis than the control (0.90 ± 0.13 mg MDA/L. Conclusions: We concluded that common food pathogenic bacteria can induce oxidative damage in foodstuff aside from other common problems. Heating or sterilization methods cannot protect foodstuff from the damage caused by the presence of pathogenic bacteria.

  7. Identification of mitochondrial electron transport chain-mediated NADH radical formation by EPR spin-trapping techniques.

    Science.gov (United States)

    Matsuzaki, Satoshi; Kotake, Yashige; Humphries, Kenneth M

    2011-12-20

    The mitochondrial electron transport chain (ETC) is a major source of free radical production. However, due to the highly reactive nature of radical species and their short lifetimes, accurate detection and identification of these molecules in biological systems is challenging. The aim of this investigation was to determine the free radical species produced from the mitochondrial ETC by utilizing EPR spin-trapping techniques and the recently commercialized spin-trap, 5-(2,2-dimethyl-1,3-propoxycyclophosphoryl)-5-methyl-1-pyrroline N-oxide (CYPMPO). We demonstrate that this spin-trap has the preferential quality of having minimal mitochondrial toxicity at concentrations required for radical detection. In rat heart mitochondria and submitochondrial particles supplied with NADH, the major species detected under physiological pH was a carbon-centered radical adduct, indicated by markedly large hyperfine coupling constant with hydrogen (a(H) > 2.0 mT). In the presence of the ETC inhibitors, the carbon-centered radical formation was increased and exhibited NADH concentration dependency. The same carbon-centered radical could also be produced with the NAD biosynthesis precursor, nicotinamide mononucleotide, in the presence of a catalytic amount of NADH. The results support the conclusion that the observed species is a complex I derived NADH radical. The formation of the NADH radical could be blocked by hydroxyl radical scavengers but not SOD. In vitro experiments confirmed that an NADH-radical is readily formed by hydroxyl radical but not superoxide anion, further implicating hydroxyl radical as an upstream mediator of NADH radical production. These findings demonstrate the identification of a novel mitochondrial radical species with potential physiological significance and highlight the diverse mechanisms and sites of production within the ETC.

  8. Some reactions of oxidizing radicals with enzymes in aqueous solution

    International Nuclear Information System (INIS)

    Cundall, R.B.; Bisby, R.H.; Hoe, S.T.; Sims, H.E.; Anderson, R.F.

    1979-01-01

    A range of oxidizing radicals including some inorganic radical anions and the superoxide radical, can be generated by radiolysis of aqueous solutions. These radicals are more selective in their reactions with amino acids than the hydroxyl radical. Factors controlling the apparent reactivity of radical anions with proteins, such as free radical equilibria and ion-binding, are described. The superoxide radical inactivates papain by reaction with the cysteine residue. This reaction has been studied in solutions subjected to radiations of varying linear energy transfer. (Auth.)

  9. DNA damage produced by exposure of supercoiled plasmid DNA to high- and low-LET ionizing radiation: Effects of hydroxyl radical quenchers. DNA breakage, neutrons, OH radicals

    International Nuclear Information System (INIS)

    Peak, J.G.; Ito, T.; Peak, M.J.; Robb, F.T.

    1994-01-01

    A supercoiled plasmid of 7300 base pairs was isolated and exposed in an aqueous environment to 60 Co γ rays and JANUS 0.85 MeV fission-spectrum neutrons. Dose responses for the production of single-strand breaks (SSBs), double-strand breaks (DSBs) and alkali-labile sites (ALSs) were compared with computations made from the conversion of the supercoil to its relaxed and linear forms. The relative biological effectiveness (RBE) for production of SSBs and DSBs was similar to that previously measured in the cellular environment. The RBE for destruction of genetic transforming activity of M13 viral DNA followed that for DNA damage. This is in contrast to the situation for biological effects such as lethality, mutagenesis, and cellular transformation measured in mammalian cells, where the RBE values are reversed. The role of hydroxyl (OH) radical in DNA damage induction by neutrons was investigated by exposure of plasmid in the presence of known quenchers of this species. Of four quenchers tested, all were able to reduce the yields of both SSBs and DSBs. These findings are consistent with a model for SSB and DSB induction by high linear energy transfer that involves OH radical mediation

  10. Inducible nitric oxide synthase catalyzes ethanol oxidation to α-hydroxyethyl radical and acetaldehyde

    International Nuclear Information System (INIS)

    Porasuphatana, Supatra; Weaver, John; Rosen, Gerald M.

    2006-01-01

    The physiologic function of nitric oxide synthases, independent of the isozyme, is well established, metabolizing L-arginine to L-citrulline and nitric oxide (NO). This enzyme can also transfer electrons to O 2 , affording superoxide (O 2 · - ) and hydrogen peroxide (H 2 O 2 ). We have demonstrated that NOS1, in the presence of L-arginine, can biotransform ethanol (EtOH) to α-hydroxyethyl radical (CH 3 ·CHOH). We now report that a competent NOS2 with L-arginine can, like NOS1, oxidize EtOH to CH 3 ·CHOH. Once this free radical is formed, it is metabolized to acetaldehyde as shown by LC-ESI-MS/MS and HPLC analysis. These observations suggest that NOS2 can behave similarly to cytochrome P-450 in the catalysis of acetaldehyde formation from ethanol via the generation of α-hydroxyethyl radical when L-arginine is present

  11. Comparative time-courses of copper-ion-mediated protein and lipid oxidation in low-density lipoprotein

    DEFF Research Database (Denmark)

    Knott, Heather M; Baoutina, Anna; Davies, Michael Jonathan

    2002-01-01

    Free radicals damage both lipids and proteins and evidence has accumulated for the presence of both oxidised lipids and proteins in aged tissue samples as well as those from a variety of pathologies including atherosclerosis, diabetes, and Parkinson's disease. Oxidation of the protein and lipid...

  12. SIRT3 mediates decrease of oxidative damage and prevention of ageing in porcine fetal fibroblasts.

    Science.gov (United States)

    Xie, Xiaoxian; Wang, Liangliang; Zhao, Binggong; Chen, Yangyang; Li, Jiaqi

    2017-05-15

    Sirtuin 3 (SIRT3) is a mitochondria-specific protein required for the deacetylation of metabolic enzymes and the action of oxidative phosphorylation by acting as a nicotinamide adenine dinucleotide (NAD + )-dependent deacetylase. SIRT3 increases oxidative stress resistance and prevents mitochondrial decay associated with ageing in response to caloric restriction. However, the effects of SIRT3 on oxidative damage and ageing are not well understood. We investigated the physiological functions of porcine SIRT3 on the damage and ageing in porcine fetal fibroblasts (PFFs). Overexpression and knockdown of SIRT3 were confirmed by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analysis, respectively. All cells were treated with three different stress reagents 12-o-tetradecanoylphorbol-13-acetate (TPA), methanesulfonic acid methylester (MMS), and tert-butylhydroperoxide (t-BHP), respectively, and then examined by flow cytometry following JC-1 (5, 5', 6, 6'-tetrachloro-1, 1', 3, 3'-tetraethylbenzimidazol-carbocyanine iodide) staining. SIRT3 overexpression enhanced the ability of superoxide dismutase 2 (SOD2) to reduce cellular reactive oxygen species (ROS), which further decreased the damage to the membranes and the organelles of the cells, especially to mitochondria. It inhibited the initial decrease of mitochondrial membrane potential, and prevented the decrease of adenosine triphosphate (ATP) production and activity of Nampt. In contrast, SIRT3 knockdown reduced the ability of SOD2 to increase cellular ROS which was directly correlated with stress-induced oxidative damage and ageing in PFFs. Our findings identify one function of SIRT3 in PFFs was to dampen cytotoxicity, and, therefore, to decrease oxidative damage and attenuate ageing possibly by enhancing the activity of SOD2. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Study progress on free radicals and graves disease

    International Nuclear Information System (INIS)

    Zhang Ruiguo; Jin Jianhua

    2009-01-01

    Free radical-mediated oxidative injury has been closely implicated in the occurrence and development of many diseases. Graves disease was also accompanied by changes of the free radicals, especially for reactive oxygen species and reactive nitrogen, et al, and the oxidative stress can cause a certain degree of injury on the thyroid and other human important organs. Antithyroid drug and 131 I treatment of Graves disease, the oxidative and antioxidative parameters can also be changed. (authors)

  14. Radical chemistry of epigallocatechin gallate and its relevance to protein damage

    DEFF Research Database (Denmark)

    Hagerman, Ann E; Dean, Roger T; Davies, Michael Jonathan

    2003-01-01

    The radical chemistry of the plant polyphenolics epigallocatechin gallate (EGCG) and epigallocatechin (EGC) were investigated using electron paramagnetic resonance spectroscopy. Radical species formed spontaneously in aqueous solutions at low pH without external oxidant and were spin stabilized...... redox potentials of EGCG and EGC varied from 1000 mV at pH 3 to 400 mV at pH 8. The polyphenolics did not produce hydroxyl radicals unless reduced metal ions such as iron(II) were added to the system. Zinc(II)-stabilized EGCG radicals were more effective protein-precipitating agents than unoxidized EGCG...

  15. Retinal Diseases Associated with Oxidative Stress and the Effects of a Free Radical Scavenger (Edaravone

    Directory of Open Access Journals (Sweden)

    Tomomi Masuda

    2017-01-01

    Full Text Available Oxidative stress plays a pivotal role in developing and accelerating retinal diseases including age-related macular degeneration (AMD, glaucoma, diabetic retinopathy (DR, and retinal vein occlusion (RVO. An excess amount of reactive oxygen species (ROS can lead to functional and morphological impairments in retinal pigment epithelium (RPE, endothelial cells, and retinal ganglion cells (RGCs. Here we demonstrate that edaravone, a free radical scavenger, decreased apoptotic cell death, oxidative damage to DNA and lipids, and angiogenesis through inhibiting JNK and p38 MAPK pathways in AMD, glaucoma, DR, and RVO animal models. These data suggest that the therapeutic strategy for targeting oxidative stress may be important for the treatment of these ocular diseases, and edaravone may be useful for treating retinal diseases associated with oxidative stress.

  16. Metallothionein blocks oxidative DNA damage induced by acute inorganic arsenic exposure

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Wei, E-mail: qu@niehs.nih.gov; Waalkes, Michael P.

    2015-02-01

    We studied how protein metallothionein (MT) impacts arsenic-induced oxidative DNA damage (ODD) using cells that poorly express MT (MT-I/II double knockout embryonic cells; called MT-null cells) and wild-type (WT) MT competent cells. Arsenic (as NaAsO{sub 2}) was less cytolethal over 24 h in WT cells (LC{sub 50} = 11.0 ± 1.3 μM; mean ± SEM) than in MT-null cells (LC{sub 50} = 5.6 ± 1.2 μM). ODD was measured by the immuno-spin trapping method. Arsenic (1 or 5 μM; 24 h) induced much less ODD in WT cells (121% and 141% of control, respectively) than in MT-null cells (202% and 260%). In WT cells arsenic caused concentration-dependent increases in MT expression (transcript and protein), and in the metal-responsive transcription factor-1 (MTF-1), which is required to induce the MT gene. In contrast, basal MT levels were not detectable in MT-null cells and unaltered by arsenic exposure. Transfection of MT-I gene into the MT-null cells markedly reduced arsenic-induced ODD levels. The transport genes, Abcc1 and Abcc2 were increased by arsenic in WT cells but either showed no or very limited increases in MT-null cells. Arsenic caused increases in oxidant stress defense genes HO-1 and GSTα2 in both WT and MT-null cells, but to much higher levels in WT cells. WT cells appear more adept at activating metal transport systems and oxidant response genes, although the role of MT in these responses is unclear. Overall, MT protects against arsenic-induced ODD in MT competent cells by potential sequestration of scavenging oxidant radicals and/or arsenic. - Highlights: • Metallothionein blocks arsenic toxicity. • Metallothionein reduces arsenic-induced DNA damage. • Metallothionein may bind arsenic or radicals produced by arsenic.

  17. Free radicals created by radiation and aging symptoms

    International Nuclear Information System (INIS)

    Ashry, O.M.

    2012-01-01

    The universality of aging implies that its cause is basically the same in all species. A free radical hypothesis of aging has been proposed that the free radicals produced during normal metabolism of the cell over time damage DNA and other macromolecules leading to degenerative diseases, malignancies, and eventual death of vital cells which in turn causes aging and death of the organism. This hypothesis is supported by several observations. Radiation produces its biologic effect through free radical formation and causes premature aging. Second, the age pigment lipo fuscin is associated with lipid peroxidation. The hypothesis that oxygen radicals play a role in aging is also supported by the observation that, in general, long-lived species produce less endogenous free oxygen radicals because of their lower metabolic rate. Long-lived animals also have more superoxide dismutase than do their short-lived counterparts, and animal species with the longest lifespan have the highest levels of superoxide dismutase. Oxidative DNA damage is rapidly and effectively repaired. It has been estimated that there are several thousand oxidative DNA damage sites in a human cell every day, and the majority of these are repaired. However, a small fraction of unrepaired lesions could cause permanent changes in DNA and might be a major contributor to aging and cancer. A consequence of the free radical hypothesis of aging is the idea that free radical scavenging agents might be used to prevent aging. (author)

  18. Urinary excretion of biomarkers of oxidatively damaged DNA and RNA in hereditary hemochromatosis

    DEFF Research Database (Denmark)

    Broedbaek, Kasper; Poulsen, Henrik E; Weimann, Allan

    2009-01-01

    Oxidatively generated damage to nucleic acids is considered to play a significant role in carcinogenesis, and it has been shown that people with hereditary hemochromatosis are at increased risk of cancer. In this study we used a new refined liquid chromatography-tandem mass spectrometry method...... of the iron overload seen in this disease. By this mechanism cellular damage resulting in end organ damage, typically seen in the liver of such patients, may be mediated....

  19. Aerosol Fragmentation Driven by Coupling of Acid-Base and Free-Radical Chemistry in the Heterogeneous Oxidation of Aqueous Citric Acid by OH Radicals.

    Science.gov (United States)

    Liu, Matthew J; Wiegel, Aaron A; Wilson, Kevin R; Houle, Frances A

    2017-08-10

    A key uncertainty in the heterogeneous oxidation of carboxylic acids by hydroxyl radicals (OH) in aqueous-phase aerosol is how the free-radical reaction pathways might be altered by acid-base chemistry. In particular, if acid-base reactions occur concurrently with acyloxy radical formation and unimolecular decomposition of alkoxy radicals, there is a possibility that differences in reaction pathways impact the partitioning of organic carbon between the gas and aqueous phases. To examine these questions, a kinetic model is developed for the OH-initiated oxidation of citric acid aerosol at high relative humidity. The reaction scheme, containing both free-radical and acid-base elementary reaction steps with physically validated rate coefficients, accurately predicts the experimentally observed molecular composition, particle size, and average elemental composition of the aerosol upon oxidation. The difference between the two reaction channels centers on the reactivity of carboxylic acid groups. Free-radical reactions mainly add functional groups to the carbon skeleton of neutral citric acid, because carboxylic acid moieties deactivate the unimolecular fragmentation of alkoxy radicals. In contrast, the conjugate carboxylate groups originating from acid-base equilibria activate both acyloxy radical formation and carbon-carbon bond scission of alkoxy radicals, leading to the formation of low molecular weight, highly oxidized products such as oxalic and mesoxalic acid. Subsequent hydration of carbonyl groups in the oxidized products increases the aerosol hygroscopicity and accelerates the substantial water uptake and volume growth that accompany oxidation. These results frame the oxidative lifecycle of atmospheric aerosol: it is governed by feedbacks between reactions that first increase the particle oxidation state, then eventually promote water uptake and acid-base chemistry. When coupled to free-radical reactions, acid-base channels lead to formation of low molecular

  20. Oxidation and Free Radical Decay in Vitamin E-stabilized, Radiation Cross-linked UHMWPE

    International Nuclear Information System (INIS)

    Oral, E.

    2006-01-01

    A novel a-tocopherol (vitamin E, α-T)-stabilized, cross-linked ultra-high molecular weight polyethylene (UHMWPE) (αTPE) was developed for total joint arthroplasty as a bearing surface with low wear and improved mechanical properties. Accelerated aging showed α-T protects irradiated UHMWPE against oxidation. However, accelerated aging may not truly reflect in vivo and shelf oxidation. We used real-time aging to monitor the evolution of oxidation and free radical signals of α-T to determine the mechanism of oxidative stability. UHMWPE blocks (30x30x10 mm) were machined and γ-irradiated (85 kGy) in argon. The blocks were doped in α-T for 5 hours at 120 degree and homogenized for 64 hours at 120 degree in argon, packaged in vacuum and γ-sterilized (25 kGy). Samples were aged in air at room temperature, in air at 40 degree and in water at 40 degree. Measurements were at 1, 2, 3, 4 and 7 months. Sections cut from the aged blocks (150μm) were boiled in hexane overnight to extract free species and evaluated by FTIR. Oxidation indices were calculated by taking the area under the carbonyl peak and normalizing it to a skeletal peak. ESR was used to determine the content and type of free radicals. Control was 100-kGy irradiated, unstabilized UHMWPE. αTPE showed a small amount of oxidation, which stabilized after 2 months. This indicated that the decay of the hydroperoxides formed by the reaction of the residual free radicals with oxygen was exhausted by α-T due to its ability to scavenge free radicals. In contrast, control UHMWPE continued to oxidize because the residual free radicals likely continued to form hydroperoxides and additional free radicals, furthering the oxidation reactions. There was a shift in the free radical signature of both αTPE and control from the sextet alkyl/allyl radicals to a sharp singlet during aging. Most likely, trapped free radicals move along the crystal stems until they react with another free radical or until they reach the crystal

  1. Atmospheric Oxidation Mechanism of Furfural Initiated by Hydroxyl Radicals.

    Science.gov (United States)

    Zhao, Xiaocan; Wang, Liming

    2017-05-04

    Furfural is emitted into the atmosphere because of its potential applications as an intermediate to alkane fuels from biomass, industrial usages, and biomass burning. The kinetic and mechanistic information on the furfural chemistry is necessary to assess the fate of furfural in the atmosphere and its impact on the air quality. Here we studied the atmospheric oxidation mechanisms of furfural initiated by the OH radicals using quantum chemistry and kinetic calculations. The reaction of OH and furfural was initiated mainly by OH additions to C 2 and C 5 positions, forming R2 and R5 adducts, which could undergo rapid ring-breakage to form R2B and R5B, respectively. Our calculations showed that these intermediate radicals reacted rather slowly with O 2 under the atmospheric conditions because the additions of O 2 to these radicals are only slightly exothermic and highly reversible. Alternatively, these radicals would react directly with O 3 , NO 2 , HO 2 /RO 2 , etc. Namely, the atmospheric oxidation of furfural would unlikely result in ozone formation. Under typical atmospheric conditions, the main products in OH-initiated furfural oxidation include 2-oxo-3-pentene-1,5-dialdehyde, 5-hydroxy-2(5H)-furanone, 4-oxo-2- butenoic acid, and 2,5-furandione. These compounds will likely stay in the gas phase and are subject to further photo-oxidation.

  2. Liposomal Antioxidants for Protection against Oxidant-Induced Damage

    Directory of Open Access Journals (Sweden)

    Zacharias E. Suntres

    2011-01-01

    Full Text Available Reactive oxygen species (ROS, including superoxide anion, hydrogen peroxide, and hydroxyl radical, can be formed as normal products of aerobic metabolism and can be produced at elevated rates under pathophysiological conditions. Overproduction and/or insufficient removal of ROS result in significant damage to cell structure and functions. In vitro studies showed that antioxidants, when applied directly and at relatively high concentrations to cellular systems, are effective in conferring protection against the damaging actions of ROS, but results from animal and human studies showed that several antioxidants provide only modest benefit and even possible harm. Antioxidants have yet to be rendered into reliable and safe therapies because of their poor solubility, inability to cross membrane barriers, extensive first-pass metabolism, and rapid clearance from cells. There is considerable interest towards the development of drug-delivery systems that would result in the selective delivery of antioxidants to tissues in sufficient concentrations to ameliorate oxidant-induced tissue injuries. Liposomes are biocompatible, biodegradable, and nontoxic artificial phospholipid vesicles that offer the possibility of carrying hydrophilic, hydrophobic, and amphiphilic molecules. This paper focus on the use of liposomes for the delivery of antioxidants in the prevention or treatment of pathological conditions related to oxidative stress.

  3. Human low density lipoprotein (LDL) oxidation by metmyoglobin/H2O2: involvement of α-tocopheroxyl and phosphatidylcholine alkoxyl radicals

    International Nuclear Information System (INIS)

    Witting, P.K.; Willhite, C.A.; Stocker, R.; Davies, M.J.

    1998-01-01

    Full text: Metmyoglobin (metMb) and H 2 O 2 can oxidize low density lipoprotein (LDL) in vitro; formation of such oxidized LDL may be atherogenic. The role of α-tocopherol (α-TOH) in LDL oxidation by peroxidases, such as metMb is unclear. Herein we show that during metMb/H 2 O 2 -induced oxidation of native, α-TOH-containing, LDL, α-tocopheroxyl radical (α-TO) and hydroperoxides and hydroxides of cholesteryl esters (CE-O(O)H) and phosphatidylcholine (PC-O(O)H) accumulated concomitantly with α-TOH consumption. Accumulation of CE-O(O)H was dependent on, and correlated with, LDL's α-TOH content indicating that α-TO . acted as a chain-transfer agent and propagated LDL lipid peroxidation via tocopherol-mediated peroxidation (TMP). Further, the ratio of accumulating CE-O(O)H to PC-O(O)H remained constant in the presence α-TOH. Subsequent to α-TOH depletion, CE-O(O)H continued to accumulate, albeit at a lower rate than in the presence of α-TOH. This was accompanied by depletion of PC-OOH, a rapid increase in the CE-O(O)H/PC-O(O)H ratio, formation of lipid-derived alkoxyl radicals and phosphatidylcholine hydroxides (PC-OH), and accumulation of a second organic radical, characterized by a broad singlet EPR signal. The latter persisted for several hours at 37 deg C. We conclude that metMb/H 2 O 2 -induced peroxidation of LDL lipids is not inhibited by α-TOH and occurs initially via TMP. After α-TOH depletion, cholesteryl esters peroxidize at higher fractional rates than surface phospholipids, and this appears to be mediated via reactions involving alkoxyl radicals derived from the peroxidatic activity of metMb on PC-OO

  4. Hypochlorite- and hypobromite-mediated radical formation and its role in cell lysis

    DEFF Research Database (Denmark)

    Hawkins, C L; Brown, B E; Davies, Michael Jonathan

    2001-01-01

    . In this study it is shown that HOBr induces red blood cell lysis at approximately 10-fold lower concentrations than HOCl, whereas with monocyte (THP1) and macrophage (J774) cells HOCl and HOBr induce lysis at similar concentrations. The role of radical formation during lysis has been investigated by EPR spin...... trapping, and it is shown that reaction of both oxidants with each cell type generates cell-derived radicals. Red blood cells exposed to nonlytic doses of HOCl generate novel nitrogen-centered radicals whose formation is GSH dependent. In contrast, HOBr gives rise to nitrogen-centered, membrane......-derived protein radicals. With lytic doses of either oxidant, protein (probably hemoglobin)-derived, nitrogen-centered radicals are observed. Unlike the red blood cells, treatment of monocytes and macrophages with HOCl gives significant radical formation only under conditions where cell lysis occurs concurrently...

  5. Chronic nandrolone administration promotes oxidative stress, induction of pro-inflammatory cytokine and TNF-α mediated apoptosis in the kidneys of CD1 treated mice

    Energy Technology Data Exchange (ETDEWEB)

    Riezzo, Irene; Turillazzi, Emanuela; Bello, Stefania; Cantatore, Santina [Department of Forensic Pathology, University of Foggia, Foggia (Italy); Cerretani, Daniela [Pharmacology Unit, Department of Medicine, Surgery and Neuroscience, University of Siena, Siena (Italy); Di Paolo, Marco [Department of Forensic Pathology, University of Pisa, Pisa (Italy); Fiaschi, Anna Ida [Pharmacology Unit, Department of Medicine, Surgery and Neuroscience, University of Siena, Siena (Italy); Frati, Paola [Department of Anatomical, Histological, Forensic and Orthopaedic Sciences, University of Rome Sapienza, Viale Regina Elena 336, 00161 Rome (Italy); Neri, Margherita [Department of Forensic Pathology, University of Foggia, Foggia (Italy); Pedretti, Monica [Department of Forensic Pathology, University of Pisa, Pisa (Italy); Fineschi, Vittorio, E-mail: vfinesc@tin.it [Department of Anatomical, Histological, Forensic and Orthopaedic Sciences, University of Rome Sapienza, Viale Regina Elena 336, 00161 Rome (Italy)

    2014-10-01

    Nandrolone decanoate administration and strenuous exercise increase the extent of renal damage in response to renal toxic injury. We studied the role played by oxidative stress in the apoptotic response caused by nandrolone decanoate in the kidneys of strength-trained male CD1 mice. To measure cytosolic enzyme activity, glutathione peroxidase (GPx), glutathione reductase (GR) and malondialdehyde (MDA) were determined after nandrolone treatment. An immunohistochemical study and Western blot analysis were performed to evaluate cell apoptosis and to measure the effects of renal expression of inflammatory mediators (IL-1β, TNF-α) on the induction of apoptosis (HSP90, TUNEL). Dose-related oxidative damage in the kidneys of treated mice is shown by an increase in MDA levels and by a reduction of antioxidant enzyme GR and GPx activities, resulting in the kidney's reduced radical scavenging ability. Renal specimens of the treated group showed relevant glomeruli alterations and increased immunostaining and protein expressions, which manifested significant focal segmental glomerulosclerosis. The induction of proinflammatory cytokine expression levels was confirmed by Western blot analysis. Long-term administration of nandrolone promotes oxidative injury in the mouse kidneys. TNF-α mediated injury due to nandrolone in renal cells appears to play a role in the activation of both the intrinsic and extrinsic apoptosis pathways. - Highlights: • We analyze abuse of nandrolone decanoate in strength-trained male CD1 mice. • Nandrolone decanoate administration increases oxidative stress. • Increased cytokine expressions were observed. • Renal apoptosis was described. • Long-term administration of nandrolone promotes oxidative injury in mice kidney.

  6. Chronic nandrolone administration promotes oxidative stress, induction of pro-inflammatory cytokine and TNF-α mediated apoptosis in the kidneys of CD1 treated mice

    International Nuclear Information System (INIS)

    Riezzo, Irene; Turillazzi, Emanuela; Bello, Stefania; Cantatore, Santina; Cerretani, Daniela; Di Paolo, Marco; Fiaschi, Anna Ida; Frati, Paola; Neri, Margherita; Pedretti, Monica; Fineschi, Vittorio

    2014-01-01

    Nandrolone decanoate administration and strenuous exercise increase the extent of renal damage in response to renal toxic injury. We studied the role played by oxidative stress in the apoptotic response caused by nandrolone decanoate in the kidneys of strength-trained male CD1 mice. To measure cytosolic enzyme activity, glutathione peroxidase (GPx), glutathione reductase (GR) and malondialdehyde (MDA) were determined after nandrolone treatment. An immunohistochemical study and Western blot analysis were performed to evaluate cell apoptosis and to measure the effects of renal expression of inflammatory mediators (IL-1β, TNF-α) on the induction of apoptosis (HSP90, TUNEL). Dose-related oxidative damage in the kidneys of treated mice is shown by an increase in MDA levels and by a reduction of antioxidant enzyme GR and GPx activities, resulting in the kidney's reduced radical scavenging ability. Renal specimens of the treated group showed relevant glomeruli alterations and increased immunostaining and protein expressions, which manifested significant focal segmental glomerulosclerosis. The induction of proinflammatory cytokine expression levels was confirmed by Western blot analysis. Long-term administration of nandrolone promotes oxidative injury in the mouse kidneys. TNF-α mediated injury due to nandrolone in renal cells appears to play a role in the activation of both the intrinsic and extrinsic apoptosis pathways. - Highlights: • We analyze abuse of nandrolone decanoate in strength-trained male CD1 mice. • Nandrolone decanoate administration increases oxidative stress. • Increased cytokine expressions were observed. • Renal apoptosis was described. • Long-term administration of nandrolone promotes oxidative injury in mice kidney

  7. Nitroxide-mediated controlled radical polymerisation: towards control of molar mass Controlled Radical Polymerisation

    NARCIS (Netherlands)

    Bon, S.A.F.; Bergman, F.A.C.; Es, van J.J.G.S.; Klumperman, B.; German, A.L.; Matyjaszewski, K.

    1998-01-01

    The mechanism of the TEMPO-mediated controlled radical polymerization of styrene in bulk is discussed. It is shown that the isotropic correlation time (tc) of a nitroxide can be used as a measure of the diffusive rate coefficient of trapping (ketD). A general empirical relationship for the density

  8. Deciphering free-radical code of radiation effects

    International Nuclear Information System (INIS)

    Volovyk, S.; Bazyka, D.; Loganovsky, K.; Bebeshko, V.

    2007-01-01

    Complete text of publication follows. Objective: Ionizing radiation is fundamental environmental factor for life origin and evolution. Free radicals, primordial 'sea' for life conceiving and existence, induced by cosmic and terrestrial background radiation, are evolutionally archetypal, ubiquitous, and omnipotent in physiological- pathophysiological dichotomy. Classical free-radical paradigm in radiation biology and medicine, focused in essence on oxidative damage, needs new conceptualization and generalization. Methods: Suggested novel insights into free radicals dual immanent nature and functions in organism systems are based on original concepts of radicals dynamic charge transfer (CT) - redox ambivalence (interactional nucleo-, electro-, and ambiphilicity spectrum); pertinent chemical reactivity and selectivity delocalization model; physiological functional ambivalence and complementarity, and dynamic free-radical homeostasis. Results: Subtle perturbations in radicals CT spatiotemporal homeodynamics, in responsive signaling / controlling networks, concomitant alterations in genes expression, transcription, and apoptosis, redox control of mitochondrial ET chain, telomere/telomerase balance, DNA CT, circadian clock, hemispheric biochemical dominance/accentuation, including alteration of nitric oxide-superoxide complementarity, membranes permeability, neurotransmission pattern, synaptic circuitry, etc under radiation exposure have more fundamental impact on organism systems (especially CNS and CVS) deterioration than simple radicals inflicted oxidative (nitrosative) damage of cellular constituents. Conclusions: This novel conceptualization of free-radical paradigm constitutes new dimension in deciphering molecular mechanisms of radiation effects on subtle borderline norm-pathology and continuity-discontinuity dichotomy in organisms systems disorders - CT(redox)omics, which involves investigation of CT, redox, and spin states of free radicals, DNA bases

  9. Antioxidative effects of fermented sesame sauce against hydrogen peroxide-induced oxidative damage in LLC-PK1 porcine renal tubule cells

    Science.gov (United States)

    Song, Jia-Le; Choi, Jung-Ho; Seo, Jae-Hoon; Kil, Jeung-Ha

    2014-01-01

    BACKGROUND/OBJECTIVES This study was performed to investigate the in vitro antioxidant and cytoprotective effects of fermented sesame sauce (FSeS) against hydrogen peroxide (H2O2)-induced oxidative damage in renal proximal tubule LLC-PK1 cells. MATERIALS/METHODS 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl radical (•OH), and H2O2 scavenging assay was used to evaluate the in vitro antioxidant activity of FSeS. To investigate the cytoprotective effect of FSeS against H2O2-induced oxidative damage in LLC-PK1 cells, the cellular levels of reactive oxygen species (ROS), lipid peroxidation, and endogenous antioxidant enzymes including catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GSH-px) were measured. RESULTS The ability of FSeS to scavenge DPPH, •OH and H2O2 was greater than that of FSS and AHSS. FSeS also significantly inhibited H2O2-induced (500 µM) oxidative damage in the LLC-PK1 cells compared to FSS and AHSS (P sauces, FSeS also significantly increased cellular CAT, SOD, and GSH-px activities and mRNA expression (P < 0.05). CONCULUSIONS These results from the present study suggest that FSeS is an effective radical scavenger and protects against H2O2-induced oxidative damage in LLC-PK1 cells by reducing ROS levels, inhibiting lipid peroxidation, and stimulating antioxidant enzyme activity. PMID:24741396

  10. Antioxidant mediated response of Scoparia dulcis in noise-induced redox imbalance and immunohistochemical changes in rat brain.

    Science.gov (United States)

    Wankhar, Wankupar; Srinivasan, Sakthivel; Rajan, Ravindran; Sheeladevi, Rathinasamy

    2017-01-19

    Noise has been regarded as an environmental/occupational stressor that causes damages to both auditory and non-auditory organs. Prolonged exposure to these mediators of stress has often resulted in detrimental effect, where oxidative/nitrosative stress plays a major role. Hence, it would be appropriate to examine the possible role of free radicals in brain discrete regions and the "antioxidants" mediated response of S. dulcis. Animals were subjected to noise stress for 15 days (100 dB/4 hours/day) and estimation of endogenous free radical and antioxidant activity were carried out on brain discrete regions (the cerebral cortex, cerebellum, brainstem, striatum, hippocampus and hypothalamus). The result showed that exposure to noise could alleviate endogenous free radical generation and altered antioxidant status in brain discrete regions when compared to that of the control groups. This alleviated free radical generation (H 2 O 2 and NO) is well supported by an upregulated protein expression on immunohistochemistry of both iNOS and nNOS in the cerebral cortex on exposure to noise stress. These findings suggest that increased free radical generation and altered anti-oxidative status can cause redox imbalance in the brain discrete regions. However, free radical scavenging activity of the plant was evident as the noise exposed group treated with S. dulcis[200 mg/(kg·b·w)] displayed a therapeutic effect by decreasing the free radical level and regulate the anti-oxidative status to that of control animals. Hence, it can be concluded that the efficacy of S. dulcis could be attributed to its free radical scavenging activity and anti-oxidative property.

  11. Oxidation of benzene by radiolytically produced OH radicals. [x rays

    Energy Technology Data Exchange (ETDEWEB)

    Klein, G W; Schuler, R H [Carnegie-Mellon Univ., Pittsburgh, Pa. (USA)

    1978-01-01

    The radiolysis of N/sub 2/O saturated-aqueous solutions of benzene-/sup 14/C has been examined using radio-liquid chromatographic methods to follow the quantitative aspects of the reactions of hydroxycyclohexadienyl radicals. In the absence of a radical oxidant, at least five important products are produced. The total yield of 5.8 observed for the incorporation of benzene into products accounts for essentially all of the radicals initially produced from the water. Dimeric products predominate with a total yield of 4.1. Phenol is produced with a yield of only 0.8 indicating a disproportionation/combination ratio for hydroxycyclohexadienyl radicals of < = 0.4. In the presence of 2mM ferricyanide the hydroxycyclohexadienyl radicals are quantitatively oxidized to phenol with no trace (< 1%) remaining of dimeric or other high molecular weight products. The initial yield for phenol formation (6.0 molecules/100 eV) provides a measure for OH production in N/sub 2/O saturated aqueous solutions.

  12. Assessment of DNA damage and oxidative stress induced by radiation in Eisenia fetida

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Tae Ho; Kim, Jin Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Nili, Mohammad [Dawnesh Radiation Research Institute, Barcelona (Spain)

    2012-04-15

    Exposure of eukaryotic cells to ionizing radiation results in the immediate formation of free radicals and the occurrence of oxidative cell damage. Recently International Commission on Radiological Protection (ICRP) requires the effect data of ionizing radiation on non-human biota for the radiological protection of the environment. Based on their radioecological properties and their important role in the soil ecosystem, earthworms have been identified by the ICRP as one of the reference animals and plants (RAPs) to be used in environmental radiation protection. The investigation shows that oxidative stress is closely related to the exposed dose of radiation in the environment. To evaluate oxidative stress by ionizing radiation in the earthworm, we performed several experiments. The comet assay is known as a measurement which is one of the best techniques in assessing the DNA damage by oxidative stress. The SOD is a key enzyme in protecting cells against oxidative stress. An increase in the level of antioxidant enzyme such as SOD indicated that the exposure to radiation caused stress responses. Glutathione oxidation is considered as a maker for detection of reactive oxygen species (ROS). The GSSG levels increased progressively with increased exposure dose of ionizing radiation, which suggested a dose-dependent ROS generation.

  13. Role of enzymatic free radical scavengers in management of oxidative stress in autoimmune disorders.

    Science.gov (United States)

    Srivastava, Shikha; Singh, Deependra; Patel, Satish; Singh, Manju R

    2017-08-01

    Autoimmune disorders are distinct with over production and accumulation of free radicals due to its undisclosed genesis. The cause of numerous disorders as cancer, arthritis, psoriasis, diabetes, alzheimer's, cardiovascular disease, Parkinson's, respiratory distress syndrome, colitis, crohn's, pulmonary fibrosis, obesity and ageing have been associated with immune dysfunction and oxidative stress. In an oxidative stress, reactive oxygen species generally provoke the series of oxidation at cellular level. The buildup of free radicals in turn triggers various inflammatory cells causing release of various inflammatory interleukins, cytokines, chemokines, and tumor necrosis factors which mediate signal transduction and transcription pathways as nuclear factor- kappa B (NF-κB), signal transducer and activator of transcription 3 (STAT3), hypoxia-inducible factor-1 (HIF-1α) and nuclear factor-erythroid 2-related factor (Nrf2). The imbalance could only be combat by supplementing natural defensive antioxidant enzymes such as superoxide dismutase and catalase. The efficiency of these enzymes is enhanced by use of colloidal carriers which include cellular carriers, vesicular and particulate systems like erythrocytes, leukocytes, platelets, liposomes, transferosomes, solid lipid nanoparticles, microspheres, emulsions. Thus this review provides a platform for understanding importance of antioxidant enzymes and its therapeutic applications in treatment of various autoimmune disorders. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Cytosolic NADP(+)-dependent isocitrate dehydrogenase status modulates oxidative damage to cells.

    Science.gov (United States)

    Lee, Su Min; Koh, Ho-Jin; Park, Dong-Chan; Song, Byoung J; Huh, Tae-Lin; Park, Jeen-Woo

    2002-06-01

    NADPH is an important cofactor in many biosynthesis pathways and the regeneration of reduced glutathione, critically important in cellular defense against oxidative damage. It is mainly produced by glucose 6-phosphate dehydrogenase (G6PD), malic enzyme, and the cytosolic form of NADP(+)-dependent isocitrate dehydrogenase (IDPc). Little information is available about the role of IDPc in antioxidant defense. In this study we investigated the role of IDPc against cytotoxicity induced by oxidative stress by comparing the relative degree of cellular responses in three different NIH3T3 cells with stable transfection with the cDNA for mouse IDPc in sense and antisense orientations, where IDPc activities were 3-4-fold higher and 35% lower, respectively, than that in the parental cells carrying the vector alone. Although the activities of other antioxidant enzymes, such as superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase, and G6PD, were comparable in all transformed cells, the ratio of GSSG to total glutathione was significantly higher in the cells expressing the lower level of IDPc. This finding indicates that IDPc is essential for the efficient glutathione recycling. Upon transient exposure to increasing concentrations of H(2)O(2) or menadione, an intracellular source of free radicals and reactive oxygen species, the cells with low levels of IDPc became more sensitive to oxidative damage by H(2)O(2) or menadione. Lipid peroxidation, oxidative DNA damage, and intracellular peroxide generation were higher in the cell-line expressing the lower level of IDPc. However, the cells with the highly over-expressed IDPc exhibited enhanced resistance against oxidative stress, compared to the control cells. This study provides direct evidence correlating the activities of IDPc and the maintenance of the cellular redox state, suggesting that IDPc plays an important role in cellular defense against oxidative stress.

  15. Oxidative stress and enzymatic scavenging of superoxide radicals induced by solar UV-B radiation in Ulva canopies from southern Spain

    Directory of Open Access Journals (Sweden)

    Kai Bischof

    2003-09-01

    Full Text Available The generation of reactive oxygen species (ROS and scavenging of the superoxide radical by superoxide dismutase (SOD was studied in mat-like canopies of the green macroalga Ulva rotundata Bliding in a tidal brine pond system in southern Spain. Artificial canopies were covered with different cut-off filters, generating different radiation conditions. ROS and SOD were assessed after three days of exposure. ROS induced lipid peroxidation depended on the position of individual thalli within the canopy and on radiation conditions. Samples exposed to the full solar spectrum were most affected, whereas samples either exposed to photosynthetically active radiation (PAR alone or UV radiation without PAR exhibited fewer peroxidation products. The activity of SOD appeared to be controlled by the impinging UV-A and UV-B radiation and also increased in response to oxidative stress. The results provide evidence for additive effects of high PAR and UV-B under field conditions and support the previously proposed hypothesis that UV-B effects are mediated by an inhibition of the xanthophyll cycle, which increases ROS production and, consequently, causes oxidative damage to components of the photosynthetic machinery, such as proteins and pigments.

  16. Oxidative Stress in Oral Diseases: Understanding Its Relation with Other Systemic Diseases

    Directory of Open Access Journals (Sweden)

    Jaya Kumar

    2017-09-01

    Full Text Available Oxidative stress occurs in diabetes, various cancers, liver diseases, stroke, rheumatoid arthritis, chronic inflammation, and other degenerative diseases related to the nervous system. The free radicals have deleterious effect on various organs of the body. This is due to lipid peroxidation and irreversible protein modification that leads to cellular apoptosis or programmed cell death. During recent years, there is a rise in the oral diseases related to oxidative stress. Oxidative stress in oral disease is related to other systemic diseases in the body such as periodontitis, cardiovascular, pancreatic, gastric, and liver diseases. In the present review, we discuss the various pathways that mediate oxidative cellular damage. Numerous pathways mediate oxidative cellular damage and these include caspase pathway, PERK/NRF2 pathway, NADPH oxidase 4 pathways and JNK/mitogen-activated protein (MAP kinase pathway. We also discuss the role of inflammatory markers, lipid peroxidation, and role of oxygen species linked to oxidative stress. Knowledge of different pathways, role of inflammatory markers, and importance of low-density lipoprotein, fibrinogen, creatinine, nitric oxide, nitrates, and highly sensitive C-reactive proteins may be helpful in understanding the pathogenesis and plan better treatment for oral diseases which involve oxidative stress.

  17. Photodynamically generated bovine serum albumin radicals

    DEFF Research Database (Denmark)

    Silvester, J A; Timmins, G S; Davies, Michael Jonathan

    1998-01-01

    Porphyrin-sensitized photoxidation of bovine serum albumin (BSA) results in oxidation of the protein at (at least) two different, specific sites: the Cys-34 residue giving rise to a thiyl radical (RS.); and one or both of the tryptophan residues (Trp-134 and Trp-214) resulting in the formation...... of tertiary carbon-centred radicals and disruption of the tryptophan ring system. In the case of porphyrins such as hematoporphyrin, which bind at specific sites on BSA, these species appear to arise via long-range transfer of damage within the protein structure, as the binding site is some distance from...... the ultimate site of radical formation. This transfer of damage is shown to depend on a number of factors including the conformation of the protein, the presence of blocking groups and pH. Alteration of the protein conformation results in radical formation at additional (or alternative) sites, as does blocking...

  18. Participation of oxidized sulfur center in intramolecular free radical processes in the model organic compounds of biological importance

    International Nuclear Information System (INIS)

    Pogocki, D.M.

    2004-01-01

    The pathogenesis of neurodegenerative diseases such as prion diseases (Creutzfeldt-Jacob disease) and Alzheimer's disease is strongly associated with the presence of β-amyloid peptide (βA) and prion protein (hPrP) in the brain tissue. Both macromolecules contain methionine (Met) residues. Their presence seems to be responsible for unique redox properties of βA and hPrP. These residues may undergo relatively easy autooxidation and/or metal-catalysed oxidation. The presented studies were focused on the potential function of Met residues as antioxidants or pro-oxidants and on their role in radical-mediated oxidation of peptides and proteins. The role of S-, O-, N- and C-centered radicals generated in various oligopeptides containing Met and relevant model compounds has been examined in detail with respect to formation of 2c-3e bonds, redox processes, fragmentation and their mutual interconversion. In order to achieve these goals several experimental radiation, photochemical, and molecular modelling methods were applied. The experimental and molecular modelling results show significant influence of functional neighbouring groups and conformational flexibility of a peptide backbone on the oxidative reduction pathway in oligopeptides containing single and multiple Met residues. The results presented here allow for better understanding of the known propensities of βA and hPrP to reduce transition metals and to form reactive oxygen species and free radicals. (author)

  19. Oxidative damage and neurodegeneration in manganese-induced neurotoxicity

    International Nuclear Information System (INIS)

    Milatovic, Dejan; Zaja-Milatovic, Snjezana; Gupta, Ramesh C.; Yu, Yingchun; Aschner, Michael

    2009-01-01

    Exposure to excessive manganese (Mn) levels results in neurotoxicity to the extrapyramidal system and the development of Parkinson's disease (PD)-like movement disorder, referred to as manganism. Although the mechanisms by which Mn induces neuronal damage are not well defined, its neurotoxicity appears to be regulated by a number of factors, including oxidative injury, mitochondrial dysfunction and neuroinflammation. To investigate the mechanisms underlying Mn neurotoxicity, we studied the effects of Mn on reactive oxygen species (ROS) formation, changes in high-energy phosphates (HEP), neuroinflammation mediators and associated neuronal dysfunctions both in vitro and in vivo. Primary cortical neuronal cultures showed concentration-dependent alterations in biomarkers of oxidative damage, F 2 -isoprostanes (F 2 -IsoPs) and mitochondrial dysfunction (ATP), as early as 2 h following Mn exposure. Treatment of neurons with 500 μM Mn also resulted in time-dependent increases in the levels of the inflammatory biomarker, prostaglandin E 2 (PGE 2 ). In vivo analyses corroborated these findings, establishing that either a single or three (100 mg/kg, s.c.) Mn injections (days 1, 4 and 7) induced significant increases in F 2 -IsoPs and PGE 2 in adult mouse brain 24 h following the last injection. Quantitative morphometric analyses of Golgi-impregnated striatal sections from mice exposed to single or three Mn injections revealed progressive spine degeneration and dendritic damage of medium spiny neurons (MSNs). These findings suggest that oxidative stress, mitochondrial dysfunction and neuroinflammation are underlying mechanisms in Mn-induced neurodegeneration.

  20. Free radicals and related reactive species as mediators of tissue injury and disease: implications for Health.

    Science.gov (United States)

    Kehrer, James P; Klotz, Lars-Oliver

    2015-01-01

    A radical is any molecule that contains one or more unpaired electrons. Radicals are normal products of many metabolic pathways. Some exist in a controlled (caged) form as they perform essential functions. Others exist in a free form and interact with various tissue components. Such interactions can cause both acute and chronic dysfunction, but can also provide essential control of redox regulated signaling pathways. The potential roles of endogenous or xenobiotic-derived free radicals in several human pathologies have stimulated extensive research linking the toxicity of numerous xenobiotics and disease processes to a free radical mechanism. In recent years, improvements in analytical methodologies, as well as the realization that subtle effects induced by free radicals and oxidants are important in modulating cellular signaling, have greatly improved our understanding of the roles of these reactive species in toxic mechanisms and disease processes. However, because free radical-mediated changes are pervasive, and a consequence as well as a cause of injury, whether such species are a major cause of tissue injury and human disease remains unclear. This concern is supported by the fact that the bulk of antioxidant defenses are enzymatic and the findings of numerous studies showing that exogenously administered small molecule antioxidants are unable to affect the course of most toxicities and diseases purported to have a free radical mechanism. This review discusses cellular sources of various radical species and their reactions with vital cellular constituents, and provides examples of selected disease processes that may have a free radical component.

  1. The mitochondrial free radical theory of aging.

    Science.gov (United States)

    Barja, Gustavo

    2014-01-01

    The mitochondrial free radical theory of aging is reviewed. Only two parameters currently correlate with species longevity in the right sense: the mitochondrial rate of reactive oxygen species (mitROS) production and the degree of fatty acid unsaturation of tissue membranes. Both are low in long-lived animals. In addition, the best-known manipulation that extends longevity, dietary restriction, also decreases the rate of mitROS production and oxidative damage to mtDNA. The same occurs during protein restriction as well as during methionine restriction. These two manipulations also increase maximum longevity in rodents. The decrease in mitROS generation and oxidative stress that takes place in caloric restriction seems to be due to restriction of a single dietary substance: methionine. The information available supports a mitochondrial free radical theory of aging focused on low generation of endogenous damage and low sensitivity of membranes to oxidation in long-lived animals. © 2014 Elsevier Inc. All rights reserved.

  2. Oxidative stress evoked damages on rat sperm and attenuated antioxidant status on consumption of aspartame.

    Science.gov (United States)

    Ashok, I; Poornima, P S; Wankhar, D; Ravindran, R; Sheeladevi, R

    2017-07-01

    Although several studies on toxic effect of aspartame metabolite have been studied, controversial reports over the use of aspartame owing to the fact that it releases methanol as one of its metabolite during metabolism exist. This present study is proposed to investigate whether aspartame (40 mg kg -1 b.wt) administration for 90 days could induce oxidative stress and alter antioxidant status of epididymal sperm in Wistar strain male albino rats. To mimic the human methanol metabolism, methotrexate (MTX)-treated rats were included to study the effects of aspartame. Oral intubations of FDA approved 40 mg kg -1 b.wt aspartame were given daily for 90 days to Wistar strain male albino rats and studied along with controls and MTX-treated controls. Sperm count, viability, morphology, morphometry and motility were assessed. A significant decrease in sperm function of aspartame treated animals was observed when compared with the control and MTX control. The free radical generation were observed in epididymal sperm by assessing the scavenging enzymes, enzymatic and non-enzymatic antioxidants. Result suggest that there was a significant increase glutathione-s-transferase (GST), with a significant decrease in reduced glutathione (GSH), superoxide dismutase activity (SOD), glutathione peroxidase levels (GPx), catalase activity (CAT) and glutathione reductase concentration. The increase in free radicals generation could have ultimately caused the lipid peroxidation mediated damages on the testis. Aspartame treated animals also revealed the reduced space in seminiferous tubules, which resulted in reduced Leydig cells when compared with control in histopathology. These findings demonstrate that aspartame metabolites could be a contributing factor for development of oxidative stress in the epididymal sperm.

  3. Oxidative degradation of lignin by photochemical and chemical radical generating systems

    International Nuclear Information System (INIS)

    Gold, M.H.; Kutsuki, H.; Morgan, M.A.

    1983-01-01

    Oxidation of specifically radiolabeled 14 C-lignins by UV/H 2 O 2 , Fenton's reagent, photosensitizing riboflavin, UV- and γ-irradiation was examined. In the presence of UV/H 2 O 2 , a hydroxyl radical (radicalOH) generating system, 14 C-methoxy, 2-[ 14 C-sidechain] and 14 C-ring labeled lignin were rapidly and extensively degraded as measured by gel filtration of the reaction products on Sephadex LH-20. This suggested that exposure to radicalOH leads to rapid, nonspecific lignin degradation. Rapid degradation of 14 C-methoxy, 2-[ 14 C-sidechain] and 14 C-ring labeled lignin also occurred in the presence of the radicalOH generating system, Fenton's reagent, confirming the primary role of radicalOH in these reactions. Photosensitizing riboflavin, also capable of effecting transformation of organic compounds via Type I hydrogen radical abstractions, caused extensive oxidative degradation of 14 C-methoxy labeled lignin and significant degradation of 2-[ 14 C-sidechain] and 14 C-ring labeled lignin. In addition, UV- and γ-irradiation caused slower but extensive degradation of the polymers, probably via radical type mechanisms. All of these results indicate that radicalOH as well as organic radical generating systems are effective agents for the purpose of degrading this heterogeneous, optically inactive and random biopolymer. (author)

  4. Photo-oxidative damage to isolated rat liver mitochondria induced by phenothiazines

    Directory of Open Access Journals (Sweden)

    T. RODRIGUES

    2009-01-01

    Full Text Available

    Photosensitization is a well-known side-effect of phenothiazines that could involve photochemically promoted oxidative damage to mitochondria, leading to the impairment of metabolic functions and apoptosis. In this work, for the first time, we investigated the effects of photoexcited thioridazine (TR, trifluoperazine (TFP and fluphenazine (FP on isolated rat liver mitochondria. Under UV irradiation, the presence of these phenothiazines led to a dose-dependent lack of the respiratory control ratio. These effects were not accompanied by significant swelling and oxidation of protein thiol groups but were accompanied by lipid peroxidation. Lycopene and sorbate, well-known quenchers of singlet oxygen and triplet species, respectively, were ineffective at protecting mitochondrial lipids against the damage promoted by the excited phenothiazines, suggesting that photochemically-produced cation radicals were the prooxidant species. Corroborating this proposal, butylated hydroxytoluene (BHT completely inhibited the lipid peroxidation induced by UV irradiation in the presence of phenothiazines. These novel results make a significant contribution to the understanding of the photochemical properties of phenothiazines in biological systems. Keywords: Trifluoperazine, thioridazine, fluphenazine, rat liver mitochondria, oxidative stress, photochemistry, photodamage, respiratory chain.

  5. Radical Scavenging by Acetone: A New Perspective to Understand Laccase/ABTS Inactivation and to Recover Redox Mediator.

    Science.gov (United States)

    Liu, Hao; Zhou, Pandeng; Wu, Xing; Sun, Jianliang; Chen, Shicheng

    2015-11-04

    The biosynthetic utilization of laccase/mediator system is problematic because the use of organic cosolvent causes significant inhibition of laccase activity. This work explored how the organic cosolvent impacts on the laccase catalytic capacity towards 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) in aqueous solution. Effects of acetone on the kinetic constants of laccase were determined and the results showed Km and Vmax varied exponentially with increasing acetone content. Acetone as well as some other cosolvents could transform ABTS radicals into its reductive form. The content of acetone in media significantly affected the radical scavenging rates. Up to 95% of the oxidized ABTS was successfully recovered in 80% (v/v) acetone in 60 min. This allows ABTS recycles at least six times with 70%-75% of active radicals recovered after each cycle. This solvent-based recovery strategy may help improve the economic feasibility of laccase/ABTS system in biosynthesis.

  6. A Derivative Method with Free Radical Oxidation to Predict Resveratrol Metabolites by Tandem Mass Spectrometry.

    Science.gov (United States)

    Liu, Wangta; Shiue, Yow-Ling; Lin, Yi-Reng; Lin, Hugo You-Hsien; Liang, Shih-Shin

    2015-10-01

    In this study, we demonstrated an oxidative method with free radical to generate 3,5,4'-trihydroxy- trans -stilbene ( trans -resveratrol) metabolites and detect sequentially by an autosampler coupling with liquid chromatography electrospray ionization tandem mass spectrometer (LC-ESI-MS/MS). In this oxidative method, the free radical initiator, ammonium persulfate (APS), was placed in a sample bottle containing resveratrol to produce oxidative derivatives, and the reaction progress was tracked by autosampler sequencing. Resveratrol, a natural product with purported cancer preventative qualities, produces metabolites including dihydroresveratrol, 3,4'-dihydroxy- trans -stilbene, lunularin, resveratrol monosulfate, and dihydroresveratrol monosulfate by free radical oxidation. Using APS free radical, the concentrations of resveratrol derivatives differ as a function of time. Besides simple, convenient and time- and labor saving, the advantages of free radical oxidative method of its in situ generation of oxidative derivatives followed by LC-ESI-MS/MS can be utilized to evaluate different metabolites in various conditions.

  7. Carboxylated nanodiamonds inhibit γ-irradiation damage of human red blood cells.

    Science.gov (United States)

    Santacruz-Gomez, K; Silva-Campa, E; Melendrez-Amavizca, R; Teran Arce, F; Mata-Haro, V; Landon, P B; Zhang, C; Pedroza-Montero, M; Lal, R

    2016-04-07

    Nanodiamonds when carboxylated (cNDs) act as reducing agents and hence could limit oxidative damage in biological systems. Gamma (γ)-irradiation of whole blood or its components is required in immunocompetent patients to prevent transfusion-associated graft versus host disease (TA-GVHD). However, γ-irradiation of blood also deoxygenates red blood cells (RBCs) and induces oxidative damage, including abnormalities in cellular membranes and hemolysis. Using atomic force microscopy (AFM) and Raman spectroscopy, we examined the effect of cNDs on γ-irradiation mediated deoxygenation and morphological damage of RBCs. γ-Radiation induced several morphological phenotypes, including stomatocytes, codocytes and echinocytes. While stomatocytes and codocytes are reversibly damaged RBCs, echinocytes are irreversibly damaged. AFM images show significantly fewer echinocytes among cND-treated γ-irradiated RBCs. The Raman spectra of γ-irradiated RBCs had more oxygenated hemoglobin patterns when cND-treated, resembling those of normal, non-irradiated RBCs, compared to the non-cND-treated RBCs. cND inhibited hemoglobin deoxygenation and morphological damage, possibly by neutralizing the free radicals generated during γ-irradiation. Thus cNDs have the therapeutic potential to preserve the quality of stored blood following γ-irradiation.

  8. Photolysis and oxidation of azidophenyl-substituted radicals: delocalization in heteroatom-based radicals.

    Science.gov (United States)

    Serwinski, Paul R; Esat, Burak; Lahti, Paul M; Liao, Yi; Walton, Richard; Lan, Jiang

    2004-08-06

    2-(4-Azidophenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (14), 2-(4-azidophenyl)benzimidazole-1-oxide-3-oxyl (16), 2-(4-azidophenyl)-1,2,6-triphenylverdazyl (19), 2-(3-azidophenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl (21), and (3-azidophenyl)-N-tert-butyl-N-aminoxyl (25) were photolyzed in frozen solution to give S = 3/2 state ESR spectra of the corresponding nitrenophenyl radicals with the following zero-field splitting parameters: |D/hc| = 0.277 cm(-1), |E/hc| ions were unsuccessful: Cu(ClO4)2 x 6H2O instead oxidized them to the corresponding diamagnetic nitrosonium perchlorate salts. Copyright 2004 American Chemical Society

  9. Attenuation of Oxidative Damage by Boerhaavia diffusa L. Against Different Neurotoxic Agents in Rat Brain Homogenate.

    Science.gov (United States)

    Ayyappan, Prathapan; Palayyan, Salin Raj; Kozhiparambil Gopalan, Raghu

    2016-01-01

    Due to a high rate of oxidative metabolic activity in the brain, intense production of reactive oxygen metabolite occurs, and the subsequent generation of free radicals is implicated in the pathogenesis of traumatic brain injury, epilepsy, and ischemia as well as chronic neurodegenerative diseases. In the present study, protective effects of polyphenol rich ethanolic extract of Boerhaavia diffusa (BDE), a neuroprotective edible medicinal plant against oxidative stress induced by different neurotoxic agents, were evaluated. BDE was tested against quinolinic acid (QA), 3-nitropropionic acid (NPA), sodium nitroprusside (SNP), and Fe (II)/EDTA complex induced oxidative stress in rat brain homogenates. QA, NPA, SNP, and Fe (II)/EDTA treatment caused an increased level of thiobarbituric acid reactive substances (TBARS) in brain homogenates along with a decline in the activities of antioxidant enzymes. BDE treatment significantly decreased the production of TBARS (p cerebral cortex. Inhibitory potential of BDE against deoxyribose degradation (IC50 value 38.91 ± 0.12 μg/ml) shows that BDE can protect hydroxyl radical induced DNA damage in the tissues. Therefore, B. diffusa had high antioxidant potential that could inhibit the oxidative stress induced by different neurotoxic agents in brain. Since many of the neurological disorders are associated with free radical injury, these data may imply that B. diffusa, functioning as an antioxidant agent, may be beneficial for reducing various neurodegenerative complications.

  10. Oxidative DNA damage and oxidative stress in lead-exposed workers.

    Science.gov (United States)

    Dobrakowski, M; Pawlas, N; Kasperczyk, A; Kozłowska, A; Olewińska, E; Machoń-Grecka, A; Kasperczyk, S

    2017-07-01

    There are many discrepancies among the results of studies on the genotoxicity of lead. The aim of the study was to explore lead-induced DNA damage, including oxidative damage, in relation to oxidative stress intensity parameters and the antioxidant defense system in human leukocytes. The study population consisted of 100 male workers exposed to lead. According to the blood lead (PbB) levels, they were divided into the following three subgroups: a group with PbB of 20-35 μg/dL (low exposure to lead (LE) group), a group with a PbB of 35-50 µg/dL (medium exposure to lead (ME) group), and a group with a PbB of >50 μg/dL (high exposure to lead (HE) group). The control group consisted of 42 healthy males environmentally exposed to lead (PbB lead exposure induces DNA damage, including oxidative damage, in human leukocytes. The increase in DNA damage was accompanied by an elevated intensity of oxidative stress.

  11. Anticancer system created by acrolein and hydroxyl radical generated in enzymatic oxidation of spermine and other biochemical reactions.

    Science.gov (United States)

    Alarcon, R A

    2012-10-01

    A hypothesis suggesting the existence of a ubiquitous physiological anticancer system created by two highly reactive oxidative stress inducers with anticancer properties, acrolein and hydroxyl radical, is reported in this communication. Both components can originate separately or together in several biochemical interactions, among them, the enzymatic oxidation of the polyamine spermine, which appear to be their main source. The foundations of this hypothesis encompass our initial search for growth-inhibitors or anticancer compounds in biological material leading to the isolation of spermine, a polyamine that became highly cytotoxic through the generation of acrolein, when enzymatically oxidized. Findings complemented with pertinent literature data by other workers and observed anticancer activities by sources capable of producing acrolein and hydroxyl radical. This hypothesis obvious implication: spermine enzymatic oxidations or other biochemical interactions that would co-generate acrolein and hydroxyl radical, the anticancer system components, should be tried as treatments for any given cancer. The biochemical generation of acrolein observed was totally unexpected, since this aldehyde was known; as a very toxic and highly reactive xenobiotic chemical produced in the pyrolysis of fats and other organic material, found as an atmospheric pollutant, in tobacco smoke and car emissions, and mainly used as a pesticide or aquatic herbicide. Numerous studies on acrolein, considered after our work a biological product, as well, followed. In them, acrolein widespread presence, its effects on diverse cellular proteins, such as, growth factors, and its anticancer activities, were additionally reported. Regarding hydroxyl radical, the second component of the proposed anticancer system, and another cytotoxic product in normal cell metabolism, it co-generates with acrolein in several biochemical interactions, occurrences suggesting that these products might jointly fulfill some

  12. Assessment of the Antioxidant Activity of Silybum marianum Seed Extract and Its Protective Effect against DNA Oxidation, Protein Damage and Lipid Peroxidation

    Directory of Open Access Journals (Sweden)

    Aynur Serçe

    2016-01-01

    Full Text Available Antioxidant properties of ethanol extract of Silybum marianum (milk thistle seeds was investigated. We have also investigated the protein damage activated by oxidative Fenton reaction and its prevention by Silybum marianum seed extract. Antioxidant potential of Silybum marianum seed ethanol extract was measured using diff erent in vitro methods, such as lipid peroxidation, 1,1–diphenyl–2–picrylhydrazyl (DPPH and ferric reducing power assays. The extract significantly decreased DNA damage caused by hydroxyl radicals. Protein damage induced by hydroxyl radicals was also effi ciently inhibited, which was confirmed by the presence of protein damage markers, such as protein carbonyl formation and by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS–PAGE. The present study shows that milk thistle seeds have good DPPH free radical scavenging activity and can prevent lipid peroxidation. Therefore, Silybum marianum can be used as potentially rich source of antioxidants and food preservatives. The results suggest that the seeds may have potential beneficial health effects providing opportunities to develop value-added products.

  13. Oxidation of DNA, proteins and lipids by DOPA, protein-bound DOPA, and related catechol(amine)s

    DEFF Research Database (Denmark)

    Pattison, David I; Dean, Roger T; Davies, Michael Jonathan

    2002-01-01

    Incubation of free 3,4-dihydroxyphenylalanine (DOPA), protein-bound DOPA (PB-DOPA) and related catechols with DNA, proteins and lipids has been shown to result in oxidative damage to the target molecule. This article reviews these reactions with particular emphasis on those that occur in the pres......Incubation of free 3,4-dihydroxyphenylalanine (DOPA), protein-bound DOPA (PB-DOPA) and related catechols with DNA, proteins and lipids has been shown to result in oxidative damage to the target molecule. This article reviews these reactions with particular emphasis on those that occur...... in the presence of molecular O(2) and redox-active metal ions (e.g. Fe(3+), Cu(2+), Cr(6+)), which are known to increase the rate of DOPA oxidation. The majority of oxidative damage appears to be mediated by reactive oxygen species (ROS) such as superoxide and HO(.) radicals, though other DOPA oxidation products...

  14. Oxidative stress mediated mitochondrial and vascular lesions as markers in the pathogenesis of Alzheimer disease.

    Science.gov (United States)

    Aliev, G; Priyadarshini, M; Reddy, V P; Grieg, N H; Kaminsky, Y; Cacabelos, R; Ashraf, G Md; Jabir, N R; Kamal, M A; Nikolenko, V N; Zamyatnin, A A; Benberin, V V; Bachurin, S O

    2014-01-01

    Mitochondrial dysfunction plausibly underlies the aging-associated brain degeneration. Mitochondria play a pivotal role in cellular bioenergetics and cell-survival. Oxidative stress consequent to chronic hypoperfusion induces mitochondrial damage, which is implicated as the primary cause of cerebrovascular accidents (CVA) mediated Alzheimer's disease (AD). The mitochondrial function deteriorates with aging, and the mitochondrial damage correlates with increased intracellular production of oxidants and pro-oxidants. The prolonged oxidative stress and the resultant hypoperfusion in the brain tissues stimulate the expression of nitric oxide synthase (NOS) enzymes, which further drives the formation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). The ROS and RNS collectively contributes to the dysfunction of the blood-brain barrier (BBB) and damage to the brain parenchymal cells. Delineating the molecular mechanisms of these processes may provide clues for the novel therapeutic targets for CVA and AD patients.

  15. Atmospherically Relevant Radicals Derived from the Oxidation of Dimethyl Sulfide.

    Science.gov (United States)

    Mardyukov, Artur; Schreiner, Peter R

    2018-02-20

    The large number and amounts of volatile organosulfur compounds emitted to the atmosphere and the enormous variety of their reactions in various oxidation states make experimental measurements of even a small fraction of them a daunting task. Dimethyl sulfide (DMS) is a product of biological processes involving marine phytoplankton, and it is estimated to account for approximately 60% of the total natural sulfur gases released to the atmosphere. Ocean-emitted DMS has been suggested to play a role in atmospheric aerosol formation and thereby cloud formation. The reaction of ·OH with DMS is known to proceed by two independent channels: abstraction and addition. The oxidation of DMS is believed to be initiated by the reaction with ·OH and NO 3 · radicals, which eventually leads to the formation of sulfuric acid (H 2 SO 4 ) and methanesulfonic acid (CH 3 SO 3 H). The reaction of DMS with NO 3 · appears to proceed exclusively by hydrogen abstraction. The oxidation of DMS consists of a complex sequence of reactions. Depending on the time of the day or altitude, it may take a variety of pathways. In general, however, the oxidation proceeds via chains of radical reactions. Dimethyl sulfoxide (DMSO) has been reported to be a major product of the addition channel. Dimethyl sulfone (DMSO 2 ), SO 2 , CH 3 SO 3 H, and methanesulfinic acid (CH 3 S(O)OH) have been observed as products of further oxidation of DMSO. Understanding the details of DMS oxidation requires in-depth knowledge of the elementary steps of this seemingly simple transformation, which in turn requires a combination of experimental and theoretical methods. The methylthiyl (CH 3 S·), methylsulfinyl (CH 3 SO·), methylsulfonyl (CH 3 SO 2 ·), and methylsulfonyloxyl (CH 3 SO 3 ·) radicals have been postulated as intermediates in the oxidation of DMS. Therefore, studying the chemistry of sulfur-containing free radicals in the laboratory also is the basis for understanding the mechanism of DMS oxidation in the

  16. Oxidative stress and proinflammatory cytokines contribute to demyelination and axonal damage in a cerebellar culture model of neuroinflammation.

    Science.gov (United States)

    di Penta, Alessandra; Moreno, Beatriz; Reix, Stephanie; Fernandez-Diez, Begoña; Villanueva, Maite; Errea, Oihana; Escala, Nagore; Vandenbroeck, Koen; Comella, Joan X; Villoslada, Pablo

    2013-01-01

    Demyelination and axonal damage are critical processes in the pathogenesis of multiple sclerosis (MS). Oxidative stress and pro-inflammatory cytokines elicited by inflammation mediates tissue damage. To monitor the demyelination and axonal injury associated with microglia activation we employed a model using cerebellar organotypic cultures stimulated with lipopolysaccharide (LPS). Microglia activated by LPS released pro-inflammatory cytokines (IL-1β, IL-6 and TNFα), and increased the expression of inducible nitric oxide synthase (iNOS) and production of reactive oxygen species (ROS). This activation was associated with demyelination and axonal damage in cerebellar cultures. Axonal damage, as revealed by the presence of non-phosphorylated neurofilaments, mitochondrial accumulation in axonal spheroids, and axonal transection, was associated with stronger iNOS expression and concomitant increases in ROS. Moreover, we analyzed the contribution of pro-inflammatory cytokines and oxidative stress in demyelination and axonal degeneration using the iNOS inhibitor ethyl pyruvate, a free-scavenger and xanthine oxidase inhibitor allopurinol, as well as via blockage of pro-inflammatory cytokines using a Fc-TNFR1 construct. We found that blocking microglia activation with ethyl pyruvate or allopurinol significantly decreased axonal damage, and to a lesser extent, demyelination. Blocking TNFα significantly decreased demyelination but did not prevented axonal damage. Moreover, the most common therapy for MS, interferon-beta, was used as an example of an immunomodulator compound that can be tested in this model. In vitro, interferon-beta treatment decreased oxidative stress (iNOS and ROS levels) and the release of pro-inflammatory cytokines after LPS stimulation, reducing axonal damage. The model of neuroinflammation using cerebellar culture stimulated with endotoxin mimicked myelin and axonal damage mediated by the combination of oxidative stress and pro-inflammatory cytokines

  17. Evidence of free radical and antioxidant activity in Spirodela exposed to metallic and metal oxide nanoparticles: potential for protein and lipid damage

    CSIR Research Space (South Africa)

    Thwala, Melusi

    2012-04-01

    Full Text Available the quantities of free radicals (H202, total ROS/RNS), antioxidant activity (catalase, superoxide disrnutasc, and total antioxidam capacity) were analyzed. Oxidative stress has been suggested as a significant route of toxicity induction by engineered...

  18. Hypoxia-ischemia and retinal ganglion cell damage

    Directory of Open Access Journals (Sweden)

    Charanjit Kaur

    2008-08-01

    Full Text Available Charanjit Kaur1, Wallace S Foulds2, Eng-Ang Ling11Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; 2Singapore Eye Research Institute, SingaporeAbstract: Retinal hypoxia is the potentially blinding mechanism underlying a number of sight-threatening disorders including central retinal artery occlusion, ischemic central retinal vein thrombosis, complications of diabetic eye disease and some types of glaucoma. Hypoxia is implicated in loss of retinal ganglion cells (RGCs occurring in such conditions. RGC death occurs by apoptosis or necrosis. Hypoxia-ischemia induces the expression of hypoxia inducible factor-1α and its target genes such as vascular endothelial growth factor (VEGF and nitric oxide synthase (NOS. Increased production of VEGF results in disruption of the blood retinal barrier leading to retinal edema. Enhanced expression of NOS results in increased production of nitric oxide which may be toxic to the cells resulting in their death. Excess glutamate release in hypoxic-ischemic conditions causes excitotoxic damage to the RGCs through activation of ionotropic and metabotropic glutamate receptors. Activation of glutamate receptors is thought to initiate damage in the retina by a cascade of biochemical effects such as neuronal NOS activation and increase in intracellular Ca2+ which has been described as a major contributing factor to RGC loss. Excess production of proinflammatory cytokines also mediates cell damage. Besides the above, free-radicals generated in hypoxic-ischemic conditions result in RGC loss because of an imbalance between antioxidant- and oxidant-generating systems. Although many advances have been made in understanding the mediators and mechanisms of injury, strategies to improve the damage are lacking. Measures to prevent neuronal injury have to be developed.Keywords: retinal hypoxia, retinal ganglion cells, glutamate receptors, neuronal injury, retina

  19. Effect of Rubia cordifolia, Fagonia cretica linn, and Tinospora cordifolia on free radical generation and lipid peroxidation during oxygen-glucose deprivation in rat hippocampal slices

    International Nuclear Information System (INIS)

    Rawal, Avinash; Muddeshwar, Manohar; Biswas, Saibal

    2004-01-01

    The major damaging factor during and after the ischemic/hypoxic insult is the generation of free radicals, which leads to apoptosis, necrosis, and ultimately cell death. Rubia cordifolia (RC), Fagonia cretica linn (FC), and Tinospora cordifolia (TC) have been reported to contain a wide variety of antioxidants and have been in use in the eastern system of medicine for various disorders. Hippocampal slices were subjected to oxygen-glucose deprivation (OGD) and divided into three groups, control, OGD, and OGD+drug treated. Cytosolic reduced glutathione (GSH), nitric oxide [NO, measured as nitrite (NO 2 )]. EPR was used to establish the antioxidant effect of RC, FC, and TC with respect to superoxide anion (O2-), hydroxyl radicals (OH), nitric oxide (NO) radical, and peroxynitrite anion (ONOO - ) generated from pyrogallol, menadione, DETA-NO, and Sin-1, respectively. RT-PCR was performed for the three herbs to assess their effect on the expression of γ-glutamylcysteine ligase (GCLC), iNOS, and GAPDH gene expression. All the three herbs were effective in elevating the GSH levels and expression of the GCLC. The herbs also exhibited strong free radical scavenging properties against reactive oxygen and nitrogen species as revealed by electron paramagnetic resonance spectroscopy, diminishing the expression of iNOS gene. RC, FC, and TC therefore attenuate oxidative stress mediated cell injury during OGD and exert the above effects at both the cytosolic as well as at gene expression levels and may be effective therapeutic tool against ischemic brain damage

  20. Fisetin Protects DNA Against Oxidative Damage and Its Possible Mechanism.

    Science.gov (United States)

    Wang, Tingting; Lin, Huajuan; Tu, Qian; Liu, Jingjing; Li, Xican

    2016-06-01

    The paper tries to assess the protective effect of fisetin against •OH-induced DNA damage, then to investigate the possible mechanism. The protective effect was evaluated based on the content of malondialdehyde (MDA). The possible mechanism was analyzed using various antioxidant methods in vitro, including •OH scavenging (deoxyribose degradation), •O2 (-) scavenging (pyrogallol autoxidation), DPPH• scavenging, ABTS•(+) scavenging, and Cu(2+)-reducing power assays. Fisetin increased dose-dependently its protective percentages against •OH-induced DNA damage (IC50 value =1535.00±29.60 µM). It also increased its radical-scavenging percentages in a dose-dependent manner in various antioxidants assays. Its IC50 values in •OH scavenging, •O2(-) scavenging, DPPH• scavenging, ABTS•(+) scavenging, and Cu(2+)-reducing power assays, were 47.41±4.50 µM, 34.05±0.87 µM, 9.69±0.53 µM, 2.43±0.14 µM, and 1.49±0.16 µM, respectively. Fisetin can effectively protect DNA against •OH-induced oxidative damage possibly via reactive oxygen species (ROS) scavenging approach, which is assumed to be hydrogen atom (H•) and/or single electron (e) donation (HAT/SET) pathways. In the HAT pathway, the 3',4'-dihydroxyl moiety in B ring of fisetin is thought to play an important role, because it can be ultimately oxidized to a stable ortho-benzoquinone form.

  1. Kinetic determinations of accurate relative oxidation potentials of amines with reactive radical cations.

    Science.gov (United States)

    Gould, Ian R; Wosinska, Zofia M; Farid, Samir

    2006-01-01

    Accurate oxidation potentials for organic compounds are critical for the evaluation of thermodynamic and kinetic properties of their radical cations. Except when using a specialized apparatus, electrochemical oxidation of molecules with reactive radical cations is usually an irreversible process, providing peak potentials, E(p), rather than thermodynamically meaningful oxidation potentials, E(ox). In a previous study on amines with radical cations that underwent rapid decarboxylation, we estimated E(ox) by correcting the E(p) from cyclic voltammetry with rate constants for decarboxylation obtained using laser flash photolysis. Here we use redox equilibration experiments to determine accurate relative oxidation potentials for the same amines. We also describe an extension of these experiments to show how relative oxidation potentials can be obtained in the absence of equilibrium, from a complete kinetic analysis of the reversible redox kinetics. The results provide support for the previous cyclic voltammetry/laser flash photolysis method for determining oxidation potentials.

  2. Glutathione as a radical scavenger and the biological consequences of thiyl radical production

    International Nuclear Information System (INIS)

    Winterbourn, C.C.

    1996-01-01

    A large number of compounds that have toxic effects can be metabolised to free radicals and secondary reactive oxygen species. These may be directly damaging or affect cell function by altering regulatory mechanisms through changing redox status. Protection is provided by an integrated system of antioxidant defenses. This includes reduced glutathione (GSH), one of the functions of which is as a free radical scavenger. For GSH to be an effective radical scavenging antioxidant, therefore, it must act in concert with superoxide dismutase to remove the superoxide so generated. Superoxide is produced in a variety of metabolic processes. It is also a secondary product of radicals reacting with oxygen either directly or through GSH. The biological reactivity of superoxide has been the subject of much debate ever since the discovery of superoxide dismutase in 1968. It has more recently become apparent that its rapid reaction with nitric oxide to give peroxynitrite, and its ability to reversibly oxidise and inactivate iron sulphur enzymes, contribute to the toxicity of superoxide. Another mechanism that could be important involves addition reactions of superoxide with other radicals to give organic peroxides. This reaction, to form a tyrosine peroxide, has come to authors attention through the study of the scavenging of tyrosyl radicals by GSH. It is also shown that a tyrosine peroxide is a major product of the oxidation of tyrosine by neutrophils

  3. Degradation of lipid regulators by the UV/chlorine process: Radical mechanisms, chlorine oxide radical (ClO•)-mediated transformation pathways and toxicity changes.

    Science.gov (United States)

    Kong, Xiujuan; Wu, Zihao; Ren, Ziran; Guo, Kaiheng; Hou, Shaodong; Hua, Zhechao; Li, Xuchun; Fang, Jingyun

    2018-06-15

    Degradation of three lipid regulators, i.e., gemfibrozil, bezafibrate and clofibric acid, by a UV/chlorine treatment was systematically investigated. The chlorine oxide radical (ClO • ) played an important role in the degradation of gemfibrozil and bezafibrate with second-order rate constants of 4.2 (±0.3) × 10 8  M -1  s -1 and 3.6 (±0.1) × 10 7  M -1  s -1 , respectively, whereas UV photolysis and the hydroxyl radical (HO • ) mainly contributed to the degradation of clofibric acid. The first-order rate constants (k') for the degradation of gemfibrozil and bezafibrate increased linearly with increasing chlorine dosage, primarily due to the linear increase in the ClO • concentration. The k' values for gemfibrozil, bezafibrate, and clofibric acid degradation decreased with increasing pH from 5.0 to 8.4; however, the contribution of the reactive chlorine species (RCS) increased. Degradation of gemfibrozil and bezafibrate was enhanced in the presence of Br - , whereas it was inhibited in the presence of natural organic matter (NOM). The presence of ammonia at a chlorine: ammonia molar ratio of 1:1 resulted in decreases in the k' values for gemfibrozil and bezafibrate of 69.7% and 7%, respectively, but led to an increase in that for clofibric acid of 61.8%. Degradation of gemfibrozil by ClO • was initiated by hydroxylation and chlorine substitution on the benzene ring. Then, subsequent hydroxylation, bond cleavage and chlorination reactions led to the formation of more stable products. Three chlorinated intermediates were identified during ClO • oxidation process. Formation of the chlorinated disinfection by-products chloral hydrate and 1,1,1-trichloropropanone was enhanced relative to that of other by-products. The acute toxicity of gemfibrozil to Vibrio fischeri increased significantly when subjected to direct UV photolysis, whereas it decreased when oxidized by ClO • . This study is the first to report the transformation pathway of a

  4. Oxidation of alpha-tocopherol in micelles and liposomes by the hydroxyl, perhydroxyl, and superoxide free radicals

    International Nuclear Information System (INIS)

    Fukuzawa, K.; Gebicki, J.M.

    1983-01-01

    Rates of oxidation of alpha-tocopherol by the hydroxyl- and superoxide free radicals were measured. The radicals were produced in known yields by radiolysis of aqueous solutions with gamma rays. Two main systems were used to dissolve the tocopherol; micelles, made up from charged and uncharged amphiphiles, and membranes made from dimyristyl phosphatidylcholine which could be charged by addition of stearyl amine or dicetyl phosphate. The HO. radicals were efficient oxidants of alpha-tocopherol in all systems, with up to 83% of radicals generated in micelle and 32% in membrane suspensions initiating the oxidation. The HO 2 radical was an even more effective oxidant, but when most of it was in the O 2 form at neutral or alkaline pH, the oxidation rates became low. Tocopherol held in positively charged micelles or membranes was oxidized at a higher rate by the O 2 than in uncharged or negative particles. Possible biological significance of these results is discussed

  5. Oxidation of aromatic amines and diamines by OH radicals. Formation and ionization constants of amine cation radicals in water

    International Nuclear Information System (INIS)

    Hayon, E.; Rao, P.S.

    1975-01-01

    The one-electron oxidation by hydroxyl radicals of aromatic amines and diamines in water was studied using the fast-reaction technique of pulse radiolysis and kinetic absorption spectrophotometry. The following compounds were examined: N,N,N 1 ,N 1 - tetramethyl-p-phenylenediamine (TMPD), p-phenylenediamine (PD), N,N-dimethyl-p-phenylenediamene (DMPD), N,N,N 1 ,N 1 -tetramethylbenzidine (TMB), and diphenylamine (DPA). The main initial reaction of the OH radicals is suggested to be an addition to these compounds to give absorption spectra which absorb strongly in the visible and uv regions. These OH radical adducts decay by first-order kinetics and have lifetimes of approximately 5-50 μsec, dependent on the pH, buffer concentration, and the nature of the aromatic amines and diamines. They decay to give species with somewhat similar absorption spectra and extinction coefficients, which are very long lived in the absence of oxygen. The latter species are assigned to the cation radicals TMPD. + , PD. + , DMPD. + , TMB. + , and DPA. + . The OH radical adducts and the cation radicals have acid-base properties. The pK/sub a/ values of the cation radicals TMPDH. 2+ , PDH. 2+ , DMPDH. 2+ , TMBH. 2+ , and DPAH. 2+ were found to be 5.3, 5.9, 6.1, 5.1, and 4.2, respectively. The results indicate that these aromatic amines and diamines can be oxidized by free radicals to yield the corresponding cation radicals. (U.S.)

  6. Oxidation of spin-traps by chlorine dioxide (ClO2) radical in aqueous solutions: first ESR evidence of formation of new nitroxide radicals.

    Science.gov (United States)

    Ozawa, T; Miura, Y; Ueda, J

    1996-01-01

    The reactivities of the chlorine dioxide (ClO2), which is a stable free radical towards some water-soluble spin-traps were investigated in aqueous solutions by an electron spin resonance (ESR) spectroscopy. The ClO2 radical was generated from the redox reaction of Ti3+ with potassium chlorate (KClO3) in aqueous solutions. When one of the spin-traps, 5,5-dimethyl-1-pyrroline N-oxide (DMPO), was included in the Ti3+-KClO3 reaction system, ESR spectrum due to the ClO2 radical completely disappeared and a new ESR spectrum [aN(1) = 0.72 mT, aH(2) = 0.41 mT], which is different from that of DMPO-ClO2 adduct, was observed. The ESR parameters of this new ESR signal was identical to those of 5,5-dimethylpyrrolidone-(2)-oxyl-(1) (DMPOX), suggesting the radical species giving the new ESR spectrum is assignable to DMPOX. The similar ESR spectrum consisting of a triplet [aN(1) = 0.69 mT] was observed when the derivative of DMPO, 3,3,5,5-tetramethyl-1-pyrroline N-oxide (M4PO) was included in the Ti3+-KClO3 reaction system. This radical species is attributed to the oxidation product of M4PO, 3,3,5,5-tetramethylpyrrolidone-(2)-oxyl-(1) (M4POX). When another nitrone spin-trap, alpha-(4-pyridyl-1-oxide)-N-t-butylnitrone (POBN) was used as a spin-trap, the ESR signal intensity due to the ClO2 radical decreased and a new ESR signal consisting of a triplet [aN(1) = 0.76 mT] was observed. The similar ESR spectrum was observed when N-t-butyl-alpha- nitrone (PBN) was used as a spin-trap. This ESR parameter [a(N)(1) = 0.85 mT] was identical to the oxidation product of PBN, PBNX. Thus, the new ESR signal observed from POBN may be assigned to the oxidation product of POBN, POBNX. These results suggest that the ClO2, radical does not form the stable spin adducts with nitrone spin-traps, but oxidizes these spin-traps to give the corresponding nitroxyl radicals. On the other hand, nitroso spin-traps, 5,5-dibromo-4-nitrosobenzenesulfonate (DBNBS), and 2-methyl-2-nitrosopropane (MNP) did not trap

  7. Oxidative stress and the evolution of sex differences in life span and ageing in the decorated cricket, Gryllodes sigillatus.

    Science.gov (United States)

    Archer, Catharine R; Sakaluk, Scott K; Selman, Colin; Royle, Nick J; Hunt, John

    2013-03-01

    The Free Radical Theory of Ageing (FRTA) predicts that oxidative stress, induced when levels of reactive oxygen species exceed the capacity of antioxidant defenses, causes ageing. Recently, it has also been argued that oxidative damage may mediate important life-history trade-offs. Here, we use inbred lines of the decorated cricket, Gryllodes sigillatus, to estimate the genetic (co)variance between age-dependent reproductive effort, life span, ageing, oxidative damage, and total antioxidant capacity within and between the sexes. The FRTA predicts that oxidative damage should accumulate with age and negatively correlate with life span. We find that protein oxidation is greater in the shorter lived sex (females) and negatively genetically correlated with life span in both sexes. However, oxidative damage did not accumulate with age in either sex. Previously we have shown antagonistic pleiotropy between the genes for early-life reproductive effort and ageing rate in both sexes, although this was stronger in females. In females, we find that elevated fecundity early in life is associated with greater protein oxidation later in life, which is in turn positively correlated with the rate of ageing. Our results provide mixed support for the FRTA but suggest that oxidative stress may mediate sex-specific life-history strategies in G. sigillatus. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.

  8. SULFATE RADICAL-BASED ADVANCED OXIDATION PROCESSES- ACS MEETING

    Science.gov (United States)

    This paper will present an overview of sulfate radical-based advanced oxidation technologies for the destruction of environmentally toxic chemicals in wastewater, industrial water, groundwater and sources of water supply. The paper will include fundamental aspects of the generati...

  9. Polydatin attenuates d-galactose-induced liver and brain damage through its anti-oxidative, anti-inflammatory and anti-apoptotic effects in mice.

    Science.gov (United States)

    Xu, Lie-Qiang; Xie, You-Liang; Gui, Shu-Hua; Zhang, Xie; Mo, Zhi-Zhun; Sun, Chao-Yue; Li, Cai-Lan; Luo, Dan-Dan; Zhang, Zhen-Biao; Su, Zi-Ren; Xie, Jian-Hui

    2016-11-09

    Accumulating evidence has shown that chronic injection of d-galactose (d-gal) can mimic natural aging, with accompanying liver and brain injury. Oxidative stress and apoptosis play a vital role in the aging process. In this study, the antioxidant ability of polydatin (PD) was investigated using four established in vitro systems. An in vivo study was also conducted to investigate the possible protective effect of PD on d-gal-induced liver and brain damage. The results showed that PD had remarkable in vitro free radical scavenging activity on 2,2-diphenyl-1-picryl-hydrazyl (DPPH˙), 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) (ABTS + ˙) radical ions, and hydroxyl and superoxide anions. Results in vivo indicated that, in a group treated with d-gal plus PD, PD remarkably decreased the depression of body weight and organ indexes, reduced the levels of the serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and alleviated alterations in liver and brain histopathology. PD also significantly decreased the level of MDA and elevated SOD, GSH-Px, CAT activity and T-AOC levels in the liver and brain. In addition, the levels of inflammatory mediators, such as TNF-α, IL-1β and IL-6 in serum were markedly reduced after PD treatment. Western blotting results revealed that PD treatment noticeably attenuated the d-gal-induced elevation of Bcl-2/Bax ratio and caspase-3 protein expression in liver and brain. Overall, our findings indicate that PD treatment could effectively attenuate d-gal-induced liver and brain damage, and the mechanism might be associated with decreasing the oxidative stress, inflammation and apoptosis caused by d-gal. PD holds good potential for further development into a promising pharmaceutical candidate for the treatment of age-associated diseases.

  10. Predicting storage-dependent damage to red blood cells using nitrite oxidation kinetics, peroxiredoxin-2 oxidation, and hemoglobin and free heme measurements.

    Science.gov (United States)

    Oh, Joo-Yeun; Stapley, Ryan; Harper, Victoria; Marques, Marisa B; Patel, Rakesh P

    2015-12-01

    Storage-dependent damage to red blood cells (RBCs) varies significantly. Identifying RBC units that will undergo higher levels of hemolysis during storage may allow for more efficient inventory management decision-making. Oxidative-stress mediates storage-dependent damage to RBCs and will depend on the oxidant:antioxidant balance. We reasoned that this balance or redox tone will serve as a determinant of how a given RBC unit stores and that its assessment in "young" RBCs will predict storage-dependent hemolysis. RBCs were sampled from bags and segments stored for 7 to 42 days. Redox tone was assessed by nitrite oxidation kinetics and peroxiredoxin-2 (Prx-2) oxidation. In parallel, hemolysis was assessed by measuring cell-free hemoglobin (Hb) and free heme (hemin). Correlation analyses were performed to determine if Day 7 measurements predicted either the level of hemolysis at Day 35 or the increase in hemolysis during storage. Higher Day 7 Prx-2 oxidation was associated with higher Day 35 Prx-2 oxidation, suggesting that early assessment of this variable may identify RBCs that will incur the most oxidative damage during storage. RBCs that oxidized nitrite faster on Day 7 were associated with the greatest levels of storage-dependent hemolysis and increases in Prx-2 oxidation. An inverse relationship between storage-dependent changes in oxyhemoglobin and free heme was observed underscoring an unappreciated reciprocity between these molecular species. Moreover, free heme was higher in the bag compared to paired segments, with opposite trends observed for free Hb. Measurement of Prx-2 oxidation and nitrite oxidation kinetics early during RBC storage may predict storage-dependent damage to RBC including hemolysis-dependent formation of free Hb and heme. © 2015 AABB.

  11. Inflammation, gene mutation and photoimmunosuppression in response to UVR-induced oxidative damage contributes to photocarcinogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Halliday, Gary M. [Dermatology Research Laboratories, Division of Medicine, Melanoma and Skin Cancer Research Institute, Royal Prince Alfred Hospital at the University of Sydney, Sydney, NSW (Australia)]. E-mail: garyh@med.usyd.edu.au

    2005-04-01

    Ultraviolet (UV) radiation causes inflammation, gene mutation and immunosuppression in the skin. These biological changes are responsible for photocarcinogenesis. UV radiation in sunlight is divided into two wavebands, UVB and UVA, both of which contribute to these biological changes, and therefore probably to skin cancer in humans and animal models. Oxidative damage caused by UV contributes to inflammation, gene mutation and immunosuppression. This article reviews evidence for the hypothesis that UV oxidative damage to these processes contributes to photocarcinogenesis. UVA makes a larger impact on oxidative stress in the skin than UVB by inducing reactive oxygen and nitrogen species which damage DNA, protein and lipids and which also lead to NAD+ depletion, and therefore energy loss from the cell. Lipid peroxidation induces prostaglandin production that in association with UV-induced nitric oxide production causes inflammation. Inflammation drives benign human solar keratosis (SK) to undergo malignant conversion into squamous cell carcinoma (SCC) probably because the inflammatory cells produce reactive oxygen species, thus increasing oxidative damage to DNA and the immune system. Reactive oxygen or nitrogen appears to cause the increase in mutational burden as SK progress into SCC in humans. UVA is particularly important in causing immunosuppression in both humans and mice, and UV lipid peroxidation induced prostaglandin production and UV activation of nitric oxide synthase is important mediators of this event. Other immunosuppressive events are likely to be initiated by UV oxidative stress. Antioxidants have also been shown to reduce photocarcinogenesis. While most of this evidence comes from studies in mice, there is supporting evidence in humans that UV-induced oxidative damage contributes to inflammation, gene mutation and immunosuppression. Available evidence implicates oxidative damage as an important contributor to sunlight-induced carcinogenesis in humans.

  12. Inflammation, gene mutation and photoimmunosuppression in response to UVR-induced oxidative damage contributes to photocarcinogenesis

    International Nuclear Information System (INIS)

    Halliday, Gary M.

    2005-01-01

    Ultraviolet (UV) radiation causes inflammation, gene mutation and immunosuppression in the skin. These biological changes are responsible for photocarcinogenesis. UV radiation in sunlight is divided into two wavebands, UVB and UVA, both of which contribute to these biological changes, and therefore probably to skin cancer in humans and animal models. Oxidative damage caused by UV contributes to inflammation, gene mutation and immunosuppression. This article reviews evidence for the hypothesis that UV oxidative damage to these processes contributes to photocarcinogenesis. UVA makes a larger impact on oxidative stress in the skin than UVB by inducing reactive oxygen and nitrogen species which damage DNA, protein and lipids and which also lead to NAD+ depletion, and therefore energy loss from the cell. Lipid peroxidation induces prostaglandin production that in association with UV-induced nitric oxide production causes inflammation. Inflammation drives benign human solar keratosis (SK) to undergo malignant conversion into squamous cell carcinoma (SCC) probably because the inflammatory cells produce reactive oxygen species, thus increasing oxidative damage to DNA and the immune system. Reactive oxygen or nitrogen appears to cause the increase in mutational burden as SK progress into SCC in humans. UVA is particularly important in causing immunosuppression in both humans and mice, and UV lipid peroxidation induced prostaglandin production and UV activation of nitric oxide synthase is important mediators of this event. Other immunosuppressive events are likely to be initiated by UV oxidative stress. Antioxidants have also been shown to reduce photocarcinogenesis. While most of this evidence comes from studies in mice, there is supporting evidence in humans that UV-induced oxidative damage contributes to inflammation, gene mutation and immunosuppression. Available evidence implicates oxidative damage as an important contributor to sunlight-induced carcinogenesis in humans

  13. Effect of hydromorphone hydrochloride combined with ropivacaine for PCEA after orthopedic surgery on the synthesis of pain mediators, inflammatory mediator and oxygen free radicals

    Directory of Open Access Journals (Sweden)

    Liang-Ying Luo

    2017-08-01

    Full Text Available Objective: To explore the effect of hydromorphone hydrochloride combined with ropivacaine for PCEA after orthopedic surgery on the synthesis of pain mediators, inflammatory mediator and oxygen free radicals. Methods: A total of 120 patients with fracture who underwent operation in the hospital between July 2014 and December 2016 were collected and divided into control group and observation group according to the random number table method, 60 cases in each group. Control group received morphine hydrochloride combined with ropivacaine for analgesia, observation group received hydromorphone hydrochloride combined with ropivacaine for analgesia, and the postoperative analgesia lasted for 48 h. The differences in serum levels of pain mediators, inflammatory mediators and oxidative stress indexes were compared between the two groups. Results: Immediately after operation, the differences in serum levels of pain mediators, inflammatory mediators and oxidative stress indexes were not statistically significant between the two groups. 48 h after operation, serum PGE2, SP, β-EP, IL-6, MCP-1, HMGB-1 and MDA levels of both groups of patients were significantly lower than those immediately after operation while Cu-Zn SOD and GSH-Px levels were significantly higher than those immediately after operation, and serum PGE2, SP, β-EP, IL-6, MCP-1, HMGB-1 and MDA levels of observation group were significantly lower than those of control group while Cu-Zn SOD and GSH-Px levels were significantly higher than those of control group. Conclusion: Hydromorphone hydrochloride combined with ropivacaine for PCEA after orthopedic surgery is effective in alleviating pain and inhibiting systemic inflammatory response.

  14. Protective Effect of Low Dose Gamma Irradiation against Oxidative Damage in Rats Administrated with Ferric- Nitrilotriacetate

    International Nuclear Information System (INIS)

    Mansonr, S.Z.

    2009-01-01

    Many studies have demonstrated the beneficial adaptive response of low dose gamma-irradiation. Low dose gamma-irradiation (LDR) might be effective for the prevention of various reactive oxygen species-related diseases. Ferric nitrilotriacetate (Fe-NTA) is a strong oxidant, which generates highly reactive hydroxyl radical and causes injuries of various organs including the kidney and liver. This study was designed to investigate the ability of low dose gamma-irradiation to restrain Fe-NT A induced oxidative stress. Sprague Dawley male albino rats were subjected to low dose gamma-irradiation (50 cGy). Animals were challenged with Fe-NT A (9 mg Fe/kg body weight, intraperitoneally). Results showed that Fe-NTA enhances lipid peroxidation (LPx) accompanied with reduction in glutathione (GSH) content, antioxidant enzymes, viz., glutathione peroxidase (GPX), glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT) and phase-U metabolizing enzyme glutathione-S-transferase (GST). Fe-NTA also enhances the concentration of blood urea nitrogen (BUN) and serum creatinine as well as alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyl transpeptidase (GGT) activities. Exposure to low dose gamma- irradiation (3 h after Fe-NTA administration) resulted in a significant decrease in LPx, BUN, serum creatinine contents as well as ALT, AST and GGT enzyme activities. GSH content; GST and antioxidant enzymes were also recovered to significant level. Thus, our data suggest that exposure to LDR might be a useful antioxidant mediator to suppress the Fe-NTA induced-oxidative damage in rats

  15. Protective Effect of Low Dose Gamma Irradiation against Oxidative Damage in Rats Administrated with Ferric- Nitrilotriacetate

    International Nuclear Information System (INIS)

    Mansonr, S.Z.

    2008-01-01

    Many studies have demonstrated the beneficial adaptive response of low dose gamma-irradiation. Low dose gamma-irradiation (LDR) might be effective for the prevention of various reactive oxygen species-related diseases. Ferric nitrilotriacetate (Fe-NTA) is a strong oxidant, which generates highly reactive hydroxyl radical and causes injuries of various organs including the kidney and liver. This study was designed to investigate the ability of low dose gamma-irradiation to restrain Fe-NT A induced oxidative stress. Sprague Dawley male albino rats were subjected to low dose gamma-irradiation (50 cGy). Animals were challenged with Fe-NT A (9 mg Fe/kg body weight, intraperitoneally). Results showed that Fe-NTA enhances lipid peroxidation (LPx) accompanied with reduction in glutathione (GSH) content, antioxidant enzymes, viz., glutathione peroxidase (GPX), glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT) and phase-U metabolizing enzyme glutathione-S-transferase (GST). Fe-NTA also enhances the concentration of blood urea nitrogen (BUN) and serum creatinine as well as alanine aminotransferase (ALT), aspartate aminotransferase (AST) and gamma-glutamyl transpeptidase (GGT) activities. Exposure to low dose gamma- irradiation (3 h after Fe-NTA administration) resulted in a significant decrease in LPx, BUN, serum creatinine contents as well as ALT, AST and GGT enzyme activities. GSH content; GST and antioxidant enzymes were also recovered to significant level. Thus, our data suggest that exposure to LDR might be a useful antioxidant mediator to suppress the Fe-NTA induced-oxidative damage in rats

  16. Female plumage colour influences seasonal oxidative damage and testosterone profiles in a songbird.

    Science.gov (United States)

    Vitousek, Maren N; Stewart, Rosemary A; Safran, Rebecca J

    2013-10-23

    Across diverse taxa, morphological traits mediate social interactions and mate selection. Physiological constraints on signal elaboration have been widely documented, but the potential for trait display to influence physiological state remains poorly understood. We tested for the presence of causal links between ventral plumage colour-a trait known to covary with reproductive performance-and physiological measures in female North American barn swallows, Hirundo rustica erythrogaster. Naturally darker swallows have lower levels of plasma oxidative damage. Females manipulated to display darker ventral plumage during reproduction rapidly decreased oxidative damage, adopting the physiological state of naturally darker individuals. These results support the presence of a social mechanism that links static plumage traits with the physiological state of their bearer during trait advertisement, long after the completion of signal development.

  17. Antioxidant capacity contributes to protection of ketone bodies against oxidative damage induced during hypoglycemic conditions.

    Science.gov (United States)

    Haces, María L; Hernández-Fonseca, Karla; Medina-Campos, Omar N; Montiel, Teresa; Pedraza-Chaverri, José; Massieu, Lourdes

    2008-05-01

    Ketone bodies play a key role in mammalian energy metabolism during the suckling period. Normally ketone bodies' blood concentration during adulthood is very low, although it can rise during starvation, an exogenous infusion or a ketogenic diet. Whenever ketone bodies' levels increase, their oxidation in the brain rises. For this reason they have been used as protective molecules against refractory epilepsy and in experimental models of ischemia and excitotoxicity. The mechanisms underlying the protective effect of these compounds are not completely understood. Here, we studied a possible antioxidant capacity of ketone bodies and whether it contributes to the protection against oxidative damage induced during hypoglycemia. We report for the first time the scavenging capacity of the ketone bodies, acetoacetate (AcAc) and both the physiological and non-physiological isomers of beta-hydroxybutyrate (D- and L-BHB, respectively), for diverse reactive oxygen species (ROS). Hydroxyl radicals (.OH) were effectively scavenged by D- and L-BHB. In addition, the three ketone bodies were able to reduce cell death and ROS production induced by the glycolysis inhibitor, iodoacetate (IOA), while only D-BHB and AcAc prevented neuronal ATP decline. Finally, in an in vivo model of insulin-induced hypoglycemia, the administration of D- or L-BHB, but not of AcAc, was able to prevent the hypoglycemia-induced increase in lipid peroxidation in the rat hippocampus. Our data suggest that the antioxidant capacity contributes to protection of ketone bodies against oxidative damage in in vitro and in vivo models associated with free radical production and energy impairment.

  18. Activation of Nrf2-mediated oxidative stress response in macrophages by hypochlorous acid

    International Nuclear Information System (INIS)

    Pi Jingbo; Zhang Qiang; Woods, Courtney G.; Wong, Victoria; Collins, Sheila; Andersen, Melvin E.

    2008-01-01

    Hypochlorous acid (HOCl), a potent oxidant generated when chlorine gas reacts with water, is important in the pathogenesis of many disorders. Transcription factor Nrf2-mediated antioxidant response represents a critical cellular defense mechanism that serves to maintain intracellular redox homeostasis and limit oxidative damage. In the present study, the effect of HOCl on Nrf2 activation was investigated in macrophages, one of the target cells of chlorine gas exposure. Exposure of RAW 264.7 macrophages to HOCl resulted in increased protein levels of Nrf2 in nuclear extractions, as well as a time- and dose-dependent increase in the expression of Nrf2 target genes, including heme oxygenase-1, NAD(P)H:quinone oxidoreductase 1 (NQO-1), glutamate cysteine ligase catalytic subunit (GCLC), and glutathione synthetase (GS). Additionally, intracellular glutathione (GSH), which is the prime scavenger for HOCl in cells, decreased within the first hour of HOCl exposure. The decline was followed by a GSH rebound that surpassed the initial basal levels by up to 4-fold. This reversal in GSH levels closely correlated with the gene expression profile of GCLC and GS. To study the mechanisms of Nrf2 activation in response to HOCl exposure, we examined the effects of several antioxidants on Nrf2-mediated response. Pretreatment with cell-permeable catalase, N-acetyl-L-cysteine or GSH-monoethyl ester markedly reduced expression of NQO-1 and GCLC under HOCl challenge conditions, suggesting intracellular ROS-scavenging capacity affects HOCl-induced Nrf2 activation. Importantly, pre-activation of Nrf2 with low concentrations of pro-oxidants protected the cells against HOCl-induced cell damage. Taken together, we provide direct evidence that HOCl activates Nrf2-mediated antioxidant response, which protects cells from oxidative damage

  19. Free radical scavenging and the expression of potentially lethal damage in X-irradiated repair-deficient Escherichia coli

    International Nuclear Information System (INIS)

    Billen, D.

    1987-01-01

    When cells are exposed to ionizing radiation, they suffer lethal damage (LD), potentially lethal damage (PLD), and sublethal damage (SLD). All three forms of damage may be caused by direct or indirect radiation action or by the interaction of indirect radiation products with direct DNA damage. In this report I examine the expression of LD and PLD caused by the indirect action of X rays in isogenic, repair-deficient Escherichia coli. The radiosensitivity of a recA mutant, deficient both in pre- and post replication recombination repair and SOS induction (inducible error-prone repair), was compared to that of a recB mutant which is recombination deficient but SOS proficient and to a previously studied DNA polymerase 1-deficient mutant (polA) which lacks the excision repair pathway. Indirect damage by water radicals (primarily OH radicals) was circumvented by the presence of 2 M glycerol during irradiation. Indirect X-ray damage by water radicals accounts for at least 85% of the PLD found in exposed repair-deficient cells. The DNA polymerase 1-deficient mutant is most sensitive to indirect damage with the order of sensitivity polA1 greater than recB greater than or equal to recA greater than wild type. For the direct effects of X rays the order of sensitivity is recA greater than recB greater than polA1 greater than wild type. The significance of the various repair pathways in mitigating PLD by direct and indirect damage is discussed

  20. Exploring the Role of Persulfate in the Activation Process: Radical Precursor Versus Electron Acceptor.

    Science.gov (United States)

    Yun, Eun-Tae; Yoo, Ha-Young; Bae, Hyokwan; Kim, Hyoung-Il; Lee, Jaesang

    2017-09-05

    This study elucidates the mechanism behind persulfate activation by exploring the role of various oxyanions (e.g., peroxymonosulfate, periodate, and peracetate) in two activation systems utilizing iron nanoparticle (nFe 0 ) as the reducing agent and single-wall carbon nanotubes (CNTs) as electron transfer mediators. Since the tested oxyanions serve as both electron acceptors and radical precursors in most cases, oxidative degradation of organics was achievable through one-electron reduction of oxyanions on nFe 0 (leading to radical-induced oxidation) and electron transfer mediation from organics to oxyanions on CNTs (leading to oxidative decomposition involving no radical formation). A distinction between degradative reaction mechanisms of the nFe 0 /oxyanion and CNT/oxyanion systems was made in terms of the oxyanion consumption efficacy, radical scavenging effect, and EPR spectral analysis. Statistical study of substrate-specificity and product distribution implied that the reaction route induced on nFe 0 varies depending on the oxyanion (i.e., oxyanion-derived radical), whereas the similar reaction pathway initiates organic oxidation in the CNT/oxyanion system irrespective of the oxyanion type. Chronoamperometric measurements further confirmed electron transfer from organics to oxyanions in the presence of CNTs, which was not observed when applying nFe 0 instead.

  1. The oxidative hypothesis of senescence

    Directory of Open Access Journals (Sweden)

    Gilca M

    2007-01-01

    Full Text Available The oxidative hypothesis of senescence, since its origin in 1956, has garnered significant evidence and growing support among scientists for the notion that free radicals play an important role in ageing, either as "damaging" molecules or as signaling molecules. Age-increasing oxidative injuries induced by free radicals, higher susceptibility to oxidative stress in short-lived organisms, genetic manipulations that alter both oxidative resistance and longevity and the anti-ageing effect of caloric restriction and intermittent fasting are a few examples of accepted scientific facts that support the oxidative theory of senescence. Though not completely understood due to the complex "network" of redox regulatory systems, the implication of oxidative stress in the ageing process is now well documented. Moreover, it is compatible with other current ageing theories (e.g., those implicating the mitochondrial damage/mitochondrial-lysosomal axis, stress-induced premature senescence, biological "garbage" accumulation, etc. This review is intended to summarize and critically discuss the redox mechanisms involved during the ageing process: sources of oxidant agents in ageing (mitochondrial -electron transport chain, nitric oxide synthase reaction- and non-mitochondrial- Fenton reaction, microsomal cytochrome P450 enzymes, peroxisomal β -oxidation and respiratory burst of phagocytic cells, antioxidant changes in ageing (enzymatic- superoxide dismutase, glutathione-reductase, glutathion peroxidase, catalase- and non-enzymatic glutathione, ascorbate, urate, bilirubine, melatonin, tocopherols, carotenoids, ubiquinol, alteration of oxidative damage repairing mechanisms and the role of free radicals as signaling molecules in ageing.

  2. Effect of Mucuna pruriens on oxidative stress mediated damage in aged rat sperm.

    Science.gov (United States)

    Suresh, Sekar; Prithiviraj, Elumalai; Prakash, Seppan

    2010-02-01

    Mucuna pruriens Linn., a leguminous plant, has been recognized as an aphrodisiac and spermatogenic agent. Protective efficacy of M. pruriens on reactive oxygen species (ROS)-induced pathophysiological alterations in structural and functional integrity of epididymal sperm in aged Wister albino rat was analysed. Animals were grouped as groups I, II, III and IV, i.e. young (control), aged, aged treated with ethanolic extract (200 mg/kg b.w.) of M. pruriens and young rats treated with M. pruriens, respectively. At the end of the experimental period, i.e. after 60 days animals were sacrificed, epididymal sperm were collected and subjected to count, viability, motility, morphology and morphometric analysis. Enzymatic and non-enzymatic antioxidants, ROS, lipid peroxidation (LPO), DNA damage, chromosomal integrity and mitochondrial membrane potential were estimated. Results obtained from the aged animals showed significant reduction in sperm count, viability and motility, increased morphological damage and an increase in the number of sperm with cytoplasmic remnant, and these alterations were significantly reversed in M. pruriens treated group. Significant increase in LPO, HO and H(2)O(2) production and significant decline in the levels of the enzymatic and non-enzymatic antioxidants were observed in the aged animals. Supplementation of M. pruriens significantly reduced ROS and LPO production and significant increase in both enzymatic and non-enzymatic antioxidant levels. There were significant DNA damage, loss of chromosomal integrity and increase in mitochondrial membrane permeability in aged rat sperm. This was significantly reduced in group III. Present observation indicates the antioxidant enhancing property, free radical quenching ability and spermatogenic efficacy of the M. pruriens. Collectively, sperm damage in ageing was significantly reduced by quenching ROS, improving antioxidant defence system and mitochondrial function.

  3. [The relationship between neuroendocrine dysfunction and free-radical oxidation in old age alcoholism].

    Science.gov (United States)

    Vinogradov, D B; Mingazov, A Kh; Izarovskaya, I V; Babin, K A; Sinitsky, A I

    2015-01-01

    to study the relationship between dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis and free-radical oxidation in old age alcoholism. Authors examined 46 men and women, aged 60-80 years, with alcoholism. Contents of cortisol, lipid peroxidation products and the level of an oxidatively modified protein were measured. A decrease in blood cortisol content and correlations between its level and activity of free-radical oxidation were identified. The severity of neuroendocrine dysfunction in old patients was sex-related. It has been suggested that the impairment of HPA system activity may be a cause of oxidative stress and development of alcoholism.

  4. Potential repair of free radical adducts of dGMP and dG by a series of reductants. A pulse radiolytic study

    International Nuclear Information System (INIS)

    O'Neill, P.; Chapman, P.W.

    1985-01-01

    Using the technique of pulse radiolysis, it has been demonstrated that the interaction of hydroxyl-radical adducts of dG and dGMP with a series of reductants with different oxidation potentials at pH 7.0-7.4 proceeds via an electron transfer process (k approx. 1.4-34 x 10 8 dm 3 mol -1 s -1 ). The one-electron oxidation of dGMP (dG) by Br2-anion radicals was shown to result in the formation of a species, the properties of which are similar to those of the OH-radical adduct of dGMP with oxidizing properties based upon both spectral and kinetic information. The nature of the dGMP species produced on interaction with Br2-anion radicals to produce specific base damage. The implications of these findings are presented in terms of potential free radical repair of hydroxyl radical damage and of synergistic effects whereby one reductant may be regenerated at the expense of another reductant. (author)

  5. Gallic acid prevents nonsteroidal anti-inflammatory drug-induced gastropathy in rat by blocking oxidative stress and apoptosis.

    Science.gov (United States)

    Pal, Chinmay; Bindu, Samik; Dey, Sumanta; Alam, Athar; Goyal, Manish; Iqbal, Mohd Shameel; Maity, Pallab; Adhikari, Susanta S; Bandyopadhyay, Uday

    2010-07-15

    Nonsteroidal anti-inflammatory drug (NSAID)-induced oxidative stress plays a critical role in gastric mucosal cell apoptosis and gastropathy. NSAIDs induce the generation of hydroxyl radical ((*)OH) through the release of free iron, which plays an important role in developing gastropathy. Thus, molecules having both iron-chelating and antiapoptotic properties will be beneficial in preventing NSAID-induced gastropathy. Gallic acid (GA), a polyphenolic natural product, has the capacity to chelate free iron. Here, we report that GA significantly prevents, as well as heals, NSAID-induced gastropathy. In vivo, GA blocks NSAID-mediated mitochondrial oxidative stress by preventing mitochondrial protein carbonyl formation, lipid peroxidation, and thiol depletion. In vitro, GA scavenges free radicals and blocks (*)OH-mediated oxidative damage. GA also attenuates gastric mucosal cell apoptosis in vivo as well as in vitro in cultured gastric mucosal cells as evident from the TUNEL assay. GA prevents NSAID-induced activation of caspase-9, a marker for the mitochondrial pathway of apoptosis, and restores NSAID-mediated collapse of the mitochondrial transmembrane potential and dehydrogenase activity. Thus, the inhibition of mitochondrial oxidative stress by GA is associated with the inhibition of NSAID-induced mitochondrial dysfunction and activation of apoptosis in gastric mucosal cells, which are responsible for gastric injury or gastropathy. Copyright 2010 Elsevier Inc. All rights reserved.

  6. Oxidative Stress and Proinflammatory Cytokines Contribute to Demyelination and Axonal Damage in a Cerebellar Culture Model of Neuroinflammation

    Science.gov (United States)

    di Penta, Alessandra; Moreno, Beatriz; Reix, Stephanie; Fernandez-Diez, Begoña; Villanueva, Maite; Errea, Oihana; Escala, Nagore; Vandenbroeck, Koen; Comella, Joan X.; Villoslada, Pablo

    2013-01-01

    Background Demyelination and axonal damage are critical processes in the pathogenesis of multiple sclerosis (MS). Oxidative stress and pro-inflammatory cytokines elicited by inflammation mediates tissue damage. Methods/Principal Findings To monitor the demyelination and axonal injury associated with microglia activation we employed a model using cerebellar organotypic cultures stimulated with lipopolysaccharide (LPS). Microglia activated by LPS released pro-inflammatory cytokines (IL-1β, IL-6 and TNFα), and increased the expression of inducible nitric oxide synthase (iNOS) and production of reactive oxygen species (ROS). This activation was associated with demyelination and axonal damage in cerebellar cultures. Axonal damage, as revealed by the presence of non-phosphorylated neurofilaments, mitochondrial accumulation in axonal spheroids, and axonal transection, was associated with stronger iNOS expression and concomitant increases in ROS. Moreover, we analyzed the contribution of pro-inflammatory cytokines and oxidative stress in demyelination and axonal degeneration using the iNOS inhibitor ethyl pyruvate, a free-scavenger and xanthine oxidase inhibitor allopurinol, as well as via blockage of pro-inflammatory cytokines using a Fc-TNFR1 construct. We found that blocking microglia activation with ethyl pyruvate or allopurinol significantly decreased axonal damage, and to a lesser extent, demyelination. Blocking TNFα significantly decreased demyelination but did not prevented axonal damage. Moreover, the most common therapy for MS, interferon-beta, was used as an example of an immunomodulator compound that can be tested in this model. In vitro, interferon-beta treatment decreased oxidative stress (iNOS and ROS levels) and the release of pro-inflammatory cytokines after LPS stimulation, reducing axonal damage. Conclusion The model of neuroinflammation using cerebellar culture stimulated with endotoxin mimicked myelin and axonal damage mediated by the combination of

  7. Mediator oxidation systems in organic electrosynthesis

    International Nuclear Information System (INIS)

    Ogibin, Yurii N; Elinson, Michail N; Nikishin, Gennady I

    2009-01-01

    The data on the use of mediator oxidation systems activated by electric current (anodic or parallel anodic and cathodic) in organic electrosynthesis are considered and generalised. Electrochemical activation of these systems permits successful application of catalytic versions and easy scaling of mediator-promoted processes. Chemical and environmental advantages of electrochemical processes catalysed by mediator oxidation systems are demonstrated. Examples of the application of organic and inorganic mediators for the oxidation of various classes of organic compounds under conditions of electrolysis are given.

  8. Unusual spin-trap chemistry for the reaction of hydroxyl radical with the carcinogen N-nitrosodimethylamine

    Energy Technology Data Exchange (ETDEWEB)

    Wink, D A [National Cancer Inst., Frederick, MD (United States); Desrosiers, M F [National Inst. of Standards and Technology, Gaithersburg, MD (United States)

    1991-01-01

    The reaction of the potent carcinogen N-nitrosodimethylamine (NDMA) with hydroxyl radical generated via radiolysis was studied using EPR techniques. Attempts to spin trap NDMA radical intermediates with 3.5-dibromo-4-nitrosobenzene sulfonate (DBNBS) produced only unusual DBNBS radicals. One of these radicals was shown to be generated by both reaction of DBNBS with nitric oxide, and direct oxidation of DBNBS with an inorganic oxidant (BR{sub 2}{sup -}). Another DBNBS radical was identified as a sulfite spin adduct resulting from the degradation of DBNBS by a NDMA reactive inter-mediate. In the absence of DBNBS, hydroxyl radical reaction with NDMA gave the dimethylnitroxide produced an EPR spectrum nearly identical to that of NDMA solutions with DBNBS added before radiolysis. A proposed mechanism accounting for these observations is presented. (author).

  9. Unusual spin-trap chemistry for the reaction of hydroxyl radical with the carcinogen N-nitrosodimethylamine

    International Nuclear Information System (INIS)

    Wink, D.A.; Desrosiers, M.F.

    1991-01-01

    The reaction of the potent carcinogen N-nitrosodimethylamine (NDMA) with hydroxyl radical generated via radiolysis was studied using EPR techniques. Attempts to spin trap NDMA radical intermediates with 3.5-dibromo-4-nitrosobenzene sulfonate (DBNBS) produced only unusual DBNBS radicals. One of these radicals was shown to be generated by both reaction of DBNBS with nitric oxide, and direct oxidation of DBNBS with an inorganic oxidant (BR 2 - ). Another DBNBS radical was identified as a sulfite spin adduct resulting from the degradation of DBNBS by a NDMA reactive inter-mediate. In the absence of DBNBS, hydroxyl radical reaction with NDMA gave the dimethylnitroxide produced an EPR spectrum nearly identical to that of NDMA solutions with DBNBS added before radiolysis. A proposed mechanism accounting for these observations is presented. (author)

  10. Investigation of the role of bicyclic peroxy radicals in the oxidation mechanism of toluene.

    Science.gov (United States)

    Birdsall, Adam W; Andreoni, John F; Elrod, Matthew J

    2010-10-07

    The products of the primary OH-initiated oxidation of toluene were investigated using the turbulent flow chemical ionization mass spectrometry technique under different oxygen, NO, and initial OH radical concentrations as well as a range of total pressures. The bicyclic peroxy radical intermediate, a key proposed intermediate species in the Master Chemical Mechanism (MCM) for the atmospheric oxidation of toluene, was detected for the first time. The toluene oxidation mechanism was shown to have a strong oxygen concentration dependence, presumably due to the central role of the bicyclic peroxy radical in determining the stable product distribution at atmospheric oxygen concentrations. The results also suggest a potential role for bicyclic peroxy radical + HO(2) reactions at high HO(2)/NO ratios. These reactions are postulated to be a source of the inconsistencies between environmental chamber results and predictions from the MCM.

  11. Flavonoids from Agrimonia pilosa Ledeb: Free Radical Scavenging and DNA Oxidative Damage Protection Activities and Analysis of Bioactivity-Structure Relationship Based on Molecular and Electronic Structures.

    Science.gov (United States)

    Zhu, Liancai; Chen, Jinqiu; Tan, Jun; Liu, Xi; Wang, Bochu

    2017-02-26

    To clarify the substantial basis of the excellent antioxidant capacity of Agrimonia pilosa Ledeb. Fourteen flavonoids were isolated and identified from Agrimonia pilosa Ledeb, seven of which have notable DPPH radical scavenging activities, i.e., catechin, luteolin, quercetin, quercitrin, hyperoside, rutin, luteolin-7- O -β-glucoside with IC 50 values of 5.06, 7.29, 4.36, 7.12, 6.34, 6.36 and 8.12 µM, respectively. The DNA nicking assay showed that five flavonoids from Agrimonia pilosa Ledeb-taxifolin, catechin, hyperoside, quercitrin and rutin-have good protective activity against DNA oxidative damage. Further, we analyzed the bioactivity-structure relationship of these 14 flavonoids by applying quantum theory. According to their O-H bond dissociation enthalpy (BDE), C ring's spin density and stable molecular structure, the relationship between their structures and radical scavenging capacities was evaluated and clarified. We found that among flavonoid aglycones from Agrimonia pilosa Ledeb, the O-H BDE of quercetin is lowest with the values of 69.02 and the O-H BDE of apigenin is highest with the values of 79.77. It is interesting that the O-H BDE value of isovitexin (78.55) with glycoside at C-6 position is lower than that of its aglycone (79.77) and vitexin (99.20) with glycoside at C-8 position. Further analysis indicated that the glycosidation of flavonoids at C-6 in the A-ring makes a more uniform distribution of spin density and improves the stability of free radicals leading to the increase in antioxidant capacity. Flavonoids with good antioxidant capacity might contribute to the pharmacological effects of Agrimonia pilosa Ledeb.

  12. Flavonoids from Agrimonia pilosa Ledeb: Free Radical Scavenging and DNA Oxidative Damage Protection Activities and Analysis of Bioactivity-Structure Relationship Based on Molecular and Electronic Structures

    Directory of Open Access Journals (Sweden)

    Liancai Zhu

    2017-02-01

    Full Text Available To clarify the substantial basis of the excellent antioxidant capacity of Agrimonia pilosa Ledeb. Fourteen flavonoids were isolated and identified from Agrimonia pilosa Ledeb, seven of which have notable DPPH radical scavenging activities, i.e., catechin, luteolin, quercetin, quercitrin, hyperoside, rutin, luteolin-7-O-β-glucoside with IC50 values of 5.06, 7.29, 4.36, 7.12, 6.34, 6.36 and 8.12 µM, respectively. The DNA nicking assay showed that five flavonoids from Agrimonia pilosa Ledeb—taxifolin, catechin, hyperoside, quercitrin and rutin—have good protective activity against DNA oxidative damage. Further, we analyzed the bioactivity-structure relationship of these 14 flavonoids by applying quantum theory. According to their O-H bond dissociation enthalpy (BDE, C ring’s spin density and stable molecular structure, the relationship between their structures and radical scavenging capacities was evaluated and clarified. We found that among flavonoid aglycones from Agrimonia pilosa Ledeb, the O-H BDE of quercetin is lowest with the values of 69.02 and the O-H BDE of apigenin is highest with the values of 79.77. It is interesting that the O-H BDE value of isovitexin (78.55 with glycoside at C-6 position is lower than that of its aglycone (79.77 and vitexin (99.20 with glycoside at C-8 position. Further analysis indicated that the glycosidation of flavonoids at C-6 in the A-ring makes a more uniform distribution of spin density and improves the stability of free radicals leading to the increase in antioxidant capacity. Flavonoids with good antioxidant capacity might contribute to the pharmacological effects of Agrimonia pilosa Ledeb.

  13. Hydroxytyrosol Protects against Oxidative DNA Damage in Human Breast Cells

    Directory of Open Access Journals (Sweden)

    José J. Gaforio

    2011-10-01

    Full Text Available Over recent years, several studies have related olive oil ingestion to a low incidence of several diseases, including breast cancer. Hydroxytyrosol and tyrosol are two of the major phenols present in virgin olive oils. Despite the fact that they have been linked to cancer prevention, there is no evidence that clarifies their effect in human breast tumor and non-tumor cells. In the present work, we present hydroxytyrosol and tyrosol’s effects in human breast cell lines. Our results show that hydroxytyrosol acts as a more efficient free radical scavenger than tyrosol, but both fail to affect cell proliferation rates, cell cycle profile or cell apoptosis in human mammary epithelial cells (MCF10A or breast cancer cells (MDA-MB-231 and MCF7. We found that hydroxytyrosol decreases the intracellular reactive oxygen species (ROS level in MCF10A cells but not in MCF7 or MDA-MB-231 cells while very high amounts of tyrosol is needed to decrease the ROS level in MCF10A cells. Interestingly, hydroxytyrosol prevents oxidative DNA damage in the three breast cell lines. Therefore, our data suggest that simple phenol hydroxytyrosol could contribute to a lower incidence of breast cancer in populations that consume virgin olive oil due to its antioxidant activity and its protection against oxidative DNA damage in mammary cells.

  14. Oxidative Damage and Its Possible Mechanism

    Directory of Open Access Journals (Sweden)

    Tingting Wang

    2016-06-01

    Full Text Available Purpose: The paper tries to assess the protective effect of fisetin against •OH-induced DNAdamage, then to investigate the possible mechanism.Methods: The protective effect was evaluated based on the content of malondialdehyde(MDA. The possible mechanism was analyzed using various antioxidant methods in vitro,including •OH scavenging (deoxyribose degradation, •O2- scavenging (pyrogallolautoxidation, DPPH• scavenging, ABTS•+ scavenging, and Cu2+-reducing power assays.Results: Fisetin increased dose-dependently its protective percentages against •OH-inducedDNA damage (IC50 value =1535.00±29.60 μM. It also increased its radical-scavengingpercentages in a dose-dependent manner in various antioxidants assays. Its IC50 values in•OH scavenging, •O2- scavenging, DPPH• scavenging, ABTS•+ scavenging, and Cu2+-reducing power assays, were 47.41±4.50 μM, 34.05±0.87 μM, 9.69±0.53 μM, 2.43±0.14μM, and 1.49±0.16 μM, respectively.Conclusion: Fisetin can effectively protect DNA against •OH-induced oxidative damagepossibly via reactive oxygen species (ROS scavenging approach, which is assumed to behydrogen atom (H• and/or single electron (e donation (HAT/SET pathways. In the HATpathway, the 3’,4’-dihydroxyl moiety in B ring of fisetin is thought to play an importantrole, because it can be ultimately oxidized to a stable ortho-benzoquinone form.

  15. Methyl Radicals in Oxidative Coupling of Methane Directly Confirmed by Synchrotron VUV Photoionization Mass Spectroscopy

    Science.gov (United States)

    Luo, Liangfeng; Tang, Xiaofeng; Wang, Wendong; Wang, Yu; Sun, Shaobo; Qi, Fei; Huang, Weixin

    2013-01-01

    Gas-phase methyl radicals have been long proposed as the key intermediate in catalytic oxidative coupling of methane, but the direct experimental evidence still lacks. Here, employing synchrotron VUV photoionization mass spectroscopy, we have directly observed the formation of gas-phase methyl radicals during oxidative coupling of methane catalyzed by Li/MgO catalysts. The concentration of gas-phase methyl radicals correlates well with the yield of ethylene and ethane products. These results lead to an enhanced fundamental understanding of oxidative coupling of methane that will facilitate the exploration of new catalysts with improved performance. PMID:23567985

  16. Regulated production of free radicals by the mitochondrial electron transport chain: Cardiac ischemic preconditioning.

    Science.gov (United States)

    Matsuzaki, Satoshi; Szweda, Pamela A; Szweda, Luke I; Humphries, Kenneth M

    2009-11-30

    Excessive production of free radicals by mitochondria is associated with, and likely contributes to, the progression of numerous pathological conditions. Nevertheless, the production of free radicals by the mitochondria may have important biological functions under normal or stressed conditions by activating or modulating redox-sensitive cellular signaling pathways. This raises the intriguing possibility that regulated mitochondrial free radical production occurs via mechanisms that are distinct from pathologies associated with oxidative damage. Indeed, the capacity of mitochondria to produce free radicals in a limited manner may play a role in ischemic preconditioning, the phenomenon whereby short bouts of ischemia protect from subsequent prolonged ischemia and reperfusion. Ischemic preconditioning can thus serve as an important model system for defining regulatory mechanisms that allow for transient, signal-inducing, production of free radicals by mitochondria. Defining how these mechanism(s) occur will provide insight into therapeutic approaches that minimize oxidative damage without altering normal cellular redox biology. The aim of this review is to present and discuss evidence for the regulated production of superoxide by the electron transport chain within the ischemic preconditioning paradigm of redox regulation.

  17. A possible mechanism for transpupillary thermotherapy: nitric-oxide-related cellular damage.

    Science.gov (United States)

    Ozdek, Sengul; Urgancioglu, Berrak; Turkcu, Ummuhani Ozel; Bilgihan, Ayse

    2007-08-01

    To determine the oxidative stress markers on rabbit vitreous following transpupillary thermotherapy (TTT) application. The pigmented rabbit eyes were divided into 3 groups, each containing 6 eyes. Group 1 was used as a control group. Twelve eyes underwent TTT with a power of 250 mW (group 2) and 800 mW (group 3), with a diameter of 3000 microm and duration of 60 s; 24 h after laser application, vitreous samples were collected. Nitric oxide (NO) and malondialdehyde (MDA) levels and superoxide dismutase (SOD) activities were determined in all groups. NO levels were statistically significantly higher in all groups when compared with the control group (p 0.05). Our results support the hypothesis that TTT application induces NO synthesis, which may lead to occlusion at choroidal neovessels. Because of the nonsignificantly increased levels of MDA and decrease of SOD activities there maybe only a weak relation between lipid peroxidation induced by free oxygen radicals and TTT-induced vascular damage.

  18. Laccase catalyzed grafting of-N-OH type mediators to lignin via radical-radical coupling

    NARCIS (Netherlands)

    Munk, L.; Punt, A.M.; Kabel, M.A.; Meyer, A.S.

    2017-01-01

    Lignin is an underexploited resource in biomass refining. Laccases (EC 1.10.3.2) catalyze oxidation of phenolic hydroxyls using O2 as electron acceptor and may facilitate lignin modification in the presence of mediators. This study assessed the reactivity of four different synthetic mediators by

  19. Nitric oxide as a mediator of gastrointestinal mucosal injury?—Say it ain't so

    Directory of Open Access Journals (Sweden)

    Paul Kubes

    1995-01-01

    Full Text Available Nitric oxide has been suggested as a contributor to tissue injury in various experimental models of gastrointestinal inflammation. However, there is overwhelming evidence that nitric oxide is one of the most important mediators of mucosal defence, influencing such factors as mucus secretion, mucosal blood flow, ulcer repair and the activity of a variety of mucosal immunocytes. Nitric oxide has the capacity to down-regulate inflammatory responses in the gastrointestinal tract, to scavenge various free radical species and to protect the mucosa from injury induced by topical irritants. Moreover, questions can be raised regarding the evidence purported to support a role for nitric oxide in producing tissue injury. In this review, we provide an overview of the evidence supporting a role for nitric oxide in protecting the gastrointestinal tract from injury.

  20. THE PROTECTIVE ROLE OF VITAMIN E AGAINST OXYGEN FREE RADICAL AND DNA DAMAGE IN CHILDREN WITH β-THALASSEMIA MAJOR

    International Nuclear Information System (INIS)

    NASSAR, E.M.

    2008-01-01

    The present study aimed to determine the benefits of vitamin E as antioxidant supplement in β thalassemia children who are at risk of iron overload due to multiple blood transfusion and oxidative stress. Antioxidant markers, oxidative products, hematological parameters and biomarkers of cell damage were studied in 24 transfusion-dependent β -thalassemia children before and after treatment with vitamin E at a dose of 10 mg/kg /day for a period of four weeks. Plasma thiobarbituric acid reactive species (TBARS) and urinary 8-hydroxy-2 ' -deoxyguanosine (8-OHdG) were analyzed as oxidative markers, whereas the plasma vitamin E and the activities of the antioxidant enzymes glutathione peroxidase (GSH-Px), superoxide dismutase(SOD) and catalase were measured to show the antioxidant status of thalassemic children. All these parameters were also studied in 15 non-anemic healthy controls .The results showed that all the patients had increased signs of iron overload and cell damage that were obvious from the increase in serum iron, ferritin, alanine transaminases (ALT), aspartate transaminases (AST) and both total and direct bilirubin .The level of plasma vitamin E in the thalassemia patients were found to be significantly lower as compared to normal subjects (1.3 ± 0.7 and 3.14 ± 1.5 mg % , respectively). The activities of antioxidants enzymes, glutathione peroxidase and catalase in untreated β-thalassemic patients were found to be significantly (P<0.001) less than that of the normal subjects. However, SOD level was significantly increased. Markers of free radical injury such as TBARS , urinary 8-OHdG levels in thalassemic children were significantly higher than control levels . All these changes in the antioxidant status as well as the hematological parameters, iron overload and cell damage markers in β-thalassemia patients showed significant improvement after vitamin E supplementation. Vitamin E levels showed significant positive correlations with each of Hb, GSH

  1. High-throughput optimization of nitroxide mediated radical polymerizations as basis for the synthesis of temperature-responsive copolymers

    NARCIS (Netherlands)

    Hoogenboom, R.; Becer, C.R.; Eggenhuisen, T.M.; Schubert, U.S.

    2008-01-01

    The development of controlled radical polymn. techniques, namely atom transfer radical polymn. (ATRP), reversible addn. fragmentation transfer (RAFT) and nitroxide mediated radical polymn. (NMP), have opened up unprecedented possibilities for the synthesis of well-defined macromol. architectures

  2. Possible GABAergic modulation in the protective effect of zolpidem in acute hypoxic stress-induced behavior alterations and oxidative damage.

    Science.gov (United States)

    Kumar, Anil; Goyal, Richa

    2008-03-01

    Hypoxia is an environmental stressor that is known to elicit alterations in both the autonomic nervous system and endocrine functions. The free radical or oxidative stress theory holds that oxidative reactions are mainly underlying neurodegenerative disorders. In fact among complex metabolic reactions occurring during hypoxia, many could be related to the formation of oxygen derived free radicals, causing a wide spectrum of cell damage. In present study, we investigated possible involvement of GABAergic mechanism in the protective effect of zolpidem against acute hypoxia-induced behavioral modification and biochemical alterations in mice. Mice were subjected to acute hypoxic stress for a period of 2 h. Acute hypoxic stress for 2 h caused significant impairment in locomotor activity, anxiety-like behavior, and antinocioceptive effect in mice. Biochemical analysis revealed a significant increased malondialdehyde, nitrite concentrations and depleted reduced glutathione and catalase levels. Pretreatment with zolpidem (5 and 10 mg/kg, i.p.) significantly improved locomotor activity, anti-anxiety effect, reduced tail flick latency and attenuated oxidative damage (reduced malondialdehyde, nitrite concentration, and restoration of reduced glutathione and catalase levels) as compared to stressed control (hypoxia) (P zolpidem (5 mg/kg) was blocked significantly by picrotoxin (1.0 mg/kg) or flumazenil (2 mg/kg) and potentiated by muscimol (0.05 mg/kg) in hypoxic animals (P zolpidem (5 mg/kg) per se (P zolpidem against hypoxic stress.

  3. Quercitrin protects skin from UVB-induced oxidative damage

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Yuanqin [Cancer Institute, The First Affiliated Hospital, China Medical University, Shenyang (China); Graduate Center for Toxicology, University of Kentucky, 1095 VA Drive, Lexington, KY (United States); Li, Wenqi; Son, Young-Ok; Sun, Lijuan; Lu, Jian; Kim, Donghern; Wang, Xin [Graduate Center for Toxicology, University of Kentucky, 1095 VA Drive, Lexington, KY (United States); Yao, Hua [Department of Stomatology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang (China); Wang, Lei; Pratheeshkumar, Poyil; Hitron, Andrew J. [Graduate Center for Toxicology, University of Kentucky, 1095 VA Drive, Lexington, KY (United States); Luo, Jia [Department of Internal Medicine, University of Kentucky, 800 Rose Street, Lexington, KY (United States); Gao, Ning [Department of Pharmacognos, College of Pharmacy, 3rd Military Medical University, Chongqing (China); Shi, Xianglin [Graduate Center for Toxicology, University of Kentucky, 1095 VA Drive, Lexington, KY (United States); Zhang, Zhuo, E-mail: zhuo.zhang@uky.edu [Graduate Center for Toxicology, University of Kentucky, 1095 VA Drive, Lexington, KY (United States)

    2013-06-01

    Exposure of the skin to ultraviolet B (UVB) radiation causes oxidative damage to skin, resulting in sunburn, photoaging, and skin cancer. It is generally believed that the skin damage induced by UV irradiation is a consequence of generation of reactive oxygen species (ROS). Recently, there is an increased interest in the use of natural products as chemopreventive agents for non-melanoma skin cancer (NMSC) due to their antioxidants and anti-inflammatory properties. Quercitrin, glycosylated form of quercetin, is the most common flavonoid in nature with antioxidant properties. The present study investigated the possible beneficial effects of quercitrin to inhibit UVB irradiation-induced oxidative damage in vitro and in vivo. Our results showed that quercitrin decreased ROS generation induced by UVB irradiation in JB6 cells. Quercitrin restored catalase expression and GSH/GSSG ratio reduced by UVB exposure, two major antioxidant enzymes, leading to reductions of oxidative DNA damage and apoptosis and protection of the skin from inflammation caused by UVB exposure. The present study demonstrated that quercitrin functions as an antioxidant against UVB irradiation-induced oxidative damage to skin. - Highlights: • Oxidative stress plays a key role in UV-induced cell and tissue injuries. • Quercitrin decreases ROS generation and restores antioxidants irradiated by UVB. • Quercitrin reduces UVB-irradiated oxidative DNA damage, apoptosis, and inflammation. • Quercitrin functions as an antioxidant against UVB-induced skin injuries.

  4. Quercitrin protects skin from UVB-induced oxidative damage

    International Nuclear Information System (INIS)

    Yin, Yuanqin; Li, Wenqi; Son, Young-Ok; Sun, Lijuan; Lu, Jian; Kim, Donghern; Wang, Xin; Yao, Hua; Wang, Lei; Pratheeshkumar, Poyil; Hitron, Andrew J.; Luo, Jia; Gao, Ning; Shi, Xianglin; Zhang, Zhuo

    2013-01-01

    Exposure of the skin to ultraviolet B (UVB) radiation causes oxidative damage to skin, resulting in sunburn, photoaging, and skin cancer. It is generally believed that the skin damage induced by UV irradiation is a consequence of generation of reactive oxygen species (ROS). Recently, there is an increased interest in the use of natural products as chemopreventive agents for non-melanoma skin cancer (NMSC) due to their antioxidants and anti-inflammatory properties. Quercitrin, glycosylated form of quercetin, is the most common flavonoid in nature with antioxidant properties. The present study investigated the possible beneficial effects of quercitrin to inhibit UVB irradiation-induced oxidative damage in vitro and in vivo. Our results showed that quercitrin decreased ROS generation induced by UVB irradiation in JB6 cells. Quercitrin restored catalase expression and GSH/GSSG ratio reduced by UVB exposure, two major antioxidant enzymes, leading to reductions of oxidative DNA damage and apoptosis and protection of the skin from inflammation caused by UVB exposure. The present study demonstrated that quercitrin functions as an antioxidant against UVB irradiation-induced oxidative damage to skin. - Highlights: • Oxidative stress plays a key role in UV-induced cell and tissue injuries. • Quercitrin decreases ROS generation and restores antioxidants irradiated by UVB. • Quercitrin reduces UVB-irradiated oxidative DNA damage, apoptosis, and inflammation. • Quercitrin functions as an antioxidant against UVB-induced skin injuries

  5. Potent effects of alkaloid-rich extract from Huperzia selago against sodium nitroprusside-evoked PC12 cells damage via attenuation of oxidative stress and apoptosis

    Directory of Open Access Journals (Sweden)

    Anna Magdalena Lenkiewicz

    2016-06-01

    Full Text Available Imbalance between production and scavenging of free radicals and other reactive oxygen species (ROS is a component of many diseases, but it is especially important in aging-related diseases of the central nervous system. Oxidative stress-induced neuronal dysfunction plays an important role in the pathomechanism of neurodegenerative disorders, including Alzheimer’s and Parkinson’s disease. Experimental data showed that free radical scavengers may protect the brain against oxidative modifications. The need for efficient and safe antioxidants with therapeutic potential stimulated the rise of interest in the medicinal plant products, which are a rich source of phytochemicals possessing biological activity. In our studies we focused on alkaloid fractions (AFs isolated from club moss, Huperzia selago and Diphasiastrum complanatum, due to their beneficial activity and exclusive chemical structure. Our previous study demonstrated that selected alkaloids from Huperzia selago effectively protect macromolecules from oxidative damage. Therefore, in the present study we investigated the effects and mechanisms of action of AFs isolated from Huperzia selago and Diphasiastrum complanatum against sodium nitroprusside (SNP-induced oxidative injury in PC12 cells. The results demonstrated that the selected AFs via reduction of nitric oxide (NO liberation protected cells against oxidative stress, DNA and mitochondrial damage, as well as apoptosis caused by SNP. Selected AF notably decreased SNP-evoked mitochondrial polymerase γ (Polg up-regulation. Furthermore, AF which contains Lycopodine, Serratidine, Lycoposerramine-G and (probably Cermizine B completely inhibited the SNP-induced expression of interferon-γ (Ifng and cyclooxygenase 2 (Ptgs2 as well as significantly down-regulated the expression of 12/15-lipoxygenase (Alox12 and tended to decrease the mRNA level of interleukin-6 gene (Il6. In conclusion, these results suggest that the AFs from Huperzia selago

  6. Scavenging capacity of medicinal plants against free radical-induced cellular damage by radiation and photoactivation

    Energy Technology Data Exchange (ETDEWEB)

    Gadkar, Shalaka [Ruia College, Mumbai (India); Mohan, H [Chemistry Group, Bhabha Atomic Research Centre, Mumbai (India); Kamat, J P [Radiation Biology and Health Science Division, Bhabha Atomic Research Centre, Mumbai (India)

    2004-01-01

    The scavenging capacity of medicinal plants. Andrographis paniculata (Ap) and Swertia chirata (Sc) was examined against cellular damage, induced by radiation and photo-activation in sub-cellular membranes. The results demonstrated significant radical scavenging capacity of the extracts. The rate constants as evaluated by deoxyribose degradation studies and the pulse radiolysis studies carried in presence of ABTS radical well supported the antioxidant properties of the extracts. (author)

  7. Three job stress models/concepts and oxidative DNA damage in a sample of workers in Japan.

    Science.gov (United States)

    Inoue, Akiomi; Kawakami, Norito; Ishizaki, Masao; Tabata, Masaji; Tsuchiya, Masao; Akiyama, Miki; Kitazume, Akiko; Kuroda, Mitsuyo; Shimazu, Akihito

    2009-04-01

    Three job stress models/concepts (the job demands-control [DC] model, the effort-reward imbalance [ERI] model, and organizational justice) have been linked to coronary heart disease (CHD) at work. In recent years, oxidative DNA damage has been identified as a new risk factor for CHD. However, evidence for the association between these job stressors and oxidative DNA damage is limited. The present cross-sectional study investigated the association between these job stress models/concepts and oxidative DNA damage as a possible mediator of the adverse health effects of job stress. A total of 166 male and 51 female workers of a manufacturing factory in Japan were surveyed using a mailed questionnaire regarding job stressors and demographic, occupational, and lifestyle variables. Urinary concentrations of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a biomarker of oxidative DNA damage, were also measured. In male subjects, the urinary concentrations of 8-OHdG were significantly higher among the group with lower interactional justice, one of the two components of organizational justice; however, no association was observed with the DC model or the ERI model. In female subjects, high job demands/control ratio was significantly and positively associated with the urinary concentrations of 8-OHdG. Interactional justice among male workers and the DC model-based strain among female workers may be associated with increased urinary concentrations of 8-OHdG which possibly reflects oxidative DNA damage.

  8. DPPH and oxygen free radicals as pro-oxidant of biomolecules.

    Science.gov (United States)

    Letelier, María Eugenia; Molina-Berríos, Alfredo; Cortés-Troncoso, Juan; Jara-Sandoval, José; Holst, Marianne; Palma, Karina; Montoya, Margarita; Miranda, Dante; González-Lira, Víctor

    2008-03-01

    Numerous investigations exist about the alterations that oxygen free radicals can provoke on biomolecules; these modifications can be prevented and/or reversed by different antioxidants agents. On the other hand, 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), a stable nitrogen synthetic radical, is used to evaluate the antioxidant capacity of medicinal herbal products; however, the structural changes that this radical provoke on the herbal active principles are not clear yet. In this work, we compared the redox reactivity of oxygen free radicals and DPPH radical on phospholipids and protein thiol groups present in rat liver microsomes. Cu2+/ascorbate was used as generator system of oxygen free radical and as antioxidant, an extract of Buddleja globosa's leaves. Cu2+/ascorbate provoked microsomal lipid peroxidation, microsomal thiols oxidation and oxygen consumption; all of these phenomena were inhibited by B. globosa extract. On the other hand, DPPH was bleached in different extension by the herbal extract and phosphatidyl choline; beside, DPPH decreased microsomal thiols content, but this phenomenon were not prevented by the herbal extract. Furthermore, DPPH did not induce oxygen consumption and neither modified the oxygen consumption induced by Cu2+/ascorbate. Distinct redox mechanisms may explain the differences between the reactivity of DPPH and oxygen free radicals on biomolecules, which is discussed.

  9. Protein oxidation and peroxidation

    DEFF Research Database (Denmark)

    Davies, Michael Jonathan

    2016-01-01

    Proteins are major targets for radicals and two-electron oxidants in biological systems due to their abundance and high rate constants for reaction. With highly reactive radicals damage occurs at multiple side-chain and backbone sites. Less reactive species show greater selectivity with regard...... to the residues targeted and their spatial location. Modification can result in increased side-chain hydrophilicity, side-chain and backbone fragmentation, aggregation via covalent cross-linking or hydrophobic interactions, protein unfolding and altered conformation, altered interactions with biological partners...... and modified turnover. In the presence of O2, high yields of peroxyl radicals and peroxides (protein peroxidation) are formed; the latter account for up to 70% of the initial oxidant flux. Protein peroxides can oxidize both proteins and other targets. One-electron reduction results in additional radicals...

  10. Aging and oxidatively damaged nuclear DNA in animal organs

    DEFF Research Database (Denmark)

    Møller, Peter; Løhr, Mille; Folkmann, Janne K

    2010-01-01

    Oxidative stress is considered to contribute to aging and is associated with the generation of oxidatively damaged DNA, including 8-oxo-7,8-dihydroguanine. We have identified 69 studies that have measured the level of oxidatively damaged DNA in organs of animals at various ages. In general, organs...... with limited cell proliferation, i.e., liver, kidney, brain, heart, pancreas, and muscle, tended to show accumulation of DNA damage with age, whereas organs with highly proliferating cells, such as intestine, spleen, and testis, showed more equivocal or no effect of age. A restricted analysis of studies...... evidence for aging-associated accumulation of oxidatively damaged DNA in organs with limited cell proliferation....

  11. Astaxanthin Attenuates Homocysteine-Induced Cardiotoxicity in Vitro and in Vivo by Inhibiting Mitochondrial Dysfunction and Oxidative Damage

    Directory of Open Access Journals (Sweden)

    Cun-dong Fan

    2017-12-01

    Full Text Available Homocysteine (Hcy as an independent risk factor contributes to the occurrence and development of human cardiovascular diseases (CVD. Induction of oxidative stress and apoptosis was commonly accepted as the major mechanism in Hcy-induced cardiotoxicity. Astaxanthin (ATX as one of the most powerful antioxidants exhibits novel cardioprotective potential against Hcy-induced endothelial dysfunction. However, the protective effect and mechanism of ATX against Hcy-induced cardiotoxicity in cardiomyocytes have not been elucidated yet. Herein, H9c2 rat cardiomyocytes and Hcy-injured animal model were employed in the present study. The MTT, flow cytometry analysis (FCM, TUNEL-DAPI and western blotting results all demonstrated that ATX significantly alleviated Hcy-induced cytotoxicity in H9c2 cells through inhibition of mitochondria-mediated apoptosis. The JC-1 and Mito-tracker staining both revealed that ATX pre-treatment blocked Hcy-induced mitochondrial dysfunction by regulating Bcl-2 family expression. Moreover, DCFH-DA and Mito-SOX staining showed that ATX effectively attenuated Hcy-induced oxidative damage via scavenging intracellular reactive oxygen species (ROS. Importantly, the ELISA and immunohistochemical results indicated that Hcy-induced cardiotoxicity in vivo was also significantly inhibited by ATX through inhibition of oxidative damage and apoptosis, and improvement of the angiogenesis. Taken together, our results demonstrated that ATX suppressed Hcy-induced cardiotoxicity in vitro and in vivo by inhibiting mitochondrial dysfunction and oxidative damage. Our findings validated the strategy of using ATX may be a highly efficient way to combat Hcy-mediated human CVD.

  12. Astaxanthin Attenuates Homocysteine-Induced Cardiotoxicity in Vitro and in Vivo by Inhibiting Mitochondrial Dysfunction and Oxidative Damage.

    Science.gov (United States)

    Fan, Cun-Dong; Sun, Jing-Yi; Fu, Xiao-Ting; Hou, Ya-Jun; Li, Yuan; Yang, Ming-Feng; Fu, Xiao-Yan; Sun, Bao-Liang

    2017-01-01

    Homocysteine (Hcy) as an independent risk factor contributes to the occurrence and development of human cardiovascular diseases (CVD). Induction of oxidative stress and apoptosis was commonly accepted as the major mechanism in Hcy-induced cardiotoxicity. Astaxanthin (ATX) as one of the most powerful antioxidants exhibits novel cardioprotective potential against Hcy-induced endothelial dysfunction. However, the protective effect and mechanism of ATX against Hcy-induced cardiotoxicity in cardiomyocytes have not been elucidated yet. Herein, H9c2 rat cardiomyocytes and Hcy-injured animal model were employed in the present study. The MTT, flow cytometry analysis (FCM), TUNEL-DAPI and western blotting results all demonstrated that ATX significantly alleviated Hcy-induced cytotoxicity in H9c2 cells through inhibition of mitochondria-mediated apoptosis. The JC-1 and Mito-tracker staining both revealed that ATX pre-treatment blocked Hcy-induced mitochondrial dysfunction by regulating Bcl-2 family expression. Moreover, DCFH-DA and Mito-SOX staining showed that ATX effectively attenuated Hcy-induced oxidative damage via scavenging intracellular reactive oxygen species (ROS). Importantly, the ELISA and immunohistochemical results indicated that Hcy-induced cardiotoxicity in vivo was also significantly inhibited by ATX through inhibition of oxidative damage and apoptosis, and improvement of the angiogenesis. Taken together, our results demonstrated that ATX suppressed Hcy-induced cardiotoxicity in vitro and in vivo by inhibiting mitochondrial dysfunction and oxidative damage. Our findings validated the strategy of using ATX may be a highly efficient way to combat Hcy-mediated human CVD.

  13. Generation and photosensitization properties of the oxidized radical of riboflavin: a laser flash photolysis study

    International Nuclear Information System (INIS)

    Han Zhenhui; Lu Changyuan; Wang Wenfeng; Lin Weizhen; Yao Side; Lin Nianyun

    2000-01-01

    Direct excitation of riboflavin with 248 nm laser gives rise to a transient absorption spectrum with contributions from (1) oxidized radical, (2) hydrated electron, (3) triplet state and reduced radical, and distinction between the transient species below 360 nm is difficult for the absorption overlapped. The RF ·+ or RF(-H) · has been clearly produced via direct photoionization by 248 nm laser in aqueous solution, which has been unambiguously identified by SO 4 ·- radical oxidation, although its transient absorption can not be observed clearly for both lower absorption coefficient (ε = 2000 dm 3 mol -1 cm -1 at 640 nm at pH 7.1) and overlap from others. In the present paper, electron transfer from purine and pyrimidine nucleotides to one-electron oxidized radical of riboflavin were observed for the first time in aqueous solution, and the reaction rate constants were determined respectively, which would obviously be of considerable significance in vivo and in vitro. The results clearly demonstrate the importance of oxidized radical of riboflavin in flavin photochemistry and photobiology. These reaction paths are important for the elucidation of the interaction between riboflavin and DNA nucleotides under photoexcitation. When riboflavin was excited, triplet state and oxidized radical can be formed directly or by sequence reactions of triplet state. In the presence of DNA, electron transfer can take place to form a base radical cation, then hole migration to GG step along base-stacking of DNA leads to DNA strand scission, which has been verified by many steady product analysis. This selective cleavage of DNA shows the potential application of riboflavin as a site-specify photonuclease, which has become a highlight' in the currently photochemistry, photomedicine and photobiology areas. The mechanism implies that riboflavin can be applied potentially to photosensitization of oxygen deficient or under high intensity pulsed laser irradiation. (author)

  14. One-electron oxidation reactions of purine and pyrimidine bases in cellular DNA.

    Science.gov (United States)

    Cadet, Jean; Wagner, J Richard; Shafirovich, Vladimir; Geacintov, Nicholas E

    2014-06-01

    The aim of this survey is to critically review the available information on one-electron oxidation reactions of nucleobases in cellular DNA with emphasis on damage induced through the transient generation of purine and pyrimidine radical cations. Since the indirect effect of ionizing radiation mediated by hydroxyl radical is predominant in cells, efforts have been made to selectively ionize bases using suitable one-electron oxidants that consist among others of high intensity UVC laser pulses. Thus, the main oxidation product in cellular DNA was found to be 8-oxo-7,8-dihydroguanine as a result of direct bi-photonic ionization of guanine bases and indirect formation of guanine radical cations through hole transfer reactions from other base radical cations. The formation of 8-oxo-7,8-dihydroguanine and other purine and pyrimidine degradation products was rationalized in terms of the initial generation of related radical cations followed by either hydration or deprotonation reactions in agreement with mechanistic pathways inferred from detailed mechanistic studies. The guanine radical cation has been shown to be implicated in three other nucleophilic additions that give rise to DNA-protein and DNA-DNA cross-links in model systems. Evidence was recently provided for the occurrence of these three reactions in cellular DNA. There is growing evidence that one-electron oxidation reactions of nucleobases whose mechanisms have been characterized in model studies involving aqueous solutions take place in a similar way in cells. It may also be pointed out that the above cross-linked lesions are only produced from the guanine radical cation and may be considered as diagnostic products of the direct effect of ionizing radiation.

  15. Cholesterol Hydroperoxide Generation, Translocation, and Reductive Turnover in Biological Systems.

    Science.gov (United States)

    Girotti, Albert W; Korytowski, Witold

    2017-12-01

    Cholesterol is like other unsaturated lipids in being susceptible to peroxidative degradation upon exposure to strong oxidants like hydroxyl radical or peroxynitrite generated under conditions of oxidative stress. In the eukaryotic cell plasma membrane, where most of the cellular cholesterol resides, peroxidation leads to membrane structural and functional damage from which pathological states may arise. In low density lipoprotein, cholesterol and phospholipid peroxidation have long been associated with atherogenesis. Among the many intermediates/products of cholesterol oxidation, hydroperoxide species (ChOOHs) have a number of different fates and deserve special attention. These fates include (a) damage-enhancement via iron-catalyzed one-electron reduction, (b) damage containment via two-electron reduction, and (c) inter-membrane, inter-lipoprotein, and membrane-lipoprotein translocation, which allows dissemination of one-electron damage or off-site suppression thereof depending on antioxidant location and capacity. In addition, ChOOHs can serve as reliable and conveniently detected mechanistic reporters of free radical-mediated reactions vs. non-radical (e.g., singlet oxygen)-mediated reactions. Iron-stimulated peroxidation of cholesterol and other lipids underlies a newly discovered form of regulated cell death called ferroptosis. These and other deleterious consequences of radical-mediated lipid peroxidation will be discussed in this review.

  16. Free radical reaction characteristics of coal low-temperature oxidation and its inhibition method.

    Science.gov (United States)

    Li, Zenghua; Kong, Biao; Wei, Aizhu; Yang, Yongliang; Zhou, Yinbo; Zhang, Lanzhun

    2016-12-01

    Study on the mechanism of coal spontaneous combustion is significant for controlling fire disasters due to coal spontaneous combustion. The free radical reactions can explain the chemical process of coal at low-temperature oxidation. Electron spin resonance (ESR) spectroscopy was used to measure the change rules of the different sorts and different granularity of coal directly; ESR spectroscopy chart of free radicals following the changes of temperatures was compared by the coal samples applying air and blowing nitrogen, original coal samples, dry coal samples, and demineralized coal samples. The fragmentation process was the key factor of producing and initiating free radical reactions. Oxygen, moisture, and mineral accelerated the free radical reactions. Combination of the free radical reaction mechanism, the mechanical fragmentation leaded to the elevated CO concentration, fracturing of coal pillar was more prone to spontaneous combustion, and spontaneous combustion in goaf accounted for a large proportion of the fire in the mine were explained. The method of added diphenylamine can inhibit the self-oxidation of coal effectively, the action mechanism of diphenylamine was analyzed by free radical chain reaction, and this research can offer new method for the development of new flame retardant.

  17. High basal metabolic rate does not elevate oxidative stress during reproduction in laboratory mice.

    Science.gov (United States)

    Brzęk, Paweł; Książek, Aneta; Ołdakowski, Łukasz; Konarzewski, Marek

    2014-05-01

    Increased oxidative stress (OS) has been suggested as a physiological cost of reproduction. However, previous studies reported ambiguous results, with some even showing a reduction of oxidative damage during reproduction. We tested whether the link between reproduction and OS is mediated by basal metabolic rate (BMR), which has been hypothesized to affect both the rate of radical oxygen species production and antioxidative capacity. We studied the effect of reproduction on OS in females of laboratory mice divergently selected for high (H-BMR) and low (L-BMR) BMR, previously shown to differ with respect to parental investment. Non-reproducing L-BMR females showed higher oxidative damage to lipids (quantified as the level of malondialdehyde in internal organ tissues) and DNA (quantified as the level of 8-oxodG in blood serum) than H-BMR females. Reproduction did not affect oxidative damage to lipids in either line; however, it reduced damage to DNA in L-BMR females. Reproduction increased catalase activity in liver (significantly stronger in L-BMR females) and decreased it in kidneys. We conclude that the effect of reproduction on OS depends on the initial variation in BMR and varies between studied internal organs and markers of OS.

  18. Anti-radical power gives insight into early lipid oxidation events during frying

    NARCIS (Netherlands)

    Loon, W.A.M.; Linssen, J.P.H.; Legger, A.; Voragen, A.G.J.

    2006-01-01

    The aim of this research was to use anti-radical power (ARP) to study early lipid oxidation events during frying. The 2,2-diphenyl-1-picrylhydrazyl radical (DPPH¿) test was used to determine the ARP. As oil does not dissolve completely in methanol, which is generally used for the DPPH¿ test, butanol

  19. Toward unfolding the prion misfolding mystery: protein free radical chemistry in transmissible spongiform encephalopathies

    International Nuclear Information System (INIS)

    Yang Chiming

    2003-01-01

    Owing to the high oxygen-respiration in the brain of mammals, oxidative damage to prion protein has been suggested to be an additional factor. A large body of intriguing features of scrapie and prion diseases have provided multiple lines of indirect chemistry evidence, suggesting that the infectious agents may be putative forms of sequence-specific prion radicals (SSPR) and/or their immediate precursors in the transmissible spongiform encephalopathies (TSE). Here a molecular mechanism corresponding to the self-replication of scrapie protein mediated by prion free-radical processes, consonant with 'protein-only' hypotheses is proposed. This new theory may not only aid our understanding of the occurrence of prions, but also provides new insight into the possible chemistry principles underlying the neutrodegenerative disorders. It is anticipated that future studies based on this suggestion and chemistry principles of genetic diseases may allow us to determine an effective approach to stop mad cow disease and its human version, new variant of Creutzfeldt-Jakob disease (v CJD)

  20. Dicranostiga leptopodu (Maxim.) Fedde extracts attenuated CCl4-induced acute liver damage in mice through increasing anti-oxidative enzyme activity to improve mitochondrial function.

    Science.gov (United States)

    Tang, Deping; Wang, Fang; Tang, Jinzhou; Mao, Aihong; Liao, Shiqi; Wang, Qin

    2017-01-01

    Dicranostiga Leptodu (Maxim.) fedde (DLF), a poppy plant, has been reported have many benefits and medicinal properties, including free radicals scavenging and detoxifying. However, the protective effect of DLF extracts against carbon tetrachloride (CCl 4 )-induced damage in mice liver has not been elucidated. Here, we demonstrated that DLF extracts attenuated CCl 4 -induced liver damage in mice through increasing anti-oxidative enzyme activity to improve mitochondrial function. In this study, the mice liver damage evoked by CCl 4 was marked by morphology changes, significant rise in lipid peroxidation, as well as alterations of mitochondrial respiratory function. Interestingly, pretreatment with DLF extracts attenuated CCl 4 -induced morphological damage and increasing of lipid peroxidation in mice liver. Additionally, DLF extracts improved mitochondrial function by preventing the disruption of respiratory chain and suppression of mitochondrial Na + K + -ATPase and Ca 2+ -ATPase activity. Furthermore, administration with DLF extracts elevated superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) levels and maintained the balance of redox status. This results showed that toxic protection effect of DLF extracts on mice liver is mediated by improving mitochondrial respiratory function and keeping the balance of redox status, which suggesting that DLF extracts could be used as potential toxic protection agent for the liver against hepatotoxic agent. Copyright © 2016. Published by Elsevier Masson SAS.

  1. Can Carbamates Undergo Radical Oxidation in the Soil Environment? A Case Study on Carbaryl and Carbofuran.

    Science.gov (United States)

    Ćwieląg-Piasecka, Irmina; Witwicki, Maciej; Jerzykiewicz, Maria; Jezierska, Julia

    2017-12-19

    Radical oxidation of carbamate insecticides, namely carbaryl and carbofuran, was investigated with spectroscopic (electron paramagnetic resonance [EPR] and UV-vis) and theoretical (density functional theory [DFT] and ab initio orbital-optimized spin-component scaled MP2 [OO-SCS-MP2]) methods. The two carbamates were subjected to reaction with • OH, persistent DPPH • and galvinoxyl radical, as well as indigenous radicals of humic acids. The influence of fulvic acids on carbamate oxidation was also tested. The results obtained with EPR and UV-vis spectroscopy indicate that carbamates can undergo direct reactions with various radical species, oxidizing themselves into radicals in the process. Hence, they are prone to participate in the prolongation step of the radical chain reactions occurring in the soil environment. Theoretical calculations revealed that from the thermodynamic point of view hydrogen atom transfer is the preferred mechanism in the reactions of the two carbamates with the radicals. The activity of carbofuran was determined experimentally (using pseudo-first-order kinetics) and theoretically to be noticeably higher in comparison with carbaryl and comparable with gallic acid. The findings of this study suggest that the radicals present in soil can play an important role in natural remediation mechanisms of carbamates.

  2. Viewing oxidative stress through the lens of oxidative signalling rather than damage.

    Science.gov (United States)

    Foyer, Christine H; Ruban, Alexander V; Noctor, Graham

    2017-03-07

    Concepts of the roles of reactive oxygen species (ROS) in plants and animals have shifted in recent years from focusing on oxidative damage effects to the current view of ROS as universal signalling metabolites. Rather than having two opposing activities, i.e. damage and signalling, the emerging concept is that all types of oxidative modification/damage are involved in signalling, not least in the induction of repair processes. Examining the multifaceted roles of ROS as crucial cellular signals, we highlight as an example the loss of photosystem II function called photoinhibition, where photoprotection has classically been conflated with oxidative damage. © 2017 The Author(s). This is an open access article published by Portland Press Limited on behalf of the Biochemical Society and distributed under the Creative Commons Attribution Licence 4.0 (CC BY).

  3. Free radicals in biology. Volume II

    International Nuclear Information System (INIS)

    Pryor, W.A.

    1976-01-01

    This volume continues the treatment of topics in free radical biology and free radical pathology from Volume I. In the first chapter, pyridinyl radicals, radicals which are models for those derived from NAD, are discussed. Pyridinyl radicals can be synthesized and isolated and directly studied in a number of chemical systems. The next chapter treats the role of glutathione in the cell. It is becoming even more apparent that this vital thiol controls a large number of important cellular functions. The GSH/GSSG balance has recently been implicated as a control for cellular development; this balance also may be important in relaying the effects of oxidants from one site to another in the body. The next chapter outlines the reactions of singlet oxygen; some of these involve free radicals and some do not. This reactive intermediate appears to be important both in photochemical smog and in cellular chemistry where singlet oxygen is produced by nonphotochemical processes. The production of free radicals from dry tissues, a controversial area with conflicting claims is reviewed. The next chapter outlines the current status of the studies of photochemical smog. The next two chapters treat specific reactive materials which are present in smog. The first discusses the chemistry of nitrogen oxides and ozone. The second chapter treats the chemistry of the peroxyacyl nitrites. These compounds, although present in only small concentration, are among the most toxic components of smog. The last two chapters treat radiation damage to proteins and radiation protection and radical reactions produced by radiation in nucleic acids

  4. Physiology of free radicals

    Directory of Open Access Journals (Sweden)

    Stevanović Jelka

    2011-01-01

    Full Text Available Free radicals imply that every atom, molecule, ion, group of atoms, or molecules with one or several non-paired electrons in outer orbital. Among these are: nitrogenoxide (NO•, superoxide-anion-radical (O2•-, hydroxyl radical (OH•, peroxyl radical (ROO•, alcoxyl radical (RO• and hydroperoxyl radical (HO2•. However, reactive oxygen species also include components without non-paired electrons in outer orbital (so-called reactive non-radical agents, such as: singlet oxygen (1O2, peroxynitrite (ONOO-, hydrogen-peroxide (H2O2, hypochloric acid (eg. HOCl and ozone (O3. High concentrations of free radicals lead to the development of oxidative stress which is a precondition for numerous pathological effects. However, low and moderate concentrations of these matter, which occur quite normally during cell metabolic activity, play multiple significant roles in many reactions. Some of these are: regulation of signal pathways within the cell and between cells, the role of chemoattractors and leukocyte activators, the role in phagocytosis, participation in maintaining, changes in the position and shape of the cell, assisting the cell during adaption and recovery from damage (e.g.caused by physical effort, the role in normal cell growth, programmed cell death (apoptosis and cell ageing, in the synthesis of essential biological compounds and energy production, as well as the contribution to the regulation of the vascular tone, actually, tissue vascularization.

  5. Radical-mediated annulation reactions. A versatile strategy for the preparation of a series of carbocycles.

    Science.gov (United States)

    Sibi, M P; Chen, J; Rheault, T R

    2001-11-15

    [reaction--see text] A series of novel 6-endo [4 + 2] and 7-endo [5 + 2] radical-mediated annulation reactions are described. These annulation sequences involve an intermolecular radical addition followed by intramolecular trapping with an allyltin moiety incorporated into the radical precursor fragment. This methodology allows for access to functionalized 6- and 7-membered carbocycles as well as bicyclic compounds with good to excellent levels of stereocontrol.

  6. Ionizing radiation, antioxidant response and oxidative damage: A meta-analysis

    Energy Technology Data Exchange (ETDEWEB)

    Einor, D., E-mail: daniel@einor.com [Department of Biological Sciences, University of South Carolina, Columbia, SC 29208 (United States); Bonisoli-Alquati, A., E-mail: andreabonisoli@gmail.com [Department of Biological Sciences, University of South Carolina, Columbia, SC 29208 (United States); School of Renewable Natural Resources, Louisiana State University AgCenter, Baton Rouge, LA 70803 (United States); Costantini, D., E-mail: davidcostantini@libero.it [Department of Biology, University of Antwerp, Wilrijk, B-2610, Antwerp (Belgium); Mousseau, T.A., E-mail: mousseau@sc.edu [Department of Biological Sciences, University of South Carolina, Columbia, SC 29208 (United States); Faculty of Bioscience and Biotechnology, Chubu University, Kasugai (Japan); Møller, A.P., E-mail: anders.moller@u-psud.fr [Laboratoire d' Ecologie, Systématique et Evolution, CNRS UMR 8079, Université Paris-Sud, Bâtiment 362, F-91405 Orsay Cedex (France)

    2016-04-01

    One mechanism proposed as a link between exposure to ionizing radiation and detrimental effects on organisms is oxidative damage. To test this hypothesis, we surveyed the scientific literature on the effects of chronic low-dose ionizing radiation (LDIR) on antioxidant responses and oxidative damage. We found 40 publications and 212 effect sizes for antioxidant responses and 288 effect sizes for effects of oxidative damage. We performed a meta-analysis of signed and unsigned effect sizes. We found large unsigned effects for both categories (0.918 for oxidative damage; 0.973 for antioxidant response). Mean signed effect size weighted by sample size was 0.276 for oxidative damage and − 0.350 for antioxidant defenses, with significant heterogeneity among effects for both categories, implying that ionizing radiation caused small to intermediate increases in oxidative damage and small to intermediate decreases in antioxidant defenses. Our estimates are robust, as shown by very high fail-safe numbers. Species, biological matrix (tissue, blood, sperm) and age predicted the magnitude of effects for oxidative damage as well as antioxidant response. Meta-regression models showed that effect sizes for oxidative damage varied among species and age classes, while effect sizes for antioxidant responses varied among species and biological matrices. Our results are consistent with the description of mechanisms underlying pathological effects of chronic exposure to LDIR. Our results also highlight the importance of resistance to oxidative stress as one possible mechanism associated with variation in species responses to LDIR-contaminated areas. - Highlights: • There is interest in variation in metabolic effects of chronic low-dose ionizing radiation • A random effect meta-analysis of effect sizes of radioactive contamination was performed • We found significant effects of radiation on oxidative damage and antioxidant response • We found significant heterogeneity among

  7. Modification by cystamine of radiation-induced free radical damages to biomolecules in tissues of mouse organs

    International Nuclear Information System (INIS)

    Svistunenko, D.A.; Gudtsova, K.V.

    1989-01-01

    The method of low-temperature ESR-spectroscopy was used to study a modifying effect of cystamine on the yield of radiation-induced free radicals in different biomolecules of liver and spleen tissues of mice. Intraperitoneal administration of cystamine (150 mg/kg) 15 min before isolation and freezing of the tissues was shown to reduce by 11 per cent the yield of radicals of H-adducts of thymine DNA bases, to decrease by 23 per cent the yield of radicals of triacyglycerol and phospholipid radiolysis, and to increase by 24 per cent the yield of radicals of lipid fatty acid residues in splenic tissues. According to the criterion used, cystamine has no modyfying action on the yield of free-radical damages to liver biomolecules

  8. Mechanism of pyrogallol red oxidation induced by free radicals and reactive oxidant species. A kinetic and spectroelectrochemistry study.

    Science.gov (United States)

    Atala, E; Velásquez, G; Vergara, C; Mardones, C; Reyes, J; Tapia, R A; Quina, F; Mendes, M A; Speisky, H; Lissi, E; Ureta-Zañartu, M S; Aspée, A; López-Alarcón, C

    2013-05-02

    Pyrogallol red (PGR) presents high reactivity toward reactive (radical and nonradical) species (RS). This property of PGR, together with its characteristic spectroscopic absorption in the visible region, has allowed developing methodologies aimed at evaluating the antioxidant capacity of foods, beverages, and human fluids. These methods are based on the evaluation of the consumption of PGR induced by RS and its inhibition by antioxidants. However, at present, there are no reports regarding the degradation mechanism of PGR, limiting the extrapolation to how antioxidants behave in different systems comprising different RS. In the present study, we evaluate the kinetics of PGR consumption promoted by different RS (peroxyl radicals, peroxynitrite, nitrogen dioxide, and hypochlorite) using spectroscopic techniques and detection of product by HPLC mass spectrometry. The same pattern of oxidation and spectroscopic properties of the products is observed, independently of the RS employed. Mass analysis indicates the formation of only one product identified as a quinone derivative, excluding the formation of peroxides or hydroperoxides and/or chlorinated compounds, in agreement with FOX's assays and oxygen consumption experiments. Cyclic voltammetry, carried out at different pH's, shows an irreversible oxidation of PGR, indicating the initial formation of a phenoxy radical and a second charge transfer reaction generating an ortho-quinone derivative. Spectroelectrochemical oxidation of PGR shows oxidation products with identical UV-visible absorption properties to those observed in RS-induced oxidation.

  9. Protein capped nanosilver free radical oxidation: role of biomolecule capping on nanoparticle colloidal stability and protein oxidation.

    Science.gov (United States)

    Ahumada, Manuel; Bohne, Cornelia; Oake, Jessy; Alarcon, Emilio I

    2018-05-03

    We studied the effect of human serum albumin protein capped spherical nanosilver on the nanoparticle stability upon peroxyl radical oxidation. The nanoparticle-protein composite is less prone to oxidation compared to the individual components. However, higher concentrations of hydrogen peroxide were formed in the nanoparticle-protein system.

  10. Ionizing radiation, antioxidant response and oxidative damage: A meta-analysis.

    Science.gov (United States)

    Einor, D; Bonisoli-Alquati, A; Costantini, D; Mousseau, T A; Møller, A P

    2016-04-01

    One mechanism proposed as a link between exposure to ionizing radiation and detrimental effects on organisms is oxidative damage. To test this hypothesis, we surveyed the scientific literature on the effects of chronic low-dose ionizing radiation (LDIR) on antioxidant responses and oxidative damage. We found 40 publications and 212 effect sizes for antioxidant responses and 288 effect sizes for effects of oxidative damage. We performed a meta-analysis of signed and unsigned effect sizes. We found large unsigned effects for both categories (0.918 for oxidative damage; 0.973 for antioxidant response). Mean signed effect size weighted by sample size was 0.276 for oxidative damage and -0.350 for antioxidant defenses, with significant heterogeneity among effects for both categories, implying that ionizing radiation caused small to intermediate increases in oxidative damage and small to intermediate decreases in antioxidant defenses. Our estimates are robust, as shown by very high fail-safe numbers. Species, biological matrix (tissue, blood, sperm) and age predicted the magnitude of effects for oxidative damage as well as antioxidant response. Meta-regression models showed that effect sizes for oxidative damage varied among species and age classes, while effect sizes for antioxidant responses varied among species and biological matrices. Our results are consistent with the description of mechanisms underlying pathological effects of chronic exposure to LDIR. Our results also highlight the importance of resistance to oxidative stress as one possible mechanism associated with variation in species responses to LDIR-contaminated areas. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Preventing Ultraviolet Light-Induced Damage: The Benefits of Antioxidants

    Science.gov (United States)

    Yip, Cheng-Wai

    2007-01-01

    Extracts of fruit peels contain antioxidants that protect the bacterium "Escherichia coli" against damage induced by ultraviolet light. Antioxidants neutralise free radicals, thus preventing oxidative damage to cells and deoxyribonucleic acid. A high survival rate of UV-exposed cells was observed when grapefruit or grape peel extract was…

  12. Comparison of Oxidative Stresses Mediated by Different Crystalline Forms and Surface Modification of Titanium Dioxide Nanoparticles

    Directory of Open Access Journals (Sweden)

    Karim Samy El-Said

    2015-01-01

    Full Text Available Titanium dioxide nanoparticles (TiO2 NPs are manufactured worldwide for use in a wide range of applications. There are two common crystalline forms of TiO2 anatase and rutile with different physical and chemical characteristics. We previously demonstrated that an increased DNA damage response is mediated by anatase crystalline form compared to rutile. In the present study, we conjugated TiO2 NPs with polyethylene glycol (PEG in order to reduce the genotoxicity and we evaluated some oxidative stress parameters to obtain information on the cellular mechanisms of DNA damage that operate in response to TiO2 NPs different crystalline forms exposure in hepatocarcinoma cell lines (HepG2. Our results indicated a significant increase in oxidative stress mediated by the anatase form of TiO2 NPs compared to rutile form. On the other hand, PEG modified TiO2 NPs showed a significant decrease in oxidative stress as compared to TiO2 NPs. These data suggested that the genotoxic potential of TiO2 NPs varies with crystalline form and surface modification.

  13. The LEGO toolbox: Supramolecular building blocks by nitroxide-mediated controlled radical polymerization

    NARCIS (Netherlands)

    Lohmeijer, B.G.G.; Schubert, U.S.

    2005-01-01

    A terpyridine-functionalized alkoxyamine unimolecular initiator was used for the nitroxide-mediated controlled living radical polymerization of n-butylacrylate, N,N-dimethylacrylamide, 4-vinylpyridine, 2-vinylpyridine, and isoprene. For the former three monomers, the kinetics were studied. All

  14. Superoxide radical-mediated photocatalytic oxidation of phenolic compounds over Ag"+/TiO_2: Influence of electron donating and withdrawing substituents

    International Nuclear Information System (INIS)

    Xiao, Jiadong; Xie, Yongbing; Han, Qingzhen; Cao, Hongbin; Wang, Yujiao; Nawaz, Faheem; Duan, Feng

    2016-01-01

    Highlights: • A weak EWG benefited photocatalytic oxidation of phenols the most. • Phenolic compounds were dominantly oxidized by ·O_2"−, rather than ·OH, "1O_2 or h"+. • ·O_2"− preferred to nucleophilically attack EDG substituted phenols. • ·O_2"− more likely electrophilically attacked EWG substituted phenols. • ·O_2"− simultaneously nucleophilically and electrophilically assaulted p-chlorophenol. - Abstract: A comparative study was constructed to correlate the electronic property of the substituents with the degradation rates of phenolic compounds and their oxidation pathways under UV with Ag"+/TiO_2 suspensions. It was verified that a weak electron withdrawing substituent benefited photocatalytic oxidation the most, while an adverse impact appeared when a substituent was present with stronger electron donating or withdrawing ability. The addition of p-benzoquinone dramatically blocked the degradation, confirming superoxide radicals (·O_2"−) as the dominant photooxidant, rather than hydroxyl radicals, singlet oxygen or positive holes, which was also independent of the substituent. Hammett relationship was established based on pseudo-first-order reaction kinetics, and it revealed two disparate reaction patterns between ·O_2"− and phenolic compounds, which was further verified by the quantum chemical computation on the frontier molecular orbitals and Mulliken charge distributions of ·O_2"− and phenolic compounds. It was found that electron donating group (EDG) substituted phenols were more likely nucleophilically attacked by ·O_2"−, while ·O_2"− preferred to electrophilically assault electron withdrawing group (EWG) substituted phenols. Exceptionally, electrophilic and nucleophilic attack by ·O_2"− could simultaneously occur in p-chlorophenol degradation, consequently leading to its highest rate constant. Possible reactive positions on the phenolic compounds were also detailedly uncovered.

  15. Increased cerebral output of free radicals during hypoxia: implications for acute mountain sickness?

    DEFF Research Database (Denmark)

    Bailey, Damian M; Taudorf, Sarah; Berg, Ronan M G

    2009-01-01

    This study examined whether hypoxia causes free radical-mediated disruption of the blood-brain barrier (BBB) and impaired cerebral oxidative metabolism and whether this has any bearing on neurological symptoms ascribed to acute mountain sickness (AMS). Ten men provided internal jugular vein...... paramagnetic resonance spectroscopy and ozone-based chemiluminescence were employed for direct detection of spin-trapped free radicals and nitric oxide metabolites. Neuron-specific enolase (NSE), S100beta, and 3-nitrotyrosine (3-NT) were determined by ELISA. Hypoxia increased the arterio-jugular venous...... concentration difference (a-v(D)) and net cerebral output of lipid-derived alkoxyl-alkyl free radicals and lipid hydroperoxides (P

  16. Free radicals and low-level photon emission in human pathogenesis: state of the art.

    Science.gov (United States)

    Van Wijk, Roeland; Van Wijk, Eduard P A; Wiegant, Fred A C; Ives, John

    2008-05-01

    Convincing evidence supports a role for oxidative stress in the pathogenesis of many chronic diseases. The model includes the formation of radical oxygen species (ROS) and the misassembly and aggregation of proteins when three tiers of cellular defence are insufficient: (a) direct antioxidative systems, (b) molecular damage repairing systems, and (c) compensatory chaperone synthesis. The aim of the present overview is to introduce (a) the basics of free radical and antioxidant metabolism, (b) the role of the protein quality control system in protecting cells from free radical damage and its relation to chronic diseases, (c) the basics of the ultraweak luminescence as marker of the oxidant status of biological systems, and (d) the research in human photon emission as a non-invasive marker of oxidant status in relation to chronic diseases. In considering the role of free radicals in disease, both their generation and their control by the antioxidant system are part of the story. Excessive free radical production leads to the production of heat shock proteins and chaperone proteins as a second line of protection against damage. Chaperones at the molecular level facilitate stress regulation vis-à-vis protein quali y control mechanisms. The manifestation of misfolded proteins and aggregates is a hallmark of a range of neurodegenerative disorders including Alzheimer's disease, Parkinson's disease, amylotrophic lateral sclerosis, polyglutamine (polyQ) diseases, diabetes and many others. Each of these disorders exhibits aging-dependent onset and a progressive, usually fatal clinical course. The second part reviews the current status of human photon emission techniques and protocols for recording the human oxidative status. Sensitive photomultiplier tubes may provide a tool for non-invasive and continuous monitoring of oxidative metabolism. In that respect, recording ultraweak luminescence has been favored compared to other indirect assays. Several biological models have

  17. Antioxidant effect of naturally occurring xanthines on the oxidative damage of DNA bases

    International Nuclear Information System (INIS)

    Vieira, A.J.S.C.; Telo, J.P.; Pereira, H.F.; Patrocinio, P.F.; Dias, R.M.B.

    1999-01-01

    The repair of the oxidised radicals of adenine and guanosine by several naturally occurring xanthines was studied. Each pair of DNA purine/xanthine was made to react with the sulphate radical and the decrease of the concentration of both compounds was measured by HPLC as a function of irradiation time. The results show that xanthine efficiently prevents the oxidation of the two DNA purines. Theophylline and para-xanthine repair the oxidizes radical of adenine but not the one from guanosine. Theobromine and caffeine to do not show any protecting effect. An order of the oxidation potentials of all the purines studied is proposed. (authors)

  18. Reconstruction of radical prostatectomy-induced urethral damage using skeletal muscle-derived multipotent stem cells.

    Science.gov (United States)

    Hoshi, Akio; Tamaki, Tetsuro; Tono, Kayoko; Okada, Yoshinori; Akatsuka, Akira; Usui, Yukio; Terachi, Toshiro

    2008-06-15

    Postoperative damage of the urethral rhabdosphincter (URS) and neurovascular bundle (NVB) is a major operative complication of radical prostatectomy. It is generally recognized to be caused by unavoidable surgical damage to the muscle-nerve-blood vessel units around the urethra. We attempted to treat this damage using skeletal muscle-derived stem cells, which are able to reconstitute muscle-nerve-blood vessel units. Cells were enzymatically extracted and sorted by flow cytometry as CD34/45 (Sk-34) and CD34/45 (Sk-DN) cells from green fluorescent protein transgenic mice and rats. URS-NVB damage was induced by manually removing one-third of the total URS and unilateral invasion of NVB in wild-type Sprague-Dawley and node rats. Freshly isolated Sk-34, Sk-34+Sk-DN cells, and cultured Sk-DN cells were directly transplanted into the damaged portion. At 4 and 12 weeks after transplantation, urethral pressure profile by electrical stimulation through the sacral surface (L6-S1) was evaluated as functional recovery. The recovery ratio in the control and transplanted groups was 37.6% and 72.9%, at 4 weeks, and 41.6% and 78.4% at 12 weeks, respectively (Pcells differentiated into numerous skeletal muscle fibers having neuromuscular junctions (innervation) and nerve bundle-related Schwann cells and perineurium, and blood vessel-related endothelial cells and pericyte around the urethra. Thus, we conclude that transplantation of skeletal muscle-derived multipotent Sk-34 and Sk-DN cells is potentially useful for the reconstitution of postoperative damage of URS and NVB after radical prostatectomy.

  19. Free radical injury in skin cultured fibroblasts from Alzheimer's disease patients.

    Science.gov (United States)

    Tesco, G; Latorraca, S; Piersanti, P; Sorbi, S; Piacentini, S; Amaducci, L

    1992-12-26

    Oxygen radical production is postulated to be a major cause of cell damage in aging. We have studied the response to toxic oxygen metabolites of fibroblast cell lines derived from skin biopsies of patients with familial and sporadic Alzheimer's disease compared with those derived from normal controls. Fibroblasts were damaged by the generation of oxygen metabolites during the enzymatic oxidation of acetaldehyde by 50 mU of xanthine-oxidase. To quantify cell damage we measured lactate dehydrogenase activity in the culture medium and cell viability in fibroblast cultures from four normal subjects, five FAD, and four AD patients after 2 hours of Xo incubation. We found a significant increase of LDH activity in FAD vs. controls and also in AD vs. controls, suggesting that AD cells are more susceptible to oxygen radical damage than are normal controls.

  20. Consecutive dynamic resolutions of phosphine oxides

    NARCIS (Netherlands)

    Kortmann, Felix A.; Chang, Mu-Chieh; Otten, Edwin; Couzijn, Erik P. A.; Lutz, Martin; Minnaard, Adriaan J.

    2013-01-01

    A crystallization-induced asymmetric transformation (CIAT) involving a radical-mediated racemization provides access to enantiopure secondary phosphine oxides. A consecutive CIAT is used to prepare enantio-and diastereo-pure tert-butyl(hydroxyalkyl)phenylphosphine oxides.

  1. The Role of Free Radicals in the Aging Brain and Parkinson’s Disease: Convergence and Parallelism

    Directory of Open Access Journals (Sweden)

    Dong-Kug Choi

    2012-08-01

    Full Text Available Free radical production and their targeted action on biomolecules have roles in aging and age-related disorders such as Parkinson’s disease (PD. There is an age-associated increase in oxidative damage to the brain, and aging is considered a risk factor for PD. Dopaminergic neurons show linear fallout of 5–10% per decade with aging; however, the rate and intensity of neuronal loss in patients with PD is more marked than that of aging. Here, we enumerate the common link between aging and PD at the cellular level with special reference to oxidative damage caused by free radicals. Oxidative damage includes mitochondrial dysfunction, dopamine auto-oxidation, α-synuclein aggregation, glial cell activation, alterations in calcium signaling, and excess free iron. Moreover, neurons encounter more oxidative stress as a counteracting mechanism with advancing age does not function properly. Alterations in transcriptional activity of various pathways, including nuclear factor erythroid 2-related factor 2, glycogen synthase kinase 3β, mitogen activated protein kinase, nuclear factor kappa B, and reduced activity of superoxide dismutase, catalase and glutathione with aging might be correlated with the increased incidence of PD.

  2. [Research progress on free radicals in human body].

    Science.gov (United States)

    Wang, Q B; Xu, F P; Wei, C X; Peng, J; Dong, X D

    2016-08-10

    Free radicals are the intermediates of metabolism, widely exist in the human bodies. Under normal circumstances, the free radicals play an important role in the metabolic process on human body, cell signal pathway, gene regulation, induction of cell proliferation and apoptosis, so as to maintain the normal growth and development of human body and to inhibit the growth of bacteria, virus and cancer. However, when organic lesion occurs affected by external factors or when equilibrium of the free radicals is tipped in the human body, the free radicals will respond integratedly with lipids, protein or nucleic acid which may jeopardize the health of human bodies. This paper summarizes the research progress of the free radicals conducted in recent years, in relations to the perspective of the types, origins, test methods of the free radicals and their relationship with human's health. In addition, the possible mechanisms of environmental pollutants (such as polycyclic aromatic hydrocarbons) mediating oxidative stress and free radicals scavenging in the body were also summarized.

  3. Markers of protein oxidation

    DEFF Research Database (Denmark)

    Headlam, Henrietta A; Davies, Michael Jonathan

    2004-01-01

    Exposure of proteins to radicals in the presence of O2 gives both side-chain oxidation and backbone fragmentation. These processes can be interrelated, with initial side-chain oxidation giving rise to backbone damage via transfer reactions. We have shown previously that alkoxyl radicals formed...... of this process depends on the extent of oxidation at C-3 compared with other sites. HO*, generated by gamma radiolysis, gave the highest total carbonyl yield, with protein-bound carbonyls predominating over released. In contrast, metal ion/H2O2 systems, gave more released than bound carbonyls, with this ratio...... modulated by EDTA. This is ascribed to metal ion-protein interactions affecting the sites of initial oxidation. Hypochlorous acid gave low concentrations of released carbonyls, but high yields of protein-bound material. The peroxyl radical generator 2,2'-azobis(2-amidinopropane) hydrochloride...

  4. Measurement of oxidative damage to DNA in nanomaterial exposed cells and animals

    DEFF Research Database (Denmark)

    Møller, Peter; Jensen, Ditte Marie; Christophersen, Daniel Vest

    2015-01-01

    -reactivity with other molecules in cells. This review provides an overview of efforts to reliably detect oxidatively damaged DNA and a critical assessment of the published studies on DNA damage levels. Animal studies with high baseline levels of oxidatively damaged DNA are more likely to show positive associations...... of oxidatively damaged DNA in lung tissue. Oral exposure to nanosized carbon black, TiO2 , carbon nanotubes and ZnO is associated with elevated levels of oxidatively damaged DNA in tissues. These observations are supported by cell culture studies showing concentration-dependent associations between ENM exposure...... and oxidatively damaged DNA measured by the comet assay. Cell culture studies show relatively high variation in the ability of ENMs to oxidatively damage DNA; hence, it is currently impossible to group ENMs according to their DNA damaging potential. Environ. Mol. Mutagen., 2014. © 2014 Wiley Periodicals, Inc....

  5. Engaging unactivated alkyl, alkenyl and aryl iodides in visible-light-mediated free radical reactions

    Science.gov (United States)

    Nguyen, John D.; D'Amato, Erica M.; Narayanam, Jagan M. R.; Stephenson, Corey R. J.

    2012-10-01

    Radical reactions are a powerful class of chemical transformations. However, the formation of radical species to initiate these reactions has often required the use of stoichiometric amounts of toxic reagents, such as tributyltin hydride. Recently, the use of visible-light-mediated photoredox catalysis to generate radical species has become popular, but the scope of these radical precursors has been limited. Here, we describe the identification of reaction conditions under which photocatalysts such as fac-Ir(ppy)3 can be utilized to form radicals from unactivated alkyl, alkenyl and aryl iodides. The generated radicals undergo reduction via hydrogen atom abstraction or reductive cyclization. The reaction protocol utilizes only inexpensive reagents, occurs under mild reaction conditions, and shows exceptional functional group tolerance. Reaction efficiency is maintained upon scale-up and decreased catalyst loading, and the reaction time can be significantly shortened when the reaction is performed in a flow reactor.

  6. An anthocyanin-rich strawberry extract protects against oxidative stress damage and improves mitochondrial functionality in human dermal fibroblasts exposed to an oxidizing agent.

    Science.gov (United States)

    Giampieri, Francesca; Alvarez-Suarez, José M; Mazzoni, Luca; Forbes-Hernandez, Tamara Y; Gasparrini, Massimiliano; Gonzàlez-Paramàs, Ana M; Santos-Buelga, Celestino; Quiles, Josè L; Bompadre, Stefano; Mezzetti, Bruno; Battino, Maurizio

    2014-08-01

    This study investigates the protective effect of the Sveva strawberry polyphenol-rich extract on human dermal fibroblasts against AAPH-induced oxidative stress. The HPLC-DAD/ESI-MS analysis was used for evaluating the phenolic composition of the fruits. Sveva strawberry presented a high anthocyanin content (639.79 mg per kg fresh fruit), representing ∼86.08% of the total phenolic content, with Pg-3-glc as the most abundant representative (611.18 mg per kg fresh fruit). Only one ellagitannin (agrimoniin) was identified, while two quercetins, three kaempherol derivates, and three ellagic acid derivatives were detected and quantified. Strawberry pre-treatment (0.5 mg ml(-1)) markedly increased human dermal fibroblast viability, with a significant reduction of apoptotic and dead cells, and suppressed AAPH-induced ROS generation, after only 30 minutes of incubation with the oxidizing agent, and lipid peroxidation, against a range of AAPH concentrations tested. Notably, the strawberry extract also improved the mitochondrial functionality: the basal respiratory performance after treatment was ∼1.59-fold higher compared to control cells, while pre-treatment with strawberry extract before oxidative damage increased ∼2.70-fold compared to stressed cells. Our results confirm that the strawberry possesses antioxidant properties, and may be useful for the prevention of free radical-induced skin damage.

  7. Ursolic acid attenuates oxidative stress-mediated hepatocellular carcinoma induction by diethylnitrosamine in male Wistar rats.

    Science.gov (United States)

    Gayathri, Renganathan; Priya, D Kalpana Deepa; Gunassekaran, G R; Sakthisekaran, Dhanapal

    2009-01-01

    Hepatocellular carcinoma is the most common primary cancer of the liver in Asian countries. For more than a decade natural dietary agents including fruits, vegetables and spices have drawn a great deal of attention in the prevention of diseases, preferably cancer. Ursolic acid is a natural triterpenoid widely found in food, medicinal herbs, apple peel and other products it has been extensively studied for its anticancer and antioxidant properties. The purpose of this study was to evaluate the effect of ursolic acid in diethylnitrosamine (DEN) induced and phenobarbital promoted hepatocarcinogenesis in male Wistar rats. Antioxidant status was assessed by alterations in level of lipid peroxides and protein carbonyls. Damage to plasma membranes was assessed by levels of membrane and tissue ATPases. Liver tissue was homogenized and utilized for estimation of lipid peroxides, protein carbonyls and glycoproteins. Anticoagulated blood was utilized for erythrocyte membrane isolation. Oral administration of UA 20 mg/kg bodyweight for 6 weeks decreased the levels of lipid peroxides and protein carbonyls at a significance of pmembrane and tissue ATPases returned to normal after UA administration. Levels of glycoproteins were also restored after treatment. Histopathological observations were recorded. The findings from the above study suggest the effectiveness of UA in reducing the oxidative stress mediated changes in liver of rats. Since UA has been found to be a potent antioxidant, it can be suggested as an excellent chemopreventive agent in overcoming diseases like cancer which are mediated by free radicals.

  8. The mechanism of mediated oxidation of carboxylates with ferrocene as redox catalyst in absence of grafting effects. An experimental and theoretical approach

    International Nuclear Information System (INIS)

    Hernández-Muñoz, Lindsay S.; Galano, Annia; Astudillo-Sánchez, Pablo D.; Abu-Omar, Mahdi M.; González, Felipe J.

    2014-01-01

    Graphical abstract: - Highlights: • The mechanism of mediated oxidation of carboxylates. • Thermodynamics of the mediated Kolbe and Non-Kolbe mechanisms. • The oxidation of acetate and diphenylacetate ions by using ferrocene as redox catalyst. • Simulation and DFT calculations of the mediated oxidation of carboxylates. • Radical and carbocationic pathways in the carboxylate oxidation in acetonitrile. - Abstract: The oxidation of tetrabutylammonium carboxylates by using ferrocene derivatives as redox mediators has been recently used to perform the covalent grafting of carbon surfaces with organic and organometallic groups. Due to the intervention of this surface process, a partial description of the reaction mechanism has only been stated. Therefore, this article concerns about two features of the oxidation of carboxylates mediated by ferrocene. In the first part, it is discussed that in the oxidation of acetate ions by using ferrocene as redox catalyst, the gap between both oxidation potentials is very high, which means that the homogeneous electron transfer between the acetate ion and the electrochemically generated ferrocenium ion is energetically unfavorable. However, by using density functional theory calculations, it has been shown that the whole set of coupled chemical reactions involved either in a Kolbe or Non-Kolbe pathway drive the overall mechanisms towards a thermodynamically favorable situation. In order to avoid the strong covalent grafting process that occurs during the mediated oxidation of acetate ions, the second part of this work deals with the oxidation of tetrabutylammonium diphenylacetate by using ferrocene as a redox mediator in acetonitrile on glassy carbon electrodes. With this carboxylate, no electrode inhibition process occurs and, therefore cyclic voltammetry simulation was done to propose the electrochemical and chemical steps that are present when a carboxylate oxidation is performed in the presence of ferrocene derivatives

  9. In Situ Investigation of Electrochemically Mediated Surface-Initiated Atom Transfer Radical Polymerization by Electrochemical Surface Plasmon Resonance.

    Science.gov (United States)

    Chen, Daqun; Hu, Weihua

    2017-04-18

    Electrochemically mediated atom transfer radical polymerization (eATRP) initiates/controls the controlled/living ATRP chain propagation process by electrochemically generating (regenerating) the activator (lower-oxidation-state metal complex) from deactivator (higher-oxidation-state metal complex). Despite successful demonstrations in both of the homogeneous polymerization and heterogeneous systems (namely, surface-initiated ATRP, SI-ATRP), the eATRP process itself has never been in situ investigated, and important information regarding this process remains unrevealed. In this work, we report the first investigation of the electrochemically mediated SI-ATRP (eSI-ATRP) by rationally combining the electrochemical technique with real-time surface plasmon resonance (SPR). In the experiment, the potential of a SPR gold chip modified by the self-assembled monolayer of the ATRP initiator was controlled to electrochemically reduce the deactivator to activator to initiate the SI-ATRP, and the whole process was simultaneously monitored by SPR with a high time resolution of 0.1 s. It is found that it is feasible to electrochemically trigger/control the SI-ATRP and the polymerization rate is correlated to the potential applied to the gold chip. This work reveals important kinetic information for eSI-ATRP and offers a powerful platform for in situ investigation of such complicated processes.

  10. [The significance of free radicals and antioxidants due to the load induced by sport activity].

    Science.gov (United States)

    Holecek, V; Liska, J; Racek, J; Rokyta, R

    2004-01-01

    Sport performance is followed by a high production of free radicals. The main reasons are reperfusion after the previous imbalance between the increased need of the organism and the ability of blood supply by oxygen, increased production of ATP, decomposition of the cells particularly white blood cells, oxidation of the purin basis from DNA, stress, output of epinephrine release of free iron, increased temperature in the muscle and its inflammation, and the reception of free radicals from external environment. Peroxidation of lipids, proteins, DNA and other compounds follows the previous biochemical steps. Antioxidants are consumed by free radicals, antioxidative enzymes are released into blood plasma, intracellular calcium is increased, the production of nitric oxide rises, the levels of hydrogen peroxide and hypochlorous acid increase. These penetrate through the membranes and oxidatively damage the tissues. Training improves the ability of the organism to balance the increased load of free radicals. The damage can be lowered by the application of a mixture of antioxidants, the most important are vitamin C, A, E, glutathione, selenium, carnosine, eventually bioflavonoids and ginkgo biloba. The lack of antioxidants can significantly diminish the sport performance and therefore the supplementation with antioxidants is for top sportsmen but also for aged people advisable.

  11. Redox-Mediated and Ionizing-Radiation-Induced Inflammatory Mediators in Prostate Cancer Development and Treatment

    Science.gov (United States)

    Miao, Lu; Holley, Aaron K.; Zhao, Yanming; St. Clair, William H.

    2014-01-01

    Abstract Significance: Radiation therapy is widely used for treatment of prostate cancer. Radiation can directly damage biologically important molecules; however, most effects of radiation-mediated cell killing are derived from the generated free radicals that alter cellular redox status. Multiple proinflammatory mediators can also influence redox status in irradiated cells and the surrounding microenvironment, thereby affecting prostate cancer progression and radiotherapy efficiency. Recent Advances: Ionizing radiation (IR)–generated oxidative stress can regulate and be regulated by the production of proinflammatory mediators. Depending on the type and stage of the prostate cancer cells, these proinflammatory mediators may lead to different biological consequences ranging from cell death to development of radioresistance. Critical Issues: Tumors are heterogeneous and dynamic communication occurs between stromal and prostate cancer cells, and complicated redox-regulated mechanisms exist in the tumor microenvironment. Thus, antioxidant and anti-inflammatory strategies should be carefully evaluated for each patient at different stages of the disease to maximize therapeutic benefits while minimizing unintended side effects. Future Directions: Compared with normal cells, tumor cells are usually under higher oxidative stress and secrete more proinflammatory mediators. Thus, redox status is often less adaptive in tumor cells than in their normal counterparts. This difference can be exploited in a search for new cancer therapeutics and treatment regimes that selectively activate cell death pathways in tumor cells with minimal unintended consequences in terms of chemo- and radio-resistance in tumor cells and toxicity in normal tissues. Antioxid. Redox Signal. 20, 1481–1500. PMID:24093432

  12. Polyacrylamide grafting of modified graphene oxides by in situ free radical polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Mingyi [Department of Applied Chemistry, School of Science, Tianjin University of Commerce, Tianjin 300134 (China); Xu, Xiaoyang, E-mail: xiaoyangxu2012@163.com [School of Science, Tianjin University, Tianjin 30072 (China); Wu, Tao [School of Science, Tianjin University, Tianjin 30072 (China); Zhang, Sai; Li, Xianxian [Department of Applied Chemistry, School of Science, Tianjin University of Commerce, Tianjin 300134 (China); Li, Yi, E-mail: liyi@tju.edu.cn [School of Science, Tianjin University, Tianjin 30072 (China)

    2014-12-15

    Highlights: • Graphene oxide (GO) was modified by chemical reactions to functionalized GO (FGO). • The FGOs and the GO were then subjected to in situ free radical polymerization. • Hydroxyl groups of GO were the most reactive grafting sites. - Abstract: Graphene oxide (GO) was modified using chemical reactions to obtain three types of functionalized GO sheets (FGO). The FGO sheets and the GO were then subjected to in situ free radical polymerization in order to study the grafting polymerization. The FGO and grafted-.FGO were analyzed with Fourier transform infrared spectroscopy, scanning electronic microscopy, thermo-gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The grafting percentages in the materials were calculated using the TGA and XPS results. The FGO sheets with different functional groups exhibited different grafting abilities, and hydroxyl groups were proven to be the most reactive grafting sites for the in situ free radical grafting polymerization of polyacrylamide.

  13. Polyacrylamide grafting of modified graphene oxides by in situ free radical polymerization

    International Nuclear Information System (INIS)

    Tang, Mingyi; Xu, Xiaoyang; Wu, Tao; Zhang, Sai; Li, Xianxian; Li, Yi

    2014-01-01

    Highlights: • Graphene oxide (GO) was modified by chemical reactions to functionalized GO (FGO). • The FGOs and the GO were then subjected to in situ free radical polymerization. • Hydroxyl groups of GO were the most reactive grafting sites. - Abstract: Graphene oxide (GO) was modified using chemical reactions to obtain three types of functionalized GO sheets (FGO). The FGO sheets and the GO were then subjected to in situ free radical polymerization in order to study the grafting polymerization. The FGO and grafted-.FGO were analyzed with Fourier transform infrared spectroscopy, scanning electronic microscopy, thermo-gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The grafting percentages in the materials were calculated using the TGA and XPS results. The FGO sheets with different functional groups exhibited different grafting abilities, and hydroxyl groups were proven to be the most reactive grafting sites for the in situ free radical grafting polymerization of polyacrylamide

  14. Anti-oxidation and scavenging effects of some extracts from Chinese medicines on free radicals

    International Nuclear Information System (INIS)

    Wang Chongdao; Qiang Yizhong; Lao Qinhua; Cui Fengmei; Shao Yuan; Sun Cunpu

    1999-11-01

    The inhibiting effects of Chinonin, Quercetin and Tannic Acid on the lipid oxidation induced by radiation exposure were investigated by means of a modified TBA spectrophotometry. The scavenging effects on free radicals caused by γ-irradiation exposure of the three active principles were observed by technique of ESR. The results showed that anti-oxidation effects of Chinonin and Quercetin were better than that of Tannic Acid, while the scavenging effects of the three active principles on free radicals were similar

  15. Prevention of iron- and copper-mediated DNA damage by catecholamine and amino acid neurotransmitters, L-DOPA, and curcumin: metal binding as a general antioxidant mechanism.

    Science.gov (United States)

    García, Carla R; Angelé-Martínez, Carlos; Wilkes, Jenna A; Wang, Hsiao C; Battin, Erin E; Brumaghim, Julia L

    2012-06-07

    Concentrations of labile iron and copper are elevated in patients with neurological disorders, causing interest in metal-neurotransmitter interactions. Catecholamine (dopamine, epinephrine, and norepinephrine) and amino acid (glycine, glutamate, and 4-aminobutyrate) neurotransmitters are antioxidants also known to bind metal ions. To investigate the role of metal binding as an antioxidant mechanism for these neurotransmitters, L-dihydroxyphenylalanine (L-DOPA), and curcumin, their abilities to prevent iron- and copper-mediated DNA damage were quantified, cyclic voltammetry was used to determine the relationship between their redox potentials and DNA damage prevention, and UV-vis studies were conducted to determine iron and copper binding as well as iron oxidation rates. In contrast to amino acid neurotransmitters, catecholamine neurotransmitters, L-DOPA, and curcumin prevent significant iron-mediated DNA damage (IC(50) values of 3.2 to 18 μM) and are electrochemically active. However, glycine and glutamate are more effective at preventing copper-mediated DNA damage (IC(50) values of 35 and 12.9 μM, respectively) than L-DOPA, the only catecholamine to prevent this damage (IC(50) = 73 μM). This metal-mediated DNA damage prevention is directly related to the metal-binding behaviour of these compounds. When bound to iron or copper, the catecholamines, amino acids, and curcumin significantly shift iron oxidation potentials and stabilize Fe(3+) over Fe(2+) and Cu(2+) over Cu(+), a factor that may prevent metal redox cycling in vivo. These results highlight the disparate antioxidant activities of neurotransmitters, drugs, and supplements and highlight the importance of considering metal binding when identifying antioxidants to treat and prevent neurodegenerative disorders.

  16. The correlation between total antioxidant capacity and nitric oxide ...

    African Journals Online (AJOL)

    DNA damage was measured by comet assay and nitric oxide concentration was evaluated by Griess assay. TAC was measured in seminal plasma based on the generation of peroxyl radicals from 2,2-azinobis (2-amidino propane) dihydrochlorid (AAPH). Our results show that the means of DNA damage and nitric oxide ...

  17. Experimental studies on anti-oxidants reducing lipid peroxidation of irradiated mice

    International Nuclear Information System (INIS)

    Du Zeji; Liu Keliang; Su Liaoyuan

    1993-08-01

    The free radical plays an important role in the irradiation damage. The irradiation damage would be reduced if anti-oxidants is used, because anti-oxidants can scavenge free radicals and suppress lipid peroxidation. In the study, a fluoro-spectrophotometer was used to determine the changes of MDA levels in mice tissues and serum after irradiation and the protective effect of anti-oxidants of Vit E and DMSO on damage caused by free radicals. The results are as follows: (1) The highest MDA level was at 12 to 24 hours after irradiation dose of 3.0 Gy. (2) The MDA level is increasing with the increasing of irradiation dose. It means the MDA level can indicate the extent of irradiation damage. (3) Both Vit E and DMSO had a powerful effect on reducing MDA level, but the effect of DMSO was stronger than Vit E. The optimum doses of them were 0.25 mg/g body weight and 10 mg/g body weight respectively. (4) The best effect obtained was to use Vit E and DMSO simultaneously

  18. Copper-mediated homogeneous living radical polymerization of acrylamide with waxy potato starch-based macroinitiator.

    Science.gov (United States)

    Fan, Yifei; Cao, Huatang; van Mastrigt, Frank; Pei, Yutao; Picchioni, Francesco

    2018-07-15

    Cu 0 -mediated living radical polymerization (Cu 0 -mediated LRP) was employed in this research for the synthesis of starch-g-polyacrylamide (St-g-PAM). The use of a controlled radical grafting technique is necessary, as compared to the traditional free-radical polymerization methods, in order to obtain a well-defined structure of the final product. This is in turn essential for studying the relationship between such structure and the end-properties. Waxy potato starch-based water-soluble macroinitiator was first synthesized by esterification with 2-bromopropionyl bromide in the mixture of dimethylacetamide and lithium chloride. With the obtained macroinitiator, St-g-PAM was homogeneously synthesized by aqueous Cu 0 -mediated LRP using CuBr/hexamethylated tris(2-aminoethyl)amine (Me 6 Tren) as catalyst. The successful synthesis of the macroinitiator and St-g-PAM was proved by NMR, FT-IR, SEM, XRD and TGA analysis. The molecular weight and polydispersity of PAM chains were analyzed by gel permeation chromatography (GPC) after hydrolyzing the starch backbone. Monomer conversion was monitored by gas chromatography (GC), on the basis of which the kinetics were determined. A preliminarily rheological study was performed on aqueous solutions of the prepared materials. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. From Oxidative Stress Damage to Pathways, Networks, and Autophagy via MicroRNAs

    Directory of Open Access Journals (Sweden)

    Nikolai Engedal

    2018-01-01

    Full Text Available Oxidative stress can alter the expression level of many microRNAs (miRNAs, but how these changes are integrated and related to oxidative stress responses is poorly understood. In this article, we addressed this question by using in silico tools. We reviewed the literature for miRNAs whose expression is altered upon oxidative stress damage and used them in combination with various databases and software to predict common gene targets of oxidative stress-modulated miRNAs and affected pathways. Furthermore, we identified miRNAs that simultaneously target the predicted oxidative stress-modulated miRNA gene targets. This generated a list of novel candidate miRNAs potentially involved in oxidative stress responses. By literature search and grouping of pathways and cellular responses, we could classify these candidate miRNAs and their targets into a larger scheme related to oxidative stress responses. To further exemplify the potential of our approach in free radical research, we used our explorative tools in combination with ingenuity pathway analysis to successfully identify new candidate miRNAs involved in the ubiquitination process, a master regulator of cellular responses to oxidative stress and proteostasis. Lastly, we demonstrate that our approach may also be useful to identify novel candidate connections between oxidative stress-related miRNAs and autophagy. In summary, our results indicate novel and important aspects with regard to the integrated biological roles of oxidative stress-modulated miRNAs and demonstrate how this type of in silico approach can be useful as a starting point to generate hypotheses and guide further research on the interrelation between miRNA-based gene regulation, oxidative stress signaling pathways, and autophagy.

  20. Radiation-induced damage in T4 bacteriophage: the effect of superoxid radicals and molecular oxygen. Progress report, December 1, 1977--November 30, 1978

    International Nuclear Information System (INIS)

    Samuni, A.; Chevion, M.; Halpern, Y.S.; Ilan, Y.A.; Czapski, G.

    1978-01-01

    The sensitivity of T4 bacteriophage towards γ irradiation has been studied in phosphate buffer suspensions. The spectrum of the water radicals was controlled by a careful choice of the appropriate saturating gas and the addition of radical scavengers. Thus, it was possible to distinguish between the effects of molecular oxygen and the superoxide radicals formed through its reactions. About 90 percent of the damage was caused by the water radicals formed in the bulk suspensions. These probably affected the phage proteins; only the remainder of the damage involved the viral DNA. The oxygen enhancement ratio observed was not connected in any way with the formation of the superoxide radicals. The results confirmed that the OH radicals are the reactive species, while e - /sub aq/ as well as the superoxide radical do not contribute to the radiodamage

  1. Pulmonary Oxidative Stress, Inflammation and Cancer: Respirable Particulate Matter, Fibrous Dusts and Ozone as Major Causes of Lung Carcinogenesis through Reactive Oxygen Species Mechanisms

    Directory of Open Access Journals (Sweden)

    Spyridon Loridas

    2013-08-01

    Full Text Available Reactive oxygen or nitrogen species (ROS, RNS and oxidative stress in the respiratory system increase the production of mediators of pulmonary inflammation and initiate or promote mechanisms of carcinogenesis. The lungs are exposed daily to oxidants generated either endogenously or exogenously (air pollutants, cigarette smoke, etc.. Cells in aerobic organisms are protected against oxidative damage by enzymatic and non-enzymatic antioxidant systems. Recent epidemiologic investigations have shown associations between increased incidence of respiratory diseases and lung cancer from exposure to low levels of various forms of respirable fibers and particulate matter (PM, at occupational or urban air polluting environments. Lung cancer increases substantially for tobacco smokers due to the synergistic effects in the generation of ROS, leading to oxidative stress and inflammation with high DNA damage potential. Physical and chemical characteristics of particles (size, transition metal content, speciation, stable free radicals, etc. play an important role in oxidative stress. In turn, oxidative stress initiates the synthesis of mediators of pulmonary inflammation in lung epithelial cells and initiation of carcinogenic mechanisms. Inhalable quartz, metal powders, mineral asbestos fibers, ozone, soot from gasoline and diesel engines, tobacco smoke and PM from ambient air pollution (PM10 and PM2.5 are involved in various oxidative stress mechanisms. Pulmonary cancer initiation and promotion has been linked to a series of biochemical pathways of oxidative stress, DNA oxidative damage, macrophage stimulation, telomere shortening, modulation of gene expression and activation of transcription factors with important role in carcinogenesis. In this review we are presenting the role of ROS and oxidative stress in the production of mediators of pulmonary inflammation and mechanisms of carcinogenesis.

  2. Artifacts Generated During Azoalkane Peroxy Radical Oxidative Stress Testing of Pharmaceuticals Containing Primary and Secondary Amines.

    Science.gov (United States)

    Nefliu, Marcela; Zelesky, Todd; Jansen, Patrick; Sluggett, Gregory W; Foti, Christopher; Baertschi, Steven W; Harmon, Paul A

    2015-12-01

    We report artifactual degradation of pharmaceutical compounds containing primary and secondary amines during peroxy radical-mediated oxidative stress carried out using azoalkane initiators. Two degradation products were detected when model drug compounds dissolved in methanol/water were heated to 40°C with radical initiators such as 2,2'-azobis(2-methylpropionitrile) (AIBN). The primary artifact was identified as an α-aminonitrile generated from the reaction of the amine group of the model drug with formaldehyde and hydrogen cyanide, generated as byproducts of the stress reaction. A minor artifact was generated from the reaction between the amine group and isocyanic acid, also a byproduct of the stress reaction. We report the effects of pH, initiator/drug molar ratio, and type of azoalkane initiator on the formation of these artifacts. Mass spectrometry and nuclear magnetic resonance were used for structure elucidation, whereas mechanistic studies, including stable isotope labeling experiments, cyanide analysis, and experiments exploring the effects of butylated hydroxyanisole addition, were employed to support the degradation pathways. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  3. Radicals of DNA and DNA nucleotides generated by ionising radiation

    International Nuclear Information System (INIS)

    Przybytniak, G.

    2004-01-01

    A first stage of cell processes leading to DNA damage of initiated by radical reactions. In a model system such transformations were generated by ionising radiation which involves production of electron loss and electron gain centers of the substrate and radical formation. Using cryogenic ESR spectroscopy it was found that the DNA nucleotides, which convert to radical anions upon electron capture undergo the separation of unpaired spin and charge due to protonation. Circular and linear dichroism studies enabled to conclude that iron ions(III) induce strong changes in the DNA helical structure indicating their coordination with nitrogen bases. The repair of DNA radicals produced via radiolytic oxidation, i.e. the guanine radical cation and the allyl type radical of thymine, is possible at elevated temperatures due to the involvement of sulphydryl groups. The influence of the thiol charge is then limited

  4. Mechanisms leading to oligomers and SOA through aqueous photooxidation: insights from OH radical oxidation of acetic acid and methylglyoxal

    Directory of Open Access Journals (Sweden)

    Y. Tan

    2012-01-01

    Full Text Available Previous experiments have demonstrated that the aqueous OH radical oxidation of methylglyoxal produces low volatility products including pyruvate, oxalate and oligomers. These products are found predominantly in the particle phase in the atmosphere, suggesting that methylglyoxal is a precursor of secondary organic aerosol (SOA. Acetic acid plays a central role in the aqueous oxidation of methylglyoxal and it is a ubiquitous product of gas phase photochemistry, making it a potential "aqueous" SOA precursor in its own right. However, the fate of acetic acid upon aqueous-phase oxidation is not well understood. In this research, acetic acid (20 μM–10 mM was oxidized by OH radicals, and pyruvic acid and methylglyoxal experimental samples were analyzed using new analytical methods, in order to better understand the formation of SOA from acetic acid and methylglyoxal. Glyoxylic, glycolic, and oxalic acids formed from acetic acid and OH radicals. In contrast to the aqueous OH radical oxidation of methylglyoxal, the aqueous OH radical oxidation of acetic acid did not produce succinic acid and oligomers. This suggests that the methylgloxal-derived oligomers do not form through the acid catalyzed esterification pathway proposed previously. Using results from these experiments, radical mechanisms responsible for oligomer formation from methylglyoxal oxidation in clouds and wet aerosols are proposed. The importance of acetic acid/acetate as an SOA precursor is also discussed. We hypothesize that this and similar chemistry is central to the daytime formation of oligomers in wet aerosols.

  5. Watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai) juice modulates oxidative damage induced by low dose X-ray in mice.

    Science.gov (United States)

    Mohammad, Mohd Khairul Amran; Mohamed, Muhamad Idham; Zakaria, Ainul Mardhiyah; Abdul Razak, Hairil Rashmizal; Saad, Wan Mazlina Md

    2014-01-01

    Watermelon is a natural product that contains high level of antioxidants and may prevent oxidative damage in tissues due to free radical generation following an exposure to ionizing radiation. The present study aimed to investigate the radioprotective effects of watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai) juice against oxidative damage induced by low dose X-ray exposure in mice. Twelve adult male ICR mice were randomly divided into two groups consisting of radiation (Rx) and supplementation (Tx) groups. Rx received filtered tap water, while Tx was supplemented with 50% (v/v) watermelon juice for 28 days ad libitum prior to total body irradiation by 100 μGy X-ray on day 29. Brain, lung, and liver tissues were assessed for the levels of malondialdehyde (MDA), apurinic/apyrimidinic (AP) sites, glutathione (GSH), and superoxide dismutase (SOD) inhibition activities. Results showed significant reduction of MDA levels and AP sites formation of Tx compared to Rx (P watermelon juice restore the intracellular antioxidant activities by significantly increased SOD inhibition activities and GSH levels compared to Rx. These findings may postulate that supplementation of 50% watermelon (Citrullus lanatus (Thunb.) Matsum. and Nakai) juice could modulate oxidative damage induced by low dose X-ray exposure.

  6. Preterm newborns show slower repair of oxidative damage and paternal smoking associated DNA damage.

    Science.gov (United States)

    Vande Loock, Kim; Ciardelli, Roberta; Decordier, Ilse; Plas, Gina; Haumont, Dominique; Kirsch-Volders, Micheline

    2012-09-01

    Newborns have to cope with hypoxia during delivery and a sudden increase in oxygen at birth. Oxygen will partly be released as reactive oxygen species having the potential to cause damage to DNA and proteins. In utero, increase of most (non)-enzymatic antioxidants occurs during last weeks of gestation, making preterm neonates probably more sensitive to oxidative stress. Moreover, it has been hypothesized that oxidative stress might be the common etiological factor for certain neonatal diseases in preterm infants. The aim of this study was to assess background DNA damage; in vitro H(2)O(2) induced oxidative DNA damage and repair capacity (residual DNA damage) in peripheral blood mononucleated cells from 25 preterm newborns and their mothers. In addition, demographic data were taken into account and repair capacity of preterm was compared with full-term newborns. Multivariate linear regression analysis revealed that preterm infants from smoking fathers have higher background DNA damage levels than those from non-smoking fathers, emphasizing the risk of paternal smoking behaviour for the progeny. Significantly higher residual DNA damage found after 15-min repair in preterm children compared to their mothers and higher residual DNA damage after 2 h compared to full-term newborns suggest a slower DNA repair capacity in preterm children. In comparison with preterm infants born by caesarean delivery, preterm infants born by vaginal delivery do repair more slowly the in vitro induced oxidative DNA damage. Final impact of passive smoking and of the slower DNA repair activity of preterm infants need to be confirmed in a larger study population combining transgenerational genetic and/or epigenetic effects, antioxidant levels, genotypes, repair enzyme efficiency/levels and infant morbidity.

  7. Characterization of protein interactomes of DNA damages: application to oxidation injuries

    International Nuclear Information System (INIS)

    Pietras-Barbier, Ewa

    2013-01-01

    Cyclo-nucleosides are complex DNA damages implying both bases and sugar residues. They are generated by free radicals, in particular by the effect of ionizing radiations, and are not easily covered by cellular mechanisms. Using a protein trapping technique on probes containing these injuries, the negative influence of cyclo-nucleosides on the recognition of its target sequence by a DREF transcription factor and on the interactions of PARP1 with DNA have been identified. Interactions between Fpg bacterial glycosylase and cyclo-nucleosides have been analysed and it has been found that this enzyme has an affinity for them, without excision activity. Finally, a Thermococcus gammatolerans radiation resistant archae has been studied: the formation of simple and complex oxidation injuries at strong radiation doses has been measured and the action mechanism of two new glycosylases has been explained. (author) [fr

  8. beta-Scission of C-3 (beta-carbon) alkoxyl radicals on peptides and proteins

    DEFF Research Database (Denmark)

    Headlam, H A; Mortimer, A; Easton, C J

    2000-01-01

    Exposure of proteins to radicals in the presence of O(2) brings about multiple changes in the target molecules. These alterations include oxidation of side chains, fragmentation, cross-linking, changes in hydrophobicity and conformation, altered susceptibility to proteolytic enzymes, and formation...... of methanal (formaldehyde). This product has been quantified with a number of oxidized peptides and proteins, and can account for up to 64% of the initial attacking radicals with some Ala peptides. When quantified together with the hydroperoxide precursors, these species account for up to 80% of the initial...... radicals, confirming that this is a major process. Methanal causes cell toxicity and DNA damage and is an animal carcinogen and a genotoxic agent in human cells. Thus, the formation and subsequent reaction of alkoxyl radicals formed at the C-3 position on aliphatic amino acid side chains on peptides...

  9. Radical scavenging potential and DNA damage protection of wild edible mushrooms of Kashmir Himalaya

    Directory of Open Access Journals (Sweden)

    Nowsheen Shameem

    2017-10-01

    Full Text Available The edible mushrooms Verpa bohemica and Morchella esculenta are locally used for dietary and antioxidant in tribal areas of Kashmir Himalaya. In the present study, sequences of solvents on the basis of their polarity were used for the extraction from selected mushrooms. The comprehensive antioxidant activity of all edible mushroom extracts was evaluated by seven different methods. V. bohemica exhibited significant inhibitory activity of radicals among all the mushrooms while Morchella extracts protected the DNA damage from OH· radicals. This study provides us the substantiation for the use of these mushrooms as antioxidants besides being already eaten as food.

  10. Study of anti-oxidation and scavenging effects on free radicals of quercetin

    International Nuclear Information System (INIS)

    Wang Chongdao; Qiang Yizhong; Lao Qinhua; Shao Yuan

    1999-01-01

    The effects of Quercetin on the contents of lipid peroxides (LPO) in the mice caused by γ-whole-body irradiation by method of the modified spectrophotometry of TBA, and the scavenging effects of Quercetin on the free radicals of DNA induced by radiation exposure by means of ESR technique were investigated. The results demonstrates that Quercetin has a good anti-oxidation effect and is very effective in scavenging of free radicals

  11. Inflammation, oxidative DNA damage, and carcinogenesis

    International Nuclear Information System (INIS)

    Lewis, J.G.; Adams, D.O.

    1987-01-01

    Inflammation has long been associated with carcinogenesis, especially in the promotion phase. The mechanism of action of the potent inflammatory agent and skin promoter 12-tetradecanoyl phorbol-13-acetate (TPA) is unknown. It is though that TPA selectively enhances the growth of initiated cells, and during this process, initiated cells progress to the preneoplastic state and eventually to the malignant phenotype. The authors and others have proposed that TPA may work, in part, by inciting inflammation and stimulating inflammatory cells to release powerful oxidants which then induce DNA damage in epidermal cells. Macrophages cocultured with target cells and TPA induce oxidized thymine bases in the target cells. This process is inhibited by both catalase and inhibitors of lipoxygenases, suggesting the involvement of both H 2 O 2 and oxidized lipid products. In vivo studies demonstrated that SENCAR mice, which are sensitive to promotion by TPA, have a more intense inflammatory reaction in skin that C57LB/6 mice, which are resistant to promotion by TPA. In addition, macrophages from SENCAR mice release more H 2 O 2 and metabolites of AA, and induce more oxidative DNA damage in cocultured cells than macrophages from C57LB/6 mice. These data support the hypothesis that inflammation and the release of genotoxic oxidants may be one mechanism whereby initiated cells receive further genetic insults. They also further complicate risk assessment by suggesting that some environmental agents may work indirectly by subverting host systems to induce damage rather than maintaining homeostasis

  12. Environmental factors and unhealthy lifestyle influence oxidative stress in humans--an overview.

    Science.gov (United States)

    Aseervatham, G Smilin Bell; Sivasudha, T; Jeyadevi, R; Arul Ananth, D

    2013-07-01

    Oxygen is the most essential molecule for life; since it is a strong oxidizing agent, it can aggravate the damage within the cell by a series of oxidative events including the generation of free radicals. Antioxidative agents are the only defense mechanism to neutralize these free radicals. Free radicals are not only generated internally in our body system but also trough external sources like environmental pollution, toxic metals, cigarette smoke, pesticides, etc., which add damage to our body system. Inhaling these toxic chemicals in the environment has become unavoidable in modern civilization. Antioxidants of plant origin with free radical scavenging properties could have great importance as therapeutic agents in several diseases caused by environmental pollution. This review summarizes the generation of reactive oxygen species and damage to cells by exposure to external factors, unhealthy lifestyle, and role of herbal plants in scavenging these reactive oxygen species.

  13. Increased oxidative stress mediates the antitumor effect of PARP inhibition in ovarian cancer

    Directory of Open Access Journals (Sweden)

    Dong Hou

    2018-07-01

    Full Text Available PARP inhibitors have been widely tested in clinical trials, especially for the treatment of breast cancer and ovarian cancer, and were shown to be highly successful. Because PARP primarily functions in sensing and repairing DNA strand breaks, the therapeutic effect of PARP inhibition is generally believed to be attributed to impaired DNA repair. We here report that oxidative stress is also increased by PARP inhibition and mediates the antitumor effect. We showed that PARP1 is highly expressed in specimens of high grade serous ovarian carcinoma and its activity is required for unperturbed proliferation of ovarian cancer cells. Inhibition or depletion of PARP leads to not only an increase in DNA damage, but also an elevation in the levels of reactive oxygen species (ROS. Importantly, antioxidant N-acetylcysteine (NAC significantly attenuated the induction of DNA damage and the perturbation of proliferation by PARP inhibition or depletion. We further showed that NADPH oxidases 1 and 4 were significantly upregulated by PARP inhibition and were partially responsible for the induction of oxidative stress. Depletion of NOX1 and NOX4 partially rescued the growth inhibition of PARP1-deficient tumor xenografts. Our findings suggest that in addition to compromising the repair of DNA damage, PARP inhibition or depletion may exert extra antitumor effect by elevating oxidative stress in ovarian cancer cells. Keywords: PARP1, Oxidative stress, NADPH oxidases, Ovarian cancer

  14. Involvement of the nitric oxide in melatonin-mediated protection against injury.

    Science.gov (United States)

    Fan, Wenguo; He, Yifan; Guan, Xiaoyan; Gu, Wenzhen; Wu, Zhi; Zhu, Xiao; Huang, Fang; He, Hongwen

    2018-05-01

    Melatonin is a hormone mainly synthesized by the pineal gland in vertebrates and known well as an endogenous regulator of circadian and seasonal rhythms. It has been demonstrated that melatonin is involved in many physiological and pathophysiological processes showing antioxidant, anti-apoptotic and anti-inflammatory properties. Nitric oxide (NO) is a free radical gas in the biological system, which is produced by nitric oxide synthase (NOS) family. NO acts as a biological mediator and plays important roles in different systems in humans. The NO/NOS system exerts a broad spectrum of signaling functions. Accumulating evidence has clearly revealed that melatonin regulates NO/NOS system through multiple mechanisms that may influence physiological and pathophysiological processes. This article reviews the latest evidence for the effects of melatonin on NO/NOS regulation in different organs and disease conditions, the potential cellular mechanisms by which melatonin is involved in organ protection are discussed. Copyright © 2018 Elsevier Inc. All rights reserved.

  15. Radical reactions in vivo - an overview

    International Nuclear Information System (INIS)

    Saran, M.; Bors, W.

    1990-01-01

    Generation of radicals in vivo depends on metabolic activities. The reactions are usually influenced by (i) the presence and concentration of oxygen, (ii) the availability of transition metals (effects of binding and compartimentalization), (iii) the level of reductants and antioxidants (e.g. nutritional effects). The effects of radicals are thought to be due to (i) membrane damage (affecting passive or active transport through altered fluidity/function interrelationships, intercellular messenging through modifications in the synthesis of prostaglandins and leukotrienes); (ii) protein damage (e.g. affecting membrane transporters, channel proteins, receptor or regulatory proteins, immunomodulators); (iii) damage to DNA. Defense mechanisms consist of (i) prevention of the 'spreading' of primary damage by low molecular weight antioxidants (e.g. vitamin E, GSH, vitamin C, β-carotene, uric acid); (ii) prevention or limitation of 'secondary' damage by enzymes (e.g. GSH-peroxidase, catalase, superoxide dismutase, DT-diaphorase) and/or chelators; (iii) repair processes, e.g. lipid degradation/membrane repair enzymes (phospholipases, peroxidases, some transferases and reductases), protein disposal or repair enzymes (proteases, GSSG-reductase), DNA degradation or repair enzymes (exonucleases III, endonucleases III and IV, glycosylases, polymerases). Recent hypotheses on a messenging function of the superoxide anion O 2 - are discussed and possible implications of cross-reactions between O 2 - and nitric oxide (endothelium-derived relaxing factor EDRF) are shortly mentioned. (orig.)

  16. Consecutive dynamic resolutions of phosphine oxides

    NARCIS (Netherlands)

    Kortmann, Felix A.; Chang, Mu Chieh; Otten, Edwin; Couzijn, Erik P A; Lutz, Martin|info:eu-repo/dai/nl/304828971; Minnaard, Adriaan J.

    2014-01-01

    A crystallization-induced asymmetric transformation (CIAT) involving a radical-mediated racemization provides access to enantiopure secondary phosphine oxides. A consecutive CIAT is used to prepare enantio- and diastereo-pure tert-butyl(hydroxyalkyl)phenylphosphine oxides. © 2014 The Royal Society

  17. Investigating free radical generation in HepG2 cells using immuno-spin trapping.

    Science.gov (United States)

    Horinouchi, Yuya; Summers, Fiona A; Ehrenshaft, Marilyn; Kawazoe, Kazuyoshi; Tsuchiya, Koichiro; Tamaki, Toshiaki; Mason, Ronald P

    2014-10-01

    Oxidative stress can induce the generation of free radicals, which are believed to play an important role in both physiological and pathological processes and a number of diseases such as cancer. Therefore, it is important to identify chemicals which are capable of inducing oxidative stress. In this study, we evaluated the ability of four environmental chemicals, aniline, nitrosobenzene (NB), N,N-dimethylaniline (DMA) and N,N-dimethyl-4-nitrosoaniline (DMNA), to induce free radicals and cellular damage in the hepatoma cell line HepG2. Cytotoxicity was assessed using lactate dehydrogenase (LDH) assays and morphological changes were observed using phase contrast microscopy. Free radicals were detected by immuno-spin trapping (IST) in in-cell western experiments or in confocal microscopy experiments to determine the subcellular localization of free radical generation. DMNA induced free radical generation, LDH release and morphological changes in HepG2 cells whereas aniline, NB and DMA did not. Confocal microscopy showed that DMNA induced free radical generation mainly in the cytosol. Preincubation of HepG2 cells with N-acetylcysteine and 2,2'-dipyridyl significantly prevented free radical generation upon subsequent incubation with DMNA, whereas preincubation with apocynin and dimethyl sulfoxide did not. These results suggest that DMNA induces oxidative stress and that reactive oxygen species, metals and free radical generation play a critical role in DMNA-induced cytotoxicity. Copyright © 2014. Published by Elsevier Inc.

  18. Fetal programming and early identification of newborns at high risk of free radical-mediated diseases.

    Science.gov (United States)

    Perrone, Serafina; Santacroce, Antonino; Picardi, Anna; Buonocore, Giuseppe

    2016-05-08

    Nowadays metabolic syndrome represents a real outbreak affecting society. Paradoxically, pediatricians must feel involved in fighting this condition because of the latest evidences of developmental origins of adult diseases. Fetal programming occurs when the normal fetal development is disrupted by an abnormal insult applied to a critical point in intrauterine life. Placenta assumes a pivotal role in programming the fetal experience in utero due to the adaptive changes in structure and function. Pregnancy complications such as diabetes, intrauterine growth restriction, pre-eclampsia, and hypoxia are associated with placental dysfunction and programming. Many experimental studies have been conducted to explain the phenotypic consequences of fetal-placental perturbations that predispose to the genesis of metabolic syndrome, obesity, diabetes, hyperinsulinemia, hypertension, and cardiovascular disease in adulthood. In recent years, elucidating the mechanisms involved in such kind of process has become the challenge of scientific research. Oxidative stress may be the general underlying mechanism that links altered placental function to fetal programming. Maternal diabetes, prenatal hypoxic/ischaemic events, inflammatory/infective insults are specific triggers for an acute increase in free radicals generation. Early identification of fetuses and newborns at high risk of oxidative damage may be crucial to decrease infant and adult morbidity.

  19. Tissue Prx I in the protection against Fe-NTA and the reduction of nitroxyl radicals

    International Nuclear Information System (INIS)

    Uwayama, Junya; Hirayama, Aki; Yanagawa, Toru; Warabi, Eiji; Sugimoto, Rika; Itoh, Ken; Yamamoto, Masayuki; Yoshida, Hiroshi; Koyama, Akio; Ishii, Tetsuro

    2006-01-01

    Peroxiredoxin I (Prx I) is a key cytoplasmic peroxidase that reduces intracellular hydroperoxides in concert with thioredoxin. To study the role of tissue Prx I in protection from oxidative stress, we generated Prx I -/- mice by gene trapping. We then evaluated the acute-phase tissue damage caused by ferric-nitrilotriacetate (Fe-NTA). Increases in serum aspartate aminotransferase and alanine aminotransferase levels were significantly greater in Prx I -/- than wild-type mice, 4 and 12 h after the injection of Fe-NTA. Using real-time EPR imaging, we examined the reduction of the stable paramagnetic nitroxyl radical 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl in vivo, and found that the half-life of this spin probe in the liver and kidney was significantly prolonged in the Prx I -/- mice. These results demonstrate that Prx I -/- mice have less reducing activity and are more susceptible to the damage mediated by reactive oxygen species in vivo than wild-type mice

  20. Evaluation of the Antioxidant and Anti-glication Effects of the Hexane Extract from Piper auritum Leaves in Vitro and Beneficial Activity on Oxidative Stress and Advanced Glycation End-Product-Mediated Renal Injury in Streptozotocin-Treated Diabetic Rats

    Directory of Open Access Journals (Sweden)

    Adriana Maria Neira Gonzalez

    2012-10-01

    Full Text Available The aim of this study was to investigate the antioxidant activity of hexane extracts from leaves of Piper auritum (HS. Eight complementary in vitro test methods were used, including inhibition of DPPH· radicals, nitric oxide, superoxide anion, ion-chelating, ABTS, oxygen radical absorbance capacity, β-carotene bleaching and peroxy radical scavenging. The results indicated that HS possesses high antioxidant activity. To add to these finding we tested the effect against oxidative stress in liver, pancreas and kidney in diabetic rats. Low levels of SOD, CAT, GPx and GSH in diabetic rats were reverted to near normal values after treatment with HS. These results suggest that P. auritum prevents oxidative stress, acting as a suppressor of liver cell damage. Given the link between glycation and oxidation, we proposed that HS might possess significant in vitro antiglycation activity. Our data confirmed the inhibitory effect of HS on bovine serum albumin, serum glycosylated protein, glycation of LDL, and glycation hemoglobin. The effect of HS on diabetic renal damage was investigated using streptozotocin-induced diabetic rats. The oral administration of HS at a dose of 200 and 400 mg/kg body weight/day for 28 days significantly reduced advanced glycation endproduct (AGE formation, elevated renal glucose and thiobarbituric acid-reactive substance levels in the kidneys of diabetic rats. This implies that HS would alleviate the oxidative stress under diabetes through the inhibition of lipid peroxidation. These findings indicate that oxidative stress is increased in the diabetic rat kidney and that HS can prevent renal damage associated with diabetes by attenuating the oxidative stress.

  1. Iron induced RNA-oxidation in the general population and in mouse tissue

    DEFF Research Database (Denmark)

    Cejvanovic, Vanja; Kjær, Laura Kofoed; Bergholdt, Helle Kirstine Mørup

    2018-01-01

    Iron promotes formation of hydroxyl radicals by the Fenton reaction, subsequently leading to potential oxidatively generated damage of nucleic acids. Oxidatively generated damage to RNA, measured as 8-oxo-7,8-dihydroguanosine (8-oxoGuo) in urine, is increased in patients with genetic iron overloa...

  2. The Inhibitory Effects of Aqueous Extract from Guava Twigs, Psidium guajava L., on Mutation and Oxidative Damage

    Directory of Open Access Journals (Sweden)

    Zhi-Chyang Kang

    2013-01-01

    Full Text Available This study examines the inhibitory effects of the aqueous extract from guava twigs (GTE, Psidium guajava L., on mutation and oxidative damage. The results show that GTE inhibits the mutagenicity of 4-nitroquinoline-N-oxide (4-NQO, a direct mutagen, and 2-aminoanthracene (2-AA, an indirect mutagen, toward Salmonella typhimurium TA 98 and TA 100. In addition, GTE shows radical scavenging, reducing activities, tyrosinase inhibition, and liposome protection effects. Meanwhile, GTE in the range of 0.1–0.4 mg/mL protects liver cells from tert-butyl-hydroperoxide-(t-BHP- induced cytotoxicity. Furthermore, the cytotoxicity inhibition of GTE in the t-BHP-treated cells was demonstrated in a dose-dependent manner. High-performance liquid chromatography analysis suggests that the major phenolic constituents in GTE are gallic acid, ferulic acid, and myricetin. These active phenolic components may contribute to the biological protective effects of GTE in different models. The data suggest that GTE exhibiting biological activities can be applied to antimutation, antityrosinase, and antioxidative damage.

  3. Epigenetic oxidative redox shift (EORS) theory of aging unifies the free radical and insulin signaling theories.

    Science.gov (United States)

    Brewer, Gregory J

    2010-03-01

    Harman's free radical theory of aging posits that oxidized macromolecules accumulate with age to decrease function and shorten life-span. However, nutritional and genetic interventions to boost anti-oxidants have generally failed to increase life-span. Furthermore, the free radical theory fails to explain why exercise causes higher levels of oxyradical damage, but generally promotes healthy aging. The separate anti-aging paradigms of genetic or caloric reductions in the insulin signaling pathway is thought to slow the rate of living to reduce metabolism, but recent evidence from Westbrook and Bartke suggests metabolism actually increases in long-lived mice. To unify these disparate theories and data, here, we propose the epigenetic oxidative redox shift (EORS) theory of aging. According to EORS, sedentary behavior associated with age triggers an oxidized redox shift and impaired mitochondrial function. In order to maintain resting energy levels, aerobic glycolysis is upregulated by redox-sensitive transcription factors. As emphasized by DeGrey, the need to supply NAD(+) for glucose oxidation and maintain redox balance with impaired mitochondrial NADH oxidoreductase requires the upregulation of other oxidoreductases. In contrast to the 2% inefficiency of mitochondrial reduction of oxygen to the oxyradical, these other oxidoreductases enable glycolytic energy production with a deleterious 100% efficiency in generating oxyradicals. To avoid this catastrophic cycle, lactate dehydrogenase is upregulated at the expense of lactic acid acidosis. This metabolic shift is epigenetically enforced, as is insulin resistance to reduce mitochondrial turnover. The low mitochondrial capacity for efficient production of energy reinforces a downward spiral of more sedentary behavior leading to accelerated aging, increased organ failure with stress, impaired immune and vascular functions and brain aging. Several steps in the pathway are amenable to reversal for exit from the vicious

  4. Radioprotection against DNA damage by an extract of Indian green mussel, Perna viridis (L.)

    Digital Repository Service at National Institute of Oceanography (India)

    Kumaran, S.P.; Kutty, B.C.; Chatterji, A.; Parameswaran, P.S.; Mishra, K.P.

    -irradiation Prevention of DNA damage both in plasmid and lymphocytes and cell death in lymphocytes appears correlated with reduction of oxidatively generated free radicals It is concluded that protection against radiation-induced cell death and DNA damage by MH...

  5. Oxidative stress in ageing of hair.

    Science.gov (United States)

    Trüeb, Ralph M

    2009-01-01

    Experimental evidence supports the hypothesis that oxidative stress plays a major role in the ageing process. Reactive oxygen species are generated by a multitude of endogenous and environmental challenges. Reactive oxygen species or free radicals are highly reactive molecules that can directly damage cellular structural membranes, lipids, proteins, and DNA. The body possesses endogenous defence mechanisms, such as antioxidative enzymes and non-enzymatic antioxidative molecules, protecting it from free radicals by reducing and neutralizing them. With age, the production of free radicals increases, while the endogenous defence mechanisms decrease. This imbalance leads to the progressive damage of cellular structures, presumably resulting in the ageing phenotype. Ageing of hair manifests as decrease of melanocyte function or graying, and decrease in hair production or alopecia. There is circumstantial evidence that oxidative stress may be a pivotal mechanism contributing to hair graying and hair loss. New insights into the role and prevention of oxidative stress could open new strategies for intervention and reversal of the hair graying process and age-dependent alopecia.

  6. Oxidative damage to chloroplasts from Chlorella vulgaris exposed to ultraviolet-B radiation

    International Nuclear Information System (INIS)

    Malanga, G.; Calmanovici, G.; Puntarulo, S.

    1997-01-01

    Upon UV-B irradiation, Chlorella vulgaris cells and isolated chloroplasts increased in size and starch accumulation. Photosynthetic capacity and chlorophyll content of chloroplasts isolated from irradiated algae decreased by 72 and 66%, as compared to chloroplasts isolated from control cells. Dihydrorhodamine 123 conversion to rhodamine 123 was used as a sensitive method for detection of peroxide (presumably hydrogen peroxide) formation in isolated chloroplasts. The accumulation of rhodamine 123 is higher in irradiated than in nonirradiated chloroplasts and the increased accumulation of rhodamine 123 depended on the UV-B dose. Quantitation of alkyl radical-EPR signals in chloroplasts indicated that UV-B exposure significantly increased radical content in the membranes. The content of an oxidized DNA base (8-hydroxy-2′-deoxyguanosine) in chloroplasts was increased by 72 and 175% after irradiation of the algal culture with 17.3 and 42.6 kJ m −2 , respectively. The chloroplastic activity of superoxide dismutase decreased by 50% as compared with control values after irradiation with 42.6 kJ m −2 and no changes in ascorbate peroxidase activity and ascorbic acid content were detected at the irradiation doses tested. The β-carotene content in chloroplasts was not affected by the irradiation, but the α-tocopherol content increased approximately 4-fold after UV-B irradiation. The results suggest that oxidative damage related to UV-B exposure is responsible for alterations in chloroplasts function and integrity, and that an antioxidant response is triggered in chloroplasts through an increase in α-tocopherol content. (author)

  7. Oxidative damage mediated iNOS and UCP-2 upregulation in rat brain after sub-acute cyanide exposure: dose and time-dependent effects.

    Science.gov (United States)

    Bhattacharya, Rahul; Singh, Poonam; John, Jebin Jacob; Gujar, Niranjan L

    2018-04-03

    Cyanide-induced chemical hypoxia is responsible for pronounced oxidative damage in the central nervous system. The disruption of mitochondrial oxidative metabolism has been associated with upregulation of uncoupling proteins (UCPs). The present study addresses the dose- and time-dependent effect of sub-acute cyanide exposure on various non-enzymatic and enzymatic oxidative stress markers and their correlation with inducible-nitric oxide synthase (iNOS) and uncoupling protein-2 (UCP-2) expression. Animals received (oral) triple distilled water (vehicle control), 0.25 LD50 potassium cyanide (KCN) or 0.50 LD50 KCN daily for 21 d. Animals were sacrificed on 7, 14 and 21 d post-exposure to measure serum cyanide and nitrite, and brain malondialdehyde (MDA), reduced glutathione (GSH), glutathione disulfide (GSSG), cytochrome c oxidase (CCO), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR) and catalase (CA) levels, together with iNOS and UCP-2 expression, and DNA damage. The study revealed that a dose- and time-dependent increase in cyanide concentration was accompanied by corresponding CCO inhibition and elevated MDA levels. Decrease in GSH levels was not followed by reciprocal change in GSSG levels. Diminution of SOD, GPx, GR and CA activity was congruent with elevated nitrite levels and upregulation of iNOS and UCP-2 expression, without any DNA damage. It was concluded that long-term cyanide exposure caused oxidative stress, accompanied by upregulation of iNOS. The upregulation of UCP-2 further sensitized the cells to cyanide and accentuated the oxidative stress, which was independent of DNA damage.

  8. Ochratoxin A: induction of (oxidative) DNA damage, cytotoxicity and apoptosis in mammalian cell lines and primary cells

    International Nuclear Information System (INIS)

    Kamp, Hennicke G.; Eisenbrand, Gerhard; Schlatter, Josef; Wuerth, Kirsten; Janzowski, Christine

    2005-01-01

    Ochratoxin A (OTA) is a nephrotoxic/-carcinogenic mycotoxin, produced by several Aspergillus- and Penicillium-strains. Humans are exposed to OTA via food contamination, a causal relationship of OTA to human endemic Balkan nephropathy is still under debate. Since DNA-adducts of OTA or its metabolites could not be identified unambiguously, its carcinogenic effectiveness might be related to secondary effects, such as oxidative cell damage or cell proliferation. In this study, OTA mediated induction of (oxidative) DNA damage, cytotoxicity (necrosis, growth inhibition, apoptosis) and modulation of glutathione were investigated in cell lines (V79, CV-1) and primary rat kidney cells. After 24 h incubation, viability of V79 cells was strongly decreased by OTA concentrations >2.5 μmol/L, whereas CV-1 cells were clearly less sensitive. Strong growth inhibition occurred in both cell lines (IC 50 ∼2 μmol/L). Apoptosis, detected with an immunochemical test and with flow cytometry, was induced by >1 μmol/L OTA. Oxidative DNA damage, detected by comet assay after additional treatment with repair enzymes, was induced in all cell systems already at five-fold lower concentrations. Glutathione in CV-1 cells was depleted after 1 h incubation (>100 μmol/L). In contrast, an increase was measured after 24 h incubation (>0.5 μmol/L). In conclusion, OTA induces oxidative DNA damage at low, not yet cytotoxic concentrations. Oxidative DNA damage might initiate cell transformation eventually in connection with proliferative response following cytotoxic cell death. Both events might represent pivotal factors in the chain of cellular events leading into nephro-carcinogenicity of OTA

  9. Up-regulation of A1M/α1-microglobulin in skin by heme and reactive oxygen species gives protection from oxidative damage.

    Science.gov (United States)

    Olsson, Magnus G; Allhorn, Maria; Larsson, Jörgen; Cederlund, Martin; Lundqvist, Katarina; Schmidtchen, Artur; Sørensen, Ole E; Mörgelin, Matthias; Akerström, Bo

    2011-01-01

    During bleeding the skin is subjected to oxidative insults from free heme and radicals, generated from extracellular hemoglobin. The lipocalin α(1)-microglobulin (A1M) was recently shown to have reductase properties, reducing heme-proteins and other substrates, and to scavenge heme and radicals. We investigated the expression and localization of A1M in skin and the possible role of A1M in the protection of skin tissue from damage induced by heme and reactive oxygen species. Skin explants, keratinocyte cultures and purified collagen I were exposed to heme, reactive oxygen species, and/or A1M and investigated by biochemical methods and electron microscopy. The results demonstrate that A1M is localized ubiquitously in the dermal and epidermal layers, and that the A1M-gene is expressed in keratinocytes and up-regulated after exposure to heme and reactive oxygen species. A1M inhibited the heme- and reactive oxygen species-induced ultrastructural damage, up-regulation of antioxidation and cell cycle regulatory genes, and protein carbonyl formation in skin and keratinocytes. Finally, A1M bound to purified collagen I (K(d) = 0.96×10(-6) M) and could inhibit and repair the destruction of collagen fibrils by heme and reactive oxygen species. The results suggest that A1M may have a physiological role in protection of skin cells and matrix against oxidative damage following bleeding.

  10. Mechanisms of DNA damage by the tumor promoter and progressor benzoyl peroxide

    International Nuclear Information System (INIS)

    Swauger, J.E.; Dolan, P.M.; Zweier, J.L.; Kensler, T.W.

    1990-01-01

    Benzoyl peroxide (BzPO), a tumor promoter and progressor in mouse skin, produces strand breaks in DNA of exposed cells. Previously we have reported that the metabolism of BzPO in keratinocytes proceeds via the initial cleavage of the peroxide bond, yielding benzoyloxyl radicals which, in turn, can fragment to form phenyl radicals and carbon dioxide. Benzoic acid, the product of hydrogen abstraction by the benzoyloxyl radical, is the major stable metabolite of BzPO produced by keratinocytes. In the present study we have examined the capacity of BzPO to generate strand scissions in φX-174 plasmid DNA. DNA damage was dose-dependent over a concentration range of 10-1000 μM BzPO and was dependent on the presence of copper but not other transition state metals. By contrast, benzoic acid did not produce DNA damage in this system. The inclusion of spin trapping agents (PBN, DBNBS), radical scavenging agents (Nal, GSH), or the copper chelator o-phenanthroline in incubations was found to significantly reduce the extent of DNA damage. Electron paramagnetic resonance spectroscopy studies suggested that the primary radical trapped was the benzoyloxyl radical, implying a role for this radical in the generation of the observed DNA damage. Collectively these observations suggest BzPO may be activated to DNA damaging intermediates in keratinocytes via metal-catalyzed cleavage of the peroxide bond resulting in the formation of the benzoyloxyl radical. Covalent modification of DNA was not observed when [ 14 C]BzPO was incubated with calf thymus DNA in the presence of copper. Overall, these results suggest that BzPO induces DNA damage via benzoyloxyl radical mediated proton abstraction from the DNA strand and the adduct formation with DNA is unlikely to occur

  11. Mild Oxidative Damage in the Diabetic Rat Heart Is Attenuated by Glyoxalase-1 Overexpression

    Directory of Open Access Journals (Sweden)

    Casper G. Schalkwijk

    2013-07-01

    Full Text Available Diabetes significantly increases the risk of heart failure. The increase in advanced glycation endproducts (AGEs and oxidative stress have been associated with diabetic cardiomyopathy. We recently demonstrated that there is a direct link between AGEs and oxidative stress. Therefore, the aim of the current study was to investigate if a reduction of AGEs by overexpression of the glycation precursor detoxifying enzyme glyoxalase-I (GLO-I can prevent diabetes-induced oxidative damage, inflammation and fibrosis in the heart. Diabetes was induced in wild-type and GLO-I transgenic rats by streptozotocin. After 24-weeks of diabetes, cardiac function was monitored with ultrasound under isoflurane anesthesia. Blood was drawn and heart tissue was collected for further analysis. Analysis with UPLC-MSMS showed that the AGE Nε-(1-carboxymethyllysine and its precursor 3-deoxyglucosone were significantly elevated in the diabetic hearts. Markers of oxidative damage, inflammation, and fibrosis were mildly up-regulated in the heart of the diabetic rats and were attenuated by GLO-I overexpression. In this model of diabetes, these processes were not accompanied by significant changes in systolic heart function, i.e., stroke volume, fractional shortening and ejection fraction. This study shows that 24-weeks of diabetes in rats induce early signs of mild cardiac alterations as indicated by an increase of oxidative stress, inflammation and fibrosis which are mediated, at least partially, by glycation.

  12. Roles of ROS mediated oxidative stress and DNA damage in 3-methyl-2-quinoxalin benzenevinylketo-1, 4-dioxide-induced immunotoxicity of Sprague-Dawley rats.

    Science.gov (United States)

    Gao, Hui; Wang, Di; Zhang, Shun; Xu, Mengjing; Yang, Wei; Yan, Peipei; Liu, Yang; Luo, Xiao; Wu, Hailei; Yao, Ping; Yan, Hong; Liu, Liegang

    2015-11-01

    3-methyl-2-quinoxalin benzenevinylketo-1, 4-dioxide (Quinocetone, QCT) has been broadly used to treat dysentery and promote animal growth in food producing animals. However, its potential toxicity could not been neglected as parts of safety assessment according to the acceptable guidelines for QCT administration. In this study, the immunotoxicity of QCT was investigated in male Sprague-Dawley (SD) rats following a 28-day oral exposure at doses of 0, 50, 800, and 2400 mg/kg/day. The food consumption, body weight gain and relative spleen weight were significantly decreased by QCT in a dose-dependent manner. Treatment of rats with QCT also notably suppressed the T-cell proliferation and natural killer (NK) cell activity, accompanied by intracellular reactive oxygen species (ROS) accumulation, antioxidant system inhibition and DNA damage enhancement. Thus, the primary finding of this study is that QCT exposure (2400 mg/kg/day) could cause immunotoxicity in SD rats due to ROS mediated oxidative stress and DNA damage. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Iron release from ferritin and lipid peroxidation by radiolytically generated reducing radicals

    International Nuclear Information System (INIS)

    Reif, D.W.; Schubert, J.; Aust, S.D.

    1988-01-01

    Iron is involved in the formation of oxidants capable of damaging membranes, protein, and DNA. Using 137 Cs gamma radiation, we investigated the release of iron from ferritin and concomitant lipid peroxidation by radiolytically generated reducing radicals, superoxide and the carbon dioxide anion radical. Both radicals released iron from ferritin with similar efficiencies and iron mobilization from ferritin required an iron chelator. Radiolytically generated superoxide anion resulted in peroxidation of phospholipid liposomes as measured by malondialdehyde formation only when ferritin was included as an iron source and the released iron was found to be chelated by the phospholipid liposomes

  14. Pulse radiolysis investigations on the oxidation of bilirubin by chlorinated peroxyl radicals (Preprint No. RC.18)

    International Nuclear Information System (INIS)

    Mohan, Hari; Gopinathan, C.

    1989-01-01

    Chlorinated peroxyl radicals were observed to oxidize bilirubin. The rate constants, estimated from the formation kinetics of bilirubin cation, were observed to decrease with decrease in the chlorine substitution of various chlorinated peroxyl radicals. (author)

  15. Over-expression of heme oxygenase-1 promotes oxidative mitochondrial damage in rat astroglia.

    Science.gov (United States)

    Song, Wei; Su, Haixiang; Song, Sisi; Paudel, Hemant K; Schipper, Hyman M

    2006-03-01

    Glial heme oxygenase-1 is over-expressed in the CNS of subjects with Alzheimer disease (AD), Parkinson disease (PD) and multiple sclerosis (MS). Up-regulation of HO-1 in rat astroglia has been shown to facilitate iron sequestration by the mitochondrial compartment. To determine whether HO-1 induction promotes mitochondrial oxidative stress, assays for 8-epiPGF(2alpha) (ELISA), protein carbonyls (ELISA) and 8-OHdG (HPLC-EC) were used to quantify oxidative damage to lipids, proteins, and nucleic acids, respectively, in mitochondrial fractions and whole-cell compartments derived from cultured rat astroglia engineered to over-express human (h) HO-1 by transient transfection. Cell viability was assessed by trypan blue exclusion and the MTT assay, and cell proliferation was determined by [3H] thymidine incorporation and total cell counts. In rat astrocytes, hHO-1 over-expression (x 3 days) resulted in significant oxidative damage to mitochondrial lipids, proteins, and nucleic acids, partial growth arrest, and increased cell death. These effects were attenuated by incubation with 1 microM tin mesoporphyrin, a competitive HO inhibitor, or the iron chelator, deferoxamine. Up-regulation of HO-1 engenders oxidative mitochondrial injury in cultured rat astroglia. Heme-derived ferrous iron and carbon monoxide (CO) may mediate the oxidative modification of mitochondrial lipids, proteins and nucleic acids in these cells. Glial HO-1 hyperactivity may contribute to cellular oxidative stress, pathological iron deposition, and bioenergetic failure characteristic of degenerating and inflamed neural tissues and may constitute a rational target for therapeutic intervention in these conditions. Copyright 2005 Wiley-Liss, Inc.

  16. Hormonal shifts and intensity of free radical oxidation in the blood of patients with facial nerve neuropathies

    Directory of Open Access Journals (Sweden)

    L. V. Govorova

    2010-01-01

    Full Text Available Pathochemical characteristic features of facial nerve neuropathy (FNN have been more accurately defined. Heterogeneous patochemical pattern of facial nerve neuropathy has been shown to be dependent on the severity of the disease, intensity of free radical oxidation processes, and hormonal status of the patient. We have found reliable distinctions in dynamics of free radical oxidation processes, and hormo-nal status in the blood of the patients with moderately severe and severe forms of facial nerve neuropathies. In facial nerve neuropathies we observed regulatory effects of cortisol and somatotropic hormone; in facial nerve neuropathywith moderate severity the hormones of thyroid group were seen to be switching off, falling out the processes regulating metabolism. Follicle stimulating hormone (FSH and luteinizing hormone (LH were found to have regulating effects, especially in the acute phase of the disease. Different dynamics of the hormones in patients with high and low free radical oxidation levels suggests that the oxidative stress intensity could be associated with regulatory effects of the hormones . The results of correlation analysis confirm the reliable distinctions in free radical oxidation characteristics andand cortisole levels, STH, FSH and LH levels.

  17. Radical Decisions in Cancer: Redox Control of Cell Growth and Death

    International Nuclear Information System (INIS)

    Sainz, Rosa M.; Lombo, Felipe; Mayo, Juan C.

    2012-01-01

    Free radicals play a key role in many physiological decisions in cells. Since free radicals are toxic to cellular components, it is known that they cause DNA damage, contribute to DNA instability and mutation and thus favor carcinogenesis. However, nowadays it is assumed that free radicals play a further complex role in cancer. Low levels of free radicals and steady state levels of antioxidant enzymes are responsible for the fine tuning of redox status inside cells. A change in redox state is a way to modify the physiological status of the cell, in fact, a more reduced status is found in resting cells while a more oxidative status is associated with proliferative cells. The mechanisms by which redox status can change the proliferative activity of cancer cells are related to transcriptional and posttranscriptional modifications of proteins that play a critical role in cell cycle control. Since cancer cells show higher levels of free radicals compared with their normal counterparts, it is believed that the anti-oxidative stress mechanism is also increased in cancer cells. In fact, the levels of some of the most important antioxidant enzymes are elevated in advanced status of some types of tumors. Anti-cancer treatment is compromised by survival mechanisms in cancer cells and collateral damage in normal non-pathological tissues. Though some resistance mechanisms have been described, they do not yet explain why treatment of cancer fails in several tumors. Given that some antitumoral treatments are based on the generation of free radicals, we will discuss in this review the possible role of antioxidant enzymes in the survival mechanism in cancer cells and then, its participation in the failure of cancer treatments

  18. NEIL2 protects against oxidative DNA damage induced by sidestream smoke in human cells.

    Directory of Open Access Journals (Sweden)

    Altaf H Sarker

    Full Text Available Secondhand smoke (SHS is a confirmed lung carcinogen that introduces thousands of toxic chemicals into the lungs. SHS contains chemicals that have been implicated in causing oxidative DNA damage in the airway epithelium. Although DNA repair is considered a key defensive mechanism against various environmental attacks, such as cigarette smoking, the associations of individual repair enzymes with susceptibility to lung cancer are largely unknown. This study investigated the role of NEIL2, a DNA glycosylase excising oxidative base lesions, in human lung cells treated with sidestream smoke (SSS, the main component of SHS. To do so, we generated NEIL2 knockdown cells using siRNA-technology and exposed them to SSS-laden medium. Representative SSS chemical compounds in the medium were analyzed by mass spectrometry. An increased production of reactive oxygen species (ROS in SSS-exposed cells was detected through the fluorescent detection and the induction of HIF-1α. The long amplicon-quantitative PCR (LA-QPCR assay detected significant dose-dependent increases of oxidative DNA damage in the HPRT gene of cultured human pulmonary fibroblasts (hPF and BEAS-2B epithelial cells exposed to SSS for 24 h. These data suggest that SSS exposure increased oxidative stress, which could contribute to SSS-mediated toxicity. siRNA knockdown of NEIL2 in hPF and HEK 293 cells exposed to SSS for 24 h resulted in significantly more oxidative DNA damage in HPRT and POLB than in cells with control siRNA. Taken together, our data strongly suggest that decreased repair of oxidative DNA base lesions due to an impaired NEIL2 expression in non-smokers exposed to SSS would lead to accumulation of mutations in genomic DNA of lung cells over time, thus contributing to the onset of SSS-induced lung cancer.

  19. Oxidative Stress and Anesthesia in Diabetic Patients

    Directory of Open Access Journals (Sweden)

    Peivandi Yazdi A

    2014-04-01

    Full Text Available Free radical and peroxide production lead to intracellular damage. On the other hand, free radicals are used by the human immune system to defend against pathogens. The aging process could be limited by oxidative stress in the short term. Chronic diseases like diabetes mellitus (DM are full-stress conditions in which remarkable metabolic functional destructions might happen. There is strong evidence regarding antioxidant impairment in diabetes. Performing a particular method for anesthesia in diabetic patients might prevent or modify excessive free radical formation and oxidative stress. It seems that prescribing antioxidant drugs could promote wound healing in diabetics.  

  20. Hawkmoths use nectar sugar to reduce oxidative damage from flight.

    Science.gov (United States)

    Levin, E; Lopez-Martinez, G; Fane, B; Davidowitz, G

    2017-02-17

    Nectar-feeding animals have among the highest recorded metabolic rates. High aerobic performance is linked to oxidative damage in muscles. Antioxidants in nectar are scarce to nonexistent. We propose that nectarivores use nectar sugar to mitigate the oxidative damage caused by the muscular demands of flight. We found that sugar-fed moths had lower oxidative damage to their flight muscle membranes than unfed moths. Using respirometry coupled with δ 13 C analyses, we showed that moths generate antioxidant potential by shunting nectar glucose to the pentose phosphate pathway (PPP), resulting in a reduction in oxidative damage to the flight muscles. We suggest that nectar feeding, the use of PPP, and intense exercise are causally linked and have allowed the evolution of powerful fliers that feed on nectar. Copyright © 2017, American Association for the Advancement of Science.

  1. OXIDATIVE STRESS AND VASCULAR DAMAGE IN HYPOXIA PROCESSES. MALONDIALDEHYDE (MDA AS BIOMARKER FOR OXIDATIVE DAMAGE

    Directory of Open Access Journals (Sweden)

    Muñiz P

    2014-05-01

    Full Text Available Changes in the levels oxidative stress biomarkers are related with different diseases such as ischemia/reperfusion, cardiovascular, renal, aging, etc. One of these biomarkers is the malondialdehyde (MDA generated as resulted of the process of lipid peroxidation. This biomarker is increased under conditions of the oxidative stress. Their levels, have been frequently used to measure plasma oxidative damage to lipids by their atherogenic potential. Its half-life high and their reactivity allows it to act both inside and outside of cells and interaction with proteins and DNA involve their role in different pathophysiological processes. This paper presents an analysis of the use of MDA as a biomarker of oxidative stress and its implications associated pathologies such as cardiovascular diseases ago.

  2. Oxidation flux change on spermatozoa membrane in important pathologic conditions leading to male infertility.

    Science.gov (United States)

    Wiwanitkit, V

    2008-06-01

    Free radicals or reactive oxygen species mediate their action through proinflammatory cytokines and this mechanism has been proposed as a common underlying factor for male infertility. There is extensive literature on oxidative stress and its role in male infertility and sperm DNA damage and its effects on assisted reproductive techniques. However, there has never been a report on the oxidation flux change in spermatozoa. Here, the author determined the oxidation flux change in such hypoxic cases, using the simulation test based on nanomedicine technique is used. Of interest, change of flux can be detected. The main pathogenesis should be the direct injury of membrane structure of spermatozoa by free radicals which can lead to sperm defect. Therefore, this work can support the finding that the oxidation flux change corresponding to oxygen pressure change in spermatozoa does not exist. However, the flux change can be seen if the membrane thickness of spermatozoa is varied. Thin membrane spermatozoa are more prone to oxidative stress than thick membrane ones. The defect in the enzymatic system within the spermatozoa should be a better explanation for vulnerability of spermatozoa to oxidative stress. The use of enzymatic modification technique by antioxidants can be useful alternative in management of male infertility.

  3. Lycopene Protects the Diabetic Rat Kidney Against Oxidative Stress-mediated Oxidative Damage Induced by Furan

    Directory of Open Access Journals (Sweden)

    Dilek Pandir

    2016-01-01

    Full Text Available Furan is a food and environmental contaminant and a potent carcinogen in animals. Lycopene is one dietary carotenoid found in fruits such as tomato, watermelon and grapefruit. The present study was designed to explore the protective effect of lycopene against furan-induced oxidative damage in streptozotocin (STZ-induced diabetic rat kidney. At the end of the experimental period (28 days, we found that lycopene markedly decreased the malondialdehide (MDA levels in the kidney, urea, uric acid and creatinine levels in the serum of furan-treated rats. The increase of histopathology in the kidney of furan-treated rats were effectively suppressed by lycopene. Furthermore, lycopene markedly restored superoxide dismutase (SOD, catalase (CAT, glutathione peroxidase (GPx and glutathione-S-transferase (GST activities in the kidney of furan-treated rats. In conclusion, these results suggested that lycopene could protect the rat kidney against furan-induced injury by improving renal function, attenuating histopathologic changes, reducing MDA production and renewing the activities of antioxidant enzymes.

  4. Aspects of reaction of N-oxide radical with ethers in 13C NMR spectrum

    International Nuclear Information System (INIS)

    Kolodziejski, W.

    1980-01-01

    The stable radical N-oxide 2,2,6,6-tetramethylpiperidine was dissolved in ethers. The 13 C NMR spectra were recorded in the temperature 313K at the frequency 22,625 MHz on the spectrometers with Fourier transformation. The dissolution of the radical in ether caused the contact shifts in NMR spectra. The shifts were measured. (A.S.)

  5. Increased oxidative DNA damage in mononuclear leukocytes in vitiligo

    Energy Technology Data Exchange (ETDEWEB)

    Giovannelli, Lisa [Department of Preclinical and Clinical Pharmacology, University of Florence, Viale Pieraccini 6, 50139 Florence (Italy)]. E-mail: lisag@pharm.unifi.it; Bellandi, Serena [Department of Dermatological Sciences, University of Florence, Viale Pieraccini 6, 50139 Florence (Italy); Pitozzi, Vanessa [Department of Preclinical and Clinical Pharmacology, University of Florence, Viale Pieraccini 6, 50139 Florence (Italy); Fabbri, Paolo [Department of Dermatological Sciences, University of Florence, Viale Pieraccini 6, 50139 Florence (Italy); Dolara, Piero [Department of Preclinical and Clinical Pharmacology, University of Florence, Viale Pieraccini 6, 50139 Florence (Italy); Moretti, Silvia [Department of Dermatological Sciences, University of Florence, Viale Pieraccini 6, 50139 Florence (Italy)

    2004-11-22

    Vitiligo is an acquired pigmentary disorder of the skin of unknown aetiology. The autocytotoxic hypothesis suggests that melanocyte impairment could be related to increased oxidative stress. Evidences have been reported that in vitiligo oxidative stress might also be present systemically. We used the comet assay (single cell alkaline gel electrophoresis) to evaluate DNA strand breaks and DNA base oxidation, measured as formamidopyrimidine DNA glycosylase (FPG)-sensitive sites, in peripheral blood cells from patients with active vitiligo and healthy controls. The basal level of oxidative DNA damage in mononuclear leukocytes was increased in vitiligo compared to normal subjects, whereas DNA strand breaks (SBs) were not changed. This alteration was not accompanied by a different capability to respond to in vitro oxidative challenge. No differences in the basal levels of DNA damage in polymorphonuclear leukocytes were found between patients and healthy subjects. Thus, this study supports the hypothesis that in vitiligo a systemic oxidative stress exists, and demonstrates for the first time the presence of oxidative alterations at the nuclear level. The increase in oxidative DNA damage shown in the mononuclear component of peripheral blood leukocytes from vitiligo patients was not particularly severe. However, these findings support an adjuvant role of antioxidant treatment in vitiligo.

  6. Increased oxidative DNA damage in mononuclear leukocytes in vitiligo

    International Nuclear Information System (INIS)

    Giovannelli, Lisa; Bellandi, Serena; Pitozzi, Vanessa; Fabbri, Paolo; Dolara, Piero; Moretti, Silvia

    2004-01-01

    Vitiligo is an acquired pigmentary disorder of the skin of unknown aetiology. The autocytotoxic hypothesis suggests that melanocyte impairment could be related to increased oxidative stress. Evidences have been reported that in vitiligo oxidative stress might also be present systemically. We used the comet assay (single cell alkaline gel electrophoresis) to evaluate DNA strand breaks and DNA base oxidation, measured as formamidopyrimidine DNA glycosylase (FPG)-sensitive sites, in peripheral blood cells from patients with active vitiligo and healthy controls. The basal level of oxidative DNA damage in mononuclear leukocytes was increased in vitiligo compared to normal subjects, whereas DNA strand breaks (SBs) were not changed. This alteration was not accompanied by a different capability to respond to in vitro oxidative challenge. No differences in the basal levels of DNA damage in polymorphonuclear leukocytes were found between patients and healthy subjects. Thus, this study supports the hypothesis that in vitiligo a systemic oxidative stress exists, and demonstrates for the first time the presence of oxidative alterations at the nuclear level. The increase in oxidative DNA damage shown in the mononuclear component of peripheral blood leukocytes from vitiligo patients was not particularly severe. However, these findings support an adjuvant role of antioxidant treatment in vitiligo

  7. Coagulin-L ameliorates TLR4 induced oxidative damage and immune response by regulating mitochondria and NOX-derived ROS

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, Sukka Santosh [Pharmacology Division, CSIR-Central Drug Research Institute, Lucknow 226031 (India); Chauhan, Parul [Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031 (India); Maurya, Preeti [Pharmacology Division, CSIR-Central Drug Research Institute, Lucknow 226031 (India); Academy of Scientific and Innovative Research, New Delhi 110025 (India); Saini, Deepika [Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031 (India); Yadav, Prem Prakash, E-mail: pp_yadav@cdri.res.in [Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031 (India); Barthwal, Manoj Kumar, E-mail: manojbarthwal@cdri.res.in [Pharmacology Division, CSIR-Central Drug Research Institute, Lucknow 226031 (India)

    2016-10-15

    Withanolides possess diverse biological and pharmacological activity but their immunomodulatory function is less realized. Hence, coagulin-L, a withanolide isolated from Withania coagulans Dunal has been studied for such an effect in human and murine cells, and mice model. Coagulin-L (1, 3, 10 μM) exhibited immunomodulatory effect by suppressing TLR4 induced immune mediators such as cytokines (GMCSF, IFNα, IFNγ, IL-1α, IL-1Rα, IL-1β, IL-2, IL-2R, IL-4, IL-5, IL-6, IL-7, IL-10, IL-12 (p40/p70), IL-13, IL-15, IL-17), chemokines (IL-8/CXCL8, MIG/CXCL9, IP-10/CXCL10, KC, MCP-1/CCL2, MIP-1α/CCL3, MIP-1β/CCL4, RANTES/CCL5, eotaxin/CCL11), growth factors (FGF-basic, VEGF), nitric oxide and intracellular superoxide. Mechanistically, coagulin-L abrogated LPS induced total and mitochondrial ROS generation, NOX2, NOX4 mRNA expression, IRAK and MAPK (p38, JNK, ERK) activation. Coagulin-L also attenuated IκBα degradation, which prevented NFκB downstream iNOS expression and pro-inflammatory cytokine release. Furthermore, coagulin-L (10, 25, 50 mg/kg, p.o.), undermined the LPS (10 mg/kg, i.p.) induced endotoxemia response in mice as evinced from diminished cytokine release, nitric oxide, aortic p38 MAPK activation and endothelial tissue impairment besides suppressing NOX2 and NOX4 expression in liver and aorta. Moreover, coagulin-L also alleviated the ROS mediated oxidative damage which was assessed through protein carbonyl, lipid hydroperoxide, 8-isoprostane and 8-hydroxy-2-deoxyguanosine quantification. To extend, coagulin-L also suppressed carrageenan-induced paw edema and thioglycollate-induced peritonitis in mice. Therefore, coagulin-L can be of therapeutic importance in pathological conditions induced by oxidative damage. - Highlights: • Coagulin-L demonstrates immunomodulatory effects in vivo and in vitro by modulating ROS. • Coagulin-L modulates TH1/TH2/TH17 immunokines. • Coagulin-L exerts immunomodulatory effect by regulating TLR4-IRAK- ROS

  8. Free Radicals and Extrinsic Skin Aging

    Directory of Open Access Journals (Sweden)

    Borut Poljšak

    2012-01-01

    Full Text Available Human skin is constantly directly exposed to the air, solar radiation, environmental pollutants, or other mechanical and chemical insults, which are capable of inducing the generation of free radicals as well as reactive oxygen species (ROS of our own metabolism. Extrinsic skin damage develops due to several factors: ionizing radiation, severe physical and psychological stress, alcohol intake, poor nutrition, overeating, environmental pollution, and exposure to UV radiation (UVR. It is estimated that among all these environmental factors, UVR contributes up to 80%. UV-induced generation of ROS in the skin develops oxidative stress, when their formation exceeds the antioxidant defence ability of the target cell. The primary mechanism by which UVR initiates molecular responses in human skin is via photochemical generation of ROS mainly formation of superoxide anion (O2−•, hydrogen peroxide (H2O2, hydroxyl radical (OH•, and singlet oxygen (1O2. The only protection of our skin is in its endogenous protection (melanin and enzymatic antioxidants and antioxidants we consume from the food (vitamin A, C, E, etc.. The most important strategy to reduce the risk of sun UVR damage is to avoid the sun exposure and the use of sunscreens. The next step is the use of exogenous antioxidants orally or by topical application and interventions in preventing oxidative stress and in enhanced DNA repair.

  9. New insights into the aquatic photochemistry of fluoroquinolone antibiotics: Direct photodegradation, hydroxyl-radical oxidation, and antibacterial activity changes

    International Nuclear Information System (INIS)

    Ge, Linke; Na, Guangshui; Zhang, Siyu; Li, Kai; Zhang, Peng; Ren, Honglei; Yao, Ziwei

    2015-01-01

    The ubiquity and photoreactivity of fluoroquinolone antibiotics (FQs) in surface waters urge new insights into their aqueous photochemical behavior. This study concerns the photochemistry of 6 FQs: ciprofloxacin, danofloxacin, levofloxacin, sarafloxacin, difloxacin and enrofloxacin. Methods were developed to calculate their solar direct photodegradation half-lives (t d,E ) and hydroxyl-radical oxidation half-lives (t ·OH,E ) in sunlit surface waters. The t d,E values range from 0.56 min to 28.8 min at 45° N latitude, whereas t ·OH,E ranges from 3.24 h to 33.6 h, suggesting that most FQs tend to undergo fast direct photolysis rather than hydroxyl-radical oxidation in surface waters. However, a case study for levofloxacin and sarafloxacin indicated that the hydroxyl-radical oxidation induced risky photochlorination and resulted in multi-degradation pathways, such as piperazinyl hydroxylation and clearage. Changes in the antibacterial activity of FQs caused by photodegradation in various waters were further examined using Escherichia coli, and it was found that the activity evolution depended on primary photodegradation pathways and products. Primary intermediates with intact FQ nuclei retained significant antibacterial activity. These results are important for assessing the fate and risk of FQs in surface waters. - Highlights: • It is first reported on hydroxyl-radical oxidation of 6 fluoroquinolone antibiotics. • Methods were developed to assess photolysis and oxidation fate in surface waters. • The neutral form reacted faster with hydroxyl radical than protonated forms. • The main oxidation intermediates and transformation pathways were clarified. • The antibacterial activity changes depend on dominant photolysis pathways

  10. Sulfur isotope fractionation during oxidation of sulfur dioxide: gas-phase oxidation by OH radicals and aqueous oxidation by H2O2, O3 and iron catalysis

    Directory of Open Access Journals (Sweden)

    J. N. Crowley

    2012-01-01

    Full Text Available The oxidation of SO2 to sulfate is a key reaction in determining the role of sulfate in the environment through its effect on aerosol size distribution and composition. Sulfur isotope analysis has been used to investigate sources and chemical processes of sulfur dioxide and sulfate in the atmosphere, however interpretation of measured sulfur isotope ratios is challenging due to a lack of reliable information on the isotopic fractionation involved in major transformation pathways. This paper presents laboratory measurements of the fractionation factors for the major atmospheric oxidation reactions for SO2: Gas-phase oxidation by OH radicals, and aqueous oxidation by H2O2, O3 and a radical chain reaction initiated by iron. The measured fractionation factor for 34S/32S during the gas-phase reaction is αOH = (1.0089±0.0007−((4±5×10−5 T(°C. The measured fractionation factor for 34S/32S during aqueous oxidation by H2O2 or O3 is αaq = (1.0167±0.0019−((8.7±3.5 ×10−5T(°C. The observed fractionation during oxidation by H2O2 and O3 appeared to be controlled primarily by protonation and acid-base equilibria of S(IV in solution, which is the reason that there is no significant difference between the fractionation produced by the two oxidants within the experimental error. The isotopic fractionation factor from a radical chain reaction in solution catalysed by iron is αFe = (0.9894±0.0043 at 19 °C for 34S/32S. Fractionation was mass-dependent with regards to 33S/32S for all the reactions investigated. The radical chain reaction mechanism was the only measured reaction that had a faster rate for the light isotopes. The results presented in this study will be particularly useful to determine the importance of the transition metal-catalysed oxidation pathway compared to other oxidation pathways, but other main oxidation pathways can not be distinguished based on stable sulfur isotope measurements alone.

  11. Oxidative stress damage as a detrimental factor in preterm birth pathology.

    Science.gov (United States)

    Menon, Ramkumar

    2014-01-01

    Normal term and spontaneous preterm births (PTB) are documented to be associated with oxidative stress (OS), and imbalances in the redox system (balance between pro- and antioxidant) have been reported in the maternal-fetal intrauterine compartments. The exact mechanism of labor initiation either at term or preterm by OS is still unclear, and this lack of understanding can partially be blamed for failure of antioxidant supplementation trials in PTB prevention. Based on recent findings from our laboratory, we postulate heterogeneity in host OS response. The physiologic (at term) and pathophysiologic (preterm) pathways of labor are not mediated by OS alone but by OS-induced damage to intrauterine tissues, especially fetal membranes of the placenta. OS damage affects all major cellular elements in the fetal cells, and this damage promotes fetal cell senescence (aging). The aging of the fetal cells is predominated by p38 mitogen activated kinase (p38MAPK) pathways. Senescing cells generate biomolecular signals that are uterotonic, triggering labor process. The aging of fetal cells is normal at term. However, aging is premature in PTB, especially in those PTBs complicated by preterm premature rupture of the membranes, where elements of redox imbalances and OS damage are more dominant. We postulate that fetal cell senescence signals generated by OS damage are likely triggers for labor. This review highlights the mechanisms involved in senescence development at term and preterm by OS damage and provides insight into novel fetal signals of labor initiation pathways.

  12. Antitumor potential induction and free radicals production in melanoma cells by Boron Neutron Capture Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Faiao-Flores, F. [Biochemical and Biophysical Laboratory, Butantan Institute, 1500 Vital Brasil Avenue, Sao Paulo (Brazil)] [Faculty of Medicine, University of Sao Paulo, 455 Doutor Arnaldo Avenue, Sao Paulo (Brazil); Coelho, P.R.P.; Muniz, R.O.R.; Souza, G.S. [Institute for Nuclear and Energy Research, 2242 Lineu Prestes Avenue, Sao Paulo (Brazil); Arruda-Neto, J. [Physics Institute, University of Sao Paulo, 187 Matao Street, Sao Paulo (Brazil)] [FESP, Sao Paulo Engineering School, 5520 Nove de Julho Avenue, Sao Paulo (Brazil); Maria, Durvanei A., E-mail: durvaneiaugusto@yahoo.com.br [Biochemical and Biophysical Laboratory, Butantan Institute, 1500 Vital Brasil Avenue, Sao Paulo (Brazil)

    2011-12-15

    Antiproliferative and oxidative damage effects occurring in Boron Neutron Capture Therapy (BNCT) in normal fibroblasts and melanoma cell lines were analyzed. Melanoma cells and normal fibroblasts were treated with different concentrations of Boronophenylalanine and irradiated with thermal neutron flux. The cellular viability and the oxidative stress were determined. BNCT induced free radicals production and proliferative potential inhibition in melanoma cells. Therefore, this therapeutic technique could be considered efficient to inhibit growth of melanoma with minimal effects on normal tissues. - Highlights: Black-Right-Pointing-Pointer Boron Neutron Capture Therapy (BNCT) induces melanoma cell death. Black-Right-Pointing-Pointer BNCT stimulates free radicals production and proliferative inhibition in melanoma cells. Black-Right-Pointing-Pointer It produces tumor membrane degeneration and destruction with apoptotic bodies formation. Black-Right-Pointing-Pointer This therapy damages tumor cells selectively, with minimum effects on normal adjacent tissue.

  13. In vivo imaging of free radicals produced by multivitamin-mineral supplements

    Science.gov (United States)

    Buettner, Garry R.; Fink, Bruno

    2015-01-01

    Background Redox active minerals in dietary supplements can catalyze unwanted and potentially harmful oxidations. Methods To determine if this occurs in vivo we employed electron paramagnetic (EPR) imaging. We used 1-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine (CPH) as a reporter for one-electron oxidations, e.g. free radical-mediated oxidations; the one-electron oxidation product of CPH, 3-carboxy-2,2,5,5-tetramethyl-1-pyrrolidinyloxy (CP•), is a nitroxide free radical that is relatively persistent in vivo and detectable by EPR. As model systems, we used research formulations of vitamin mineral supplements (RVM) that are typical of commercial products. Results In in vitro experiments, upon suspension of RVM in aqueous solution, we observed: (1) the uptake of oxygen in the solution, consistent with oxidation of the components in the RVM; (2) the ascorbate free radical, a real-time indicator of ongoing oxidations; and (3) when amino acid/oligosaccharide (AAOS; glycinate or aspartate with non-digestible oligofructose) served as the matrix in the RVM, the rate of oxidation was significantly slowed. In a murine model, EPR imaging showed that the ingestion of RVM along with CPH results in the one-electron oxidation of CPH by RVM in the digestive system. The resulting CP• distributes throughout the body. Inclusion of AAOS in the RVM formulation diminished the oxidation of CPH to CP• in vivo. Conclusions These data demonstrate that typical formulations of multivitamin/multimineral dietary supplements can initiate the oxidation of bystander substances and that AAOS-complexes of essential redox active metals, e.g. copper and iron, have reduced ability to catalyze free radical formation and associated detrimental oxidations when a part of a multivitamin/multimineral formulation. PMID:26705481

  14. Toll-Like Receptor-Mediated Free Radical Generation in Clonorchis sinensis Excretory-Secretory Product-Treated Cholangiocarcinoma Cells.

    Science.gov (United States)

    Bahk, Young Yil; Pak, Jhang Ho

    2016-10-01

    Clonorchiasis, caused by direct contact with Clonorchis sinensis worms and their excretory-secretory products (ESPs), is associated with chronic inflammation, malignant changes in bile ducts, and even cholangiocarcinogenesis. Our previous report revealed that intracellular free radicals enzymatically generated by C. sinensis ESPs cause NF-κB-mediated inflammation in human cholangiocarcinoma cells (HuCCT1). Therefore, the present study was conducted to examine the role of upstream Toll-like receptors (TLRs) on the initial host innate immune responses to infection. We found that treatment of HuCCT1 cells with native ESPs induced changes in TLR mRNA levels in a time-dependent manner, concomitant with the generation of free radicals. ESP-mediated free radical generation was markedly attenuated by preincubation of the cells with TLR1-4-neutralizing antibodies, indicating that at least TLR1 through 4 participate in stimulation of the host innate immune responses. These findings indicate that free radicals triggered by ESPs are critically involved in TLR signal transduction. Continuous signaling by this pathway may function in initiating C. sinensis infection-associated inflammation cascades, a detrimental event leading to progression to more severe hepatobiliary diseases.

  15. Development of sensors for monitoring oxygen and free radicals in plant physiology

    Science.gov (United States)

    Chaturvedi, Prachee

    Oxygen plays a critical role in the physiology of photosynthetic organisms, including bioenergetics, metabolism, development, and stress response. Oxygen levels affect photosynthesis, respiration, and alternative oxidase pathways. Likewise, the metabolic rate of spatially distinct plant cells (and therefore oxygen flux) is known to be affected by biotic stress (e.g., herbivory) and environmental stress (e.g., salt/nutrient stress). During aerobic metabolism, cells produce reactive oxygen species (ROS) as a by product. Plants also produce ROS during adaptation to stress (e.g., abscisic acid (ABA) mediated stress responses). If stress conditions are prolonged, ROS levels surpass the capacity of detoxifying mechanisms within the cell, resulting in oxidative damage. While stress response pathways such as ABA-mediated mechanisms have been well characterized (e.g., water stress, inhibited shoot growth, synthesis of storage proteins in seeds), the connection between ROS production, oxygen metabolism and stress response remains unknown. In part, this is because details of oxygen transport at the interface of cell(s) and the surrounding microenvironment remains nebulous. The overall goal of this research was to develop oxygen and Free radical sensors for studying stress signaling in plants. Recent developments in nanomaterials and data acquisition systems were integrated to develop real-time, non-invasive oxygen and Free radical sensors. The availability of these sensors for plant physiologists is an exciting opportunity to probe the functional realm of cells and tissues in ways that were not previously possible.

  16. Characterization of 60 Co y-radiation induced radical products of antipyrine by means of high performance liquid chromatography, mass spectrometry, capillary zone electrophoresis, micellar electrokinetic capillary chromatography and nuclear magnetic resonance spectrometry

    NARCIS (Netherlands)

    Coolen, S.A.J.; Everaerts, F.M.; Huf, F.A.

    1997-01-01

    Monitoring the amount of oxidative damage, caused by free radicals, is a major problem in free radical and aging research. Antipyrine is proposed as an exogenous marker for the biomolecular monitoring of oxidative stress. In this paper the characterization of the 60Co γ-radiation products of

  17. Characterization of 60Co gamma-radiation induced radical products of antipyrine by means of high-performance liquid chromatography, mass spectrometry, capillary zone electrophoresis, micellar electrokinetic capillary chromatography and nuclear magnetic resonance spectrometry

    NARCIS (Netherlands)

    Coolen, S.A.J.; Everaerts, F.M.; Huf, F.A.

    1997-01-01

    Monitoring the amount of oxidative damage, caused by free radicals, is a major problem in free radical and aging research. Antipyrine is proposed as an exogenous marker for the biomolecular monitoring of oxidative stress. In this paper the characterization of the 60Co ¿-radiation products of

  18. Oxidative DNA damage and mammary cell proliferation by alcohol-derived salsolinol.

    Science.gov (United States)

    Murata, Mariko; Midorikawa, Kaoru; Kawanishi, Shosuke

    2013-10-21

    Drinking alcohol is a risk factor for breast cancer. Salsolinol (SAL) is endogenously formed by a condensation reaction of dopamine with acetaldehyde, a major ethanol metabolite, and SAL is detected in blood and urine after alcohol intake. We investigated the possibility that SAL can participate in tumor initiation and promotion by causing DNA damage and cell proliferation, leading to alcohol-associated mammary carcinogenesis. SAL caused oxidative DNA damage including 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), in the presence of transition metal ions, such as Cu(II) and Fe(III)EDTA. Inhibitory effects of scavengers on SAL-induced DNA damage and the electron spin resonance study indicated the involvement of H₂O₂, which is generated via the SAL radical. Experiments on scavengers and site specificity of DNA damage suggested ·OH generation via a Fenton reaction and copper-peroxide complexes in the presence of Fe(III)EDTA and Cu(II), respectively. SAL significantly increased 8-oxodG formation in normal mammary epithelial MCF-10A cells. In addition, SAL induced cell proliferation in estrogen receptor (ER)-negative MCF-10A cells, and the proliferation was inhibited by an antioxidant N-acetylcysteine and an epidermal growth factor receptor (EGFR) inhibitor AG1478, suggesting that reactive oxygen species may participate in the proliferation of MCF-10A cells via EGFR activation. Furthermore, SAL induced proliferation in estrogen-sensitive breast cancer MCF-7 cells, and a surface plasmon resonance sensor revealed that SAL significantly increased the binding activity of ERα to the estrogen response element but not ERβ. In conclusion, SAL-induced DNA damage and cell proliferation may play a role in tumor initiation and promotion of multistage mammary carcinogenesis in relation to drinking alcohol.

  19. Lymphocyte DNA damage and oxidative stress in patients with iron deficiency anemia.

    Science.gov (United States)

    Aslan, Mehmet; Horoz, Mehmet; Kocyigit, Abdurrahim; Ozgonül, Saadet; Celik, Hakim; Celik, Metin; Erel, Ozcan

    2006-10-10

    Oxidant stress has been shown to play an important role in the pathogenesis of iron deficiency anemia. The aim of this study was to investigate the association between lymphocyte DNA damage, total antioxidant capacity and the degree of anemia in patients with iron deficiency anemia. Twenty-two female with iron deficiency anemia and 22 healthy females were enrolled in the study. Peripheral DNA damage was assessed using alkaline comet assay and plasma total antioxidant capacity was determined using an automated measurement method. Lymphocyte DNA damage of patients with iron deficiency anemia was significantly higher than controls (ptotal antioxidant capacity was significantly lower (ptotal antioxidant capacity and hemoglobin levels (r=0.706, ptotal antioxidant capacity and hemoglobin levels were negatively correlated with DNA damage (r=-0.330, p<0.05 and r=-0.323, p<0.05, respectively). In conclusion, both oxidative stress and DNA damage are increased in IDA patients. Increased oxidative stress seems as an important factor that inducing DNA damage in those IDA patients. The relationships of oxidative stress and DNA damage with the severity of anemia suggest that both oxidative stress and DNA damage may, in part, have a role in the pathogenesis of IDA.

  20. Polyarene mediators for mediated redox flow battery

    Science.gov (United States)

    Delnick, Frank M.; Ingersoll, David; Liang, Chengdu

    2018-01-02

    The fundamental charge storage mechanisms in a number of currently studied high energy redox couples are based on intercalation, conversion, or displacement reactions. With exception to certain metal-air chemistries, most often the active redox materials are stored physically in the electrochemical cell stack thereby lowering the practical gravimetric and volumetric energy density as a tradeoff to achieve reasonable power density. In a general embodiment, a mediated redox flow battery includes a series of secondary organic molecules that form highly reduced anionic radicals as reaction mediator pairs for the reduction and oxidation of primary high capacity redox species ex situ from the electrochemical cell stack. Arenes are reduced to stable anionic radicals that in turn reduce a primary anode to the charged state. The primary anode is then discharged using a second lower potential (more positive) arene. Compatible separators and solvents are also disclosed herein.

  1. The Inhibition Effect of Cell DNA Oxidative Damage and LDL Oxidation by Bovine Colostrums

    Directory of Open Access Journals (Sweden)

    Chih-Wei Chen

    2016-10-01

    Full Text Available In the present study, we investigated the effect of bovine colostrums on inhibition of DNA oxidative damage and low density lipoprotein (LDL oxidation in vitro. Results showed that whey and skimmed milk exhibited not only higher inhibitory activities of oxidative damage of deoxyribose but also an inhibitory effect on the breakdown of supercoiled DNA into open circular DNA and linear DNA. The quantities of 8-OH-2′-dG formed under whey, caseins and skimmed milk treatment were 0.24, 0.24 and 1.24 μg/mL, respectively. The quantity of malondialdehyde formed through LDL oxidation induced by copprous ion was significantly decreased as colostrums protein solutions were added, in which whey and caseins led to a more significant decrease than skimmed milk. The formation of conjugated dienes could be inhibited by treatment with colostrums protein solutions. Whey exhibited the longest lag time of conjugated dienes formation among the colostrums proteins. The lag time of the whey was 2.33 times that of the control. From the results of foregoing, the bovine colostrums protein has potential value in the inhibition of DNA oxidation damage and LDL oxidation.

  2. Aging-associated oxidized albumin promotes cellular senescence and endothelial damage

    Directory of Open Access Journals (Sweden)

    Luna C

    2016-02-01

    Full Text Available Carlos Luna,1,* Matilde Alique,2,* Estefanía Navalmoral,2 Maria-Victoria Noci,3 Lourdes Bohorquez-Magro,2 Julia Carracedo,1 Rafael Ramírez2 1Nephrology Unit, Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC, Reina Sofía University Hospital, Córdoba, Spain; 2Department of Systems Biology, Physiology Unit, Universidad de Alcalá, Madrid, Spain; 3Anesthesia Unit, Reina sofía University Hospital, Córdoba, Spain*These authors contributed equally to this work Abstract: Increased levels of oxidized proteins with aging have been considered a cardiovascular risk factor. However, it is unclear whether oxidized albumin, which is the most abundant serum protein, induces endothelial damage. The results of this study indicated that with aging processes, the levels of oxidized proteins as well as endothelial microparticles release increased, a novel marker of endothelial damage. Among these, oxidized albumin seems to play a principal role. Through in vitro studies, endothelial cells cultured with oxidized albumin exhibited an increment of endothelial damage markers such as adhesion molecules and apoptosis levels. In addition, albumin oxidation increased the amount of endothelial microparticles that were released. Moreover, endothelial cells with increased oxidative stress undergo senescence. In addition, endothelial cells cultured with oxidized albumin shown a reduction in endothelial cell migration measured by wound healing. As a result, we provide the first evidence that oxidized albumin induces endothelial injury which then contributes to the increase of cardiovascular disease in the elderly subjects.Keywords: elderly, oxidative stress, microparticles, vascular damage

  3. Prevention of short-term ultraviolet B radiation-mediated damages by resveratrol in SKH-1 hairless mice

    International Nuclear Information System (INIS)

    Afaq, Farrukh; Adhami, Vaqar Mustafa; Ahmad, Nihal

    2003-01-01

    Nonmelanoma skin cancer is the most common cancer among humans and solar UV radiation, particularly its UVB component (290-320 nm), is its major cause. One way to reduce the occurrence of the cancer is via the use of substances (often antioxidants) termed 'photochemopreventive agents'. Resveratrol (trans-3,4',5-trihydroxystilbene), a phytoalexin found in grapes, nuts, fruits, and red wine, is a potent antioxidant with strong anti-inflammatory and antiproliferative properties. This study was designed to examine whether resveratrol possesses the potential to ameliorate the damages caused by short-term UVB exposure to mouse skin. Single topical application of resveratrol (25 μmol/0.2 ml acetone per mouse) to SKH-1 hairless mice was found to result in significant inhibition of UVB (180 mJ/cm 2 )-mediated increase in bifold skin thickness and skin edema. The resveratrol treatment to mouse skin was also found to result in significant inhibition of UVB-mediated induction of cyclooxygenase and ornithine decarboxylase (ODC) enzyme activities and protein expression of ODC, which are well-established markers for tumor promotion. We also observed that resveratrol inhibits UVB-mediated increased level of lipid peroxidation, a marker of oxidative stress. Taken together, our results suggest that resveratrol may afford substantial protection against the damages caused by UVB exposure, and these protective effects may be mediated via its antioxidant properties

  4. Mechanism of melatonin protection against copper-ascorbate-induced oxidative damage in vitro through isothermal titration calorimetry.

    Science.gov (United States)

    Ghosh, Arnab K; Naaz, Shamreen; Bhattacharjee, Bharati; Ghosal, Nirajan; Chattopadhyay, Aindrila; Roy, Souvik; Reiter, Russel J; Bandyopadhyay, Debasish

    2017-07-01

    Involvement of oxidative stress in cardiovascular diseases is well established. Melatonin's role as an antioxidant and free radical scavenger via its receptor dependent and receptor independent pathways is well known. The aim of this study is to identify and elaborate upon a third mechanism by which melatonin is able to abrogate oxidative stress. Oxidative stress was induced in vitro, by copper (0.2mM)-ascorbate (1mM) in isolated goat heart mitochondria, cytosol and peroxisomes and they were co-incubated with graded doses of melatonin. Similar experiments in a cell-free chemical system involving two pure antioxidant enzymes, Cu-Zn superoxide dismutase and catalase was also carried out. Biochemical changes in activity of these antioxidant enzymes were analysed. Isothermal titration calorimetric studies with pure Cu-Zn superoxide dismutase and catalase were also carried out. Incubation with copper-ascorbate led to alteration in activity of Cu-Zn superoxide dismutase and catalase which were found to be protected upon co-incubation with melatonin (80μM for catalase and 1μM for others). Results of isothermal titration calorimetric studies with pure Cu-Zn superoxide dismutase and catalase along with different combinations of copper chloride, ascorbic acid and melatonin suggest that when melatonin is present in the reaction medium along with copper-ascorbate, it restrains the copper-ascorbate molecules by binding with them physically along with scavenging the free radicals generated by them. The present study suggests that possibly, binding of melatonin with antioxidant enzymes masks the vulnerable sites of these antioxidant enzymes, thus preventing oxidative damage by copper-ascorbate molecules. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Resveratrol attenuates radiation damage in Caenorhabditis elegans by preventing oxidative stress

    International Nuclear Information System (INIS)

    Ye Kan; Gu Guixiong; Ji Chenbo; Ni Yuhui; Chen Xiaohui; Guo Xirong; Lu Xiaowei; Gao Chunlin; Zhao Yaping

    2010-01-01

    Resveratrol, a member of a class of polyphenolic compounds known as flavonols, has been extensively studied for its anticancer, antiviral, anti-inflammatory, and neuroprotective roles. Caenorhabidits elegans is a well-established animal for investigating responses to radiation. We found that resveratrol may provide protection against hazardous radiation. Pre-treatment with resveratrol extended both the maximum and mean life span of irradiated C. elegans. Resveratrol acted as a strong radical scavenger and regulated superoxide dismutase (SOD) expression. In addition, resveratrol was shown to be capable of alleviating γ-ray radiation exposure-induced reduction in mitochondrial SOD expression. Ultimately, a correlation may exist between dietary intake of trace amounts of resveratrol and anti-aging effects. A specific response mechanism may be activated after the administration of resveratrol in irradiated animals. Our results suggest the protective effect of resveratrol is due to its strong ability to protect from oxidative stress and protective effects in mitochondria. Therefore, resveratrol is potentially an effective protecting agent against irradiative damage. (author)

  6. Oxidative DNA damage during sleep periods among nightshift workers.

    Science.gov (United States)

    Bhatti, Parveen; Mirick, Dana K; Randolph, Timothy W; Gong, Jicheng; Buchanan, Diana Taibi; Zhang, Junfeng Jim; Davis, Scott

    2016-08-01

    Oxidative DNA damage may be increased among nightshift workers because of suppression of melatonin, a cellular antioxidant, and/or inflammation related to sleep disruption. However, oxidative DNA damage has received limited attention in previous studies of nightshift work. From two previous cross-sectional studies, urine samples collected during a night sleep period for 217 dayshift workers and during day and night sleep (on their first day off) periods for 223 nightshift workers were assayed for 8-hydroxydeoxyguanosine (8-OH-dG), a marker of oxidative DNA damage, using high-performance liquid chromatography with electrochemical detection. Urinary measures of 6-sulfatoxymelatonin (aMT6s), a marker of circulating melatonin levels, and actigraphy-based sleep quality data were also available. Nightshift workers during their day sleep periods excreted 83% (p=0.2) and 77% (p=0.03) of the 8-OH-dG that dayshift workers and they themselves, respectively, excreted during their night sleep periods. Among nightshift workers, higher aMT6s levels were associated with higher urinary 8-OH-dG levels, and an inverse U-shaped trend was observed between 8-OH-dG levels and sleep efficiency and sleep duration. Reduced excretion of 8-OH-dG among nightshift workers during day sleep may reflect reduced functioning of DNA repair machinery, which could potentially lead to increased cellular levels of oxidative DNA damage. Melatonin disruption among nightshift workers may be responsible for the observed effect, as melatonin is known to enhance repair of oxidative DNA damage. Quality of sleep may similarly impact DNA repair. Cellular levels of DNA damage will need to be evaluated in future studies to help interpret these findings. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  7. Intramolecular transformation of thiyl radicals to α-aminoalkyl radicals: 'ab initio' calculations on homocystein

    International Nuclear Information System (INIS)

    Chhun, S.; Berges, J.; Bleton, V.; Abedinzadeh, Z.

    2000-01-01

    One-electron oxidation of thiols by oxidizing radicals leads to the formation of thiyl radical and carbon-centered radicals. It has been shown experimentally that in the absence of oxygen, the thiyl radicals derived from certain thiols of biological interest such as glutathion, cysteine and homocysteine decay rapidly by intramolecular rearrangement reactions into the carbon-centered radical. In the present work we have investigated theoretically the structure and the stability of thiyl and carbon-centered radicals of homocysteine in order to check the possibility of this rearrangement. (author)

  8. Molecular Mechanisms behind Free Radical Scavengers Function against Oxidative Stress

    Directory of Open Access Journals (Sweden)

    Fereshteh Ahmadinejad

    2017-07-01

    Full Text Available Accumulating evidence shows that oxidative stress is involved in a wide variety of human diseases: rheumatoid arthritis, Alzheimer’s disease, Parkinson’s disease, cancers, etc. Here, we discuss the significance of oxidative conditions in different disease, with the focus on neurodegenerative disease including Parkinson’s disease, which is mainly caused by oxidative stress. Reactive oxygen and nitrogen species (ROS and RNS, respectively, collectively known as RONS, are produced by cellular enzymes such as myeloperoxidase, NADPH-oxidase (nicotinamide adenine dinucleotide phosphate-oxidase and nitric oxide synthase (NOS. Natural antioxidant systems are categorized into enzymatic and non-enzymatic antioxidant groups. The former includes a number of enzymes such as catalase and glutathione peroxidase, while the latter contains a number of antioxidants acquired from dietary sources including vitamin C, carotenoids, flavonoids and polyphenols. There are also scavengers used for therapeutic purposes, such as 3,4-dihydroxyphenylalanine (L-DOPA used routinely in the treatment of Parkinson’s disease (not as a free radical scavenger, and 3-methyl-1-phenyl-2-pyrazolin-5-one (Edaravone that acts as a free radical detoxifier frequently used in acute ischemic stroke. The cell surviving properties of L-DOPA and Edaravone against oxidative stress conditions rely on the alteration of a number of stress proteins such as Annexin A1, Peroxiredoxin-6 and PARK7/DJ-1 (Parkinson disease protein 7, also known as Protein deglycase DJ-1. Although they share the targets in reversing the cytotoxic effects of H2O2, they seem to have distinct mechanism of function. Exposure to L-DOPA may result in hypoxia condition and further induction of ORP150 (150-kDa oxygen-regulated protein with its concomitant cytoprotective effects but Edaravone seems to protect cells via direct induction of Peroxiredoxin-2 and inhibition of apoptosis.

  9. Nitrate radicals and biogenic volatile organic compounds: oxidation, mechanisms, and organic aerosol

    Science.gov (United States)

    Oxidation of biogenic volatile organic compounds (BVOC) by the nitrate radical (NO3) represents one of the important interactions between anthropogenic emissions related to combustion and natural emissions from the biosphere. This interaction has been recognized for more than 3 d...

  10. Singlet oxygen-mediated protein oxidation

    DEFF Research Database (Denmark)

    Wright, Adam; Bubb, William A; Hawkins, Clare Louise

    2002-01-01

    Singlet oxygen (1O2) is generated by a number of enzymes as well as by UV or visible light in the presence of a sensitizer and has been proposed as a damaging agent in a number of pathologies including cataract, sunburn, and skin cancers. Proteins, and Cys, Met, Trp, Tyr and His side chains...... in particular, are major targets for 1O2 as a result of their abundance and high rate constants for reaction. In this study it is shown that long-lived peroxides are formed on free Tyr, Tyr residues in peptides and proteins, and model compounds on exposure to 1O2 generated by both photochemical and chemical....... These studies demonstrate that long-lived Tyr-derived peroxides are formed on proteins exposed to 1O2 and that these may promote damage to other targets via further radical generation....

  11. New insights into the aquatic photochemistry of fluoroquinolone antibiotics: Direct photodegradation, hydroxyl-radical oxidation, and antibacterial activity changes

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Linke; Na, Guangshui [Key Laboratory for Ecological Environment in Coastal Areas (SOA), National Marine Environmental Monitoring Center, Dalian 116023 (China); Zhang, Siyu [Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016 (China); Li, Kai [Key Laboratory for Ecological Environment in Coastal Areas (SOA), National Marine Environmental Monitoring Center, Dalian 116023 (China); Zhang, Peng, E-mail: pzhang@nmemc.org.cn [Key Laboratory for Ecological Environment in Coastal Areas (SOA), National Marine Environmental Monitoring Center, Dalian 116023 (China); Ren, Honglei; Yao, Ziwei [Key Laboratory for Ecological Environment in Coastal Areas (SOA), National Marine Environmental Monitoring Center, Dalian 116023 (China)

    2015-09-15

    The ubiquity and photoreactivity of fluoroquinolone antibiotics (FQs) in surface waters urge new insights into their aqueous photochemical behavior. This study concerns the photochemistry of 6 FQs: ciprofloxacin, danofloxacin, levofloxacin, sarafloxacin, difloxacin and enrofloxacin. Methods were developed to calculate their solar direct photodegradation half-lives (t{sub d,E}) and hydroxyl-radical oxidation half-lives (t{sub ·OH,E}) in sunlit surface waters. The t{sub d,E} values range from 0.56 min to 28.8 min at 45° N latitude, whereas t{sub ·OH,E} ranges from 3.24 h to 33.6 h, suggesting that most FQs tend to undergo fast direct photolysis rather than hydroxyl-radical oxidation in surface waters. However, a case study for levofloxacin and sarafloxacin indicated that the hydroxyl-radical oxidation induced risky photochlorination and resulted in multi-degradation pathways, such as piperazinyl hydroxylation and clearage. Changes in the antibacterial activity of FQs caused by photodegradation in various waters were further examined using Escherichia coli, and it was found that the activity evolution depended on primary photodegradation pathways and products. Primary intermediates with intact FQ nuclei retained significant antibacterial activity. These results are important for assessing the fate and risk of FQs in surface waters. - Highlights: • It is first reported on hydroxyl-radical oxidation of 6 fluoroquinolone antibiotics. • Methods were developed to assess photolysis and oxidation fate in surface waters. • The neutral form reacted faster with hydroxyl radical than protonated forms. • The main oxidation intermediates and transformation pathways were clarified. • The antibacterial activity changes depend on dominant photolysis pathways.

  12. Placental oxidative stress and maternal endothelial function in pregnant women with normotensive fetal growth restriction.

    Science.gov (United States)

    Yoshida, Atsumi; Watanabe, Kazushi; Iwasaki, Ai; Kimura, Chiharu; Matsushita, Hiroshi; Wakatsuki, Akihiko

    2018-04-01

    The purpose of this study was to investigate the relationship between placental oxidative stress and maternal endothelial function in pregnant women with normotensive fetal growth restriction (FGR). We examined serum concentrations of oxygen free radicals (d-ROMs), maternal angiogenic factor (PlGF), and sFlt-1, placental oxidative DNA damage, and maternal endothelial function in 17 women with early-onset preeclampsia (PE), 18 with late-onset PE, 14 with normotensive FGR, and 21 controls. Flow-mediated vasodilation (FMD) was assessed as a marker of maternal endothelial function. Immunohistochemical analysis was performed to measure the proportion of placental trophoblast cell nuclei staining positive for 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage. Maternal serum d-ROM, sFlt-1 concentrations, and FMD did not significantly differ between the control and normotensive FGR groups. The proportion of nuclei staining positive for 8-OHdG was significantly higher in the normotensive FGR group relative to the control group. Our findings demonstrate that, despite the presence of placental oxidative DNA damage as observed in PE patients, pregnant women with normotensive FGR show no increase in the concentrations of sFlt-1 and d-ROMs, or a decrease in FMD.

  13. Changes in free-radical scavenging ability of kombucha tea during fermentation.

    Science.gov (United States)

    Jayabalan, R; Subathradevi, P; Marimuthu, S; Sathishkumar, M; Swaminathan, K

    2008-07-01

    Kombucha tea is a fermented tea beverage produced by fermenting sugared black tea with tea fungus (kombucha). Free-radical scavenging abilities of kombucha tea prepared from green tea (GTK), black tea (BTK) and tea waste material (TWK) along with pH, phenolic compounds and reducing power were investigated during fermentation period. Phenolic compounds, scavenging activity on DPPH radical, superoxide radical (xanthine-xanthine oxidase system) and inhibitory activity against hydroxyl radical mediated linoleic acid oxidation (ammonium thiocyanate assay) were increased during fermentation period, whereas pH, reducing power, hydroxyl radical scavenging ability (ascorbic acid-iron EDTA) and anti-lipid peroxidation ability (thiobarbituric assay) were decreased. From the present study, it is obvious that there might be some chances of structural modification of components in tea due to enzymes liberated by bacteria and yeast during kombucha fermentation which results in better scavenging performance on nitrogen and superoxide radicals, and poor scavenging performance on hydroxyl radicals. Copyright © 2007 Elsevier Ltd. All rights reserved.

  14. Oxidative burst of circulating neutrophils following traumatic brain injury in human.

    Directory of Open Access Journals (Sweden)

    Yiliu Liao

    Full Text Available Besides secondary injury at the lesional site, Traumatic brain injury (TBI can cause a systemic inflammatory response, which may cause damage to initially unaffected organs and potentially further exacerbate the original injury. Here we investigated plasma levels of important inflammatory mediators, oxidative activity of circulating leukocytes, particularly focusing on neutrophils, from TBI subjects and control subjects with general trauma from 6 hours to 2 weeks following injury, comparing with values from uninjured subjects. We observed increased plasma level of inflammatory cytokines/molecules TNF-α, IL-6 and CRP, dramatically increased circulating leukocyte counts and elevated expression of TNF-α and iNOS in circulating leukocytes from TBI patients, which suggests a systemic inflammatory response following TBI. Our data further showed increased free radical production in leukocyte homogenates and elevated expression of key oxidative enzymes iNOS, COX-2 and NADPH oxidase (gp91(phox in circulating leukocytes, indicating an intense induction of oxidative burst following TBI, which is significantly greater than that in control subjects with general trauma. Furthermore, flow cytometry assay proved neutrophils as the largest population in circulation after TBI and showed significantly up-regulated oxidative activity and suppressed phagocytosis rate for circulating neutrophils following brain trauma. It suggests that the highly activated neutrophils might play an important role in the secondary damage, even outside the injured brain. Taken together, the potent systemic inflammatory response induced by TBI, especially the intensively increase oxidative activity of circulating leukocytes, mainly neutrophils, may lead to a systemic damage, dysfunction/damage of bystander tissues/organs and even further exacerbate secondary local damage. Controlling these pathophysiological processes may be a promising therapeutic strategy and will protect unaffected

  15. Free radical inactivation of trypsin

    International Nuclear Information System (INIS)

    Cudina, Ivana; Jovanovic, S.V.

    1988-01-01

    Reactivities of free radical oxidants, radical OH, Br2-anion radical and Cl 3 COO radical and a reductant, CO2-anion radical, with trypsin and reactive protein components were determined by pulse radiolysis of aqueous solutions at pH 7, 20 0 C. Highly reactive free radicals, radical OH, Br2-anion radical and CO2-anion radical, react with trypsin at diffusion controlled rates. Moderately reactive trichloroperoxy radical, k(Cl 3 COO radical + trypsin) preferentially oxidizes histidine residues. The efficiency of inactivation of trypsin by free radicals is inversely proportional to their reactivity. The yields of inactivation of trypsin by radical OH, Br2-anion radical and CO2-anion radical are low, G(inactivation) = 0.6-0.8, which corresponds to ∼ 10% of the initially produced radicals. In contrast, Cl 3 COO radical inactivates trypsin with ∼ 50% efficiency, i.e. G(inactivation) = 3.2. (author)

  16. Effects of cryotherapy combined with therapeutic ultrasound on oxidative stress and tissue damage after musculoskeletal contusion in rats.

    Science.gov (United States)

    Martins, C N; Moraes, M B; Hauck, M; Guerreiro, L F; Rossato, D D; Varela, A S; da Rosa, C E; Signori, L U

    2016-12-01

    To investigate the combined effects of cryotherapy and pulsed ultrasound therapy (PUT) on oxidative stress parameters, tissue damage markers and systemic inflammation after musculoskeletal injury. Experimental animal study. Research laboratory. Seventy male Wistar rats were divided into five groups: control, lesion, cryotherapy, PUT, and cryotherapy+PUT. The gastrocnemius muscle was injured by mechanical crushing. Cryotherapy was applied immediately after injury (immersion in water at 10°C for 20minutes). PUT was commenced 24hours after injury (1MHz, 0.4W/cm 2SPTA , 20% duty cycle, 5minutes). All animals were treated every 8hours for 3 days. Oxidative stress in muscle was evaluated by concentration of reactive oxygen species (ROS), lipid peroxidation (LPO), anti-oxidant capacity against peroxyl radicals (ACAP) and catalase. Plasma levels of creatine kinase (CK), lactate dehydrogenase (LDH) and C-reactive protein (CRP) were assessed. When applied individually, cryotherapy and PUT reduced CK, LDH, CRP and LPO caused by muscle damage. Cryotherapy+PUT in combination maintained the previous results, caused a reduction in ROS [P=0.005, mean difference -0.9×10 -8 relative area, 95% confidence interval (CI) -0.2 to -1.9], and increased ACAP {P=0.007, mean difference 0.34 1/[relative area with/without 2,2-azobis(2-methylpropionamidine)dihydrochloride], 95% CI 0.07 to 0.61} and catalase (P=0.002, mean difference 0.41units/mg protein, 95% CI 0.09 to 0.73) compared with the lesion group. Cryotherapy+PUT in combination reduced oxidative stress in muscle, contributing to a reduction in adjacent damage and tissue repair. Copyright © 2016 Chartered Society of Physiotherapy. Published by Elsevier Ltd. All rights reserved.

  17. Oxidatively generated DNA/RNA damage in psychological stress states

    DEFF Research Database (Denmark)

    Jørgensen, Anders

    2013-01-01

    age-related somatic disorders. The overall aim of the PhD project was to investigate the relation between psychopathology, psychological stress, stress hormone secretion and oxidatively generated DNA and RNA damage, as measured by the urinary excretion of markers of whole-body DNA/RNA oxidation (8...... between the 24 h urinary cortisol excretion and the excretion of 8-oxodG/8-oxoGuo, determined in the same samples. Collectively, the studies could not confirm an association between psychological stress and oxidative stress on nucleic acids. Systemic oxidatively generated DNA/RNA damage was increased......Both non-pathological psychological stress states and mental disorders are associated with molecular, cellular and epidemiological signs of accelerated aging. Oxidative stress on nucleic acids is a critical component of cellular and organismal aging, and a suggested pathogenic mechanism in several...

  18. Oxidative stress can alter the antigenicity of immunodominant peptides

    DEFF Research Database (Denmark)

    Weiskopf, Daniela; Schwanninger, Angelika; Weinberger, Birgit

    2010-01-01

    APCs operate frequently under oxidative stress induced by aging, tissue damage, pathogens, or inflammatory responses. Phagocytic cells produce peroxides and free-radical species that facilitate pathogen clearance and can in the case of APCs, also lead to oxidative modifications of antigenic prote...

  19. Secoisolariciresinol diglucoside abrogates oxidative stress-induced damage in cardiac iron overload condition.

    Directory of Open Access Journals (Sweden)

    Stephanie Puukila

    Full Text Available Cardiac iron overload is directly associated with cardiac dysfunction and can ultimately lead to heart failure. This study examined the effect of secoisolariciresinol diglucoside (SDG, a component of flaxseed, on iron overload induced cardiac damage by evaluating oxidative stress, inflammation and apoptosis in H9c2 cardiomyocytes. Cells were incubated with 50 μ5M iron for 24 hours and/or a 24 hour pre-treatment of 500 μ M SDG. Cardiac iron overload resulted in increased oxidative stress and gene expression of the inflammatory mediators tumor necrosis factor-α, interleukin-10 and interferon γ, as well as matrix metalloproteinases-2 and -9. Increased apoptosis was evident by increased active caspase 3/7 activity and increased protein expression of Forkhead box O3a, caspase 3 and Bax. Cardiac iron overload also resulted in increased protein expression of p70S6 Kinase 1 and decreased expression of AMP-activated protein kinase. Pre-treatment with SDG abrogated the iron-induced increases in oxidative stress, inflammation and apoptosis, as well as the increased p70S6 Kinase 1 and decreased AMP-activated protein kinase expression. The decrease in superoxide dismutase activity by iron treatment was prevented by pre-treatment with SDG in the presence of iron. Based on these findings we conclude that SDG was cytoprotective in an in vitro model of iron overload induced redox-inflammatory damage, suggesting a novel potential role for SDG in cardiac iron overload.

  20. Oxidative damage of DNA in subjects occupationally exposed to lead.

    Science.gov (United States)

    Pawlas, Natalia; Olewińska, Elżbieta; Markiewicz-Górka, Iwona; Kozłowska, Agnieszka; Januszewska, Lidia; Lundh, Thomas; Januszewska, Ewa; Pawlas, Krystyna

    2017-09-01

    Exposure to lead (Pb) in environmental and occupational settings continues to be a serious public health problem and may pose an elevated risk of genetic damage. The aim of this study was to assess the level of oxidative stress and DNA damage in subjects occupationally exposed to lead. We studied a population of 78 male workers exposed to lead in a lead and zinc smelter and battery recycling plant and 38 men from a control group. Blood lead levels were detected by graphite furnace atomic absorption spectrophotometry and plasma lead levels by inductively coupled plasma-mass spectrometry. The following assays were performed to assess the DNA damage and oxidative stress: comet assay, determination of 8-hydroxy-2'-deoxyguanosine (8-OHdG), lipid peroxidation and total antioxidant status (TAS). The mean concentration of lead in the blood of the exposed group was 392 ± 103 μg/L and was significantly higher than in the control group (30.3 ± 29.4 μg/L, p lead exposure [lead in blood, lead in plasma, zinc protoporphyrin (ZPP)] and urine concentration of 8-OHdG. The level of oxidative damage of DNA was positively correlated with the level of lipid peroxidation (TBARS) and negatively with total anti-oxidative status (TAS). Our study suggests that occupational exposure causes an increase in oxidative damage to DNA, even in subjects with relatively short length of service (average length of about 10 years). 8-OHdG concentration in the urine proved to be a sensitive and non-invasive marker of lead induced genotoxic damage.

  1. EGFR mediates astragaloside IV-induced Nrf2 activation to protect cortical neurons against in vitro ischemia/reperfusion damages

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Da-min [Department of Anesthesiology, Affiliated Yixing People' s Hospital, Jiangsu University, Yixing (China); Lu, Pei-Hua, E-mail: lphty1_1@163.com [Department of Medical Oncology, Wuxi People' s Hospital Affiliated to Nanjing Medical University, Wuxi (China); Zhang, Ke; Wang, Xiang [Department of Anesthesiology, Affiliated Yixing People' s Hospital, Jiangsu University, Yixing (China); Sun, Min [Department of General Surgery, Affiliated Yixing People' s Hospital, Jiangsu University, Yixing (China); Chen, Guo-Qian [Department of Clinical Laboratory, Wuxi People' s Hospital Affiliated to Nanjing Medical University, Wuxi (China); Wang, Qiong, E-mail: WangQiongprof1@126.com [Department of Clinical Laboratory, Wuxi People' s Hospital Affiliated to Nanjing Medical University, Wuxi (China)

    2015-02-13

    In this study, we tested the potential role of astragaloside IV (AS-IV) against oxygen and glucose deprivation/re-oxygenation (OGD/R)-induced damages in murine cortical neurons, and studied the associated signaling mechanisms. AS-IV exerted significant neuroprotective effects against OGD/R by reducing reactive oxygen species (ROS) accumulation, thereby attenuating oxidative stress and neuronal cell death. We found that AS-IV treatment in cortical neurons resulted in NF-E2-related factor 2 (Nrf2) signaling activation, evidenced by Nrf2 Ser-40 phosphorylation, and its nuclear localization, as well as transcription of antioxidant-responsive element (ARE)-regulated genes: heme oxygenase-1 (HO-1), NAD(P)H:quinone oxidoreductase 1 (NQO-1) and sulphiredoxin 1 (SRXN-1). Knockdown of Nrf2 through lentiviral shRNAs prevented AS-IV-induced ARE genes transcription, and abolished its anti-oxidant and neuroprotective activities. Further, we discovered that AS-IV stimulated heparin-binding-epidermal growth factor (HB-EGF) release to trans-activate epidermal growth factor receptor (EGFR) in cortical neurons. Blockage or silencing EGFR prevented Nrf2 activation by AS-IV, thus inhibiting AS-IV-mediated anti-oxidant and neuroprotective activities against OGD/R. In summary, AS-IV protects cortical neurons against OGD/R damages through activating of EGFR-Nrf2 signaling. - Highlights: • Pre-treatment of astragaloside IV (AS-IV) protects murine cortical neurons from OGD/R. • AS-IV activates Nrf2-ARE signaling in murine cortical neurons. • Nrf2 is required for AS-IV-mediated anti-oxidant and neuroprotective activities. • AS-IV stimulates HB-EGF release to trans-activate EGFR in murine cortical neurons. • EGFR mediates AS-IV-induced Nrf2 activation and neuroprotection against OGD/R.

  2. EGFR mediates astragaloside IV-induced Nrf2 activation to protect cortical neurons against in vitro ischemia/reperfusion damages

    International Nuclear Information System (INIS)

    Gu, Da-min; Lu, Pei-Hua; Zhang, Ke; Wang, Xiang; Sun, Min; Chen, Guo-Qian; Wang, Qiong

    2015-01-01

    In this study, we tested the potential role of astragaloside IV (AS-IV) against oxygen and glucose deprivation/re-oxygenation (OGD/R)-induced damages in murine cortical neurons, and studied the associated signaling mechanisms. AS-IV exerted significant neuroprotective effects against OGD/R by reducing reactive oxygen species (ROS) accumulation, thereby attenuating oxidative stress and neuronal cell death. We found that AS-IV treatment in cortical neurons resulted in NF-E2-related factor 2 (Nrf2) signaling activation, evidenced by Nrf2 Ser-40 phosphorylation, and its nuclear localization, as well as transcription of antioxidant-responsive element (ARE)-regulated genes: heme oxygenase-1 (HO-1), NAD(P)H:quinone oxidoreductase 1 (NQO-1) and sulphiredoxin 1 (SRXN-1). Knockdown of Nrf2 through lentiviral shRNAs prevented AS-IV-induced ARE genes transcription, and abolished its anti-oxidant and neuroprotective activities. Further, we discovered that AS-IV stimulated heparin-binding-epidermal growth factor (HB-EGF) release to trans-activate epidermal growth factor receptor (EGFR) in cortical neurons. Blockage or silencing EGFR prevented Nrf2 activation by AS-IV, thus inhibiting AS-IV-mediated anti-oxidant and neuroprotective activities against OGD/R. In summary, AS-IV protects cortical neurons against OGD/R damages through activating of EGFR-Nrf2 signaling. - Highlights: • Pre-treatment of astragaloside IV (AS-IV) protects murine cortical neurons from OGD/R. • AS-IV activates Nrf2-ARE signaling in murine cortical neurons. • Nrf2 is required for AS-IV-mediated anti-oxidant and neuroprotective activities. • AS-IV stimulates HB-EGF release to trans-activate EGFR in murine cortical neurons. • EGFR mediates AS-IV-induced Nrf2 activation and neuroprotection against OGD/R

  3. Accumulation of Oxidized Low-Density Lipoprotein in Psoriatic Skin and Changes of Plasma Lipid Levels in Psoriatic Patients

    Directory of Open Access Journals (Sweden)

    Nilgun Solak Tekin

    2007-01-01

    Full Text Available Background. Psoriasis is a chronic inflammatory skin disease characterized by an accelerated turnover of epidermal cells and an incomplete differentiation in epidermis with lesion. However, the exact etiology of psoriasis is unknown. Abnormalities in essential fatty acid metabolism, free radical generation, lipid peroxidation, and release of lymphokines have been proposed. Objective. Our purpose was to evaluate the plasma lipids and oxidized low-density lipoprotein accumulation in psoriatic skin lesion in order to ascertain the possible participation of oxidative stress and oxidative modification of lipids in pathogenesis of psoriasis. Methods. The study group included 84 patients with psoriasis, and 40 sex- and age-matched healthy volunteers. Blood lipid profile was determined. Psoriatic and nonlesional skin samples of psoriatic patients were evaluated for the presence of oxidized low-density lipoprotein by using an immune-fluorescent staining method. Results. The mean levels of lipids (total cholesterol, triglyceride, and LDL cholesterol in patients with psoriasis were found to be significantly higher than those of healthy subjects. Psoriatic skins were shown positive oxidized low-density lipoprotein staining. There was no staining in nonlesional skin samples of the same individuals. Conclusion. Lipid peroxidation mediated by free radicals is believed to be one of the important causes of cell membrane destruction and cell damage. This study shows for the first time the accumulation of oxidized low-density lipoprotein in psoriatic skin lesion. We believe that accumulation of ox-LDL in psoriatic skin may have an important role in the immune-inflammatory events that result in progressive skin damage.

  4. Radical's view of sciences

    International Nuclear Information System (INIS)

    Mittal, J.P.

    2004-01-01

    Full text: General concept in radiation biology is that free radicals are highly reactive and they can damage vital cellular molecules leading to injurious effects. However, in this talk, evidence will be presented through the techniques of electron paramagnetic resonance ( EPR ) and pulse radiolysis that free radicals can be highly selective in their reaction with the target molecules. In addition, attempts will be made to present a brief account of emerging scenario of free radical generation, identification and their involvement in radiation damage mechanisms in chemical and biological systems

  5. Effect of metal complexation to anti-inflammatory over the action against oxidative and free radicals: ketoprofen action; Efeito da complexacao de metais aos antiinflamatorios na acao contra agentes oxidativos e radicais livres: acao do cetoprofeno

    Energy Technology Data Exchange (ETDEWEB)

    Manente, Francine Alessandra; Mello, Lucas Rosolen de Almeida; Vellosa, Jose Carlos Rebuglio [UEPG, Universidade Estadual de Ponta Grossa, Departamento de Analises Clinicas eToxicologicas, Ponta Grossa, PR (Brazil); Khalil, Omar Arafat Kdudsi [IFG, Instituto Federal de Goias, Campus de Formosa, Formosa - GO (Brazil); Carvalho, Claudio Teodoro de [UFGD, Universidade Federal da Grande Dourados, Faculdade de Ciencias Exatas e Tecnologias, Dourados-MS (Brazil); Bannach, Gilbert [UNESP, Universidade Estadual Paulista Julio de Mesquita Filho, Faculdade de Ciencias de Bauru, Bauru, SP (Brazil)

    2011-07-01

    Free radicals are highly reactive species generated in living organisms for the purpose of protection. However, in some circumstances, they are responsible for the occurrence or aggravation of tissue damage. Many anti-inflammatory drugs have a direct effect on free radicals and not radical reactive species, which contributes to its actions against inflammation. Ketoprofen is a nonsteroidal anti-inflammatory agent that generates free radicals by photo irradiation and has an important hemolytic effect with that. The complexation of metals to different drugs has been used as a strategy to improve the pharmacological action of different molecules and reduce their side effects. This paper presents the results of ketoprofen and their metallic complexes action on erythrocytes and free radicals. It was observed that the cerium enhances the scavenger properties of ketoprofen on free radicals, while copper enhances its action over non-radical oxidants. Copper also reduced the hemolytic effect presented by ketoprofen meanwhile its cerium derivative maintained it. (author)

  6. Oxidative stress damage as a detrimental factor in preterm birth pathology

    Directory of Open Access Journals (Sweden)

    Ramkumar eMenon

    2014-11-01

    Full Text Available Normal term and spontaneous preterm births (PTB are documented to be associated with oxidative stress (OS, and imbalances in the redox system (balance between pro- and antioxidant have been reported in the maternal-fetal intrauterine compartments. The exact mechanism of labor initiation either at term or preterm by OS is still unclear, and this lack of understanding can partially be blamed for failure of antioxidant supplementation trials in PTB prevention. Based on recent findings from our laboratory, we postulate heterogeneity in host OS response. The physiologic (at term and pathophysiologic (preterm pathways of labor are not mediated by OS alone but by OS-induced damage to intrauterine tissues, especially fetal membranes of the placenta. OS damage affects all major cellular elements in the fetal cells, and this damage promotes fetal cell senescence (aging. The aging of the fetal cells are predominated by p38 mitogen activated kinase (p38MAPK pathways. Senescing cells generate biomolecular signals that are uterotonic, triggering labor process. The aging of fetal cells is normal at term. However, aging is premature in PTB, especially in those PTBs complicated by preterm premature rupture of the membranes (pPROM, where elements of redox imbalances and OS damage are more dominant. We postulate that fetal cell senescence signals generated by OS damage are likely triggers for labor. This review highlights the mechanisms involved in senescence development at term and preterm by OS damage and provides insight into novel fetal signals of labor initiation pathways.

  7. Ganoderma extract prevents albumin-induced oxidative damage and chemokines synthesis in cultured human proximal tubular epithelial cells.

    Science.gov (United States)

    Lai, Kar Neng; Chan, Loretta Y Y; Tang, Sydney C W; Leung, Joseph C K

    2006-05-01

    Ganoderma lucidum (Ganoderma or lingzhi) is widely used as an alternative medicine remedy to promote health and longevity. Recent studies have indicated that components extracted from Ganoderma have a wide range of pharmacological actions including suppressing inflammation and scavenging free radicals. We recently reported that tubular secretion of interleukin-8 (IL-8) induced by albumin is important in the pathogenesis of tubulointerstitial injury in the proteinuric state. In this study, we explored the protective effect of Ganoderma extract (LZ) on albumin-induced kidney epithelial injury. Growth arrested human proximal tubular epithelial cells (PTECs) were incubated with 0.625 to 10 mg/ml human serum albumin (HSA) for up to 72 h. HSA induced DNA damage and apoptosis in PTEC in a dose- and time-dependent manner. Co-incubation of PTEC with 4-64 microg/ml LZ significantly reduced the oxidative damage and cytotoxic effect of HSA in a dose-dependent manner (PGanoderma (16 microg/ml). To explore the components of LZ that exhibited most protective effect in HSA-induced PTEC damages, LZ was further separated into two sub-fractions, LZF1 (MW effective in reducing sICAM-1 released from HSA-activated PTEC whereas the high molecular weight LZ (unfractionated LZ) was more effective in diminishing IL-8 production. Our results suggest that Ganoderma significantly reduces oxidative damages and apoptosis in PTEC induced by HSA. The differential reduction of IL-8 or sICAM-1 released from HSA-activated PTEC by different components of the LZ implicates that components of Ganoderma with different molecular weights could play different roles and operate different mechanisms in preventing HSA-induced PTEC damage.

  8. Lipids and Oxidative Stress Associated with Ethanol-Induced Neurological Damage

    Directory of Open Access Journals (Sweden)

    José A. Hernández

    2016-01-01

    Full Text Available The excessive intake of alcohol is a serious public health problem, especially given the severe damage provoked by chronic or prenatal exposure to alcohol that affects many physiological processes, such as memory, motor function, and cognitive abilities. This damage is related to the ethanol oxidation in the brain. The metabolism of ethanol to acetaldehyde and then to acetate is associated with the production of reactive oxygen species that accentuate the oxidative state of cells. This metabolism of ethanol can induce the oxidation of the fatty acids in phospholipids, and the bioactive aldehydes produced are known to be associated with neurotoxicity and neurodegeneration. As such, here we will review the role of lipids in the neuronal damage induced by ethanol-related oxidative stress and the role that lipids play in the related compensatory or defense mechanisms.

  9. Testing the Effects of DL-Alpha-Tocopherol Supplementation on Oxidative Damage, Total Antioxidant Protection and the Sex-Specific Responses of Reproductive Effort and Lifespan to Dietary Manipulation in Australian Field Crickets (Teleogryllus commodus

    Directory of Open Access Journals (Sweden)

    C. Ruth Archer

    2015-12-01

    Full Text Available The oxidative stress theory predicts that the accumulation of oxidative damage causes aging. More generally, oxidative damage could be a cost of reproduction that reduces survival. Both of these hypotheses have mixed empirical support. To better understand the life-history consequences of oxidative damage, we fed male and female Australian field crickets (Teleogryllus commodus four diets differing in their protein and carbohydrate content, which have sex-specific effects on reproductive effort and lifespan. We supplemented half of these crickets with the vitamin E isoform DL-alpha-tocopherol and measured the effects of nutrient intake on lifespan, reproduction, oxidative damage and antioxidant protection. We found a clear trade-off between reproductive effort and lifespan in females but not in males. In direct contrast to the oxidative stress theory, crickets fed diets that improved their lifespan had high levels of oxidative damage to proteins. Supplementation with DL-alpha-tocopherol did not significantly improve lifespan or reproductive effort. However, males fed diets that increased their reproductive investment experienced high oxidative damage to proteins. While this suggests that male reproductive effort could elevate oxidative damage, this was not associated with reduced male survival. Overall, these results provide little evidence that oxidative damage plays a central role in mediating life-history trade-offs in T. commodus.

  10. Superoxide radical-mediated photocatalytic oxidation of phenolic compounds over Ag{sup +}/TiO{sub 2}: Influence of electron donating and withdrawing substituents

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Jiadong [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing Engineering Research Center of Process Pollution Control, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Xie, Yongbing, E-mail: ybxie@ipe.ac.cn [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing Engineering Research Center of Process Pollution Control, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Han, Qingzhen [State Key Laboratory of Multi-phase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Cao, Hongbin [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing Engineering Research Center of Process Pollution Control, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300072 (China); Wang, Yujiao [Department of Chemical and Biomedical Engineering, University of Science and Technology Beijing (China); Nawaz, Faheem; Duan, Feng [National Engineering Laboratory for Hydrometallurgical Cleaner Production Technology, Beijing Engineering Research Center of Process Pollution Control, Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)

    2016-03-05

    Highlights: • A weak EWG benefited photocatalytic oxidation of phenols the most. • Phenolic compounds were dominantly oxidized by ·O{sub 2}{sup −}, rather than ·OH, {sup 1}O{sub 2} or h{sup +}. • ·O{sub 2}{sup −} preferred to nucleophilically attack EDG substituted phenols. • ·O{sub 2}{sup −} more likely electrophilically attacked EWG substituted phenols. • ·O{sub 2}{sup −} simultaneously nucleophilically and electrophilically assaulted p-chlorophenol. - Abstract: A comparative study was constructed to correlate the electronic property of the substituents with the degradation rates of phenolic compounds and their oxidation pathways under UV with Ag{sup +}/TiO{sub 2} suspensions. It was verified that a weak electron withdrawing substituent benefited photocatalytic oxidation the most, while an adverse impact appeared when a substituent was present with stronger electron donating or withdrawing ability. The addition of p-benzoquinone dramatically blocked the degradation, confirming superoxide radicals (·O{sub 2}{sup −}) as the dominant photooxidant, rather than hydroxyl radicals, singlet oxygen or positive holes, which was also independent of the substituent. Hammett relationship was established based on pseudo-first-order reaction kinetics, and it revealed two disparate reaction patterns between ·O{sub 2}{sup −} and phenolic compounds, which was further verified by the quantum chemical computation on the frontier molecular orbitals and Mulliken charge distributions of ·O{sub 2}{sup −} and phenolic compounds. It was found that electron donating group (EDG) substituted phenols were more likely nucleophilically attacked by ·O{sub 2}{sup −}, while ·O{sub 2}{sup −} preferred to electrophilically assault electron withdrawing group (EWG) substituted phenols. Exceptionally, electrophilic and nucleophilic attack by ·O{sub 2}{sup −} could simultaneously occur in p-chlorophenol degradation, consequently leading to its highest rate

  11. Study of the Radical Chain Mechanism of Hydrocarbon Oxidation for In Situ Combustion Process

    Directory of Open Access Journals (Sweden)

    Alexandra Ushakova

    2017-01-01

    Full Text Available Despite the abundance of in situ combustion models of oil oxidation, many of the effects are still beyond consideration. For example, until now, initial stages of oxidation were not considered from a position of radical chain process. This is a serious difficulty for the simulation of oil recovery process that involves air injection. To investigate the initial stages of oxidation, the paper considers the sequence of chemical reactions, including intermediate short-living compounds and radicals. We have attempted to correlate the main stages of the reaction with areas of heat release observed in the experiments. The system of differential equations based on the equations of oxidation reactions was solved. Time dependence of peroxides formation and start of heat release is analytically derived for the initial stages. We have considered the inhibition of initial oxidation stages by aromatic oil compounds and have studied the induction time in dependence on temperature. Chain ignition criteria for paraffins and crude oil in presence of core samples were obtained. The calculation results are compared with the stages of oxidation that arise by high-pressure differential scanning calorimetry. According to experimental observations we have determined which reactions are important for the process and which can be omitted or combined into one as insignificant.

  12. Manipulating radicals: Using cobalt to steer radical reactions

    OpenAIRE

    Chirilă, A.

    2017-01-01

    This thesis describes research aimed at understanding and exploiting metallo-radical reactivity and explores reactions mediated by square planar, low-spin cobalt(II) complexes. A primary goal was to uncover novel reactivity of discrete cobalt(III)-bound carbene radicals generated upon reaction of the cobalt(II) catalysts with carbene precursors. Another important goal was to replace cobalt(II)-porphyrin catalysts with cheaper and easier to prepare metallo-radical analogues. Therefore the cata...

  13. Evaluation of oxidative DNA damage promoted by storage in sperm from sex-reversed rainbow trout.

    Science.gov (United States)

    Pérez-Cerezales, S; Martínez-Páramo, S; Cabrita, E; Martínez-Pastor, F; de Paz, P; Herráez, M P

    2009-03-01

    Short-term storage and cryopreservation of sperm are two common procedures in aquaculture, used for routine practices in artificial insemination reproduction and gene banking, respectively. Nevertheless, both procedures cause injuries affecting sperm motility, viability, cell structure and DNA stability, which diminish reproductive success. DNA modification is considered extremely important, especially when sperm storage is carried out with gene banking purposes. DNA damage caused by sperm storage is not well characterized and previous studies have reported simple and double strand breaks that have been attributed to oxidative events promoted by the generation of free radicals during storage. The objective of this study was to reveal DNA fragmentation and to explore the presence of oxidized bases that could be produced by oxidative events during short-term storage and cryopreservation in sex-reversed rainbow trout (Oncorhynchus mykiss) spermatozoa. Sperm from six males was analyzed separately. Different aliquots of the samples were stored 2h (fresh) or 5 days at 4 degrees C or were cryopreserved. Then spermatozoa were analyzed using the Comet assay, as well as combining this method with digestion with two endonucleases from Escherichia coli (Endonuclease III, that cut in oxidized cytosines, and FPG, cutting in oxidized guanosines). Both storage procedures yielded DNA fragmentation, but only short-term storage oxidative events were clearly detected, showing that oxidative processes affect guanosines rather than cytosines. Cryopreservation increases DNA fragmentation but the presence of oxidized bases was not noticed, suggesting that mechanisms other than oxidative stress could be involved in DNA fragmentation promoted by freezing.

  14. Curcumin attenuates oxidative stress induced NFκB mediated inflammation and endoplasmic reticulum dependent apoptosis of splenocytes in diabetes.

    Science.gov (United States)

    Rashid, Kahkashan; Chowdhury, Sayantani; Ghosh, Sumit; Sil, Parames C

    2017-11-01

    The present study was aimed to determine the curative role of curcumin against diabetes induced oxidative stress and its associated splenic complications. Diabetes was induced in the experimental rats via the intraperitoneal administration of a single dose of STZ (65mgkg -1 body weight). Increased blood glucose and intracellular ROS levels along with decreased body weight, the activity of cellular antioxidant enzymes and GSH/GSSG ratio were observed in the diabetic animals. Histological assessment showed white pulp depletion and damaged spleen anatomy in these animals. Oral administration of curcumin at a dose of 100mgkg -1 body weight daily for 8weeks, however, restored these alterations. Investigation of the mechanism of hyperglycemia induced oxidative stress mediated inflammation showed upregulation of inflammatory cytokines, chemokines, adhesion molecules and increased translocation of NFκB into the nucleus. Moreover, ER stress dependent cell death showed induction of eIF2α and CHOP mediated signalling pathways as well as increment in the expression of GRP78, Caspase-12, Calpain-1, phospho JNK, phospho p38 and phospho p53 in the diabetic group. Alteration of Bax/Bcl-2 ratio; disruption of mitochondrial membrane potential, release of cytochrome-C from mitochondria and upregulation of caspase 3 along with the formation of characteristic DNA ladder in the diabetic animals suggest the involvement of mitochondria dependent apoptotic pathway in the splenic cells. Treatment with curcumin could, however, protect cells from inflammatory damage and ER as well as mitochondrial apoptotic death by restoring the alterations of these parameters. Our results suggest that curcumin has the potential to act as an anti-diabetic, anti-oxidant, anti-inflammatory and anti-apoptotic therapeutic against diabetes mediated splenic damage. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Possible involvement of membrane lipids peroxidation and oxidation of catalytically essential thiols of the cerebral transmembrane sodium pump as component mechanisms of iron-mediated oxidative stress-linked dysfunction of the pump's activity

    Directory of Open Access Journals (Sweden)

    T.I. Omotayo

    2015-04-01

    Full Text Available The precise molecular events defining the complex role of oxidative stress in the inactivation of the cerebral sodium pump in radical-induced neurodegenerative diseases is yet to be fully clarified and thus still open. Herein we investigated the modulation of the activity of the cerebral transmembrane electrogenic enzyme in Fe2+-mediated in vitro oxidative stress model. The results show that Fe2+ inhibited the transmembrane enzyme in a concentration dependent manner and this effect was accompanied by a biphasic generation of aldehydic product of lipid peroxidation. While dithiothreitol prevented both Fe2+ inhibitory effect on the pump and lipid peroxidation, vitamin E prevented only lipid peroxidation but not inhibition of the pump. Besides, malondialdehyde (MDA inhibited the pump by a mechanism not related to oxidation of its critical thiols. Apparently, the low activity of the pump in degenerative diseases mediated by Fe2+ may involve complex multi-component mechanisms which may partly involve an initial oxidation of the critical thiols of the enzyme directly mediated by Fe2+ and during severe progression of such diseases; aldehydic products of lipid peroxidation such as MDA may further exacerbate this inhibitory effect by a mechanism that is likely not related to the oxidation of the catalytically essential thiols of the ouabain-sensitive cerebral electrogenic pump.

  16. Accelerated aging in schizophrenia patients: the potential role of oxidative stress.

    Science.gov (United States)

    Okusaga, Olaoluwa O

    2014-08-01

    Several lines of evidence suggest that schizophrenia, a severe mental illness characterized by delusions, hallucinations and thought disorder is associated with accelerated aging. The free radical (oxidative stress) theory of aging assumes that aging occurs as a result of damage to cell constituents and connective tissues by free radicals arising from oxygen-associated reactions. Schizophrenia has been associated with oxidative stress and chronic inflammation, both of which also appear to reciprocally induce each other in a positive feedback manner. The buildup of damaged macromolecules due to increased oxidative stress and failure of protein repair and maintenance systems is an indicator of aging both at the cellular and organismal level. When compared with age-matched healthy controls, schizophrenia patients have higher levels of markers of oxidative cellular damage such as protein carbonyls, products of lipid peroxidation and DNA hydroxylation. Potential confounders such as antipsychotic medication, smoking, socio-economic status and unhealthy lifestyle make it impossible to solely attribute the earlier onset of aging-related changes or oxidative stress to having a diagnosis of schizophrenia. Regardless of whether oxidative stress can be attributed solely to a diagnosis of schizophrenia or whether it is due to other factors associated with schizophrenia, the available evidence is in support of increased oxidative stress-induced cellular damage of macromolecules which may play a role in the phenomenon of accelerated aging presumed to be associated with schizophrenia.

  17. Free radical scavenging activity and neuroprotective potentials of D138, one Cu(II)/Zn(II) Schiff-base complex derived from N,N'-bis(2-hydroxynaphthylmethylidene)-1,3-propanediamine.

    Science.gov (United States)

    Wang, Che; Cai, Zheng-Xu; You, Zhong-Lu; Guo, Hui-Shu; Shang, De-Jing; Wang, Xiao-Ling; Zhang, Liang; Ma, Li-Jie; Tan, Jun; Le, Wei-Dong; Li, Song

    2014-09-01

    There is increasing evidence that free radicals play an important role in neuronal damages induced by diabetes mellitus or cerebral ischemia insults. Antioxidants with free radical scavenging activities have been shown to be beneficial and neuroprotective for these pathological conditions. Here, we report free radical scavenging activity and neuroprotective potential of D138, one copper(II)/zinc(II) Schiff-base complex derived from N,N'-2(2-hydroxynaphthylmethylidene)-1,3-propanediamine. The data from three in vitro assays, 2,2-diphenyl-1-picrylhydrazyl assay, nitro blue tetrazolium assay and hydroxyl radical scavenging assay, indicated that D138 presented a potent free radical scavenging activity. The neuroprotective and antioxidative effects of D138 were further evaluated in vivo using bilateral common carotid artery occlusion (BCCAO) mouse model and streptozotocin (STZ) diabetic mouse model. Our results indicated that treatment of D138 significantly ameliorated the hippocampal neuronal damage and the oxidative stress levels in these animal models. Moreover, D138 also reversed the behavioral deficiencies induced by BCCAO or STZ, as assessed by Y-maze test and fear conditioning test. In conclusion, all these findings support that D138 exerts free radical scavenging and neuroprotective activities and has the potentials to be a potent therapeutic candidate for brain oxidative damage induced by cerebral ischemia or diabetes mellitus.

  18. Formation of hydroxyl radicals in the human lens is related to the severity of nuclear cataract

    DEFF Research Database (Denmark)

    Garner, B; Davies, Michael Jonathan; Truscott, R J

    2000-01-01

    Recent studies have identified specific hydroxylated amino acid oxidation products which strongly suggest the presence of hydroxyl radical (HO.)-damaged proteins in human cataractous lenses. In the present study, the ability of early stage (type II) and advanced (type IV) nuclear cataractous lens...

  19. Zinc protects HepG2 cells against the oxidative damage and DNA damage induced by ochratoxin A

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Juanjuan; Zhang, Yu [Laboratory of Food Safety and Molecular Biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083 (China); Xu, Wentao, E-mail: xuwentaoboy@sina.com [Laboratory of Food Safety and Molecular Biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083 (China); The Supervision, Inspection and Testing Center of Genetically Modified Organisms, Ministry of Agriculture, Beijing 100083 (China); Luo, YunBo [Laboratory of Food Safety and Molecular Biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083 (China); The Supervision, Inspection and Testing Center of Genetically Modified Organisms, Ministry of Agriculture, Beijing 100083 (China); Hao, Junran [Laboratory of Food Safety and Molecular Biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083 (China); Shen, Xiao Li [The Supervision, Inspection and Testing Center of Genetically Modified Organisms, Ministry of Agriculture, Beijing 100083 (China); Yang, Xuan [Laboratory of Food Safety and Molecular Biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083 (China); Li, Xiaohong [The Supervision, Inspection and Testing Center of Genetically Modified Organisms, Ministry of Agriculture, Beijing 100083 (China); Huang, Kunlun, E-mail: hkl009@163.com [Laboratory of Food Safety and Molecular Biology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083 (China); The Supervision, Inspection and Testing Center of Genetically Modified Organisms, Ministry of Agriculture, Beijing 100083 (China)

    2013-04-15

    Oxidative stress and DNA damage are the most studied mechanisms by which ochratoxin A (OTA) induces its toxic effects, which include nephrotoxicity, hepatotoxicity, immunotoxicity and genotoxicity. Zinc, which is an essential trace element, is considered a potential antioxidant. The aim of this paper was to investigate whether zinc supplement could inhibit OTA-induced oxidative damage and DNA damage in HepG2 cells and the mechanism of inhibition. The results indicated that that exposure of OTA decreased the intracellular zinc concentration; zinc supplement significantly reduced the OTA-induced production of reactive oxygen species (ROS) and decrease in superoxide dismutase (SOD) activity but did not affect the OTA-induced decrease in the mitochondrial membrane potential (Δψ{sub m}). Meanwhile, the addition of the zinc chelator N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) strongly aggravated the OTA-induced oxidative damage. This study also demonstrated that zinc helped to maintain the integrity of DNA through the reduction of OTA-induced DNA strand breaks, 8-hydroxy-2′-deoxyguanosine (8-OHdG) formation and DNA hypomethylation. OTA increased the mRNA expression of metallothionein1-A (MT1A), metallothionein2-A (MT2A) and Cu/Zn superoxide dismutase (SOD1). Zinc supplement further enhanced the mRNA expression of MT1A and MT2A, but it had no effect on the mRNA expression of SOD1 and catalase (CAT). Zinc was for the first time proven to reduce the cytotoxicity of OTA through inhibiting the oxidative damage and DNA damage, and regulating the expression of zinc-associated genes. Thus, the addition of zinc can potentially be used to reduce the OTA toxicity of contaminated feeds. - Highlights: ► OTA decreased the intracellular zinc concentration. ► OTA induced the formation of 8-OHdG in HepG2 cells. ► It was testified for the first time that OTA induced DNA hypomethylation. ► Zinc protects against the oxidative damage and DNA damage induced by

  20. Zinc protects HepG2 cells against the oxidative damage and DNA damage induced by ochratoxin A

    International Nuclear Information System (INIS)

    Zheng, Juanjuan; Zhang, Yu; Xu, Wentao; Luo, YunBo; Hao, Junran; Shen, Xiao Li; Yang, Xuan; Li, Xiaohong; Huang, Kunlun

    2013-01-01

    Oxidative stress and DNA damage are the most studied mechanisms by which ochratoxin A (OTA) induces its toxic effects, which include nephrotoxicity, hepatotoxicity, immunotoxicity and genotoxicity. Zinc, which is an essential trace element, is considered a potential antioxidant. The aim of this paper was to investigate whether zinc supplement could inhibit OTA-induced oxidative damage and DNA damage in HepG2 cells and the mechanism of inhibition. The results indicated that that exposure of OTA decreased the intracellular zinc concentration; zinc supplement significantly reduced the OTA-induced production of reactive oxygen species (ROS) and decrease in superoxide dismutase (SOD) activity but did not affect the OTA-induced decrease in the mitochondrial membrane potential (Δψ m ). Meanwhile, the addition of the zinc chelator N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) strongly aggravated the OTA-induced oxidative damage. This study also demonstrated that zinc helped to maintain the integrity of DNA through the reduction of OTA-induced DNA strand breaks, 8-hydroxy-2′-deoxyguanosine (8-OHdG) formation and DNA hypomethylation. OTA increased the mRNA expression of metallothionein1-A (MT1A), metallothionein2-A (MT2A) and Cu/Zn superoxide dismutase (SOD1). Zinc supplement further enhanced the mRNA expression of MT1A and MT2A, but it had no effect on the mRNA expression of SOD1 and catalase (CAT). Zinc was for the first time proven to reduce the cytotoxicity of OTA through inhibiting the oxidative damage and DNA damage, and regulating the expression of zinc-associated genes. Thus, the addition of zinc can potentially be used to reduce the OTA toxicity of contaminated feeds. - Highlights: ► OTA decreased the intracellular zinc concentration. ► OTA induced the formation of 8-OHdG in HepG2 cells. ► It was testified for the first time that OTA induced DNA hypomethylation. ► Zinc protects against the oxidative damage and DNA damage induced by OTA in

  1. Oxidation of carbon monoxide, hydrogen peroxide and water at a boron doped diamond electrode: the competition for hydroxyl radicals.

    Science.gov (United States)

    Kisacik, Izzet; Stefanova, Ana; Ernst, Siegfried; Baltruschat, Helmut

    2013-04-07

    Boron doped diamond (BDD) electrodes have an extremely high over-voltage for oxygen evolution from water, which favours its use in oxidation processes of other compounds at high potentials. We used a rotating ring disc (RRDE) assembly and differential electrochemical mass spectrometry (DEMS) in order to monitor the consumption or the production of species in the course of the electrode processes. By intercepting the intermediate of the electrochemical water oxidation with chemical reactions we demonstrate clearly, albeit indirectly, that in the water oxidation process at BDD above 2.5 V the first step is the formation of ˙OH radicals. The electro-oxidation of CO to CO2 at BDD electrodes proceeds only via a first attack by ˙OH radicals followed by a further electron transfer to the electrode. At potentials below the onset of oxygen evolution from water, H2O2 is oxidised by a direct electron transfer to the BDD electrode, while at higher potentials, two different reactions paths compete for the ˙OH radicals formed in the first electron transfer from water: one, where these ˙OH radicals react with each other followed by further electron transfers leading to O2 on the one hand and one, where ˙OH radicals react with other species like H2O2 or CO with subsequent electron transfers on the other hand.

  2. Anaerobic ammonium oxidation mediated by Mn-oxides: from sediment to strain level.

    Science.gov (United States)

    Javanaud, Cedric; Michotey, Valerie; Guasco, Sophie; Garcia, Nicole; Anschutz, Pierre; Canton, Mathieu; Bonin, Patricia

    2011-11-01

    Nitrite and (29)N(2) productions in slurry incubations of anaerobically sediment after (15)NO(3) or (15)NH(4) labelling in the presence of Mn-oxides suggested that anaerobic Mn-oxides mediated nitrification coupled with denitrification in muddy intertidal sediments of Arcachon Bay (SW Atlantic French coast). From this sediment, bacterial strains were isolated and physiologically characterized in terms of Mn-oxides and nitrate reduction as well as potential anaerobic nitrification. One of the isolated strain, identified as Marinobacter daepoensis strain M4AY14, was a denitrifier. Nitrous oxide production by this strain was demonstrated in the absence of nitrate and with Mn-oxides and NH(4) amendment, giving indirect proof of anaerobic nitrate or nitrite production. Anaerobic Mn-oxide-mediated nitrification was confirmed by (29)N(2) production in the presence of (15)NO(3) and (14)NH(4) under denitrifying conditions. Anaerobic nitrification by M4AY14 seemed to occur only in the absence of nitrate, or at nitrate levels lower than that of Mn-oxides. Most of the other isolates were affiliated with the Shewanella genus and were able to use both nitrate and Mn-oxides as electron acceptors. When both electron acceptors were present, whatever their concentrations, nitrate and Mn-oxide reduction co-occurred. These data indicate that bacterial Mn-oxide reduction could be an important process in marine sediments with low oxygen concentrations, and demonstrate for the first time the role of bacteria in anaerobic Mn-mediated nitrification. Copyright © 2011 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  3. Ceramide Production Mediates Aldosterone-Induced Human Umbilical Vein Endothelial Cell (HUVEC Damages.

    Directory of Open Access Journals (Sweden)

    Yumei Zhang

    Full Text Available Here, we studied the underlying mechanism of aldosterone (Aldo-induced vascular endothelial cell damages by focusing on ceramide. We confirmed that Aldo (at nmol/L inhibited human umbilical vein endothelial cells (HUVEC survival, and induced considerable cell apoptosis. We propose that ceramide (mainly C18 production might be responsible for Aldo-mediated damages in HUVECs. Sphingosine-1-phosphate (S1P, an anti-ceramide lipid, attenuated Aldo-induced ceramide production and following HUVEC damages. On the other hand, the glucosylceramide synthase (GCS inhibitor PDMP or the ceramide (C6 potentiated Aldo-induced HUVEC apoptosis. Eplerenone, a mineralocorticoid receptor (MR antagonist, almost completely blocked Aldo-induced C18 ceramide production and HUVEC damages. Molecularly, ceramide synthase 1 (CerS-1 is required for C18 ceramide production by Aldo. Knockdown of CerS-1 by targeted-shRNA inhibited Aldo-induced C18 ceramide production, and protected HUVECs from Aldo. Reversely, CerS-1 overexpression facilitated Aldo-induced C18 ceramide production, and potentiated HUVEC damages. Together, these results suggest that C18 ceramide production mediates Aldo-mediated HUVEC damages. MR and CerS-1 could be the two signaling molecule regulating C18 ceramide production by Aldo.

  4. Characterization of oxidative guanine damage and repair in mammalian telomeres.

    Directory of Open Access Journals (Sweden)

    Zhilong Wang

    2010-05-01

    Full Text Available 8-oxo-7,8-dihydroguanine (8-oxoG and 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyG are among the most common oxidative DNA lesions and are substrates for 8-oxoguanine DNA glycosylase (OGG1-initiated DNA base excision repair (BER. Mammalian telomeres consist of triple guanine repeats and are subject to oxidative guanine damage. Here, we investigated the impact of oxidative guanine damage and its repair by OGG1 on telomere integrity in mice. The mouse cells were analyzed for telomere integrity by telomere quantitative fluorescence in situ hybridization (telomere-FISH, by chromosome orientation-FISH (CO-FISH, and by indirect immunofluorescence in combination with telomere-FISH and for oxidative base lesions by Fpg-incision/Southern blot assay. In comparison to the wild type, telomere lengthening was observed in Ogg1 null (Ogg1(-/- mouse tissues and primary embryonic fibroblasts (MEFs cultivated in hypoxia condition (3% oxygen, whereas telomere shortening was detected in Ogg1(-/- mouse hematopoietic cells and primary MEFs cultivated in normoxia condition (20% oxygen or in the presence of an oxidant. In addition, telomere length abnormalities were accompanied by altered telomere sister chromatid exchanges, increased telomere single- and double-strand breaks, and preferential telomere lagging- or G-strand losses in Ogg1(-/- mouse cells. Oxidative guanine lesions were increased in telomeres in Ogg1(-/- mice with aging and primary MEFs cultivated in 20% oxygen. Furthermore, oxidative guanine lesions persisted at high level in Ogg1(-/- MEFs after acute exposure to hydrogen peroxide, while they rapidly returned to basal level in wild-type MEFs. These findings indicate that oxidative guanine damage can arise in telomeres where it affects length homeostasis, recombination, DNA replication, and DNA breakage repair. Our studies demonstrate that BER pathway is required in repairing oxidative guanine damage in telomeres and maintaining telomere integrity

  5. Studying mechanism of radical reactions: From radiation to nitroxides as research tools

    Science.gov (United States)

    Maimon, Eric; Samuni, Uri; Goldstein, Sara

    2018-02-01

    Radicals are part of the chemistry of life, and ionizing radiation chemistry serves as an indispensable research tool for elucidation of the mechanism(s) underlying their reactions. The ever-increasing understanding of their involvement in diverse physiological and pathological processes has expanded the search for compounds that can diminish radical-induced damage. This review surveys the areas of research focusing on radical reactions and particularly with stable cyclic nitroxide radicals, which demonstrate unique antioxidative activities. Unlike common antioxidants that are progressively depleted under oxidative stress and yield secondary radicals, nitroxides are efficient radical scavengers yielding in most cases their respective oxoammonium cations, which are readily reduced back in the tissue to the nitroxide thus continuously being recycled. Nitroxides, which not only protect enzymes, cells, and laboratory animals from diverse kinds of biological injury, but also modify the catalytic activity of heme enzymes, could be utilized in chemical and biological systems serving as a research tool for elucidating mechanisms underlying complex chemical and biochemical processes.

  6. Roles of the tyrosine isomers meta-tyrosine and ortho-tyrosine in oxidative stress.

    Science.gov (United States)

    Ipson, Brett R; Fisher, Alfred L

    2016-05-01

    The damage to cellular components by reactive oxygen species, termed oxidative stress, both increases with age and likely contributes to age-related diseases including Alzheimer's disease, atherosclerosis, diabetes, and cataract formation. In the setting of oxidative stress, hydroxyl radicals can oxidize the benzyl ring of the amino acid phenylalanine, which then produces the abnormal tyrosine isomers meta-tyrosine or ortho-tyrosine. While elevations in m-tyrosine and o-tyrosine concentrations have been used as a biological marker of oxidative stress, there is emerging evidence from bacterial, plant, and mammalian studies demonstrating that these isomers, particularly m-tyrosine, directly produce adverse effects to cells and tissues. These new findings suggest that the abnormal tyrosine isomers could in fact represent mediators of the effects of oxidative stress. Consequently the accumulation of m- and o-tyrosine may disrupt cellular homeostasis and contribute to disease pathogenesis, and as result, effective defenses against oxidative stress can encompass not only the elimination of reactive oxygen species but also the metabolism and ultimately the removal of the abnormal tyrosine isomers from the cellular amino acid pool. Future research in this area is needed to clarify the biologic mechanisms by which the tyrosine isomers damage cells and disrupt the function of tissues and organs and to identify the metabolic pathways involved in removing the accumulated isomers after exposure to oxidative stress. Published by Elsevier B.V.

  7. Beta-glucan ameliorates gamma-rays induced oxidative injury in male Swiss albino rats

    International Nuclear Information System (INIS)

    Salama, S.F.

    2011-01-01

    1,3-beta-D-Glucan is a natural polysaccharide derived from the cell walls of bakers yeast Saccharomyces cerevsiae with immunoenhancing and potent antioxidant effects. This study investigated the pathways through which beta-glucan gavage treatment (50mg/kg) exerts its effect on radiation-induced oxidative damage in male rats. Beta-glucan was given orally to male rats; 3 hours post gamma-irradiation at dose 5Gy, for 10 and 20 days post-irradiation level were assayed, being remarkable indicators in cell oxidative stress. Results pointed out that irradiation at 5Gy significantly depressed all blood parameters, such as erythrocytes count (RBCs), hemoglobin content (Hb), hematocrit value (Hct), total leucocytes count and absolute lymphocytes and neutrophils counts, blood glutathione (GSH) level and conversely elevated level of serum ascorbyl radical (AsR), product of lipid peroxidation (MDA melanodialdehyde), triglycerides and cholesterol. Total leucocytes count and absolute lymphocytes and neutrophils counts, RBCs, Hb, Hct, blood GSH and serum MDA of irradiated animals receiving beta-glucan administration were exhibited significant differences compared to the irradiated group. Marrow count and the percentage of viability and spleenocytes viability were also significantly decreased. Beta-glucan treatment accelerates recovery of cell damage induced by ionizing irradiation through its potential immune-enhancing activity and free radical scavenging ability that is partially mediated through stimulation of immunohaematological system thus could play a role in regulating irradiation complications

  8. Experimental study of oxidative DNA damage

    DEFF Research Database (Denmark)

    Loft, Steffen; Deng, Xin-Sheng; Tuo, Jingsheng

    1998-01-01

    Animal experiments allow the study of oxidative DNA damage in target organs and the elucidation of dose-response relationships of carcinogenic and other harmful chemicals and conditions as well as the study of interactions of several factors. So far the effects of more than 50 different chemical ...

  9. Oxidative DNA damage causes mitochondrial genomic instability in Saccharomyces cerevisiae.

    Science.gov (United States)

    Doudican, Nicole A; Song, Binwei; Shadel, Gerald S; Doetsch, Paul W

    2005-06-01

    Mitochondria contain their own genome, the integrity of which is required for normal cellular energy metabolism. Reactive oxygen species (ROS) produced by normal mitochondrial respiration can damage cellular macromolecules, including mitochondrial DNA (mtDNA), and have been implicated in degenerative diseases, cancer, and aging. We developed strategies to elevate mitochondrial oxidative stress by exposure to antimycin and H(2)O(2) or utilizing mutants lacking mitochondrial superoxide dismutase (sod2Delta). Experiments were conducted with strains compromised in mitochondrial base excision repair (ntg1Delta) and oxidative damage resistance (pif1Delta) in order to delineate the relationship between these pathways. We observed enhanced ROS production, resulting in a direct increase in oxidative mtDNA damage and mutagenesis. Repair-deficient mutants exposed to oxidative stress conditions exhibited profound genomic instability. Elimination of Ntg1p and Pif1p resulted in a synergistic corruption of respiratory competency upon exposure to antimycin and H(2)O(2). Mitochondrial genomic integrity was substantially compromised in ntg1Delta pif1Delta sod2Delta strains, since these cells exhibit a total loss of mtDNA. A stable respiration-defective strain, possessing a normal complement of mtDNA damage resistance pathways, exhibited a complete loss of mtDNA upon exposure to antimycin and H(2)O(2). This loss was preventable by Sod2p overexpression. These results provide direct evidence that oxidative mtDNA damage can be a major contributor to mitochondrial genomic instability and demonstrate cooperation of Ntg1p and Pif1p to resist the introduction of lesions into the mitochondrial genome.

  10. Radical transfer between proteins: role of tyrosine, tryptophan and protein peroxyl radicals

    International Nuclear Information System (INIS)

    Irwin, J.A.; Ostdal, H.; Davies, M.J.

    1998-01-01

    Reaction of the Fe(III) forms of the heme proteins myoglobin (Mb) and horseradish peroxidase (HRP) with H 2 O 2 gives rise to high-oxidation-state heme-derived species which can be described as a Fe(IV)-oxo porphyrin radical-cation ('Compound 1'). In the case of Mb, the Fe(IV)-oxo porphyrin radical-cation undergoes rapid electron transfer with the surrounding protein to give protein (globin)-derived radicals and an Fe(lV)-oxo species ('Compound 2'). The globin-derived radicals have been shown to be located at two (or more) sites: Tyr-103 or Trp-14, with the latter radical known to react with oxygen to give a Trp-derived peroxyl radical (Mb-Trp-OO*). With HRP, the Fe(lV)-oxo porphyrin radical-cation carries out two successive one-electron oxidation reactions at the exposed heme edge to give firstly 'Compound 2' [the Fe(lV)oxo species] and then the resting Fe(III) state of the enzyme. n this study we have investigated whether the Trp-14 peroxyl radical from Mb and the Compound 1 and 2 species from HRP (in the absence and presence of free Tyr) can oxidise amino acids, peptides and proteins. Such reactions constitute intermolecular protein-to-protein radical transfer reactions and hence protein chain-oxidation. We have also examined whether these oxidants react with antioxidants. Reaction of these heme-protein derived oxidants with amino acids, proteins and antioxidants has been carried out at room temperature for defined periods of time before freeze-quenching to 77K to halt reaction. The radical species present in the reaction system at the time of freezing were subsequently examined by EPR spectroscopy at 77K. Three free amino acids, Tyr, Trp and Cys (with Cys the least efficient) have been shown to react rapidly with Mb-Trp-OO*, as evidenced by the loss of the characteristic EPR features of Mb-Trp-OO* on inclusion of increasing concentrations of the amino acids. All other amino acids are much less reactive. Evidence has also been obtained for (inefficient) hydrogen

  11. Efficacy of wheat germ oil in modulating radiation-induced heart damage in rats

    International Nuclear Information System (INIS)

    Said, U.Z.; Azab, Kh.Sh.

    2006-01-01

    Wheat Germ oil is a natural unrefined vegetable oil. It is an excellent source of vitamin E, octacosanol, linoleic and linolenic essential fatty acids, which may be beneficial in neutralizing the free oxygen radicals. This study was designed to investigate the cardio-protective efficacy of wheat germ oil, on radiation-induced oxidative damage in rat's heart. Wheat germ oil was supplemented by gavage to rats at a dose of 81 mg/ kg body wt for 10 successive days pre- and 7 successive days post-exposure to 7 Gy (single dose) of whole body gamma irradiation. The dose of wheat germ oil is equivalent to daily human nutritional supplementation quantity. The results revealed that whole body ?-irradiation of rats produced significant alterations in blood cells picture. The erythrocyte, leucocyte, platelet counts and hemoglobin levels decreased after irradiation. Also, radiation-induced biochemical disorders manifested by significant elevation in xanthine oxidase activity (XO) and thiobarbituric acid reactive substances (TBARS) level, with decrease in reduced glutathione (GSH) content in heart tissues, indicating depression in the antioxidant status. Serum lipid profile as total cholesterol, high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C) and triglycerides levels (TG) were significantly higher than normal control rats. Radiation exposure produced a significant rise in the activities of serum markers for heart damage as creatine phosphokinase (CPK), aspartate aminotransferase (AST) and lactic dehydrogenase (LDH) indicating acute cardiac toxicity. Moreover, the obtained results revealed abnormal electrophoretic pattern of LDH isoenzymes in the 7th day after exposure to gamma rays. Three bands only appear on the agarose film comparing with 4 bands in normal control rats. The rats that received wheat germ oil supplement showed significantly less severe damage and remarkable improvement in all of the measured parameters when compared to

  12. CaNa2EDTA chelation attenuates cell damage in workers exposed to lead--a pilot study.

    Science.gov (United States)

    Čabarkapa, A; Borozan, S; Živković, L; Stojanović, S; Milanović-Čabarkapa, M; Bajić, V; Spremo-Potparević, B

    2015-12-05

    Lead induced oxidative cellular damage and long-term persistence of associated adverse effects increases risk of late-onset diseases. CaNa2EDTA chelation is known to remove contaminating metals and to reduce free radical production. The objective was to investigate the impact of chelation therapy on modulation of lead induced cellular damage, restoration of altered enzyme activities and lipid homeostasis in peripheral blood of workers exposed to lead, by comparing the selected biomarkers obtained prior and after five-day CaNa2EDTA chelation intervention. The group of smelting factory workers diagnosed with lead intoxication and current lead exposure 5.8 ± 1.2 years were administered five-day CaNa2EDTA chelation. Elevated baseline activity of antioxidant enzymes Cu, Zn-SOD and CAT as well as depleted thiols and increased protein degradation products-carbonyl groups and nitrites, pointing to Pb induced oxidative damage, were restored toward normal values following the treatment. Lead showed inhibitor potency on both RBC AChE and BChE in exposed workers, and chelation re-established the activity of BChE, while RBC AChE remained unaffected. Also, genotoxic effect of lead detected in peripheral blood lymphocytes was significantly decreased after therapy, exhibiting 18.9% DNA damage reduction. Administration of chelation reversed the depressed activity of serum PON 1 and significantly decreased lipid peroxidation detected by the post-chelation reduction of MDA levels. Lactate dehydrogenase LDH1-5 isoenzymes levels showed evident but no significant trend of restoring toward normal control values following chelation. CaNa2EDTA chelation ameliorates the alterations linked with Pb mediated oxidative stress, indicating possible benefits in reducing health risks associated with increased oxidative damage in lead exposed populations. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  13. Nitric oxide is a mediator of methamphetamine (METH)-induced neurotoxicity. In vitro evidence from primary cultures of mesencephalic cells.

    Science.gov (United States)

    Sheng, P; Cerruti, C; Ali, S; Cadet, J L

    1996-10-31

    METH is a monoaminergic toxic that destroys dopamine terminals in vivo. Oxidative mechanisms associated with DA metabolism are thought to play an important role in its toxic effects. These ideas were supported by the demonstration that CuZn-superoxide dismutase (CuZnSOD) transgenic mice were protected against the toxic effects of the drug. In the present study, we sought to determine if nitric oxide (NO) production was also involved in METH-induced neurotoxicity using primary cultures obtained from fetal rat mesencephalon. METH caused dose- and time-dependent cell death in vitro. Blockade of nitric oxide (NO) formation with several nitric oxide (NO) synthase blockers attenuated METH-mediated toxicity. Moreover, inhibition of ADP-ribosylation with nicotinamide and benzamide also provided protection against the toxicity of the drug. These results, together with our previous results in transgenic mice, support a role for free radicals in METH-induced toxic effects.

  14. 4-Alkyl radical extrusion in the cytochrome P-450-catalyzed oxidation of 4-alkyl-1,4-dihydropyridines

    International Nuclear Information System (INIS)

    Lee, J.S.; Jacobsen, N.E.; Ortiz de Montellano, P.R.

    1988-01-01

    Rat liver microsomal cytochrome P-450 oxidizes the 4-methyl, 4-ethyl (DDEP), and 4-isopropyl derivatives of 3,5-bis(carbethoxy)-2,6-dimethyl-1,4,-dihydropyridine to mixtures of the corresponding 4-alkyl and 4-dealkyl pyridines. A fraction of the total microsomal enzyme is destroyed in the process. The 4-dealkyl to 4-alkyl pyridine metabolite ratio, the extent of cytochrome P-450 destruction, and the rate of spin-trapped radical accumulation are correlated in a linear inverse manner with the homolytic or heterolytic bond energies of the 4-alkyl groups of the 4-alkyl-1,4-dihydropyridines. No isotope effects are observed on the pyridine matabolite ratio, the destruction of cytochrome P-450, or the formation of ethyl radicals when [4- 2 H]DDEP is used instead of DDEP. N-Methyl- and N-ethyl-DDEP undergo N-dealkylation rather than aromatization but N-phenyl-DDEP is oxidized to a mixture of the 4-ethyl and 4-deethyl N-phenylpyridinium metabolites. In contrast to the absence of an isotope effect in the oxidation of DDEP, the 4-deethyl to 4-ethyl N-phenylpyridinium metabolite ratio increases 6-fold when N-phenyl[4- 2 H]DDEP is used. The results support the hypothesis that cytochrome P-450 catalyzes the oxidation of dihydropyridines to radical cations and show that the radical cations decay to nonradical products by multiple, substituent-dependent, mechanisms

  15. Spin Trapping Radicals from Lipid Oxidation in Liposomes in the Presence of Flavonoids

    International Nuclear Information System (INIS)

    Arshad, N.

    2013-01-01

    Interactions of four structurally related flavonoids - quercetin, rutin, morin and catechin with peroxyl radicals using liposome/N-tert-butyl-alpha-phenylnitrone (PBN) and liposome -(4-pyridyl-N-oxide)-N-tert-butylnitrone (POBN)-spin trap systems have been studied through spin trapping ESR. Results obtained were different from that of conjugated diene analysis experiments, where lag phases indicated radical scavenging activity of all the flavonoids. No clear lag phase was observed in ESR experiments under same conditions. In the presence of flavonoids decreasing ESR signals of spin adducts in PBN, while no or negligibly smaller spin adducts with POBN system were observed which may be attributed to the possibility that spin traps interacted with free radicals. Experiments with buffer/spin trap systems without liposome revealed that spin adducts were only stable with catechin and destroyed by quercetin, rutin and morin in buffer/spin trap systems. These results further assured that quercetin, rutin and morin not only interacted with peroxyl radicals but also with spin adducts. (author)

  16. Protective role of S-Adenosylmethionine against fructose-induced oxidative damage in obesity

    Directory of Open Access Journals (Sweden)

    Kameliya Zh Bratoeva

    2017-10-01

    Full Text Available Introduction. It has been shown that S-adenosylmethionine (S-AMe stimulates glutathione synthesis and increases cell resistance to the cytotoxic action of free radicals and pro-inflammatory cytokines. The aim of this study was to determine the effect of Sadenosylmethionine on the oxidative stress in adipose tissue in a model of fructose-induced obesity. Methods. The study was performed on male Wistar rats divided into 3 groups: control, fructose fed (HFD (35%, 16 weeks, and HFD + S-AMe (20 mg/kg. We examined the changes in the ratio of retroperitoneal adipose tissue weight / body weight; levels of reduced glutathione (GSH and malondialdehyde (MDA in the retroperitoneal adipose tissue, and serum levels of GSH and TNF-α. Results. Significant increases in the retroperitoneal adipose tissue, MDA, and serum TNF-α were identified, as well as decreased tissue and serum levels of GSH in rats fed with a high-fructose diet as compared with the control group. In the group fed with HFD and SAMe, we found significant reduction in the retroperitoneal adipose tissue and decreased levels of MDA and serum TNF-α, as well as increased tissue and serum levels of GSH as compared with the group only on HFD. In conclusion, our results show that fructose-induced obesity causes oxidative stress in hypertrophic visceral adipose tissue. The administration of S-AMe improves the antioxidative protection of adipocytes, and reduces oxidative damage and excessive accumulation of lipids and inflammation.

  17. Bis(formylphenolatocobalt(II-Mediated Alternating Radical Copolymerization of tert-Butyl 2-Trifluoromethylacrylate with Vinyl Acetate

    Directory of Open Access Journals (Sweden)

    Sanjib Banerjee

    2017-12-01

    Full Text Available The organometallic-mediated radical polymerization (OMRP of vinyl acetate (VAc and its OMR copolymerization (OMRcoP with tert-butyl 2-trifluoromethylacrylate (MAF-TBE mediated by Co(SAL2 (SAL = 2-formylphenolato or deprotonated salicylaldehyde produced relatively well-defined PVAc and poly(VAc-alt-MAF-TBE copolymers at moderate temperature (<40 °C in bulk. The resulting alternating copolymer was characterized by 1H-, 13C- and 19F-nuclear magnetic resonance (NMR spectroscopies, and by size exclusion chromatography. The linear first-order kinetic plot, the linear evolutions of the molar mass with total monomer conversion, and the relatively low dispersity (Đ~1.55 of the resulting copolymers suggest that this cobalt complex provides some degree of control over the copolymerization of VAc and MAF-TBE. Compared to the previously investigated cobalt complex OMRP mediators having a fully oxygen-based first coordination sphere, this study emphasizes a few peculiarities of Co(SAL2: a lower ability to trap radical chains as compared to Co(acac2 and the absence of catalytic chain transfer reactions, which dominates polymerizations carried in the presence of 9-oxyphenalenone cobalt derivative.

  18. Neuroprotection by Radical Avoidance: Search for Suitable Agents

    Directory of Open Access Journals (Sweden)

    Rüdiger Hardeland

    2009-12-01

    Full Text Available Neurodegeneration is frequently associated with damage by free radicals. However, increases in reactive oxygen and nitrogen species, which may ultimately lead to neuronal cell death, do not necessarily reflect its primary cause, but can be a consequence of otherwise induced cellular dysfunction. Detrimental processes which promote free radical formation are initiated, e.g., by disturbances in calcium homeostasis, mitochondrial malfunction, and an age-related decline in the circadian oscillator system. Free radicals generated at high rates under pathophysiological conditions are insufficiently detoxified by scavengers. Interventions at the primary causes of dysfunction, which avoid secondary rises in radical formation, may be more efficient. The aim of such approaches should be to prevent calcium overload, to reduce mitochondrial electron dissipation, to support electron transport capacity, and to avoid circadian perturbations. l-Theanine and several amphiphilic nitrones are capable of counteracting excitotoxicity and/or mitochondrial radical formation. Resveratrol seems to promote mitochondrial biogenesis. Mitochondrial effects of leptin include attenuation of electron leakage. Melatonin combines all the requirements mentioned, additionally regulates anti- and pro-oxidant enzymes and is, with few exceptions, very well tolerated. In this review, the perspectives, problems and limits of drugs are compared which may be suitable for reducing the formation of free radicals.

  19. Effect of flavoring chemicals on free radical formation in electronic cigarette aerosols.

    Science.gov (United States)

    Bitzer, Zachary T; Goel, Reema; Reilly, Samantha M; Elias, Ryan J; Silakov, Alexey; Foulds, Jonathan; Muscat, Joshua; Richie, John P

    2018-05-20

    Flavoring chemicals, or flavorants, have been used in electronic cigarettes (e-cigarettes) since their inception; however, little is known about their toxicological effects. Free radicals present in e-cigarette aerosols have been shown to induce oxidative stress resulting in damage to proliferation, survival, and inflammation pathways in the cell. Aerosols generated from e-liquid solvents alone contain high levels of free radicals but few studies have looked at how these toxins are modulated by flavorants. We investigated the effects of different flavorants on free radical production in e-cigarette aerosols. Free radicals generated from 49 commercially available e-liquid flavors were captured and analyzed using electron paramagnetic resonance (EPR). The flavorant composition of each e-liquid was analyzed by gas chromatography mass spectroscopy (GCMS). Radical production was correlated with flavorant abundance. Ten compounds were identified and analyzed for their impact on free radical generation. Nearly half of the flavors modulated free radical generation. Flavorants with strong correlations included β-damascone, δ-tetradecalactone, γ-decalactone, citral, dipentene, ethyl maltol, ethyl vanillin, ethyl vanillin PG acetal, linalool, and piperonal. Dipentene, ethyl maltol, citral, linalool, and piperonal promoted radical formation in a concentration-dependent manner. Ethyl vanillin inhibited the radical formation in a concentration dependent manner. Free radical production was closely linked with the capacity to oxidize biologically-relevant lipids. Our results suggest that flavoring agents play an important role in either enhancing or inhibiting the production of free radicals in flavored e-cigarette aerosols. This information is important for developing regulatory strategies aimed at reducing potential harm from e-cigarettes. Copyright © 2018 Elsevier Inc. All rights reserved.

  20. Hydroxyl-radical-induced oxidation of cyclic dipeptides: Reactions of free peptide radicals and their peroxyl radicals

    International Nuclear Information System (INIS)

    Mieden, O.J.

    1989-01-01

    In the course of this study investigations were carried out into the reactions of hydroxyl radicals and hydrogen atoms with cyclic dipeptides as well as the subsequent reactions of peptide radicals and their peroxyl radicals in aqueous solution. The radiolysis products formed in the absence and presence of oxygen or transient metal complexes were characterized and determined on a quantitative basis. The linking of information from product analyses to the kinetic data for transient species obtained by time-resolving UV/VIS and conductivity measurements (pulse radiolysis) as well as computer-assisted simulations of individual events during the reaction permitted an evaluation of the mechanisms underlying the various processes and an identification of interim products with short life-times, which did or did not belong to the group of radicals. Through the characterization of key reactions of radicals and peroxyl radicals of this substance class a major advance has been made towards a better understanding of the role of radicals in the peptide compound and the mechanisms involved in indirect radiation effects on long-chain peptides and proteins. (orig.) [de

  1. Chloro-benquinone Modified on Graphene Oxide as Metal-free Catalyst: Strong Promotion of Hydroxyl Radical and Generation of Ultra-Small Graphene Oxide

    Science.gov (United States)

    Zhao, He; Wang, Juehua; Zhang, Di; Dai, Qin; Han, Qingzhen; Du, Penghui; Liu, Chenming; Xie, Yongbing; Zhang, Yi; Cao, Hongbin; Fan, Zhuangjun

    2017-03-01

    Carbon-based metal-free catalyst has attracted more and more attention. It is a big challenge to improve catalytic activity of metal-free catalyst for decomposition of H2O2 to produce hydroxyl radical (HO•). Here, we report chloro-benquinone (TCBQ) modified on graphene oxide (GO) as metal-free catalyst for strong promotion of HO•. By the incorporation of GO, the HO• production by H2O2 and TCBQ is significantly promoted. Based on density functional theory, TCBQ modified GO (GO-TCBQ) is more prone to be nucleophilic attacked by H2O2 to yield HO• via electron transfer acceleration. Furthermore, the generated HO• can cut GO nanosheets into uniform ultra-small graphene oxide (USGO) through the cleavage of epoxy and C-C bonds. Interestingly, the damaged GO and in situ formed GO fragments can further enhance decomposition of H2O2 to produce HO•. Different from other catalytic processes, the GO-TCBQ metal-free catalysis process can be enhanced by GO itself, producing more HO•, and uniform USGO also can be generated. Thus, the metal free catalysis will be considered a fabrication method for uniform USGO, and may be extended to other fields including detoxifying organic pollutants and the application as disinfectants.

  2. Oxidative damage and antioxidant defense in thymus of malnourished lactating rats.

    Science.gov (United States)

    Gavia-García, Graciela; González-Martínez, Haydeé; Miliar-García, Ángel; Bonilla-González, Edmundo; Rosas-Trejo, María de Los Ángeles; Königsberg, Mina; Nájera-Medina, Oralia; Luna-López, Armando; González-Torres, María Cristina

    2015-01-01

    Malnutrition has been associated with oxidative damage by altered antioxidant protection mechanisms. Specifically, the aim of this study was to evaluate oxidative damage (DNA and lipid) and antioxidant status (superoxide dismutase [SOD], glutathione peroxidase [GPx], and catalase [CAT] mRNA, and protein expression) in thymus from malnourished rat pups. Malnutrition was induced during the lactation period by the food competition method. Oxidative DNA damage was determined quantifying 8-oxo-7, 8-dihydro-2'-deoxyguanosine adduct by high-performance liquid chromatography. Lipid peroxidation was assessed by the formation of thiobarbituric acid-reactive substances. Levels of gene and protein expression of SOD, GPx, and CAT were evaluated by real-time polymerase chain reaction and Western blot, respectively. Antioxidant enzyme activities were measured spectrophotometrically. Oxidative DNA damage and lipid peroxidation significantly increased in second-degree (MN-2) and third-degree malnourished (MN-3) rats compared with well-nourished rats. Higher amounts of oxidative damage, lower mRNA expression, and lower relative concentrations of protein, as well as decreased antioxidant activity of SOD, GPx, and CAT were associated with the MN-2 and MN-3 groups. The results of this study demonstrated that higher body-weight deficits were related to alterations in antioxidant protection, which contribute to increased levels of damage in the thymus. To our knowledge, this study demonstrated for the first time that early in life, malnutrition leads to increased DNA and lipid oxidative damage, attributable to damaged antioxidant mechanisms including transcriptional and enzymatic activity alterations. These findings may contribute to the elucidation of the causes of previously reported thymus dysfunction, and might explain partially why children and adults who have overcome child undernourishment experience immunologic deficiencies. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Detection of DNA damage by using hairpin molecular beacon probes and graphene oxide.

    Science.gov (United States)

    Zhou, Jie; Lu, Qian; Tong, Ying; Wei, Wei; Liu, Songqin

    2012-09-15

    A hairpin molecular beacon tagged with carboxyfluorescein in combination with graphene oxide as a quencher reagent was used to detect the DNA damage by chemical reagents. The fluorescence of molecular beacon was quenched sharply by graphene oxide; while in the presence of its complementary DNA the quenching efficiency decreased because their hybridization prevented the strong adsorbability of molecular beacon on graphene oxide. If the complementary DNA was damaged by a chemical reagent and could not form intact duplex structure with molecular beacon, more molecular beacon would adsorb on graphene oxide increasing the quenching efficiency. Thus, damaged DNA could be detected based on different quenching efficiencies afforded by damaged and intact complementary DNA. The damage effects of chlorpyrifos-methyl and three metabolites of styrene such as mandelieaeids, phenylglyoxylieaeids and epoxystyrene on DNA were studied as models. The method for detection of DNA damage was reliable, rapid and simple compared to the biological methods. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Reactivity Of Radiolytically-Produced Nitrogen Oxide Radicals Toward Aromatic Compounds

    International Nuclear Information System (INIS)

    Elias, Gracy

    2010-01-01

    The nitration of aromatic compounds in the gas phase is an important source of toxic, carcinogenic, and mutagenic species in the atmosphere and has therefore received much attention. Gas phase nitration typically occurs by free-radical reactions. Condensed-phase free-radical reactions, and in particular nitrite and nitrate radical chemistry, have been studied far less. These condensed-phase free-radical reactions may be relevant in fog and cloud water in polluted areas, in urban aerosols with low pH, in water treatment using advanced oxidation processes such as electron beam (e-beam) irradiation, and in nuclear waste treatment applications. This study discusses research toward an improved understanding of nitration of aromatic compounds in the condensed phase under conditions conducive to free-radical formation. The results are of benefit in several areas of environmental chemistry, in particular nuclear waste treatment applications. The nitration reactions of anisole and toluene as model compounds were investigated in γ-irradiated acidic nitrate, neutral nitrate, and neutral nitrite solutions. Cs-7SB, 1-(2,2,3,3,-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol, is used as a solvent modifier in the fission product extraction (FPEX) formulation for the extraction of Cs and Sr from dissolved nuclear fuel. The formulation also contains the ligands calix(4)arene-bis-(tert-octylbenzo-crown-6) (BOBCalixC6) for Cs extraction and 4,4(prime),(5(prime))-di-(t-butyldicyclohexano)-18-crown-6 (DtBuCH18C6) for Sr extraction, all in Isopar L, a branched-chain alkane diluent. FPEX solvent has favorable extraction efficiency for Cs and Sr from acidic solution and was investigated at the Idaho National Laboratory (INL) for changes in extraction efficiency after γ-irradiation. Extraction efficiency decreased after irradiation. The decrease in solvent extraction efficiency was identical for Cs and Sr, even though they are complexed by different ligands. This suggests that

  5. Chlorine as a primary radical: evaluation of methods to understand its role in initiation of oxidative cycles

    Science.gov (United States)

    Young, C. J.; Washenfelder, R. A.; Edwards, P. M.; Parrish, D. D.; Gilman, J. B.; Kuster, W. C.; Mielke, L. H.; Osthoff, H. D.; Tsai, C.; Pikelnaya, O.; Stutz, J.; Veres, P. R.; Roberts, J. M.; Griffith, S.; Dusanter, S.; Stevens, P. S.; Flynn, J.; Grossberg, N.; Lefer, B.; Holloway, J. S.; Peischl, J.; Ryerson, T. B.; Atlas, E. L.; Blake, D. R.; Brown, S. S.

    2014-04-01

    The role of chlorine atoms (Cl) in atmospheric oxidation has been traditionally thought to be limited to the marine boundary layer, where they are produced through heterogeneous reactions involving sea salt. However, recent observation of photolytic Cl precursors (ClNO2 and Cl2) formed from anthropogenic pollution has expanded the potential importance of Cl to include coastal and continental urban areas. Measurements of ClNO2 in Los Angeles during CalNex (California Nexus - Research at the Nexus of Air Quality and Climate Change) showed it to be an important primary (first generation) radical source. Evolution of ratios of volatile organic compounds (VOCs) has been proposed as a method to quantify Cl oxidation, but we find no evidence from this approach for a significant role of Cl oxidation in Los Angeles. We use a box model with the Master Chemical Mechanism (MCM v3.2) chemistry scheme, constrained by observations in Los Angeles, to examine the Cl sensitivity of commonly used VOC ratios as a function of NOx and secondary radical production. Model results indicate VOC tracer ratios could not detect the influence of Cl unless the ratio of [OH] to [Cl] was less than 200 for at least a day. However, the model results also show that secondary (second generation) OH production resulting from Cl oxidation of VOCs is strongly influenced by NOx, and that this effect obscures the importance of Cl as a primary oxidant. Calculated concentrations of Cl showed a maximum in mid-morning due to a photolytic source from ClNO2 and loss primarily to reactions with VOCs. The [OH] to [Cl] ratio was below 200 for approximately 3 h in the morning, but Cl oxidation was not evident from the measured ratios of VOCs. Instead, model simulations show that secondary OH production causes VOC ratio evolution to follow that expected for OH oxidation, despite the significant input of primary Cl from ClNO2 photolysis in the morning. Even though OH is by far the dominant oxidant in Los Angeles, Cl

  6. Cerium oxide nanoparticles, combining antioxidant and UV shielding properties, prevent UV-induced cell damage and mutagenesis

    Science.gov (United States)

    Caputo, Fanny; de Nicola, Milena; Sienkiewicz, Andrzej; Giovanetti, Anna; Bejarano, Ignacio; Licoccia, Silvia; Traversa, Enrico; Ghibelli, Lina

    2015-09-01

    Efficient inorganic UV shields, mostly based on refracting TiO2 particles, have dramatically changed the sun exposure habits. Unfortunately, health concerns have emerged from the pro-oxidant photocatalytic effect of UV-irradiated TiO2, which mediates toxic effects on cells. Therefore, improvements in cosmetic solar shield technology are a strong priority. CeO2 nanoparticles are not only UV refractors but also potent biological antioxidants due to the surface 3+/4+ valency switch, which confers anti-inflammatory, anti-ageing and therapeutic properties. Herein, UV irradiation protocols were set up, allowing selective study of the extra-shielding effects of CeO2vs. TiO2 nanoparticles on reporter cells. TiO2 irradiated with UV (especially UVA) exerted strong photocatalytic effects, superimposing their pro-oxidant, cell-damaging and mutagenic action when induced by UV, thereby worsening the UV toxicity. On the contrary, irradiated CeO2 nanoparticles, via their Ce3+/Ce4+ redox couple, exerted impressive protection on UV-treated cells, by buffering oxidation, preserving viability and proliferation, reducing DNA damage and accelerating repair; strikingly, they almost eliminated mutagenesis, thus acting as an important tool to prevent skin cancer. Interestingly, CeO2 nanoparticles also protect cells from the damage induced by irradiated TiO2, suggesting that these two particles may also complement their effects in solar lotions. CeO2 nanoparticles, which intrinsically couple UV shielding with biological and genetic protection, appear to be ideal candidates for next-generation sun shields.

  7. Activation of glutathione peroxidase via Nrf1 mediates genistein's protection against oxidative endothelial cell injury

    International Nuclear Information System (INIS)

    Hernandez-Montes, Eva; Pollard, Susan E.; Vauzour, David; Jofre-Montseny, Laia; Rota, Cristina; Rimbach, Gerald; Weinberg, Peter D.; Spencer, Jeremy P.E.

    2006-01-01

    Cellular actions of isoflavones may mediate the beneficial health effects associated with high soy consumption. We have investigated protection by genistein and daidzein against oxidative stress-induced endothelial injury. Genistein but not daidzein protected endothelial cells from damage induced by oxidative stress. This protection was accompanied by decreases in intracellular glutathione levels that could be explained by the generation of glutathionyl conjugates of the oxidised genistein metabolite, 5,7,3',4'-tetrahydroxyisoflavone. Both isoflavones evoked increased protein expression of γ-glutamylcysteine synthetase-heavy subunit (γ-GCS-HS) and increased cytosolic accumulation and nuclear translocation of Nrf2. However, only genistein led to increases in the cytosolic accumulation and nuclear translocation of Nrf1 and the increased expression of and activity of glutathione peroxidase. These results suggest that genistein-induced protective effects depend primarily on the activation of glutathione peroxidase mediated by Nrf1 activation, and not on Nrf2 activation or increases in glutathione synthesis

  8. Broccoli (Brassica oleracea) Reduces Oxidative Damage to Pancreatic Tissue and Combats Hyperglycaemia in Diabetic Rats.

    Science.gov (United States)

    Suresh, Sithara; Waly, Mostafa Ibrahim; Rahman, Mohammad Shafiur; Guizani, Nejib; Al-Kindi, Mohamed Abdullah Badar; Al-Issaei, Halima Khalfan Ahmed; Al-Maskari, Sultan Nasser Mohd; Al-Ruqaishi, Bader Rashid Said; Al-Salami, Ahmed

    2017-12-01

    Oxidative stress plays a pivotal role in the development of diabetes and hyperglycaemia. The protective effects of natural extracts against diabetes are mainly dependent on their antioxidant and hypoglycaemic properties. Broccoli ( Brassica oleracea ) exerts beneficial health effects in several diseases including diabetes; however, the mechanism has not been elucidated yet. The present study was carried out to evaluate the potential hypoglycaemic and antioxidant properties of aqueous broccoli extracts (BEs) in diabetic rats. Streptozotocin (STZ) drug was used as a diabetogenic agent in a single intraperitoneal injection dose of 50 mg/kg body weight. The blood glucose level for each rat was measured twice a week. After 8 weeks, all animals were fasted overnight and sacrificed; pancreatic tissues were homogenized and used for measuring oxidative DNA damage, biochemical assessment of glutathione (GSH), and total antioxidant capacity (TAC) as well as histopathological examination for pancreatic tissues was examined. Diabetic rats showed significantly higher levels of DNA damage, GSH depletion, and impaired TAC levels in comparison to non-diabetics ( P <0.05). The treatment of diabetic rats with BE significantly reduced DNA damage and conserved GSH and TAC values ( P <0.01). BE attenuated pancreatic histopathological changes in diabetic rats. The results of this study indicated that BE reduced the STZ mediated hyperglycaemia and the STZ-induced oxidative injury to pancreas tissue. The used in vivo model confirmed the efficacy of BE as an anti-diabetic herbal medicine and provided insights into the capacity of BE to be used for phytoremediation purposes for human type 2 diabetes.

  9. Therapeutic Hypothermia Reduces Oxidative Damage and Alters Antioxidant Defenses after Cardiac Arrest

    Science.gov (United States)

    Hackenhaar, Fernanda S.; Medeiros, Tássia M.; Heemann, Fernanda M.; Behling, Camile S.; Putti, Jordana S.; Mahl, Camila D.; Verona, Cleber; da Silva, Ana Carolina A.; Guerra, Maria C.; Gonçalves, Carlos A. S.; Oliveira, Vanessa M.; Riveiro, Diego F. M.; Vieira, Silvia R. R.

    2017-01-01

    After cardiac arrest, organ damage consequent to ischemia-reperfusion has been attributed to oxidative stress. Mild therapeutic hypothermia has been applied to reduce this damage, and it may reduce oxidative damage as well. This study aimed to compare oxidative damage and antioxidant defenses in patients treated with controlled normothermia versus mild therapeutic hypothermia during postcardiac arrest syndrome. The sample consisted of 31 patients under controlled normothermia (36°C) and 11 patients treated with 24 h mild therapeutic hypothermia (33°C), victims of in- or out-of-hospital cardiac arrest. Parameters were assessed at 6, 12, 36, and 72 h after cardiac arrest in the central venous blood samples. Hypothermic and normothermic patients had similar S100B levels, a biomarker of brain injury. Xanthine oxidase activity is similar between hypothermic and normothermic patients; however, it decreases posthypothermia treatment. Xanthine oxidase activity is positively correlated with lactate and S100B and inversely correlated with pH, calcium, and sodium levels. Hypothermia reduces malondialdehyde and protein carbonyl levels, markers of oxidative damage. Concomitantly, hypothermia increases the activity of erythrocyte antioxidant enzymes superoxide dismutase, glutathione peroxidase, and glutathione S-transferase while decreasing the activity of serum paraoxonase-1. These findings suggest that mild therapeutic hypothermia reduces oxidative damage and alters antioxidant defenses in postcardiac arrest patients. PMID:28553435

  10. Oxidative shielding and the cost of reproduction.

    Science.gov (United States)

    Blount, Jonathan D; Vitikainen, Emma I K; Stott, Iain; Cant, Michael A

    2016-05-01

    Life-history theory assumes that reproduction and lifespan are constrained by trade-offs which prevent their simultaneous increase. Recently, there has been considerable interest in the possibility that this cost of reproduction is mediated by oxidative stress. However, empirical tests of this theory have yielded equivocal support. We carried out a meta-analysis to examine associations between reproduction and oxidative damage across markers and tissues. We show that oxidative damage is positively associated with reproductive effort across females of various species. Yet paradoxically, categorical comparisons of breeders versus non-breeders reveal that transition to the reproductive state is associated with a step-change reduction in oxidative damage in certain tissues and markers. Developing offspring may be particularly sensitive to harm caused by oxidative damage in mothers. Therefore, such reductions could potentially function to shield reproducing mothers, gametes and developing offspring from oxidative insults that inevitably increase as a consequence of reproductive effort. According to this perspective, we hypothesise that the cost of reproduction is mediated by dual impacts of maternally-derived oxidative damage on mothers and offspring, and that mothers may be selected to diminish such damage. Such oxidative shielding may explain why many existing studies have concluded that reproduction has little or no oxidative cost. Future advance in life-history theory therefore needs to take account of potential transgenerational impacts of the mechanisms underlying life-history trade-offs. © 2015 Cambridge Philosophical Society.

  11. Transmission of Free Radicals through and Damage to Freestanding Single and Multilayer Dielectric Film

    Science.gov (United States)

    Choudhury, Faraz Anwar

    and FTIR measurements both reveal that the oxygen plasma exposure leads to surface oxidation of the silicon dioxide film and the formation of a denser surface layer which restricts the transmission of the radicals through the film. It was found that the extent of modification of the film partially depends on the radical dose. The calculated enthalpies of the reactions show that they are all exothermic reactions, however, the radicals need enough energy to overcome the activation energy for the reaction to take place.

  12. Free terminal amines in DNA-binding peptides alter the product distribution from guanine radicals produced by single electron oxidation.

    Science.gov (United States)

    Konigsfeld, Katie M; Lee, Melissa; Urata, Sarah M; Aguilera, Joe A; Milligan, Jamie R

    2012-03-01

    Electron deficient guanine radical species are major intermediates produced in DNA by the direct effect of ionizing irradiation. There is evidence that they react with amine groups in closely bound ligands to form covalent crosslinks. Crosslink formation is very poorly characterized in terms of quantitative rate and yield data. We sought to address this issue by using oligo-arginine ligands to model the close association of DNA and its binding proteins in chromatin. Guanine radicals were prepared in plasmid DNA by single electron oxidation. The product distribution derived from them was assayed by strand break formation after four different post-irradiation incubations. We compared the yields of DNA damage produced in the presence of four ligands in which neither, one, or both of the amino and carboxylate termini were blocked with amides. Free carboxylate groups were unreactive. Significantly higher yields of heat labile sites were observed when the amino terminus was unblocked. The rate of the reaction was characterized by diluting the unblocked amino group with its amide blocked derivative. These observations provide a means to develop quantitative estimates for the yields in which these labile sites are formed in chromatin by exposure to ionizing irradiation.

  13. Role of reactive oxygen intermediates in the interferon-mediated depression of hepatic drug metabolism and protective effect of N-acetylcysteine in mice.

    Science.gov (United States)

    Ghezzi, P; Bianchi, M; Gianera, L; Landolfo, S; Salmona, M

    1985-08-01

    Interferon (IFN) and IFN inducers are known to depress hepatic microsomal cytochrome P-450 levels, and the liver toxicity of IFN was reported to be lethal in newborn mice. We have observed that administration to mice of IFN and IFN inducers caused a marked increase in liver xanthine oxidase activity. Because this enzyme is well known to produce reactive oxygen intermediates and cytochrome P-450 was reported to be sensitive to the oxidative damage, we have tested the hypothesis that a free radical mechanism could mediate the depression of cytochrome P-450 levels by IFN. Administration to mice of the IFN inducer polyinosinic-polycytidylic acid (2 mg/kg i.p.) caused a 29 to 52% decrease in liver cytochrome P-450. Concomitant p.o. administration of the free radical scavenger, N-acetylcysteine (as a 2.5% solution in drinking water), or the xanthine oxidase inhibitor, allopurinol (100 mg/kg), protected against the IFN-mediated depression of P-450 kg), protected against the IFN-mediated depression of P-450 levels. The results suggest that an increased endogenous generation of free radicals, possibly due to the induction of xanthine oxidase, is implicated in the IFN-mediated depression of liver drug metabolism. The relevance of these data also extends to cases in which this side effect is observed in pathological situations (e.g., viral diseases and administration of vaccines) associated with an induction of IFN.

  14. Transgenic Mouse Model for Reducing Oxidative Damage in Bone

    Science.gov (United States)

    Schreurs, Ann-Sofie; Torres, S.; Truong, T.; Moyer, E. L.; Kumar, A.; Tahimic, Candice C. G.; Alwood, J. S.; Limoli, C. L.; Globus, R. K.

    2016-01-01

    Bone loss can occur due to many challenges such age, radiation, microgravity, and Reactive Oxygen Species (ROS) play a critical role in bone resorption by osteoclasts (Bartell et al. 2014). We hypothesize that suppression of excess ROS in skeletal cells, both osteoblasts and osteoclasts, regulates skeletal growth and remodeling. To test our hypothesis, we used transgenic mCAT mice which overexpress the human anti-oxidant catalase gene targeted to the mitochondria, the main site for endogenous ROS production. mCAT mice have a longer life-span than wildtype controls and have been used to study various age-related disorders. To stimulate remodeling, 16 week old mCAT mice or wildtype mice were exposed to treatment (hindlimb-unloading and total body-irradiation) or sham treatment conditions (control). Tissues were harvested 2 weeks later for skeletal analysis (microcomputed tomography), biochemical analysis (gene expression and oxidative damage measurements), and ex vivo bone marrow derived cell culture (osteoblastogenesis and osteoclastogenesis). mCAT mice expressed the transgene and displayed elevated catalase activity in skeletal tissue and marrow-derived osteoblasts and osteoclasts grown ex vivo. In addition, when challenged with treatment, bone tissues from wildtype mice showed elevated levels of malondialdehyde (MDA), indicating oxidative damage) whereas mCAT mice did not. Correlation analysis revealed that increased catalase activity significantly correlated with decreased MDA levels and that increased oxidative damage correlated with decreased percent bone volume (BVTV). In addition, ex-vivo cultured osteoblast colony growth correlated with catalase activity in the osteoblasts. Thus, we showed that these transgenic mice can be used as a model to study the relationship between markers of oxidative damage and skeletal properties. mCAT mice displayed reduced BVTV and trabecular number relative to wildtype mice, as well as increased structural model index in the

  15. Anti-Oxidative, Metal Chelating and Radical Scavenging Effects of ...

    African Journals Online (AJOL)

    ... (8): 1349-1355. ISSN: 1596-5996 (print); 1596-9827 (electronic) ... 3 kDa fraction against oxidative protein damage were comparable to that of reduced glutathione. ... optimum temperatures of each protease, namely .... exhibited concentration-dependent increase in .... Ability of Ethanol Extracts of Hypericum Scabrum L.

  16. Theoretical perspectives on the mechanism and kinetics of the OH radical-initiated gas-phase oxidation of PCB126 in the atmosphere

    International Nuclear Information System (INIS)

    Dang, Juan; Shi, Xiangli; Zhang, Qingzhu; Wang, Wenxing

    2015-01-01

    Polychlorinated biphenyls (PCBs) primarily exist in the gas phase in air and may undergo atmospheric oxidation degradations, particularly the oxidation reaction initiated by OH radicals. In this work, the mechanism of the OH radical-initiated atmospheric oxidation of the most toxic PCB congener 3,3′,4,4′,5-pentachlorobiphenyl (PCB126) was investigated by using quantum chemistry methods. The rate constants of the crucial elementary reactions were estimated by the Rice–Ramsperger–Kassel–Marcus (RRKM) theory. The oxidation products of the reaction of PCB126 with OH radicals include 3,3′,4,4′,5-pentachlorobiphenyl-ols, chlorophenols, 2,3,4,7,8-pentachlorodibenzofuran, 2,3,4,6,7-pentachlorodibenzofuran, dialdehydes, 3,3′,4,4′,5-pentachloro-5′-nitro-biphenyl, and 4,5-dichloro-2-nitrophenol. Particularly, the formation of polychlorinated dibenzofurans (PCDFs) from the atmospheric oxidation of PCBs is revealed for the first time. The overall rate constant of the OH addition reaction is 2.52 × 10 −13 cm 3 molecule −1 s −1 at 298 K and 1 atm. The atmospheric lifetime of PCB126 determined by OH radicals is about 47.08 days which indicates that PCB126 can be transported long distances from local to global scales. - Highlights: • A comprehensive mechanism of OH-initiated oxidation of PCB126 was investigated. • The formation of PCDFs from the oxidation of PCBs is determined for the first time. • The rate constants for key elementary reactions were estimated by the RRKM theory. • The atmospheric lifetime of PCB126 determined by OH radicals is about 47.08 days

  17. Rhesus monkey lens as an in vitro model for studying oxidative stress