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Sample records for oxygen species scavenging

  1. Development of nitroxide radicals-containing polymer for scavenging reactive oxygen species from cigarette smoke

    NASA Astrophysics Data System (ADS)

    Yoshitomi, Toru; Kuramochi, Kazuhiro; Binh Vong, Long; Nagasaki, Yukio

    2014-06-01

    We developed a nitroxide radicals-containing polymer (NRP), which is composed of poly(4-methylstyrene) possessing nitroxide radicals as a side chain via amine linkage, to scavenge reactive oxygen species (ROS) from cigarette smoke. In this study, the NRP was coated onto cigarette filters and its ROS-scavenging activity from streaming cigarette smoke was evaluated. The intensity of electron spin resonance signals of the NRP in the filter decreased after exposure to cigarette smoke, indicating consumption of nitroxide radicals. To evaluate the ROS-scavenging activity of the NRP-coated filter, the amount of peroxy radicals in an extract of cigarette smoke was measured using UV-visible spectrophotometry and 1,1-diphenyl-2-picrylhydrazyl (DPPH). The absorbance of DPPH at 517 nm decreased with exposure to cigarette smoke. When NRP-coated filters were used, the decrease in the absorbance of DPPH was prevented. In contrast, both poly[4-(cyclohexylamino)methylstyrene]- and poly(acrylic acid)-coated filters, which have no nitroxide radical, did not show any effect, indicating that the nitroxide radicals in the NRP scavenge the ROS in cigarette smoke. As a result, the extract of cigarette smoke passed through the NRP-coated filter has a lower cellular toxicity than smoke passed through poly[4-(cyclohexylamino)methylstyrene]- and poly(acrylic acid)-coated filters. Accordingly, NRP is a promising material for ROS scavenging from cigarette smoke.

  2. Development of nitroxide radicals-containing polymer for scavenging reactive oxygen species from cigarette smoke.

    PubMed

    Yoshitomi, Toru; Kuramochi, Kazuhiro; Binh Vong, Long; Nagasaki, Yukio

    2014-06-01

    We developed a nitroxide radicals-containing polymer (NRP), which is composed of poly(4-methylstyrene) possessing nitroxide radicals as a side chain via amine linkage, to scavenge reactive oxygen species (ROS) from cigarette smoke. In this study, the NRP was coated onto cigarette filters and its ROS-scavenging activity from streaming cigarette smoke was evaluated. The intensity of electron spin resonance signals of the NRP in the filter decreased after exposure to cigarette smoke, indicating consumption of nitroxide radicals. To evaluate the ROS-scavenging activity of the NRP-coated filter, the amount of peroxy radicals in an extract of cigarette smoke was measured using UV-visible spectrophotometry and 1,1-diphenyl-2-picrylhydrazyl (DPPH). The absorbance of DPPH at 517 nm decreased with exposure to cigarette smoke. When NRP-coated filters were used, the decrease in the absorbance of DPPH was prevented. In contrast, both poly[4-(cyclohexylamino)methylstyrene]- and poly(acrylic acid)-coated filters, which have no nitroxide radical, did not show any effect, indicating that the nitroxide radicals in the NRP scavenge the ROS in cigarette smoke. As a result, the extract of cigarette smoke passed through the NRP-coated filter has a lower cellular toxicity than smoke passed through poly[4-(cyclohexylamino)methylstyrene]- and poly(acrylic acid)-coated filters. Accordingly, NRP is a promising material for ROS scavenging from cigarette smoke.

  3. Compartment-specific Control of Reactive Oxygen Species Scavenging by Antioxidant Pathway Enzymes.

    PubMed

    Dey, Swati; Sidor, Agnieszka; O'Rourke, Brian

    2016-05-20

    Oxidative stress arises from an imbalance in the production and scavenging rates of reactive oxygen species (ROS) and is a key factor in the pathophysiology of cardiovascular disease and aging. The presence of parallel pathways and multiple intracellular compartments, each having its own ROS sources and antioxidant enzymes, complicates the determination of the most important regulatory nodes of the redox network. Here we quantified ROS dynamics within specific intracellular compartments in the cytosol and mitochondria and determined which scavenging enzymes exert the most control over antioxidant fluxes in H9c2 cardiac myoblasts. We used novel targeted viral gene transfer vectors expressing redox-sensitive GFP fused to sensor domains to measure H2O2 or oxidized glutathione. Using genetic manipulation in heart-derived H9c2 cells, we explored the contribution of specific antioxidant enzymes to ROS scavenging and glutathione redox potential within each intracellular compartment. Our findings reveal that antioxidant flux is strongly dependent on mitochondrial substrate catabolism, with availability of NADPH as a major rate-controlling step. Moreover, ROS scavenging by mitochondria significantly contributes to cytoplasmic ROS handling. The findings provide fundamental information about the control of ROS scavenging by the redox network and suggest novel interventions for circumventing oxidative stress in cardiac cells.

  4. Resveratrol scavenges reactive oxygen species and effects radical-induced cellular responses.

    PubMed

    Leonard, Stephen S; Xia, Chang; Jiang, Bin-Hua; Stinefelt, Beth; Klandorf, Hillar; Harris, Gabriel K; Shi, Xianglin

    2003-10-03

    Scavenging or quenching of the reactive oxygen species (ROS) involved in oxidative stress has been the subject of many recent studies. Resveratrol, found in various natural food products, has been linked to decreased coronary artery disease and preventing cancer development. The present study measured the effect of resveratrol on several different systems involving the hydroxyl, superoxide, metal/enzymatic-induced, and cellular generated radicals. The rate constant for reaction of resveratrol with the hydroxyl radical was determined, and resveratrol was found to be an effective scavenger of hydroxyl, superoxide, and metal-induced radicals as well as showing antioxidant abilities in cells producing ROS. Resveratrol exhibits a protective effect against lipid peroxidation in cell membranes and DNA damage caused by ROS. Resveratrol was also found to have a significant inhibitory effect on the NF-kappaB signaling pathway after cellular exposure to metal-induced radicals. It was concluded that resveratrol in foods plays an important antioxidant role.

  5. The potential of extracts of Caryocar villosum pulp to scavenge reactive oxygen and nitrogen species.

    PubMed

    Chisté, Renan Campos; Freitas, Marisa; Mercadante, Adriana Zerlotti; Fernandes, Eduarda

    2012-12-01

    Caryocar villosum (piquiá) is a native fruit from the Amazonian region, considered to be an interesting source of bioactive compounds. In this paper, five extracts of C. villosum pulp were obtained, using solvents with different polarities and their in vitro scavenging capacity against reactive oxygen species (ROS) and reactive nitrogen species (RNS) was determined. Additionally, the phenolic compounds and carotenoids in each extract were identified and quantified by a high performance liquid chromatography coupled to diode array and mass spectrometer detectors (HPLC-DAD-MS/MS). The ethanol/water and water extracts, which presented the highest phenolic contents (5163 and 1745μg/g extract, respectively), with ellagic acid as the major phenolic compound, proved to have the highest ROS and RNS scavenging potential. Nevertheless, in general, ellagic acid was less effective in scavenging ROS (IC(50) from 1.7 to 108μg/ml) and RNS (IC(50) from 0.05 to 0.59μg/ml), when compared to gallic acid (IC(50) from 0.4 to 226μg/ml for ROS and IC(50) from 0.04 to 0.12μg/ml for RNS). The results obtained in the present study clearly demonstrated that the in vitro antioxidant efficiency of C. villosum extracts was closely related to their contents of phenolic compounds.

  6. Vitamin B1 as a scavenger of reactive oxygen species photogenerated by vitamin B2.

    PubMed

    Natera, José; Massad, Walter A; García, Norman A

    2011-01-01

    Kinetics and mechanism of photoprocesses generated by visible light-irradiation of the system riboflavin (Rf, vitamin B2) plus Thiamine (Th) and Thiamine pyrophosphate (ThDP), representing vitamin B1, was studied in pH 7 water. A weak dark complex vitamin B2-vitamin B1, with a mean value of 4 ± 0.4 M(-1) is formed. An intricate mechanism of competitive reactions operates upon photoirradiation, being the light only absorbed by Rf. Th and ThDP quench excited singlet and triplet states of Rf, with rate constants in the order of 10(9) and 10(6 ) M(-1 ) s(-1), respectively. With Vitamin B1 in a concentration similar to that of dissolved molecular oxygen in water, the quenching of triplet excited Rf by the latter is highly predominant, resulting in the generation of O(2)((1)Δ(g)). Superoxide radical anion was not detected under work conditions. A relatively slow O(2)((1)Δ(g))-mediated photodegradation of Th and ThDP was observed. Nevertheless, Th and especially ThDP behave as efficient physical deactivators of O(2)((1)Δ(g)). The thiazol structure in vitamin B1 appears as a good scavenger of this reactive oxygen species. This characteristic, that presents at vitamin B1 as a potential photoprotector of biological entities against O(2)((1)Δ(g)) attack, was been experimentally confirmed employing the protein lisozime as a photo-oxidizable target.

  7. Role of Free Radicals/Reactive Oxygen Species in MeHg Photodegradation: Importance of Utilizing Appropriate Scavengers.

    PubMed

    Han, Xiaoxiao; Li, Yanbin; Li, Dan; Liu, Chang

    2017-04-04

    A variety of free radicals (FR)/reactive oxygen species (ROS) have been proposed to dominate methylmercury (MeHg) photodegradation, primarily based on the results of FR/ROS scavenger addition experiments. However, in addition to eliminating FR/ROS, the added scavengers may also affect the experimental results by altering some water chemical properties, resulting in a misleading assessment of the importance of FR/ROS. In this study, 20 common FR/ROS scavengers were evaluated in terms of their influence on light absorbance, pH, MeHg analysis, MeHg-dissolved organic matter (DOM) complexation, and the scavenger-induced degradation of MeHg. Only nine scavengers were identified to be appropriate for investigating MeHg photodegradation. By utilizing these appropriate scavengers, direct photodegradation of MeHg-DOM complexes was found to be the major pathway of MeHg photodegradation in Laoshan Reservoir water and Stone Old Beach seawater. In contrast, MeHg photodegradation in Ink River water primarily occurs through both ·OH and (3)DOM* mediated indirect pathways and direct photodegradation of MeHg-DOM complexes. The diverse pathways of MeHg photodegradation in the tested water may be due to differences in water chemical properties. A severe overestimation of the role of FR/ROS was observed when several improper but commonly used scavengers were adopted, highlighting the necessity of utilizing appropriate scavengers.

  8. Reaction and Scavenging Mechanism of β-Carotene and Zeaxanthin with Reactive Oxygen Species.

    PubMed

    Nishino, Azusa; Yasui, Hiroyuki; Maoka, Takashi

    2017-01-01

    In order to investigate chemical scavenging mechanism of singlet oxygen, superoxide anion radical, and hydroxyl radical by carotenoids, reaction products obtained by reacting β-carotene or zeaxanthin with singlet oxygen, superoxide anion radical, and hydroxyl radical were analyzed by LC/PDA ESI-MS, and ESR spectrometry. β-Carotene endoperoxides were identified as the major reaction products of β-carotene and singlet oxygen, while β-carotene epoxides were the major reaction products of β-carotene and superoxide anion or hydroxyl radical. Similar results to those for β-carotene were obtained with zeaxanthin.

  9. Scoparone attenuates RANKL-induced osteoclastic differentiation through controlling reactive oxygen species production and scavenging

    SciTech Connect

    Lee, Sang-Hyun; Jang, Hae-Dong

    2015-02-15

    Scoparone, one of the bioactive components of Artemisia capillaris Thunb, has various biological properties including immunosuppressive, hepatoprotective, anti-allergic, anti-inflammatory, and antioxidant effects. This study aims at evaluating the anti-osteoporotic effect of scoparone and its underlying mechanism in vitro. Scoparone demonstrated potent cellular antioxidant capacity. It was also found that scoparone inhibited the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation and suppressed cathepsin K and tartrate-resistant acid phosphatase (TRAP) expression via c-jun N-terminal kinase (JNK)/extracellular signal-regulated kinase (ERK)/p38-mediated c-Fos–nuclear factor of activated T cells, cytoplasmic 1 (NFATc1) signaling pathway. During osteoclast differentiation, the production of general reactive oxygen species (ROS) and superoxide anions was dose-dependently attenuated by scoparone. In addition, scoparone diminished NADPH (nicotinamide adenine dinucleotide phosphate) oxidase 1 (Nox1) expression and activation via the tumor necrosis factor receptor-associated factor 6 (TRAF6)–cSrc–phosphatidylinositol 3-kinase (PI3k) signaling pathway and prevented the disruption of mitochondrial electron transport chain system. Furthermore, scoparone augmented the expression of superoxide dismutase 1 (SOD1) and catalase (CAT). The overall results indicate that the inhibitory effect of scoparone on RANKL-induced osteoclast differentiation is attributed to the suppressive effect on ROS and superoxide anion production by inhibiting Nox1 expression and activation and protecting the mitochondrial electron transport chain system and the scavenging effect of ROS resulting from elevated SOD1 and CAT expression. - Highlights: • Scoparone dose-dependently inhibited RANKL-induced osteoclast differentiation. • Scoparone diminished general ROS and superoxide anions in a dose-dependent manner. • Scoparone inhibited Nox1 expression and

  10. Global regulation of reactive oxygen species scavenging genes in alfalfa root and shoot under gradual drought stress and recovery.

    PubMed

    Kang, Yun; Udvardi, Michael

    2012-05-01

    Reactive oxygen species (ROS) production and scavenging in plants under drought stress have been studied intensively in recent years. Here we report a global analysis of gene expression for the major ROS generating and scavenging proteins in alfalfa root and shoot under gradual drought stress followed by one-day recovery. Data from two alfalfa varieties, one drought tolerant and one drought sensitive, were compared and no qualitative differences in ROS gene regulation between the two were found. Conserved, tissue-specific patterns of gene expression in response to drought were observed for several ROS-scavenging gene families, including ascorbate peroxidase, monodehydroascorbate reductase, and peroxiredoxin. In addition, differential gene expression within families was observed. Genes for the ROS-generating enzyme, NADPH oxidase were generally induced under drought, while those for glycolate oxidase were repressed. Among the ROS-scavenging protein genes, Ferritin, Cu/Zn superoxide dismutase (SOD), and the majority of the glutathione peroxidase family members were induced under drought in both roots and shoots of both alfalfa varieties. In contrast, Fe-SOD, CC-type glutaredoxins, and thoiredoxins were downregulated.

  11. Psidium cattleianum fruit extracts are efficient in vitro scavengers of physiologically relevant reactive oxygen and nitrogen species.

    PubMed

    Ribeiro, Alessandra Braga; Chisté, Renan Campos; Freitas, Marisa; da Silva, Alex Fiori; Visentainer, Jesuí Vergílio; Fernandes, Eduarda

    2014-12-15

    Psidium cattleianum, an unexploited Brazilian native fruit, is considered a potential source of bioactive compounds. In the present study, the in vitro scavenging capacity of skin and pulp extracts from P. cattleianum fruits against reactive oxygen species (ROS) and reactive nitrogen species (RNS) was evaluated by in vitro screening assays. Additionally, the composition of phenolic compounds and carotenoids in both extracts was determined by LC-MS/MS. The major phenolic compounds identified and quantified (dry matter) in the skin and pulp extracts of P. cattleianum were ellagic acid (2213-3818 μg/g extracts), ellagic acid deoxyhexoside (1475-2,070 μg/g extracts) and epicatechin gallate (885-1,603 μg/g extracts); while all-trans-lutein (2-10 μg/g extracts), all-trans-antheraxanthin (1.6-9 μg/g extracts) and all-trans-β-carotene (4-6 μg/g extracts) were the major carotenoids identified in both extracts. P. cattleianum pulp extract showed higher scavenging capacity than skin extract for all tested ROS and RNS. Considering the potential beneficial effects to human health, P. cattleianum may be considered as a good source of natural antioxidants and may be useful for the food and phytopharmaceutical industry.

  12. Reactive Oxygen Species Generation-Scavenging and Signaling during Plant-Arbuscular Mycorrhizal and Piriformospora indica Interaction under Stress Condition

    PubMed Central

    Nath, Manoj; Bhatt, Deepesh; Prasad, Ram; Gill, Sarvajeet S.; Anjum, Naser A.; Tuteja, Narendra

    2016-01-01

    A defined balance between the generation and scavenging of reactive oxygen species (ROS) is essential to utilize ROS as an adaptive defense response of plants under biotic and abiotic stress conditions. Moreover, ROS are not only a major determinant of stress response but also act as signaling molecule that regulates various cellular processes including plant-microbe interaction. In particular, rhizosphere constitutes the biologically dynamic zone for plant–microbe interactions which forms a mutual link leading to reciprocal signaling in both the partners. Among plant–microbe interactions, symbiotic associations of arbuscular mycorrhizal fungi (AMF) and arbuscular mycorrhizal-like fungus especially Piriformospora indica with plants are well known to improve plant growth by alleviating the stress-impacts and consequently enhance the plant fitness. AMF and P. indica colonization mainly enhances ROS-metabolism, maintains ROS-homeostasis, and thereby averts higher ROS-level accrued inhibition in plant cellular processes and plant growth and survival under stressful environments. This article summarizes the major outcomes of the recent reports on the ROS-generation, scavenging and signaling in biotic-abiotic stressed plants with AMF and P. indica colonization. Overall, a detailed exploration of ROS-signature kinetics during plant-AMF/P. indica interaction can help in designing innovative strategies for improving plant health and productivity under stress conditions. PMID:27818671

  13. Response to temperature stress of reactive oxygen species scavenging enzymes in the cross-tolerance of barley seed germination.

    PubMed

    Mei, Yu-qin; Song, Song-quan

    2010-12-01

    A number of studies have shown the existence of cross-tolerance in plants, but the physiological mechanism is poorly understood. In this study, we used the germination of barley seeds as a system to investigate the cross-tolerance of low-temperature pretreatment to high-temperature stress and the possible involvement of reactive oxygen species (ROS) scavenging enzymes in the cross-tolerance. After pretreatment at 0 °C for different periods of time, barley seeds were germinated at 35 °C, and the content of malondialdehyde (MDA) and the activities of ROS scavenging enzymes were measured by a spectrophotometer analysis. The results showed that barley seed germinated very poorly at 35 °C, and this inhibitive effect could be overcome by pretreatment at 0 °C. The MDA content varied, depending on the temperature at which seeds germinated, while barley seeds pretreated at 0 °C did not change the MDA content. Compared with seeds germinated directly at 35 °C, the seeds pretreated first at 0 °C and then germinated at 35 °C had markedly increased activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), and glutathione reductase (GR). The SOD and APX activities of seeds germinated at 35 °C after 0 °C-pretreatment were even substantially higher than those at 25 °C, and GR activity was similar to that at 25 °C, at which the highest germination performance of barley seeds was achieved. These results indicate that low-temperature pretreatment can markedly increase the tolerance of barley seed to high temperature during germination, this being related to the increase in ROS scavenging enzyme activity. This may provide a new method for increasing seed germination under stress environments, and may be an excellent model system for the study of cross-tolerance.

  14. Alliin Attenuated RANKL-Induced Osteoclastogenesis by Scavenging Reactive Oxygen Species through Inhibiting Nox1

    PubMed Central

    Chen, Yueqi; Sun, Jingjing; Dou, Ce; Li, Nan; Kang, Fei; Wang, Yuan; Cao, Zhen; Yang, Xiaochao; Dong, Shiwu

    2016-01-01

    The healthy skeleton requires a perfect coordination of the formation and degradation of bone. Metabolic bone disease like osteoporosis is resulted from the imbalance of bone formation and/or bone resorption. Osteoporosis also reflects lower level of bone matrix, which is contributed by up-regulated osteoclast-mediated bone resorption. It is reported that monocytes/macrophage progenitor cells or either hematopoietic stem cells (HSCs) gave rise to multinucleated osteoclasts. Thus, inhibition of osteoclastic bone resorption generally seems to be a predominant therapy for treating osteoporosis. Recently, more and more natural compounds have been discovered, which have the ability of inhibiting osteoclast differentiation and fusion. Alliin (S-allyl-l-cysteine sulfoxides, SACSO) is the major component of aged garlic extract (AGE), bearing broad-spectrum natural antioxidant properties. However, its effects on bone health have not yet been explored. Hence, we designed the current study to explore its effects and role in receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast fusion and differentiation. It was revealed that alliin had an inhibitory effect in osteoclasteogenesis with a dose-dependent manner via blocking the c-Fos-NFATc1 signaling pathway. In addition, alliin decreased the generation of reactive oxygen species (ROS) and down-regulated the expression of NADPH oxidase 1 (Nox1). The overall results revealed that alliin could be a potential therapeutic agent in the treatment of osteoporosis. PMID:27657047

  15. Mechanisms of nitric oxide crosstalk with reactive oxygen species scavenging enzymes during abiotic stress tolerance in plants.

    PubMed

    Arora, Dhara; Jain, Prachi; Singh, Neha; Kaur, Harmeet; Bhatla, Satish C

    2016-01-01

    Nitric oxide (NO) acts in a concentration and redox-dependent manner to counteract oxidative stress either by directly acting as an antioxidant through scavenging reactive oxygen species (ROS), such as superoxide anions (O(2)(-)*), to form peroxynitrite (ONOO(-)) or by acting as a signaling molecule, thereby altering gene expression. NO can interact with different metal centres in proteins, such as heme-iron, zinc-sulfur clusters, iron-sulfur clusters, and copper, resulting in the formation of a stable metal-nitrosyl complex or production of varied biochemical signals, which ultimately leads to modification of protein structure/function. The thiols (ferrous iron-thiol complex and nitrosothiols) are also involved in the metabolism and mobilization of NO. Thiols bind to NO and transport it to the site of action whereas nitrosothiols release NO after intercellular diffusion and uptake into the target cells. S-nitrosoglutathione (GSNO) also has the ability to transnitrosylate proteins. It is an NO˙ reservoir and a long-distance signaling molecule. Tyrosine nitration of proteins has been suggested as a biomarker of nitrosative stress as it can lead to either activation or inhibition of target proteins. The exact molecular mechanism(s) by which exogenous and endogenously generated NO (or reactive nitrogen species) modulate the induction of various genes affecting redox homeostasis, are being extensively investigated currently by various research groups. Present review provides an in-depth analysis of the mechanisms by which NO interacts with and modulates the activity of various ROS scavenging enzymes, particularly accompanying ROS generation in plants in response to varied abiotic stress.

  16. Evaluation of scavenging rate constants of DOPA and tyrosine enantiomers against multiple reactive oxygen species and methyl radical as measured with ESR trapping method.

    PubMed

    Sueishi, Yoshimi; Takemoto, Tsubasa

    2015-04-15

    The scavenging rates of DOPA (dl- and l-3-(3,4-dihydroxyphenyl)alanine) and Tyr (tyrosine (dl- and l-3-(4-hydroxyphenyl)alanine)) against five reactive oxygen species (ROS) and methyl radical were measured with the use of electron spin resonance (ESR) spin-trapping method and the scavenging rate constants of DOPA and Tyr were determined. The scavenging rate constants for multiple active species increased in the order of O2(-)scavenging abilities for l-enantiomers and dl-mixtures of DOPA and Tyr were shown. Further, based on the redox potentials, we have suggested that the primary chemical process of antioxidant reactions with O2(-) and (1)O2 can be characterized with the electron transfer of antioxidants (DOPA and Tyr).

  17. Electrochemically reduced water exerts superior reactive oxygen species scavenging activity in HT1080 cells than the equivalent level of hydrogen-dissolved water

    PubMed Central

    Hamasaki, Takeki; Harada, Gakuro; Nakamichi, Noboru; Kabayama, Shigeru; Teruya, Kiichiro; Fugetsu, Bunshi; Gong, Wei; Sakata, Ichiro; Shirahata, Sanetaka

    2017-01-01

    Electrochemically reduced water (ERW) is produced near a cathode during electrolysis and exhibits an alkaline pH, contains richly dissolved hydrogen, and contains a small amount of platinum nanoparticles. ERW has reactive oxygen species (ROS)-scavenging activity and recent studies demonstrated that hydrogen-dissolved water exhibits ROS-scavenging activity. Thus, the antioxidative capacity of ERW is postulated to be dependent on the presence of hydrogen levels; however, there is no report verifying the role of dissolved hydrogen in ERW. In this report, we clarify whether the responsive factor for antioxidative activity in ERW is dissolved hydrogen. The intracellular ROS scavenging activity of ERW and hydrogen-dissolved water was tested by both fluorescent stain method and immuno spin trapping assay. We confirm that ERW possessed electrolysis intensity-dependent intracellular ROS-scavenging activity, and ERW exerts significantly superior ROS-scavenging activity in HT1080 cells than the equivalent level of hydrogen-dissolved water. ERW retained its ROS-scavenging activity after removal of dissolved hydrogen, but lost its activity when autoclaved. An oxygen radical absorbance capacity assay, the 2,2-diphenyl-1-picrylhydrazyl assay and chemiluminescence assay could not detect radical-scavenging activity in both ERW and hydrogen-dissolved water. These results indicate that ERW contains electrolysis-dependent hydrogen and an additional antioxidative factor predicted to be platinum nanoparticles. PMID:28182635

  18. Electrochemically reduced water exerts superior reactive oxygen species scavenging activity in HT1080 cells than the equivalent level of hydrogen-dissolved water.

    PubMed

    Hamasaki, Takeki; Harada, Gakuro; Nakamichi, Noboru; Kabayama, Shigeru; Teruya, Kiichiro; Fugetsu, Bunshi; Gong, Wei; Sakata, Ichiro; Shirahata, Sanetaka

    2017-01-01

    Electrochemically reduced water (ERW) is produced near a cathode during electrolysis and exhibits an alkaline pH, contains richly dissolved hydrogen, and contains a small amount of platinum nanoparticles. ERW has reactive oxygen species (ROS)-scavenging activity and recent studies demonstrated that hydrogen-dissolved water exhibits ROS-scavenging activity. Thus, the antioxidative capacity of ERW is postulated to be dependent on the presence of hydrogen levels; however, there is no report verifying the role of dissolved hydrogen in ERW. In this report, we clarify whether the responsive factor for antioxidative activity in ERW is dissolved hydrogen. The intracellular ROS scavenging activity of ERW and hydrogen-dissolved water was tested by both fluorescent stain method and immuno spin trapping assay. We confirm that ERW possessed electrolysis intensity-dependent intracellular ROS-scavenging activity, and ERW exerts significantly superior ROS-scavenging activity in HT1080 cells than the equivalent level of hydrogen-dissolved water. ERW retained its ROS-scavenging activity after removal of dissolved hydrogen, but lost its activity when autoclaved. An oxygen radical absorbance capacity assay, the 2,2-diphenyl-1-picrylhydrazyl assay and chemiluminescence assay could not detect radical-scavenging activity in both ERW and hydrogen-dissolved water. These results indicate that ERW contains electrolysis-dependent hydrogen and an additional antioxidative factor predicted to be platinum nanoparticles.

  19. Pharmacokinetics and preventive effects of platinum nanoparticles as reactive oxygen species scavengers on hepatic ischemia/reperfusion injury in mice.

    PubMed

    Katsumi, Hidemasa; Fukui, Kentaro; Sato, Kanako; Maruyama, Shoko; Yamashita, Shugo; Mizumoto, Erika; Kusamori, Kosuke; Oyama, Munetaka; Sano, Masataka; Sakane, Toshiyasu; Yamamoto, Akira

    2014-05-01

    Reactive oxygen species (ROS) are involved in the pathophysiology of ischemia/reperfusion injury. To protect mouse hepatocytes from ischemia/reperfusion injury, we prepared two different sizes of citric acid-protected platinum nanoparticles (Pt-NPs), which exhibited ROS-scavenging activities and selective delivery to a specific type of liver cell. Small Pt-NPs (30 nm) reduced the superoxide anion, hydrogen peroxide, and hydroxyl radical levels in solution to a greater extent than did large Pt-NPs (106 nm). Large and small Pt-NPs predominantly accumulated in hepatic nonparenchymal cells after intravenous injection into mice. In a mouse model of ischemia/reperfusion injury, in which hepatic injury was induced by occluding the portal vein for 15 min followed by 6 h reperfusion, the increase in plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities was inhibited by a bolus intravenous injection of either large or small Pt-NPs. However, small Pt-NPs inhibited the increase in these markers of hepatic injury to a greater extent than did large Pt-NPs. These results indicate that Pt-NPs can be used to prevent hepatic ischemia/reperfusion injury. To our knowledge, this is the first report demonstrating the pharmacokinetics and efficacy of Pt-NPs to prevent hepatic ischemia/reperfusion injury.

  20. Production and Scavenging of Reactive Oxygen Species and Redox Signaling during Leaf and Flower Senescence: Similar But Different1[OPEN

    PubMed Central

    2016-01-01

    Reactive oxygen species (ROS) play a key role in the regulation of many developmental processes, including senescence, and in plant responses to biotic and abiotic stresses. Several mechanisms of ROS generation and scavenging are similar, but others differ between senescing leaves and petals, despite these organs sharing a common evolutionary origin. Photosynthesis-derived ROS, nutrient remobilization, and reversibility of senescence are necessarily distinct features of the progression of senescence in the two organs. Furthermore, recent studies have revealed specific redox signaling processes that act in concert with phytohormones and transcription factors to regulate senescence-associated genes in leaves and petals. Here, we review some of the recent advances in our understanding of the mechanisms underpinning the production and elimination of ROS in these two organs. We focus on unveiling common and differential aspects of redox signaling in leaf and petal senescence, with the aim of linking physiological, biochemical, and molecular processes. We conclude that the spatiotemporal impact of ROS in senescing tissues differs between leaves and flowers, mainly due to the specific functionalities of these organs. PMID:27208233

  1. Effects of scavengers of reactive oxygen and radical species on cell survival following photodynamic treatment in vitro: comparison to ionizing radiation

    SciTech Connect

    Henderson, B.W.; Miller, A.C.

    1986-11-01

    The effects of various scavengers of reactive oxygen and/or radical species on cell survival in vitro of EMT6 and CHO cells following photodynamic therapy (PDT) or gamma irradiation were compared. None of the agents used exhibited major direct cytotoxicity. Likewise, none interfered with cellular porphyrin uptake, and none except tryptophan altered singlet oxygen production during porphyrin illumination. The radioprotector cysteamine (MEA) was equally effective in reducing cell damage in both modalities. In part, this protection seems to have been induced by oxygen consumption in the system due to MEA autoxidation under formation of H/sub 2/O/sub 2/. The addition of catalase, which prevents H/sub 2/O/sub 2/ buildup, reduced the effect of MEA to the same extent in both treatments. Whether the remaining protection was due to MEA's radical-reducing action or some remaining oxygen limitation is unclear. The protective action of MEA was not mediated by a doubling of cellular glutathione levels, since addition of buthionine sulfoximine, which prevented glutathione increase, did not diminish the observed MEA protection. The hydroxyl radical scavenger mannitol also afforded protection in both, but it was approximately twice as effective in gamma irradiation as in PDT. This is consistent with the predominant role of OH radicals in ionizing radiation damage and their presumed minor involvement in PDT damage. Superoxide dismutase, a scavenger of O/sub 2/, acted as a radiation protector but was not significantly effective in PDT. Catalase, which scavenges H/sub 2/O/sub 2/, was ineffective in both modalities. Tryptophan, an efficient singlet oxygen scavenger, reduced cell death through PDT by several orders of magnitude while being totally ineffective in gamma irradiation. These data reaffirm the predominant role of 1O2 in the photodynamic cell killing but also indicate some involvement of free radical species.

  2. Structure of dihydrochalcones and related derivatives and their scavenging and antioxidant activity against oxygen and nitrogen radical species.

    PubMed

    Bentes, Alexandre L A; Borges, Rosivaldo S; Monteiro, Waldinei R; de Macedo, Luiz G M; Alves, Cláudio N

    2011-02-21

    Quantum mechanical calculations at B3LYP/6-31G** level of theory were employed to obtain energy (E), ionization potential (IP), bond dissociation enthalpy (O-H BDE) and stabilization energies (DE(iso)) in order to infer the scavenging activity of dihydrochalcones (DHC) and structurally related compounds. Spin density calculations were also performed for the proposed antioxidant activity mechanism of 2,4,6-trihydroxyacetophenone (2,4,6-THA). The unpaired electron formed by the hydrogen abstraction from the phenolic hydroxyl group of 2,4,6-THA is localized on the phenolic oxygen at 2, 6, and 4 positions, the C₃ and C₆ carbon atoms at ortho positions, and the C₅ carbon atom at para position. The lowest phenolic oxygen contribution corresponded to the highest scavenging activity value. It was found that antioxidant activity depends on the presence of a hydroxyl at the C2 and C4 positions and that there is a correlation between IP and O-H BDE and peroxynitrite scavenging activity and lipid peroxidation. These results identified the pharmacophore group for DHC.

  3. Antioxidant effects of the ethanol extract from flower of Camellia japonica via scavenging of reactive oxygen species and induction of antioxidant enzymes.

    PubMed

    Piao, Mei Jing; Yoo, Eun Sook; Koh, Young Sang; Kang, Hee Kyoung; Kim, Junoh; Kim, Yong Jin; Kang, Hak Hee; Hyun, Jin Won

    2011-01-01

    The aim of this study was to investigate the antioxidant properties of the ethanol extract of the flower of Camellia japonica (Camellia extract). Camellia extract exhibited 1,1-diphenyl-2-picrylhydrazyl radical and intracellular reactive oxygen species (ROS) scavenging activity in human HaCaT keratinocytes. In addition, Camellia extract scavenged superoxide anion generated by xanthine/xanthine oxidase and hydroxyl radical generated by the Fenton reaction (FeSO(4) + H(2)O(2)) in a cell-free system, which was detected by electron spin resonance spectrometry. Furthermore, Camellia extract increased the protein expressions and activity of cellular antioxidant enzymes, such as superoxide dismutase, catalase and glutathione peroxidase. These results suggest that Camellia extract exhibits antioxidant properties by scavenging ROS and enhancing antioxidant enzymes. Camellia extract contained quercetin, quercetin-3-O-glucoside, quercitrin and kaempferol, which are antioxidant compounds.

  4. Effect of scavengers of active oxygen species on cell damage caused in CHO-K1 cells by phenylhydroquinone, an o-phenylphenol metabolite.

    PubMed

    Tayama, S; Nakagawa, Y

    1994-07-01

    Phenylhydroquinone (PHQ), a metabolite of o-phenylphenol (OPP), is easily autoxidized to phenylbenzoquinone (PBQ) via the semiquinone (phenylsemiquinone, PSQ) with concomitant production of superoxide anion radicals (O2-.). We have used scavengers of active oxygen species to examine whether or not O2-. produced during oxidation of PHQ is related to cell damage in CHO-K1 cells. PHQ at 10 micrograms/ml (3-h treatment) induced sister-chromatid exchange (SCE), endoreduplication (ERD) and cell-cycle delay in CHO-K1 cells. These effects were inhibited by catalase (280 U/ml), a scavenger of hydrogen peroxide (H2O2), as well as by the reductants, ascorbate (3 mM) and GSH (1 mM). Mannitol (50 mM), a scavenger of hydroxyl radical (OH.), was ineffective and superoxide dismutase (SOD, 150 U/ml), a scavenger of O2-., or SOD plus catalase rather intensified the toxicity as did aminotriazole (20 mM), an inhibitor of catalase. Analyses of incubation solutions by HPLC showed that the extent of cell damage is correlated with PHQ loss; catalase suppressed PHQ loss, whereas SOD promoted it. The correlation was more clearly seen in the time courses of cell death and PHQ loss during incubation of PHQ with each of the scavengers of active oxygen species. These results show that neither O2-. nor OH. participates in the cell damage, but rather H2O2 generated via dismutation of O2-. may participate, probably by accelerating the autoxidation of PHQ and thus causing an increase in the production of toxic intermediates. In fact, conversion of PHQ to PBQ, a reactive product, was demonstrated during incubation with PHQ in phosphate-buffered saline by following the changes in UV-visible spectra of PHQ. Inclusion of H2O2 (0.2 or 1 mM) in the incubation mixture accelerated the PHQ loss. The present results can be explained in terms of the autoxidation mechanism of hydroquinone proposed by O'Brien (1991). Different from the results in the absence of S9 mix, the cell damage induced by 50 micrograms

  5. Kinetic Modeling Reveals the Roles of Reactive Oxygen Species Scavenging and DNA Repair Processes in Shaping the Dose-Response Curve of KBrO₃-Induced DNA Damage.

    PubMed

    Spassova, Maria A; Miller, David J; Nikolov, Alexander S

    2015-01-01

    We have developed a kinetic model to investigate how DNA repair processes and scavengers of reactive oxygen species (ROS) can affect the dose-response shape of prooxidant induced DNA damage. We used as an example chemical KBrO3 which is activated by glutathione and forms reactive intermediates that directly interact with DNA to form 8-hydroxy-2-deoxyguanosine DNA adducts (8-OH-dG). The single strand breaks (SSB) that can result from failed base excision repair of these adducts were considered as an effect downstream from 8-OH-dG. We previously demonstrated that, in the presence of effective base excision repair, 8-OH-dG can exhibit threshold-like dose-response dependence, while the downstream SSB can still exhibit a linear dose-response. Here we demonstrate that this result holds for a variety of conditions, including low levels of GSH, the presence of additional SSB repair mechanisms, or a scavenger. It has been shown that melatonin, a terminal scavenger, inhibits KBrO3-caused oxidative damage. Our modeling revealed that sustained exposure to KBrO3 can lead to fast scavenger exhaustion, in which case the dose-response shapes for both endpoints are not substantially affected. The results are important to consider when forming conclusions on a chemical's toxicity dose dependence based on the dose-response of early genotoxic events.

  6. An ethanol extract derived from Bonnemaisonia hamifera scavenges ultraviolet B (UVB) radiation-induced reactive oxygen species and attenuates UVB-induced cell damage in human keratinocytes.

    PubMed

    Piao, Mei Jing; Hyun, Yu Jae; Cho, Suk Ju; Kang, Hee Kyoung; Yoo, Eun Sook; Koh, Young Sang; Lee, Nam Ho; Ko, Mi Hee; Hyun, Jin Won

    2012-12-14

    The present study investigated the photoprotective properties of an ethanol extract derived from the red alga Bonnemaisonia hamifera against ultraviolet B (UVB)-induced cell damage in human HaCaT keratinocytes. The Bonnemaisonia hamifera ethanol extract (BHE) scavenged the superoxide anion generated by the xanthine/xanthine oxidase system and the hydroxyl radical generated by the Fenton reaction (FeSO₄ + H₂O₂), both of which were detected by using electron spin resonance spectrometry. In addition, BHE exhibited scavenging activity against the 1,1-diphenyl-2-picrylhydrazyl radical and intracellular reactive oxygen species (ROS) that were induced by either hydrogen peroxide or UVB radiation. BHE reduced UVB-induced apoptosis, as shown by decreased apoptotic body formation and DNA fragmentation. BHE also attenuated DNA damage and the elevated levels of 8-isoprostane and protein carbonyls resulting from UVB-mediated oxidative stress. Furthermore, BHE absorbed electromagnetic radiation in the UVB range (280-320 nm). These results suggest that BHE protects human HaCaT keratinocytes against UVB-induced oxidative damage by scavenging ROS and absorbing UVB photons, thereby reducing injury to cellular components.

  7. Antioxidant effects of the sarsaparilla via scavenging of reactive oxygen species and induction of antioxidant enzymes in human dermal fibroblasts.

    PubMed

    Park, Gunhyuk; Kim, Tae-mi; Kim, Jeong Hee; Oh, Myung Sook

    2014-07-01

    Ultraviolet (UV) radiation from sunlight causes distinct changes in collagenous skin tissues as a result of the breakdown of collagen, a major component of the extracellular matrix. UV irradiation downregulates reactive oxygen species (ROS)-elimination pathways, thereby promoting the production of ROS, which are implicated in skin aging. Smilax glabra Roxb (sarsaparilla) has been used in folk medicine because of its many effects. However, no study on the protective effects of sarsaparilla root (SR) on human dermal fibroblasts has been reported previously. Here, we investigated the protective effect of SR against oxidative stress in dermal fibroblasts. SR significantly inhibited oxidative damage and skin-aging factor via mitogen-activated protein kinase signaling pathways. Also, SR decreased Ca(2+) and ROS, mitochondrial membrane potential, dysfunction, and increased glutathione, NAD(P)H dehydrogenase and heme oxygenase-1. These results demonstrate that SR can protect dermal fibroblasts against UVB-induced skin aging via antioxidant effects.

  8. Catechol Groups Enable Reactive Oxygen Species Scavenging-Mediated Suppression of PKD-NFkappaB-IL-8 Signaling Pathway by Chlorogenic and Caffeic Acids in Human Intestinal Cells.

    PubMed

    Shin, Hee Soon; Satsu, Hideo; Bae, Min-Jung; Totsuka, Mamoru; Shimizu, Makoto

    2017-02-20

    Chlorogenic acid (CHA) and caffeic acid (CA) are phenolic compounds found in coffee, which inhibit oxidative stress-induced interleukin (IL)-8 production in intestinal epithelial cells, thereby suppressing serious cellular injury and inflammatory intestinal diseases. Therefore, we investigated the anti-inflammatory mechanism of CHA and CA, both of which inhibited hydrogen peroxide (H₂O₂)-induced IL-8 transcriptional activity. They also significantly suppressed nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) transcriptional activity, nuclear translocation of the p65 subunit, and phosphorylation of IκB kinase (IKK). Additionally, upstream of IKK, protein kinase D (PKD) was also suppressed. Finally, we found that they scavenged H₂O₂-induced reactive oxygen species (ROS) and the functional moiety responsible for the anti-inflammatory effects of CHA and CA was the catechol group. Therefore, we conclude that the presence of catechol groups in CHA and CA allows scavenging of intracellular ROS, thereby inhibiting H₂O₂-induced IL-8 production via suppression of PKD-NF-κB signaling in human intestinal epithelial cells.

  9. Silymarin Protects Mouse Liver and Kidney from Thioacetamide Induced Toxicity by Scavenging Reactive Oxygen Species and Activating PI3K-Akt Pathway

    PubMed Central

    Ghosh, Shatadal; Sarkar, Abhijit; Bhattacharyya, Sudip; Sil, Parames C.

    2016-01-01

    Silymarin (SMN) has been shown to possess a wide range of biological and pharmacological effects. Besides, SMN has antioxidant and free radical scavenging activities. Thioacetamide (TAA) is a well-documented liver toxin that requires oxidative bioactivation to elicit its hepatotoxic effect which ultimately modifies amine-lipids and proteins. Our study has been designed in a TAA exposed mouse model to investigate whether SMN could protect TAA-induced oxidative stress mediated hepatic and renal damage. Results suggest that TAA generated reactive oxygen species (ROS), caused oxidative stress and induced apoptosis in the liver and kidney cells via JNK as well as PKC and MAPKs signaling. All these detrimental effects of TAA could, however, be suppressed by SMN which not only scavenged ROS but also induced PI3K-Akt cell survival pathway in the liver and prevented apoptotic pathways in both the organs. Histological studies, collagen staining and DNA fragmentation analysis also supported our results. Combining, we say that SMN possess beneficial role against TAA mediated hepatic and renal pathophysiology. PMID:28018219

  10. Catechol Groups Enable Reactive Oxygen Species Scavenging-Mediated Suppression of PKD-NFkappaB-IL-8 Signaling Pathway by Chlorogenic and Caffeic Acids in Human Intestinal Cells

    PubMed Central

    Shin, Hee Soon; Satsu, Hideo; Bae, Min-Jung; Totsuka, Mamoru; Shimizu, Makoto

    2017-01-01

    Chlorogenic acid (CHA) and caffeic acid (CA) are phenolic compounds found in coffee, which inhibit oxidative stress-induced interleukin (IL)-8 production in intestinal epithelial cells, thereby suppressing serious cellular injury and inflammatory intestinal diseases. Therefore, we investigated the anti-inflammatory mechanism of CHA and CA, both of which inhibited hydrogen peroxide (H2O2)-induced IL-8 transcriptional activity. They also significantly suppressed nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) transcriptional activity, nuclear translocation of the p65 subunit, and phosphorylation of IκB kinase (IKK). Additionally, upstream of IKK, protein kinase D (PKD) was also suppressed. Finally, we found that they scavenged H2O2-induced reactive oxygen species (ROS) and the functional moiety responsible for the anti-inflammatory effects of CHA and CA was the catechol group. Therefore, we conclude that the presence of catechol groups in CHA and CA allows scavenging of intracellular ROS, thereby inhibiting H2O2-induced IL-8 production via suppression of PKD-NF-κB signaling in human intestinal epithelial cells. PMID:28230729

  11. Different Reactive Oxygen Species Scavenging Properties of Flavonoids Determine Their Abilities to Extend the Shelf Life of Tomato1[OPEN

    PubMed Central

    Zhang, Yang; De Stefano, Rosalba; Robine, Marie; Butelli, Eugenio; Bulling, Katharina; Hill, Lionel; Rejzek, Martin; Martin, Cathie; Schoonbeek, Henk-jan

    2015-01-01

    The shelf life of tomato (Solanum lycopersicum) fruit is determined by the processes of overripening and susceptibility to pathogens. Postharvest shelf life is one of the most important traits for commercially grown tomatoes. We compared the shelf life of tomato fruit that accumulate different flavonoids and found that delayed overripening is associated with increased total antioxidant capacity caused by the accumulation of flavonoids in the fruit. However, reduced susceptibility to Botrytis cinerea, a major postharvest fungal pathogen of tomato, is conferred by specific flavonoids only. We demonstrate an association between flavonoid structure, selective scavenging ability for different free radicals, and reduced susceptibility to B. cinerea. Our study provides mechanistic insight into how flavonoids influence the shelf life, information that could be used to improve the shelf life of tomato and, potentially, other soft fruit. PMID:26082399

  12. Different Reactive Oxygen Species Scavenging Properties of Flavonoids Determine Their Abilities to Extend the Shelf Life of Tomato.

    PubMed

    Zhang, Yang; De Stefano, Rosalba; Robine, Marie; Butelli, Eugenio; Bulling, Katharina; Hill, Lionel; Rejzek, Martin; Martin, Cathie; Schoonbeek, Henk-jan

    2015-11-01

    The shelf life of tomato (Solanum lycopersicum) fruit is determined by the processes of overripening and susceptibility to pathogens. Postharvest shelf life is one of the most important traits for commercially grown tomatoes. We compared the shelf life of tomato fruit that accumulate different flavonoids and found that delayed overripening is associated with increased total antioxidant capacity caused by the accumulation of flavonoids in the fruit. However, reduced susceptibility to Botrytis cinerea, a major postharvest fungal pathogen of tomato, is conferred by specific flavonoids only. We demonstrate an association between flavonoid structure, selective scavenging ability for different free radicals, and reduced susceptibility to B. cinerea. Our study provides mechanistic insight into how flavonoids influence the shelf life, information that could be used to improve the shelf life of tomato and, potentially, other soft fruit.

  13. Scavenging of reactive oxygen species in apoplastic and symplastic areas of rolled leaves in Ctenanthe setosa under drought stress.

    PubMed

    Saruhan, Neslihan; Terzi, Rabiye; Sağlam, Aykut; Kadioğlu, Asim

    2010-09-01

    The correspondence among apoplastic and symplastic antioxidant status, stomatal conductance and water potential was investigated during leaf rolling in Ctenanthe setosa (Rosc.) Eichler (Marantaceae) under drought stress. Apoplastic and symplastic extractions of leaf and petiole were performed at different visual leaf rolling scores from 1 to 4 (1 is unrolled, 4 is tightly rolled and the others are intermediate form). In the leaf symplast, the highest changes were found in catalase (CAT) and guaiacol peroxidase (GPX) activities when compared to score 1 during leaf rolling. No significant change was observed in superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities in the symplast of leaf during the rolling. The same phenomenon was also present in the symplast of petiole except APX activity. In the leaf apoplast, the highest increase occurred in APX and GPX activities, whilst a slight increase in CAT and SOD activities. In the apoplast of petiole, the highest increment was found only in GPX activity, while there were small increases in SOD, APX and CAT activities. Hydrogen peroxide content increased up to score 3 in the apoplast and symplast of leaf and petiole but then slightly decreased. Also, superoxide production increased in the leaf and petiole apoplast but its quantity in the apoplast was much more than that of the symplast. On the other hand, NAD(P)H oxidase activity increased in the leaf but no change was observed in the petiole. In conclusion, as a result of water deficit during leaf rolling antioxidant enzymes are induced to scavenging of ROS produced in symplast and apoplast.

  14. Effect of Laurus nobilis L. Essential Oil and its Main Components on α-glucosidase and Reactive Oxygen Species Scavenging Activity

    PubMed Central

    Sahin Basak, Serap; Candan, Ferda

    2013-01-01

    The present study was designed to determine the effects of the essential oil of Laurus nobilis L. (Lauraceae) and its three main components on α-glucosidase and reactive oxygen species scavenging activity. The chemical composition of the essential oil from Laurus nobilis L. leaves was analyzed by GC/GC-MS and resulted in the identification of 29 compounds, representing 99.18% of the total oil. 1,8-cineole (68.82%), 1-(S)-α-pinene (6.94%), and R-(+)- limonene (3.04%) were determined to be the main components. The antioxidant features of the essential oil and its three main components were evaluated using inhibition of 2,2-diphenyl-1- picrylhydrazyl, hydroxyl, and superoxide radicals, inhibition of hydrogen peroxide and lipid peroxidation assays. The results show that the DPPH, hydroxyl, and superoxide radical as well as hydrogen peroxide scavenging activities of the essential oil are greater than the positive controls and the three main components of the oil when tested independently. The inhibition of lipid peroxidation by the oil occurred less frequently than with 1,8-cineole and R-(+)- limonene alone, but the effects were more pronounced than those seen with 1-(S)-α-pinene and the positive controls. An α-glucosidase inhibition assay was applied to evaluate the in-vitro antidiabetic activity of the essential oil. IC50-values were obtained for laurel essential oil, 1, 8-cineole, 1-(S)-α-pinene, and R-(+)-limonene: 1.748 μL/mL, 1.118 μL/mL, 1.420 μL/mL and 1.300 μL/mL, respectively. We also found that laurel essential oil and 1, 8-cineole inhibited the α-glucosidase competitively while 1-(S)-α-pinene and R-(+)-limonene were uncompetitive inhibitors. PMID:24250611

  15. An Arabidopsis Zinc Finger Protein Increases Abiotic Stress Tolerance by Regulating Sodium and Potassium Homeostasis, Reactive Oxygen Species Scavenging and Osmotic Potential

    PubMed Central

    Zang, Dandan; Li, Hongyan; Xu, Hongyun; Zhang, Wenhui; Zhang, Yiming; Shi, Xinxin; Wang, Yucheng

    2016-01-01

    Plant zinc finger proteins (ZFPs) comprise a large protein family and they are mainly involved in abiotic stress tolerance. Although Arabidopsis RING/FYVE/PHD ZFP At5g62460 (AtRZFP) is found to bind to zinc, whether it is involved in abiotic stress tolerance is still unknown. In the present study, we characterized the roles of AtRZFP in response to abiotic stresses. The expression of AtRZFP was induced significantly by salt and osmotic stress. AtRZFP positively mediates tolerance to salt and osmotic stress. Additionally, compared with wild-type Arabidopsis plants, plants overexpressing AtRZFP showed reduced reactive oxygen species (ROSs) accumulation, enhanced superoxide dismutase and peroxidase activity, increased soluble sugars and proline contents, reduced K+ loss, decreased Na+ accumulation, stomatal aperture and the water loss rate. Conversely, AtRZFP knockout plants displayed the opposite physiological changes when exposed to salt or osmotic stress conditions. These data suggested that AtRZFP enhances salt and osmotic tolerance through a series of physiological processes, including enhanced ROSs scavenging, maintaining Na+ and K+ homeostasis, controlling the stomatal aperture to reduce the water loss rate, and accumulating soluble sugars and proline to adjust the osmotic potential. PMID:27605931

  16. Resistance-breaking population of Meloidogyne incognita utilizes plant peroxidase to scavenge reactive oxygen species, thereby promoting parasitism on tomato carrying Mi-1 gene.

    PubMed

    Guan, Tinglong; Shen, Jinhua; Fa, Yang; Su, Yishi; Wang, Xuan; Li, Hongmei

    2017-01-01

    Resistance conferred by the Mi-1 gene from Solanum peruvianum is effective and widely used for controlling root-knot nematodes (RKNs, Meloidogyne spp.). However, breakdown of resistance by RKNs seriously threatens the durable application of the resistance resource. Here, a resistance-breaking population of M. incognita was selected from an avirulent population by continuously inoculating on Mi-1-carrying tomato. Histological observations showed the resistance-breaking population would not induce hypersensitive response (HR) when infecting Mi-1-carrying tomato, while avirulent population did. A total of 308 differentially expressed genes (DEGs) were identified from Mi-1-carrying tomato upon infection with resistance-breaking versus avirulent populations by RNA-seq. The expression patterns of 23 selected DEGs were validated by quantitative real-time PCR (qRT-PCR). Subsequently, seven out of nine highly up-regulated DEGs were successfully knocked down in Mi-1-carrying tomato by tobacco rattle virus (TRV) mediated RNAi. The TRV line targeting a peroxidase gene showed a much higher magnitude of reactive oxygen species (ROS) and distinct reduction of pathogenicity upon infection of the resistance-breaking population compared with that of TRV::gfp line. Our results suggested that plant peroxidase might be exploited by resistance-breaking population of M. incognita to scavenge ROS, so as to overcome Mi-1-mediated resistance.

  17. Scavenging dissolved oxygen via acoustic droplet vaporization.

    PubMed

    Radhakrishnan, Kirthi; Holland, Christy K; Haworth, Kevin J

    2016-07-01

    Acoustic droplet vaporization (ADV) of perfluorocarbon emulsions has been explored for diagnostic and therapeutic applications. Previous studies have demonstrated that vaporization of a liquid droplet results in a gas microbubble with a diameter 5-6 times larger than the initial droplet diameter. The expansion factor can increase to a factor of 10 in gassy fluids as a result of air diffusing from the surrounding fluid into the microbubble. This study investigates the potential of this process to serve as an ultrasound-mediated gas scavenging technology. Perfluoropentane droplets diluted in phosphate-buffered saline (PBS) were insonified by a 2 MHz transducer at peak rarefactional pressures lower than and greater than the ADV pressure amplitude threshold in an in vitro flow phantom. The change in dissolved oxygen (DO) of the PBS before and after ADV was measured. A numerical model of gas scavenging, based on conservation of mass and equal partial pressures of gases at equilibrium, was developed. At insonation pressures exceeding the ADV threshold, the DO of air-saturated PBS decreased with increasing insonation pressures, dropping as low as 25% of air saturation within 20s. The decrease in DO of the PBS during ADV was dependent on the volumetric size distribution of the droplets and the fraction of droplets transitioned during ultrasound exposure. Numerically predicted changes in DO from the model agreed with the experimentally measured DO, indicating that concentration gradients can explain this phenomenon. Using computationally modified droplet size distributions that would be suitable for in vivo applications, the DO of the PBS was found to decrease with increasing concentrations. This study demonstrates that ADV can significantly decrease the DO in an aqueous fluid, which may have direct therapeutic applications and should be considered for ADV-based diagnostic or therapeutic applications.

  18. Kinetic Modeling Reveals the Roles of Reactive Oxygen Species Scavenging and DNA Repair Processes in Shaping the Dose-Response Curve of KBrO3-Induced DNA Damage

    PubMed Central

    Spassova, Maria A.; Miller, David J.; Nikolov, Alexander S.

    2015-01-01

    We have developed a kinetic model to investigate how DNA repair processes and scavengers of reactive oxygen species (ROS) can affect the dose-response shape of prooxidant induced DNA damage. We used as an example chemical KBrO3 which is activated by glutathione and forms reactive intermediates that directly interact with DNA to form 8-hydroxy-2-deoxyguanosine DNA adducts (8-OH-dG). The single strand breaks (SSB) that can result from failed base excision repair of these adducts were considered as an effect downstream from 8-OH-dG. We previously demonstrated that, in the presence of effective base excision repair, 8-OH-dG can exhibit threshold-like dose-response dependence, while the downstream SSB can still exhibit a linear dose-response. Here we demonstrate that this result holds for a variety of conditions, including low levels of GSH, the presence of additional SSB repair mechanisms, or a scavenger. It has been shown that melatonin, a terminal scavenger, inhibits KBrO3-caused oxidative damage. Our modeling revealed that sustained exposure to KBrO3 can lead to fast scavenger exhaustion, in which case the dose-response shapes for both endpoints are not substantially affected. The results are important to consider when forming conclusions on a chemical's toxicity dose dependence based on the dose-response of early genotoxic events. PMID:26448819

  19. DNA cleavage activity of Fe(II)N4Py under photo irradiation in the presence of 1,8-naphthalimide and 9-aminoacridine: unexpected effects of reactive oxygen species scavengers.

    PubMed

    Li, Qian; Browne, Wesley R; Roelfes, Gerard

    2011-09-05

    The DNA cleavage activity of the iron(II) complex of the ligand N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine (N4Py) was investigated in the presence of the chromophores 1,8-naphthalimide (NI) and 9-aminoacridine (AA) under photo irradiation at 355 and 400.8 nm and compared to the activity of the complex without the chromophores. Whereas in most cases no synergistic effect of the added chromophores on DNA cleavage efficiency was observed, it was found that for Fe(II)N4Py, in combination with NI under irradiation at 355 nm, the DNA cleavage activity was increased. Surprisingly, it was found that the addition of reactive oxygen species (ROS) scavengers gave rise to significantly increased DNA cleavage efficiency, which is a highly counterintuitive observation since ROS are needed to achieve DNA cleavage. A hypothesis is put forward to explain, at least partly, these results. It is proposed that the addition of scavengers inhibits quenching of (3)NI*, thus making photo-induced electron transfer between (3)NI* and Fe(III)N4Py more efficient. This results in reduction of Fe(III)N4Py to Fe(II)N4Py, which can then react with ROS giving rise to DNA cleavage. Hence the role of the scavengers is to maintain a close to optimal concentration of ROS. The present study serves as an illustration of the care that needs to be exercised in interpreting the results of experiments using standard ROS scavengers, since especially in complex systems such as presented here they can give rise to unexpected phenomena. In the presence of 1,8-naphthalimide or 9-aminoacridine, ROS scavengers can increase the DNA cleavage efficiency of Fe(II)N4Py complex under photo irradiation.

  20. Sodium cromoglycate and doxantrazole are oxygen radical scavengers.

    PubMed

    Sadeghi-Hashjin, G; Nijkamp, F P; Henricks, P A J; Folkerts, G

    2002-10-01

    The effects of two mast cell stabilisers, sodium cromoglycate (SCG) and doxantrazole, on the formation of reactive oxygen species (ROS) were studied. Guinea-pig alveolar macrophages (AMs) generated lucigenin-dependent chemiluminescence (LDCL). This was increased when the cells were stimulated by phorbol myristate acetate (PMA) or zymosan (by 133% and 464%, respectively, in total LDCL over 60 min). SCG decreased PMA-induced LDCL at higher concentrations (10 mM, by 55%) than doxantrazole (1 mM, by 75%). SCG decreased radical production by AMs in response to zymosan in a concentration-dependent manner by < or = 72%. Doxantrazole (0.1-1 mM) diminished total LDCL by 30-80%. In addition, glucose oxidase led to LDCL generation when incubated with glucose in a cell-free medium. This was inhibited by 47-83% in the presence of SCG or doxantrazole. SCG and doxantrazole inhibited the hydrogen peroxide- and peroxynitrite-induced LDCL by < or = 92%. Moreover, these drugs slightly increased the survival rate of the AMs. It is concluded that doxantrazole- and sodium cromoglycate-inhibited lucigenin-dependent chemiluminescence production by guinea-pig alveolar macrophages is due to a direct scavenging effect on reactive oxygen species. Doxantrazole is approximately 10-times more potent. Mast cell stabilisers may be effective in allergic asthma not only by preventing the allergen-induced mediator release, but also by preventing radical-induced lung damage.

  1. Flavanoid-rich fraction from Sageretia theezans leaves scavenges reactive oxygen radical species and increases the resistance of low-density lipoprotein to oxidation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To explore their bioactive fractions, S. theezans leaves were extracted 2 with 60% acetone and then fractionated sequentially with hexane, ethyl acetate, and water. ROS (HOCl, ONOO-, and O2 deg -) scavenging activity, ORAC value and total phenolic content of each fraction were investigated. The ethy...

  2. The role of vasoactive intestinal peptide in scavenging singlet oxygen

    SciTech Connect

    Misra, B.R.; Misra, H.P. )

    1990-02-26

    The neuropeptide vasoactive intestinal peptide (VIP), a highly basic 28 amino acid peptide, has a widespread distribution in the body. The functional specificity of this peptide not only includes its potent vasodilatory activity, but also its role in protecting lungs against acute injury, in preventing T-lymphocyte proliferation and in modulating immune function. The purpose of this study was to examine the possible antioxidant properties of VIP. The authors found that VIP up to 50 {mu}g/ml had no inhibitory effect on its reduction of cytochrome C by xanthine and xanthine oxidase, indicating that the peptide does not have significant O{sub 2} scavenging ability. However, VIP was found to inhibit, in a dose-dependent manner, the {sup 1}O{sub 2} dependent 2, 2, 6, 6 tetramethyl piperidine oxide (TEMPO) formation. {sup 1}O{sub 2} was produced by rose benzal photosensitizing system and was detected as TEMP-{sup 1}O{sub 2} adduct (TEMPO) by electron paramagnetic resonance (EPR) spectroscopic technique. The formation of TEMPO signal was strongly inhibited by {beta}-carotene, histidine as well as azide, but not by superoxide dismutase (48 {mu}g/ml), catalase (20 {mu}g/ml) and mannitol (6mM), indicating that TEMPO signal was a TEMP-{sup 1}O{sub 2} adduct. These results indicate that VIP has potent antioxidant activity and may serve as a singlet O{sub 2} scavenger, thus it may modulate the oxidative tissue injury caused by this reactive oxygen species.

  3. Fisetin attenuates hydrogen peroxide-induced cell damage by scavenging reactive oxygen species and activating protective functions of cellular glutathione system.

    PubMed

    Kang, Kyoung Ah; Piao, Mei Jing; Kim, Ki Cheon; Cha, Ji Won; Zheng, Jian; Yao, Cheng Wen; Chae, Sungwook; Hyun, Jin Won

    2014-01-01

    Hydrogen peroxide (H2O2) can induce cell damage by generating reactive oxygen species (ROS), resulting in DNA damage and cell death. The aim of this study is to elucidate the protective effects of fisetin (3,7,3',4',-tetrahydroxy flavone) against H2O2-induced cell damage. Fisetin reduced the level of superoxide anion, hydroxyl radical in cell free system, and intracellular ROS generated by H2O2. Moreover, fisetin protected against H2O2-induced membrane lipid peroxidation, cellular DNA damage, and protein carbonylation, which are the primary cellular outcomes of H2O2 treatment. Furthermore, fisetin increased the level of reduced glutathione (GSH) and expression of glutamate-cysteine ligase catalytic subunit, which is decreased by H2O2. Conversely, a GSH inhibitor abolished the cytoprotective effect of fisetin against H2O2-induced cells damage. Taken together, our results suggest that fisetin protects against H2O2-induced cell damage by inhibiting ROS generation, thereby maintaining the protective role of the cellular GSH system.

  4. Winery by-products: extraction optimization, phenolic composition and cytotoxic evaluation to act as a new source of scavenging of reactive oxygen species.

    PubMed

    Melo, Priscilla Siqueira; Massarioli, Adna Prado; Denny, Carina; dos Santos, Luciana Ferracini; Franchin, Marcelo; Pereira, Giuliano Elias; Vieira, Thais Maria Ferreira de Souza; Rosalen, Pedro Luiz; de Alencar, Severino Matias

    2015-08-15

    Nearly 20 million tons of winery by-products, with many biological activities, are discarded each year in the world. The extraction of bioactive compounds from Chenin Blanc, Petit Verdot, and Syrah grape by-products, produced in the semi-arid region in Brazil, was optimized by a Central Composite Rotatable Design. The phenolic compounds profile, antioxidant capacity against synthetic free radicals (DPPH and ABTS), reactive oxygen species (ROS; peroxyl radical, superoxide radical, hypochlorous acid), cytotoxicity assay (MTT) and quantification of TNF-α production in RAW 264.7 cells were conducted. Gallic acid, syringic acid, procyanidins B1 and B2, catechin, epicatechin, epicatechin gallate, quercetin 3-β-d-glucoside, delfinidin 3-glucoside, peonidin 3-O-glucoside, and malvidin 3-glucoside were the main phenolic compounds identified. In general, rachis showed higher antioxidant capacity than pomace extract, especially for Chenin Blanc. All extracts showed low cytotoxicity against RAW 264.7 cells and Petit Verdot pomace suppressed TNF-α liberation in vitro. Therefore, these winery by-products can be considered good sources of bioactive compounds, with great potential for application in the food and pharmaceutical industries.

  5. Reversible oxygen scavenging at room temperature using electrochemically reduced titanium oxide nanotubes

    NASA Astrophysics Data System (ADS)

    Close, Thomas; Tulsyan, Gaurav; Diaz, Carlos A.; Weinstein, Steven J.; Richter, Christiaan

    2015-05-01

    A material capable of rapid, reversible molecular oxygen uptake at room temperature is desirable for gas separation and sensing, for technologies that require oxygen storage and oxygen splitting such as fuel cells (solid-oxide fuel cells in particular) and for catalytic applications that require reduced oxygen species (such as removal of organic pollutants in water and oil-spill remediation). To date, however, the lowest reported temperature for a reversible oxygen uptake material is in the range of 200-300 °C, achieved in the transition metal oxides SrCoOx (ref. 1) and LuFe2O4+x (ref. 2) via thermal cycling. Here, we report rapid and reversible oxygen scavenging by TiO2-x nanotubes at room temperature. The uptake and release of oxygen is accomplished by an electrochemical rather than a standard thermal approach. We measure an oxygen uptake rate as high as 14 mmol O2 g-1 min-1, ˜2,400 times greater than commercial, irreversible oxygen scavengers. Such a fast oxygen uptake at a remarkably low temperature suggests a non-typical mechanistic pathway for the re-oxidation of TiO2-x. Modelling the diffusion of oxygen, we show that a likely pathway involves ‘exceptionally mobile’ interstitial oxygen produced by the oxygen adsorption and decomposition dynamics, recently observed on the surface of anatase.

  6. Rice ASR1 protein with reactive oxygen species scavenging and chaperone-like activities enhances acquired tolerance to abiotic stresses in Saccharomyces cerevisiae.

    PubMed

    Kim, Il-Sup; Kim, Young-Saeng; Yoon, Ho-Sung

    2012-03-01

    Abscisic acid stress ripening (ASR1) protein is a small hydrophilic, low molecular weight, and stress-specific plant protein. The gene coding region of ASR1 protein, which is induced under high salinity in rice (Oryza sativa Ilmi), was cloned into a yeast expression vector pVTU260 and transformed into yeast cells. Heterologous expression of ASR1 protein in transgenic yeast cells improved tolerance to abiotic stresses including hydrogen peroxide (H(2)O(2)), high salinity (NaCl), heat shock, menadione, copper sulfate, sulfuric acid, lactic acid, salicylic acid, and also high concentration of ethanol. In particular, the expression of metabolic enzymes (Fba1p, Pgk1p, Eno2p, Tpi1p, and Adh1p), antioxidant enzyme (Ahp1p), molecular chaperone (Ssb1p), and pyrimidine biosynthesis-related enzyme (Ura1p) was up-regulated in the transgenic yeast cells under oxidative stress when compared with wild-type cells. All of these enzymes contribute to an alleviated redox state to H2O2-induced oxidative stress. In the in vitro assay, the purified ASR1 protein was able to scavenge ROS by converting H(2)O(2) to H(2)O. Taken together, these results suggest that the ASR1 protein could function as an effective ROS scavenger and its expression could enhance acquired tolerance of ROS-induced oxidative stress through induction of various cell rescue proteins in yeast cells.

  7. Isorhamnetin inhibits H₂O₂-induced activation of the intrinsic apoptotic pathway in H9c2 cardiomyocytes through scavenging reactive oxygen species and ERK inactivation.

    PubMed

    Sun, Bing; Sun, Gui-Bo; Xiao, Jing; Chen, Rong-Chang; Wang, Xin; Wu, Ying; Cao, Li; Yang, Zhi-Hong; Sun, Xiao-Bo

    2012-02-01

    As a traditional Chinese medicine, the sea buckthorn (Hippophae rhamnoides L.) has a long history in the treatment of ischemic heart disease and circulatory disorders. However, the active compounds responsible for and the underlying mechanisms of these effects are not fully understood. In this article, isorhamnetin pretreatment counteracted H(2)O(2)-induced apoptotic damage in H9c2 cardiomyocytes. Isorhamnetin did not inhibit the death receptor-dependent or extrinsic apoptotic pathways, as characterized by its absence in both caspase-8 inactivation and tBid downregulation along with unchanged Fas and TNFR1 mRNA levels. Instead, isorhamnetin specifically suppressed the mitochondria-dependent or intrinsic apoptotic pathways, as characterized by inactivation of caspase-9 and -3, maintenance of the mitochondrial membrane potential (ΔΨm), and regulation of a series of Bcl-2 family genes upstream of ΔΨm. The anti-apoptotic effects of isorhamnetin were linked to decreased ROS generation. H(2)O(2) activated ERK and p53, whereas isorhamnetin inhibited their activation. ERK overexpression overrode the isorhamnetin-induced inhibition of the intrinsic apoptotic pathway in H9c2 cardiomyocytes, which indicated that an ERK-dependent pathway was involved. Furthermore, N-acetyl cysteine (a potent ROS scavenger) could attenuate the H(2)O(2)-induced apoptosis. However, PD98059 (an ERK-specific inhibitor) could not effectively antagonize ROS generation, which indicates that ROS may be an upstream inducer of ERK. In conclusion, isorhamnetin inhibits the H(2)O(2)-induced activation of the intrinsic apoptotic pathway via ROS scavenging and ERK inactivation. Therefore, isorhamnetin is a promising reagent for the treatment of ROS-induced cardiomyopathy.

  8. A STRESS-RESPONSIVE NAC1-Regulated Protein Phosphatase Gene Rice Protein Phosphatase18 Modulates Drought and Oxidative Stress Tolerance through Abscisic Acid-Independent Reactive Oxygen Species Scavenging in Rice1[W][OPEN

    PubMed Central

    You, Jun; Zong, Wei; Hu, Honghong; Li, Xianghua; Xiao, Jinghua; Xiong, Lizhong

    2014-01-01

    Plants respond to abiotic stresses through a complexity of signaling pathways, and the dephosphorylation mediated by protein phosphatase (PP) is an important event in this process. We identified a rice (Oryza sativa) PP2C gene, OsPP18, as a STRESS-RESPONSIVE NAC1 (SNAC1)-regulated downstream gene. The ospp18 mutant was more sensitive than wild-type plants to drought stress at both the seedling and panicle development stages. Rice plants with OsPP18 suppressed through artificial microRNA were also hypersensitive to drought stress. Microarray analysis of the mutant revealed that genes encoding reactive oxygen species (ROS) scavenging enzymes were down-regulated in the ospp18 mutant, and the mutant exhibited reduced activities of ROS scavenging enzymes and increased sensitivity to oxidative stresses. Overexpression of OsPP18 in rice led to enhanced osmotic and oxidative stress tolerance. The expression of OsPP18 was induced by drought stress but not induced by abscisic acid (ABA). Although OsPP18 is a typical PP2C with enzymatic activity, it did not interact with SNF1-RELATED PROTEIN KINASE2 protein kinases, which function in ABA signaling. Meanwhile, the expression of ABA-responsive genes was not affected in the ospp18 mutant, and the ABA sensitivities of the ospp18 mutant and OsPP18-overexpressing plants were also not altered. Together, these findings suggest that OsPP18 is a unique PP2C gene that is regulated by SNAC1 and confers drought and oxidative stress tolerance by regulating ROS homeostasis through ABA-independent pathways. PMID:25318938

  9. Bacterial Fucose-Rich Polysaccharide Stabilizes MAPK-Mediated Nrf2/Keap1 Signaling by Directly Scavenging Reactive Oxygen Species during Hydrogen Peroxide-Induced Apoptosis of Human Lung Fibroblast Cells

    PubMed Central

    Roy Chowdhury, Sougata; Sinha, Tridib Kumar; Sen, Ramkrishna; Basak, Ratan Kumar; Adhikari, Basudam; Bhattacharyya, Arindam

    2014-01-01

    Continuous free radical assault upsets cellular homeostasis and dysregulates associated signaling pathways to promote stress-induced cell death. In spite of the continuous development and implementation of effective therapeutic strategies, limitations in treatments for stress-induced toxicities remain. The purpose of the present study was to determine the potential therapeutic efficacy of bacterial fucose polysaccharides against hydrogen peroxide (H2O2)-induced stress in human lung fibroblast (WI38) cells and to understand the associated molecular mechanisms. In two different fermentation processes, Bacillus megaterium RB-05 biosynthesized two non-identical fucose polysaccharides; of these, the polysaccharide having a high-fucose content (∼42%) conferred the maximum free radical scavenging efficiency in vitro. Structural characterizations of the purified polysaccharides were performed using HPLC, GC-MS, and 1H/13C/2D-COSY NMR. H2O2 (300 µM) insult to WI38 cells showed anti-proliferative effects by inducing intracellular reactive oxygen species (ROS) and by disrupting mitochondrial membrane permeability, followed by apoptosis. The polysaccharide (250 µg/mL) attenuated the cell death process by directly scavenging intracellular ROS rather than activating endogenous antioxidant enzymes. This process encompasses inhibition of caspase-9/3/7, a decrease in the ratio of Bax/Bcl2, relocalization of translocated Bax and cytochrome c, upregulation of anti-apoptotic members of the Bcl2 family and a decrease in the phosphorylation of MAPKs (mitogen activated protein kinases). Furthermore, cellular homeostasis was re-established via stabilization of MAPK-mediated Nrf2/Keap1 signaling and transcription of downstream cytoprotective genes. This molecular study uniquely introduces a fucose-rich bacterial polysaccharide as a potential inhibitor of H2O2-induced stress and toxicities. PMID:25412177

  10. Bacterial fucose-rich polysaccharide stabilizes MAPK-mediated Nrf2/Keap1 signaling by directly scavenging reactive oxygen species during hydrogen peroxide-induced apoptosis of human lung fibroblast cells.

    PubMed

    Roy Chowdhury, Sougata; Sengupta, Suman; Biswas, Subir; Sinha, Tridib Kumar; Sen, Ramkrishna; Basak, Ratan Kumar; Adhikari, Basudam; Bhattacharyya, Arindam

    2014-01-01

    Continuous free radical assault upsets cellular homeostasis and dysregulates associated signaling pathways to promote stress-induced cell death. In spite of the continuous development and implementation of effective therapeutic strategies, limitations in treatments for stress-induced toxicities remain. The purpose of the present study was to determine the potential therapeutic efficacy of bacterial fucose polysaccharides against hydrogen peroxide (H2O2)-induced stress in human lung fibroblast (WI38) cells and to understand the associated molecular mechanisms. In two different fermentation processes, Bacillus megaterium RB-05 biosynthesized two non-identical fucose polysaccharides; of these, the polysaccharide having a high-fucose content (∼ 42%) conferred the maximum free radical scavenging efficiency in vitro. Structural characterizations of the purified polysaccharides were performed using HPLC, GC-MS, and (1)H/(13)C/2D-COSY NMR. H2O2 (300 µM) insult to WI38 cells showed anti-proliferative effects by inducing intracellular reactive oxygen species (ROS) and by disrupting mitochondrial membrane permeability, followed by apoptosis. The polysaccharide (250 µg/mL) attenuated the cell death process by directly scavenging intracellular ROS rather than activating endogenous antioxidant enzymes. This process encompasses inhibition of caspase-9/3/7, a decrease in the ratio of Bax/Bcl2, relocalization of translocated Bax and cytochrome c, upregulation of anti-apoptotic members of the Bcl2 family and a decrease in the phosphorylation of MAPKs (mitogen activated protein kinases). Furthermore, cellular homeostasis was re-established via stabilization of MAPK-mediated Nrf2/Keap1 signaling and transcription of downstream cytoprotective genes. This molecular study uniquely introduces a fucose-rich bacterial polysaccharide as a potential inhibitor of H2O2-induced stress and toxicities.

  11. Deferasirox is a powerful NF-κB inhibitor in myelodysplastic cells and in leukemia cell lines acting independently from cell iron deprivation by chelation and reactive oxygen species scavenging

    PubMed Central

    Messa, Emanuela; Carturan, Sonia; Maffè, Chiara; Pautasso, Marisa; Bracco, Enrico; Roetto, Antonella; Messa, Francesca; Arruga, Francesca; Defilippi, Ilaria; Rosso, Valentina; Zanone, Chiara; Rotolo, Antonia; Greco, Elisabetta; Pellegrino, Rosa M.; Alberti, Daniele; Saglio, Giuseppe; Cilloni, Daniela

    2010-01-01

    Background Usefulness of iron chelation therapy in myelodysplastic patients is still under debate but many authors suggest its possible role in improving survival of low-risk myelodysplastic patients. Several reports have described an unexpected effect of iron chelators, such as an improvement in hemoglobin levels, in patients affected by myelodysplastic syndromes. Furthermore, the novel chelator deferasirox induces a similar improvement more rapidly. Nuclear factor-κB is a key regulator of many cellular processes and its impaired activity has been described in different myeloid malignancies including myelodysplastic syndromes. Design and Methods We evaluated deferasirox activity on nuclear factor-κB in myelodysplastic syndromes as a possible mechanism involved in hemoglobin improvement during in vivo treatment. Forty peripheral blood samples collected from myelodysplastic syndrome patients were incubated with 50 μM deferasirox for 18h. Results Nuclear factor-κB activity dramatically decreased in samples showing high basal activity as well as in cell lines, whereas no similar behavior was observed with other iron chelators despite a similar reduction in reactive oxygen species levels. Additionally, ferric hydroxyquinoline incubation did not decrease deferasirox activity in K562 cells suggesting the mechanism of action of the drug is independent from cell iron deprivation by chelation. Finally, incubation with both etoposide and deferasirox induced an increase in K562 apoptotic rate. Conclusions Nuclear factor-κB inhibition by deferasirox is not seen from other chelators and is iron and reactive oxygen species scavenging independent. This could explain the hemoglobin improvement after in vivo treatment, such that our hypothesis needs to be validated in further prospective studies. PMID:20534700

  12. Deuterohemin-AlaHisLys mitigates the symptoms of rats with non-insulin dependent diabetes mellitus by scavenging reactive oxygen species and activating the PI3-K/AKT signal transduction pathway.

    PubMed

    Lei, Liyan; Zhang, Guangji; Li, Pengfei; Zhang, Yuan; Guo, Youming; Zhang, Wenqi; Zhang, Wenbo; Hu, Bing; Wang, Liping

    2014-09-05

    Damage to pancreatic β-cells plays an important role in the development of type 2 diabetes, and oxidative stress is a likely contributor. In the present study, we investigated the effect of deuterohemin-AlaHisLys (DhHP-3), a microperoxidase-11 mimic, on rats with non-insulin dependent diabetes mellitus and examined the action mechanisms of DhHP-3. The induced hyperglycemia, glucose intolerance, and insulin resistance in diabetic rats were associated with increased oxidative stress and damage to pancreatic islets. DhHP-3 (3 mg/kg) ameliorated hyperglycemia and insulin resistance, protected pancreas islet, decreased the content of malondialdehyde, and increased the activity of superoxide dismutase in plasma and pancreatic tissue by reducing ROS levels. Furthermore, DhHP-3 stimulated the proliferation of INS-1 cells and inhibited apoptosis by activating the phosphatidylinositol 3-kinase/protein kinase B (PI3-K/AKT) signaling pathway. Our results demonstrated for the first time that DhHP-3 decreased blood glucose level in rats with non-insulin dependent diabetes mellitus, scavenged reactive oxygen species, activated the PI3-K/AKT signaling pathway, and protected pancreatic β-cells against apoptosis.

  13. The cytoprotective effect of isorhamnetin against oxidative stress is mediated by the upregulation of the Nrf2-dependent HO-1 expression in C2C12 myoblasts through scavenging reactive oxygen species and ERK inactivation.

    PubMed

    Choi, Yung Hyun

    2016-04-01

    This study was designed to confirm the protective effects of isorhamnetin against oxidative stress-induced cellular damage. Our results indicated that isorhamnetin inhibited the hydrogen peroxide (H2O2)-induced growth inhibition and exhibited scavenging activity against the intracellular reactive oxygen species (ROS) in mouse-derived C2C12 myoblasts. Isorhamnetin also significantly attenuated H2O2-induced DNA damage and apoptosis, and increased the levels of the nuclear factor erythroid 2-related factor 2 (Nrf2) and its phosphorylation associated with the induction of heme oxygenase-1 (HO-1). However, the protective effects of isorhamnetin on H2O2-induced ROS and growth inhibition were significantly abolished by an HO-1 competitive inhibitor. Moreover, the potential of isorhamnetin to mediate HO-1 induction and protect against H2O2-mediated growth inhibition was abrogated by transient transfection with Nrf2-specific small interfering RNA. Additionally, isorhamnetin induced the activation of mitogen-activated protein kinases (MAPKs), such as extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 MAPK. However, the specific inhibitor of ERK, but not JNK and p38 MAPK, was able to abolish the HO-1 upregulation and the Nrf2 phosphorylation. Collectively, these results demonstrate that isorhamnetin augments the cellular antioxidant defense capacity by activating the Nrf2/HO-1 pathway involving the activation of the ERK pathway, thus protecting the C2C12 cells from H2O2-induced cytotoxicity.

  14. Free radical scavenging (DPPH) potential in nine Mentha species.

    PubMed

    Ahmad, Nisar; Fazal, Hina; Ahmad, Iftikhar; Abbasi, Bilal Haider

    2012-02-01

    Mentha species are used in every day life in various food items. These species produce valuable secondary metabolites that scavenge toxic free radicals. Toxic free radicals can cause different diseases in the human body. In the present study free radical scavenging potential (1,1-diphenyl-2-picrylhydrazyl scavenging activity) in nine Mentha species were investigated to evaluate and explore new potential sources for natural antioxidants. The activity was performed after different time intervals with incubation period of 30 minutes. The methanolic extracts revealed that significantly higher activity (82%) was observed in Mentha suaveolens, followed by Mentha longifolia (79%), Mentha officinalis (76%) and Mentha piperita, Mentha pulegium, Mentha royleana (75%), respectively. Significantly same activity was observed in Mentha arvensis and Mentha spicata. Lower activity was observed in Mentha citrata (64%). The present study revealed that these species can be used as natural antioxidants.

  15. Bilirubin inhibits the up-regulation of inducible nitric oxide synthase by scavenging reactive oxygen species generated by the toll-like receptor 4-dependent activation of NADPH oxidase.

    PubMed

    Idelman, Gila; Smith, Darcey L H; Zucker, Stephen D

    2015-08-01

    It has been previously shown that bilirubin prevents the up-regulation of inducible nitric oxide synthase (iNOS) in response to LPS. The present study examines whether this effect is exerted through modulation of Toll-Like Receptor-4 (TLR4) signaling. LPS-stimulated iNOS and NADPH oxidase (Nox) activity in RAW 264.7 murine macrophages was assessed by measuring cellular nitrate and superoxide ( [Formula: see text] ) production, respectively. The generation of both nitrate and [Formula: see text] in response to LPS was suppressed by TLR4 inhibitors, indicating that activation of iNOS and Nox is TLR4-dependent. While treatment with superoxide dismutase (SOD) and bilirubin effectively abolished LPS-mediated [Formula: see text] production, hydrogen peroxide and nitrate release were inhibited by bilirubin and PEG-catalase, but not SOD, supporting that iNOS activation is primarily dependent upon intracellular H2O2. LPS treatment increased nuclear translocation of the redox-sensitive transcription factor Hypoxia Inducible Factor-1α (HIF-1α), an effect that was abolished by bilirubin. Cells transfected with murine iNOS reporter constructs in which the HIF-1α-specific hypoxia response element was disrupted exhibited a blunted response to LPS, supporting that HIF-1α mediates Nox-dependent iNOS expression. Bilirubin, but not SOD, blocked the cellular production of interferon-β, while interleukin-6 production remained unaffected. These data support that bilirubin inhibits the TLR4-mediated up-regulation of iNOS by preventing activation of HIF-1α through scavenging of Nox-derived reactive oxygen species. Bilirubin also suppresses interferon-β release via a ROS-independent mechanism. These findings characterize potential mechanisms for the anti-inflammatory effects of bilirubin.

  16. The effects of oxygen scavenging on jet fuel thermal stability

    SciTech Connect

    Heneghan, S.P.; Williams, T.F.; Whitacre, S.; Ervin, J.S.

    1996-10-01

    Preliminary tests with a proposed oxygen scavenger (triphenyl-phosphine, TPP) have been done in closed static and flowing systems to study its effects on the oxidation and the deposit formation of jet fuel. TPP was found to significantly slow the oxidation of hexadecane or jet fuel at some temperatures/concentrations and increase the oxidation rate at other conditions. The additive helped decrease the formation of deposits at higher concentrations (200 mg/l) but not at lower concentrations. No evidence of phosphorous was observed in the deposits that were formed. Gas chomatography combined with mass spectrometry and atomic emission detection showed that TPP produced the expected oxidation product (triphenylphosphineoxide) and an unexpected triphenylphosphine-sulfide. The GC/AED allowed A quantitative analysis of the conversion efficiency of TPP to TPPO upon stressing in a closed system.

  17. Modeling of the Temperature Effect on Oxygen Absorption by Iron-Based Oxygen Scavengers.

    PubMed

    Polyakov, Vladimir A; Miltz, Joseph

    2016-01-01

    A new engineering-oriented model for prediction of the effect of temperature on the kinetics of oxygen absorption by iron-based oxygen scavengers (IOSs) was developed. The model is based on the physicochemical mechanism of the O2 scavenging process by the active component of the IOS (iron powder). The conclusions of this study are: (1) the iron deposits formed on the iron particles are composed of 2 different layers: an inner layer of Fe3 O4 and an outer layer of FeOOH that vanishes with the depletion of oxygen. (2) The model considers the chemical processes in the heterogeneous closed system "Fe-H2 O-NaCl-O2 " and describes the kinetics of oxygen absorption by the powder, depending on the characteristics of the system. (3) The nonlinear ordinary differential equation (ODE) of the O2 absorption kinetics was derived and a simple approximate solution to this ODE was obtained theoretically that is similar to the empirical exponential formula published in the relevant literature. (4) The temperature dependence of the oxygen absorption rate is more complicated than that described by the Arrhenius equation.

  18. Radical scavenging, antioxidant and antimicrobial activities of halophytic species.

    PubMed

    Meot-Duros, Laetitia; Le Floch, Gaëtan; Magné, Christian

    2008-03-05

    For the first time, both antioxidant and antimicrobial activities are simultaneously reported in halophytic plants, particularly on polar fractions. Chloroformic and methanolic extracts of the halophytes Eryngium maritimum L., Crithmum maritimum L. and Cakile maritima Scop. were tested for their antimicrobial activities against 12 bacterial and yeast strains. In addition, radical scavenging and antioxidant activities were assessed, as well as total phenol contents. Only one bacterial strain (Listeria monocytogenes) was not inhibited by plants extracts, and apolar (chloroformic) fractions were generally more active than polar (methanolic) ones. Eryngium maritimum presented the weakest radical scavenging activity (ABTS IC(50)=0.28 mg ml(-1)), as well as the lowest total phenol content (16.4 mg GAE g(-1) DW). However, the three halophytic species had relatively strong total antioxidant activities (from 32.7 to 48.6 mg ascorbate equivalents g (-1) DW). Consequences on the potential use of these plants in food or cosmetic industry are discussed.

  19. DNP and ATP induced alteration in disease development of Phomopsis longanae Chi-inoculated longan fruit by acting on energy status and reactive oxygen species production-scavenging system.

    PubMed

    Lin, Yifen; Chen, Mengyin; Lin, Hetong; Hung, Yen-Con; Lin, Yixiong; Chen, Yihui; Wang, Hui; Shi, John

    2017-08-01

    As compared with P. longanae-inoculated longans, DNP treatment for P. longanae-inoculated longans exhibited higher fruit disease index and pericarp browning index, lower ATP amount and energy charge level, lower activities of SOD, CAT and APX, lower amounts of AsA and GSH, lower levels of DPPH radical scavenging activity and reducing power, higher O2(-) generating rate and MDA amount. However, supply of ATP for P. longanae-inoculated longans showed the contrary effects. These results gave convincing evidence that DNP treatment for accelerating pericarp browning and disease development of harvested longans caused by P. longanae was due to decreases of energy production and ROS scavenging capacity, and increases of O2(-) accumulation and membrane lipid peroxidation. Whereas, supply of ATP for retarding pericarp browning and disease development of harvested longans caused by P. longanae was due to increases of energy production and ROS scavenging capacity, and reductions of O2(-) accumulation and membrane lipid peroxidation.

  20. Role of aluminum as an oxygen-scavenger in zirconium based bulk metallic glasses

    SciTech Connect

    Heinrich, Jochen; Busch, Ralf; Mueller, Frank; Grandthyll, Samuel; Huefner, Stefan

    2012-02-13

    In order to investigate a way to diminish the impact of oxygen onto the critical cooling rate of Zr-based alloys, the bonding chemistry of the elements in Zr-Cu-Ni-Al-Nb-Si bulk metallic glasses with different oxygen contents is studied by x-ray photoelectron spectroscopy. Complementary undercooling experiments lead to continuous-cooling-transformation diagrams for the studied alloys. The experimental results demonstrate that Al not only acts as a scavenger for both absorbed and intrinsic oxygen but the dissolution of its oxide on atomic length scales refrains from heterogeneous nucleation. The combined effect is an enhancement of oxygen tolerance in the investigated alloy.

  1. Singlet Oxygen Scavenging Activity and Cytotoxicity of Essential Oils from Rutaceae

    PubMed Central

    Ao, Yoko; Satoh, Kazue; Shibano, Katsushige; Kawahito, Yukari; Shioda, Seiji

    2008-01-01

    Since we have been exposed to excessive amounts of stressors, aromatherapy for the relaxation has recently become very popular recently. However, there is a problem which responds to light with the essential oil used by aromatherapy. It is generally believed that singlet oxygen is implicated in the pathogenesis of various diseases such as light-induced skin disorders and inflammatory responses. Here we studied whether essential oils can effectively scavenge singlet oxygen upon irradiation, using the electron spin resonance (ESR) method. Green light was used to irradiate twelve essential oils from rutaceae. Among these twelve essential oils, eight were prepared by the expression (or the compression) method (referred to as E oil), and four samples were prepared by the steam distillation method (referred to as SD oil). Five E oils enhanced singlet oxygen production. As these essential oils may be phototoxic, it should be used for their use whit light. Two E oils and three SD oils showed singlet oxygen scavenging activity. These results may suggest that the antioxidant activity of essential oils are judged from their radical scavenging activity. Essential oils, which enhance the singlet oxygen production and show higher cytotoxicity, may contain much of limonene. These results suggest that limonene is involved not only in the enhancement of singlet oxygen production but also in the expression of cytotoxic activity, and that attention has to be necessary for use of blended essential oils. PMID:18648659

  2. Investigation of the oxygen depletion properties of low density polyethylene resins filled with thermally stable oxygen scavengers

    NASA Astrophysics Data System (ADS)

    Yeh, Jen-taut; Cui, Li; Sun, Yan-bin; Xu, Li-ping; Wei, Wei; Tsai, Fang-chang; Jiang, Tao; Zhu, Ping; Huang, Chi-Yuan; Chen, Kan-Nan

    2009-07-01

    The thermal stability, oxygen depletion and tensile properties of low density polyethylene (LDPE) resins filled with ascorbic acid (Vc), sodium ascorbate (SA), iron (Fe) and modified iron (MFe) oxygen scavengers were systematically investigated. Thermogravimetric analysis (TGA) results clearly suggest that the thermal stability of SA powder and L95(SA)5 specimen is significantly better than that of Vc powder and L95(Vc)5 specimen, respectively. The oxygen depletion efficiency of L95(SA)5 is significantly better than that of L95(Vc)5, L95(Fe)5 and L95(MFe)5 specimens, although the virgin SA powders exhibit worse oxygen depletion efficiency than Vc, Fe or MFe powders before melt blending. Moreover, at a fixed weight ratio of Vc (or SA) to MFe of the oxygen scavenger compounds, the oxygen depletion efficiency of L95[SAx(MFe)y]5 series specimens is always significantly better than that of L95[Vcx(MFe)y]5 series specimens. In fact, at weight ratios of Vc/MFe and SA/MFe higher than 3/7 and 5/5, respectively, the residual oxygen concentration values present in the airtight flask of L95[Vcx(MFe)y]5 and L95[SAx(MFe)y]5 series samples at any time are even lower than those of the L95(Vc)5 and L95(SA)5 specimens, respectively. Further tensile experiments show that the tensile properties of the L95[SAx(MFe)y]5 series samples are always higher than those of the corresponding L95[Vcx(MFe)y]5 series samples with the same loadings of oxygen scavenger compounds, respectively. In order to understand these interesting thermal stability, oxygen depletion and tensile properties of these LDPE oxygen-scavenging plastics, scanning electron microscope and energy dispersive X-rays analysis of the compositions on the surfaces of L95[SAx(MFe)y]5 and L95[Vcx(MFe)y]5 series samples were performed. Possible reasons accounting for these interesting properties of these LDPE oxygen-scavenging plastics are proposed.

  3. The use of oxygen scavengers to prevent the transient discolouration of ground beef packaged under controlled, oxygen-depleted atmospheres.

    PubMed

    Gill, C O; McGinnis, J C

    1995-01-01

    Rates of O(2) absorption from air were determined for a type of commercial O(2) scavenger that is formulated for rapid O(2) absorption at chiller temperatures. Rates of O(2) absorption from N(2) atmospheres containing 600 ppm O(2) were determined for trays that each contained 350 g of ground beef. Packs with controlled atmospheres of N(2) that contained ground beef and O(2) scavengers were prepared, to determine the conditions under which the scavengers could prevent the transient discolouration of the meat which arises from its reaction with the residual O(2) initially present in pack atmospheres. The rates of O(2) absorption by individual scavengers varied from the average by ±50%. The rate of O(2) absorption declined with decreasing oxygen concentration, from an average value per scavenger of about 12 ml h(-1) when O(2) concentrations were between 20 and 10%. At O(2) concentrations <1% (10,000 ppm) the rate of O(2) absorption was directly proportioned to the O(2) concentration so that the O(2) concentration in an atmosphere in a gas-impermeable pouch declined exponentially with time. The absorption of O(2) by ground beef was similarly dependent on the O(2) concentration. At 2 °C, the transient discolouration of beef in atmospheres initially containing about 50 ppm O(2) was prevented by the presence of 17.5 scavengers per l of atmosphere. At -15 °C, discolouration was prevented by 5 scavengers per l. The findings indicate that the O(2) concentration in pack atmospheres has to be reduced below 10 ppm within 30 min at 2 °C, or 2 h at -1.5 °C if ground beef is not to transiently discolour. It is unlikely that the required rates of O(2) absorption could be obtained economically with currently available, commercial O(2) scavengers.

  4. ROS Production and Scavenging under Anoxia and Re-Oxygenation in Arabidopsis Cells: A Balance between Redox Signaling and Impairment

    PubMed Central

    Paradiso, Annalisa; Caretto, Sofia; Leone, Antonella; Bove, Anna; Nisi, Rossella; De Gara, Laura

    2016-01-01

    Plants can frequently experience low oxygen concentrations due to environmental factors such as flooding or waterlogging. It has been reported that both anoxia and the transition from anoxia to re-oxygenation determine a strong imbalance in the cellular redox state involving the production of reactive oxygen species (ROS) and nitric oxide (NO). Plant cell cultures can be a suitable system to study the response to oxygen deprivation stress since a close control of physicochemical parameters is available when using bioreactors. For this purpose, Arabidopsis cell suspension cultures grown in a stirred bioreactor were subjected to a severe anoxic stress and analyzed during anoxia and re-oxygenation for alteration in ROS and NO as well as in antioxidant enzymes and metabolites. The results obtained by confocal microscopy showed the dramatic increase of ROS, H2O2, and NO during the anoxic shock. All the ascorbate-glutathione related parameters were altered during anoxia but restored during re-oxygenation. Anoxia also induced a slight but significant increase of α-tocopherol levels measured at the end of the treatment. Overall, the evaluation of cell defenses during anoxia and re-oxygenation in Arabidopsis cell cultures revealed that the immediate response involving the overproduction of reactive species activated the antioxidant machinery including ascorbate-glutathione system, α-tocopherol and the ROS-scavenging enzymes ascorbate peroxidase, catalase, and peroxidase making cells able to counteract the stress toward cell survival. PMID:27990148

  5. 5-AIQ inhibits H{sub 2}O{sub 2}-induced apoptosis through reactive oxygen species scavenging and Akt/GSK-3β signaling pathway in H9c2 cardiomyocytes

    SciTech Connect

    Park, Eun-Seok; Kang, Jun Chul; Kang, Do-Hyun; Jang, Yong Chang; Yi, Kyu Yang; Chung, Hun-Jong; Park, Jong Seok; Kim, Bokyung; Feng, Zhong-Ping; Shin, Hwa-Sup

    2013-04-01

    Poly(adenosine 5′-diphosphate ribose) polymerase (PARP) is a nuclear enzyme activated by DNA strand breaks and plays an important role in the tissue injury associated with ischemia and reperfusion. The aim of the present study was to investigate the protective effect of 5-aminoisoquinolinone (5-AIQ), a PARP inhibitor, against oxidative stress-induced apoptosis in H9c2 cardiomyocytes. 5-AIQ pretreatment significantly protected against H{sub 2}O{sub 2}-induced cell death, as determined by the XTT assay, cell counting, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, and Western blot analysis of apoptosis-related proteins such as caspase-3, Bax, and Bcl-2. Upregulation of antioxidant enzymes such as manganese superoxide dismutase and catalase accompanied the protective effect of 5-AIQ on H{sub 2}O{sub 2}-induced cell death. Our data also showed that 5-AIQ pretreatment protected H9c2 cells from H{sub 2}O{sub 2}-induced apoptosis by triggering activation of Akt and glycogen synthase kinase-3β (GSK-3β), and that the protective effect of 5-AIQ was diminished by the PI3K inhibitor LY294002 at a concentration that effectively abolished 5-AIQ-induced Akt and GSK-3β activation. In addition, inhibiting the Akt/GSK-3β pathway by LY294002 significantly attenuated the 5-AIQ-mediated decrease in cleaved caspase-3 and Bax activation and H9c2 cell apoptosis induction. Taken together, these results demonstrate that 5-AIQ prevents H{sub 2}O{sub 2}-induced apoptosis in H9c2 cells by reducing intracellular reactive oxygen species production, regulating apoptosis-related proteins, and activating the Akt/GSK-3β pathway. - Highlights: ► 5-AIQ, a PARP inhibitor, decreased H{sub 2}O{sub 2}-induced H9c2 cell death and apoptosis. ► 5-AIQ upregulated antioxidant Mn-SOD and catalase, while decreasing ROS production. ► 5-AIQ decreased H{sub 2}O{sub 2}-induced increase in cleaved caspase-3 and Bax and decrease in Bcl2. ► 5-AIQ activated Akt and GSK-3

  6. Reactive oxygen scavenging activity of matured whiskey and its active polyphenols.

    PubMed

    Koga, K; Taguchi, A; Koshimizu, S; Suwa, Y; Yamada, Y; Shirasaka, N; Yoshizumi, H

    2007-04-01

    The quality of whiskey is known to improve remarkably by its storage over many years. This process is commonly termed "maturing." In this process, polyphenols derived from lignin and tannin of the barrel have an important role in not only forming the matured flavor and taste but also contributing to the advance of clustering ethanol and water in whiskey. It is also likely that polyphenols generally possess reactive oxygen (RO) scavenging activity. The present study evaluated the RO scavenging activity (free-radical scavenging activity, H(2)O(2) reduction activity under peroxidase coculture, and H(2)O(2)scavenging activity) of 24 single malt whiskeys with a maturation age of 10 to 30 y produced in Japanese, Scotch (Islay), or Scotch (Speyside and Highland) regions. Single malt whiskey not only showed RO scavenging activity but there was also a positive correlation between this activity and the maturation age of whiskey exceeding the difference resulting from the manufacturing region. A nonvolatile fraction derived from the barrel was responsible for RO scavenging activity. In particular, the contents of ellagic and gallic acids and lyoniresinol, the main polyphenolic compounds in whiskey, increased with maturation age. For the free-radical scavenging activity per molecule, each compound was 1.68 to 3.14 times that of trolox (a water-soluble vitamin E). The activities of ellagic acid, gallic acid, and lyoniresinol in the whiskey (Yamazaki 18) were equivalent to that of 80.3, 31.2, and 11.1 ppm trolox, respectively. Accordingly, the total activity of these 3 compounds accounted for about 20% of the activity of the whiskey (630.7 ppm trolox).

  7. Key role in ecosystem functioning of scavengers reliant on a single common species

    NASA Astrophysics Data System (ADS)

    Inger, Richard; Per, Esra; Cox, Daniel T. C.; Gaston, Kevin J.

    2016-07-01

    The importance of species richness in maintaining ecosystem function in the field remains unclear. Recent studies however have suggested that in some systems functionality is maintained by a few abundant species. Here we determine this relationship by quantifying the species responsible for a key ecosystem role, carcass removal by scavengers. We find that, unlike those within largely unaltered environments, the scavenger community within our highly altered system is dominated by a single species, the Carrion crow, despite the presence of a number of other scavenging species. Furthermore, we find no relationship between abundance of crows and carcass removal. However, the overall activity of crows predicts carcass biomass removal rate in an asymptotic manner, suggesting that a relatively low level of abundance and scavenging activity is required to maintain this component of ecosystem function.

  8. Key role in ecosystem functioning of scavengers reliant on a single common species

    PubMed Central

    Inger, Richard; Per, Esra; Cox, Daniel T.C.; Gaston, Kevin J.

    2016-01-01

    The importance of species richness in maintaining ecosystem function in the field remains unclear. Recent studies however have suggested that in some systems functionality is maintained by a few abundant species. Here we determine this relationship by quantifying the species responsible for a key ecosystem role, carcass removal by scavengers. We find that, unlike those within largely unaltered environments, the scavenger community within our highly altered system is dominated by a single species, the Carrion crow, despite the presence of a number of other scavenging species. Furthermore, we find no relationship between abundance of crows and carcass removal. However, the overall activity of crows predicts carcass biomass removal rate in an asymptotic manner, suggesting that a relatively low level of abundance and scavenging activity is required to maintain this component of ecosystem function. PMID:27404915

  9. Scavenging of photogenerated oxidative species by antimuscarinic drugs: atropine and derivatives.

    PubMed

    Criado, Susana; Guardianelli, Carina; Tuninetti, Jimena; Molina, Patricia; García, Norman A

    2002-01-01

    The quenching ability of photogenerated oxidative species by some antimuscarinic drugs generically named atropines (e.g. atropine [I] eucatropine [II], homatropine [III] and scopolamine [IV]) have been investigated employing stationary photolysis, polarographic detection of dissolved oxygen, stationary and time-resolved fluorescence spectroscopy, and laser flash photolysis. Using Rose Bengal as a dye sensitiser for singlet molecular oxygen, O(2)((1)Delta(g)), generation, compounds I-IV behave as moderate chemical plus physical quenchers of the oxidative species. Correlation between kinetic and electrochemical data indicates that the process is possibly driven by a charge-transfer interaction. The situation is somewhat more complicated employing the natural pigment riboflavin (Rf) as a sensitiser. Compounds I and II complex Rf ground state, diminishing the quenching ability towards singlet and triplet excited state of the pigment. On the other hand, compounds III and IV effectively quench Rf excited states, protecting the pigment against photodegradation. Under anaerobic conditions, semireduced Rf (Rf(.-)) is formed through quenching of excited triplet Rf. Nevertheless, although Rf(.-) is a well-known generator of the reactive species superoxide radical anion by reductive quenching in the presence of oxygen, the process of O(2)((1)Delta(g)) production prevails over superoxide radical generation, due to the relatively low rate constants for the quenching of triplet Rf by the atropines (in the order of 10(7) M(-1)s(-1) for compounds III and IV) in comparison to the rate constant for the quenching by ground state oxygen, approximately two orders of magnitude higher, yielding O(2)((1)Delta(g)). Compound I is the most promising O(2)((1)Delta(g)) physical scavenger, provided that it exhibits the higher value for the overall quenching rate constant and only 11% of the quenching process leads to its own chemical damage.

  10. S-allylcysteine scavenges singlet oxygen and hypochlorous acid and protects LLC-PK(1) cells of potassium dichromate-induced toxicity.

    PubMed

    Medina-Campos, Omar Noel; Barrera, Diana; Segoviano-Murillo, Sabina; Rocha, Diana; Maldonado, Perla D; Mendoza-Patiño, Nicandro; Pedraza-Chaverri, José

    2007-10-01

    It has been found that S-allylcysteine (SAC), a garlic-derived compound, has in vivo and in vitro antioxidant properties. In addition, it is known that SAC is able to scavenge different reactive oxygen or nitrogen species including superoxide anion (O(2)(-)), hydrogen peroxide (H(2)O(2)), hydroxyl radical (OH()), and peroxynitrite anion (ONOO(-)) although the IC(5O) values for each reactive species has not been calculated and the potential ability of SAC to scavenge singlet oxygen ((1)O(2)) and hypochlorous acid (HOCl) has not been explored. The purposes of this work was (a) to explore the potential ability of SAC to scavenge (1)O(2) and HOCl, (b) to further characterize the O(2)(-), H(2)O(2), OH(), and ONOO(-) scavenging ability of SAC by measuring the IC(50) values using in vitro assays, and (c) to explore the potential ability of SAC to ameliorate the potassium dichromate (K(2)Cr(2)O(7))-induced cytotoxicity in LLC-PK1 cells in which oxidative stress is involved. The scavenging activity was compared against the following reference compounds: N-acetylcysteine for O(2)(-), sodium pyruvate for H(2)O(2), dimethylthiourea for OH(), lipoic acid and glutathione for (1)O(2), lipoic acid for HOCl, and penicillamine for ONOO(-). It was found that SAC was able to scavenge concentration-dependently all the species assayed with the following IC(5O) (mean+/-SEM, mM): O(2)(-) (14.49+/-1.67), H(2)O(2) (68+/-1.92), OH() (0.68+/-0.06), (1)O(2) (1.93+/-0.27), HOCl (2.86+/-0.15), and ONOO(-) (0.80+/-0.05). When the ability of SAC to scavenge these species was compared to those of the reference compounds it was found that the efficacy of SAC (a) to scavenge O(2)(-), H(2)O(2), OH(), and ONOO(-) was lower, (b) to scavenge HOCl was similar, and (c) to scavenge (1)O(2) was higher. In addition, it was found that SAC was able to prevent K(2)Cr(2)O(7)-induced toxicity in LLC-PK1 cells in culture. It was showed for the first time that SAC is able to scavenge (1)O(2) and HOCl and to

  11. Overexpression of CaAPX Induces Orchestrated Reactive Oxygen Scavenging and Enhances Cold and Heat Tolerances in Tobacco

    PubMed Central

    Wang, Jiangying; Wu, Bin; Fan, Zhengqi; Li, Xinlei; Ni, Sui

    2017-01-01

    Ascorbate peroxidase (APX) acts indispensably in synthesizing L-ascorbate (AsA) which is pivotal to plant stress tolerance by detoxifying reactive oxygen species (ROS). Enhanced activity of APX has been shown to be a key step for genetic engineering of improving plant tolerance. However it needs a deeper understanding on the maintenance of cellular ROS homeostasis in response to stress. In this study, we identified and characterized an APX (CaAPX) gene from Camellia azalea. Quantitative real-time PCR (qRT-PCR) analysis showed that CaAPX was expressed in all tissues and peaked in immature green fruits; the expression levels were significantly upregulated upon cold and hot stresses. Transgenic plants displayed marked enhancements of tolerance under both cold and heat treatments, and plant growth was correlated with CaAPX expression levels. Furthermore, we monitored the activities of several ROS-scavenging enzymes including Cu/Zn-SOD, CAT, DHAR, and MDHAR, and we showed that stress tolerance was synchronized with elevated activities of ROS-scavenging. Moreover, gene expression analysis of ROS-scavenging enzymes revealed a role of CaAPX to orchestrate ROS signaling in response to temperature stresses. Overall, this study presents a comprehensive characterization of cellular response related to CaAPX expression and provides insights to breed crops with high temperature tolerances. PMID:28386551

  12. Carbocysteine lysine salt monohydrate (SCMC-LYS) is a selective scavenger of reactive oxygen intermediates (ROIs).

    PubMed

    Brandolini, Laura; Allegretti, Marcello; Berdini, Valerio; Cervellera, Maria Neve; Mascagni, Patrizia; Rinaldi, Matteo; Melillo, Gabriella; Ghezzi, Pietro; Mengozzi, Manuela; Bertini, Riccardo

    2003-01-01

    Carbocysteine lysine salt monohydrate (SCMC-Lys) is a well-known mucoactive drug whose therapeutic efficacy is commonly related to the ability of SCMC-Lys to replace fucomucins by sialomucins. The aim of this study was to determine if SCMC-Lys could exert an anti-oxidant action by scavenging reactive oxygen intermediates (ROIs). Our results show that SCMC-Lys proved effective as a selective scavenger of hypochlorous acid (HOCl) and hydroxyl radical (OH.), this effect being related to the reactivity of the SCMC tioether group. The scavenger activity of SCMC-Lys was observed in free cellular system as well as in activated human polymorphonuclear neutrophils (PMNs). SCMC-Lys scavenger activity on HOCl was paralleled by a powerful protection from HOCl-mediated inactivation of alpha1-antitripsin (alpha1-AT) inhibitor, the main serum protease inhibitor. Production of interleukin-(IL-)8, a major mediator of PMN recruitment in inflammatory diseases, is known to be mediated by intracellular OH. SCMC-Lys significantly reduced IL-8 production on stimulated human peripheral blood mononuclear cells (PBMCs) in the same range of concentrations affecting OH. activity. It is concluded that SCMC-Lys could exert, in addition to its mucoactive capacity, an anti-oxidant action, thus contributing to the therapeutic efficacy of SCMC-Lys.

  13. A Different Pattern of Production and Scavenging of Reactive Oxygen Species in Halophytic Eutrema salsugineum (Thellungiella salsuginea) Plants in Comparison to Arabidopsis thaliana and Its Relation to Salt Stress Signaling

    PubMed Central

    Pilarska, Maria; Wiciarz, Monika; Jajić, Ivan; Kozieradzka-Kiszkurno, Małgorzata; Dobrev, Petre; Vanková, Radomíra; Niewiadomska, Ewa

    2016-01-01

    Isolated thylakoids from halophytic Eutrema salsugineum (Thellungiella salsuginea) produces more H2O2 in comparison to glycophytic Arabidopsis thaliana. The first objective of this study was to verify whether this feature is relevant also to the intact chloroplasts and leaves. Enhanced H2O2 levels in chloroplasts and leaves of E. salsugineum were positively verified with several methods (electron microscopy, staining with Amplex Red and with diaminobenzidine). This effect was associated with a decreased ratio of O2•–/H2O2 in E. salsugineum in comparison to A. thaliana as detected by electron paramagnetic resonance method. As a next step, we tested how this specific ROS signature of halophytic species affects the antioxidant status and down-stream components of ROS signaling. Comparison of enzymatic antioxidants revealed a decreased activity of ascorbate peroxidase (APX), enhanced activity of glutathione peroxidase, and the presence of thylakoid-bound forms of iron superoxide dismutase (FeSOD) and APX in E. salsugineum. These cues were, however, independent from application of salt stress. The typical H2O2-dependent cellular responses, namely the levels of glucosinolates and stress-related hormones were determined. The total glucosinolate content in E. salsugineum water-treated leaves was higher than in A. thaliana and increased after salinity treatment. Treatment with salinity up-regulated all of tested stress hormones, their precursors and catabolites [abscisic acid (ABA), dihydrophaseic acid, phaseic acid, 1-aminocyclopropane-1-carboxylic acid, salicylic acid, jasmonic acid, cis-(+)-12-oxo-phytodienoic acid and jasmonoyl-L-isoleucine] in A. thaliana, whereas in E. salsugineum only a stimulation in ethylene synthesis and ABA catabolism was noted. Obtained results suggest that constitutively enhanced H2O2 generation in chloroplasts of E. salsugineum might be a crucial component of stress-prepardeness of this halophytic species. It shapes a very efficient

  14. Reactive oxygen species in periodontitis

    PubMed Central

    Dahiya, Parveen; Kamal, Reet; Gupta, Rajan; Bhardwaj, Rohit; Chaudhary, Karun; Kaur, Simerpreet

    2013-01-01

    Recent epidemiological studies reveal that more than two-third of the world's population suffers from one of the chronic forms of periodontal disease. The primary etiological agent of this inflammatory disease is a polymicrobial complex, predominantly Gram negative anaerobic or facultative bacteria within the sub-gingival biofilm. These bacterial species initiate the production of various cytokines such as interleukin-8 and TNF-α, further causing an increase in number and activity of polymorphonucleocytes (PMN) along with these cytokines, PMNs also produce reactive oxygen species (ROS) superoxide via the respiratory burst mechanism as the part of the defence response to infection. ROS just like the interleukins have deleterious effects on tissue cells when produced in excess. To counter the harmful effects of ROS, human body has its own defence mechanisms to eliminate them as soon as they are formed. The aim of this review is to focus on the role of different free radicals, ROS, and antioxidants in the pathophysiology of periodontal tissue destruction. PMID:24174716

  15. Effect of Remote Oxygen Scavenging on Electrical Properties of Ge-Based Metal-Oxide-Semiconductor Capacitors

    NASA Astrophysics Data System (ADS)

    Fadida, Sivan; Nyns, Laura; Van Elshocht, Sven; Eizenberg, Moshe

    2017-01-01

    Remote oxygen scavenging has been studied in a metal/high- k dielectric/GeO2/Ge stack, where a thin Ti layer inserted into the metal/high- k dielectric interface serves as the scavenger. First, we established that remote oxygen scavenging indeed occurs specifically in the studied HfO2/Al2O3/GeO2/Ge stack. It was also established that the source for oxygen is decomposition of the GeO2 layer. Then, the effect of remote oxygen scavenging of the GeO2 layer on the electrical characteristics of the metal/oxide/Ge capacitors was investigated. The electrical properties were studied in comparison with identical gate stacks with a Pt electrode, before and after annealing. Although a decrease in effective oxide thickness was demonstrated as a result of this process, clear degradation of the interface electrical quality was observed after scavenging. Initiation of the scavenging process was witnessed upon deposition of Ti at room temperature, emphasizing that this process could not be controlled.

  16. Improved survival using oxygen free radical scavengers in the presence of ischemic bowel anastomosis.

    PubMed

    Bergren, C T; Bodzin, J H; Cortez, J A

    1988-06-01

    A rat model was developed to determine the efficacy of oxygen free radical scavenger compounds in improving small bowel anastomotic healing in ischemia. 50 Sprague-Dawley rats underwent laparotomy and were divided into groups: I. sham operation; II. ischemia produced by ligation of mesenteric vessels along 3-5 cm of bowel; III. bowel transection and anastomosis; IV. ligation of vessels with bowel transection and anastomosis; V. ligation of vessels, bowel transection and IV administration of superoxide dismutase (SOD) (5000 U/kg) prior to anastomosis. All surviving animals were sacrificed after 2 weeks. Anastomotic tensile strength and histology were evaluated. Percent survival and the average length of survival for all groups is seen in the table below. (table: see text) A significant decrease in survival was present with the anastomotic group and the ischemic anastomotic group when compared with controls. An improved survival similar to ischemia alone was present in SOD group. No significant difference was noted between SOD and control groups. The results of this study indicate an improved survival rate and length of survival similar to controls in animals undergoing ischemic and penetrating injury to the bowel with the use of oxygen free radical scavenger compounds prior to anastomosis.

  17. REACTIVE OXYGEN SPECIES IN PULMONARY VASCULAR REMODELING

    PubMed Central

    Aggarwal, Saurabh; Gross, Christine M.; Sharma, Shruti; Fineman, Jeffrey R.; Black, Stephen M.

    2014-01-01

    The pathogenesis of pulmonary hypertension is a complex multifactorial process that involves the remodeling of pulmonary arteries. This remodeling process encompasses concentric medial thickening of small arterioles, neomuscularization of previously nonmuscular capillary-like vessels, and structural wall changes in larger pulmonary arteries. The pulmonary arterial muscularization is characterized by vascular smooth muscle cell (SMC) hyperplasia and hypertrophy. In addition, in uncontrolled pulmonary hypertension, the clonal expansion of apoptosis-resistant endothelial cells leads to the formation of plexiform lesions. Based upon a large number of studies in animal models, the three major stimuli that drive the vascular remodeling process are inflammation, shear stress and hypoxia. Although, the precise mechanisms by which these stimuli impair pulmonary vascular function and structure are unknown, reactive oxygen species (ROS)-mediated oxidative damage appears to play an important role. ROS are highly reactive due to their unpaired valence shell electron. Oxidative damage occurs when the production of ROS exceeds the quenching capacity of the anti-oxidant mechanisms of the cell. ROS can be produced from complexes in the cell membrane (nicotinamide adenine dinucleotide phosphate-oxidase), cellular organelles (peroxisomes and mitochondria), and in the cytoplasm (xanthine oxidase). Furthermore, low levels of tetrahydrobiopterin (BH4) and L-arginine the rate limiting co-factor and substrate for endothelial nitric oxide synthase (eNOS), can cause the uncoupling of eNOS, resulting in decreased NO production and increased ROS production. This review will focus on the ROS generation systems, scavenger antioxidants, and oxidative stress associated alterations in vascular remodeling in pulmonary hypertension. PMID:23897679

  18. Seroepidemiologic Survey of Potential Pathogens in Obligate and Facultative Scavenging Avian Species in California.

    PubMed

    Straub, Mary H; Kelly, Terra R; Rideout, Bruce A; Eng, Curtis; Wynne, Janna; Braun, Josephine; Johnson, Christine K

    2015-01-01

    Throughout the world, populations of scavenger birds are declining rapidly with some populations already on the brink of extinction. Much of the current research into the factors contributing to these declines has focused on exposure to drug residues, lead, and other toxins. Despite increased monitoring of these declining populations, little is known about infectious diseases affecting scavenger bird species. To assess potential infectious disease risks to both obligate and facultative scavenger bird species, we performed a serosurvey for eleven potential pathogens in three species of scavenging birds in California: the California condor (Gymnogyps californianus), turkey vulture (Cathartes aura) and golden eagle (Aquila chrysaetos). California condors were seropositive for avian adenovirus, infectious bronchitis virus, Mycoplasma gallisepticum, avian paramyxovirus-2, West Nile virus (WNV) and Toxoplasma gondii. Golden eagles were seropositive for avian adenovirus, Chlamydophila psittaci and Toxoplasma gondii, and turkey vultures were seropositive for avian adenovirus, Chlamydophila psittaci, avian paramyxovirus-1, Toxoplasma gondii and WNV. Risk factor analyses indicated that rearing site and original release location were significantly associated with a positive serologic titer to WNV among free-flying condors. This study provides preliminary baseline data on infectious disease exposure in these populations for aiding in early disease detection and provides potentially critical information for conservation of the endangered California condor as it continues to expand its range and encounter new infectious disease threats.

  19. Seroepidemiologic Survey of Potential Pathogens in Obligate and Facultative Scavenging Avian Species in California

    PubMed Central

    Straub, Mary H.; Kelly, Terra R.; Rideout, Bruce A.; Eng, Curtis; Wynne, Janna; Braun, Josephine; Johnson, Christine K.

    2015-01-01

    Throughout the world, populations of scavenger birds are declining rapidly with some populations already on the brink of extinction. Much of the current research into the factors contributing to these declines has focused on exposure to drug residues, lead, and other toxins. Despite increased monitoring of these declining populations, little is known about infectious diseases affecting scavenger bird species. To assess potential infectious disease risks to both obligate and facultative scavenger bird species, we performed a serosurvey for eleven potential pathogens in three species of scavenging birds in California: the California condor (Gymnogyps californianus), turkey vulture (Cathartes aura) and golden eagle (Aquila chrysaetos). California condors were seropositive for avian adenovirus, infectious bronchitis virus, Mycoplasma gallisepticum, avian paramyxovirus-2, West Nile virus (WNV) and Toxoplasma gondii. Golden eagles were seropositive for avian adenovirus, Chlamydophila psittaci and Toxoplasma gondii, and turkey vultures were seropositive for avian adenovirus, Chlamydophila psittaci, avian paramyxovirus-1, Toxoplasma gondii and WNV. Risk factor analyses indicated that rearing site and original release location were significantly associated with a positive serologic titer to WNV among free-flying condors. This study provides preliminary baseline data on infectious disease exposure in these populations for aiding in early disease detection and provides potentially critical information for conservation of the endangered California condor as it continues to expand its range and encounter new infectious disease threats. PMID:26606755

  20. Comparison of lignin derivatives as substrates for laccase-catalyzed scavenging of oxygen in coatings and films

    PubMed Central

    2014-01-01

    Background Lignin derivatives are phenylpropanoid biopolymers derived from pulping and biorefinery processes. The possibility to utilize lignin derivatives from different types of processes in advanced enzyme-catalyzed oxygen-scavenging systems intended for active packaging was explored. Laccase-catalyzed oxidation of alkali lignin (LA), hydrolytic lignin (LH), organosolv lignin (LO), and lignosulfonates (LS) was compared using oxygen-scavenging coatings and films in liquid and gas phase systems. Results When coatings containing lignin derivatives and laccase were immersed in a buffered aqueous solution, the oxygen-scavenging capability increased in the order LO < LH < LA < LS. Experiments with coatings containing laccase and LO, LH or LA incubated in oxygen-containing gas in air-tight chambers and at a relative humidity (RH) of 100% showed that paperboard coated with LO and laccase reduced the oxygen content from 1.0% to 0.4% during a four-day period, which was far better than the results obtained with LA or LH. LO-containing coatings incubated at 92% RH also displayed activity, with a decrease in oxygen from 1.0% to 0.7% during a four-day period. The oxygen scavenging was not related to the content of free phenolic hydroxyl groups, which increased in the order LO < LS < LH < LA. LO and LS were selected for further studies and films containing starch, clay, glycerol, laccase and LO or LS were characterized using gel permeation chromatograpy, dynamic mechanical analysis, and wet stability. Conclusions The investigation shows that different lignin derivatives exhibit widely different properties as a part of active coatings and films. Results indicate that LS and LO were most suitable for the application studied and differences between them were attributed to a higher degree of laccase-catalyzed cross-linking of LS than of LO. Inclusion in active-packaging systems offers a new way to utilize some types of lignin derivatives from biorefining

  1. Phytate, reactive oxygen species and colorectal cancer.

    PubMed

    Owen, R W; Spiegelhalder, B; Bartsch, H

    1998-05-01

    Reproducible high-performance liquid chromatography methods have been developed and validated which allow an accurate quantification of phytic acid in faeces and food and reactive oxygen species in an in vitro model system and in faecal specimens. When applied to the evaluation of reactive oxygen species generation by faeces, this method has shown that 1:100 dilutions of matrix obtained from stool samples of adenoma patients are capable of generating significant quantities of reactive oxygen species as evinced by the production of diphenols from salicylic acid. Moreover, it has been shown that the major product of HO. attack on salicylic acid is 2,5-dihydroxy benzoic acid and not 2, 3-dihydroxy benzoic acid as previously reported. In the presence of the antioxidant ascorbic acid the inhibitory capacity of phytic acid on the generation of reactive oxygen species is completely subverted. Therefore, the kinetics of reactive oxygen species production by faeces is currently under further investigation by high-performance liquid chromatography and chemiluminescence in various patient groups and may give an insight into the role of reactive oxygen species in the aetiology of colorectal cancer.

  2. Reactive oxygen species mediate lethality induced by far-UV in Escherichia coli cells.

    PubMed

    Gomes, A A; Silva-Júnior, A C T; Oliveira, E B; Asad, L M B O; Reis, N C S C; Felzenszwalb, I; Kovary, K; Asad, N R

    2005-01-01

    The involvement of reactive oxygen species (ROS) in the induction of DNA damage to Escherichia coli cells caused by UVC (254 nm) irradiation was studied. We verified the expression of the soxS gene induced by UVC (254 nm) and its inhibition by sodium azide, a singlet oxygen (1O2) scavenger. Additional results showed that a water-soluble carotenoid (norbixin) protects against the lethal effects of UVC. These results suggest that UVC radiation can also cause ROS-mediated lethality.

  3. Understanding and Controlling Cu-Catalyzed Graphene Nucleation: The Role of Impurities, Roughness, and Oxygen Scavenging

    PubMed Central

    2016-01-01

    The mechanism by which Cu catalyst pretreatments control graphene nucleation density in scalable chemical vapor deposition (CVD) is systematically explored. The intrinsic and extrinsic carbon contamination in the Cu foil is identified by time-of-flight secondary ion mass spectrometry as a major factor influencing graphene nucleation and growth. By selectively oxidizing the backside of the Cu foil prior to graphene growth, a drastic reduction of the graphene nucleation density by 6 orders of magnitude can be obtained. This approach decouples surface roughness effects and at the same time allows us to trace the scavenging effect of oxygen on deleterious carbon impurities as it permeates through the Cu bulk. Parallels to well-known processes in Cu metallurgy are discussed. We also put into context the relative effectiveness and underlying mechanisms of the most widely used Cu pretreatments, including wet etching and electropolishing, allowing a rationalization of current literature and determination of the relevant parameter space for graphene growth. Taking into account the wider CVD growth parameter space, guidelines are discussed for high-throughput manufacturing of “electronic-quality” monolayer graphene films with domain size exceeding 1 mm, suitable for emerging industrial applications, such as electronics and photonics. PMID:28133416

  4. Enhanced single-particle brightness and photostability of semiconductor polymer dots by enzymatic oxygen scavenging system

    NASA Astrophysics Data System (ADS)

    Liu, Zhihe; Yang, Yingkun; Sun, Zezhou; Wu, Changfeng

    2016-12-01

    Semiconductor polymer dots (Pdots) are emerging as an excellent fluorescent probe in biology and medicine. However, the photostability of Pdots can't meet the requirements of long term single-particle imaging and tracking applications. Here we describe the enhanced single-particle brightness and photostability of Pdots by using an efficient enzymatic oxygen scavenging system (OSS). Pdots with particle diameters of 21 nm and 43 nm (PFBT21 and PFBT43) were prepared by a nanoprecipitation method. Single-particle imaging and photobleaching were performed to investigate the effect of OSS on the per-particle brightness and photostability of Pdots. Our results indicate that the single-particle brightness of the PFBT21 Pdots in OSS was enhanced nearly two times as compare to the PFBT21 Pdots in water. The photobleaching percentages of PFBT21 and PFBT43 in OSS were determined to be 29% and 33%, respectively. These values are decreased by 2-3 times as compared to those of the same Pdots in water, indicating the significantly improved photostability of Pdots by OSS. This study provides a promising approach for enhancing photostability of Pdots in long term single-particle tracking.

  5. Rosacea, Reactive Oxygen Species, and Azelaic Acid

    PubMed Central

    2009-01-01

    Rosacea is a common skin condition thought to be primarily an inflammatory disorder. Neutrophils, in particular, have been implicated in the inflammation associated with rosacea and mediate many of their effects through the release of reactive oxygen species. Recently, the role of reactive oxygen species in the pathophysiology of rosacea has been recognized. Many effective agents for rosacea, including topical azelaic acid and topical metronidazole, have anti-inflammatory properties. in-vitro models have demonstrated the potent antioxidant effects of azelaic acid, providing a potential mechanistic explanation for its efficacy in the treatment of rosacea. PMID:20967185

  6. Indomethacin inactivates gastric peroxidase to induce reactive-oxygen-mediated gastric mucosal injury and curcumin protects it by preventing peroxidase inactivation and scavenging reactive oxygen.

    PubMed

    Chattopadhyay, Ishita; Bandyopadhyay, Uday; Biswas, Kaushik; Maity, Pallab; Banerjee, Ranajit K

    2006-04-15

    We have investigated the mechanism of indomethacin-induced gastric ulcer caused by reactive oxygen species (ROS) and the gastroprotective effect of curcumin thereon. Curcumin dose-dependently blocks indomethacin-induced gastric lesions, showing 82% protection at 25 mg/kg. Indomethacin-induced oxidative damage by ROS as shown by increased lipid peroxidation and thiol depletion is almost completely blocked by curcumin. Indomethacin causes nearly fivefold increase in hydroxyl radical (()OH) and significant inactivation of gastric mucosal peroxidase to elevate endogenous H(2)O(2) and H(2)O(2)-derived ()OH, which is prevented by curcumin. In vitro studies indicate that indomethacin inactivates peroxidase irreversibly only in presence of H(2)O(2) by acting as a suicidal substrate. 5,5-Dimethyl-pyrroline-N-oxide (DMPO) protects the peroxidase, indicating involvement of indomethacin radical in the inactivation. Indomethacin radical was also detected in the peroxidase-indomethacin-H(2)O(2) system as DMPO adduct (a(N) = 15 G, a(beta)(H) = 16 G) by electron spin resonance spectroscopy. Curcumin protects the peroxidase in a concentration-dependent manner and consumes H(2)O(2) for its oxidation as a suitable substrate of the peroxidase, thereby blocking indomethacin oxidation. Curcumin can also scavenge ()OH in vitro. We suggest that curcumin protects gastric damage by efficient removal of H(2)O(2) and H(2)O(2) -derived ()OH by preventing peroxidase inactivation by indomethacin.

  7. Superoxide Dismutases and Reactive Oxygen Species

    SciTech Connect

    Cabelli, D.E.

    2011-01-01

    The 'free radical theory' of aging was introduced over a half-century ago. In this theory, much of the deleterious effects of aging were attributed to the cumulative buildup of damage from reactive oxygen species. When discussing reactive oxygen species (ROS) in aerobic systems, both superoxide radicals (O{sub 2}{sup -}) and superoxide dismutases (SODs) are considered to play prominent roles. O{sub 2}{sup -} is formed by attachment of the electron to oxygen (O{sub 2}) that is present in tens to hundreds of micromolar concentration in vivo. SODs are enzymes that serve to eliminate O{sub 2}{sup -} by rapidly converting it to O{sub 2} and hydrogen peroxide (H{sub 2}O{sub 2}). Both the radical and the enzyme will be discussed with the focus on the systems that are present in humans.

  8. Mitochondrial formation of reactive oxygen species

    PubMed Central

    Turrens, Julio F

    2003-01-01

    The reduction of oxygen to water proceeds via one electron at a time. In the mitochondrial respiratory chain, Complex IV (cytochrome oxidase) retains all partially reduced intermediates until full reduction is achieved. Other redox centres in the electron transport chain, however, may leak electrons to oxygen, partially reducing this molecule to superoxide anion (O2−•). Even though O2−• is not a strong oxidant, it is a precursor of most other reactive oxygen species, and it also becomes involved in the propagation of oxidative chain reactions. Despite the presence of various antioxidant defences, the mitochondrion appears to be the main intracellular source of these oxidants. This review describes the main mitochondrial sources of reactive species and the antioxidant defences that evolved to prevent oxidative damage in all the mitochondrial compartments. We also discuss various physiological and pathological scenarios resulting from an increased steady state concentration of mitochondrial oxidants. PMID:14561818

  9. Changes in oxygen consumption induced by t-butyl hydroperoxide in perfused rat liver. Effect of free-radical scavengers.

    PubMed Central

    Videla, L A; Villena, M I; Donoso, G; Giulivi, C; Boveris, A

    1984-01-01

    The addition of t-butyl hydroperoxide to perfused rat liver elicited a biphasic effect on hepatic respiration. A rapid fall in liver oxygen consumption was initially observed, followed by a recovery phase leading to respiratory rates higher than the initial steady-state values of oxygen uptake. This overshoot in hepatic oxygen uptake was abolished by free-radical scavengers such as (+)-cyanidanol-3 or butylated hydroxyanisole at concentrations that did not alter mitochondrial respiration. (+)-Cyanidanol-3 was also able to facilitate the recovery of respiration, the diminution in the calculated rate of hydroperoxide utilization and the decrease in liver GSH content produced by two consecutive pulses of t-butyl hydroperoxide. It is suggested that the t-butyl hydroperoxide-induced overshoot in liver respiration is related to increased utilization of oxygen for lipid peroxidation as a consequence of free radicals produced in the scission of the hydroperoxide by cellular haemoproteins. PMID:6508746

  10. Formation and Detoxification of Reactive Oxygen Species

    ERIC Educational Resources Information Center

    Kuciel, Radoslawa; Mazurkiewicz, Aleksandra

    2004-01-01

    A model of reactive oxygen species metabolism is proposed as a laboratory exercise for students. The superoxide ion in this model is generated during the reaction of oxidation of xanthine, catalyzed by xanthine oxidase. The effect of catalase, superoxide dismutase, and allopurinol on superoxide ion generation and removal in this system is also…

  11. Shark cartilage-containing preparation: protection against reactive oxygen species.

    PubMed

    Felzenszwalb, I; Pelielo de Mattos, J C; Bernardo-Filho, M; Caldeira-de-Araújo, A

    1998-12-01

    There is overwhelming evidence to indicate that free radicals cause oxidative damage to lipids, proteins and nucleic acids and are involved in the pathogenesis of several degenerative diseases. Therefore, antioxidants, which can neutralize free radicals, may be of central importance in the prevention of these disease states. The protection that fruits and vegetables provide against disease has been attributed to the various antioxidants contained in them. Recently, an anti-inflammatory and analgesic activity of a water-soluble fraction from shark cartilage has been described. Using electrophoretical assays, bacteria survival and transformation and the Salmonella/mammalian-microsome assay, we investigated the putative role of shark cartilage-containing preparation in protecting cells against reactive oxygen species induced DNA damage and mutagenesis. If antimutagens are to have any impact on human disease, it is essential that they are specifically directed against the most common mutagens in daily life. Our data suggest that shark cartilage-containing preparation can play a scavenger role for reactive oxygen species and protects cells against inactivation and mutagenesis.

  12. Endophytic Bacterium-Triggered Reactive Oxygen Species Directly Increase Oxygenous Sesquiterpenoid Content and Diversity in Atractylodes lancea

    PubMed Central

    Zhou, Jia-Yu; Yuan, Jie; Li, Xia; Ning, Yi-Fan

    2015-01-01

    Oxygenous terpenoids are active components of many medicinal plants. However, current studies that have focused on enzymatic oxidation reactions cannot comprehensively clarify the mechanisms of oxygenous terpenoid synthesis and diversity. This study shows that an endophytic bacterium can trigger the generation of reactive oxygen species (ROS) that directly increase oxygenous sesquiterpenoid content and diversity in Atractylodes lancea. A. lancea is a famous but endangered Chinese medicinal plant that contains abundant oxygenous sesquiterpenoids. Geo-authentic A. lancea produces a wider range and a greater abundance of oxygenous sesquiterpenoids than the cultivated herb. Our previous studies have shown the mechanisms behind endophytic promotion of the production of sesquiterpenoid hydrocarbon scaffolds; however, how endophytes promote the formation of oxygenous sesquiterpenoids and their diversity is unclear. After colonization by Pseudomonas fluorescens ALEB7B, oxidative burst and oxygenous sesquiterpenoid accumulation in A. lancea occur synchronously. Treatment with exogenous hydrogen peroxide (H2O2) or singlet oxygen induces oxidative burst and promotes oxygenous sesquiterpenoid accumulation in planta. Conversely, pretreatment of plantlets with the ROS scavenger ascorbic acid significantly inhibits the oxidative burst and oxygenous sesquiterpenoid accumulation induced by P. fluorescens ALEB7B. Further in vitro oxidation experiments show that several oxygenous sesquiterpenoids can be obtained from direct oxidation caused by H2O2 or singlet oxygen. In summary, this study demonstrates that endophytic bacterium-triggered ROS can directly oxidize oxygen-free sesquiterpenoids and increase the oxygenous sesquiterpenoid content and diversity in A. lancea, providing a novel explanation of the mechanisms of oxygenous terpenoid synthesis in planta and an essential complementarity to enzymatic oxidation reactions. PMID:26712554

  13. Reactive oxygen species in phagocytic leukocytes

    PubMed Central

    2008-01-01

    Phagocytic leukocytes consume oxygen and generate reactive oxygen species in response to appropriate stimuli. The phagocyte NADPH oxidase, a multiprotein complex, existing in the dissociated state in resting cells becomes assembled into the functional oxidase complex upon stimulation and then generates superoxide anions. Biochemical aspects of the NADPH oxidase are briefly discussed in this review; however, the major focus relates to the contributions of various modes of microscopy to our understanding of the NADPH oxidase and the cell biology of phagocytic leukocytes. PMID:18597105

  14. Mitochondrial Reactive Oxygen Species at the Heart of the Matter: New Therapeutic Approaches for Cardiovascular Diseases

    PubMed Central

    Kornfeld, Opher S.; Hwang, Sunhee; Disatnik, Marie-Hélène; Chen, Che-Hong; Qvit, Nir; Mochly-Rosen, Daria

    2015-01-01

    Reactive oxygen species (ROS) have been implicated in a variety of age-related diseases including multiple cardiovascular disorders. However, translation of ROS scavengers (anti-oxidants) into the clinic has not been successful. These anti-oxidants grossly reduce total levels of cellular ROS including ROS that participate in physiological signaling. In this review, we challenge the traditional anti-oxidant therapeutic approach that targets ROS directly with novel approaches that improve mitochondrial functions to more effectively treat cardiovascular diseases. PMID:25999419

  15. Antimicrobial Actions of Reactive Oxygen Species

    PubMed Central

    Fang, Ferric C.

    2011-01-01

    ABSTRACT Everything should be as simple as it can be, but not simpler.—Attributed to Albert Einstein (1) Reactive oxygen species (ROS) are produced by host phagocytes and exert antimicrobial actions against a broad range of pathogens. The observable antimicrobial actions of ROS are highly dependent on experimental conditions. This perspective reviews recent controversies regarding ROS in Salmonella-phagocyte interactions and attempts to reconcile conflicting observations from different laboratories. PMID:21896680

  16. REACTIVE OXYGEN SPECIES: IMPACT ON SKELETAL MUSCLE

    PubMed Central

    Powers, Scott K.; Ji, Li Li; Kavazis, Andreas N.; Jackson, Malcolm J.

    2014-01-01

    It is well established that contracting muscles produce both reactive oxygen and nitrogen species. Although the sources of oxidant production during exercise continue to be debated, growing evidence suggests that mitochondria are not the dominant source. Regardless of the sources of oxidants in contracting muscles, intense and prolonged exercise can result in oxidative damage to both proteins and lipids in the contracting myocytes. Further, oxidants regulate numerous cell signaling pathways and modulate the expression of many genes. This oxidant-mediated change in gene expression involves changes at transcriptional, mRNA stability, and signal transduction levels. Furthermore, numerous products associated with oxidant-modulated genes have been identified and include antioxidant enzymes, stress proteins, and mitochondrial electron transport proteins. Interestingly, low and physiological levels of reactive oxygen species are required for normal force production in skeletal muscle, but high levels of reactive oxygen species result in contractile dysfunction and fatigue. Ongoing research continues to explore the redox-sensitive targets in muscle that are responsible for both redox-regulation of muscle adaptation and oxidant-mediated muscle fatigue. PMID:23737208

  17. Reactive oxygen species in the immune system.

    PubMed

    Yang, Yuhui; Bazhin, Alexandr V; Werner, Jens; Karakhanova, Svetlana

    2013-06-01

    Reactive oxygen species (ROS) are a group of highly reactive chemicals containing oxygen produced either exogenously or endogenously. ROS are related to a wide variety of human disorders, such as chronic inflammation, age-related diseases and cancers. Besides, ROS are also essential for various biological functions, including cell survival, cell growth, proliferation and differentiation, and immune response. At present there are a number of excellent publications including some reviews about functions of these molecules either in normal cell biology or in pathophysiology. In this work, we reviewed available information and recent advances about ROS in the main immune cell types and gave summary about functions of these highly reactive molecules both in innate immunity as conservative defense mechanisms and in essential immune cells involved in adaptive immunity, and particularly in immune suppression.

  18. Effects of exogenous β-carotene, a chemical scavenger of singlet oxygen, on the millisecond rise of chlorophyll a fluorescence of cyanobacterium Synechococcus sp. PCC 7942.

    PubMed

    Stamatakis, Kostas; Papageorgiou, George C; Govindjee

    2016-12-01

    Singlet-excited oxygen ((1)O 2(*) ) has been recognized as the most destructive member of the reactive oxygen species (ROS) which are formed during oxygenic photosynthesis by plants, algae, and cyanobacteria. ROS and (1)O 2(*) are known to damage protein and phospholipid structures and to impair photosynthetic electron transport and de novo protein synthesis. Partial protection is afforded to photosynthetic organism by the β-carotene (β-Car) molecules which accompany chlorophyll (Chl) a in the pigment-protein complexes of Photosystem II (PS II). In this paper, we studied the effects of exogenously added β-Car on the initial kinetic rise of Chl a fluorescence (10-1000 μs, the OJ segment) from the unicellular cyanobacterium Synechococcus sp. PCC7942. We show that the added β-Car enhances Chl a fluorescence when it is excited at an intensity of 3000 μmol photons m(-2) s(-1) but not when excited at 1000 μmol photons m(-2) s(-1). Since β-Car is an efficient scavenger of (1)O 2(*) , as well as a quencher of (3)Chl a (*) (precursor of (1)O 2(*) ), both of which are more abundant at higher excitations, we assume that the higher Chl a fluorescence in its presence signifies a protective effect against photo-oxidative damages of Chl proteins. The protective effect of added β-Car is not observed in O2-depleted cell suspensions. Lastly, in contrast to β-Car, a water-insoluble molecule, a water-soluble scavenger of (1)O 2(*) , histidine, provides no protection to Chl proteins during the same time period (10-1000 μs).

  19. Antioxidant and free radical scavenging activity of flavonol glycosides from different Aconitum species.

    PubMed

    Braca, Alessandra; Fico, Gelsomina; Morelli, Ivano; De Simone, Francesco; Tomè, Franca; De Tommasi, Nunziatina

    2003-05-01

    Bioassay-guided fractionation by 1,1-diphenyl-2-dipicrylhydrazyl (DPPH) radical scavenging test of polar extracts of some Italian Aconitum species (A. napellus subsp. tauricum, A. napellus subsp. neomontanum, A. paniculatum, A. vulparia) led to the isolation of 13 flavonol glycosides: quercetin 3-O-(6-trans-caffeoyl)-beta-glucopyranosyl-(1-->2)-beta-glucopyranoside-7-O-alpha-rhamnopyranoside (1), kaempferol 3-O-(6-trans-caffeoyl)-beta-glucopyranosyl-(1-->2)-beta-glucopyranoside-7-O-alpha-rhamnopyranoside (2), quercetin 3-O-(6-trans-p-coumaroyl)-beta-glucopyranosyl-(1-->2)-beta-glucopyranoside-7-O-alpha-rhamnopyranoside (3), kaempferol 3-O-(6-trans-p-coumaroyl)-beta-glucopyranosyl-(1-->2)-beta-glucopyranoside-7-O-alpha-rhamnopyranoside (4), quercetin 7-O-(6-trans-caffeoyl)-beta-glucopyranosyl-(1-->3)-alpha-rhamnopyranoside-3-O-beta-glucopyranoside (5), kaempferol 7-O-(6-trans-caffeoyl)-beta-glucopyranosyl-(1-->3)-alpha-rhamnopyranoside-3-O-beta-glucopyranoside (6), kaempferol 7-O-(6-trans-p-coumaroyl)-beta-glucopyranosyl-(1-->3)-alpha-rhamnopyranoside-3-O-beta-glucopyranoside (7), kaempferol 3-O-beta-(2"-acetyl)galactopyranoside (8), kaempferol 3-O-beta-(2"-acetyl)galactopyranoside-7-O-alpha-arabinopyranoside (9), quercetin 3-O-beta-(2"-acetyl)galactopyranoside-7-O-alpha-arabinopyranoside (10), quercetin 3,7-di-O-alpha-rhamnopyranoside (11), kaempferol 3,7-di-O-alpha-rhamnopyranoside (12) and quercetin 3-O-beta-glucopyranoside-7-O-alpha-rhamnopyranoside (13). Their antioxidant activity (AA) was determined by measuring free radical scavenging activity by DPPH test and the coupled oxidation of beta-carotene and linoleic acid assay. The results showed that 5 is the most active compound in the DPPH free-radical scavenging test (IC(50) 1.9 microM) while in the coupled oxidation of beta-carotene and linoleic acid assay compound 1 has the highest inhibitory ratio after 1h (58.9%). Some structure-activity relationships on the AA were obtained.

  20. Mutagenicity of arsenic in mammalian cells: role of reactive oxygen species

    NASA Technical Reports Server (NTRS)

    Hei, T. K.; Liu, S. X.; Waldren, C.

    1998-01-01

    Arsenite, the trivalent form of arsenic present in the environment, is a known human carcinogen that lacked mutagenic activity in bacterial and standard mammalian cell mutation assays. We show herein that when evaluated in an assay (AL cell assay), in which both intragenic and multilocus mutations are detectable, that arsenite is in fact a strong dose-dependent mutagen and that it induces mostly large deletion mutations. Cotreatment of cells with the oxygen radical scavenger dimethyl sulfoxide significantly reduces the mutagenicity of arsenite. Thus, the carcinogenicity of arsenite can be explained at least in part by it being a mutagen that depends on reactive oxygen species for its activity.

  1. Some dinophycean red tide plankton species generate a superoxide scavenging substance.

    PubMed

    Sato, Emiko; Niwano, Yoshimi; Matsuyama, Yukihiko; Kim, Daekyung; Nakashima, Takuji; Oda, Tatsuya; Kohno, Masahiro

    2007-03-01

    Recent studies indicate that some raphidophycean red tide flagellates produce substances able to scavenge superoxide, whereas there have been no reports on superoxide scavenger production by dinophycean red tide flagellates. In this study, we examined the superoxide-scavenging activity of aqueous extracts from dinophycean red tide flagellates, Gymnodinium spp., Scrippsiella trochoidea, and Karenia sp., by a luminol analog L-012-dependent chemiluminescence (CL) method and an electron spin resonance (ESR)-spin trapping method, and compared the activity to that of raphidophycean red tide flagellates, Chattonella spp., Heterosigma akashiwo, and Fibrocapsa japonica. In the experiment applying the L-012-dependent CL method, only the aqueous extracts from raphidophycean red tide flagellates showed superoxide-scavenging activity. On the other hand, applying the ESR-spin trapping method, we found that the aqueous extracts from dinophycean red tide flagellates also showed superoxide-scavenging activity. This is the first report on the production of a superoxide-scavenger by dinophycean red tide flagellates.

  2. Yields of single-strand breaks in double-stranded calf thymus DNA irradiated in aqueous solution in the presence of oxygen and scavengers

    SciTech Connect

    Udovicic, Lj.; Mark, F.; Bothe, E.

    1994-11-01

    Yields of radiation-induced single-strand breaks in double-stranded calf thymus DNA have been measured as a function of OH scavenger concentration in N{sub 2}O/O{sub 2}-saturated aqueous solution. The experimental data are well represented by a theoretical model based on non-homogeneous reaction kinetics, without the need to adjust any parameter. The good agreement between experimental and theoretical data is taken as evidence that, in the presence of oxygen, the main effect of added scavengers with respect to the formation of single-strand breaks in double-stranded DNA is OH radical scavenging. 30 refs., 3 figs., 1 tab.

  3. Adaptations for scavenging by three diverse bathyla species, Eptatretus stouti, Neptunea amianta and Orchomene obtusus

    NASA Astrophysics Data System (ADS)

    Tamburri, Mario N.; Barry, James P.

    1999-12-01

    Many deep-sea animals derive part of their nutrition from rare and unpredictable food falls. However, traits that allow organisms inhabiting the sea floor to exploit carrion are poorly understood. We found in laboratory experiments that hagfish ( Eptatretus stouti), gastropods ( Neptunea amianta) and amphipods ( Orchomene obtusus) survived extended periods of starvation, in some cases for more than a year. When exposed to odors emitted from carrion, most individuals of E. stouti and O. obtusus began searching for food within seconds, whereas none responded to the scent of the live prey. In contrast, the slow crawling N. amianta readily consumed carrion but showed no apparent response to any odor solutions tested. Because more motile animals exhibited lower thresholds for response to signal molecules, sensitivity to chemical cues appears related to species mobility. Hagfish were also found to defend carrion from some competitors by releasing slime when feeding. Though varying dramatically in size, morphology, locomotive ability, and phylogeny, these three species all possess traits well suited for a scavenging lifestyle.

  4. The effect of a Ta oxygen scavenger layer on HfO2-based resistive switching behavior: thermodynamic stability, electronic structure, and low-bias transport.

    PubMed

    Zhong, Xiaoliang; Rungger, Ivan; Zapol, Peter; Nakamura, Hisao; Asai, Yoshihiro; Heinonen, Olle

    2016-03-14

    Reversible resistive switching between high-resistance and low-resistance states in metal-oxide-metal heterostructures makes them very interesting for applications in random access memories. While recent experimental work has shown that inserting a metallic "oxygen scavenger layer" between the positive electrode and oxide improves device performance, the fundamental understanding of how the scavenger layer modifies the heterostructure properties is lacking. We use density functional theory to calculate thermodynamic properties and conductance of TiN/HfO2/TiN heterostructures with and without a Ta scavenger layer. First, we show that Ta insertion lowers the formation energy of low-resistance states. Second, while the Ta scavenger layer reduces the Schottky barrier height in the high-resistance state by modifying the interface charge at the oxide-electrode interface, the heterostructure maintains a high resistance ratio between high- and low-resistance states. Finally, we show that the low-bias conductance of device on-states becomes much less sensitive to the spatial distribution of oxygen removed from the HfO2 in the presence of the Ta layer. By providing a fundamental understanding of the observed improvements with scavenger layers, we open a path to engineer interfaces with oxygen scavenger layers to control and enhance device performance. In turn, this may enable the realization of a non-volatile low-power memory technology with concomitant reduction in energy consumption by consumer electronics and offering significant benefits to society.

  5. Study of oxygen scavenging PET-based films activated by water

    NASA Astrophysics Data System (ADS)

    Rossi, Gabriella; Scarfato, Paola; Incarnato, Loredana

    2016-05-01

    In this work an active barrier system consisting of a thin and transparent film based on polyethylene terephthalate (PET) was studied. Dynamic oxygen absorption measurements were performed at different values of relative humidity and temperature, pointing out that humidity is a key factor in activating the oxidation of the polymer sample. Moreover, the thermal and optical properties of the films were investigated and a good correlation was found between the crystallinity increase and the consequent transparency reduction occurring after the oxygen absorption.

  6. Signaling by reactive oxygen and nitrogen species in skin diseases.

    PubMed

    Afanas'ev, Igor B

    2010-06-01

    For many years the formation of reactive oxygen and nitrogen species (ROS) and (RNS) in living organisms has been considered to be dangerous phenomenon due to their damaging action on biomolecules. However, present studies demonstrated another important activity of ROS and RNS: their signaling functions in physiological and pathological processes. In this work we discuss the new data concerning a role of ROS and RNS in many enzymatic/gene cascades causing damaging changes during the development of skin diseases and pathological disorders (skin cancer, the toxic effects of irradiation on the skin, and skin wounding). It has been suggested that the enhancement of ROS formation in tumor cells through the inactivation of mitochondrial MnSOD or the activation of NADPH oxidase leads to apoptosis and might be applied for developing a new cancer therapy. On the other hand ROS overproduction might stimulate malignant transformation of melanoma. Role of ROS signaling is also considered in the damaging action of UVA, UVB, and IRA irradiation on the skin and the processes of wound healing. In the last part of review the possibility of the right choice of antioxidants and free radical scavengers for the treatment of skin disease is discussed.

  7. Ethanol stimulates epithelial sodium channels by elevating reactive oxygen species.

    PubMed

    Bao, Hui-Fang; Song, John Z; Duke, Billie J; Ma, He-Ping; Denson, Donald D; Eaton, Douglas C

    2012-12-01

    Alcohol affects total body sodium balance, but the molecular mechanism of its effect remains unclear. We used single-channel methods to examine how ethanol affects epithelial sodium channels (ENaC) in A6 distal nephron cells. The data showed that ethanol significantly increased both ENaC open probability (P(o)) and the number of active ENaC in patches (N). 1-Propanol and 1-butanol also increased ENaC activity, but iso-alcohols did not. The effects of ethanol were mimicked by acetaldehyde, the first metabolic product of ethanol, but not by acetone, the metabolic product of 2-propanol. Besides increasing open probability and apparent density of active channels, confocal microscopy and surface biotinylation showed that ethanol significantly increased α-ENaC protein in the apical membrane. The effects of ethanol on ENaC P(o) and N were abolished by a superoxide scavenger, 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy (TEMPOL) and blocked by the phosphatidylinositol 3-kinase inhibitor LY294002. Consistent with an effect of ethanol-induced reactive oxygen species (ROS) on ENaC, primary alcohols and acetaldehyde elevated intracellular ROS, but secondary alcohols did not. Taken together with our previous finding that ROS stimulate ENaC, the current results suggest that ethanol stimulates ENaC by elevating intracellular ROS probably via its metabolic product acetaldehyde.

  8. Formation of protein S-nitrosylation by reactive oxygen species.

    PubMed

    Hlaing, K Htet; Clément, M-V

    2014-09-01

    In the present study, the formation of whole cellular S-nitrosylated proteins (protein-SNOs) by the reactive oxygen species (ROS), hydrogen peroxide (H2O2), and superoxide (O2(•-)) is demonstrated. A spectrum of protein cysteine oxidative modifications was detected upon incubation of serum-starved mouse embryonic fibroblasts with increasing concentrations of exogenous H2O2, ranging from exclusive protein-SNOs at low concentrations to a mixture of protein-SNOs and other protein oxidation at higher concentrations to exclusively non-SNO protein oxidation at the highest concentrations of the oxidant used. Furthermore, formation of protein-SNOs was also detected upon inhibition of the antioxidant protein Cu/Zn superoxide dismutase that results in an increase in intracellular concentration of O2(•-). These results were further validated using the phosphatase and tensin homologue, PTEN, as a model of a protein sensitive to oxidative modifications. The formation of protein-SNOs by H2O2 and O2(•-) was prevented by the NO scavenger, c-PTIO, as well as the peroxinitrite decomposition catalyst, FETPPS, and correlated with the production or the consumption of nitric oxide (NO), respectively. These data suggest that the formation of protein-SNOs by H2O2 or O2(•-) requires the presence or the production of NO and involves the formation of the nitrosylating intermediate, peroxinitrite.

  9. Reactive oxygen species and the cardiovascular system.

    PubMed

    Taverne, Yannick J H J; Bogers, Ad J J C; Duncker, Dirk J; Merkus, Daphne

    2013-01-01

    Ever since the discovery of free radicals, many hypotheses on the deleterious actions of reactive oxygen species (ROS) have been proposed. However, increasing evidence advocates the necessity of ROS for cellular homeostasis. ROS are generated as inherent by-products of aerobic metabolism and are tightly controlled by antioxidants. Conversely, when produced in excess or when antioxidants are depleted, ROS can inflict damage to lipids, proteins, and DNA. Such a state of oxidative stress is associated with many pathological conditions and closely correlated to oxygen consumption. Although the deleterious effects of ROS can potentially be reduced by restoring the imbalance between production and clearance of ROS through administration of antioxidants (AOs), the dosage and type of AOs should be tailored to the location and nature of oxidative stress. This paper describes several pathways of ROS signaling in cellular homeostasis. Further, we review the function of ROS in cardiovascular pathology and the effects of AOs on cardiovascular outcomes with emphasis on the so-called oxidative paradox.

  10. Complex cellular responses to reactive oxygen species.

    PubMed

    Temple, Mark D; Perrone, Gabriel G; Dawes, Ian W

    2005-06-01

    Genome-wide analyses of yeast provide insight into cellular responses to reactive oxygen species (ROS). Many deletion mutants are sensitive to at least one ROS, but no one oxidant is representative of 'oxidative stress' despite the widespread use of a single compound such as H(2)O(2). This has major implications for studies of pathological situations. Cells have a range of mechanisms for maintaining resistance that involves either induction or repression of many genes and extensive remodeling of the transcriptome. Cells have constitutive defense systems that are largely unique to each oxidant, but overlapping, inducible repair systems. The pattern of the transcriptional response to a particular ROS depends on its concentration, and 'classical' antioxidant systems that are induced by high concentrations of ROS can be repressed when cells adapt to low concentrations of ROS.

  11. Physiological roles of mitochondrial reactive oxygen species.

    PubMed

    Sena, Laura A; Chandel, Navdeep S

    2012-10-26

    Historically, mitochondrial reactive oxygen species (mROS) were thought to exclusively cause cellular damage and lack a physiological function. Accumulation of ROS and oxidative damage have been linked to multiple pathologies, including neurodegenerative diseases, diabetes, cancer, and premature aging. Thus, mROS were originally envisioned as a necessary evil of oxidative metabolism, a product of an imperfect system. Yet few biological systems possess such flagrant imperfections, thanks to the persistent optimization of evolution, and it appears that oxidative metabolism is no different. More and more evidence suggests that mROS are critical for healthy cell function. In this Review, we discuss this evidence following some background on the generation and regulation of mROS.

  12. Vertical Transport Processes for Inert and Scavenged Species: TRACE-A Measurements

    NASA Technical Reports Server (NTRS)

    Chatfield, Robert B.; Chan, K. Roland (Technical Monitor)

    1997-01-01

    upper troposphere. We expect to be able to attribute this to either parameterization reasons (inadequacy of this parameterization at the large 100km scale) or other reasons. Nevertheless, the qualitative nature of deep transport by clouds shows up well in the simulations. As for scavengable species, the simulations predict tens of micrograms per standard cubic meter of smoke aerosol in the boundary layer. In a straightforward illustration of our simple bulk-mass scavenging parameterization, to one or two micrograms per standard cubic meter of smoke aerosol in the free troposphere just above the source regions: very high concentrations for the free troposphere. We expect to report on comparisons of these predictions to a variety of observations.

  13. Role of activated oxygen species on the mutagenicity of benzo[a]pyrene.

    PubMed

    Wei, C E; Allen, K; Misra, H P

    1989-06-01

    Different scavengers of active oxygen species (superoxide dismutase, catalase, mannitol and dimethylfuran) were tested in the Ames Salmonella assay to determine the role of the reactive oxygen species in the benzo[a]pyrene (B[a]P) mutagenesis process. Exogenously added superoxide dismutase or catalase at 10-100 micrograms ml-1 top agar, or 3-12 mM mannitol showed no effect on B[a]P mutagenicity in the presence of S9 mix. However, dimethylfuran (DMF), a singlet oxygen scavenger, inhibited in a dose-related manner the mutagenic response of B[a]P in the presence of the microsomal fraction. DMF at 3 and 6 mM inhibited the number of revertants by 69 and 93% for strain TA 100, and 76 and 78% for TA98, respectively. DMF at these levels was neither toxic nor mutagenic to the bacteria. The result indicates that singlet oxygen may play an important role in promoting B[a]P mutagenicity.

  14. Influence of reactive oxygen species on the sterilization of microbes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The influence of reactive oxygen species on living cells, including various microbes, is discussed. A sterilization experiment with bacterial endospores reveals that an argoneoxygen plasma jet very effectively kills endospores of Bacillus atrophaeus (ATCC 9372), thereby indicating that oxygen radic...

  15. Production and Consumption of Reactive Oxygen Species by Fullerenes

    EPA Science Inventory

    Reactive oxygen species (ROS) are one of the most important intermediates in chemical, photochemical, and biological processes. To understand the environmental exposure and toxicity of fullerenes better, the production and consumption of ROS (singlet oxygen, superoxide, hydrogen ...

  16. Pharmacology of Free Radicals and the Impact of Reactive Oxygen Species on the Testis

    PubMed Central

    Aprioku, Jonah Sydney

    2013-01-01

    The role of free radicals in normal cellular functions and different pathological conditions has been a focus of pharmacological studies in the recent past. Reactive oxygen species (ROS) and free radicals in general are essential for cell signaling and other vital physiological functions; however, excessive amounts can cause alteration in cellular reduction-oxidation (redox) balance, and disrupt normal biological functions. When there is an imbalance between activities of ROS and antioxidant/scavenging defense systems, oxidative stress (OS) occurs. A good number of studies have shown OS is involved in the development of several disease conditions, including male infertility. In the present article, generation of free radicals and their effects, as well as the mechanisms of antioxidant/scavenging defense systems are discussed, with particular focus on the testis. The review also discusses the contribution of OS on testicular dysfunction and briefly focuses on some OS-induced conditions that will alter testicular function. PMID:24551570

  17. Identification of the Active Species in Photochemical Hole Scavenging Reactions of Methanol on TiO2

    SciTech Connect

    Shen, Mingmin; Henderson, Michael A.

    2011-11-03

    Molecular and dissociative methanol adsorption species were prepared on rutile TiO2(110) surfaces to study photocatalytic oxidation of methanol in ultrahigh vacuum (UHV) using temperature-programmed desorption (TPD). Adsorbed methoxy groups (CH3O-) were found to be the photoactive form of adsorbed methanol converted to adsorbed formaldehyde and a surface OH group by hole-mediated C-H bond cleavage. These results suggest that adsorbed methoxy is the effective hole scavenger in photochemical reactions involving methanol.

  18. Reactive oxygen species and redox compartmentalization.

    PubMed

    Kaludercic, Nina; Deshwal, Soni; Di Lisa, Fabio

    2014-01-01

    Reactive oxygen species (ROS) formation and signaling are of major importance and regulate a number of processes in physiological conditions. A disruption in redox status regulation, however, has been associated with numerous pathological conditions. In recent years it has become increasingly clear that oxidative and reductive modifications are confined in a spatio-temporal manner. This makes ROS signaling similar to that of Ca(2+) or other second messengers. Some subcellular compartments are more oxidizing (such as lysosomes or peroxisomes) whereas others are more reducing (mitochondria, nuclei). Moreover, although more reducing, mitochondria are especially susceptible to oxidation, most likely due to the high number of exposed thiols present in that compartment. Recent advances in the development of redox probes allow specific measurement of defined ROS in different cellular compartments in intact living cells or organisms. The availability of these tools now allows simultaneous spatio-temporal measurements and correlation between ROS generation and organelle and/or cellular function. The study of ROS compartmentalization and microdomains will help elucidate their role in physiology and disease. Here we will examine redox probes currently available and how ROS generation may vary between subcellular compartments. Furthermore, we will discuss ROS compartmentalization in physiological and pathological conditions focusing our attention on mitochondria, since their vulnerability to oxidative stress is likely at the basis of several diseases.

  19. Fluoranthene fumigation and exogenous scavenging of reactive oxygen intermediates (ROI) in evergreen Japanese red pine seedlings (Pinus densiflora Sieb. et. Zucc.).

    PubMed

    Oguntimehin, Ilemobayo; Sakugawa, Hiroshi

    2008-06-01

    Generation of reactive oxygen intermediates (ROI) such as O(2)(-), H(2)O(2), and *OH is known to be a major mechanism of damage in biological systems. This study investigated and compared effectiveness of scavenging ROI generated in fluoranthene (FLU) pre-fumigated Japanese red pine seedlings. Three kinds of eco-physiological assessments were used to express the impact of the different fumigants used inside the green house. Gas exchange measurements showed negative changes induced by 10 microM FLU on Japanese pine seedlings during a 10 d exposure period whilst no negative change was found during a 5 d exposure period. Moreover, during a 14 d FLU exposure incorporating ROI scavengers, results revealed that chlorophyll fluorescence, needle chemical contents and needle dry mass per unit area of the seedlings were affected. The negative effects of FLU on the conifer were dependent on both the dose and period of FLU fumigation. Peroxidase (PERO), superoxide dismutase (SOD) and mannitol (MANN) were all effective scavengers of ROI. MANN scavenged *OH, the most lethal of the ROI. For practicable use, MANN is more economical, and may be the best ROI scavenger among the three considered. It can be concluded that efficient scavenging of ROI in biological systems is important to mitigate the negative effects of FLU on Japanese red pine trees.

  20. The effect of a Ta oxygen scavenger layer on HfO2-based resistive switching behavior: Thermodynamic stability, electronic structure, and low-bias transport

    DOE PAGES

    Zhong, Xiaoliang; Rungger, Ivan; Zapol, Peter; ...

    2016-02-15

    Reversible resistive switching between high-resistance and low-resistance states in metal-oxide-metal heterostructures makes them very interesting for applications in random access memories. While recent experimental work has shown that inserting a metallic "oxygen scavenger layer'' between the positive electrode and oxide improves device performance, the fundamental understanding of how the scavenger layer modifies the heterostructure properties is lacking. We use density functional theory to calculate thermodynamic properties and conductance of TiN/HfO2/TiN heterostructures with and without a Ta scavenger layer. First, we show that Ta insertion lowers the formation energy of low-resistance states. Second, while the Ta scavenger layer reduces the Schottkymore » barrier height in the high-resistance state by modifying the interface charge at the oxide-electrode interface, the heterostructure maintains a high resistance ratio between high-and low-resistance states. Lastly, we show that the low-bias conductance of device on-states becomes much less sensitive to the spatial distribution of oxygen removed from the HfO2 in the presence of the Ta layer. By providing a fundamental understanding of the observed improvements with scavenger layers, we open a path to engineer interfaces with oxygen scavenger layers to control and enhance device performance. In turn, this may enable the realization of a non-volatile low-power memory technology with concomitant reduction in energy consumption by consumer electronics and offering significant benefits to society.« less

  1. Skin, Reactive Oxygen Species, and Circadian Clocks

    PubMed Central

    Ndiaye, Mary A.; Nihal, Minakshi; Wood, Gary S.

    2014-01-01

    Abstract Significance: Skin, a complex organ and the body's first line of defense against environmental insults, plays a critical role in maintaining homeostasis in an organism. This balance is maintained through a complex network of cellular machinery and signaling events, including those regulating oxidative stress and circadian rhythms. These regulatory mechanisms have developed integral systems to protect skin cells and to signal to the rest of the body in the event of internal and environmental stresses. Recent Advances: Interestingly, several signaling pathways and many bioactive molecules have been found to be involved and even important in the regulation of oxidative stress and circadian rhythms, especially in the skin. It is becoming increasingly evident that these two regulatory systems may, in fact, be interconnected in the regulation of homeostasis. Important examples of molecules that connect the two systems include serotonin, melatonin, vitamin D, and vitamin A. Critical Issues: Excessive reactive oxygen species and/or dysregulation of antioxidant system and circadian rhythms can cause critical errors in maintaining proper barrier function and skin health, as well as overall homeostasis. Unfortunately, the modern lifestyle seems to contribute to increasing alterations in redox balance and circadian rhythms, thereby posing a critical problem for normal functioning of the living system. Future Directions: Since the oxidative stress and circadian rhythm systems seem to have areas of overlap, future research needs to be focused on defining the interactions between these two important systems. This may be especially important in the skin where both systems play critical roles in protecting the whole body. Antioxid. Redox Signal. 20, 2982–2996. PMID:24111846

  2. Reactive Oxygen Species in Combustion Aerosols

    NASA Astrophysics Data System (ADS)

    Balasubramanian, R.; See, S.

    2007-12-01

    Research on airborne particulate matter (PM) has received increased concern in recent years after it was identified as a major component of the air pollution mix that is strongly associated with premature mortality and morbidity. Particular attention has been paid to understanding the potential health impacts of fine particles (PM2.5), which primarily originate from combustion sources. One group of particulate-bound chemical components of health concern is reactive oxygen species (ROS), which include molecules such as hydrogen peroxide (H2O2), ions such as hypochlorite ion (OCl-), free radicals such as hydroxyl radical (·OH) and superoxide anion (·O2-) which is both an ion and a radical. However, the formation of ROS in PM is not clearly understood yet. Furthermore, the concentration of ROS in combustion particles of different origin has not been quantified. The primary objective of this work is to study the effect of transition metals on the production of ROS in PM2.5 by determining the concentrations of ROS and metals. Both soluble and total metals were measured to evaluate their respective associations with ROS. PM2.5 samples were collected from several outdoor and indoor combustion sources, including those emitted from on-road vehicles, food cooking, incense sticks, and cigarette smoke. PM2.5 samples were also collected from the background air in both the ambient outdoor and indoor environments to assess the levels of particulate-bound transition metals and ROS with no combustion activities in the vicinity of sampling locations. Results obtained from this comprehensive study on particulate-bound ROS will be presented and discussed.

  3. ROI-scavenging enzyme activities as toxicity biomarkers in three species of marine microalgae exposed to model contaminants (copper, Irgarol and atrazine).

    PubMed

    Lozano, Pablo; Trombini, Chiara; Crespo, Elena; Blasco, Julián; Moreno-Garrido, Ignacio

    2014-06-01

    There is a need to develop efficient tools to prevent damage to marine ecosystems due to pollution. Since microalgae play a key role in marine ecosystems, they are considered potentially useful for quick and sensitive toxicity bioassays. In this study an integrative analysis has been carried out of the anti-oxidant enzyme activities of marine microalgae species. Three marine microalgae species (Cylindrotheca closterium, a benthic diatom; Phaeodactylum tricornutum, a diatom which has been used as model organism in toxicity bioassays; and Rhodomonas salina, a cryptophyceae which is considered to present a certain level of heterotrophy) were exposed to selected concentrations of three model pollutants: copper (5 and 10µg L(-1)), atrazine (25 and 50µg L(-1)) and Irgarol (0.5 and 1.0µg L(-1)). These pollutant concentrations are environmentally relevant for coastal ecosystems, and have been selected for checking the efficiency of the reactive oxygen intermediate (ROI) scavenging enzyme system of these organisms. Superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APx) and glutathione peroxidase (GPx) activities were measured at the end of 24h exposure. The integrated biomarker response (IBR) index - in our case for oxidative stress - has been employed to evaluate the ROI-scavenging enzyme system for each species and each treatment. In general, the SOD and CAT enzyme activities measured were higher in exposed populations than in controls, whereas APx and GPx activities showed the opposite trend. These microalgae showed significant responses of oxidative stress biomarkers at environmentally relevant concentrations for the assayed pollutants and short exposure periods, conditions that most other model organisms cannot match. Therefore microalgae present clear advantages over other species for their prospective employment in an "early warning system".

  4. Clade age and diversification rate variation explain disparity in species richness among water scavenger beetle (Hydrophilidae) lineages.

    PubMed

    Bloom, Devin D; Fikáček, Martin; Short, Andrew E Z

    2014-01-01

    Explaining the disparity of species richness across the tree of life is one of the great challenges in evolutionary biology. Some lineages are exceptionally species rich, while others are relatively species poor. One explanation for heterogeneity among clade richness is that older clades are more species rich because they have had more time to accrue diversity than younger clades. Alternatively, disparity in species richness may be due to among-lineage diversification rate variation. Here we investigate diversification in water scavenger beetles (Hydrophilidae), which vary in species richness among major lineages by as much as 20 fold. Using a time-calibrated phylogeny and comparative methods, we test for a relationship between clade age and species richness and for shifts in diversification rate in hydrophilids. We detected a single diversification rate increase in Megasternini, a relatively young and species rich clade whose diversity might be explained by the stunning diversity of ecological niches occupied by this clade. We find that Amphiopini, an old clade, is significantly more species poor than expected, possibly due to its restricted geographic range. The remaining lineages show a correlation between species richness and clade age, suggesting that both clade age and variation in diversification rates explain the disparity in species richness in hydrophilids. We find little evidence that transitions between aquatic, semiaquatic, and terrestrial habitats are linked to shifts in diversification rates.

  5. Clade Age and Diversification Rate Variation Explain Disparity in Species Richness among Water Scavenger Beetle (Hydrophilidae) Lineages

    PubMed Central

    Bloom, Devin D.; Fikáček, Martin; Short, Andrew E. Z.

    2014-01-01

    Explaining the disparity of species richness across the tree of life is one of the great challenges in evolutionary biology. Some lineages are exceptionally species rich, while others are relatively species poor. One explanation for heterogeneity among clade richness is that older clades are more species rich because they have had more time to accrue diversity than younger clades. Alternatively, disparity in species richness may be due to among-lineage diversification rate variation. Here we investigate diversification in water scavenger beetles (Hydrophilidae), which vary in species richness among major lineages by as much as 20 fold. Using a time-calibrated phylogeny and comparative methods, we test for a relationship between clade age and species richness and for shifts in diversification rate in hydrophilids. We detected a single diversification rate increase in Megasternini, a relatively young and species rich clade whose diversity might be explained by the stunning diversity of ecological niches occupied by this clade. We find that Amphiopini, an old clade, is significantly more species poor than expected, possibly due to its restricted geographic range. The remaining lineages show a correlation between species richness and clade age, suggesting that both clade age and variation in diversification rates explain the disparity in species richness in hydrophilids. We find little evidence that transitions between aquatic, semiaquatic, and terrestrial habitats are linked to shifts in diversification rates. PMID:24887453

  6. Phytochemical constituents and in vitro radical scavenging activity of different Aloe species.

    PubMed

    Lucini, Luigi; Pellizzoni, Marco; Pellegrino, Roberto; Molinari, Gian Pietro; Colla, Giuseppe

    2015-03-01

    The phytochemical profile of Aloe barbadensis Mill. and Aloe arborescens Mill. was investigated using colorimetric assays, triple quadrupole and time-of-flight mass spectrometry, focusing on phenolic secondary metabolites in the different leaf portions. Hydroxycinnamic acids, several characteristic anthrones and chromones, the phenolic dimer feralolide and flavonoids such as flavones and isoflavones were identified. The stable radical DPPH test and the ORAC assay were then used to determine the in vitro radical scavenging. The outer green rind was the most active, while the inner parenchyma was much less effective. The 5-methylchromones aloesin, aloeresin A and aloesone were the most active among the pure secondary metabolites tested. The results suggest that several compounds are likely to contribute to the overall radical scavenging activity, and indicate that leaf portion must be taken into account when the plant is used for its antioxidant properties.

  7. Inhibitory activities of soluble and bound millet seed phenolics on free radicals and reactive oxygen species.

    PubMed

    Chandrasekara, Anoma; Shahidi, Fereidoon

    2011-01-12

    Oxidative stress, caused by reactive oxygen species (ROS), is responsible for modulating several pathological conditions and aging. Soluble and bound phenolic extracts of commonly consumed millets, namely, kodo, finger (Ravi), finger (local), foxtail, proso, little, and pearl, were investigated for their phenolic content and inhibition of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and ROS, namely, hydroxyl radical, peroxyl radical, hydrogen peroxide (H(2)O(2)), hypochlorous acid (HOCl), and singlet oxygen ((1)O(2)). Inhibition of DPPH and hydroxyl radicals was detrmined using electron paramagnetic resonance (EPR) spectroscopy. The peroxyl radical inhibitory activity was measured using the oxygen radical absorbance capacity (ORAC) assay. The scavenging of H(2)O(2), HOCl, and (1)O(2) was evaluated using colorimetric methods. The results were expressed as micromoles of ferulic acid equivalents (FAE) per gram of grain on a dry weight basis. In addition, major hydroxycinnamic acids were identified and quantified using high-performance liquid chromatography (HPLC) and HPLC-mass spectrometry (MS). All millet varieties displayed effective radical and ROS inhibition activities, which generally positively correlated with phenolic contents, except for hydroxyl radical. HPLC analysis revealed the presence of ferulic and p-coumaric acids as major hydroxycinnamic acids in phenolic extract and responsible for the observed effects. Bound extracts of millet contributed 38-99% to ROS scavenging, depending on the variety and the test system employed. Hence, bound phenolics must be included in the evaluation of the antioxidant activity of millets and other cereals.

  8. Mitochondrial respiration deficits driven by reactive oxygen species in experimental temporal lobe epilepsy.

    PubMed

    Rowley, Shane; Liang, Li-Ping; Fulton, Ruth; Shimizu, Takahiko; Day, Brian; Patel, Manisha

    2015-03-01

    Metabolic alterations have been implicated in the etiology of temporal lobe epilepsy (TLE), but whether or not they have a functional impact on cellular energy producing pathways (glycolysis and/or oxidative phosphorylation) is unknown. The goal of this study was to determine if alterations in cellular bioenergetics occur using real-time analysis of mitochondrial oxygen consumption and glycolytic rates in an animal model of TLE. We hypothesized that increased steady-state levels of reactive oxygen species (ROS) initiated by epileptogenic injury result in impaired mitochondrial respiration. We established methodology for assessment of bioenergetic parameters in isolated synaptosomes from the hippocampus of Sprague-Dawley rats at various times in the kainate (KA) model of TLE. Deficits in indices of mitochondrial respiration were observed at time points corresponding with the acute and chronic phases of epileptogenesis. We asked if mitochondrial bioenergetic dysfunction occurred as a result of increased mitochondrial ROS and if it could be attenuated in the KA model by pharmacologically scavenging ROS. Increased steady-state ROS in mice with forebrain-specific conditional deletion of manganese superoxide dismutase (Sod2(fl/fl)NEX(Cre/Cre)) in mice resulted in profound deficits in mitochondrial oxygen consumption. Pharmacological scavenging of ROS with a catalytic antioxidant restored mitochondrial respiration deficits in the KA model of TLE. Together, these results demonstrate that mitochondrial respiration deficits occur in experimental TLE and ROS mechanistically contribute to these deficits. Furthermore, this study provides novel methodology for assessing cellular metabolism during the entire time course of disease development.

  9. Increased reactive oxygen species production during reductive stress: The roles of mitochondrial glutathione and thioredoxin reductases.

    PubMed

    Korge, Paavo; Calmettes, Guillaume; Weiss, James N

    2015-01-01

    Both extremes of redox balance are known to cause cardiac injury, with mounting evidence revealing that the injury induced by both oxidative and reductive stress is oxidative in nature. During reductive stress, when electron acceptors are expected to be mostly reduced, some redox proteins can donate electrons to O2 instead, which increases reactive oxygen species (ROS) production. However, the high level of reducing equivalents also concomitantly enhances ROS scavenging systems involving redox couples such as NADPH/NADP+ and GSH/GSSG. Here our objective was to explore how reductive stress paradoxically increases net mitochondrial ROS production despite the concomitant enhancement of ROS scavenging systems. Using recombinant enzymes and isolated permeabilized cardiac mitochondria, we show that two normally antioxidant matrix NADPH reductases, glutathione reductase and thioredoxin reductase, generate H2O2 by leaking electrons from their reduced flavoprotein to O2 when electron flow is impaired by inhibitors or because of limited availability of their natural electron acceptors, GSSG and oxidized thioredoxin. The spillover of H2O2 under these conditions depends on H2O2 reduction by peroxiredoxin activity, which may regulate redox signaling in response to endogenous or exogenous factors. These findings may explain how ROS production during reductive stress overwhelms ROS scavenging capability, generating the net mitochondrial ROS spillover causing oxidative injury. These enzymes could potentially be targeted to increase cancer cell death or modulate H2O2-induced redox signaling to protect the heart against ischemia/reperfusion damage.

  10. A Computational Model of Reactive Oxygen Species and Redox Balance in Cardiac Mitochondria

    PubMed Central

    Gauthier, Laura D.; Greenstein, Joseph L.; Cortassa, Sonia; O’Rourke, Brian; Winslow, Raimond L.

    2013-01-01

    Elevated levels of reactive oxygen species (ROS) play a critical role in cardiac myocyte signaling in both healthy and diseased cells. Mitochondria represent the predominant cellular source of ROS, specifically the activity of complexes I and III. The model presented here explores the modulation of electron transport chain ROS production for state 3 and state 4 respiration and the role of substrates and respiratory inhibitors. Model simulations show that ROS production from complex III increases exponentially with membrane potential (ΔΨm) when in state 4. Complex I ROS release in the model can occur in the presence of NADH and succinate (reverse electron flow), leading to a highly reduced ubiquinone pool, displaying the highest ROS production flux in state 4. In the presence of ample ROS scavenging, total ROS production is moderate in state 3 and increases substantially under state 4 conditions. The ROS production model was extended by combining it with a minimal model of ROS scavenging. When the mitochondrial redox status was oxidized by increasing the proton permeability of the inner mitochondrial membrane, simulations with the combined model show that ROS levels initially decline as production drops off with decreasing ΔΨm and then increase as scavenging capacity is exhausted. Hence, this mechanistic model of ROS production demonstrates how ROS levels are controlled by mitochondrial redox balance. PMID:23972856

  11. Fungal variegatic acid and extracellular polysaccharides promote the site-specific generation of reactive oxygen species.

    PubMed

    Zhu, Yuan; Mahaney, James; Jellison, Jody; Cao, Jinzhen; Gressler, Julia; Hoffmeister, Dirk; Goodell, Barry

    2017-03-01

    This study aims to clarify the role of variegatic acid (VA) in fungal attack by Serpula lacrymans, and also the generation and scavenging of reactive oxygen species (ROS) by the fungus. VA promotes a mediated Fenton reaction to generated ROS after oxalate solubilizes oxidized forms of iron. The fungal extracellular matrix (ECM) β-glucan scavenged ROS, and we propose this as a mechanism to protect the fungal hyphae while ROS generation is promoted to deconstruct the lignocellulose cell wall. A relatively high pH (4.4) also favored Fe(III) transfer from oxalate to VA as opposed to a lower pH (2.2) conditions, suggesting a pH-dependent Fe(III) transfer to VA employed by S. lacrymans. This permits ROS generation within the higher pH of the cell wall, while limiting ROS production near the fungal hyphae, while β-glucan from the fungal ECM scavenges ROS in the more acidic environments surrounding the fungal hyphae.

  12. Balancing the generation and elimination of reactive oxygen species

    USGS Publications Warehouse

    Rodriguez, Rusty; Redman, Regina

    2005-01-01

    Fossil records suggest that bacteria developed the ability to photosynthesize ≈3,500 million years ago (mya), initiating a very slow accumulation of atmospheric oxygen (1). Recent geochemical models suggest that atmospheric oxygen did not accumulate to levels conducive for aerobic life until 500–1,000 mya (2, 3). The oxygenation of Earth's atmosphere resulted in the emergence of aerobic organisms followed by a great diversification of biological species and the eventual evolution of humans.

  13. Reactive oxygen species production by catechol stabilized copper nanoparticles.

    PubMed

    Chen, Cheng; Ahmed, Ishtiaq; Fruk, Ljiljana

    2013-12-07

    Stable Cu nanoparticles (NPs) prepared using catechol containing dopamine-based linkers could generate reactive oxygen species (ROS) that can activate peroxidase enzymes and catalyze the degradation of fluorescent dye pollutants.

  14. The oxygen isotope equilibrium fractionation between sulfite species and water

    NASA Astrophysics Data System (ADS)

    Müller, Inigo A.; Brunner, Benjamin; Breuer, Christian; Coleman, Max; Bach, Wolfgang

    2013-11-01

    Sulfite is an important sulfoxy intermediate in oxidative and reductive sulfur cycling in the marine and terrestrial environment. Different aqueous sulfite species exist, such as dissolved sulfur dioxide (SO2), bisulfite (HSO3-), pyrosulfite (S2O52-) and sulfite sensu stricto (SO32-), whereas their relative abundance in solution depends on the concentration and the pH. Conversion of one species into another is rapid and involves in many cases incorporation of oxygen from, or release of oxygen to, water (e.g. SO2 + H2O ↔ HSO3- + H+), resulting in rapid oxygen isotope exchange between sulfite species and water. Consequently, the oxygen isotope composition of sulfite is strongly influenced by the oxygen isotope composition of water. Since sulfate does not exchange oxygen isotopes with water under most earth surface conditions, it can preserve the sulfite oxygen isotope signature that it inherits via oxidative and reductive sulfur cycling. Therefore, interpretation of δO values strongly hinges on the oxygen isotope equilibrium fractionation between sulfite and water which is poorly constrained. This is in large part due to technical difficulties in extraction of sulfite from solution for oxygen isotope analysis.

  15. [Formation of reactive oxygen species during pollen grain germination].

    PubMed

    Smirnova, A V; Matveeva, N P; Polesskaia, O G; Ermakov, I P

    2009-01-01

    The formation of reactive oxygen species in pollen at the early germination stage, which precedes the formation of the pollen tube, was studied. During this period, pollen grain is being hydrated, abruptly increasing its volume, and it passes from the resting state to active metabolism. Fluorescent methods have made it possible to reveal reactive oxygen species in the cytoplasm and inner layer of the pollen wall, intine. The cytoplasmic reactive oxygen species were mostly found in mitochondria, while extracellular ones were localized in aperture zones of intine, as well as in the solution surrounding pollen grains in vitro. The content of extracellular reactive oxygen species decreased after superoxide dismutase (100 units per ml) and diphenylene iodonium (100 microM), which indicates NADPH oxidase as one of possible producent of them. In conditions of suppression of extracellular reactive oxygen species production (100 microM diphenilene iodonium) or their promoted removal (after addition of 10 to 100 microM ascorbic acid), the number of germinating pollen grains increased. This effect disappeared after further increase in the concentration of the listed reagents. The result is evidence of the significance of processes of generation/removal of extracellular reactive oxygen species for pollen germination.

  16. KRIT1 Regulates the Homeostasis of Intracellular Reactive Oxygen Species

    PubMed Central

    Goitre, Luca; Balzac, Fiorella; Degani, Simona; Degan, Paolo; Marchi, Saverio; Pinton, Paolo; Retta, Saverio Francesco

    2010-01-01

    KRIT1 is a gene responsible for Cerebral Cavernous Malformations (CCM), a major cerebrovascular disease characterized by abnormally enlarged and leaky capillaries that predispose to seizures, focal neurological deficits, and fatal intracerebral hemorrhage. Comprehensive analysis of the KRIT1 gene in CCM patients has suggested that KRIT1 functions need to be severely impaired for pathogenesis. However, the molecular and cellular functions of KRIT1 as well as CCM pathogenesis mechanisms are still research challenges. We found that KRIT1 plays an important role in molecular mechanisms involved in the maintenance of the intracellular Reactive Oxygen Species (ROS) homeostasis to prevent oxidative cellular damage. In particular, we demonstrate that KRIT1 loss/down-regulation is associated with a significant increase in intracellular ROS levels. Conversely, ROS levels in KRIT1−/− cells are significantly and dose-dependently reduced after restoration of KRIT1 expression. Moreover, we show that the modulation of intracellular ROS levels by KRIT1 loss/restoration is strictly correlated with the modulation of the expression of the antioxidant protein SOD2 as well as of the transcriptional factor FoxO1, a master regulator of cell responses to oxidative stress and a modulator of SOD2 levels. Furthermore, we show that the KRIT1-dependent maintenance of low ROS levels facilitates the downregulation of cyclin D1 expression required for cell transition from proliferative growth to quiescence. Finally, we demonstrate that the enhanced ROS levels in KRIT1−/− cells are associated with an increased cell susceptibility to oxidative DNA damage and a marked induction of the DNA damage sensor and repair gene Gadd45α, as well as with a decline of mitochondrial energy metabolism. Taken together, our results point to a new model where KRIT1 limits the accumulation of intracellular oxidants and prevents oxidative stress-mediated cellular dysfunction and DNA damage by enhancing the

  17. KRIT1 regulates the homeostasis of intracellular reactive oxygen species.

    PubMed

    Goitre, Luca; Balzac, Fiorella; Degani, Simona; Degan, Paolo; Marchi, Saverio; Pinton, Paolo; Retta, Saverio Francesco

    2010-07-26

    KRIT1 is a gene responsible for Cerebral Cavernous Malformations (CCM), a major cerebrovascular disease characterized by abnormally enlarged and leaky capillaries that predispose to seizures, focal neurological deficits, and fatal intracerebral hemorrhage. Comprehensive analysis of the KRIT1 gene in CCM patients has suggested that KRIT1 functions need to be severely impaired for pathogenesis. However, the molecular and cellular functions of KRIT1 as well as CCM pathogenesis mechanisms are still research challenges. We found that KRIT1 plays an important role in molecular mechanisms involved in the maintenance of the intracellular Reactive Oxygen Species (ROS) homeostasis to prevent oxidative cellular damage. In particular, we demonstrate that KRIT1 loss/down-regulation is associated with a significant increase in intracellular ROS levels. Conversely, ROS levels in KRIT1(-/-) cells are significantly and dose-dependently reduced after restoration of KRIT1 expression. Moreover, we show that the modulation of intracellular ROS levels by KRIT1 loss/restoration is strictly correlated with the modulation of the expression of the antioxidant protein SOD2 as well as of the transcriptional factor FoxO1, a master regulator of cell responses to oxidative stress and a modulator of SOD2 levels. Furthermore, we show that the KRIT1-dependent maintenance of low ROS levels facilitates the downregulation of cyclin D1 expression required for cell transition from proliferative growth to quiescence. Finally, we demonstrate that the enhanced ROS levels in KRIT1(-/-) cells are associated with an increased cell susceptibility to oxidative DNA damage and a marked induction of the DNA damage sensor and repair gene Gadd45alpha, as well as with a decline of mitochondrial energy metabolism. Taken together, our results point to a new model where KRIT1 limits the accumulation of intracellular oxidants and prevents oxidative stress-mediated cellular dysfunction and DNA damage by enhancing the cell

  18. Reactive Oxygen Species Function to Mediate the Fe Deficiency Response in an Fe-Efficient Apple Genotype: An Early Response Mechanism for Enhancing Reactive Oxygen Production

    PubMed Central

    Sun, Chaohua; Wu, Ting; Zhai, Longmei; Li, Duyue; Zhang, Xinzhong; Xu, Xuefeng; Ma, Huiqin; Wang, Yi; Han, Zhenhai

    2016-01-01

    Reactive oxygen species (ROS) are important signaling molecules in plants that contribute to stress acclimation. This study demonstrated that ROS play a critical role in Fe deficiency-induced signaling at an early stage in Malus xiaojinensis. Once ROS production has been initiated, prolonged Fe starvation leads to activation of ROS scavenging mechanisms. Further, we demonstrated that ROS scavengers are involved in maintaining the cellular redox homeostasis during prolonged Fe deficiency treatment. Taken together, our results describe a feedback repression loop for ROS to preserve redox homeostasis and maintain a continuous Fe deficiency response in the Fe-efficient woody plant M. xiaojinensis. More broadly, this study reveals a new mechanism in which ROS mediate both positive and negative regulation of plant responses to Fe deficiency stress. PMID:27899933

  19. Reactive Oxygen Species Function to Mediate the Fe Deficiency Response in an Fe-Efficient Apple Genotype: An Early Response Mechanism for Enhancing Reactive Oxygen Production.

    PubMed

    Sun, Chaohua; Wu, Ting; Zhai, Longmei; Li, Duyue; Zhang, Xinzhong; Xu, Xuefeng; Ma, Huiqin; Wang, Yi; Han, Zhenhai

    2016-01-01

    Reactive oxygen species (ROS) are important signaling molecules in plants that contribute to stress acclimation. This study demonstrated that ROS play a critical role in Fe deficiency-induced signaling at an early stage in Malus xiaojinensis. Once ROS production has been initiated, prolonged Fe starvation leads to activation of ROS scavenging mechanisms. Further, we demonstrated that ROS scavengers are involved in maintaining the cellular redox homeostasis during prolonged Fe deficiency treatment. Taken together, our results describe a feedback repression loop for ROS to preserve redox homeostasis and maintain a continuous Fe deficiency response in the Fe-efficient woody plant M. xiaojinensis. More broadly, this study reveals a new mechanism in which ROS mediate both positive and negative regulation of plant responses to Fe deficiency stress.

  20. Contribution of reactive oxygen species to UV-B-induced damage in bacteria.

    PubMed

    Santos, Ana L; Gomes, Newton C M; Henriques, Isabel; Almeida, Adelaide; Correia, António; Cunha, Ângela

    2012-12-05

    The present work aimed to identify the reactive oxygen species (ROS) produced during UV-B exposure and their biochemical targets, in a set of bacterial isolates displaying different UV susceptibilities. For that, specific exogenous ROS scavengers (catalase/CAT, superoxide dismutase/SOD, sodium azide and mannitol) were used. Biological effects were assessed from total bacterial number, colony counts and heterotrophic activity (glucose uptake and respiration). DNA strand breakage, ROS generation, oxidative damage to proteins and lipids were used as markers of oxidative stress. Sodium azide conferred a statistically significant protection in terms of lipid oxidation and cell survival, suggesting that singlet oxygen might play an important role in UV-B induced cell inactivation. Mannitol exerted a significant protection against DNA strand breakage and protein carbonylation, assigning hydroxyl radicals to DNA and protein damage. The addition of exogenous CAT and SOD significantly protected the capacity for glucose uptake and respiration, suggesting that superoxide and H(2)O(2) are involved in the impairment of activity during UV-B exposure. The observation that amendment with ROS scavengers can sometimes also exert a pro-oxidant effect suggests that the intracellular oxidant status of the cell ultimately determines the efficiency of antioxidant defenses.

  1. Reactive oxygen species mediate phorbol ester-stimulated cAMP response in human eosinophils.

    PubMed

    Ezeamuzie, Charles I; Taslim, Najla

    2006-08-14

    Recently, we showed that phorbol 12-myristate 13-acetate (PMA) can cause a direct, PKC-dependent, stimulation of intracellular cAMP in human eosinophils. Since PMA also stimulates the release of reactive oxygen species in these cells, we have investigated whether reactive oxygen species are involved in the cAMP response. Provided eosinophils were incubated for <20 min at 37 degrees C before stimulation, PMA potently stimulated cAMP generation that surpassed that of histamine. Pre-treatment of the cells with the NADPH oxidase inhibitors, diphenyleneiodonium (DPI) and apocynin, strongly inhibited the cAMP production induced by PMA, but not that induced by histamine. This treatment also strongly inhibited the release of superoxide anions (O(2)(-)). The cAMP response was also inhibited by pre-treatment with the specific peroxide scavenger, ebselen, but not superoxide dismutase, or NG-nitro-l-arginine methyl ester (L-NAME), thus, suggesting the possible involvement of a peroxide rather than O(2)(-) or nitric oxide (NO). These results reveal a novel involvement of intracellular reactive oxygen species in protein kinase C (PKC)-dependent stimulation of cAMP production in human eosinophils.

  2. Inhibition of astrocyte glutamate uptake by reactive oxygen species: role of antioxidant enzymes.

    PubMed Central

    Sorg, O.; Horn, T. F.; Yu, N.; Gruol, D. L.; Bloom, F. E.

    1997-01-01

    BACKGROUND: The recent literature suggests that free radicals and reactive oxygen species may account for many pathologies, including those of the nervous system. MATERIALS AND METHODS: The influence of various reactive oxygen species on the rate of glutamate uptake by astrocytes was investigated on monolayers of primary cultures of mouse cortical astrocytes. RESULTS: Hydrogen peroxide and peroxynitrite inhibited glutamate uptake in a concentration-dependent manner. Addition of copper ions and ascorbate increased the potency and the efficacy of the hydrogen peroxide effect, supporting the potential neurotoxicity of the hydroxyl radical. The free radical scavenger dimethylthiourea effectively eliminated the inhibitory potential of a mixture containing hydrogen peroxide, copper sulphate, and ascorbate on the rate of glutamate transport into astrocytes. The inhibitory effect of hydrogen peroxide on glutamate uptake was not altered by the inhibition of glutathione peroxidase, whereas the inhibition of catalase by sodium azide clearly potentiated this effect. Superoxide and nitric oxide had no effect by themselves on the rate of glutamate uptake by astrocytes. The absence of an effect of nitric oxide is not due to an inability of astrocytes to respond to this substance, since the same cultures did respond to nitric oxide with a sustained increase in cytoplasmic free calcium. CONCLUSION: These results confirm that reactive oxygen species have a potential neurotoxicity by means of impairing glutamate transport into astrocytes, and they suggest that preventing the accumulation of hydrogen peroxide in the extracellular space of the brain, especially during conditions that favor hydroxyl radical formation, could be therapeutic. PMID:9260155

  3. Sulfhydryl protection and the oxygen effect on radiation-induced inactivation of r-chromatin in vitro. Influence of an OH scavenger: t-butanol

    SciTech Connect

    Herskind, C.

    1988-07-01

    Transcriptionally active r-chromatin from Tetrahymena has been irradiated in dilute phosphate buffer, pH 7.2, in the presence of the sulfhydryl compound 2-mercaptoethanol (MSH). MSH was more protective against radiation-induced inactivation of transcription under N/sub 2/ than under O/sub 2/. The OH scavenger, t-butanol, on the other hand, gives significantly less protection under N/sub 2/ than under O/sub 2/, apparently due to inactivation by secondary t-butanol radicals under anoxia as shown previously. However, MSH was found to restore most of the protective effect of t-butanol under N/sub 2/. Inactivation was studied as a function of MSH concentration (0.03-10 mM) at different, fixed concentrations of t-butanol (3-300 mM). The observed protection may be explained essentially in terms of (1) OH scavenging, (2) repair of DNA radicals by H-atom transfer from MSH under N/sub 2/ in competition with fixation of damage under O/sub 2/, and (3) protection against inactivation by secondary t-butanol radicals by H-atom transfer to these radicals. The sensitizing effect of oxygen in the presence of MSH is reduced by t-butanol and may even be reversed to produce an apparently protective effect. This finding is discussed in terms of residual inactivation by secondary radicals. The significance of OH scavengers as potential modifiers of oxygen enhancement ratio values is discussed.

  4. Role of 5-aminolevulinic acid (ALA) on active oxygen-scavenging system in NaCl-treated spinach (Spinacia oleracea).

    PubMed

    Nishihara, Eiji; Kondo, Kensuke; Parvez, Mohammad Masud; Takahashi, Kuniaki; Watanabe, Keitaro; Tanaka, Kiyoshi

    2003-09-01

    ALA is a key precursor in the biosynthesis of porphyrins such as chlorophyll and heme, and was found to induce temporary elevations in the photosynthesis rate, APX, and CAT; furthermore, treatment with ALA at a low concentration might be correlated to the increase of NaCl tolerance of spinach plants. The photosynthetic rate and the levels of active oxygen-scavenging system in the 3rd leaf of spinach (Spinacia oleracea) plants grown by foliar treatment with 0, 0.18, 0.60 and 1.80 mmol/L 5-aminolevulinic acid under 50 and 100 mmol/L NaCl were analyzed. Plants treated with 0.60 and 1.80 mmol/L ALA showed significant increases in the photosynthetic rate at 50 and 100 mmol/L NaCl, while that of 0.18 mmol/L ALA did not show any changes at 50 mmol/L NaCl and a gradual decrease at 100 mmol/L NaCl. In contrast, the rate with 0 mmol/L ALA showed reduction at both concentrations of NaCl. The increase of hydrogen peroxide content by treatment with 0.60 and 1.80 mmol/L ALA were more controlled than that of 0 mmol/L ALA under both NaCl conditions. These ALA-treated spinach leaves also exhibited a lower oxidized/reduced ascorbate acid ratio and a higher reduced/oxidized glutathione ratio than the 0 mmol/L-treated spinach leaves when grown at both NaCl conditions. With regard to the antioxidant enzyme activities in the leaves, ascorbate peroxidase, catalase, and glutathione reductase activities were enhanced remarkably, most notably at day 3, by treatment with 0.60 and 1.80 mmol/L ALA under both NaCl conditions in comparison to that of 0 and 0.18 mmol/L ALA. These data indicate that the protection against oxidative damage by higher levels of antioxidants and enzyme activities, and by a more active ascorbate-glutathione cycle related to the increase of the photosynthesis rate, could be involved in the increased salt tolerance observed in spinach by treatment with 0.60 to 1.80 mmol/L ALA with NaCl.

  5. Generation of reactive oxygen species by the faecal matrix

    PubMed Central

    Owen, R; Spiegelhalder, B; Bartsch, H

    2000-01-01

    BACKGROUND—Reactive oxygen species are implicated in the aetiology of a range of human diseases and there is increasing interest in their role in the development of cancer.
AIM—To develop a suitable method for the detection of reactive oxygen species produced by the faecal matrix.
METHODS—A refined high performance liquid chromatography system for the detection of reactive oxygen species is described.
RESULTS—The method allows baseline separation of the products of hydroxyl radical attack on salicylic acid in the hypoxanthine/xanthine oxidase system, namely 2,5-dihydroxybenzoic acid, 2,3-dihydroxybenzoic acid, and catechol. The increased efficiency and precision of the method has allowed a detailed evaluation of the dynamics of reactive oxygen species generation in the faecal matrix. The data show that the faecal matrix is capable of generating reactive oxygen species in abundance. This ability cannot be attributed to the bacteria present, but rather to a soluble component within the matrix. As yet, the nature of this soluble factor is not entirely clear but is likely to be a reducing agent.
CONCLUSIONS—The soluble nature of the promoting factor renders it amenable to absorption, and circumstances may exist in which either it comes into contact with either free or chelated iron in the colonocyte, leading to direct attack on cellular DNA, or else it initiates lipid peroxidation processes whereby membrane polyunsaturated fatty acids are attacked by reactive oxygen species propagating chain reactions leading to the generation of promutagenic lesions such as etheno based DNA adducts.


Keywords: colorectal cancer; faecal matrix; hypoxanthine; phytic acid; reactive oxygen species; xanthine oxidase PMID:10644317

  6. Direct observation of both contact and remote oxygen scavenging of GeO{sub 2} in a metal-oxide-semiconductor stack

    SciTech Connect

    Fadida, S. Shekhter, P.; Eizenberg, M.; Cvetko, D.; Floreano, L.; Verdini, A.; Kymissis, I.

    2014-10-28

    In the path to incorporating Ge based metal-oxide-semiconductor into modern nano-electronics, one of the main issues is the oxide-semiconductor interface quality. Here, the reactivity of Ti on Ge stacks and the scavenging effect of Ti were studied using synchrotron X-ray photoelectron spectroscopy measurements, with an in-situ metal deposition and high resolution transmission electron microscopy imaging. Oxygen removal from the Ge surface was observed both in direct contact as well as remotely through an Al{sub 2}O{sub 3} layer. The scavenging effect was studied in situ at room temperature and after annealing. We find that the reactivity of Ti can be utilized for improved scaling of Ge based devices.

  7. Shelf life of case-ready beef steaks (Semitendinosus muscle) stored in oxygen-depleted master bag system with oxygen scavengers and CO2/N2 modified atmosphere packaging.

    PubMed

    Limbo, S; Uboldi, E; Adobati, A; Iametti, S; Bonomi, F; Mascheroni, E; Santagostino, S; Powers, T H; Franzetti, L; Piergiovanni, L

    2013-03-01

    This study aims to evaluate the stability of beef from Semitendinosus muscle packaged in oxygen permeable wrapped-tray units and stored in a master bag system, with and without oxygen scavengers. Changes in the atmosphere composition, microbiological indexes, myoglobin forms and color parameters were monitored during the storage in master bag, blooming and display life. The presence of scavengers reduced rapidly the oxygen concentration and maintained it at values not detectable instrumentally. Within few days of storage in master bags, the resolution of the transient discoloration was completed and the meat quality was maintained over the anoxic storage. After the removal from master bags meat bloomed completely reaching OxyMb level and Chroma values higher than those on fresh meat at t(0). During 48 h of display life at 4 °C, quality attributes had a decay slower than samples stored traditionally in air. Without scavengers the oxygen caused the irreversible discoloration within 7 days, due to the formation of metmyoglobin on the surface.

  8. Total phenolic content, radical scavenging properties, and essential oil composition of Origanum species from different populations.

    PubMed

    Dambolena, José S; Zunino, María P; Lucini, Enrique I; Olmedo, Rubén; Banchio, Erika; Bima, Paula J; Zygadlo, Julio A

    2010-01-27

    The aim of this work was to compare the antiradical activity, total phenol content (TPC), and essential oil composition of Origanum vulgare spp. virens, Origanum x applii, Origanum x majoricum, and O. vulgare spp. vulgare cultivated in Argentina in different localities. The experiment was conducted in the research station of La Consulta (INTA-Mendoza), the research station of Santa Lucia (INTA-San Juan), and Agronomy Faculty of National University of La Pampa, from 2007 to 2008. The composition of the essential oils of oregano populations was independent of cultivation conditions. In total, 39 compounds were identified in essential oils of oregano from Argentina by means of GC-MS. Thymol and trans-sabinene hydrate were the most prominent compounds, followed by gamma-terpinene, terpinen-4-ol, and alpha-terpinene. O. vulgare vulgare is the only Origanum studied which is rich in gamma-terpinene. Among tested oregano, O. x majoricum showed the highest essential oil content, 3.9 mg g(-1) dry matter. The plant extract of O. x majoricum had greater total phenol content values, 19.36 mg/g dry weight, than the rest of oregano studied. To find relationships among TPC, free radical scavenging activity (FRSA), and climate variables, canonical correlations were calculated. The results obtained allow us to conclude that 70% of the TPC and FRSA variability can be explained by the climate variables (R(2) = 0.70; p = 8.3 x 10(-6)), the temperature being the most important climatic variable.

  9. pH dependent catalytic activities of platinum nanoparticles with respect to the decomposition of hydrogen peroxide and scavenging of superoxide and singlet oxygen

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Wu, Haohao; Li, Meng; Yin, Jun-Jie; Nie, Zhihong

    2014-09-01

    Recently, platinum (Pt) nanoparticles (NPs) have received increasing attention in the field of catalysis and medicine due to their excellent catalytic activity. To rationally design Pt NPs for these applications, it is crucial to understand the mechanisms underlying their catalytic and biological activities. This article describes a systematic study on the Pt NP-catalyzed decomposition of hydrogen peroxide (H2O2) and scavenging of superoxide (O2&z.rad;-) and singlet oxygen (1O2) over a physiologically relevant pH range of 1.12-10.96. We demonstrated that the catalytic activities of Pt NPs can be modulated by the pH value of the environment. Our results suggest that Pt NPs possess peroxidase-like activity of decomposing H2O2 into &z.rad;OH under acidic conditions, but catalase-like activity of producing H2O and O2 under neutral and alkaline conditions. In addition, Pt NPs exhibit significant superoxide dismutase-like activity of scavenging O2&z.rad;- under neutral conditions, but not under acidic conditions. The 1O2 scavenging ability of Pt NPs increases with the increase in the pH of the environment. The study will provide useful guidance for designing Pt NPs with desired catalytic and biological properties.Recently, platinum (Pt) nanoparticles (NPs) have received increasing attention in the field of catalysis and medicine due to their excellent catalytic activity. To rationally design Pt NPs for these applications, it is crucial to understand the mechanisms underlying their catalytic and biological activities. This article describes a systematic study on the Pt NP-catalyzed decomposition of hydrogen peroxide (H2O2) and scavenging of superoxide (O2&z.rad;-) and singlet oxygen (1O2) over a physiologically relevant pH range of 1.12-10.96. We demonstrated that the catalytic activities of Pt NPs can be modulated by the pH value of the environment. Our results suggest that Pt NPs possess peroxidase-like activity of decomposing H2O2 into &z.rad;OH under acidic conditions

  10. Species delimitation in northern European water scavenger beetles of the genus Hydrobius (Coleoptera, Hydrophilidae).

    PubMed

    Fossen, Erlend I; Ekrem, Torbjørn; Nilsson, Anders N; Bergsten, Johannes

    2016-01-01

    The chiefly Holarctic Hydrobius species complex (Coleoptera, Hydrophilidae) currently consists of Hydrobius arcticus Kuwert, 1890, and three morphological variants of Hydrobius fuscipes (Linnaeus, 1758): var. fuscipes, var. rottenbergii and var. subrotundus in northern Europe. Here molecular and morphological data are used to test the species boundaries in this species complex. Three gene segments (COI, H3 and ITS2) were sequenced and analyzed with Bayesian methods to infer phylogenetic relationships. The Generalized Mixed Yule Coalescent (GMYC) model and two versions of the Bayesian species delimitation method BPP, with or without an a priori defined guide tree (v2.2 & v3.0), were used to evaluate species limits. External and male genital characters of primarily Fennoscandian specimens were measured and statistically analyzed to test for significant differences in quantitative morphological characters. The four morphotypes formed separate genetic clusters on gene trees and were delimited as separate species by GMYC and by both versions of BPP, despite specimens of Hydrobius fuscipes var. fuscipes and Hydrobius fuscipes var. subrotundus being sympatric. Hydrobius arcticus and Hydrobius fuscipes var. rottenbergii could only be separated genetically with ITS2, and were delimited statistically with GMYC on ITS2 and with BPP on the combined data. In addition, six or seven potentially cryptic species of the Hydrobius fuscipes complex from regions outside northern Europe were delimited genetically. Although some overlap was found, the mean values of six male genital characters were significantly different between the morphotypes (p < 0.001). Morphological characters previously presumed to be diagnostic were less reliable to separate Hydrobius fuscipes var. fuscipes from Hydrobius fuscipes var. subrotundus, but characters in the literature for Hydrobius arcticus and Hydrobius fuscipes var. rottenbergii were diagnostic. Overall, morphological and molecular evidence

  11. Reactive oxygen species: role in the development of cancer and various chronic conditions

    PubMed Central

    Waris, Gulam; Ahsan, Haseeb

    2006-01-01

    Oxygen derived species such as superoxide radical, hydrogen peroxide, singlet oxygen and hydroxyl radical are well known to be cytotoxic and have been implicated in the etiology of a wide array of human diseases, including cancer. Various carcinogens may also partly exert their effect by generating reactive oxygen species (ROS) during their metabolism. Oxidative damage to cellular DNA can lead to mutations and may, therefore, play an important role in the initiation and progression of multistage carcinogenesis. The changes in DNA such as base modification, rearrangement of DNA sequence, miscoding of DNA lesion, gene duplication and the activation of oncogenes may be involved in the initiation of various cancers. Elevated levels of ROS and down regulation of ROS scavengers and antioxidant enzymes are associated with various human diseases including various cancers. ROS are also implicated in diabtes and neurodegenerative diseases. ROS influences central cellular processes such as proliferation a, apoptosis, senescence which are implicated in the development of cancer. Understanding the role of ROS as key mediators in signaling cascades may provide various opportunities for pharmacological intervention. PMID:16689993

  12. A comparative kinetic and mechanistic study between tetrahydrozoline and naphazoline toward photogenerated reactive oxygen species.

    PubMed

    Criado, Susana; García, Norman A

    2010-01-01

    Kinetic and mechanistic aspects of the vitamin B2 (riboflavin [Rf])-sensitized photo-oxidation of the imidazoline derivates (IDs) naphazoline (NPZ) and tetrahydrozoline (THZ) were investigated in aqueous solution. The process appears as important on biomedical grounds, considering that the vitamin is endogenously present in humans, and IDs are active components of ocular medicaments of topical application. Under aerobic visible light irradiation, a complex picture of competitive interactions between sensitizer, substrates and dissolved oxygen takes place: the singlet and triplet ((3)Rf*) excited states of Rf are quenched by the IDs: with IDs concentrations ca. 5.0 mM and 0.02 mM Rf, (3)Rf* is quenched by IDs, in a competitive fashion with dissolved ground state oxygen. Additionally, the reactive oxygen species: O(2)((1)Delta(g)), O(2)(*-), HO(*) and H(2)O(2), generated from (3)Rf* and Rf(*-), were detected with the employment of time-resolved methods or specific scavengers. Oxygen uptake experiments indicate that, for NPZ, only H(2)O(2) was involved in the photo-oxidation. In the case of THZ, O(2)(*-), HO(*) and H(2)O(2) were detected, whereas only HO(*) was unambiguously identified as THZ oxidative agents. Upon direct UV light irradiation NPZ and THZ generate O(2)((1)Delta(g)), with quantum yields of 0.2 (literature value, employed as a reference) and 0.08, respectively, in acetonitrile.

  13. Condensational growth and trace species scavenging in stratospheric sulfuric acid/water aerosol droplets

    NASA Technical Reports Server (NTRS)

    Tompson, Robert V., Jr.

    1991-01-01

    Stratospheric aerosols play a significant role in the environment. The composition of aerosols is believed to be a liquid solution of sulfuric acid and water with numerous trace species. Of these trace species, ozone in particular was recognized as being very important in its role of shielding the environment from harmful ultraviolet radiation. Also among the trace species are HCl and ClONO2, the so called chlorine reservoir species and various oxides of nitrogen. The quantity of stratospheric aerosol and its particle size distribution determines, to a large degree, the chemistry present in the stratosphere. Aerosols experience 3 types of growth: nucleation, condensation, and coagulation. The application of condensation investigations to the specific problem of stratospheric aerosols is discussed.

  14. The French Paradox: Determining the Superoxide-Scavenging Capacity of Red Wine and Other Beverages

    ERIC Educational Resources Information Center

    Logan, Barry A.; Hammond, Matthew P.; Stormo, Benjamin M.

    2008-01-01

    Plant-derived phenolic compounds such as those found in red wine, tea, and certain fruit juices may protect against cardiovascular disease by detoxifying (scavenging) superoxide and other unstable reactive oxygen species. We present a laboratory exercise that can be used to assess the superoxide-scavenging capacity of beverages. Among the…

  15. Species delimitation in northern European water scavenger beetles of the genus Hydrobius (Coleoptera, Hydrophilidae)

    PubMed Central

    Fossen, Erlend I.; Ekrem, Torbjørn; Nilsson, Anders N.; Bergsten, Johannes

    2016-01-01

    Abstract The chiefly Holarctic Hydrobius species complex (Coleoptera, Hydrophilidae) currently consists of Hydrobius arcticus Kuwert, 1890, and three morphological variants of Hydrobius fuscipes (Linnaeus, 1758): var. fuscipes, var. rottenbergii and var. subrotundus in northern Europe. Here molecular and morphological data are used to test the species boundaries in this species complex. Three gene segments (COI, H3 and ITS2) were sequenced and analyzed with Bayesian methods to infer phylogenetic relationships. The Generalized Mixed Yule Coalescent (GMYC) model and two versions of the Bayesian species delimitation method BPP, with or without an a priori defined guide tree (v2.2 & v3.0), were used to evaluate species limits. External and male genital characters of primarily Fennoscandian specimens were measured and statistically analyzed to test for significant differences in quantitative morphological characters. The four morphotypes formed separate genetic clusters on gene trees and were delimited as separate species by GMYC and by both versions of BPP, despite specimens of Hydrobius fuscipes var. fuscipes and Hydrobius fuscipes var. subrotundus being sympatric. Hydrobius arcticus and Hydrobius fuscipes var. rottenbergii could only be separated genetically with ITS2, and were delimited statistically with GMYC on ITS2 and with BPP on the combined data. In addition, six or seven potentially cryptic species of the Hydrobius fuscipes complex from regions outside northern Europe were delimited genetically. Although some overlap was found, the mean values of six male genital characters were significantly different between the morphotypes (p < 0.001). Morphological characters previously presumed to be diagnostic were less reliable to separate Hydrobius fuscipes var. fuscipes from Hydrobius fuscipes var. subrotundus, but characters in the literature for Hydrobius arcticus and Hydrobius fuscipes var. rottenbergii were diagnostic. Overall, morphological and molecular

  16. Comparison of two strategies for detection of reactive oxygen species

    NASA Astrophysics Data System (ADS)

    Gao, Weidong; Zhou, Yuanshu; Gu, Yueqing

    2014-09-01

    Photodynamic therapy (PDT) is a clinically approved treatment that was applied to oncology , dermatology, and ophthalmology. Reactive oxygen species (ROS) play a important role in the efficacy of PDT. Online monitoring of reactive oxygen species is the key to understand effect of PDT treatment. We used Fluorescence probes DPBF and luminescent probe luminal to measure the ROS in cells. And we revaluate the relationship between the amount of light and cell survival. There is strongly correlated between the amount of light and cell kill.

  17. Reactive oxygen species production by catechol stabilized copper nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Cheng; Ahmed, Ishtiaq; Fruk, Ljiljana

    2013-11-01

    Stable Cu nanoparticles (NPs) prepared using catechol containing dopamine-based linkers could generate reactive oxygen species (ROS) that can activate peroxidase enzymes and catalyze the degradation of fluorescent dye pollutants.Stable Cu nanoparticles (NPs) prepared using catechol containing dopamine-based linkers could generate reactive oxygen species (ROS) that can activate peroxidase enzymes and catalyze the degradation of fluorescent dye pollutants. Electronic supplementary information (ESI) available: Details of the synthesis of dopamine linkers and Cu NPs, peroxidase activity tests, H2O2 calibration and degradation tests for resorufin, RB and MB. See DOI: 10.1039/c3nr03563h

  18. Role of reactive oxygen species in myocardial remodeling.

    PubMed

    Zhang, Min; Shah, Ajay M

    2007-03-01

    Adverse cardiac remodeling is a fundamental process in the progression to chronic heart failure. Although the mechanisms underlying cardiac remodeling are multi-factorial, a significant body of evidence points to the crucial roles of increased reactive oxygen species. This article reviews recent advances in delineating the different sources of production for reactive oxygen species (namely mitochondria, xanthine oxidase, uncoupled nitric oxide synthases, and NADPH oxidases) that may be involved in cardiac remodeling and the aspects of the remodeling process that they affect. These data could suggest new ways of targeting redox pathways for the prevention and treatment of adverse cardiac remodeling.

  19. Endothelial GRK2 regulates vascular homeostasis through the control of free radical oxygen species

    PubMed Central

    Ciccarelli, Michele; Sorriento, Daniela; Franco, Antonietta; Fusco, Anna; Giudice, Carmine Del; Annunziata, Roberto; Cipolletta, Ersilia; Monti, Maria Gaia; Dorn, Gerald W; Trimarco, Bruno; Iaccarino, Guido

    2014-01-01

    Objective The role of endothelial GRK2 was investigated in mice with selective deletion of the kinase in the endothelium (Tie2-CRE/GRK2fl/fl). Approach and Results Aortas from Tie2-CRE/GRK2fl/fl presented functional and structural alterations as compared to control GRK2fl/fl mice. In particular, vasoconstriction was blunted to different agonists, and collagen and elastic rearrangement and macrophage infiltration were observed. In primary cultured endothelial cells deficient for GRK2, mitochondrial reactive oxygen species (ROS) was increased, leading to expression of cytokines. Chronic treatment with a ROS scavenger in mice corrected the vascular phenotype by recovering vasoconstriction, structural abnormalities and reducing macrophage infiltration. Conclusions These results demonstrate that GRK2 removal compromises vascular phenotype and integrity by increasing endothelial ROS production. PMID:23950144

  20. Balance of nitric oxide and reactive oxygen species in myocardial reperfusion injury and protection.

    PubMed

    Folino, Anna; Losano, Gianni; Rastaldo, Raffaella

    2013-12-01

    Depending on their concentrations, both nitric oxide (NO) and reactive oxygen species (ROS) take part either in myocardial ischemia reperfusion injury or in protection by ischemic and pharmacological preconditioning (Ipre) and postconditioning (Ipost). At the beginning of reperfusion, a transient release of NO is promptly scavenged by ROS to form the highly toxic peroxynitrite, which is responsible for a further increase of ROS through endothelial nitric oxide synthase uncoupling. The protective role of NO has suggested the use of NO donors to mimic Ipre and Ipost. However, NO donors have not always given the expected protection, possibly because they are responsible for the production of different amounts of ROS that depend on the amount of released NO. This review is focused on the role of the balance of NO and ROS in myocardial injury and its prevention by Ipre and Ipost and after the use of NO donors given with or without antioxidant compounds to mimic Ipre and Ipost.

  1. Catalytic Coupling of Oxidative Phosphorylation, ATP Demand, and Reactive Oxygen Species Generation

    PubMed Central

    Bazil, Jason N.; Beard, Daniel A.; Vinnakota, Kalyan C.

    2016-01-01

    Competing models of mitochondrial energy metabolism in the heart are highly disputed. In addition, the mechanisms of reactive oxygen species (ROS) production and scavenging are not well understood. To deepen our understanding of these processes, a computer model was developed to integrate the biophysical processes of oxidative phosphorylation and ROS generation. The model was calibrated with experimental data obtained from isolated rat heart mitochondria subjected to physiological conditions and workloads. Model simulations show that changes in the quinone pool redox state are responsible for the apparent inorganic phosphate activation of complex III. Model simulations predict that complex III is responsible for more ROS production during physiological working conditions relative to complex I. However, this relationship is reversed under pathological conditions. Finally, model analysis reveals how a highly reduced quinone pool caused by elevated levels of succinate is likely responsible for the burst of ROS seen during reperfusion after ischemia. PMID:26910433

  2. The Role of Mitochondria in Reactive Oxygen Species Metabolism and Signaling

    PubMed Central

    Starkov, Anatoly A.

    2010-01-01

    Oxidative stress is considered a major contributor to the etiology of both “normal” senescence and severe pathologies with serious public health implications. Several cellular sources, including mitochondria, are known to produce significant amounts of reactive oxygen species (ROS) that may contribute to intracellular oxidative stress. Mitochondria possess at least 10 known sites that are capable of generating ROS, but they also feature a sophisticated multilayered ROS defense system that is much less studied. This review summarizes the current knowledge about major components involved in mitochondrial ROS metabolism and factors that regulate ROS generation and removal at the level of mitochondria. An integrative systemic approach is applied to analysis of mitochondrial ROS metabolism, which is “dissected” into ROS generation, ROS emission, and ROS scavenging. The in vitro ROS-producing capacity of several mitochondrial sites is compared in the metabolic context and the role of mitochondria in ROS-dependent intracellular signaling is discussed. PMID:19076429

  3. The regulatory roles of ethylene and reactive oxygen species (ROS) in plant salt stress responses.

    PubMed

    Zhang, Ming; Smith, J Andrew C; Harberd, Nicholas P; Jiang, Caifu

    2016-08-01

    Soil salinity is one of the most commonly encountered environmental stresses affecting plant growth and crop productivity. Accordingly, plants have evolved a variety of morphological, physiological and biochemical strategies that enable them to adapt to saline growth conditions. For example, it has long been known that salinity-stress increases both the production of the gaseous stress hormone ethylene and the in planta accumulation of reactive oxygen species (ROS). Recently, there has been significant progress in understanding how the fine-tuning of ethylene biosynthesis and signaling transduction can promote salinity tolerance, and how salinity-induced ROS accumulation also acts as a signal in the mediation of salinity tolerance. Furthermore, recent advances have indicated that ethylene signaling modulates salinity responses largely via regulation of ROS-generating and ROS-scavenging mechanisms. This review focuses on these recent advances in understanding the linked roles of ethylene and ROS in salt tolerance.

  4. Electrochemical oxidation of pyrogallol: formation and characterization of long-lived oxygen radicals and application to assess the radical scavenging abilities of antioxidants.

    PubMed

    Mu, Shaolin; Chen, Chong

    2012-10-18

    Electrochemical oxidation of pyrogallol in a pH 5.0 phosphate buffer was carried out on a reduced graphene oxide/glassy carbon (RGO/GC) electrode. Reduced graphene oxide plays an important role in catalyzing the electrochemical oxidation of pyrogallol. A deep yellow film deposited on the electrode exhibits electroactivity in a wide pH range. On the basis of the experimental results from measurements of (1)H NMR, (13)C NMR, and IR spectra, there are hydroxyl, carbonyl, and aldehyde groups in the product. No visible absorption peak occurs in the UV-vis spectrum of the product, and its molecular weight is lower than that of the dipolymer but higher than that of the monomer. Therefore, the film is neither a polymer nor a dipolymer and is only a product of pyrogallol oxidation with oxygen radicals. No tendency toward the decay of the ESR signal intensity of the electrogenerated film deposited on the RGO/graphite electrode was observed after 210 days. Electrogenerated film was used as a radical source to test the radical scavenging abilities of ascorbic acid, catechin, and catechol in aqueous solutions based on the ESR signal intensity. The result indicates that ascorbic acid and catechin can scavenge the free radicals, but catechol can hardly scavenge the free radicals.

  5. pH dependent catalytic activities of platinum nanoparticles with respect to the decomposition of hydrogen peroxide and scavenging of superoxide and singlet oxygen.

    PubMed

    Liu, Yi; Wu, Haohao; Li, Meng; Yin, Jun-Jie; Nie, Zhihong

    2014-10-21

    Recently, platinum (Pt) nanoparticles (NPs) have received increasing attention in the field of catalysis and medicine due to their excellent catalytic activity. To rationally design Pt NPs for these applications, it is crucial to understand the mechanisms underlying their catalytic and biological activities. This article describes a systematic study on the Pt NP-catalyzed decomposition of hydrogen peroxide (H2O2) and scavenging of superoxide (O2˙(-)) and singlet oxygen ((1)O2) over a physiologically relevant pH range of 1.12-10.96. We demonstrated that the catalytic activities of Pt NPs can be modulated by the pH value of the environment. Our results suggest that Pt NPs possess peroxidase-like activity of decomposing H2O2 into ˙OH under acidic conditions, but catalase-like activity of producing H2O and O2 under neutral and alkaline conditions. In addition, Pt NPs exhibit significant superoxide dismutase-like activity of scavenging O2˙(-) under neutral conditions, but not under acidic conditions. The (1)O2 scavenging ability of Pt NPs increases with the increase in the pH of the environment. The study will provide useful guidance for designing Pt NPs with desired catalytic and biological properties.

  6. A novel nematode effector suppresses plant immunity by activating host reactuve oxygen species-scavenging system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oxidative burst is a hallmark event of the pathogen-associated molecular pattern (PAMP) triggered immunity (PTI), which is the first line of plant defense mechanisms, but it remains unclear how nematodes can overcome this defense mechanism. In this study, we show that plant-parasitic nematode Meloid...

  7. Spectroscopically Characterized Synthetic Mononuclear Nickel-Oxygen Species.

    PubMed

    Corona, Teresa; Company, Anna

    2016-09-12

    Iron, copper, and manganese are the predominant metals found in oxygenases that perform efficient and selective hydrocarbon oxidations and for this reason, a large number of the corresponding metal-oxygen species has been described. However, in recent years nickel has been found in the active site of enzymes involved in oxidation processes, in which nickel-dioxygen species are proposed to play a key role. Owing to this biological relevance and to the existence of different catalytic protocols that involve the use of nickel catalysts in oxidation reactions, there is a growing interest in the detection and characterization of nickel-oxygen species relevant to these processes. In this Minireview the spectroscopically/structurally characterized synthetic superoxo, peroxo, and oxonickel species that have been reported to date are described. From these studies it becomes clear that nickel is a very promising metal in the field of oxidation chemistry with still unexplored possibilities.

  8. Kinetics of oxygen species in an electrically driven singlet oxygen generator

    NASA Astrophysics Data System (ADS)

    Azyazov, V. N.; Torbin, A. P.; Pershin, A. A.; Mikheyev, P. A.; Heaven, M. C.

    2015-12-01

    The kinetics of oxygen species in the gaseous medium of a discharge singlet oxygen generator has been revisited. Vibrationally excited ozone O3(υ) formed in O + O2 recombination is thought to be a significant agent in the deactivation of singlet oxygen O2(a1Δ), oxygen atom removal and ozone formation. It is shown that the process O3(υ ⩾ 2) + O2(a1Δ) → 2O2 + O is the main O2(a1Δ) deactivation channel in the post-discharge zone. If no measures are taken to decrease the oxygen atom concentration, the contribution of this process to the overall O2(a1Δ) removal is significant, even in the discharge zone. A simplified model for the kinetics of vibrationally excited ozone is proposed. Calculations based on this model yield results that are in good agreement with the experimental data.

  9. H2S cytotoxicity mechanism involves reactive oxygen species formation and mitochondrial depolarisation.

    PubMed

    Eghbal, Mohammad A; Pennefather, Peter S; O'Brien, Peter J

    2004-10-15

    A number of scavengers of reactive oxygen species (ROS) were found to be protective against cell death induced by hydrogen sulfide (H2S) in isolated hepatocytes. The H2O2 scavengers alpha-ketoglutarate and pyruvate, which also act as energy substrate metabolites, were more protective against H2S toxicity than lactate which is only an energy substrate metabolite. All of these results suggest that H2S toxicity is dependent on ROS production. We measured ROS formation directly in hepatocytes using the fluorogenic dichlorofluorescin method. H2S-induced ROS formation was dose dependent and pyruvate inhibited this ROS production. Non-toxic concentrations of H2S enhanced the cytotoxicity of H2O2 generated by glucose/glucose oxidase, which was inhibited by CYP450 inibitors. Furthermore, hepatocyte ROS formation induced by H2S was decreased by CYP450 inhibitors cimetidine and benzylimidazole. These results suggest that CYP450-dependant metabolism of H2S is responsible for inducing ROS production. H2S-induced cytotoxicity was preceded by mitochondrial depolarization as measured by rhodamine 123 fluorescence. Mitochondrial depolarization induced by H2S was prevented by zinc, methionine and pyruvate all of which decreased H2S-induced cell death. Treatment of H2S poisoning may benefit from interventions aimed at minimizing ROS-induced damage and reducing mitochondrial damage.

  10. Nitric Oxide and Reactive Oxygen Species Mediate Metabolic Changes in Barley Seed Embryo during Germination

    PubMed Central

    Ma, Zhenguo; Marsolais, Frédéric; Bykova, Natalia V.; Igamberdiev, Abir U.

    2016-01-01

    The levels of nitric oxide (NO) and reactive oxygen species (ROS), ATP/ADP ratios, reduction levels of ascorbate and glutathione, expression of the genes encoding proteins involved in metabolism of NO and activities of the enzymes involved in fermentation and in metabolism of NO and ROS were studied in the embryos of germinating seeds of two barley (Hordeum vulgare L.) cultivars differing in dormancy level. The level of NO production continuously increased after imbibition while the level of nitrosylated SH-groups in proteins increased. This corresponded to the decrease of free SH-groups in proteins. At early stage of germination (0–48 h post imbibition) the genes encoding class 1 phytoglobin (the protein scavenging NO) and S-nitrosoglutathione reductase (scavenging S-nitrosoglutathione) were markedly expressed. More dormant cultivar exhibited lower ATP/ADP and ascorbate/dehydroascorbate ratios and lower lactate and alcohol dehydrogenase activities, while the production of NO and nitrosylation of proteins was higher as compared to the non-dormant cultivar. The obtained data indicate that at the onset of germination NO is actively generated causing nitrosylation of SH-groups and a switch from respiration to fermentation. After radicle protrusion the metabolism changes in a more reducing type as recorded by ratio of reduced and oxidized glutathione and ascorbate. The turnover of NO by the scavenging systems (phytoglobin, S-nitrosoglutathione reductase and interaction with ROS) might contribute to the maintenance of redox and energy balance of germinating seeds and lead to alleviation of dormancy. PMID:26909088

  11. BIOMONITORING OF REACTIVE OXYGEN SPECIES IN BIOLOGICAL FLUIDS

    EPA Science Inventory

    Elevated levels of reactive oxygen species (ROS) are associated with several disease processes in humans, including cancer, asthma, diabetes, and cardiac disease. We have explored whether ROS can be measured directly in human fluids, and their value as a biomarker of exposure an...

  12. Mitochondrial Reactive Oxygen Species Production in Excitable Cells: Modulators of Mitochondrial and Cell Function

    PubMed Central

    Camara, Amadou K. S.

    2009-01-01

    Abstract The mitochondrion is a major source of reactive oxygen species (ROS). Superoxide (O2•−) is generated under specific bioenergetic conditions at several sites within the electron-transport system; most is converted to H2O2 inside and outside the mitochondrial matrix by superoxide dismutases. H2O2 is a major chemical messenger that, in low amounts and with its products, physiologically modulates cell function. The redox state and ROS scavengers largely control the emission (generation scavenging) of O2•−. Cell ischemia, hypoxia, or toxins can result in excess O2•− production when the redox state is altered and the ROS scavenger systems are overwhelmed. Too much H2O2 can combine with Fe2+ complexes to form reactive ferryl species (e.g., Fe(IV) = O•). In the presence of nitric oxide (NO•), O2•− forms the reactant peroxynitrite (ONOO−), and ONOOH-induced nitrosylation of proteins, DNA, and lipids can modify their structure and function. An initial increase in ROS can cause an even greater increase in ROS and allow excess mitochondrial Ca2+ entry, both of which are factors that induce cell apoptosis and necrosis. Approaches to reduce excess O2•− emission include selectively boosting the antioxidant capacity, uncoupling of oxidative phosphorylation to reduce generation of O2•− by inducing proton leak, and reversibly inhibiting electron transport. Mitochondrial cation channels and exchangers function to maintain matrix homeostasis and likely play a role in modulating mitochondrial function, in part by regulating O2•− generation. Cell-signaling pathways induced physiologically by ROS include effects on thiol groups and disulfide linkages to modify posttranslationally protein structure to activate/inactivate specific kinase/phosphatase pathways. Hypoxia-inducible factors that stimulate a cascade of gene transcription may be mediated physiologically by ROS. Our knowledge of the role played by ROS and their scavenging systems in

  13. Factors contributing to the high light tolerance of leaves in vivo - involvement of photo-protective energy dissipation and singlet oxygen scavenging.

    PubMed

    Hideg, Eva; Majer, Petra

    2010-01-01

    Contributions of preventive and antioxidant (energy dissipating and singlet oxygen neutralizing) processes to tolerating high light stress (photoinhibition) were examined in green-house grown tobacco (Nicotiana tabacum) plants acclimated to high or low light conditions and also in sun and shade leaves collected from a natural grown linden tree (Tilia platyphyllos). Tobacco leaves survived a short (1 h) exposure to photoinhibition by activating non-regulated non-photochemical quenching [Y(NO)] rather than relying on photo-protective, regulated non-photochemical quenching [Y(NPQ)]. Low light acclimated leaves had lower singlet oxygen scavenging ability and activated Y(NO) to a larger extent than high light acclimated ones. Low light grown leaves also suffered singlet oxygen mediated photo-damage, while no singlet oxygen was detected in high light acclimated leaves during photoinhibition. Natural grown linden leaves, however, coped with prolonged daily exposures to high light mainly by activating regulated non-photochemical quenching Y(NPQ), although they also featured very efficient singlet oxygen neutralizing. Our results suggest that high light tolerance is achieved by preventing photoinhibition of photosystem II via efficient photo-protective energy dissipation rather than relying on quenching of stress-induced pro-oxidative agents.

  14. Copper elevated embryonic hemoglobin through reactive oxygen species during zebrafish erythrogenesis.

    PubMed

    Zhou, Xin-Ying; Zhang, Ting; Ren, Long; Wu, Jun-Jie; Wang, Weimin; Liu, Jing-Xia

    2016-06-01

    Copper, as an essential trace mineral, can cause diseases such as childhood leukemia at excess levels, but has been applied in anemia therapy for a long time. However, few reports have studied its role during hematopoiesis at the molecular level in an animal model. In this study, by microarray, qRT-PCR, whole-mount in situ hybridization and O-dianisidine staining detections, we revealed the increased expression of hemoglobin in copper-exposed embryos. Secondly, we found that copper-exposed embryos exhibited high levels of reactive oxygen species (ROS), and genes in oxygen binding and oxygen transporting were up-regulated in the embryos. Finally, we found that ROS scavengers NAC, GSH, and DMTU not only inhibited in vivo ROS levels induced by copper, but also significantly decreased high expression of hemoglobin back to almost normal levels in copper exposed embryos, and also helped with copper elimination from the embryos. Our data first demonstrated that ROS mediated copper induced hemoglobin expression in vertebrates, partly revealing the underlying molecular mechanism of copper therapy for anemia. Moreover, we revealed that copper homeostasis was broken by its induced ROS and ROS helped with copper overloading in the body, which could be applied as a novel therapy target for copper-caused diseases.

  15. CLOCK Promotes Endothelial Damage by Inducing Autophagy through Reactive Oxygen Species

    PubMed Central

    Tang, Xiao; Lin, Changpo; Guo, Daqiao; Qian, Ruizhe; Li, Xiaobo; Shi, Zhenyu; Liu, Jianjun; Li, Xu

    2016-01-01

    A number of recent studies have implicated that autophagy was activated by reactive oxygen species (ROS). Our previous report indicated that CLOCK increased the accumulation of ROS under hypoxic conditions. In this study, we investigated the mechanisms by which CLOCK mediated endothelial damage, focusing on the involvement of oxidative damage and autophagy. Overexpression of CLOCK in human umbilical vein endothelial cells (HUVECs) showed inhibition of cell proliferation and higher autophagosome with an increased expression of Beclin1 and LC3-I/II under hypoxic conditions. In contrast, CLOCK silencing reversed these effects. Interestingly, pretreatment with 3-methyladenine (3-MA) resulted in the attenuation of CLOCK-induced cell autophagy and but did not influence the production of intracellular reactive oxygen species (ROS). Furthermore, Tiron (4,5-dihydroxy-1,3-benzene disulfonic acid-disodium salt), a ROS scavenger, significantly attenuated CLOCK-induced cell autophagy. In addition, we found that overexpression of CLOCK had no significant effects on the production of ROS and expression of Beclin1 and LC3-I/II under normoxic conditions in HUVEC. In this present investigation, our results suggested a novel mechanism of action of CLOCK in HUVECs, opening up the possibility of targeting CLOCK for the treatment of vascular diseases. PMID:28058089

  16. Protective activity of propofol, Diprivan and intralipid against active oxygen species.

    PubMed Central

    Mathy-Hartert, M; Deby-Dupont, G; Hans, P; Deby, C; Lamy, M

    1998-01-01

    We separately studied the antioxidant properties of propofol (PPF), Diprivan (the commercial form of PPF) and intralipid (IL) (the vehicle solution of PPF in Diprivan) on active oxygen species produced by phorbol myristate acetate (10(-6) M)-stimulated human polymorphonuclear leukocytes (PMN: 5 x 10(5) cells/assay), human endothelial cells (5 x 10(5) cells/assay) or cell-free systems (NaOCl or H2O2/peroxidase systems), using luminol (10(-4) M)-enhanced chemiluminescence (CL). We also studied the protective effects of Diprivan on endothelial cells submitted to an oxidant stress induced by H2O2/MPO system: cytotoxicity was assessed by the release of preincorporated 51Cr. Propofol inhibited the CL produced by stimulated PMN in a dose dependent manner (until 5 x 10(-5) M, a clinically relevant concentration), while Diprivan and IL were not dose-dependent inhibitors. The CL produced by endothelial cells was dose-dependently inhibited by Diprivan and PPF, and weakly by IL (not dose-dependent). In cell free systems, dose-dependent inhibitions were obtained for the three products with a lower effect for IL. Diprivan efficaciously protected endothelial cells submitted to an oxidant stress, while IL was ineffective. By HPLC, we demonstrated that PPF was not incorporated into the cells. The drug thus acted by scavenging the active oxygen species released in the extracellular medium. IL acted in the same manner, but was a less powerful antioxidant. PMID:9883967

  17. Properties of reactive oxygen species by quantum Monte Carlo.

    PubMed

    Zen, Andrea; Trout, Bernhardt L; Guidoni, Leonardo

    2014-07-07

    The electronic properties of the oxygen molecule, in its singlet and triplet states, and of many small oxygen-containing radicals and anions have important roles in different fields of chemistry, biology, and atmospheric science. Nevertheless, the electronic structure of such species is a challenge for ab initio computational approaches because of the difficulties to correctly describe the statical and dynamical correlation effects in presence of one or more unpaired electrons. Only the highest-level quantum chemical approaches can yield reliable characterizations of their molecular properties, such as binding energies, equilibrium structures, molecular vibrations, charge distribution, and polarizabilities. In this work we use the variational Monte Carlo (VMC) and the lattice regularized Monte Carlo (LRDMC) methods to investigate the equilibrium geometries and molecular properties of oxygen and oxygen reactive species. Quantum Monte Carlo methods are used in combination with the Jastrow Antisymmetrized Geminal Power (JAGP) wave function ansatz, which has been recently shown to effectively describe the statical and dynamical correlation of different molecular systems. In particular, we have studied the oxygen molecule, the superoxide anion, the nitric oxide radical and anion, the hydroxyl and hydroperoxyl radicals and their corresponding anions, and the hydrotrioxyl radical. Overall, the methodology was able to correctly describe the geometrical and electronic properties of these systems, through compact but fully-optimised basis sets and with a computational cost which scales as N(3) - N(4), where N is the number of electrons. This work is therefore opening the way to the accurate study of the energetics and of the reactivity of large and complex oxygen species by first principles.

  18. Properties of reactive oxygen species by quantum Monte Carlo

    NASA Astrophysics Data System (ADS)

    Zen, Andrea; Trout, Bernhardt L.; Guidoni, Leonardo

    2014-07-01

    The electronic properties of the oxygen molecule, in its singlet and triplet states, and of many small oxygen-containing radicals and anions have important roles in different fields of chemistry, biology, and atmospheric science. Nevertheless, the electronic structure of such species is a challenge for ab initio computational approaches because of the difficulties to correctly describe the statical and dynamical correlation effects in presence of one or more unpaired electrons. Only the highest-level quantum chemical approaches can yield reliable characterizations of their molecular properties, such as binding energies, equilibrium structures, molecular vibrations, charge distribution, and polarizabilities. In this work we use the variational Monte Carlo (VMC) and the lattice regularized Monte Carlo (LRDMC) methods to investigate the equilibrium geometries and molecular properties of oxygen and oxygen reactive species. Quantum Monte Carlo methods are used in combination with the Jastrow Antisymmetrized Geminal Power (JAGP) wave function ansatz, which has been recently shown to effectively describe the statical and dynamical correlation of different molecular systems. In particular, we have studied the oxygen molecule, the superoxide anion, the nitric oxide radical and anion, the hydroxyl and hydroperoxyl radicals and their corresponding anions, and the hydrotrioxyl radical. Overall, the methodology was able to correctly describe the geometrical and electronic properties of these systems, through compact but fully-optimised basis sets and with a computational cost which scales as N3 - N4, where N is the number of electrons. This work is therefore opening the way to the accurate study of the energetics and of the reactivity of large and complex oxygen species by first principles.

  19. Properties of reactive oxygen species by quantum Monte Carlo

    SciTech Connect

    Zen, Andrea; Trout, Bernhardt L.; Guidoni, Leonardo

    2014-07-07

    The electronic properties of the oxygen molecule, in its singlet and triplet states, and of many small oxygen-containing radicals and anions have important roles in different fields of chemistry, biology, and atmospheric science. Nevertheless, the electronic structure of such species is a challenge for ab initio computational approaches because of the difficulties to correctly describe the statical and dynamical correlation effects in presence of one or more unpaired electrons. Only the highest-level quantum chemical approaches can yield reliable characterizations of their molecular properties, such as binding energies, equilibrium structures, molecular vibrations, charge distribution, and polarizabilities. In this work we use the variational Monte Carlo (VMC) and the lattice regularized Monte Carlo (LRDMC) methods to investigate the equilibrium geometries and molecular properties of oxygen and oxygen reactive species. Quantum Monte Carlo methods are used in combination with the Jastrow Antisymmetrized Geminal Power (JAGP) wave function ansatz, which has been recently shown to effectively describe the statical and dynamical correlation of different molecular systems. In particular, we have studied the oxygen molecule, the superoxide anion, the nitric oxide radical and anion, the hydroxyl and hydroperoxyl radicals and their corresponding anions, and the hydrotrioxyl radical. Overall, the methodology was able to correctly describe the geometrical and electronic properties of these systems, through compact but fully-optimised basis sets and with a computational cost which scales as N{sup 3} − N{sup 4}, where N is the number of electrons. This work is therefore opening the way to the accurate study of the energetics and of the reactivity of large and complex oxygen species by first principles.

  20. Multiple antioxidant proteins protect Chlorobaculum tepidum against oxygen and reactive oxygen species.

    PubMed

    Li, Hui; Jubelirer, Sara; Garcia Costas, Amaya M; Frigaard, Niels-Ulrik; Bryant, Donald A

    2009-11-01

    The genome of the green sulfur bacterium Chlorobaculum (Cba.) tepidum, a strictly anaerobic photolithoautotroph, is predicted to encode more than ten genes whose products are potentially involved in protection from reactive oxygen species and an oxidative stress response. The encoded proteins include cytochrome bd quinol oxidase, NADH oxidase, rubredoxin oxygen oxidoreductase, several thiol peroxidases, alkyl hydroperoxide reductase, superoxide dismutase, methionine sulfoxide reductase, and rubrerythrin. To test the physiological functions of some of these proteins, ten genes were insertionally inactivated. Wild-type Cba. tepidum cells were very sensitive to oxygen in the light but were remarkably resistant to oxygen in the dark. When wild-type and mutant cells were subjected to air for various times under dark or light condition, significant decreases in viability were detected in most of the mutants relative to wild type. Treatments with hydrogen peroxide (H(2)O(2)), tert-butyl hydroperoxide (t-BOOH) and methyl viologen resulted in more severe effects in most of the mutants than in the wild type. The results demonstrated that these putative antioxidant proteins combine to form an effective defense against oxygen and reactive oxygen species. Reverse-transcriptase polymerase chain reaction studies showed that the genes with functions in oxidative stress protection were constitutively transcribed under anoxic growth conditions.

  1. Hydrazide derivatives produce active oxygen species as hydrazine.

    PubMed

    Timperio, Anna Maria; Rinalducci, Sara; Zolla, Lello

    2005-12-01

    It is well documented that some hydrazines are quite sensitive to oxidation and may serve as the electron donor for the reduction of oxygen, whereas hydrazides are not believed to react directly with oxygen. Data presented in this paper show that both hydrazides and hydrazines share an N-N moiety, which is assumed to react with atmospheric oxygen and produce oxygen radicals, at various degrees of efficiency. Since spectrometric measurements of hydrazide just after solubilization showed that the molecular mass remains constant in the absence of oxygen, we can conclude that hydrazides do not react with the oxygen through a slow spontaneous hydrolytic release of hydrazine. However, hydrazine is more reactive than hydrazide, which requires hours rather than minutes to produce measurable quantities of radical species. Differences were also apparent for various substituted derivatives. The reaction was significantly enhanced by the presence of metal ions. Data reported here demonstrate that hydrazides cause irreversible damage to the prosthetic group of proteins as well as causing degradation of the polypeptide chain into small fragments.

  2. Reactive oxygen species generation and signaling in plants

    PubMed Central

    Tripathy, Baishnab Charan; Oelmüller, Ralf

    2012-01-01

    The introduction of molecular oxygen into the atmosphere was accompanied by the generation of reactive oxygen species (ROS) as side products of many biochemical reactions. ROS are permanently generated in plastids, peroxisomes, mitochiondria, the cytosol and the apoplast. Imbalance between ROS generation and safe detoxification generates oxidative stress and the accumulating ROS are harmful for the plants. On the other hand, specific ROS function as signaling molecules and activate signal transduction processes in response to various stresses. Here, we summarize the generation of ROS in the different cellular compartments and the signaling processes which are induced by ROS. PMID:23072988

  3. Oxygen delivery, consumption, and conversion to reactive oxygen species in experimental models of diabetic retinopathy

    PubMed Central

    Eshaq, Randa S.; Wright, William S.; Harris, Norman R.

    2014-01-01

    Retinal tissue receives its supply of oxygen from two sources – the retinal and choroidal circulations. Decreases in retinal blood flow occur in the early stages of diabetes, with the eventual development of hypoxia thought to contribute to pathological neovascularization. Oxygen consumption in the retina has been found to decrease in diabetes, possibly due to either a reduction in neuronal metabolism or to cell death. Diabetes also enhances the rate of conversion of oxygen to superoxide in the retina, with experimental evidence suggesting that mitochondrial superoxide not only drives the overall production of reactive oxygen species, but also initiates several pathways leading to retinopathy, including the increased activity of the polyol and hexosamine pathways, increased production of advanced glycation end products and expression of their receptors, and activation of protein kinase C. PMID:24936440

  4. The effect of a Ta oxygen scavenger layer on HfO2-based resistive switching behavior: Thermodynamic stability, electronic structure, and low-bias transport

    SciTech Connect

    Zhong, Xiaoliang; Rungger, Ivan; Zapol, Peter; Nakamura, Hisao; Asai, Yoshihiro; Heinonen, Olle

    2016-02-15

    Reversible resistive switching between high-resistance and low-resistance states in metal-oxide-metal heterostructures makes them very interesting for applications in random access memories. While recent experimental work has shown that inserting a metallic "oxygen scavenger layer'' between the positive electrode and oxide improves device performance, the fundamental understanding of how the scavenger layer modifies the heterostructure properties is lacking. We use density functional theory to calculate thermodynamic properties and conductance of TiN/HfO2/TiN heterostructures with and without a Ta scavenger layer. First, we show that Ta insertion lowers the formation energy of low-resistance states. Second, while the Ta scavenger layer reduces the Schottky barrier height in the high-resistance state by modifying the interface charge at the oxide-electrode interface, the heterostructure maintains a high resistance ratio between high-and low-resistance states. Lastly, we show that the low-bias conductance of device on-states becomes much less sensitive to the spatial distribution of oxygen removed from the HfO2 in the presence of the Ta layer. By providing a fundamental understanding of the observed improvements with scavenger layers, we open a path to engineer interfaces with oxygen scavenger layers to control and enhance device performance. In turn, this may enable the realization of a non-volatile low-power memory technology with concomitant reduction in energy consumption by consumer electronics and offering significant benefits to society.

  5. ARSENIC SPECIES CAUSE RELEASE OF IRON FROM FERRITIN GENERATING REACTIVE OXYGEN SPECIES

    EPA Science Inventory

    ARSENIC SPECIES CAUSE RELEASE OF IRON FROM FERRITIN GENERATING REACTIVE OXYGEN SPECIES

    Arsenic-associated cancer (lung, bladder, skin, liver, kidney) remains a significant world- wide public health problem (e.g., Taiwan, Chile, Bangladesh, India, China and Thailand). Rece...

  6. ARSENIC SPECIES CAUSE RELEASE OF IRON FROM FERRITIN GENERATING REACTIVIE OXYGEN SPECIES

    EPA Science Inventory

    ARSENIC SPECIES. CAUSE RELEASE OF IRON , FROM FERRITIN GENERATING REACTIVE OXYGEN SPECIES

    Arsenic-associated cancer (lung, bladder, skin, liver, kidney) remains a significant world- wide public health problem (e.g., Taiwan, Chile, Bangladesh, India, China and Thailand). R...

  7. The scavenger receptor repertoire in six cnidarian species and its putative role in cnidarian-dinoflagellate symbiosis

    PubMed Central

    Neubauer, Emilie F.; Poole, Angela Z.; Davy, Simon K.

    2016-01-01

    Many cnidarians engage in a mutualism with endosymbiotic photosynthetic dinoflagellates that forms the basis of the coral reef ecosystem. Interpartner interaction and regulation includes involvement of the host innate immune system. Basal metazoans, including cnidarians have diverse and complex innate immune repertoires that are just beginning to be described. Scavenger receptors (SR) are a diverse superfamily of innate immunity genes that recognize a broad array of microbial ligands and participate in phagocytosis of invading microbes. The superfamily includes subclades named SR-A through SR-I that are categorized based on the arrangement of sequence domains including the scavenger receptor cysteine rich (SRCR), the C-type lectin (CTLD) and the CD36 domains. Previous functional and gene expression studies on cnidarian-dinoflagellate symbiosis have implicated SR-like proteins in interpartner communication and regulation. In this study, we characterized the SR repertoire from a combination of genomic and transcriptomic resources from six cnidarian species in the Class Anthozoa. We combined these bioinformatic analyses with functional experiments using the SR inhibitor fucoidan to explore a role for SRs in cnidarian symbiosis and immunity. Bioinformatic searches revealed a large diversity of SR-like genes that resembled SR-As, SR-Bs, SR-Es and SR-Is. SRCRs, CTLDs and CD36 domains were identified in multiple sequences in combinations that were highly homologous to vertebrate SRs as well as in proteins with novel domain combinations. Phylogenetic analyses of CD36 domains of the SR-B-like sequences from a diversity of metazoans grouped cnidarian with bilaterian sequences separate from other basal metazoans. All cnidarian sequences grouped together with moderate support in a subclade separately from bilaterian sequences. Functional experiments were carried out on the sea anemone Aiptasia pallida that engages in a symbiosis with Symbiodinium minutum (clade B1

  8. HIV-1, Reactive Oxygen Species and Vascular Complications

    PubMed Central

    Porter, Kristi M.; Sutliff, Roy L.

    2012-01-01

    Over 1 million people in the United States and 33 million individuals worldwide suffer from HIV/AIDS. Since its discovery, HIV/AIDS has been associated with an increased susceptibility to opportunistic infection due to immune dysfunction. Highly active antiretroviral therapies (HAART) restore immune function and, as a result, people infected with HIV-1 are living longer. This improved survival of HIV-1 patients has revealed a previously unrecognized risk of developing vascular complications, such as atherosclerosis and pulmonary hypertension. The mechanisms underlying these HIV-associated vascular disorders are poorly understood. However, HIV-induced elevations in reactive oxygen species, including superoxide and hydrogen peroxide, may contribute to vascular disease development and progression by altering cell function and redox-sensitive signaling pathways. In this review, we summarize the clinical and experimental evidence demonstrating HIV- and HIV antiretroviral therapy-induced alterations in reactive oxygen species (ROS) and how these effects likely contribute to vascular dysfunction and disease. PMID:22564529

  9. The influence of reactive oxygen species on local redox conditions in oxygenated natural waters

    NASA Astrophysics Data System (ADS)

    Rose, Andrew

    2016-11-01

    Redox conditions in natural waters are a fundamental control on biogeochemical processes and ultimately many ecosystem functions. While the dioxygen/water redox couple controls redox thermodynamics in oxygenated aquatic environments on geological timescales, it is kinetically inert in the extracellular environment on the much shorter timescales on which many biogeochemical processes occur. Instead, electron transfer processes on these timescales are primarily mediated by a relatively small group of trace metals and stable radicals, including the reactive oxygen species superoxide. Such processes are of critical biogeochemical importance because many of these chemical species are scarce nutrients, but may also be toxic at high concentrations. Furthermore, their bioavailability and potentially toxicity is typically strongly influenced by their redox state. In this paper, I examine to what extent redox conditions in oxygenated natural waters are expected to be reflected in the redox states of labile redox-active compounds that readily exchange electrons with the dioxygen/superoxide redox couple, and potentially with each other. Additionally, I present the hypothesis that that the relative importance of the dioxygen/superoxide and superoxide/hydrogen peroxide redox couples exerts a governing control on local redox conditions in oxygenated natural waters on biogeochemically important timescales. Given the recent discovery of widespread extracellular superoxide production by a diverse range of organisms, this suggests the existence of a fundamental mechanism for organisms to tightly regulate local redox conditions in their extracellular environment in oxygenated natural waters.

  10. Quantification of reactive oxygen species for photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Tan, Zou; Zhang, Jinde; Lin, Lisheng; Li, Buhong

    2016-10-01

    Photodynamic therapy (PDT) is an effective therapeutic modality that uses a light source to activate light-sensitive photosensitizers to treat both oncologic and nononcological indications. Photosensitizers are excited to the long-lived triplet state, and they react with biomolecules via type I or II mechanism resulted in cell death and tumor necrosis. Free radicals and radical ions are formed by electron transfer reactions (type I), which rapidly react with oxygen leading to the production of reactive oxygen species (ROS), including superoxide ions, hydroxyl radicals and hydrogen peroxide. Singlet molecular oxygen is produced in a Type II reaction, in which the excited singlet state of the photosensitizer generated upon photon absorption by the ground-state photosensitizer molecule undergoes intersystem crossing to a long-lived triplet state. In this talk, the fundmental mechanisms and detection techniques for ROS generation in PDT will be introduced. In particular, the quantification of singlet oxygen generation for pre-clinical application will be highlighted, which plays an essential role in the establishment of robust singlet oxygen-mediated PDT dosimetry.

  11. Multi-species simulation of Trichel pulses in oxygen

    NASA Astrophysics Data System (ADS)

    Durán-Olivencia, F. J.; Pontiga, F.; Castellanos, A.

    2014-10-01

    The development of negative corona Trichel pulses in oxygen between a spherical cathode and a plane is investigated using a plasma chemical model of ten selected species, which includes electrons, ions and neutrals. The interaction among these species is described by a model that incorporates the most important plasma chemical processes, such as ionization, electron attachment and detachment, electron impact dissociation and excitation, and clustering. The spatio-temporal evolution of charged and neutral species and their reaction rates are evaluated along different moments during the pulses. The case of the first Trichel pulse is considered separately, since its characteristics clearly differ from the subsequent pulses. The results show that the negative space charge is constituted of different types of ions, depending on the stage of the pulse. Moreover, a spatial segregation of negative ions is observed during the post-pulse period. Regarding neutral species, ozone increases linearly with time, without being considerably affected by the occurrence of pulses.

  12. Mitochondria and Reactive Oxygen Species: Physiology and Pathophysiology

    PubMed Central

    Bolisetty, Subhashini; Jaimes, Edgar A.

    2013-01-01

    The air that we breathe contains nearly 21% oxygen, most of which is utilized by mitochondria during respiration. While we cannot live without it, it was perceived as a bane to aerobic organisms due to the generation of reactive oxygen and nitrogen metabolites by mitochondria and other cellular compartments. However, this dogma was challenged when these species were demonstrated to modulate cellular responses through altering signaling pathways. In fact, since this discovery of a dichotomous role of reactive species in immune function and signal transduction, research in this field grew at an exponential pace and the pursuit for mechanisms involved began. Due to a significant number of review articles present on the reactive species mediated cell death, we have focused on emerging novel pathways such as autophagy, signaling and maintenance of the mitochondrial network. Despite its role in several processes, increased reactive species generation has been associated with the origin and pathogenesis of a plethora of diseases. While it is tempting to speculate that anti-oxidant therapy would protect against these disorders, growing evidence suggests that this may not be true. This further supports our belief that these reactive species play a fundamental role in maintenance of cellular and tissue homeostasis. PMID:23528859

  13. Effect of electron scavengers on the formation of paramagnetic species upon radiolysis of polystyrene and its low-molecular-weight analogs

    SciTech Connect

    Zezin, A.A.; Fel`dman, V.I.; Sukhov, F.F.

    1995-05-01

    The effect of electron scavengers on the composition and the yields of paramagnetic species upon the radiolysis of polystyrene was examined. Various mechanisms of the reactions of radical cations (holes) in low-molecular-weight aromatic hydrocarbons and polystyrene are discussed. The dimeric radical cations were found to be trapped in polystyrene and benzene irradiated in the presence of electron scavengers at 77 K. The yield of paramagnetic species was shown to increase markedly in the presence of small amounts (<1%) of chloroform of benzyl chloride. The results obtained show that the ionic processes make a large contribution to the formation of paramagnetic species. It is concluded that the radiation resistance of polystyrene is due not only to its chemical structure, but to the association of phenyl rings in the solid polymer.

  14. Do leaf total antioxidant capacities (TAC) reflect specific antioxidant potentials? - A comparison of TAC and reactive oxygen scavenging in tobacco leaf extracts.

    PubMed

    Majer, Petra; Stoyanova, Silviya; Hideg, Eva

    2010-07-02

    Two traditional methods of total antioxidant capacity (TAC) assessment, Trolox equivalent antioxidant capacity (TEAC) and ferric reducing antioxidant power (FRAP) were applied to water extracts from tobacco leaves at various stages of senescence. Physiological status of the leaves was characterized by the effective photochemical quantum yield of photosynthesis (Y(II)). TAC values were compared to amounts of total phenolics, carotenoid contents and also to reactive oxygen scavenging capacities of the leaf extracts. To this end a new, simple fluorimetric assay was introduced for testing hydroxyl radical neutralizing capacity in leaf extracts. We found that while both TAC values increased with declining photosynthesis and decreasing pigment content, they were not characteristic to specific superoxide or hydroxyl radical scavenging and had limited connection to leaf antioxidant content. Good linear correlations were only found between the following pairs of parameters: Y(II) - total carotenoid, TEAC - total carotenoid, FRAP - total phenolics. Our data show that TEAC and FRAP are not interchangeable in leaf studies and do not represent antioxidant action on ROS.

  15. Mitochondrial-derived reactive oxygen species (ROS) play a causal role in aging-related intervertebral disc degeneration.

    PubMed

    Nasto, Luigi A; Robinson, Andria R; Ngo, Kevin; Clauson, Cheryl L; Dong, Qing; St Croix, Claudette; Sowa, Gwendolyn; Pola, Enrico; Robbins, Paul D; Kang, James; Niedernhofer, Laura J; Wipf, Peter; Vo, Nam V

    2013-07-01

    Oxidative damage is a well-established driver of aging. Evidence of oxidative stress exists in aged and degenerated discs, but it is unclear how it affects disc metabolism. In this study, we first determined whether oxidative stress negatively impacts disc matrix metabolism using disc organotypic and cell cultures. Mouse disc organotypic culture grown at atmospheric oxygen (20% O(2)) exhibited perturbed disc matrix homeostasis, including reduced proteoglycan synthesis and enhanced expression of matrix metalloproteinases, compared to discs grown at low oxygen levels (5% O(2)). Human disc cells grown at 20% O(2) showed increased levels of mitochondrial-derived superoxide anions and perturbed matrix homeostasis. Treatment of disc cells with the mitochondria-targeted reactive oxygen species (ROS) scavenger XJB-5-131 blunted the adverse effects caused by 20% O(2). Importantly, we demonstrated that treatment of accelerated aging Ercc1(-/Δ) mice, previously established to be a useful in vivo model to study age-related intervertebral disc degeneration (IDD), also resulted in improved disc total glycosaminoglycan content and proteoglycan synthesis. This demonstrates that mitochondrial-derived ROS contributes to age-associated IDD in Ercc1(-/Δ) mice. Collectively, these data provide strong experimental evidence that mitochondrial-derived ROS play a causal role in driving changes linked to aging-related IDD and a potentially important role for radical scavengers in preventing IDD.

  16. Inhibitory effects of fluvastain and its metabolites on the formation of several reactive oxygen species.

    PubMed

    Nakashima, A; Ohtawa, M; Iwasaki, K; Wada, M; Kuroda, N; Nakashima, K

    2001-08-10

    We investigated the inhibitory effects of fluvastain (FV) and its metabolites (M-2, M-3, M-4, M-5, and M-7) on the formation of several reactive oxygen species (ROS), such as singlet oxygen (1O2), superoxide anion (O2-), hydroxy radical (*OH), hypochlorite ion (OCL-), and linoleic acid peroxide (LOO*). Inhibitory effects of pravastatin (PV), simvastatin (SV), probucol (PR) and alpha-tocopherol (TOC) were also tested. The inhibitory effects of 5-hydroxy FV (M-2) and 6-hydroxy FV (M-3) on the formation of 1O2, O2-, *OH, and OCL- were strongest. Scavenging of 1O2 by M-4, M-5, (+)-FV, and (-)-FV was also noted. The inhibitory effects of (+)-FV on the formation of 1O2 were comparable to those of (-)-FV, PV, SV, PR and M-7 had little or no inhibitory effect on the formation of several ROS. In conclusion, FV and its metabolites, particulary M-2 and M-3, have the potential to protect against oxidative stress mediated by several ROS.

  17. Applying Knowledge of Species-Typical Scavenging Behavior to the Search and Recovery of Mammalian Skeletal Remains.

    PubMed

    Young, Alexandria; Stillman, Richard; Smith, Martin J; Korstjens, Amanda H

    2016-03-01

    Forensic investigations involving animal scavenging of human remains require a physical search of the scene and surrounding areas. However, there is currently no standard procedure in the U.K. for physical searches of scavenged human remains. The Winthrop and grid search methods used by police specialist searchers for scavenged remains were examined through the use of mock red fox (Vulpes vulpes) scatter scenes. Forty-two police specialist searchers from two different regions within the U.K. were divided between those briefed and not briefed with fox-typical scavenging information. Briefing searchers with scavenging information significantly affected the recovery of scattered bones (χ(2) = 11.45, df = 1, p = 0.001). Searchers briefed with scavenging information were 2.05 times more likely to recover bones. Adaptions to search methods used by searchers were evident on a regional level, such that searchers more accustom to a peri-urban to rural region recovered a higher percentage of scattered bones (58.33%, n = 84).

  18. Cytotoxic responses to 405nm light exposure in mammalian and bacterial cells: Involvement of reactive oxygen species.

    PubMed

    Ramakrishnan, Praveen; Maclean, Michelle; MacGregor, Scott J; Anderson, John G; Grant, M Helen

    2016-06-01

    Light at wavelength 405 nm is an effective bactericide. Previous studies showed that exposing mammalian cells to 405 nm light at 36 J/cm(2) (a bactericidal dose) had no significant effect on normal cell function, although at higher doses (54 J/cm(2)), mammalian cell death became evident. This research demonstrates that mammalian and bacterial cell toxicity induced by 405 nm light exposure is accompanied by reactive oxygen species production, as detected by generation of fluorescence from 6-carboxy-2',7'-dichlorodihydrofluorescein diacetate. As indicators of the resulting oxidative stress in mammalian cells, a decrease in intracellular reduced glutathione content and a corresponding increase in the efflux of oxidised glutathione were observed from 405 nm light treated cells. The mammalian cells were significantly protected from dying at 54 J/cm(2) in the presence of catalase, which detoxifies H2O2. Bacterial cells were significantly protected by sodium pyruvate (H2O2 scavenger) and by a combination of free radical scavengers (sodium pyruvate, dimethyl thiourea (OH scavenger) and catalase) at 162 and 324 J/cm(2). Results therefore suggested that the cytotoxic mechanism of 405 nm light in mammalian cells and bacteria could be oxidative stress involving predominantly H2O2 generation, with other ROS contributing to the damage.

  19. Reactive oxygen species produced from chromate pigments and ascorbate.

    PubMed Central

    Lefebvre, Y; Pezerat, H

    1994-01-01

    The reactions of various chromate pigments and ascorbate were investigated by an ESR spin trapping technique. Production of Cr(V) was detected directly and productions of very electrophilic reactive oxygen species (ROS) was detected via the oxidation of formate. We demonstrated previously that both dissolved oxygen and Cr (V) were essential in the production of ROS in this system, and that ROS production was inhibited by catalase. We studied here the effect of solubility of different chromate pigments: sodium, calcium, strontium, basic zinc, basic lead supported on silica, and lead and barium chromates on the production of ROS in buffered medium and cell culture medium (Dublecco's Modified Eagle medium + fetal calf serum). Sodium, calcium, basic zinc, and basic lead chromates were active in the production of ROS in presence of cell culture medium, whereas lead and barium chromates were inactive. PMID:7843106

  20. Mn (III) tetrakis (4-benzoic acid) porphyrin scavenges reactive species, reduces oxidative stress, and improves functional recovery after experimental spinal cord injury in rats: comparison with methylprednisolone

    PubMed Central

    2013-01-01

    Background Substantial experimental evidence supports that reactive species mediate secondary damage after traumatic spinal cord injury (SCI) by inducing oxidative stress. Removal of reactive species may reduce secondary damage following SCI. This study explored the effectiveness of a catalytic antioxidant - Mn (III) tetrakis (4-benzoic acid) porphyrin (MnTBAP) - in removing reactive oxygen species (ROS), reducing oxidative stress, and improving functional recovery in vivo in a rat impact SCI model. The efficiency of MnTBAP was also compared with that of methylprednisolone – the only drug used clinically in treating acute SCI. Results In vivo measurements of time courses of ROS production by microdialysis and microcannula sampling in MnTBAP, methylprednisolone, and saline (as vehicle control)-treated SCI rats showed that both agents significantly reduced the production of hydrogen peroxide, but only MnTBAP significantly reduced superoxide elevation after SCI. In vitro experiments further demonstrated that MnTBAP scavenged both of the preceding ROS, whereas methylprednisolone had no effect on either. By counting the immuno-positive neurons in the spinal cord sections immunohistochemically stained with anti-nitrotyrosine and anti-4-hydroxy-nonenal antibodies as the markers of protein nitration and membrane lipid peroxidation, we demonstrated that MnTBAP significantly reduced the numbers of 4-hydroxy-nonenal-positive and nitrotyrosine-positive neurons in the sections at 1.55 to 2.55 mm and 1.1 to 3.1 mm, respectively, rostral to the injury epicenter compared to the vehicle-treated animals. By behavioral tests (open field and inclined plane tests), we demonstrated that at 4 hours post-SCI treatment with MnTBAP and the standard methylprednisolone regimen both significantly increased test scores compared to those produced by vehicle treatment. However, the outcomes for MnTBAP-treated rats were significantly better than those for methylprednisolone-treated animals

  1. Antimalarial action of artesunate involves DNA damage mediated by reactive oxygen species.

    PubMed

    Gopalakrishnan, Anusha M; Kumar, Nirbhay

    2015-01-01

    Artemisinin-based combination therapy (ACT) is the recommended first-line treatment for Plasmodium falciparum malaria. It has been suggested that the cytotoxic effect of artemisinin is mediated by free radicals followed by the alkylation of P. falciparum proteins. The endoperoxide bridge, the active moiety of artemisinin derivatives, is cleaved in the presence of ferrous iron, generating reactive oxygen species (ROS) and other free radicals. However, the emergence of resistance to artemisinin in P. falciparum underscores the need for new insights into the molecular mechanisms of antimalarial activity of artemisinin. Here we show that artesunate (ART) induces DNA double-strand breaks in P. falciparum in a physiologically relevant dose- and time-dependent manner. DNA damage induced by ART was accompanied by an increase in the intracellular ROS level in the parasites. Mannitol, a ROS scavenger, reversed the cytotoxic effect of ART and reduced DNA damage, and modulation of glutathione (GSH) levels was found to impact ROS and DNA damage induced by ART. Accumulation of ROS, increased DNA damage, and the resulting antiparasite effect suggest a causal relationship between ROS, DNA damage, and parasite death. Finally, we also show that ART-induced ROS production involves a potential role for NADPH oxidase, an enzyme involved in the production of superoxide anions. Our results with P. falciparum provide novel insights into previously unknown molecular mechanisms underlying the antimalarial activity of artemisinin derivatives and may help in the design of next-generation antimalarial drugs against the most virulent Plasmodium species.

  2. Rapid Hydrogen and Oxygen Atom Transfer by a High-Valent Nickel-Oxygen Species.

    PubMed

    Corona, Teresa; Draksharapu, Apparao; Padamati, Sandeep K; Gamba, Ilaria; Martin-Diaconescu, Vlad; Acuña-Parés, Ferran; Browne, Wesley R; Company, Anna

    2016-10-05

    Terminal high-valent metal-oxygen species are key reaction intermediates in the catalytic cycle of both enzymes (e.g., oxygenases) and synthetic oxidation catalysts. While tremendous efforts have been directed toward the characterization of the biologically relevant terminal manganese-oxygen and iron-oxygen species, the corresponding analogues based on late-transition metals such as cobalt, nickel or copper are relatively scarce. This scarcity is in part related to the "Oxo Wall" concept, which predicts that late transition metals cannot support a terminal oxido ligand in a tetragonal environment. Here, the nickel(II) complex (1) of the tetradentate macrocyclic ligand bearing a 2,6-pyridinedicarboxamidate unit is shown to be an effective catalyst in the chlorination and oxidation of C-H bonds with sodium hypochlorite as terminal oxidant in the presence of acetic acid (AcOH). Insight into the active species responsible for the observed reactivity was gained through the study of the reaction of 1 with ClO(-) at low temperature by UV-vis absorption, resonance Raman, EPR, ESI-MS, and XAS analyses. DFT calculations aided the assignment of the trapped chromophoric species (3) as a nickel-hypochlorite species. Despite the fact that the formal oxidation state of the nickel in 3 is +4, experimental and computational analysis indicate that 3 is best formulated as a Ni(III) complex with one unpaired electron delocalized in the ligands surrounding the metal center. Most remarkably, 3 reacts rapidly with a range of substrates including those with strong aliphatic C-H bonds, indicating the direct involvement of 3 in the oxidation/chlorination reactions observed in the 1/ClO(-)/AcOH catalytic system.

  3. Activation mechanism of Gi and Go by reactive oxygen species.

    PubMed

    Nishida, Motohiro; Schey, Kevin L; Takagahara, Shuichi; Kontani, Kenji; Katada, Toshiaki; Urano, Yasuteru; Nagano, Tetsuo; Nagao, Taku; Kurose, Hitoshi

    2002-03-15

    Reactive oxygen species are proposed to work as intracellular mediators. One of their target proteins is the alpha subunit of heterotrimeric GTP-binding proteins (Galpha(i) and Galpha(o)), leading to activation. H(2)O(2) is one of the reactive oxygen species and activates purified Galpha(i2). However, the activation requires the presence of Fe(2+), suggesting that H(2)O(2) is converted to more reactive species such as c*OH. The analysis with mass spectrometry shows that seven cysteine residues (Cys(66), Cys(112), Cys(140), Cys(255), Cys(287), Cys(326), and Cys(352)) of Galpha(i2) are modified by the treatment with *OH. Among these cysteine residues, Cys(66), Cys(112), Cys(140), Cys(255), and Cys(352) are not involved in *OH-induced activation of Galpha(i2). Although the modification of Cys(287) but not Cys(326) is required for subunit dissociation, the modification of both Cys(287) and Cys(326) is necessary for the activation of Galpha(i2) as determined by pertussis toxin-catalyzed ADP-ribosylation, conformation-dependent change of trypsin digestion pattern or guanosine 5'-3-O-(thio)triphosphate binding. Wild type Galpha(i2) but not Cys(287)- or Cys(326)-substituted mutants are activated by UV light, singlet oxygen, superoxide anion, and nitric oxide, indicating that these oxidative stresses activate Galpha(i2) by the mechanism similar to *OH-induced activation. Because Cys(287) exists only in G(i) family, this study explains the selective activation of G(i)/G(o) by oxidative stresses.

  4. Reactive oxygen species in regulation of fungal development.

    PubMed

    Gessler, N N; Aver'yanov, A A; Belozerskaya, T A

    2007-10-01

    Reactive oxygen species (ROS) are formed by fungi in the course of metabolic activity. ROS production increases in fungi due to various stress agents such as starvation, light, mechanical damage, and interactions with some other living organisms. Regulation of ROS level appears to be very important during development of the fungal organism. ROS sources in fungal cells, their sensors, and ROS signal transduction pathways are discussed in this review. Antioxidant defense systems in different classes of fungi are characterized in detail. Particular emphasis is placed on ROS functions in interactions of phytopathogenic fungi with plant cells.

  5. Manganese Neurotoxicity and the Role of Reactive Oxygen Species

    PubMed Central

    Martinez-Finley, Ebany J.; Gavin, Claire E; Aschner, Michael; Gunter, Thomas E.

    2013-01-01

    Manganese (Mn) is an essential dietary nutrient but excess or accumulations can be toxic. Disease states, like manganism, are associated with overexposure or accumulation of Mn and are due to the production of reactive oxygen species, free radicals and toxic metabolites, alteration of mitochondrial function and ATP production and depletion of cellular antioxidant defense mechanisms. This review focuses on all of the preceding mechanisms and the scientific studies that support them as well as provides an overview of the absorption, distribution, and excretion of Mn and the stability and transport of Mn compounds in the body. PMID:23395780

  6. Nitric oxide and reactive oxygen species in plant biotic interactions.

    PubMed

    Scheler, Claudia; Durner, Jörg; Astier, Jeremy

    2013-08-01

    Nitric oxide (NO) and reactive oxygen species (ROS) are important signaling molecules in plants. Recent progress has been made in defining their role during plant biotic interactions. Over the last decade, their function in disease resistance has been highlighted and focused a lot of investigations. Moreover, NO and ROS have recently emerged as important players of defense responses after herbivore attacks. Besides their role in plant adaptive response development, NO and ROS have been demonstrated to be involved in symbiotic interactions between plants and microorganisms. Here we review recent data concerning these three sides of NO and ROS functions in plant biotic interactions.

  7. Effects of oxygen on fracturing fluids

    SciTech Connect

    Walker, M.L.; Shuchart, C.E.; Yaritz, J.G.; Norman, L.R.

    1995-11-01

    The stability of polysaccharide gels at high temperature is limited by such factors as pH, mechanical degradation, and oxidants. Oxygen is unavoidably placed in fracturing fluids through dissolution of air. To prevent premature degradation of the fracturing fluid by this oxidant, oxygen scavengers are commonly used. In this paper, the effects of oxygen and various oxygen scavengers on gel stability will be presented. Mechanical removal of oxygen resulted in surprisingly stable fracturing gels at 275 F. However, chemical removal of oxygen gave mixed results. Test data from sodium thiosulfate, sodium sulfite, and sodium erythorbate used as oxygen scavengers/gel stabilizers showed that the efficiency of oxygen removal from gels did not directly coincide with the viscosity retention of the gel, and large excesses of additives were necessary to provide optimum gel stabilization. The inability of some oxygen scavengers to stabilize the gel was the result of products created from the interaction of oxygen with the oxygen scavenger, which in turn, produced species that degraded the gel. The ideal oxygen scavenger should provide superior gel stabilization without creating detrimental side reaction products. Of the materials tested, sodium thiosulfate appeared to be the most beneficial.

  8. Nanotechnology for Electroanalytical Biosensors of Reactive Oxygen and Nitrogen Species.

    PubMed

    Seenivasan, Rajesh; Kolodziej, Charles; Karunakaran, Chandran; Burda, Clemens

    2017-04-10

    Over the past several decades, nanotechnology has contributed to the progress of biomedicine, biomarker discovery, and the development of highly sensitive electroanalytical / electrochemical biosensors for in vitro and in vivo monitoring, and quantification of oxidative and nitrosative stress markers like reactive oxygen species (ROS) and reactive nitrogen species (RNS). A major source of ROS and RNS is oxidative stress in cells, which can cause many human diseases, including cancer. Therefore, the detection of local concentrations of ROS (e. g. superoxide anion radical; O2(•-) ) and RNS (e. g. nitric oxide radical; NO(•) and its metabolites) released from biological systems is increasingly important and needs a sophisticated detection strategy to monitor ROS and RNS in vitro and in vivo. In this review, we discuss the nanomaterials-based ROS and RNS biosensors utilizing electrochemical techniques with emphasis on their biomedical applications.

  9. Mechanisms of group A Streptococcus resistance to reactive oxygen species

    PubMed Central

    Henningham, Anna; Döhrmann, Simon; Nizet, Victor; Cole, Jason N.

    2015-01-01

    Streptococcus pyogenes, also known as group A Streptococcus (GAS), is an exclusively human Gram-positive bacterial pathogen ranked among the ‘top 10’ causes of infection-related deaths worldwide. GAS commonly causes benign and self-limiting epithelial infections (pharyngitis and impetigo), and less frequent severe invasive diseases (bacteremia, toxic shock syndrome and necrotizing fasciitis). Annually, GAS causes 700 million infections, including 1.8 million invasive infections with a mortality rate of 25%. In order to establish an infection, GAS must counteract the oxidative stress conditions generated by the release of reactive oxygen species (ROS) at the infection site by host immune cells such as neutrophils and monocytes. ROS are the highly reactive and toxic byproducts of oxygen metabolism, including hydrogen peroxide (H2O2), superoxide anion (O2•−), hydroxyl radicals (OH•) and singlet oxygen (O2*), which can damage bacterial nucleic acids, proteins and cell membranes. This review summarizes the enzymatic and regulatory mechanisms utilized by GAS to thwart ROS and survive under conditions of oxidative stress. PMID:25670736

  10. Mechanisms of group A Streptococcus resistance to reactive oxygen species.

    PubMed

    Henningham, Anna; Döhrmann, Simon; Nizet, Victor; Cole, Jason N

    2015-07-01

    Streptococcus pyogenes, also known as group A Streptococcus (GAS), is an exclusively human Gram-positive bacterial pathogen ranked among the 'top 10' causes of infection-related deaths worldwide. GAS commonly causes benign and self-limiting epithelial infections (pharyngitis and impetigo), and less frequent severe invasive diseases (bacteremia, toxic shock syndrome and necrotizing fasciitis). Annually, GAS causes 700 million infections, including 1.8 million invasive infections with a mortality rate of 25%. In order to establish an infection, GAS must counteract the oxidative stress conditions generated by the release of reactive oxygen species (ROS) at the infection site by host immune cells such as neutrophils and monocytes. ROS are the highly reactive and toxic byproducts of oxygen metabolism, including hydrogen peroxide (H2O2), superoxide anion (O2•(-)), hydroxyl radicals (OH•) and singlet oxygen (O2*), which can damage bacterial nucleic acids, proteins and cell membranes. This review summarizes the enzymatic and regulatory mechanisms utilized by GAS to thwart ROS and survive under conditions of oxidative stress.

  11. In situ reactive oxygen species production for tertiary wastewater treatment.

    PubMed

    Guitaya, Léa; Drogui, Patrick; Blais, Jean François

    2015-05-01

    The goal of this research was to develop a new approach for tertiary water treatment, particularly disinfection and removal of refractory organic compounds, without adding any chemical. Hydrogen peroxide can indeed be produced from dissolved oxygen owing to electrochemical processes. Using various current intensities (1.0 to 4.0 A), it was possible to in situ produce relatively high concentration of H2O2 with a specific production rate of 0.05 × 10(-5) M/min/A. Likewise, by using ultraviolet-visible absorption spectroscopy method, it was shown that other reactive oxygen species (ROS) including HO(*) radical and O3 could be simultaneously formed during electrolysis. The ROS concentration passed from 0.45 × 10(-5) M after 20 min of electrolysis to a concentration of 2.87 × 10(-5) M after 100 min of electrolysis. The disinfection and the organic matter removal were relatively high during the tertiary treatment of municipal and domestic wastewaters. More than 90 % of organic compounds (chemical oxygen demand) can be removed, whereas 99 % of faecal coliform abatement can be reached. Likewise, the process was also effective in removing turbidity (more than 90 % of turbidity was removed) so that the effluent became more and more transparent.

  12. Do low oxygen environments facilitate marine invasions? Relative tolerance of native and invasive species to low oxygen conditions.

    PubMed

    Lagos, Marcelo E; Barneche, Diego R; White, Craig R; Marshall, Dustin J

    2017-02-17

    Biological invasions are one of the biggest threats to global biodiversity. Marine artificial structures are proliferating worldwide and provide a haven for marine invasive species. Such structures disrupt local hydrodynamics, which can lead to the formation of oxygen-depleted microsites. The extent to which native fauna can cope with such low oxygen conditions, and whether invasive species, long associated with artificial structures in flow-restricted habitats, have adapted to these conditions remains unclear. We measured water flow and oxygen availability in marinas and piers at the scales relevant to sessile marine invertebrates (mm). We then measured the capacity of invasive and native marine invertebrates to maintain metabolic rates under decreasing levels of oxygen using standard laboratory assays. We found that marinas reduce water flow relative to piers, and that local oxygen levels can be zero in low flow conditions. We also found that for species with erect growth forms, invasive species can tolerate much lower levels of oxygen relative to native species. Integrating the field and laboratory data showed that up to 30% of available microhabitats within low flow environments are physiologically stressful for native species, while only 18% of the same habitat is physiologically stressful for invasive species. These results suggest that invasive species have adapted to low oxygen habitats associated with manmade habitats, and artificial structures may be creating niche opportunities for invasive species.

  13. Generation of reactive oxygen species by raphidophycean phytoplankton.

    PubMed

    Oda, T; Nakamura, A; Shikayama, M; Kawano, I; Ishimatsu, A; Muramatsu, T

    1997-10-01

    Chattonella marina, a raphidophycean flagellate, is one of the most toxic red tide phytoplankton and causes severe damage to fish farming. Recent studies demonstrated that Chattonella sp. generates superoxide (O2-), hydrogen peroxide (H2O2), and hydroxyl radicals (.OH), which may be responsible for the toxicity of C. marina. In this study, we found the other raphidophycean flagellates such as Heterosigma akashiwo, Olisthodiscus luteus, and Fibrocapsa japonica also produce O2- and H2O2 under normal growth condition. Among the flagellate species tested, Chattonella has the highest rates of production of O2- and H2O2 as compared on the basis of cell number. This seems to be partly due to differences in their cell sizes, since Chattonella is larger than other flagellate species. The generation of O2- by these flagellate species was also confirmed by a chemiluminescence assay by using 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo[1,2-a]pyrazin++ +-3-one (MCLA). All these raphidophycean flagellates inhibited the proliferation of a marine bacterium, Vibrio alginolyticus, in a flagellates/bacteria co-culture system, and their toxic effects were suppressed by the addition of superoxide dismutase (SOD) or catalase. Our results suggest that the generation of reactive oxygen species is a common feature of raphidophycean flagellates.

  14. Catalytic reduction of NO by CO over rhodium catalysts. 2. Effect of oxygen on the nature, population, and reactivity of surface species formed under reaction conditions

    SciTech Connect

    Kondarides, D.I.; Chafik, T.; Verykios, X.E.

    2000-04-01

    The effect of oxygen on the nature, population, and reactivity of surface species formed during reduction of NO by CO over Rh/TiO{sub 2} catalysts has been examined employing FTIR and transient MS techniques. It has been found that the activity of Rh is hindered by accumulation of surface oxygen originating from NO decomposition and gas-phase oxygen in the feed. Adsorbed CO and reduced TiO{sub 2{minus}x} species in the vicinity of Rh particles act as oxygen atom scavengers and, under fuel-rich conditions, remove atomic oxygen from the surface and restore the catalytic properties. Results of the present study provide additional evidence that production of N{sub 2} is related to dissociation of adsorbed Rh-NO{sup {minus}} while production of N{sub 2}O is related to the presence of Rh(NO){sub 2}. The presence of reduced RH{sup 0} sites is necessary for the formation of both reduction products. In the absence of oxygen in the feed, surface isocyanate species are also observed under reaction conditions. Their formation requires the presence of adjacent Rh{sup 0}-CO and reduced Rh{sup 0} sites. Although these species are favored under conditions in which NO conversion to reduction products is observed, there is no evidence that they are catalytically active species.

  15. Reactive oxygen species and the free radical theory of aging.

    PubMed

    Liochev, Stefan I

    2013-07-01

    The traditional view in the field of free radical biology is that free radicals and reactive oxygen species (ROS) are toxic, mostly owing to direct damage of sensitive and biologically significant targets, and are thus a major cause of oxidative stress; that complex enzymatic and nonenzymatic systems act in concert to counteract this toxicity; and that a major protective role is played by the phenomenon of adaptation. Another part of the traditional view is that the process of aging is at least partly due to accumulated damage done by these harmful species. However, recent workers in this and in related fields are exploring the view that superoxide radical and reactive oxygen species exert beneficial effects. Thus, such ROS are viewed as involved in cellular regulation by acting as (redox) signals, and their harmful effects are seen mostly as a result of compromised signaling, rather than due to direct damage to sensitive targets. According to some followers of this view, ROS such as hydrogen peroxide and superoxide are not just causative agents of aging but may also be agents that increase the life span by acting, for example, as prosurvival signals. The goal of this review is to recall that many of the effects of ROS that are interpreted as beneficial may actually represent adaptations to toxicity and that some of the most extravagant recent claims may be due to misinterpretation, oversimplification, and ignoring the wealth of knowledge supporting the traditional view. Whether it is time to abandon the free radical (oxidative stress) theory of aging is considered.

  16. Decreases in mitochondrial reactive oxygen species initiate GABAA receptor-mediated electrical suppression in anoxia-tolerant turtle neurons

    PubMed Central

    Hogg, David W; Pamenter, Matthew E; Dukoff, David J; Buck, Leslie T

    2015-01-01

    Key points Anoxia induces hyper-excitability and cell death in mammalian brain but in the western painted turtle (Chrysemys picta bellii) enhanced GABA transmission prevents injury. The mechanism responsible for increased GABA transmission is unknown; however, reactive oxygen species (ROS) generated by mitochondria may play a role because this is an oxygen-sensitive process. In this study, we show that inhibition of mitochondrial ROS production is sufficient to initiate a redox-sensitive GABA signalling cascade that suppresses pyramidal neuron action potential frequency. These results further our understanding of the turtle's unique strategy for reducing ATP consumption during anoxia and highlights a natural mechanism in which to explore therapies to protect mammalian brain from low-oxygen insults (e.g. cerebral stroke). Abstract Anoxia induces hyper-excitability and cell death in mammalian brain but in the anoxia-tolerant western painted turtle (Chrysemys picta bellii) neuronal electrical activity is suppressed (i.e. spike arrest), adenosine triphosphate (ATP) consumption is reduced, and cell death does not occur. Electrical suppression is primarily the result of enhanced γ-aminobutyric acid (GABA) transmission; however, the underlying mechanism responsible for initiating oxygen-sensitive GABAergic spike arrest is unknown. In turtle cortical pyramidal neurons there are three types of GABAA receptor-mediated currents: spontaneous inhibitory postsynaptic currents (IPSCs), giant IPSCs and tonic currents. The aim of this study was to assess the effects of reactive oxygen species (ROS) scavenging on these three currents since ROS levels naturally decrease with anoxia and may serve as a redox signal to initiate spike arrest. We found that anoxia, pharmacological ROS scavenging, or inhibition of mitochondrial ROS generation enhanced all three types of GABA currents, with tonic currents comprising ∼50% of the total current. Application of hydrogen peroxide inhibited

  17. Inhibition of reactive oxygen species in hypothalamic paraventricular nucleus attenuates the renin–angiotensin system and proinflammatory cytokines in hypertension

    SciTech Connect

    Su, Qing; Qin, Da-Nian; Wang, Fu-Xin; Ren, Jun; Li, Hong-Bao; Zhang, Meng; Yang, Qing; Miao, Yu-Wang; Yu, Xiao-Jing; Qi, Jie; Zhu, Zhiming; Zhu, Guo-Qing; Kang, Yu-Ming

    2014-04-15

    Aims: To explore whether reactive oxygen species (ROS) scavenger (tempol) in the hypothalamic paraventricular nucleus (PVN) attenuates renin–angiotensin system (RAS) and proinflammatory cytokines (PICs), and decreases the blood pressure and sympathetic activity in angiotensin II (ANG II)-induced hypertension. Methods and results: Male Sprague–Dawley rats were infused intravenously with ANG II (10 ng/kg per min) or normal saline (NS) for 4 weeks. These rats were treated with bilateral PVN infusion of oxygen free radical scavenger tempol (TEMP, 20 μg/h) or vehicle (artificial cerebrospinal fluid, aCSF) for 4 weeks. ANG II infusion resulted in increased mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA). These ANG II-infused rats also had higher levels of gp91{sup phox} (a subunit of NAD(P)H oxidase), angiotensin-converting enzyme (ACE), and interleukin-1beta (IL-1β) in the PVN than the control animals. Treatment with PVN infusion of TEMP attenuated the overexpression of gp91{sup phox}, ACE and IL-1β within the PVN, and decreased sympathetic activity and MAP in ANG II-infused rats. Conclusion: These findings suggest that ANG II infusion induces elevated PICs and oxidative stress in the PVN, which contribute to the sympathoexcitation in hypertension. Inhibition of reactive oxygen species in hypothalamic paraventricular nucleus attenuates the renin–angiotensin system, proinflammatory cytokines and oxidative stress in ANG II-induced hypertension. - Highlights: • The effect of chronic inhibiting PVN superoxide on hypertension was investigated. • ANG II infusion induced increased proinflammatory cytokines and superoxide in PVN. • ANG II infusion resulted in oxidative stress, sympathoexcitation and hypertension. • Chronic inhibiting PVN superoxide attenuates RAS and cytokines in hypertension.

  18. C-phycocyanin protects against low fertility by inhibiting reactive oxygen species in aging mice.

    PubMed

    Li, Yan-Jiao; Han, Zhe; Ge, Lei; Zhou, Cheng-Jie; Zhao, Yue-Fang; Wang, Dong-Hui; Ren, Jing; Niu, Xin-Xin; Liang, Cheng-Guang

    2016-04-05

    Women over 35 have higher rates of infertility, largely due to deterioration of oocyte quality characterized by fragmentation, abnormal meiotic spindle-chromosome complexes, and oxidative stress. C-phycocyanin (PC) is a biliprotein enriched in Spirulina platensis that is known to possess antioxidant, anti-inflammatory, and radical-scavenging properties. D-galactose-induced aging acceleration in mice has been extensively used to study aging mechanisms and for pharmaceutical screening. In this study, adult female B6D2F/1 mice injected with D-galactose were used as a model to test the age-reversing effects of PC on degenerated reproductive ability. Our results show that PC can prevent oocyte fragmentation and aneuploidy by maintaining cytoskeletal integrity. Moreover, PC can reverse the expression of antioxidant genes, increase superoxide dismutase (SOD) activity and decrease methane dicarboxylic aldehyde (MDA) content, and normalize mitochondria distribution. PC exerts its benefit by inhibiting reactive oxygen species (ROS) production, which decreases apoptosis. Finally, we observe a significant increase in litter size after PC administration to D-galactose-induced aging mice. Our study demonstrates for the first time that D-galactose-induced impaired female reproductive capability can be partially rescued by the antioxidant effects of PC.

  19. Extracellular ultrathin fibers sensitive to intracellular reactive oxygen species: Formation of intercellular membrane bridges

    SciTech Connect

    Jung, Se-Hui; Park, Jin-Young; Joo, Jung-Hoon; Kim, Young-Myeong; Ha, Kwon-Soo

    2011-07-15

    Membrane bridges are key cellular structures involved in intercellular communication; however, dynamics for their formation are not well understood. We demonstrated the formation and regulation of novel extracellular ultrathin fibers in NIH3T3 cells using confocal and atomic force microscopy. At adjacent regions of neighboring cells, phorbol 12-myristate 13-acetate (PMA) and glucose oxidase induced ultrathin fiber formation, which was prevented by Trolox, a reactive oxygen species (ROS) scavenger. The height of ROS-sensitive ultrathin fibers ranged from 2 to 4 nm. PMA-induced formation of ultrathin fibers was inhibited by cytochalasin D, but not by Taxol or colchicine, indicating that ultrathin fibers mainly comprise microfilaments. PMA-induced ultrathin fibers underwent dynamic structural changes, resulting in formation of intercellular membrane bridges. Thus, these fibers are formed by a mechanism(s) involving ROS and involved in formation of intercellular membrane bridges. Furthermore, ultrastructural imaging of ultrathin fibers may contribute to understanding the diverse mechanisms of cell-to-cell communication and the intercellular transfer of biomolecules, including proteins and cell organelles.

  20. Nutritional Countermeasures Targeting Reactive Oxygen Species in Cancer: From Mechanisms to Biomarkers and Clinical Evidence

    PubMed Central

    Samoylenko, Anatoly; Hossain, Jubayer Al; Mennerich, Daniela; Kellokumpu, Sakari; Hiltunen, Jukka Kalervo

    2013-01-01

    Abstract Reactive oxygen species (ROS) exert various biological effects and contribute to signaling events during physiological and pathological processes. Enhanced levels of ROS are highly associated with different tumors, a Western lifestyle, and a nutritional regime. The supplementation of food with traditional antioxidants was shown to be protective against cancer in a number of studies both in vitro and in vivo. However, recent large-scale human trials in well-nourished populations did not confirm the beneficial role of antioxidants in cancer, whereas there is a well-established connection between longevity of several human populations and increased amount of antioxidants in their diets. Although our knowledge about ROS generators, ROS scavengers, and ROS signaling has improved, the knowledge about the direct link between nutrition, ROS levels, and cancer is limited. These limitations are partly due to lack of standardized reliable ROS measurement methods, easily usable biomarkers, knowledge of ROS action in cellular compartments, and individual genetic predispositions. The current review summarizes ROS formation due to nutrition with respect to macronutrients and antioxidant micronutrients in the context of cancer and discusses signaling mechanisms, used biomarkers, and its limitations along with large-scale human trials. Antioxid. Redox Signal. 19, 2157–2196. PMID:23458328

  1. Photoreactivity of Metal-Organic Frameworks in Aqueous Solutions: Metal Dependence of Reactive Oxygen Species Production.

    PubMed

    Liu, Kai; Gao, Yanxin; Liu, Jing; Wen, Yifan; Zhao, Yingcan; Zhang, Kunyang; Yu, Gang

    2016-04-05

    Promising applications of metal-organic frameworks (MOFs) in various fields have raised concern over their environmental fate and safety upon inevitable discharge into aqueous environments. Currently, no information regarding the transformation processes of MOFs is available. Due to the presence of repetitive π-bond structure and semiconductive property, photochemical transformations are an important fate process that affects the performance of MOFs in practical applications. In the current study, the generation of reactive oxygen species (ROS) in isoreticular MIL-53s was studied. Scavengers were employed to probe the production of (1)O2, O2(•-), and •OH, respectively. In general, MIL-53(Cr) and MIL-53(Fe) are dominated by type I and II photosensitization reactions, respectively, and MIL-53(Al) appears to be less photoreactive. The generation of ROS in MIL-53(Fe) may be underestimated due to dismutation. Further investigation of MIL-53(Fe) encapsulated diclofenac transformation revealed that diclofenac can be easily transformed by MIL-53(Fe) generated ROS. However, the cytotoxicity results implied that the ROS generated from MIL-53s have little effect on the viability of the human hepatocyte (HepG2) cell line. These results suggest that the photogeneration of ROS by MOFs may be metal-node dependent, and the application of MIL-53s as drug carriers needs to be carefully considered due to their high photoreactivity.

  2. Fine tuning of reactive oxygen species homeostasis regulates primed immune responses in Arabidopsis.

    PubMed

    Pastor, Victoria; Luna, Estrella; Ton, Jurriaan; Cerezo, Miguel; García-Agustín, Pilar; Flors, Victor

    2013-11-01

    Selected stimuli can prime the plant immune system for a faster and stronger defense reaction to pathogen attack. Pretreatment of Arabidopsis with the chemical agent β-aminobutyric acid (BABA) augmented H2O2 and callose production after induction with the pathogen-associated molecular pattern (PAMP) chitosan, or inoculation with the necrotrophic fungus Plectosphaerella cucumerina. However, BABA failed to prime H2O2 and callose production after challenge with the bacterial PAMP Flg22. Analysis of Arabidopsis mutants in reactive oxygen species (ROS) production (rbohD) or ROS scavenging (pad2, vtc1, and cat2) suggested a regulatory role for ROS homeostasis in priming of chitosan- and P. cucumerina-inducible callose and ROS. Moreover, rbohD and pad2 were both impaired in BABA-induced resistance against P. cucumerina. Gene expression analysis revealed direct induction of NADPH/respiratory burst oxidase protein D (RBOHD), γ-glutamylcysteine synthetase 1 (GSH1), and vitamin C defective 1 (VTC1) genes after BABA treatment. Conversely, ascorbate peroxidase 1 (APX1) transcription was repressed by BABA after challenge with chitosan or P. cucumerina, probably to provide a more oxidized environment in the cell and facilitate augmented ROS accumulation. Measuring ratios between reduced and oxidized glutathione confirmed that augmented defense expression in primed plants is associated with a more oxidized cellular status. Together, our data indicate that an altered ROS equilibrium is required for augmented defense expression in primed plants.

  3. Synergistic triggering of superoxide flashes by mitochondrial Ca2+ uniport and basal reactive oxygen species elevation.

    PubMed

    Hou, Tingting; Zhang, Xing; Xu, Jiejia; Jian, Chongshu; Huang, Zhanglong; Ye, Tao; Hu, Keping; Zheng, Ming; Gao, Feng; Wang, Xianhua; Cheng, Heping

    2013-02-15

    Mitochondrial superoxide flashes reflect a quantal, bursting mode of reactive oxygen species (ROS) production that arises from stochastic, transient opening of the mitochondrial permeability transition pore (mPTP) in many types of cells and in living animals. However, the regulatory mechanisms and the exact nature of the flash-coupled mPTP remain poorly understood. Here we demonstrate a profound synergistic effect between mitochondrial Ca(2+) uniport and elevated basal ROS production in triggering superoxide flashes in intact cells. Hyperosmotic stress potently augmented the flash activity while simultaneously elevating mitochondrial Ca(2+) and ROS. Blocking mitochondrial Ca(2+) transport by knockdown of MICU1 or MCU, newly identified components of the mitochondrial Ca(2+) uniporter, or scavenging mitochondrial basal ROS markedly diminished the flash response. More importantly, whereas elevating Ca(2+) or ROS production alone was inefficacious in triggering the flashes, concurrent physiological Ca(2+) and ROS elevation served as the most powerful flash activator, increasing the flash incidence by an order of magnitude. Functionally, superoxide flashes in response to hyperosmotic stress participated in the activation of JNK and p38. Thus, physiological levels of mitochondrial Ca(2+) and ROS synergistically regulate stochastic mPTP opening and quantal ROS production in intact cells, marking the flash as a coincidence detector of mitochondrial Ca(2+) and ROS signals.

  4. Reactive oxygen species in Hevea brasiliensis latex and relevance to Tapping Panel Dryness.

    PubMed

    Zhang, Yi; Leclercq, Julie; Montoro, Pascal

    2016-11-29

    Environmental stress can lead to oxidative stress resulting from an increase in reactive oxygen species (ROS) and involves redox adjustments. Natural rubber is synthesized in laticifers, which is a non-photosynthetic tissue particularly prone to oxidative stress. This paper reviews the current state of knowledge on the ROS production and ROS-scavenging systems in laticifers. These regulations have been the subject of intense research into a physiological syndrome, called Tapping Panel Dryness (TPD), affecting latex production in Hevea brasiliensis In order to prevent TPD occurrence, monitoring thiol content appeared to be a crucial factor of latex diagnosis. Thiols, ascorbate and γ-tocotrienol are the major antioxidants in latex. They are involved in membrane protection from ROS and likely have an effect on the quality of raw rubber. Some transcription factors might play a role in the redox regulatory network in Hevea, in particular ethylene response factors, which have been the most intensively studied given the role of ethylene on rubber production. Current challenges for rubber research and development with regard to redox systems will involve improving antioxidant capacity using natural genetic variability.

  5. Reactive oxygen species do not contribute to ObgE*-mediated programmed cell death

    PubMed Central

    Dewachter, Liselot; Herpels, Pauline; Verstraeten, Natalie; Fauvart, Maarten; Michiels, Jan

    2016-01-01

    Programmed cell death (PCD) in bacteria is considered an important target for developing novel antimicrobials. Development of PCD-specific therapies requires a deeper understanding of what drives this process. We recently discovered a new mode of PCD in Escherichia coli that is triggered by expression of a mutant isoform of the essential ObgE protein, ObgE*. Our previous findings demonstrate that ObgE*-mediated cell death shares key characteristics with apoptosis in eukaryotic cells. It is well-known that reactive oxygen species (ROS) are formed during PCD in eukaryotes and play a pivotal role as signaling molecules in the progression of apoptosis. Therefore, we explored a possible role for ROS in bacterial killing by ObgE*. Using fluorescent probes and genetic reporters, we found that expression of ObgE* induces formation of ROS. Neutralizing ROS by chemical scavenging or by overproduction of ROS-neutralizing enzymes did not influence toxicity of ObgE*. Moreover, expression of ObgE* under anaerobic conditions proved to be as detrimental to bacterial viability as expression under aerobic conditions. In conclusion, ROS are byproducts of ObgE* expression that do not play a role in the execution or progression of ObgE*-mediated PCD. Targeted therapies should therefore look to exploit other aspects of ObgE*-mediated PCD. PMID:27641546

  6. Francisella tularensis Antioxidants Harness Reactive Oxygen Species to Restrict Macrophage Signaling and Cytokine Production*

    PubMed Central

    Melillo, Amanda A.; Bakshi, Chandra Shekhar; Melendez, J. Andrés

    2010-01-01

    Francisella tularensis is the etiologic agent of the highly infectious animal and human disease tularemia. Its extreme infectivity and virulence are associated with its ability to evade immune detection, which we now link to its robust reactive oxygen species-scavenging capacity. Infection of primary human monocyte-derived macrophages with virulent F. tularensis SchuS4 prevented proinflammatory cytokine production in the presence or absence of IFN-γ compared with infection with the attenuated live vaccine strain. SchuS4 infection also blocked signals required for macrophage cytokine production, including Akt phosphorylation, IκBα degradation, and NF-κB nuclear localization and activation. Concomitant with SchuS4-mediated suppression of Akt phosphorylation was an increase in the levels of the Akt antagonist PTEN. Moreover, SchuS4 prevented the H2O2-dependent oxidative inactivation of PTEN compared with a virulent live vaccine strain. Mutation of catalase (katG) sensitized F. tularensis to H2O2 and enhanced PTEN oxidation, Akt phosphorylation, NF-κB activation, and inflammatory cytokine production. Together, these findings suggest a novel role for bacterial antioxidants in restricting macrophage activation through their ability to preserve phosphatases that temper kinase signaling and proinflammatory cytokine production. PMID:20558723

  7. Negative Regulation of Autophagy by Sulfide Is Independent of Reactive Oxygen Species.

    PubMed

    Laureano-Marín, Ana M; Moreno, Inmaculada; Romero, Luis C; Gotor, Cecilia

    2016-06-01

    Accumulating experimental evidence in mammalian, and recently plant, systems has led to a change in our understanding of the role played by hydrogen sulfide in life processes. In plants, hydrogen sulfide mitigates stress and regulates important plant processes such as photosynthesis, stomatal movement, and autophagy, although the underlying mechanism is not well known. In this study, we provide new experimental evidence that, together with our previous findings, demonstrates the role of hydrogen sulfide in regulating autophagy. We used green fluorescent protein fluorescence associated with autophagic bodies and immunoblot analysis of the ATG8 protein to show that sulfide (and no other molecules such as sulfur-containing molecules or ammonium) was able to inhibit the autophagy induced in Arabidopsis (Arabidopsis thaliana) roots under nitrogen deprivation. Our results showed that sulfide was unable to scavenge reactive oxygen species generated by nitrogen limitation, in contrast to well-established reducers. In addition, reducers were unable to inhibit the accumulation of autophagic bodies and ATG8 protein forms to the same extent as sulfide. Therefore, we conclude that sulfide represses autophagy via a mechanism that is independent of redox conditions.

  8. Reactive Oxygen Species Regulate T Cell Immune Response in the Tumor Microenvironment

    PubMed Central

    Chen, Xinfeng; Song, Mengjia

    2016-01-01

    Reactive oxygen species (ROS) produced by cellular metabolism play an important role as signaling messengers in immune system. ROS elevated in the tumor microenvironment are associated with tumor-induced immunosuppression. T cell-based therapy has been recently approved to be effective for cancer treatment. However, T cells often become dysfunctional after reaching the tumor site. It has been reported that ROS participate extensively in T cells activation, apoptosis, and hyporesponsiveness. The sensitivity of T cells to ROS varies among different subsets. ROS can be regulated by cytokines, amino acid metabolism, and enzymatic activity. Immunosuppressive cells accumulate in the tumor microenvironment and induce apoptosis and functional suppression of T cells by producing ROS. Thus, modulating the level of ROS may be important to prolong survival of T cells and enhance their antitumor function. Combining T cell-based therapy with antioxidant treatment such as administration of ROS scavenger should be considered as a promising strategy in cancer treatment, aiming to improve antitumor T cells immunity. PMID:27547291

  9. High cell density attenuates reactive oxygen species: implications for in vitro assays.

    PubMed

    Kim, Dennis P; Yahav, Jonathan; Sperandeo, Michael; Maloney, Lauren; McTigue, Monica; Lin, Fubao; Clark, Richard A F

    2012-01-01

    In vitro cell-based assays are an essential and universally used step in elucidation of biological processes as well as in drug development. However, results obtained depend on the validity of protocols used. This statement certainly pertains to in vitro assays of oxidative stress. The holy grail of in vitro models is reliability and predictability of outcomes that relate to a single variable like addition of hydrogen peroxide or xanthine oxidase. Without such validated outcomes, comparison of results among different laboratories is not possible. Achieving this goal requires a thorough understanding of the complex interplay between the cells, their environment, and the experimental assays. Furthermore, as this knowledge is attained, it must be disseminated and used to update and standardize existing protocols. Here, we confirm and extend the effect of pyruvate and cell density on in vitro oxidative stress assays. Cell viability was assessed using a colorimetric assay measuring the reduction of a tetrazolium salt (XTT) into a colored formazan dye. Extracellular hydrogen peroxide concentrations were measured using the foxp3 assay. We confirmed a previously reported finding that pyruvate, a common ingredient in cell culture media, acts as an extracellular scavenger of reactive oxygen species. We also demonstrated that cell density directly correlates with resistance to oxidative stress in tissue culture. It is theorized that the protective effect due to cell density predominantly relates to intracellular factors such as reduced glutathione and extracellular factors such as catalase.

  10. Silver nanoparticles affect glucose metabolism in hepatoma cells through production of reactive oxygen species

    PubMed Central

    Lee, Mi Jin; Lee, Seung Jun; Yun, Su Jin; Jang, Ji-Young; Kang, Hangoo; Kim, Kyongmin; Choi, In-Hong; Park, Sun

    2016-01-01

    The silver nanoparticle (AgNP) is a candidate for anticancer therapy because of its effects on cell survival and signaling. Although numerous reports are available regarding their effect on cell death, the effect of AgNPs on metabolism is not well understood. In this study, we investigated the effect of AgNPs on glucose metabolism in hepatoma cell lines. Lactate release from both HepG2 and Huh7 cells was reduced with 5 nm AgNPs as early as 1 hour after treatment, when cell death did not occur. Treatment with 5 nm AgNPs decreased glucose consumption in HepG2 cells but not in Huh7 cells. Treatment with 5 nm AgNPs reduced nuclear factor erythroid 2-like 2 expression in both cell types without affecting its activation at the early time points after AgNPs’ treatment. Increased reactive oxygen species (ROS) production was detected 1 hour after 5 nm AgNPs’ treatment, and lactate release was restored in the presence of an ROS scavenger. Our results suggest that 5 nm AgNPs affect glucose metabolism by producing ROS. PMID:26730190

  11. Cadmium induces apoptosis and genotoxicity in rainbow trout hepatocytes through generation of reactive oxygene species.

    PubMed

    Risso-de Faverney, C; Devaux, A; Lafaurie, M; Girard, J P; Bailly, B; Rahmani, R

    2001-06-01

    Cadmium poses a serious environmental threat in aquatic ecosystems but the mechanisms of its toxicity remain unclear. The purpose of this work was first to determine whether cadmium induced apoptosis in trout hepatocytes, second to determine whether or not reactive oxygen species (ROS) were involved in cadmium-induced apoptosis and genotoxicity. Hepatocytes exposed to increasing cadmium concentrations (in the range of 1-10 microM) showed a molecular hallmark of apoptosis which is the fragmentation of the nuclear DNA into oligonucleosomal-length fragments, resulting from an activation of endogenous endonucleases and recognized as a 'DNA ladder' on conventional agarose gel electrophoresis. Exposure of hepatocytes to cadmium led clearly to the DEVD-dependent protease activation, acting upstream from the endonucleases and considered as central mediators of apoptosis. DNA strand breaks in cadmium-treated trout hepatocytes was assessed using the comet assay, a rapid and sensitive single-cell gel electrophoresis technique used to detect DNA primary damage in individual cells. Simultaneous treatment of trout hepatocytes with cadmium and the nitroxide radical TEMPO used as a ROS scavenger, reduced significantly DNA fragmentation, DEVD-related protease activity and DNA strand breaks formation. These results lead to a working hypothesis that cadmium-induced apoptosis and DNA strand breaks in trout hepatocytes are partially triggered by the generation of ROS. Additional studies are required for proposing a mechanistic model of cadmium-induced apoptosis and genotoxicity in trout liver cells, in underlying the balance between DNA damage and cellular defence systems in fish.

  12. Silver nanoparticles affect glucose metabolism in hepatoma cells through production of reactive oxygen species.

    PubMed

    Lee, Mi Jin; Lee, Seung Jun; Yun, Su Jin; Jang, Ji-Young; Kang, Hangoo; Kim, Kyongmin; Choi, In-Hong; Park, Sun

    2016-01-01

    The silver nanoparticle (AgNP) is a candidate for anticancer therapy because of its effects on cell survival and signaling. Although numerous reports are available regarding their effect on cell death, the effect of AgNPs on metabolism is not well understood. In this study, we investigated the effect of AgNPs on glucose metabolism in hepatoma cell lines. Lactate release from both HepG2 and Huh7 cells was reduced with 5 nm AgNPs as early as 1 hour after treatment, when cell death did not occur. Treatment with 5 nm AgNPs decreased glucose consumption in HepG2 cells but not in Huh7 cells. Treatment with 5 nm AgNPs reduced nuclear factor erythroid 2-like 2 expression in both cell types without affecting its activation at the early time points after AgNPs' treatment. Increased reactive oxygen species (ROS) production was detected 1 hour after 5 nm AgNPs' treatment, and lactate release was restored in the presence of an ROS scavenger. Our results suggest that 5 nm AgNPs affect glucose metabolism by producing ROS.

  13. Autophagy induction upon reactive oxygen species in Cd-stressed Arabidopsis thaliana

    NASA Astrophysics Data System (ADS)

    Zhang, WeiNa; Chen, WenLi

    2010-02-01

    Autophagy is a protein degradation process in which cells recycle cytoplasmic contents when subjected to environmental stress conditions or during certain stages of development. Upon the induction of autophagy, a double membrane autophagosome forms around cytoplasmic components and delivers them to the vacuole for degradation. In plants, autophagy has been shown previously to be induced during abiotic stresses including oxidative stress. Cd, as a toxicity heavy metal, resulted in the production of reactive oxygen species (ROS). In this paper, we demonstrated that ROS contributed to the induction of autophagy in Cd-stressed Arabidopsis thaliana. However, pre-incubation with ascorbic acid (AsA, antioxidant molecule) and catalase (CAT, a H2O2-specific scavenger) decreased the ROS production and the number of autolysosomal-like structures. Together our results indicated that the oxidative condition was essential for autophagy, as treatment with AsA and CAT abolished the formation of autophagosomes, and ROS may function as signal molecules to induce autophagy in abiotic stress.

  14. Emerging roots alter epidermal cell fate through mechanical and reactive oxygen species signaling.

    PubMed

    Steffens, Bianka; Kovalev, Alexander; Gorb, Stanislav N; Sauter, Margret

    2012-08-01

    A central question in biology is how spatial information is conveyed to locally establish a developmental program. Rice (Oryza sativa) can survive flash floods by the emergence of adventitious roots from the stem. Epidermal cells that overlie adventitious root primordia undergo cell death to facilitate root emergence. Root growth and epidermal cell death are both controlled by ethylene. This study aimed to identify the signal responsible for the spatial control of cell death. Epidermal cell death correlated with the proximity to root primordia in wild-type and ADVENTITIOUS ROOTLESS1 plants, indicating that the root emits a spatial signal. Ethylene-induced root growth generated a mechanical force of ~18 millinewtons within 1 h. Force application to epidermal cells above root primordia caused cell death in a dose-dependent manner and was inhibited by 1-methylcyclopropene or diphenylene iodonium, an inhibitor of NADPH oxidase. Exposure of epidermal cells not overlying a root to either force and ethylene or force and the catalase inhibitor aminotriazole induced ectopic cell death. Genetic downregulation of the reactive oxygen species (ROS) scavenger METALLOTHIONEIN2b likewise promoted force-induced ectopic cell death. Hence, reprogramming of epidermal cell fate by the volatile plant hormone ethylene requires two signals: mechanosensing for spatial resolution and ROS for cell death signaling.

  15. Impact of reactive oxygen species generation on Helicobacter pylori-related extragastric diseases: a hypothesis.

    PubMed

    Kountouras, Jannis; Boziki, Marina; Polyzos, Stergios A; Katsinelos, Panagiotis; Gavalas, Emmanouel; Zeglinas, Christos; Tzivras, Dimitri; Romiopoulos, Iordanis; Giorgakis, Nikolaos; Anastasiadou, Kyriaki; Vardaka, Elizabeth; Kountouras, Constantinos; Kazakos, Evangelos; Xiromerisiou, Georgia; Dardiotis, Efthimios; Deretzi, Georgia

    2017-01-01

    Helicobacter pylori (H. pylori) induces reactive oxygen species (ROS) production that contribute to pathogenesis of a variety of H. pylori-related gastric diseases, as shown in animal and human studies. Helicobacter pylori infection is also associated with variety of systemic extragastric diseases in which H. pylori-related ROS production might also be involved in the pathogenesis of these systemic conditions. We proposed that Hp-related ROS may play a crucial role in the pathophysiology of Hp-related systemic diseases including Alzheimer's disease, multiple sclerosis, glaucoma and other relative neurodegenerative diseases, thereby suggesting introduction of relative ROS scavengers as therapeutic strategies against these diseases which are among the leading causes of disability and are associated with a large public health global burden. Moreover, we postulated that H. pylori-related ROS might also be involved in the pathogenesis of extragastric common malignancies, thereby suggesting that H. pylori eradication might inhibit the development or delay the progression of aforementioned diseases. However, large-scale future studies are warranted to elucidate the proposed pathophysiological mechanisms, including H. pylori-related ROS, involved in H. pylori-associated systemic and malignant conditions.

  16. Reactive oxygen species and anti-oxidant defences in swine follicular fluids.

    PubMed

    Basini, Giuseppina; Simona, Bussolati; Santini, Sujen Eleonora; Grasselli, Francesca

    2008-01-01

    A growing body of evidence indicates that the pro-oxidant/anti-oxidant balance inside the ovarian follicle plays an important role in folliculogenesis. Therefore, the aim of the present study was to assess the redox status of follicular fluids collected from different-sized swine follicles. We quantified the most important reactive oxygen species (ROS), namely superoxide anion (O(2)(-)), hydrogen peroxide and hydroperoxides (ROOH); in addition, we examined the activity of the detoxifying enzymes superoxide dismutase, catalase (CAT) and glutathione peroxidase and the total non-enzymatic antioxidant capacity as determined by the ferric-reducing anti-oxidant power assay. Our data demonstrate that oxidative stress does not affect follicle growth because O(2)(-) levels do not change during follicle development, whereas concentrations of H2O2 and ROOH are reduced (P < 0.05). Surprisingly, all non-enzymatic and enzymatic scavengers examined in the present study, except for CAT, demonstrated reduced activity during follicle development (P < 0.05). Taken together, these results suggest that other factors could be involved in ROS detoxification during follicle development.

  17. C-phycocyanin protects against low fertility by inhibiting reactive oxygen species in aging mice

    PubMed Central

    Li, Yan-Jiao; Han, Zhe; Ge, Lei; Zhou, Cheng-Jie; Zhao, Yue-Fang; Wang, Dong-Hui; Ren, Jing; Niu, Xin-Xin; Liang, Cheng-Guang

    2016-01-01

    Women over 35 have higher rates of infertility, largely due to deterioration of oocyte quality characterized by fragmentation, abnormal meiotic spindle-chromosome complexes, and oxidative stress. C-phycocyanin (PC) is a biliprotein enriched in Spirulina platensis that is known to possess antioxidant, anti-inflammatory, and radical-scavenging properties. D-galactose-induced aging acceleration in mice has been extensively used to study aging mechanisms and for pharmaceutical screening. In this study, adult female B6D2F/1 mice injected with D-galactose were used as a model to test the age-reversing effects of PC on degenerated reproductive ability. Our results show that PC can prevent oocyte fragmentation and aneuploidy by maintaining cytoskeletal integrity. Moreover, PC can reverse the expression of antioxidant genes, increase superoxide dismutase (SOD) activity and decrease methane dicarboxylic aldehyde (MDA) content, and normalize mitochondria distribution. PC exerts its benefit by inhibiting reactive oxygen species (ROS) production, which decreases apoptosis. Finally, we observe a significant increase in litter size after PC administration to D-galactose-induced aging mice. Our study demonstrates for the first time that D-galactose-induced impaired female reproductive capability can be partially rescued by the antioxidant effects of PC. PMID:27008700

  18. Emissions of volatile organic compounds (primarily oxygenated species) from pasture

    NASA Astrophysics Data System (ADS)

    Kirstine, Wayne; Galbally, Ian; Ye, Yuerong; Hooper, Martin

    1998-05-01

    The volatile organic compound (VOC) emissions from pasture at a site in southeastern Victoria, Australia, were monitored over a 2 year period using a static chamber technique. Fluxes up to 23,000 μg(C) m-2 h-1 were detected, with the higher fluxes originating from clover rather than from grass species. Gas Chromatographic analyses indicated that emissions from both grass and clover were high in oxygenated hydrocarbons including methanol, ethanol, propanone, butanone, and ethanal, and extremely low in isoprene and monoterpenes. In the case of clover, butanone made up 45-50% of the total emissions. When grass and clover were freshly mown, there were significantly enhanced emissions of VOCs. These enhanced emissions included both those oxygenates emitted from uncut pasture and also C6-oxygenates, including (Z)-3-hexenal, (E)-2-hexenal, (Z)-2-hexen-1-ol, (Z)-3-hexen-l-ol, and (Z)-3-hexenyl acetate. Emissions from the undisturbed pasture increased markedly with temperature and the intensity of solar radiation, peaking at midday and ceasing at night. The fluxes, when normalized to a temperature of 30°C and a light intensity of 1000 μE m-2 s-1 were, for grass and clover respectively, about one eighth and two fifths of the equivalent fluxes reported to occur from U.S. woodlands. The annual integrated emission from the pasture was approximately 1.9 g(C) m-2 or 1.3 mg(C) g-1 (dry matter). The large transient fluxes that occurred following physical damaging of the pasture, when integrated over time, could be of the same order as those emissions that were observed from undisturbed pasture. In the case of methanol, and perhaps ethanol, the emissions from grasslands may be significant global sources of these gases.

  19. Evidence for the Therapeutic Efficacy of Either Mild Hypothermia or Oxygen Radical Scavengers after Repetitive Mild Traumatic Brain Injury

    PubMed Central

    Miyauchi, Takashi; Wei, Enoch P.

    2014-01-01

    Abstract Repetitive brain injury, particularly that occurring with sporting-related injuries, has recently garnered increased attention in both the clinical and public settings. In the laboratory, we have demonstrated the adverse axonal and vascular consequences of repetitive brain injury and have demonstrated that moderate hypothermia and/or FK506 exerted protective effects after repetitive mild traumatic brain injury (mTBI) when administered within a specific time frame, suggesting a range of therapeutic modalities to prevent a dramatic exacerbation. In this communication, we revisit the utility of targeted therapeutic intervention to seek the minimal level of hypothermia needed to achieve protection while probing the role of oxygen radicals and their therapeutic targeting. Male Sprague-Dawley rats were subjected to repetitive mTBI by impact acceleration injury. Mild hypothermia (35°C, group 2), superoxide dismutase (group 3), and Tempol (group 4) were employed as therapeutic interventions administered 1 h after the repetitive mTBI. To assess vascular function, cerebral vascular reactivity to acetylcholine was evaluated 3 and 4 h after the repetitive mTBI, whereas to detect the burden of axonal damage, amyloid precursor protein (APP) density in the medullospinal junction was measured. Whereas complete impairment of vascular reactivity was observed in group 1 (without intervention), significant preservation of vascular reactivity was found in the other groups. Similarly, whereas remarkable increase in the APP-positive axon was observed in group 1, there were no significant increases in the other groups. Collectively, these findings indicate that even mild hypothermia or the blunting free radical damage, even when performed in a delayed period, is protective in repetitive mTBI. PMID:24341607

  20. Reactive Oxygen Species: A Key Hallmark of Cardiovascular Disease

    PubMed Central

    2016-01-01

    Cardiovascular diseases (CVDs) have been the prime cause of mortality worldwide for decades. However, the underlying mechanism of their pathogenesis is not fully clear yet. It has been already established that reactive oxygen species (ROS) play a vital role in the progression of CVDs. ROS are chemically unstable reactive free radicals containing oxygen, normally produced by xanthine oxidase, nicotinamide adenine dinucleotide phosphate oxidase, lipoxygenases, or mitochondria or due to the uncoupling of nitric oxide synthase in vascular cells. When the equilibrium between production of free radicals and antioxidant capacity of human physiology gets altered due to several pathophysiological conditions, oxidative stress is induced, which in turn leads to tissue injury. This review focuses on pathways behind the production of ROS, its involvement in various intracellular signaling cascades leading to several cardiovascular disorders (endothelial dysfunction, ischemia-reperfusion, and atherosclerosis), methods for its detection, and therapeutic strategies for treatment of CVDs targeting the sources of ROS. The information generated by this review aims to provide updated insights into the understanding of the mechanisms behind cardiovascular complications mediated by ROS. PMID:27774507

  1. [The role of reactive oxygen species and mitochondria in aging].

    PubMed

    Piotrowska, Agnieszka; Bartnik, Ewa

    2014-01-01

    Aging is a biological phenomenon concerning all living multicellular organisms. Many studies have been conducted to identify the mechanisms underlying this process. To date, multiple theories have been proposed to explain the causes of aging. One of them is the free radical theory which postulates that reactive oxygen species (ROS), extremely reactive chemical molecules, are the major cause of the aging process. These free radicals are mainly produced by the mitochondrial respiratory chain as a result of electron transport and the reduction of the oxygen molecule. Toxic effects of ROS on cellular components lead to accumulation of oxidative damage which causes cellular dysfunction with age. The free radical theory has been one of the most popular theories of aging for many years. Scientific research on different model organisms aiming to verify the theory has produced abundant data, supporting the theory or, on the contrary, suggesting strong evidence against it. At present, the free radical theory of aging is no longer considered to be true.

  2. Reactive oxygen species: A radical role in development?

    PubMed

    Hernández-García, David; Wood, Christopher D; Castro-Obregón, Susana; Covarrubias, Luis

    2010-07-15

    Reactive oxygen species (ROS), mostly derived from mitochondrial activity, can damage various macromolecules and consequently cause cell death. This ROS activity has been characterized in vitro, and correlative evidence suggests a role in various pathological conditions. In addition to this passive ROS activity, ROS also participate in cell signaling processes, though the relevance of this function in vivo is poorly understood. Throughout development, elevated cell activity is probably accompanied by highly active metabolism and, consequently, the production of large amounts of ROS. To allow proper development, cells must protect themselves from these potentially damaging ROS. However, to what degree ROS could participate as signaling molecules controlling fundamental and developmentally relevant cellular processes such as proliferation, differentiation, and death is an open question. Here we discuss why available data do not yet provide conclusive evidence on the role of ROS in development, and we review recent methods to detect ROS in vivo and genetic strategies that can be exploited specifically to resolve these uncertainties.

  3. Reactive Oxygen Species in the Regulation of Stomatal Movements.

    PubMed

    Sierla, Maija; Waszczak, Cezary; Vahisalu, Triin; Kangasjärvi, Jaakko

    2016-07-01

    Guard cells form stomatal pores that optimize photosynthetic carbon dioxide uptake with minimal water loss. Stomatal movements are controlled by complex signaling networks that respond to environmental and endogenous signals. Regulation of stomatal aperture requires coordinated activity of reactive oxygen species (ROS)-generating enzymes, signaling proteins, and downstream executors such as ion pumps, transporters, and plasma membrane channels that control guard cell turgor pressure. Accumulation of ROS in the apoplast and chloroplasts is among the earliest hallmarks of stomatal closure. Subsequent increase in cytoplasmic Ca(2+) concentration governs the activity of multiple kinases that regulate the activity of ROS-producing enzymes and ion channels. In parallel, ROS directly regulate the activity of multiple proteins via oxidative posttranslational modifications to fine-tune guard cell signaling. In this review, we summarize recent advances in the role of ROS in stomatal closure and discuss the importance of ROS in regulation of signal amplification and specificity in guard cells.

  4. Reactive oxygen species in eradicating acute myeloid leukemic stem cells

    PubMed Central

    Zhang, Hui; Fang, Hai

    2014-01-01

    Leukemic stem cells (LSCs) have been proven to drive leukemia initiation, progression and relapse, and are increasingly being used as a critical target for therapeutic intervention. As an essential feature in LSCs, reactive oxygen species (ROS) homeostasis has been extensively exploited in the past decade for targeting LSCs in acute myeloid leukemia (AML). Most, if not all, agents that show therapeutic benefits are able to alter redox status by inducing ROS, which confers selectivity in eradicating AML stem cells but sparing normal counterparts. In this review, we provide the comprehensive update of ROS-generating agents in the context of their impacts on our understanding of the pathogenesis of AML and its therapy. We anticipate that further characterizing these ROS agents will help us combat against AML in the coming era of LSC-targeting strategy. PMID:27358859

  5. Reactive oxygen species-activated nanomaterials as theranostic agents

    PubMed Central

    Kim, Kye S; Lee, Dongwon; Song, Chul Gyu; Kang, Peter M

    2015-01-01

    Reactive oxygen species (ROS) are generated from the endogenous oxidative metabolism or from exogenous pro-oxidant exposure. Oxidative stress occurs when there is excessive production of ROS, outweighing the antioxidant defense mechanisms which may lead to disease states. Hydrogen peroxide (H2O2) is one of the most abundant and stable forms of ROS, implicated in inflammation, cellular dysfunction and apoptosis, which ultimately lead to tissue and organ damage. This review is an overview of the role of ROS in different diseases. We will also examine ROS-activated nanomaterials with emphasis on hydrogen peroxide, and their potential medical implications. Further development of the biocompatible, stimuli-activated agent responding to disease causing oxidative stress, may lead to a promising clinical use. PMID:26328770

  6. Reactive Oxygen Species: Physiological and Physiopathological Effects on Synaptic Plasticity

    PubMed Central

    Beckhauser, Thiago Fernando; Francis-Oliveira, José; De Pasquale, Roberto

    2016-01-01

    In the mammalian central nervous system, reactive oxygen species (ROS) generation is counterbalanced by antioxidant defenses. When large amounts of ROS accumulate, antioxidant mechanisms become overwhelmed and oxidative cellular stress may occur. Therefore, ROS are typically characterized as toxic molecules, oxidizing membrane lipids, changing the conformation of proteins, damaging nucleic acids, and causing deficits in synaptic plasticity. High ROS concentrations are associated with a decline in cognitive functions, as observed in some neurodegenerative disorders and age-dependent decay of neuroplasticity. Nevertheless, controlled ROS production provides the optimal redox state for the activation of transductional pathways involved in synaptic changes. Since ROS may regulate neuronal activity and elicit negative effects at the same time, the distinction between beneficial and deleterious consequences is unclear. In this regard, this review assesses current research and describes the main sources of ROS in neurons, specifying their involvement in synaptic plasticity and distinguishing between physiological and pathological processes implicated. PMID:27625575

  7. Bacterial persistence induced by salicylate via reactive oxygen species

    PubMed Central

    Wang, Tiebin; El Meouche, Imane; Dunlop, Mary J.

    2017-01-01

    Persisters are phenotypic variants of regular cells that exist in a dormant state with low metabolic activity, allowing them to exhibit high tolerance to antibiotics. Despite increasing recognition of their role in chronic and recalcitrant infections, the mechanisms that induce persister formation are not fully understood. In this study, we find that salicylate can induce persister formation in Escherichia coli via generation of reactive oxygen species (ROS). Salicylate-induced ROS cause a decrease in the membrane potential, reduce metabolism and lead to an increase in persistence. These effects can be recovered by culturing cells in the presence of a ROS quencher or in an anaerobic environment. Our findings reveal that salicylate-induced oxidative stress can lead to persistence, suggesting that ROS, and their subsequent impact on membrane potential and metabolism, may play a broad role in persister formation. PMID:28281556

  8. Reactive oxygen species, essential molecules, during plant-pathogen interactions.

    PubMed

    Camejo, Daymi; Guzmán-Cedeño, Ángel; Moreno, Alexander

    2016-06-01

    Reactive oxygen species (ROS) are continually generated as a consequence of the normal metabolism in aerobic organisms. Accumulation and release of ROS into cell take place in response to a wide variety of adverse environmental conditions including salt, temperature, cold stresses and pathogen attack, among others. In plants, peroxidases class III, NADPH oxidase (NOX) locates in cell wall and plasma membrane, respectively, may be mainly enzymatic systems involving ROS generation. It is well documented that ROS play a dual role into cells, acting as important signal transduction molecules and as toxic molecules with strong oxidant power, however some aspects related to its function during plant-pathogen interactions remain unclear. This review focuses on the principal enzymatic systems involving ROS generation addressing the role of ROS as signal molecules during plant-pathogen interactions. We described how the chloroplasts, mitochondria and peroxisomes perceive the external stimuli as pathogen invasion, and trigger resistance response using ROS as signal molecule.

  9. In vitro degradation of tropoelastin by reactive oxygen species.

    PubMed

    Hayashi, A; Ryu, A; Suzuki, T; Kawada, A; Tajima, S

    1998-09-01

    The effects of reactive oxygen species (ROS) on elastin molecules (tropoelastin) were studied in vitro. ROS generated by ultraviolet A and hematoporphyrin rapidly degraded tropoelastin within 5 min. Their degradative activity was inhibited by the addition of NaN3. Treatment of tropoelastin with copper sulfate/ascorbic acid resulted in degradation of tropoelastin producing fragments of molecular weight 45, 30 and 10 kDa within 30 min. The degradation of tropoelastin was partially blocked by the addition of mannitol. ROS induced by the xanthine/xanthine oxidase system also degraded tropoelastin within 6 h. The degradation was blocked by catalase but not by superoxide dismutase (SOD). ROS generated by copper-ascorbate seems to be unique in that it cleaves relatively specific sites of the tropoelastin molecule. Thus ROS may play a degradative role in elastin metabolism which may cause the elastolytic changes or the deposition of fragmented elastic fibers in photoaged skin or age-related elastolytic disorders.

  10. Diabetic peripheral neuropathy: role of reactive oxygen and nitrogen species.

    PubMed

    Premkumar, Louis S; Pabbidi, Reddy M

    2013-11-01

    The prevalence of diabetes has reached epidemic proportions. There are two forms of diabetes: type 1 diabetes mellitus is due to auto-immune-mediated destruction of pancreatic β-cells resulting in absolute insulin deficiency and type 2 diabetes mellitus is due to reduced insulin secretion and or insulin resistance. Both forms of diabetes are characterized by chronic hyperglycemia, leading to the development of diabetic peripheral neuropathy (DPN) and microvascular pathology. DPN is characterized by enhanced or reduced thermal, chemical, and mechanical pain sensitivities. In the long-term, DPN results in peripheral nerve damage and accounts for a substantial number of non-traumatic lower-limb amputations. This review will address the mechanisms, especially the role of reactive oxygen and nitrogen species in the development and progression of DPN.

  11. Reactive oxygen species-targeted therapeutic interventions for atrial fibrillation

    PubMed Central

    Sovari, Ali A.; Dudley, Samuel C.

    2012-01-01

    Atrial fibrillation (AF) is the most common arrhythmia that requires medical attention, and its incidence is increasing. Current ion channel blockade therapies and catheter ablation have significant limitations in treatment of AF, mainly because they do not address the underlying pathophysiology of the disease. Oxidative stress has been implicated as a major underlying pathology that promotes AF; however, conventional antioxidants have not shown impressive therapeutic effects. A more careful design of antioxidant therapies and better selection of patients likely are required to treat effectively AF with antioxidant agents. Current evidence suggest inhibition of prominent cardiac sources of reactive oxygen species (ROS) such as nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and targeting subcellular compartments with the highest levels of ROS may prove to be effective therapies for AF. Increased serum markers of oxidative stress may be an important guide in selecting the AF patients who will most likely respond to antioxidant therapy. PMID:22934062

  12. NADPH oxidase-derived reactive oxygen species in cardiac pathophysiology

    PubMed Central

    Cave, Alison; Grieve, David; Johar, Sofian; Zhang, Min; Shah, Ajay M

    2005-01-01

    Chronic heart failure, secondary to left ventricular hypertrophy or myocardial infarction, is a condition with increasing morbidity and mortality. Although the mechanisms underlying the development and progression of this condition remain a subject of intense interest, there is now growing evidence that redox-sensitive pathways play an important role. This article focuses on the involvement of reactive oxygen species derived from a family of superoxide-generating enzymes, termed NADPH oxidases (NOXs), in the pathophysiology of ventricular hypertrophy, the accompanying interstitial fibrosis and subsequent heart failure. In particular, the apparent ability of the different NADPH oxidase isoforms to define the response of a cell to a range of physiological and pathophysiological stimuli is reviewed. If confirmed, these data would suggest that independently targeting different members of the NOX family may hold the potential for therapeutic intervention in the treatment of cardiac disease. PMID:16321803

  13. How reactive oxygen species and proline face stress together.

    PubMed

    Ben Rejeb, Kilani; Abdelly, Chedly; Savouré, Arnould

    2014-07-01

    Reactive oxygen species (ROS) are continuously generated as a consequence of plant metabolic processes due to incomplete reduction of O2. Previously considered to be only toxic by-products of metabolism, ROS are now known to act as second messengers in intracellular signalling cascades to trigger tolerance of various abiotic and biotic stresses. The accumulation of proline is frequently observed during the exposure of plants to adverse environmental conditions. Interestingly proline metabolism may also contribute to ROS formation in mitochondria, which play notably a role in hypersensitive response in plants, life-span extension in worms and tumor suppression in animals. Here we review current knowledge about the regulation of proline metabolism in response to environmental constraints and highlight the key role of ROS in the regulation of this metabolism. The impact of proline on ROS generation is also investigated. Deciphering and integrating these relationships at the whole plant level will bring new perspectives on how plants adapt to environmental stresses.

  14. Reactive nitrogen species scavenging, rather than nitric oxide inhibition, protects from articular cartilage damage in rat zymosan-induced arthritis

    PubMed Central

    Bezerra, Mirna Marques; Brain, Susan D; Greenacre, Stan; Jerônimo, Selma Maria Bezerra; de Melo, Liana Batista; Keeble, Julie; da Rocha, Francisco Airton Castro

    2003-01-01

    The contribution of nitric oxide (NO) and peroxynitrite (PN) to inflammation in a zymosan-induced (1 mg, intra-articular, i.art.) rat model of arthritis was assessed by histopathology and by measuring the glycosaminoglycan (GAG) content of the articular cartilage. Progression of the chronic synovitis in zymosan-induced arthritis (ZYA) was associated with increased nitrite and nitrotyrosine (3-NT) levels in the joint exudates that paralleled a progressive loss of the GAG content. An increase in 3-NT was also observed after i.art. PN. The nonselective nitric oxide synthase (NOS) inhibitor L-NG-nitroarginine methyl ester (25–75 mg kg−1day−1) or the selective inducible NOS inhibitor aminoguanidine (50–100 mg kg−1day−1) given 1 h before (prophylactic) or 3 days after (therapeutic) injection of the zymosan ameliorated the synovitis, but worsened the GAG loss, as measured at the end of the experiment (day 7). The PN scavenger uric acid (100–250 mg kg−1 i.p. four times daily) given prophylactically until the end of the experiment (day 14), in a dose compatible with its PN scavenging activity, significantly decreased both the synovitis and the GAG loss. In conclusion, PN formation is associated with cartilage damage in addition to proinflammatory activity in ZYA. NOS inhibitors and a PN scavenger were able to reduce the cellular infiltration, while displaying opposite effects on cartilage homeostasis either by enhancing or ameliorating the damage, respectively. PMID:14662723

  15. Gamma-irradiation produces active chlorine species (ACS) in physiological solutions: Secoisolariciresinol diglucoside (SDG) scavenges ACS - A novel mechanism of DNA radioprotection

    PubMed Central

    Mishra, Om P.; Popov, Anatoliy V.; Pietrofesa, Ralph A.; Christofidou-Solomidou, Melpo

    2017-01-01

    Background Secoisolariciresinol diglucoside (SDG), the main lignan in whole grain flaxseed, is a potent antioxidant and free radical scavenger with known radioprotective properties. However, the exact mechanism of SDG radioprotection is not well understood. The current study identified a novel mechanism of DNA radioprotection by SDG in physiological solutions by scavenging active chlorine species (ACS) and reducing chlorinated nucleobases. Methods The ACS scavenging activity of SDG was determined using two highly specific fluoroprobes: hypochlorite-specific 3′-(p-aminophenyl) fluorescein (APF) and hydroxyl radical-sensitive 3′-(p-hydroxyphenyl) fluorescein (HPF). Dopamine, an SDG structural analog, was used for proton 1H NMR studies to trap primary ACS radicals. Taurine N-chlorination was determined to demonstrate radiation-induced generation of hypochlorite, a secondary ACS. DNA protection was assessed by determining the extent of DNA fragmentation and plasmid DNA relaxation following exposure to ClO− and radiation. Purine base chlorination by ClO− and γ-radiation was determined by using 2-aminopurine (2-AP), a fluorescent analog of 6-aminopurine. Results: Chloride anions (Cl−) consumed >90% of hydroxyl radicals in physiological solutions produced by γ-radiation resulting in ACS formation, which was detected by 1H NMR. Importantly, SDG scavenged hypochlorite- and γ-radiation-induced ACS. In addition, SDG blunted ACS-induced fragmentation of calf thymus DNA and plasmid DNA relaxation. SDG treatment before or after ACS exposure decreased the ClO− or γ-radiation-induced chlorination of 2-AP. Exposure to γ-radiation resulted in increased taurine chlorination, indicative of ClO− generation. NMR studies revealed formation of primary ACS radicals (chlorine atoms (Cl•) and dichloro radical anions (Cl2−•)), which were trapped by SDG and its structural analog dopamine. Conclusion We demonstrate that γ-radiation induces the generation of ACS in

  16. Release of proteins from intact chloroplasts induced by reactive oxygen species during biotic and abiotic stress.

    PubMed

    Kwon, Kwang-Chul; Verma, Dheeraj; Jin, Shuangxia; Singh, Nameirakpam D; Daniell, Henry

    2013-01-01

    Plastids sustain life on this planet by providing food, feed, essential biomolecules and oxygen. Such diverse metabolic and biosynthetic functions require efficient communication between plastids and the nucleus. However, specific factors, especially large molecules, released from plastids that regulate nuclear genes have not yet been fully elucidated. When tobacco and lettuce transplastomic plants expressing GFP within chloroplasts, were challenged with Erwinia carotovora (biotic stress) or paraquat (abiotic stress), GFP was released into the cytoplasm. During this process GFP moves gradually towards the envelope, creating a central red zone of chlorophyll fluorescence. GFP was then gradually released from intact chloroplasts into the cytoplasm with an intact vacuole and no other visible cellular damage. Different stages of GFP release were observed inside the same cell with a few chloroplasts completely releasing GFP with detection of only red chlorophyll fluorescence or with no reduction in GFP fluorescence or transitional steps between these two phases. Time lapse imaging by confocal microscopy clearly identified sequence of these events. Intactness of chloroplasts during this process was evident from chlorophyll fluorescence emanated from thylakoid membranes and in vivo Chla fluorescence measurements (maximum quantum yield of photosystem II) made before or after infection with pathogens to evaluate their photosynthetic competence. Hydrogen peroxide and superoxide anion serve as signal molecules for generation of reactive oxygen species and Tiron, scavenger of superoxide anion, blocked release of GFP from chloroplasts. Significant increase in ion leakage in the presence of paraquat and light suggests changes in the chloroplast envelope to facilitate protein release. Release of GFP-RC101 (an antimicrobial peptide), which was triggered by Erwinia infection, ceased after conferring protection, further confirming this export phenomenon. These results suggest a

  17. Generation of Reactive Oxygen Species Contributes to the Development of Carbon Black Cytotoxicity to Vascular Cells

    PubMed Central

    Lee, Jong Gwan; Noh, Won Jun; Kim, Hwa

    2011-01-01

    Carbon black, a particulate form of pure elemental carbon, is an industrial chemical with the high potential of occupational exposure. Although the relationship between exposure to particulate matters (PM) and cardiovascular diseases is well established, the cardiovascular risk of carbon black has not been characterized clearly. In this study, the cytotoxicity of carbon black to vascular smooth muscle and endothelial cells were examined to investigate the potential vascular toxicity of carbon black. Carbon black with distinct particle size, N330 (primary size, 28~36 nm) and N990 (250~350 nm) were treated to A-10, rat aortic smooth muscle cells and human umbilical vein endothelial cell line, ECV304, and cell viability was assessed by lactate dehydrogenase (LDH) leakage assay. Treatment of carbon black N990 resulted in the significant reduction of viability in A-10 cells at 100 μg/ml, the highest concentration tested, while N330 failed to cause cell death. Cytotoxicity to ECV304 cells was induced only by N330 at higher concentration, 200 μg/ml, suggesting that ECV304 cells were relatively resistant to carbon black. Treatment of 100 μg/ml N990 led to the elevation of reactive oxygen species (ROS) detected by dichlorodihydrofluorescein (DCF) in A-10 cells. Pretreatment of antioxidants, N-acetylcysteine (NAC) and sulforaphane restored decreased viability of N990-treated A-10 cells, and N-acetylcysteine, but not sulforaphane, attenuated N990-induced ROS generation in A-10 cells. Taken together, present study shows that carbon black is cytotoxic to vascular cells, and the generation of reactive oxygen contributes to the development of cytotoxicity. ROS scavenging antioxidant could be a potential strategy to attenuate the toxicity induced by carbon black exposure. PMID:24278567

  18. Interconnection of reactive oxygen species chemistry across the interfaces of atmospheric, environmental, and biological processes.

    PubMed

    Anglada, Josep M; Martins-Costa, Marilia; Francisco, Joseph S; Ruiz-López, Manuel F

    2015-03-17

    Oxidation reactions are ubiquitous and play key roles in the chemistry of the atmosphere, in water treatment processes, and in aerobic organisms. Ozone (O3), hydrogen peroxide (H2O2), hydrogen polyoxides (H2Ox, x > 2), associated hydroxyl and hydroperoxyl radicals (HOx = OH and HO2), and superoxide and ozonide anions (O2(-) and O3(-), respectively) are the primary oxidants in these systems. They are commonly classified as reactive oxygen species (ROS). Atmospheric chemistry is driven by a complex system of chain reactions of species, including nitrogen oxides, hydroxyl and hydroperoxide radicals, alkoxy and peroxy radicals, and ozone. HOx radicals contribute to keeping air clean, but in polluted areas, the ozone concentration increases and creates a negative impact on plants and animals. Indeed, ozone concentration is used to assess air quality worldwide. Clouds have a direct effect on the chemical composition of the atmosphere. On one hand, cloud droplets absorb many trace atmospheric gases, which can be scavenged by rain and fog. On the other hand, ionic species can form in this medium, which makes the chemistry of the atmosphere richer and more complex. Furthermore, recent studies have suggested that air-cloud interfaces might have a significant impact on the overall chemistry of the troposphere. Despite the large differences in molecular composition, concentration, and thermodynamic conditions among atmospheric, environmental, and biological systems, the underlying chemistry involving ROS has many similarities. In this Account, we examine ROS and discuss the chemical characteristics common to all of these systems. In water treatment, ROS are key components of an important subset of advanced oxidation processes. Ozonation, peroxone chemistry, and Fenton reactions play important roles in generating sufficient amounts of hydroxyl radicals to purify wastewater. Biochemical processes within living organisms also involve ROS. These species can come from pollutants in

  19. Hydrogen scavengers

    DOEpatents

    Carroll, David W.; Salazar, Kenneth V.; Trkula, Mitchell; Sandoval, Cynthia W.

    2002-01-01

    There has been invented a codeposition process for fabricating hydrogen scavengers. First, a .pi.-bonded allylic organometallic complex is prepared by reacting an allylic transition metal halide with an organic ligand complexed with an alkali metal; and then, in a second step, a vapor of the .pi.-bonded allylic organometallic complex is combined with the vapor of an acetylenic compound, irradiated with UV light, and codeposited on a substrate.

  20. Radical Oxygen Species, Exercise and Aging: An Update.

    PubMed

    Bouzid, Mohamed Amine; Filaire, Edith; McCall, Alan; Fabre, Claudine

    2015-09-01

    It is now well established that reactive oxygen species (ROS) play a dual role as both deleterious and beneficial species. In fact, ROS act as secondary messengers in intracellular signalling cascades; however, they can also induce cellular senescence and apoptosis. Aging is an intricate phenomenon characterized by a progressive decline in physiological functions and an increase in mortality, which is often accompanied by many pathological diseases. ROS are involved in age-associated damage to macromolecules, and this may cause derangement in ROS-mediated cell signalling, resulting in stress and diseases. Moreover, the role of oxidative stress in age-related sarcopenia provides strong evidence for the important contribution of physical activity to limit this process. Regular physical activity is considered a preventive measure against oxidative stress-related diseases. The aim of this review is to summarize the currently available studies investigating the effects of chronic and/or acute physical exercise on the oxidative stress process in healthy elderly subjects. Although studies on oxidative stress and physical activity are limited, the available information shows that acute exercise increases ROS production and oxidative stress damage in older adults, whereas chronic exercise could protect elderly subjects from oxidative stress damage and reinforce their antioxidant defences. The available studies reveal that to promote beneficial effects of physical activity on oxidative stress, elderly subjects require moderate-intensity training rather than high-intensity exercise.

  1. Role of reactive oxygen species in fungal cellular differentiations.

    PubMed

    Scott, Barry; Eaton, Carla J

    2008-12-01

    Regulated synthesis of reactive oxygen species (ROS) by specific fungal NADPH oxidases (Noxs) plays a key role in fungal cellular differentiation and development. Fungi have up to three different Nox isoforms, NoxA, B and C. The NoxA isoform has a key role in triggering the development of fruiting bodies in several sexual species whereas NoxB plays a key role in ascospore germination. The function of NoxC remains unknown. Both NoxA and NoxB are required for the development of fungal infection structures by some plant pathogens. ROS production by NoxA is critical for maintaining a fungal-plant symbiosis. Localised synthesis of ROS is also important in establishing and maintaining polarised hyphal growth. Activation of NoxA/NoxB requires the regulatory subunit, NoxR, and the small GTPase RacA. The BemA scaffold protein may also be involved in the assembly of the Nox complex. By analogy with mammalian systems MAP and PAK kinases may regulate fungal Nox activation. How fungal cells sense and respond to ROS associated with cellular differentiations remains to be discovered.

  2. Cell signaling by reactive nitrogen and oxygen species in atherosclerosis

    NASA Technical Reports Server (NTRS)

    Patel, R. P.; Moellering, D.; Murphy-Ullrich, J.; Jo, H.; Beckman, J. S.; Darley-Usmar, V. M.

    2000-01-01

    The production of reactive oxygen and nitrogen species has been implicated in atherosclerosis principally as means of damaging low-density lipoprotein that in turn initiates the accumulation of cholesterol in macrophages. The diversity of novel oxidative modifications to lipids and proteins recently identified in atherosclerotic lesions has revealed surprising complexity in the mechanisms of oxidative damage and their potential role in atherosclerosis. Oxidative or nitrosative stress does not completely consume intracellular antioxidants leading to cell death as previously thought. Rather, oxidative and nitrosative stress have a more subtle impact on the atherogenic process by modulating intracellular signaling pathways in vascular tissues to affect inflammatory cell adhesion, migration, proliferation, and differentiation. Furthermore, cellular responses can affect the production of nitric oxide, which in turn can strongly influence the nature of oxidative modifications occurring in atherosclerosis. The dynamic interactions between endogenous low concentrations of oxidants or reactive nitrogen species with intracellular signaling pathways may have a general role in processes affecting wound healing to apoptosis, which can provide novel insights into the pathogenesis of atherosclerosis.

  3. [Generation of reactive oxygen species in water under exposure of visible or infrared irradiation at absorption band of molecular oxygen].

    PubMed

    Gudkov, S V; Karp, O E; Garmash, S A; Ivanov, V E; Chernikov, A V; Manokhin, A A; Astashev, M E; Iaguzhinskiĭ, L S; Bruskov, V I

    2012-01-01

    It is found that in bidistilled water saturated with oxygen hydrogen peroxide and hydroxyl radicals are formed under the influence of visible and infrared radiation in the absorption bands of molecular oxygen. Formation of reactive oxygen species (ROS) occurs under the influence of both solar and artificial light sourses, including the coherent laser irradiation. The oxygen effect, i.e. the impact of dissolved oxygen concentration on production of hydrogen peroxide induced by light, is detected. It is shown that the visible and infrared radiation in the absorption bands of molecular oxygen leads to the formation of 8-oxoguanine in DNA in vitro. Physicochemical mechanisms of ROS formation in water when exposed to visible and infrared light are studied, and the involvement of singlet oxygen and superoxide anion radicals in this process is shown.

  4. Aloe-emodin induced DNA damage through generation of reactive oxygen species in human lung carcinoma cells.

    PubMed

    Lee, Hong-Zin; Lin, Ching-Ju; Yang, Wen-Hui; Leung, Wing-Cheung; Chang, Shen-Pen

    2006-07-28

    The DNA aggregation was found in aloe-emodin-induced H460 cell apoptosis in this study. Aloe-emodin (40microM)-induced DNA single strand breaks were observed by comet assay. Aloe-emodin induced decreases in the mRNA of DNA repair enzymes such as hMTH1, hOGG1 and APE. Although the activity of the radical-scavenging enzyme SOD was enhanced by aloe-emodin, the effects of aloe-emodin on H460 cell apoptosis were suspected to result from the prooxidant. These results suggest that aloe-emodin induced DNA damage through generation of reactive oxygen species in human lung carcinoma cells.

  5. Non-thermal dielectric barrier discharge plasma induces angiogenesis through reactive oxygen species

    PubMed Central

    Arjunan, Krishna Priya; Friedman, Gary; Fridman, Alexander; Clyne, Alisa Morss

    2012-01-01

    Vascularization plays a key role in processes such as wound healing and tissue engineering. Non-thermal plasma, which primarily produces reactive oxygen species (ROS), has recently emerged as an efficient tool in medical applications including blood coagulation, sterilization and malignant cell apoptosis. Liquids and porcine aortic endothelial cells were treated with a non-thermal dielectric barrier discharge plasma in vitro. Plasma treatment of phosphate-buffered saline (PBS) and serum-free medium increased ROS concentration in a dose-dependent manner, with a higher concentration observed in serum-free medium compared with PBS. Species concentration inside cells peaked 1 h after treatment, followed by a decrease 3 h post treatment. Endothelial cells treated with a plasma dose of 4.2 J cm–2 had 1.7 times more cells than untreated samples 5 days after plasma treatment. The 4.2 J cm–2 plasma dose increased two-dimensional migration distance by 40 per cent compared with untreated control, while the number of cells that migrated through a three-dimensional collagen gel increased by 15 per cent. Tube formation was also enhanced by plasma treatment, with tube lengths in plasma-treated samples measuring 2.6 times longer than control samples. A fibroblast growth factor-2 (FGF-2) neutralizing antibody and ROS scavengers abrogated these angiogenic effects. These data indicate that plasma enhanced proliferation, migration and tube formation is due to FGF-2 release induced by plasma-produced ROS. Non-thermal plasma may be used as a potential tool for applying ROS in precise doses to enhance vascularization. PMID:21653568

  6. Enzymatic Production of Extracellular Reactive Oxygen Species by Marine Microorganisms

    NASA Astrophysics Data System (ADS)

    Diaz, J. M.; Andeer, P. F.; Hansel, C. M.

    2014-12-01

    Reactive oxygen species (ROS) serve as intermediates in a myriad of biogeochemically important processes, including cell signaling pathways, cellular oxidative stress responses, and the transformation of both nutrient and toxic metals such as iron and mercury. Abiotic reactions involving the photo-oxidation of organic matter were once considered the only important sources of ROS in the environment. However, the recent discovery of substantial biological ROS production in marine systems has fundamentally shifted this paradigm. Within the last few decades, marine phytoplankton, including diatoms of the genus Thalassiosira, were discovered to produce ample extracellular quantities of the ROS superoxide. Even more recently, we discovered widespread production of extracellular superoxide by phylogenetically and ecologically diverse heterotrophic bacteria at environmentally significant levels (up to 20 amol cell-1 hr-1), which has introduced the revolutionary potential for substantial "dark" cycling of ROS. Despite the profound biogeochemical importance of extracellular biogenic ROS, the cellular mechanisms underlying the production of this ROS have remained elusive. Through the development of a gel-based assay to identify extracellular ROS-producing proteins, we have recently found that enzymes typically involved in antioxidant activity also produce superoxide when molecular oxygen is the only available electron acceptor. For example, large (~3600 amino acids) heme peroxidases are involved in extracellular superoxide production by a bacterium within the widespread Roseobacter clade. In Thalassiosira spp., extracellular superoxide is produced by flavoproteins such as glutathione reductase and ferredoxin NADP+ reductase. Thus, extracellular ROS production may occur via secreted and/or cell surface enzymes that modulate between producing and degrading ROS depending on prevailing geochemical and/or ecological conditions.

  7. Understanding how mammalian scavengers use information from avian scavengers: cue from above.

    PubMed

    Kane, Adam; Kendall, Corinne J

    2017-03-15

    Interspecific social information transfer can play a key role in many aspects of animal ecology from foraging to habitat selection to predator avoidance. Within scavenging communities, avian scavengers often act as producers and mammalian scavengers act as scroungers, but we predict that species-specific cueing will allow for mammalian scavengers to utilize particular avian scavenger species using preferred food sources similar to their own preferences. We use empirical and theoretic approaches to assess interactions between mammalian and avian scavengers in one of the most diverse scavenging guilds in Masai Mara National Reserve, Kenya. Using a spatially explicit model and data from experimental carcasses, we found evidence that mammals benefit from local enhancement provided by vultures and that mammalian-avian following patterns are consistent with the idea that species-specific cueing is occurring. Results suggest that ongoing population declines in avian scavengers may have significant impacts on mammalian scavengers and potentially create trophic cascades.

  8. Therapeutic Strategies for Oxidative Stress-Related Cardiovascular Diseases: Removal of Excess Reactive Oxygen Species in Adult Stem Cells.

    PubMed

    Kim, Hyunyun; Yun, Jisoo; Kwon, Sang-Mo

    Accumulating evidence indicates that acute and chronic uncontrolled overproduction of oxidative stress-related factors including reactive oxygen species (ROS) causes cardiovascular diseases (CVDs), atherosclerosis, and diabetes. Moreover ROS mediate various signaling pathways underlying vascular inflammation in ischemic tissues. With respect to stem cell-based therapy, several studies clearly indicate that modulating antioxidant production at cellular levels enhances stem/progenitor cell functionalities, including proliferation, long-term survival in ischemic tissues, and complete differentiation of transplanted cells into mature vascular cells. Recently emerging therapeutic strategies involving adult stem cells, including endothelial progenitor cells (EPCs), for treating ischemic CVDs have highlighted the need to control intracellular ROS production, because it critically affects the replicative senescence of ex vivo expanded therapeutic cells. Better understanding of the complexity of cellular ROS in stem cell biology might improve cell survival in ischemic tissues and enhance the regenerative potentials of transplanted stem/progenitor cells. In this review, we will discuss the nature and sources of ROS, drug-based therapeutic strategies for scavenging ROS, and EPC based therapeutic strategies for treating oxidative stress-related CVDs. Furthermore, we will discuss whether primed EPCs pretreated with natural ROS-scavenging compounds are crucial and promising therapeutic strategies for vascular repair.

  9. Flaxseed oil increases aortic reactivity to phenylephrine through reactive oxygen species and the cyclooxygenase-2 pathway in rats

    PubMed Central

    2014-01-01

    Background Flaxseed oil has the highest concentration of omega-3 α-linolenic acid, which has been associated with cardiovascular benefit. However, the mechanism underlying the vascular effects induced through flaxseed oil is not well known. Thus, in the present study, we investigated the effects of flaxseed oil on vascular function in isolated rat aortic rings. Methods Wistar rats were treated daily with flaxseed oil or a control (mineral oil) intramuscular (i.m.) for fifteen days. Isolated aortic segments were used to evaluate cyclooxygenase-2 (COX-2) protein expression, superoxide anion levels and vascular reactivity experiments. Results Flaxseed oil treatment increased the vasoconstrictor response of aortic rings to phenylephrine. Endothelium removal increased the response to phenylephrine in aortic segments isolated from both groups, but the effect was smaller in the treated group. L-NAME incubation similarly increased the phenylephrine response in segments from both groups. The TXA2 synthase inhibitor furegrelate, the selective COX-2 inhibitor NS 398, the TP receptor antagonist SQ 29.548, the reactive oxygen species (ROS) scavenger apocynin, the superoxide anion scavengers tiron and the phospholipase A2 inhibitor dexamethasone partially reversed the flaxseed oil-induced increase in reactivity to phenylephrine. Conclusions These findings suggest that flaxseed oil treatment increased vascular reactivity to phenylephrine through an increase in ROS production and COX-2-derived TXA2 production. The results obtained in the present study provide new insight into the effects of flaxseed oil treatment (i.m.) on vascular function. PMID:24993607

  10. Therapeutic Strategies for Oxidative Stress-Related Cardiovascular Diseases: Removal of Excess Reactive Oxygen Species in Adult Stem Cells

    PubMed Central

    Yun, Jisoo

    2016-01-01

    Accumulating evidence indicates that acute and chronic uncontrolled overproduction of oxidative stress-related factors including reactive oxygen species (ROS) causes cardiovascular diseases (CVDs), atherosclerosis, and diabetes. Moreover ROS mediate various signaling pathways underlying vascular inflammation in ischemic tissues. With respect to stem cell-based therapy, several studies clearly indicate that modulating antioxidant production at cellular levels enhances stem/progenitor cell functionalities, including proliferation, long-term survival in ischemic tissues, and complete differentiation of transplanted cells into mature vascular cells. Recently emerging therapeutic strategies involving adult stem cells, including endothelial progenitor cells (EPCs), for treating ischemic CVDs have highlighted the need to control intracellular ROS production, because it critically affects the replicative senescence of ex vivo expanded therapeutic cells. Better understanding of the complexity of cellular ROS in stem cell biology might improve cell survival in ischemic tissues and enhance the regenerative potentials of transplanted stem/progenitor cells. In this review, we will discuss the nature and sources of ROS, drug-based therapeutic strategies for scavenging ROS, and EPC based therapeutic strategies for treating oxidative stress-related CVDs. Furthermore, we will discuss whether primed EPCs pretreated with natural ROS-scavenging compounds are crucial and promising therapeutic strategies for vascular repair. PMID:27668035

  11. DNA breakage induced by 1,2,4-benzenetriol: relative contributions of oxygen-derived active species and transition metal ions.

    PubMed

    Li, A S; Bandy, B; Tsang, S; Davison, A J

    2001-05-01

    We report here the relative roles of metals and selected reactive oxygen species in DNA damage by the genotoxic benzene metabolite 1,2,4-benzenetriol, and the interactions of antioxidants in affording protection. 1,2,4-Benzenetriol induces scission in supercoiled phage DNA in neutral aqueous solution with an effective dose (ED(50)) of 6.7 microM for 50% cleavage of 2.05 microg/ml supercoiled PM2 DNA. In decreasing order of effectiveness: catalase (20 U/ml), formate (25 mM), superoxide dismutase (20 U/ml), and mannitol (50 mM) protected, from 85 to 28%. Evidently, H(2)O(2) is the dominant active species, with O(2)(*)(-) and *OH playing subordinate roles. Desferrioxamine or EDTA inhibited DNA breakage by 81-85%, despite accelerating 1,2,4-benzenetriol autoxidation. Consistent with this suggestion of a crucial role for metals, addition of cupric, cuprous, ferric, or ferrous ions enhanced DNA breakage, with copper being more active than iron. Combinations of scavengers protected more effectively than any single scavenger alone, with implications for antioxidants acting in concert in living cells. Synergistic combinations were superoxide dismutase with *OH scavengers, superoxide dismutase with desferrioxamine, and catalase with desferrioxamine. Antagonistic (preemptive) combinations were catalase with superoxide dismutase, desferrioxamine with *OH scavengers, and catalase with *OH scavengers. The most striking aspect of synergism was the extent to which metal chelation (desferrioxamine) acted synergistically with either catalase or superoxide dismutase to provide virtually complete protection. Concluding, 1,2,4-benzenetriol-induced DNA damage occurs mainly by site-specific, Fenton-type mechanisms, involving synergism between several reactive intermediates. Multiple antioxidant actions are needed for effective protection.

  12. Molecular and biochemical mechanisms in teratogenesis involving reactive oxygen species.

    PubMed

    Wells, Peter G; Bhuller, Yadvinder; Chen, Connie S; Jeng, Winnie; Kasapinovic, Sonja; Kennedy, Julia C; Kim, Perry M; Laposa, Rebecca R; McCallum, Gordon P; Nicol, Christopher J; Parman, Toufan; Wiley, Michael J; Wong, Andrea W

    2005-09-01

    Developmental pathologies may result from endogenous or xenobiotic-enhanced formation of reactive oxygen species (ROS), which oxidatively damage cellular macromolecules and/or alter signal transduction. This minireview focuses upon several model drugs (phenytoin, thalidomide, methamphetamine), environmental chemicals (benzo[a]pyrene) and gamma irradiation to examine this hypothesis in vivo and in embryo culture using mouse, rat and rabbit models. Embryonic prostaglandin H synthases (PHSs) and lipoxygenases bioactivate xenobiotics to free radical intermediates that initiate ROS formation, resulting in oxidation of proteins, lipids and DNA. Oxidative DNA damage and embryopathies are reduced in PHS knockout mice, and in mice treated with PHS inhibitors, antioxidative enzymes, antioxidants and free radical trapping agents. Thalidomide causes embryonic DNA oxidation in susceptible (rabbit) but not resistant (mouse) species. Embryopathies are increased in mutant mice deficient in the antioxidative enzyme glucose-6-phosphate dehydrogenase (G6PD), or by glutathione (GSH) depletion, or inhibition of GSH peroxidase or GSH reductase. Inducible nitric oxide synthase knockout mice are partially protected. Inhibition of Ras or NF-kB pathways reduces embryopathies, implicating ROS-mediated signal transduction. Atm and p53 knockout mice deficient in DNA damage response/repair are more susceptible to xenobiotic or radiation embryopathies, suggesting a teratological role for DNA damage, consistent with enhanced susceptibility to methamphetamine in ogg1 knockout mice with deficient repair of oxidative DNA damage. Even endogenous embryonic oxidative stress carries a risk, since untreated G6PD- or ATM-deficient mice have increased embryopathies. Thus, embryonic processes regulating the balance of ROS formation, oxidative DNA damage and repair, and ROS-mediated signal transduction may be important determinants of teratological risk.

  13. Oxygen free-radical scavengers and immune destruction of murine islets in allograft rejection and multiple low-dose streptozocin-induced insulitis.

    PubMed

    Mendola, J; Wright, J R; Lacy, P E

    1989-03-01

    We examined the effects of desferrioxamine (DFX), a potent inhibitor of the formation of oxygen-derived hydroxyl radicals, and nicotinamide (NIC), a poly(ADP-ribose) synthetase inhibitor and a weak free-radical scavenger, on two models of immune destruction of murine islets [i.e., allograft rejection and multiple low-dose streptozocin (STZ)-induced insulitis]. Freshly isolated or low-temperature-cultured BALB/cJ islets were transplanted beneath the kidney capsules of C57BL/6J recipients. The recipients were treated with NIC alone (500 mg.kg-1.day-1), DFX alone (4.2 mg/day x 14 days), or NIC + DFX. Only recipients treated with NIC + DFX, receiving cultured islets, showed a mean graft survival time significantly longer than control mice receiving freshly isolated or cultured islets. Control CD-1 mice treated with multiple low doses of STZ developed insulitis and diabetes. Treatment with NIC alone, DFX alone, or NIC + DFX decreased the severity of hyperglycemia relative to the controls. Treatment with DFX alone was more effective than NIC alone or NIC + DFX. Only the group treated with DFX alone had a lower incidence of diabetes (mean plasma glucose level greater than 200 mg/dl) than the controls after 4 wk. Histologically, islets from control mice showed severe insulitis, islet destruction, and absence of stainable insulin, whereas islets from DFX-treated mice showed only mild peri-insulitis and a relative preservation of beta-cell granulation. Our study showed that NIC and DFX partially protect islets from immune destruction in allograft rejection and in low-dose STZ-induced insulitis. Apparently, hydroxyl radicals play important roles in both of these models.

  14. Reactive oxygen species at the crossroads of inflammasome and inflammation

    PubMed Central

    Harijith, Anantha; Ebenezer, David L.; Natarajan, Viswanathan

    2014-01-01

    Inflammasomes form a crucial part of the innate immune system. These are multi-protein oligomer platforms that are composed of intracellular sensors which are coupled with caspase and interleukin activating systems. Nod-like receptor protein (NLRP) 3, and 6 and NLRC4 and AIM2 are the prominent members of the inflammasome family. Inflammasome activation leads to pyroptosis, a process of programmed cell death distinct from apoptosis through activation of Caspase and further downstream targets such as IL-1β and IL-18 leading to activation of inflammatory cascade. Reactive oxygen species (ROS) serves as important inflammasome activating signals. ROS activates inflammasome through mitogen-activated protein kinases (MAPK) and extracellular signal-regulated protein kinases 1 and 2 (ERK1/2). Dysregulation of inflammasome plays a significant role in various pathological processes. Viral infections such as Dengue and Respiratory syncytial virus activate inflammasomes. Crystal compounds in silicosis and gout also activate ROS. In diabetes, inhibition of autophagy with resultant accumulation of dysfunctional mitochondria leads to enhanced ROS production activating inflammasomes. Activation of inflammasomes can be dampened by antioxidants such as SIRT-1. Inflammasome and related cascade could serve as future therapeutic targets for various pathological conditions. PMID:25324778

  15. Reactive Oxygen Species (ROS): Beneficial Companions of Plants’ Developmental Processes

    PubMed Central

    Singh, Rachana; Singh, Samiksha; Parihar, Parul; Mishra, Rohit K.; Tripathi, Durgesh K.; Singh, Vijay P.; Chauhan, Devendra K.; Prasad, Sheo M.

    2016-01-01

    Reactive oxygen species (ROS) are generated inevitably in the redox reactions of plants, including respiration and photosynthesis. In earlier studies, ROS were considered as toxic by-products of aerobic pathways of the metabolism. But in recent years, concept about ROS has changed because they also participate in developmental processes of plants by acting as signaling molecules. In plants, ROS regulate many developmental processes such as cell proliferation and differentiation, programmed cell death, seed germination, gravitropism, root hair growth and pollen tube development, senescence, etc. Despite much progress, a comprehensive update of advances in the understanding of the mechanisms evoked by ROS that mediate in cell proliferation and development are fragmentry and the matter of ROS perception and the signaling cascade remains open. Therefore, keeping in view the above facts, an attempt has been made in this article to summarize the recent findings regarding updates made in the regulatory action of ROS at various plant developmental stages, which are still not well-known. PMID:27729914

  16. Reactive oxygen species in response of plants to gravity stress

    NASA Astrophysics Data System (ADS)

    Jadko, Sergiy

    2016-07-01

    Reactive oxygen species (ROS) as second messengers can induce stress response of plants. Thioredoxins (Trx) and peroxiredoxins (Prx) can function as sensors and transmitters of the ROS in stress signaling and antioxidant response. 12-14 days old tissue culture of Arabidopsis thaliana have been investigated. Hypergravity stress was induced by centrifugation at 10 and 20 g during 30 and 90 min and than intensity of spontaneous chemiluminescence (SChL/ROS content), Trx and Prx activities were determined. All experiments were repeated from 3 to 5 times and the obtained data were statistically treated. In the tissue culture under development of the stress there were an increase in intensity of SChL and Trx and Prx activities. Thus, under hypergravity stress in the plant occurred early increase in the ROS level and the ROS induced the increase in the Trx and Prx activities. Prx and Trx can also participate in the formation of stress respons as acceptors and transducers of the redox signals. Increase in the activity of these enzymes primarily aimed at increasing of the total antioxidant activity in the cells to prevent of the plant to development of oxidative degradation by ROS.

  17. Reactive oxygen species (ROS) and cancer: Role of antioxidative nutraceuticals.

    PubMed

    Prasad, Sahdeo; Gupta, Subash C; Tyagi, Amit K

    2017-02-28

    Extensive research over the past half a century indicates that reactive oxygen species (ROS) play an important role in cancer. Although low levels of ROS can be beneficial, excessive accumulation can promote cancer. One characteristic of cancer cells that distinguishes them from normal cells is their ability to produce increased numbers of ROS and their increased dependence on an antioxidant defense system. ROS are produced as a byproduct intracellularly by mitochondria and other cellular elements and exogenously by pollutants, tobacco, smoke, drugs, xenobiotics, and radiation. ROS modulate various cell signaling pathways, which are primarily mediated through the transcription factors NF-κB and STAT3, hypoxia-inducible factor-1α, kinases, growth factors, cytokines and other proteins, and enzymes; these pathways have been linked to cellular transformation, inflammation, tumor survival, proliferation, invasion, angiogenesis, and metastasis of cancer. ROS are also associated with epigenetic changes in genes, which is helpful in diagnosing diseases. This review considers the role of ROS in the various stages of cancer development. Finally, we provide evidence that nutraceuticals derived from Mother Nature are highly effective in eliminating cancer cells.

  18. Reactive oxygen species: players in the cardiovascular effects of testosterone.

    PubMed

    Tostes, Rita C; Carneiro, Fernando S; Carvalho, Maria Helena C; Reckelhoff, Jane F

    2016-01-01

    Androgens are essential for the development and maintenance of male reproductive tissues and sexual function and for overall health and well being. Testosterone, the predominant and most important androgen, not only affects the male reproductive system, but also influences the activity of many other organs. In the cardiovascular system, the actions of testosterone are still controversial, its effects ranging from protective to deleterious. While early studies showed that testosterone replacement therapy exerted beneficial effects on cardiovascular disease, some recent safety studies point to a positive association between endogenous and supraphysiological levels of androgens/testosterone and cardiovascular disease risk. Among the possible mechanisms involved in the actions of testosterone on the cardiovascular system, indirect actions (changes in the lipid profile, insulin sensitivity, and hemostatic mechanisms, modulation of the sympathetic nervous system and renin-angiotensin-aldosterone system), as well as direct actions (modulatory effects on proinflammatory enzymes, on the generation of reactive oxygen species, nitric oxide bioavailability, and on vasoconstrictor signaling pathways) have been reported. This mini-review focuses on evidence indicating that testosterone has prooxidative actions that may contribute to its deleterious actions in the cardiovascular system. The controversial effects of testosterone on ROS generation and oxidant status, both prooxidant and antioxidant, in the cardiovascular system and in cells and tissues of other systems are reviewed.

  19. Reactive oxygen species a double-edged sword for mesothelioma

    PubMed Central

    Catalani, Simona; Galati, Rossella

    2015-01-01

    It is well known that oxidative stress can lead to chronic inflammation which, in turn, could mediate most chronic diseases including cancer. Oxidants have been implicated in the activity of crocidolite and amosite, the most powerful types of asbestos associated to the occurrence of mesothelioma. Currently rates of mesothelioma are rising and estimates indicate that the incidence of mesothelioma will peak within the next 10–15 years in the western world, while in Japan the peak is predicted not to occur until 40 years from now. Although the use of asbestos has been banned in many countries around the world, production of and the potentially hazardous exposure to asbestos is still present with locally high incidences of mesothelioma. Today a new man-made material, carbon nanotubes, has arisen as a concern; carbon nanotubes may display ‘asbestos-like’ pathogenicity with mesothelioma induction potential. Carbon nanotubes resulted in the greatest reactive oxygen species generation. How oxidative stress activates inflammatory pathways leading to the transformation of a normal cell to a tumor cell, to tumor cell survival, proliferation, invasion, angiogenesis, chemoresistance, and radioresistance, is the aim of this review. PMID:26078352

  20. Generation of reactive oxygen species from silicon nanowires.

    PubMed

    Leonard, Stephen S; Cohen, Guy M; Kenyon, Allison J; Schwegler-Berry, Diane; Fix, Natalie R; Bangsaruntip, Sarunya; Roberts, Jenny R

    2014-01-01

    Processing and synthesis of purified nanomaterials of diverse composition, size, and properties is an evolving process. Studies have demonstrated that some nanomaterials have potential toxic effects and have led to toxicity research focusing on nanotoxicology. About two million workers will be employed in the field of nanotechnology over the next 10 years. The unknown effects of nanomaterials create a need for research and development of techniques to identify possible toxicity. Through a cooperative effort between National Institute for Occupational Safety and Health and IBM to address possible occupational exposures, silicon-based nanowires (SiNWs) were obtained for our study. These SiNWs are anisotropic filamentary crystals of silicon, synthesized by the vapor-liquid-solid method and used in bio-sensors, gas sensors, and field effect transistors. Reactive oxygen species (ROS) can be generated when organisms are exposed to a material causing cellular responses, such as lipid peroxidation, H2O2 production, and DNA damage. SiNWs were assessed using three different in vitro environments (H2O2, RAW 264.7 cells, and rat alveolar macrophages) for ROS generation and possible toxicity identification. We used electron spin resonance, analysis of lipid peroxidation, measurement of H2O2 production, and the comet assay to assess generation of ROS from SiNW and define possible mechanisms. Our results demonstrate that SiNWs do not appear to be significant generators of free radicals.

  1. Geochemical production of reactive oxygen species from biogeochemically reduced Fe.

    PubMed

    Murphy, Sarah A; Solomon, Benson M; Meng, Shengnan; Copeland, Justin M; Shaw, Timothy J; Ferry, John L

    2014-04-01

    The photochemical reduction of Fe(III) complexes to Fe(II) is a well-known initiation step for the production of reactive oxygen species (ROS) in sunlit waters. Here we show a geochemical mechanism for the same in dark environments based on the tidally driven, episodic movement of anoxic groundwaters through oxidized, Fe(III) rich sediments. Sediment samples were collected from the top 5 cm of sediment in a saline tidal creek in the estuary at Murrell's Inlet, South Carolina and characterized with respect to total Fe, acid volatile sulfides, and organic carbon content. These sediments were air-dried, resuspended in aerated solution, then exposed to aqueous sulfide at a range of concentrations chosen to replicate the conditions characteristic of a tidal cycle, beginning with low tide. No detectable ROS production occurred from this process in the dark until sulfide was added. Sulfide addition resulted in the rapid production of hydrogen peroxide, with maximum concentrations of 3.85 μM. The mechanism of hydrogen peroxide production was tested using a simplified three factor representation of the system based on hydrogen sulfide, Fe(II) and Fe(III). The resulting predictive model for maximum hydrogen peroxide agreed with measured hydrogen peroxide in field-derived samples at the 95% level of confidence, although with a persistent negative bias suggesting a minor undiscovered peroxide source in sediments.

  2. Mechanism of teratogenesis: electron transfer, reactive oxygen species, and antioxidants.

    PubMed

    Kovacic, Peter; Somanathan, Ratnasamy

    2006-12-01

    Teratogenesis has been a topic of increasing interest and concern in recent years, generating controversy in association with danger to humans and other living things. A veritable host of chemicals is known to be involved, encompassing a wide variety of classes, both organic and inorganic. Contact with these chemicals is virtually unavoidable due to contamination of air, water, ground, food, beverages, and household items, as well as exposure to medicinals. The resulting adverse effects on reproduction are numerous. There is uncertainty regarding the mode of action of these chemicals, although various theories have been advanced, e.g., disruption of the central nervous system (CNS), DNA attack, enzyme inhibition, interference with hormonal action, and insult to membranes, proteins, and mitochondria. This review provides extensive evidence for involvement of oxidative stress (OS) and electron transfer (ET) as a unifying theme. Successful application of the mechanistic approach is made to all of the main classes of toxins, in addition to large numbers of miscellaneous types. We believe it is not coincidental that the vast majority of these substances incorporate ET functionalities (quinone, metal complex, ArNO2, or conjugated iminium) either per se or in metabolites, potentially giving rise to reactive oxygen species (ROS) by redox cycling. Some categories, e.g., peroxides and radiation, appear to generate ROS by non-ET routes. Other mechanisms are briefly addressed; a multifaceted approach to mode of action appears to be the most logical. Our framework should increase understanding and contribute to preventative measures, such as use of antioxidants.

  3. Redox Roles of Reactive Oxygen Species in Cardiovascular Diseases

    PubMed Central

    He, Feng; Zuo, Li

    2015-01-01

    Cardiovascular disease (CVD), a major cause of mortality in the world, has been extensively studied over the past decade. However, the exact mechanism underlying its pathogenesis has not been fully elucidated. Reactive oxygen species (ROS) play a pivotal role in the progression of CVD. Particularly, ROS are commonly engaged in developing typical characteristics of atherosclerosis, one of the dominant CVDs. This review will discuss the involvement of ROS in atherosclerosis, specifically their effect on inflammation, disturbed blood flow and arterial wall remodeling. Pharmacological interventions target ROS in order to alleviate oxidative stress and CVD symptoms, yet results are varied due to the paradoxical role of ROS in CVD. Lack of effectiveness in clinical trials suggests that understanding the exact role of ROS in the pathophysiology of CVD and developing novel treatments, such as antioxidant gene therapy and nanotechnology-related antioxidant delivery, could provide a therapeutic advance in treating CVDs. While genetic therapies focusing on specific antioxidant expression seem promising in CVD treatments, multiple technological challenges exist precluding its immediate clinical applications. PMID:26610475

  4. Salicylic acid signaling inhibits apoplastic reactive oxygen species signaling

    PubMed Central

    2014-01-01

    Background Reactive oxygen species (ROS) are used by plants as signaling molecules during stress and development. Given the amount of possible challenges a plant face from their environment, plants need to activate and prioritize between potentially conflicting defense signaling pathways. Until recently, most studies on signal interactions have focused on phytohormone interaction, such as the antagonistic relationship between salicylic acid (SA)-jasmonic acid and cytokinin-auxin. Results In this study, we report an antagonistic interaction between SA signaling and apoplastic ROS signaling. Treatment with ozone (O3) leads to a ROS burst in the apoplast and induces extensive changes in gene expression and elevation of defense hormones. However, Arabidopsis thaliana dnd1 (defense no death1) exhibited an attenuated response to O3. In addition, the dnd1 mutant displayed constitutive expression of defense genes and spontaneous cell death. To determine the exact process which blocks the apoplastic ROS signaling, double and triple mutants involved in various signaling pathway were generated in dnd1 background. Simultaneous elimination of SA-dependent and SA-independent signaling components from dnd1 restored its responsiveness to O3. Conversely, pre-treatment of plants with SA or using mutants that constitutively activate SA signaling led to an attenuation of changes in gene expression elicited by O3. Conclusions Based upon these findings, we conclude that plants are able to prioritize the response between ROS and SA via an antagonistic action of SA and SA signaling on apoplastic ROS signaling. PMID:24898702

  5. Reactive oxygen species, nutrition, hypoxia and diseases: Problems solved?

    PubMed Central

    Görlach, Agnes; Dimova, Elitsa Y.; Petry, Andreas; Martínez-Ruiz, Antonio; Hernansanz-Agustín, Pablo; Rolo, Anabela P.; Palmeira, Carlos M.; Kietzmann, Thomas

    2015-01-01

    Within the last twenty years the view on reactive oxygen species (ROS) has changed; they are no longer only considered to be harmful but also necessary for cellular communication and homeostasis in different organisms ranging from bacteria to mammals. In the latter, ROS were shown to modulate diverse physiological processes including the regulation of growth factor signaling, the hypoxic response, inflammation and the immune response. During the last 60–100 years the life style, at least in the Western world, has changed enormously. This became obvious with an increase in caloric intake, decreased energy expenditure as well as the appearance of alcoholism and smoking; These changes were shown to contribute to generation of ROS which are, at least in part, associated with the occurrence of several chronic diseases like adiposity, atherosclerosis, type II diabetes, and cancer. In this review we discuss aspects and problems on the role of intracellular ROS formation and nutrition with the link to diseases and their problematic therapeutical issues. PMID:26339717

  6. Imaging Reactive Oxygen Species-Induced Modifications in Living Systems

    PubMed Central

    Maulucci, Giuseppe; Bačić, Goran; Bridal, Lori; Schmidt, Harald H.H.W.; Tavitian, Bertrand; Viel, Thomas; Utsumi, Hideo; Yalçın, A. Süha

    2016-01-01

    Abstract Significance: Reactive Oxygen Species (ROS) may regulate signaling, ion channels, transcription factors, and biosynthetic processes. ROS-related diseases can be due to either a shortage or an excess of ROS. Recent Advances: Since the biological activity of ROS depends on not only concentration but also spatiotemporal distribution, real-time imaging of ROS, possibly in vivo, has become a need for scientists, with potential for clinical translation. New imaging techniques as well as new contrast agents in clinically established modalities were developed in the previous decade. Critical Issues: An ideal imaging technique should determine ROS changes with high spatio-temporal resolution, detect physiologically relevant variations in ROS concentration, and provide specificity toward different redox couples. Furthermore, for in vivo applications, bioavailability of sensors, tissue penetration, and a high signal-to-noise ratio are additional requirements to be satisfied. Future Directions: None of the presented techniques fulfill all requirements for clinical translation. The obvious way forward is to incorporate anatomical and functional imaging into a common hybrid-imaging platform. Antioxid. Redox Signal. 24, 939–958. PMID:27139586

  7. Serum levels of reactive oxygen species (ROS) in the bitch.

    PubMed

    Rizzo, Annalisa; Roscino, Maria Teresa; Minoia, Giuseppe; Trisolini, Carmelinda; Spedicato, Massimo; Mutinati, Maddalena; Pantaleo, Marianna; Jirillo, Felicita; Sciorsci, Raffaele L

    2009-06-01

    The aim of this study was to determine the serum concentrations of reactive oxygen species (ROS) during the different phases of the estrous cycle in the bitch, in order to establish their physiological values. 56 healthy mixed-breed bitches were enrolled at this purpose and divided into 4 groups, standing on the different phases of the estrus cycle. Blood samples were collected in all groups and serum ROS concentrations were determined. Proestral concentrations were statistically higher than anestral ones, and statistically lower than those found in estrus (p<0.001). The highest concentrations of ROS were detected at estrus, that is, in the peri-ovulatory period. This sharp increase in ROS concentrations is related to the acute inflammatory process underlying ovulation and to the increase in immune and metabolic activities, cytological changes and myometrial contractility promoted by the high levels of estrogens. In diestrus, the mean concentration of ROS decreases. This reduction did not show any statistically significant difference with the mean value observed in proestrus. In this phase, in fact, the high concentrations of progesterone, exerting an antioxidant and immunodepressive effect, justify the lower mean concentration of ROS detected. In anestrus, the lowest concentrations of ROS were observed, for the reduced metabolic and endocrine activity occurring in this phase of the estrous cycle. In conclusion our results establish the physiologic levels of ROS during the estrous cycle in the bitch and reflect the endocrine morphologic and metabolic changes occurring during it.

  8. Mitochondrial alpha-ketoglutarate dehydrogenase complex generates reactive oxygen species.

    PubMed

    Starkov, Anatoly A; Fiskum, Gary; Chinopoulos, Christos; Lorenzo, Beverly J; Browne, Susan E; Patel, Mulchand S; Beal, M Flint

    2004-09-08

    Mitochondria-produced reactive oxygen species (ROS) are thought to contribute to cell death caused by a multitude of pathological conditions. The molecular sites of mitochondrial ROS production are not well established but are generally thought to be located in complex I and complex III of the electron transport chain. We measured H(2)O(2) production, respiration, and NADPH reduction level in rat brain mitochondria oxidizing a variety of respiratory substrates. Under conditions of maximum respiration induced with either ADP or carbonyl cyanide p-trifluoromethoxyphenylhydrazone,alpha-ketoglutarate supported the highest rate of H(2)O(2) production. In the absence of ADP or in the presence of rotenone, H(2)O(2) production rates correlated with the reduction level of mitochondrial NADPH with various substrates, with the exception of alpha-ketoglutarate. Isolated mitochondrial alpha-ketoglutarate dehydrogenase (KGDHC) and pyruvate dehydrogenase (PDHC) complexes produced superoxide and H(2)O(2). NAD(+) inhibited ROS production by the isolated enzymes and by permeabilized mitochondria. We also measured H(2)O(2) production by brain mitochondria isolated from heterozygous knock-out mice deficient in dihydrolipoyl dehydrogenase (Dld). Although this enzyme is a part of both KGDHC and PDHC, there was greater impairment of KGDHC activity in Dld-deficient mitochondria. These mitochondria also produced significantly less H(2)O(2) than mitochondria isolated from their littermate wild-type mice. The data strongly indicate that KGDHC is a primary site of ROS production in normally functioning mitochondria.

  9. Are Reactive Oxygen Species Always Detrimental to Pathogens?

    PubMed Central

    Bozza, Marcelo T.

    2014-01-01

    Abstract Reactive oxygen species (ROS) are deadly weapons used by phagocytes and other cell types, such as lung epithelial cells, against pathogens. ROS can kill pathogens directly by causing oxidative damage to biocompounds or indirectly by stimulating pathogen elimination by various nonoxidative mechanisms, including pattern recognition receptors signaling, autophagy, neutrophil extracellular trap formation, and T-lymphocyte responses. Thus, one should expect that the inhibition of ROS production promote infection. Increasing evidences support that in certain particular infections, antioxidants decrease and prooxidants increase pathogen burden. In this study, we review the classic infections that are controlled by ROS and the cases in which ROS appear as promoters of infection, challenging the paradigm. We discuss the possible mechanisms by which ROS could promote particular infections. These mechanisms are still not completely clear but include the metabolic effects of ROS on pathogen physiology, ROS-induced damage to the immune system, and ROS-induced activation of immune defense mechanisms that are subsequently hijacked by particular pathogens to act against more effective microbicidal mechanisms of the immune system. The effective use of antioxidants as therapeutic agents against certain infections is a realistic possibility that is beginning to be applied against viruses. Antioxid. Redox Signal. 20, 1000–1037. PMID:23992156

  10. Matairesinol inhibits angiogenesis via suppression of mitochondrial reactive oxygen species

    SciTech Connect

    Lee, Boram; Kim, Ki Hyun; Jung, Hye Jin; Kwon, Ho Jeong

    2012-04-27

    Highlights: Black-Right-Pointing-Pointer Matairesinol suppresses mitochondrial ROS generation during hypoxia. Black-Right-Pointing-Pointer Matairesinol exhibits potent anti-angiogenic activity both in vitro and in vivo. Black-Right-Pointing-Pointer Matairesinol could be a basis for the development of novel anti-angiogenic agents. -- Abstract: Mitochondrial reactive oxygen species (mROS) are involved in cancer initiation and progression and function as signaling molecules in many aspects of hypoxia and growth factor-mediated signaling. Here we report that matairesinol, a natural small molecule identified from the cell-based screening of 200 natural plants, suppresses mROS generation resulting in anti-angiogenic activity. A non-toxic concentration of matairesinol inhibited the proliferation of human umbilical vein endothelial cells. The compound also suppressed in vitro angiogenesis of tube formation and chemoinvasion, as well as in vivo angiogenesis of the chorioallantoic membrane at non-toxic doses. Furthermore, matairesinol decreased hypoxia-inducible factor-1{alpha} in hypoxic HeLa cells. These results demonstrate that matairesinol could function as a novel angiogenesis inhibitor by suppressing mROS signaling.

  11. Reactive oxygen species: players in the cardiovascular effects of testosterone

    PubMed Central

    Carneiro, Fernando S.; Carvalho, Maria Helena C.; Reckelhoff, Jane F.

    2015-01-01

    Androgens are essential for the development and maintenance of male reproductive tissues and sexual function and for overall health and well being. Testosterone, the predominant and most important androgen, not only affects the male reproductive system, but also influences the activity of many other organs. In the cardiovascular system, the actions of testosterone are still controversial, its effects ranging from protective to deleterious. While early studies showed that testosterone replacement therapy exerted beneficial effects on cardiovascular disease, some recent safety studies point to a positive association between endogenous and supraphysiological levels of androgens/testosterone and cardiovascular disease risk. Among the possible mechanisms involved in the actions of testosterone on the cardiovascular system, indirect actions (changes in the lipid profile, insulin sensitivity, and hemostatic mechanisms, modulation of the sympathetic nervous system and renin-angiotensin-aldosterone system), as well as direct actions (modulatory effects on proinflammatory enzymes, on the generation of reactive oxygen species, nitric oxide bioavailability, and on vasoconstrictor signaling pathways) have been reported. This mini-review focuses on evidence indicating that testosterone has prooxidative actions that may contribute to its deleterious actions in the cardiovascular system. The controversial effects of testosterone on ROS generation and oxidant status, both prooxidant and antioxidant, in the cardiovascular system and in cells and tissues of other systems are reviewed. PMID:26538238

  12. Soot-driven reactive oxygen species formation from incense burning.

    PubMed

    Chuang, Hsiao-Chi; Jones, Tim P; Lung, Shih-Chun C; BéruBé, Kelly A

    2011-10-15

    This study investigated the effects of reactive oxygen species (ROS) generated as a function of the physicochemistry of incense particulate matter (IPM), diesel exhaust particles (DEP) and carbon black (CB). Microscopical and elemental analyses were used to determine particle morphology and inorganic compounds. ROS was determined using the reactive dye, Dichlorodihydrofluorescin (DCFH), and the Plasmid Scission Assay (PSA), which determine DNA damage. Two common types of soot were observed within IPM, including nano-soot and micro-soot, whereas DEP and CB mainly consisted of nano-soot. These PM were capable of causing oxidative stress in a dose-dependent manner, especially IPM and DEP. A dose of IPM (36.6-102.3μg/ml) was capable of causing 50% oxidative DNA damage. ROS formation was positively correlated to smaller nano-soot aggregates and bulk metallic compounds, particularly Cu. These observations have important implications for respiratory health given that inflammation has been recognised as an important factor in the development of lung injury/diseases by oxidative stress. This study supports the view that ROS formation by combustion-derived PM is related to PM physicochemistry, and also provides new data for IPM.

  13. Reactive oxygen species and mitochondria: A nexus of cellular homeostasis.

    PubMed

    Dan Dunn, Joe; Alvarez, Luis Aj; Zhang, Xuezhi; Soldati, Thierry

    2015-12-01

    Reactive oxygen species (ROS) are integral components of multiple cellular pathways even though excessive or inappropriately localized ROS damage cells. ROS function as anti-microbial effector molecules and as signaling molecules that regulate such processes as NF-kB transcriptional activity, the production of DNA-based neutrophil extracellular traps (NETs), and autophagy. The main sources of cellular ROS are mitochondria and NADPH oxidases (NOXs). In contrast to NOX-generated ROS, ROS produced in the mitochondria (mtROS) were initially considered to be unwanted by-products of oxidative metabolism. Increasing evidence indicates that mtROS have been incorporated into signaling pathways including those regulating immune responses and autophagy. As metabolic hubs, mitochondria facilitate crosstalk between the metabolic state of the cell with these pathways. Mitochondria and ROS are thus a nexus of multiple pathways that determine the response of cells to disruptions in cellular homeostasis such as infection, sterile damage, and metabolic imbalance. In this review, we discuss the roles of mitochondria in the generation of ROS-derived anti-microbial effectors, the interplay of mitochondria and ROS with autophagy and the formation of DNA extracellular traps, and activation of the NLRP3 inflammasome by ROS and mitochondria.

  14. Generation of Reactive Oxygen Species from Silicon Nanowires

    PubMed Central

    Leonard, Stephen S; Cohen, Guy M; Kenyon, Allison J; Schwegler-Berry, Diane; Fix, Natalie R; Bangsaruntip, Sarunya; Roberts, Jenny R

    2014-01-01

    Processing and synthesis of purified nanomaterials of diverse composition, size, and properties is an evolving process. Studies have demonstrated that some nanomaterials have potential toxic effects and have led to toxicity research focusing on nanotoxicology. About two million workers will be employed in the field of nanotechnology over the next 10 years. The unknown effects of nanomaterials create a need for research and development of techniques to identify possible toxicity. Through a cooperative effort between National Institute for Occupational Safety and Health and IBM to address possible occupational exposures, silicon-based nanowires (SiNWs) were obtained for our study. These SiNWs are anisotropic filamentary crystals of silicon, synthesized by the vapor–liquid–solid method and used in bio-sensors, gas sensors, and field effect transistors. Reactive oxygen species (ROS) can be generated when organisms are exposed to a material causing cellular responses, such as lipid peroxidation, H2O2 production, and DNA damage. SiNWs were assessed using three different in vitro environments (H2O2, RAW 264.7 cells, and rat alveolar macrophages) for ROS generation and possible toxicity identification. We used electron spin resonance, analysis of lipid peroxidation, measurement of H2O2 production, and the comet assay to assess generation of ROS from SiNW and define possible mechanisms. Our results demonstrate that SiNWs do not appear to be significant generators of free radicals. PMID:25452695

  15. Reactive Oxygen Species, Apoptosis, Antimicrobial Peptides and Human Inflammatory Diseases

    PubMed Central

    Oyinloye, Babatunji Emmanuel; Adenowo, Abiola Fatimah; Kappo, Abidemi Paul

    2015-01-01

    Excessive free radical generation, especially reactive oxygen species (ROS) leading to oxidative stress in the biological system, has been implicated in the pathogenesis and pathological conditions associated with diverse human inflammatory diseases (HIDs). Although inflammation which is considered advantageous is a defensive mechanism in response to xenobiotics and foreign pathogen; as a result of cellular damage arising from oxidative stress, if uncontrolled, it may degenerate to chronic inflammation when the ROS levels exceed the antioxidant capacity. Therefore, in the normal resolution of inflammatory reactions, apoptosis is acknowledged to play a crucial role, while on the other hand, dysregulation in the induction of apoptosis by enhanced ROS production could also result in excessive apoptosis identified in the pathogenesis of HIDs. Apparently, a careful balance must be maintained in this complex environment. Antimicrobial peptides (AMPs) have been proposed in this review as an excellent candidate capable of playing prominent roles in maintaining this balance. Consequently, in novel drug design for the treatment and management of HIDs, AMPs are promising candidates owing to their size and multidimensional properties as well as their wide spectrum of activities and indications of reduced rate of resistance. PMID:25850012

  16. Reactive oxygen species and mitochondria: A nexus of cellular homeostasis

    PubMed Central

    Dan Dunn, Joe; Alvarez, Luis AJ; Zhang, Xuezhi; Soldati, Thierry

    2015-01-01

    Reactive oxygen species (ROS) are integral components of multiple cellular pathways even though excessive or inappropriately localized ROS damage cells. ROS function as anti-microbial effector molecules and as signaling molecules that regulate such processes as NF-kB transcriptional activity, the production of DNA-based neutrophil extracellular traps (NETs), and autophagy. The main sources of cellular ROS are mitochondria and NADPH oxidases (NOXs). In contrast to NOX-generated ROS, ROS produced in the mitochondria (mtROS) were initially considered to be unwanted by-products of oxidative metabolism. Increasing evidence indicates that mtROS have been incorporated into signaling pathways including those regulating immune responses and autophagy. As metabolic hubs, mitochondria facilitate crosstalk between the metabolic state of the cell with these pathways. Mitochondria and ROS are thus a nexus of multiple pathways that determine the response of cells to disruptions in cellular homeostasis such as infection, sterile damage, and metabolic imbalance. In this review, we discuss the roles of mitochondria in the generation of ROS-derived anti-microbial effectors, the interplay of mitochondria and ROS with autophagy and the formation of DNA extracellular traps, and activation of the NLRP3 inflammasome by ROS and mitochondria. PMID:26432659

  17. NSAIDs and Cardiovascular Diseases: Role of Reactive Oxygen Species

    PubMed Central

    Ghosh, Rajeshwary; Alajbegovic, Azra; Gomes, Aldrin V.

    2015-01-01

    Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most commonly used drugs worldwide. NSAIDs are used for a variety of conditions including pain, rheumatoid arthritis, and musculoskeletal disorders. The beneficial effects of NSAIDs in reducing or relieving pain are well established, and other benefits such as reducing inflammation and anticancer effects are also documented. The undesirable side effects of NSAIDs include ulcers, internal bleeding, kidney failure, and increased risk of heart attack and stroke. Some of these side effects may be due to the oxidative stress induced by NSAIDs in different tissues. NSAIDs have been shown to induce reactive oxygen species (ROS) in different cell types including cardiac and cardiovascular related cells. Increases in ROS result in increased levels of oxidized proteins which alters key intracellular signaling pathways. One of these key pathways is apoptosis which causes cell death when significantly activated. This review discusses the relationship between NSAIDs and cardiovascular diseases (CVD) and the role of NSAID-induced ROS in CVD. PMID:26457127

  18. Redox Mechanism of Reactive Oxygen Species in Exercise

    PubMed Central

    He, Feng; Li, Juan; Liu, Zewen; Chuang, Chia-Chen; Yang, Wenge; Zuo, Li

    2016-01-01

    It is well known that regular exercise can benefit health by enhancing antioxidant defenses in the body. However, unaccustomed and/or exhaustive exercise can generate excessive reactive oxygen species (ROS), leading to oxidative stress-related tissue damages and impaired muscle contractility. ROS are produced in both aerobic and anaerobic exercise. Mitochondria, NADPH oxidases and xanthine oxidases have all been identified as potential contributors to ROS production, yet the exact redox mechanisms underlying exercise-induced oxidative stress remain elusive. Interestingly, moderate exposure to ROS is necessary to induce body's adaptive responses such as the activation of antioxidant defense mechanisms. Dietary antioxidant manipulation can also reduce ROS levels and muscle fatigue, as well as enhance exercise recovery. To elucidate the complex role of ROS in exercise, this review updates on new findings of ROS origins within skeletal muscles associated with various types of exercises such as endurance, sprint and mountain climbing. In addition, we will examine the corresponding antioxidant defense systems as well as dietary manipulation against damages caused by ROS. PMID:27872595

  19. NO accounts completely for the oxygenated nitrogen species generated by enzymic L-arginine oxygenation.

    PubMed Central

    Mülsch, A; Vanin, A; Mordvintcev, P; Hauschildt, S; Busse, R

    1992-01-01

    We have assessed the stoichiometry of the nitric oxide (NO) synthase reaction by using a novel e.p.r. technique. NO generated by crude and partially purified NO synthase from endothelial cells and Escherichia coli-lipopolysaccharide-activated macrophages was trapped by a ferrous diethyldithiocarbamate complex dispersed in yeast. The paramagnetic ferrous mononitrosyl dithiocarbamate complex formed exhibited a characteristic e.p.r. signal at g perpendicular = 2.035 and g parallel = 2.02 with a triplet hyperfine structure (hfs) at g perpendicular. NO, 3-morpholinosydnonimine and S-nitroso-L-cysteine, but not nitrite or hydroxylamine, generated a similar e.p.r. signal. NO generated by NO synthase and by SIN-1 accumulated at a constant rate for 1 h, as measured by continuous e.p.r. registration at 37 degrees C. The formation of e.p.r.-detectable NO by NO synthases was inhibited by NG-nitro-L-arginine. Incubation with [15N]NG-L-arginine caused an e.p.r. signal with doublet hfs, indicating that the nitrosyl nitrogen derived exclusively from the guanidino nitrogen. The amount of NO generated by NO synthase as measured by e.p.r. technique was compared with formation of L-[3H]citrulline from L-[3H]arginine. NO and L-citrulline were detected at a 1:1 ratio with both NO synthase preparations. GSH and thiol depletion did not significantly affect NO synthase activity, excluding S-nitrosothiols as intermediates in the NO synthase reaction. We conclude that NO fully accounts for the immediate oxygenated nitrogen species derived from the enzymic oxygenation of L-arginine. PMID:1281408

  20. Reactive Oxygen Species (ROS) generation by lunar simulants

    NASA Astrophysics Data System (ADS)

    Kaur, Jasmeet; Rickman, Douglas; Schoonen, Martin A.

    2016-05-01

    The current interest in human exploration of the Moon and past experiences of Apollo astronauts has rekindled interest into the possible harmful effects of lunar dust on human health. In comparison to the Apollo-era explorations, human explorers may be weeks on the Moon, which will raise the risk of inhalation exposure. The mineralogical composition of lunar dust is well documented, but its effects on human health are not fully understood. With the aim of understanding the reactivity of dusts that may be encountered on geologically different lunar terrains, we have studied Reactive Oxygen Species (ROS) generation by a suite of lunar simulants of different mineralogical-chemical composition dispersed in water and Simulated Lung Fluid (SLF). To further explore the reactivity of simulants under lunar environmental conditions, we compared the reactivity of simulants both in air and inert atmosphere. As the impact of micrometeorites with consequent shock-induced stresses is a major environmental factor on the Moon, we also studied the effect of mechanical stress on samples. Mechanical stress was induced by hand crushing the samples both in air and inert atmosphere. The reactivity of samples after crushing was analyzed for a period of up to nine days. Hydrogen peroxide (H2O2) in water and SLF was analyzed by an in situ electrochemical probe and hydroxyl radical (•OH) by Electron Spin Resonance (ESR) spectroscopy and Adenine probe. Out of all simulants, CSM-CL-S was found to be the most reactive simulant followed by OB-1 and then JSC-1A simulant. The overall reactivity of samples in the inert atmosphere was higher than in air. Fresh crushed samples showed a higher level of reactivity than uncrushed samples. Simulant samples treated to create agglutination, including the formation of zero-valent iron, showed less reactivity than untreated simulants. ROS generation in SLF is initially slower than in deionized water (DI), but the ROS formation is sustained for as long as 7

  1. Exposure of Bacterial Biofilms to Electrical Current Leads to Cell Death Mediated in Part by Reactive Oxygen Species

    PubMed Central

    Brinkman, Cassandra L.; Schmidt-Malan, Suzannah M.; Karau, Melissa J.; Greenwood-Quaintance, Kerryl; Hassett, Daniel J.; Mandrekar, Jayawant N.

    2016-01-01

    Bacterial biofilms may form on indwelling medical devices such as prosthetic joints, heart valves and catheters, causing challenging-to-treat infections. We have previously described the ‘electricidal effect’, in which bacterial biofilms are decreased following exposure to direct electrical current. Herein, we sought to determine if the decreased bacterial quantities are due to detachment of biofilms or cell death and to investigate the role that reactive oxygen species (ROS) play in the observed effect. Using confocal and electron microscopy and flow cytometry, we found that direct current (DC) leads to cell death and changes in the architecture of biofilms formed by Gram-positive and Gram-negative bacteria. Reactive oxygen species (ROS) appear to play a role in DC-associated cell death, as there was an increase in ROS-production by Staphylococcus aureus and Staphylococcus epidermidis biofilms following exposure to DC. An increase in the production of ROS response enzymes catalase and superoxide dismutase (SOD) was observed for S. aureus, S. epidermidis and Pseudomonas aeruginosa biofilms following exposure to DC. Additionally, biofilms were protected from cell death when supplemented with antioxidants and oxidant scavengers, including catalase, mannitol and Tempol. Knocking out SOD (sodAB) in P. aeruginosa led to an enhanced DC effect. Microarray analysis of P. aeruginosa PAO1 showed transcriptional changes in genes related to the stress response and cell death. In conclusion, the electricidal effect results in death of bacteria in biofilms, mediated, at least in part, by production of ROS. PMID:27992529

  2. Inorganic Polyphosphates Regulate Hexokinase Activity and Reactive Oxygen Species Generation in Mitochondria of Rhipicephalus (Boophilus) microplus Embryo

    PubMed Central

    Fraga, Amanda; Moraes, Jorge; da Silva, José Roberto; Costa, Evenilton P.; Menezes, Jackson; da Silva Vaz Jr, Itabajara; Logullo, Carlos; da Fonseca, Rodrigo Nunes; Campos, Eldo

    2013-01-01

    The physiological roles of polyphosphates (poly P) recently found in arthropod mitochondria remain obscure. Here, the possible involvement of poly P with reactive oxygen species generation in mitochondria of Rhipicephalus microplus embryos was investigated. Mitochondrial hexokinase and scavenger antioxidant enzymes, such as superoxide dismutase, catalase, and glutathione reductase were assayed during embryogenesis of R. microplus. The influence of poly P3 and poly P15 were analyzed during the period of higher enzymatic activity during embryogenesis. Both poly Ps inhibited hexokinase activity by up to 90% and, interestingly, the mitochondrial membrane exopolyphosphatase activity was stimulated by the hexokinase reaction product, glucose-6-phosphate. Poly P increased hydrogen peroxide generation in mitochondria in a situation where mitochondrial hexokinase is also active. The superoxide dismutase, catalase and glutathione reductase activities were higher during embryo cellularization, at the end of embryogenesis and during embryo segmentation, respectively. All of the enzymes were stimulated by poly P3. However, superoxide dismutase was not affected by poly P15, catalase activity was stimulated only at high concentrations and glutathione reductase was the only enzyme that was stimulated in the same way by both poly Ps. Altogether, our results indicate that inorganic polyphosphate and mitochondrial membrane exopolyphosphatase regulation can be correlated with the generation of reactive oxygen species in the mitochondria of R. microplus embryos. PMID:23983617

  3. Reactive Oxygen and Nitrogen Species in Defense/Stress Responses Activated by Chitosan in Sycamore Cultured Cells

    PubMed Central

    Malerba, Massimo; Cerana, Raffaella

    2015-01-01

    Chitosan (CHT) is a non-toxic and inexpensive compound obtained by deacetylation of chitin, the main component of the exoskeleton of arthropods as well as of the cell walls of many fungi. In agriculture CHT is used to control numerous diseases on various horticultural commodities but, although different mechanisms have been proposed, the exact mode of action of CHT is still unknown. In sycamore (Acer pseudoplatanus L.) cultured cells, CHT induces a set of defense/stress responses that includes production of H2O2 and nitric oxide (NO). We investigated the possible signaling role of these reactive molecules in some CHT-induced responses by means of inhibitors of production and/or scavengers. The results show that both reactive nitrogen and oxygen species are not only a mere symptom of stress conditions but are involved in the responses induced by CHT in sycamore cells. In particular, NO appears to be involved in a cell death form induced by CHT that shows apoptotic features like DNA fragmentation, increase in caspase-3-like activity and release of cytochrome c from the mitochondrion. On the contrary, reactive oxygen species (ROS) appear involved in a cell death form induced by CHT that does not show these apoptotic features but presents increase in lipid peroxidation. PMID:25642757

  4. 3,3'-Dihydroxyisorenieratene prevents UV-induced formation of reactive oxygen species and the release of protein-bound zinc ions in human skin fibroblasts.

    PubMed

    Lutter, Kaya; De Spirt, Silke; Kock, Sebastian; Kröncke, Klaus-Dietrich; Martin, Hans-Dieter; Wagener, Tanja; Stahl, Wilhelm

    2010-02-01

    3,3'-Dihydroxyisorenieratene (DHIR) is a structurally unusual carotenoid exhibiting bifunctional antioxidant properties. It is synthesized by Brevibacterium linens, used in dairy industry for the production of red smear cheeses. The compound protects cellular structures against photo-oxidative damage and inhibits the UV-dependent formation of thymidine dimers. Here we show that DHIR prevents a UV-induced intracellular release of zinc ions from proteins in human dermal fibroblasts. The effect is correlated with a decreased formation of intracellular reactive oxygen species. In contrast, zinc release from cellular proteins induced by hyperthermia is not affected by pretreatment of cells with the antioxidant DHIR. It is suggested that the intracellular zinc release upon UV irradiation is due to oxidative modifications of the zinc ligands in proteins (e.g. cysteine) and that protection by DHIR is due to intracellular scavenging of reactive oxygen species generated in photo-oxidation.

  5. Involvement of Cytochrome P450 in Reactive Oxygen Species Formation and Cancer.

    PubMed

    Hrycay, Eugene G; Bandiera, Stelvio M

    2015-01-01

    This review examines the involvement of cytochrome P450 (CYP) enzymes in the formation of reactive oxygen species in biological systems and discusses the possible involvement of reactive oxygen species and CYP enzymes in cancer. Reactive oxygen species are formed in biological systems as byproducts of the reduction of molecular oxygen and include the superoxide radical anion (∙O2-), hydrogen peroxide (H2O2), hydroxyl radical (∙OH), hydroperoxyl radical (HOO∙), singlet oxygen ((1)O2), and peroxyl radical (ROO∙). Two endogenous sources of reactive oxygen species are the mammalian CYP-dependent microsomal electron transport system and the mitochondrial electron transport chain. CYP enzymes catalyze the oxygenation of an organic substrate and the simultaneous reduction of molecular oxygen. If the transfer of oxygen to a substrate is not tightly controlled, uncoupling occurs and leads to the formation of reactive oxygen species. Reactive oxygen species are capable of causing oxidative damage to cellular membranes and macromolecules that can lead to the development of human diseases such as cancer. In normal cells, intracellular levels of reactive oxygen species are maintained in balance with intracellular biochemical antioxidants to prevent cellular damage. Oxidative stress occurs when this critical balance is disrupted. Topics covered in this review include the role of reactive oxygen species in intracellular cell signaling and the relationship between CYP enzymes and cancer. Outlines of CYP expression in neoplastic tissues, CYP enzyme polymorphism and cancer risk, CYP enzymes in cancer therapy and the metabolic activation of chemical procarcinogens by CYP enzymes are also provided.

  6. A case of mistaken identity: are reactive oxygen species actually reactive sulfide species?

    PubMed

    DeLeon, Eric R; Gao, Yan; Huang, Evelyn; Arif, Maaz; Arora, Nitin; Divietro, Alexander; Patel, Shivali; Olson, Kenneth R

    2016-04-01

    Stepwise one-electron reduction of oxygen to water produces reactive oxygen species (ROS) that are chemically and biochemically similar to reactive sulfide species (RSS) derived from one-electron oxidations of hydrogen sulfide to elemental sulfur. Both ROS and RSS are endogenously generated and signal via protein thiols. Given the similarities between ROS and RSS, we wondered whether extant methods for measuring the former would also detect the latter. Here, we compared ROS to RSS sensitivity of five common ROS methods: redox-sensitive green fluorescent protein (roGFP), 2', 7'-dihydrodichlorofluorescein, MitoSox Red, Amplex Red, and amperometric electrodes. All methods detected RSS and were as, or more, sensitive to RSS than to ROS. roGFP, arguably the "gold standard" for ROS measurement, was more than 200-fold more sensitive to the mixed polysulfide H2Sn(n = 1-8) than to H2O2 These findings suggest that RSS may be far more prevalent in intracellular signaling than previously appreciated and that the contribution of ROS may be overestimated. This conclusion is further supported by the observation that estimated daily sulfur metabolism and ROS production are approximately equal and the fact that both RSS and antioxidant mechanisms have been present since the origin of life, nearly 4 billion years ago, long before the rise in environmental oxygen 600 million years ago. Although ROS are assumed to be the most biologically relevant oxidants, our results question this paradigm. We also anticipate our findings will direct attention toward development of novel and clinically relevant anti-(RSS)-oxidants.

  7. Hydrogen peroxide inducible clone-5 mediates reactive oxygen species signaling for hepatocellular carcinoma progression

    PubMed Central

    Wu, Jia-Ru; Hu, Chi-Tan; You, Ren-In; Pan, Siou-Mei; Cheng, Chuan-Chu; Lee, Ming-Che; Wu, Chao-Chuan; Chang, Yao-Jen; Lin, Shu-Chuan; Chen, Chang-Shan; Lin, Teng-Yi; Wu, Wen-Sheng

    2015-01-01

    One of the signaling components involved in hepatocellular carcinoma (HCC) progression is the focal adhesion adaptor paxillin. Hydrogen peroxide inducible clone-5 (Hic-5), one of the paralogs of paxillin, exhibits many biological functions distinct from paxillin, but may cooperate with paxillin to trigger tumor progression. Screening of Hic-5 in 145 surgical HCCs demonstrated overexpression of Hic-5 correlated well with intra- and extra-hepatic metastasis. Hic-5 highly expressed in the patient derived HCCs with high motility such as HCC329 and HCC353 but not in the HCCs with low motility such as HCC340. Blockade of Hic-5 expression prevented constitutive migration of HCC329 and HCC353 and HGF-induced cell migration of HCC340. HCC329Hic-5(−), HCC353Hic-5(−), HCC372Hic-5(−), the HCCs stably depleted of Hic-5, exhibited reduced motility compared with each HCC expressing Scramble shRNA. Moreover, intra/extrahepatic metastasis of HCC329Hic-5(−) in SCID mice greatly decreased compared with HCC329Scramble. On the other hand, ectopic Hic-5 expression in HCC340 promoted its progression. Constitutive and HGF-induced Hic-5 expression in HCCs were suppressed by the reactive oxygen species (ROS) scavengers catalase and dithiotheritol and c-Jun N-terminal kinase (JNK) inhibitor SP600125. On the contrary, depletion of Hic-5 blocked constitutive and HGF-induced ROS generation and JNK phosphorylation in HCCs. Also, ectopic expression of Hic-5 enhanced ROS generation and JNK phosphorylation. These highlighted that Hic-5 plays a central role in the positive feedback ROS-JNK signal cascade. Finally, the Chinese herbal derived anti-HCC peptide LZ-8 suppressed constitutive Hic-5 expression and JNK phosphorylation. In conclusion, Hic-5 mediates ROS-JNK signaling and may serve as a therapeutic target for prevention of HCC progression. PMID:26416447

  8. Trypanosoma cruzi Needs a Signal Provided by Reactive Oxygen Species to Infect Macrophages

    PubMed Central

    Goes, Grazielle R.; Rocha, Peter S.; Diniz, Aline R. S.; Aguiar, Pedro H. N.; Machado, Carlos R.; Vieira, Leda Q.

    2016-01-01

    Background During Trypanosoma cruzi infection, macrophages produce reactive oxygen species (ROS) in a process called respiratory burst. Several works have aimed to elucidate the role of ROS during T. cruzi infection and the results obtained are sometimes contradictory. T. cruzi has a highly efficiently regulated antioxidant machinery to deal with the oxidative burst, but the parasite macromolecules, particularly DNA, may still suffer oxidative damage. Guanine (G) is the most vulnerable base and its oxidation results in formation of 8-oxoG, a cellular marker of oxidative stress. Methodology/Principal Findings In order to investigate the contribution of ROS in T. cruzi survival and infection, we utilized mice deficient in the gp91phox (Phox KO) subunit of NADPH oxidase and parasites that overexpress the enzyme EcMutT (from Escherichia coli) or TcMTH (from T. cruzi), which is responsible for removing 8-oxo-dGTP from the nucleotide pool. The modified parasites presented enhanced replication inside murine inflammatory macrophages from C57BL/6 WT mice when compared with control parasites. Interestingly, when Phox KO macrophages were infected with these parasites, we observed a decreased number of all parasites when compared with macrophages from C57BL/6 WT. Scavengers for ROS also decreased parasite growth in WT macrophages. In addition, treatment of macrophages or parasites with hydrogen peroxide increased parasite replication in Phox KO mice and in vivo. Conclusions Our results indicate a paradoxical role for ROS since modified parasites multiply better inside macrophages, but proliferation is significantly reduced when ROS is removed from the host cell. Our findings suggest that ROS can work like a signaling molecule, contributing to T. cruzi growth inside the cells. PMID:27035573

  9. Aging and estrogen alter endothelial reactivity to reactive oxygen species in coronary arterioles.

    PubMed

    Kang, Lori S; Chen, Bei; Reyes, Rafael A; Leblanc, Amanda J; Teng, Bunyen; Mustafa, S Jamal; Muller-Delp, Judy M

    2011-06-01

    Endothelium-dependent, nitric oxide (NO)-mediated vasodilation can be impaired by reactive oxygen species (ROS), and this deleterious effect of ROS on NO availability may increase with aging. Endothelial function declines rapidly after menopause, possibly because of loss of circulating estrogen and its antioxidant effects. The purpose of the current study was to determine the role of O(2)(-) and H(2)O(2) in regulating flow-induced dilation in coronary arterioles of young (6-mo) and aged (24-mo) intact, ovariectomized (OVX), or OVX + estrogen-treated (OVE) female Fischer 344 rats. Both aging and OVX reduced flow-induced NO production, whereas flow-induced H(2)O(2) production was not altered by age or estrogen status. Flow-induced vasodilation was evaluated before and after treatment with the superoxide dismutase (SOD) mimetic Tempol (100 μM) or the H(2)O(2) scavenger catalase (100 U/ml). Removal of H(2)O(2) with catalase reduced flow-induced dilation in all groups, whereas Tempol diminished vasodilation in intact and OVE, but not OVX, rats. Immunoblot analysis revealed elevated nitrotyrosine with aging and OVX. In young rats, OVX reduced SOD protein while OVE increased SOD in aged rats; catalase protein did not differ in any group. Collectively, these studies suggest that O(2)(-) and H(2)O(2) are critical components of flow-induced vasodilation in coronary arterioles from female rats; however, a chronic deficiency of O(2)(-) buffering by SOD contributes to impaired flow-induced dilation with aging and loss of estrogen. Furthermore, these data indicate that estrogen replacement restores O(2)(-) homeostasis and flow-induced dilation of coronary arterioles, even at an advanced age.

  10. OSU-03012, a novel celecoxib derivative, induces reactive oxygen species-related autophagy in hepatocellular carcinoma.

    PubMed

    Gao, Ming; Yeh, Pei Yen; Lu, Yen-Shen; Hsu, Chih-Hung; Chen, Kuen-Feng; Lee, Wei-Chung; Feng, Wen-Chi; Chen, Ching-Shih; Kuo, Min-Liang; Cheng, Ann-Lii

    2008-11-15

    Hepatocellular carcinoma (HCC) is the fifth most common cancer and the third leading cause of cancer death worldwide. Systemic treatments for HCC have been largely unsuccessful. OSU-03012 is a derivative of celecoxib with anticancer activity. The mechanism of action is presumably 3-phosphoinositide-dependent kinase 1 (PDK1) inhibition. This study investigated the potential of OSU-03012 as a treatment for HCC. OSU-03012 inhibited cell growth of Huh7, Hep3B, and HepG2 cells with IC(50) below 1 mumol/L. In Huh7 cells, OSU-03012 did not suppress PDK1 or AKT activity. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay and flow cytometry analysis indicated that OSU-03012 did not induce cellular apoptosis. Instead, morphologic studies by light and electron microscopy, as well as special biological staining with monodansylcadaverine, acridine orange, and microtubule-associated protein 1 light chain 3, revealed OSU-03012-induced autophagy of Huh7 cells. This OSU-03012-induced autophagy was inhibited by 3-methyladenine. Moreover, reactive oxygen species (ROS) accumulation was detected after OSU-03012 treatment. Blocking ROS accumulation with ROS scavengers inhibited autophagy formation, indicating that ROS accumulation and subsequent autophagy formation might be a major mechanism of action of OSU-03012. Daily oral treatment of BALB/c nude mice with OSU-03012 suppressed the growth of Huh7 tumor xenografts. Electron microscopic observation indicated that OSU-03012 induced autophagy in vivo. Together, our results show that OSU-03012 induces autophagic cell death but not apoptosis in HCC and that the autophagy-inducing activity is at least partially related to ROS accumulation.

  11. Measurements of UV-generated free radicals/reactive oxygen species (ROS) in skin

    NASA Astrophysics Data System (ADS)

    Herrling, Th.; Jung, K.; Fuchs, J.

    2006-03-01

    Free radicals/reactive oxygen species (ROS) generated in skin by UV irradiation were measured by electron spin resonance (ESR). To increase the sensitivity of measurement the short life free radicals/ROS were scavenged and accumulated by using the nitroxyl probe 3-carboxy-2,2,5,5-tetrametylpyrrolidine-1-oxyl (PCA). The spatial distribution of free radicals/ROS measured in pig skin biopsies with ESR imaging after UV irradiation corresponds to the intensity decay of irradiance in the depth of the skin. The main part of free radicals/ROS were generated by UVA (320-400 nm) so that the spatial distribution of free radicals reaches up to the lower side of the dermis. In vivo measurements on human skin were performed with a L-band ESR spectrometer and a surface coil integrating the signal intensities from all skin layers to get a sufficient signal amplitude. Using this experimental arrangement the protection of UVB and UVA/B filter against the generation of free radicals/ROS in skin were measured. The protection against ROS and the repair of damages caused by them can be realized with active antioxidants characterized by a high antioxidative power (AP). The effect of UV filter and antioxidants corresponding to their protection against free radicals/ROS in skin generated by UVAB irradiation can be quantified by the new radical sun protection factor (RSF). The RSF indicates the increase of time for staying in the sun to generate the same number of free radicals/ROS in the skin like for the unprotected skin. Regarding the amount of generated free radicals/ROS in skin as an biophysical endpoint the RSF characterizes both the protection against UVB and UVA radiation.

  12. Inhibition of myeloid cell differentiation in cancer: the role of reactive oxygen species.

    PubMed

    Kusmartsev, Sergei; Gabrilovich, Dmitry I

    2003-08-01

    It is well established that tumor growth is associated with accumulation of immature myeloid cells (ImC). They play an important role in tumor-associated immune suppression. ImC accumulate not only in tumor-bearing hosts but also in immunized, tumor-free hosts or hosts infected with bacterial pathogens. The kinetics of ImC in these mice is different. If in tumor-bearing mice, the number of ImC continues to increase with tumor progression in tumor-free mice after an initial spike, it decreases to the control level. Here, we have investigated the mechanisms of ImC accumulation in tumor-bearing hosts by comparing differentiation of ImC obtained from tumor-free and tumor-bearing mice. In the presence of appropriate growth factors, ImC isolated from tumor-free mice quickly differentiated in vitro into mature dendritic cells (DC), macrophages, and granulocytes. In contrast, differentiation of ImC from tumor-bearing mice was significantly delayed. Similar results were obtained in vivo after adoptive transfer of ImC into naïve, congeneic mice. ImC transferred into tumor-bearing recipients failed to differentiate into DC or macrophages. ImC from tumor-bearing mice had significantly higher levels of reactive oxygen species (ROS) than ImC obtained from tumor-free mice. Hydrogen peroxide (H(2)O(2)) but not superoxide radical anions was found to be the major part of this increased ROS production. In vitro experiments demonstrated that scavenging of H(2)O(2) with catalase induced differentiation of ImC from tumor-bearing mice into macrophages. Thus, this is a first demonstration that tumors may prevent differentiation of antigen-presenting cells by increasing the level of endogenous H(2)O(2) in immature myeloid cells.

  13. Reactive Oxygen Species Stimulate Insulin Secretion in Rat Pancreatic Islets: Studies Using Mono-Oleoyl-Glycerol

    PubMed Central

    Kane, Ada; Shirihai, Orian; Corkey, Barbara E.; Deeney, Jude T.

    2012-01-01

    Chronic exposure (24–72 hrs) of pancreatic islets to elevated glucose and fatty acid leads to glucolipoxicity characterized by basal insulin hypersecretion and impaired glucose-stimulated insulin secretion (GSIS). Our aim was to determine the mechanism for basal hypersecretion of insulin. We used mono-oleoyl-glycerol (MOG) as a tool to rapidly increase lipids in isolated rat pancreatic ß-cells and in the clonal pancreatic ß-cell line INS-1 832/13. MOG (25–400 µM) stimulated basal insulin secretion from ß-cells in a concentration dependent manner without increasing intracellular Ca2+ or O2 consumption. Like GSIS, MOG increased NAD(P)H and reactive oxygen species (ROS). The mitochondrial reductant ß-hydroxybutyrate (ß-OHB) also increased the redox state and ROS production, while ROS scavengers abrogated secretion. Diazoxide (0.4 mM) did not prevent the stimulatory effect of MOG, confirming that the effect was independent of the KATP-dependent pathway of secretion. MOG was metabolized to glycerol and long-chain acyl-CoA (LC-CoA), whereas, acute oleate did not similarly increase LC-CoA. Inhibition of diacylglycerol kinase (DGK) did not mimic the effect of MOG on insulin secretion, indicating that MOG did not act primarily by inhibiting DGK. Inhibition of acyl-CoA synthetase (ACS) reduced the stimulatory effect of MOG on basal insulin secretion by 30% indicating a role for LC-CoA. These data suggest that basal insulin secretion is stimulated by increased ROS production, due to an increase in the mitochondrial redox state independent of the established components of GSIS. PMID:22272304

  14. IGF-I enhances cellular senescence via the reactive oxygen species-p53 pathway

    SciTech Connect

    Handayaningsih, Anastasia-Evi; Takahashi, Michiko; Fukuoka, Hidenori; Iguchi, Genzo; Nishizawa, Hitoshi; Yamamoto, Masaaki; Suda, Kentaro; Takahashi, Yutaka

    2012-08-24

    Highlights: Black-Right-Pointing-Pointer Cellular senescence plays an important role in tumorigenesis and aging process. Black-Right-Pointing-Pointer We demonstrated IGF-I enhanced cellular senescence in primary confluent cells. Black-Right-Pointing-Pointer IGF-I enhanced cellular senescence in the ROS and p53-dependent manner. Black-Right-Pointing-Pointer These results may explain the underlying mechanisms of IGF-I involvement in tumorigenesis and in regulation of aging. -- Abstract: Cellular senescence is characterized by growth arrest, enlarged and flattened cell morphology, the expression of senescence-associated {beta}-galactosidase (SA-{beta}-gal), and by activation of tumor suppressor networks. Insulin-like growth factor-I (IGF-I) plays a critical role in cellular growth, proliferation, tumorigenesis, and regulation of aging. In the present study, we show that IGF-I enhances cellular senescence in mouse, rat, and human primary cells in the confluent state. IGF-I induced expression of a DNA damage marker, {gamma}H2AX, the increased levels of p53 and p21 proteins, and activated SA-{beta}-gal. In the confluent state, an altered downstream signaling of IGF-I receptor was observed. Treatment with a reactive oxygen species (ROS) scavenger, N-acetylcystein (NAC) significantly suppressed induction of these markers, indicating that ROS are involved in the induction of cellular senescence by IGF-I. In p53-null mouse embryonic fibroblasts, the IGF-I-induced augmentation of SA-{beta}-gal and p21 was inhibited, demonstrating that p53 is required for cellular senescence induced by IGF-I. Thus, these data reveal a novel pathway whereby IGF-I enhances cellular senescence in the ROS and p53-dependent manner and may explain the underlying mechanisms of IGF-I involvement in tumorigenesis and in regulation of aging.

  15. Reactive oxygen species promote heat shock protein 90-mediated HBV capsid assembly

    SciTech Connect

    Kim, Yoon Sik Seo, Hyun Wook Jung, Guhung

    2015-02-13

    Hepatitis B virus (HBV) infection induces reactive oxygen species (ROS) production and has been associated with the development of hepatocellular carcinoma (HCC). ROS are also an important factor in HCC because the accumulated ROS leads to abnormal cell proliferation and chromosome mutation. In oxidative stress, heat shock protein 90 (Hsp90) and glutathione (GSH) function as part of the defense mechanism. Hsp90 prevents cellular component from oxidative stress, and GSH acts as antioxidants scavenging ROS in the cell. However, it is not known whether molecules regulated by oxidative stress are involved in HBV capsid assembly. Based on the previous study that Hsp90 facilitates HBV capsid assembly, which is an important step for the packing of viral particles, here, we show that ROS enrich Hsp90-driven HBV capsid formation. In cell-free system, HBV capsid assembly was facilitated by ROS with Hsp90, whereas it was decreased without Hsp90. In addition, GSH inhibited the function of Hsp90 to decrease HBV capsid assembly. Consistent with the result of cell-free system, ROS and buthionine sulfoximine (BS), an inhibitor of GSH synthesis, increased HBV capsid formation in HepG2.2.15 cells. Thus, our study uncovers the interplay between ROS and Hsp90 during HBV capsid assembly. - Highlights: • We examined H{sub 2}O{sub 2} and GSH modulate HBV capsid assembly. • H{sub 2}O{sub 2} facilitates HBV capsid assembly in the presence of Hsp90. • GSH inhibits function of Hsp90 in facilitating HBV capsid assembly. • H{sub 2}O{sub 2} and GSH induce conformation change of Hsp90.

  16. The Defensive Role of Cumulus Cells Against Reactive Oxygen Species Insult in Metaphase II Mouse Oocytes.

    PubMed

    Shaeib, Faten; Khan, Sana N; Ali, Iyad; Thakur, Mili; Saed, Mohammed G; Dai, Jing; Awonuga, Awoniyi O; Banerjee, Jashoman; Abu-Soud, Husam M

    2016-04-01

    We investigated the ability of reactive oxygen species (ROS), such as hydrogen peroxide (H(2)O(2)), hydroxyl radical ((·)OH), and hypochlorous acid (HOCl), to overcome the defensive capacity of cumulus cells and elucidate the mechanism through which ROS differentially deteriorate oocyte quality. Metaphase II mouse oocytes with (n = 1634) and without cumulus cells (n = 1633) were treated with increasing concentration of ROS, and the deterioration in oocyte quality was assessed by the changes in the microtubule morphology and chromosomal alignment. Oocyte and cumulus cell viability and cumulus cell number were assessed by indirect immunofluorescence, staining of gap junction protein, and trypan blue staining. The treated oocytes showed decreased quality as a function of increasing concentrations of ROS when compared to controls. Cumulus cells show protection against H(2)O(2) and (·)OH insult at lower concentrations, but this protection was lost at higher concentrations (>50 μmol/L). At higher H(2)O(2) concentrations, treatment dramatically influenced the cumulus cell number and viability with resulting reduction in the antioxidant capacity making the oocyte more susceptible to oxidative damage. However, cumulus cells offered no significant protection against HOCl at any concentration used. In all circumstances in which cumulus cells did not offer protection to the oocyte, both cumulus cell number and viability were decreased. Therefore, the deterioration in oocyte quality may be caused by one or more of the following: a decrease in the antioxidant machinery by the loss of cumulus cells, the lack of scavengers for specific ROS, and/or the ability of the ROS to overcome these defenses.

  17. Reactive oxygen species induced by cold stratification promote germination of Hedysarum scoparium seeds.

    PubMed

    Su, Liqiang; Lan, Qinying; Pritchard, Hugh W; Xue, Hua; Wang, Xiaofeng

    2016-12-01

    Seed germination is comprehensively regulated by multiple intrinsic and extrinsic factors, and reactive oxygen species (ROS) are relatively new among these factors. However, the role and underlying mechanisms of ROS in germination regulation remain largely unknown. In this study, we initially found that cold stratification could promote germination and respiration of Hedysarum scoparium seeds, especially at low temperature. We then noted that a ROS environment change induced by hydrogen peroxide (H2O2) or methylviologen (MV) could similarly promote seed germination. On the other hand, the ROS scavenger N-acetyl-L-cysteine (NAC) suppressed germination of cold-stratified H. scoparium seeds, indicating a stimulatory role of ROS upon seed germination. An increased accumulation of O2(-) was detected in embryonic axes of cold-stratified seeds, and stratification-induced ROS generation as well as progressive accumulation of ROS during germination was further confirmed at the cellular level by confocal microscopy. Moreover, protein carbonylation in cold-stratified seeds was enhanced during germination, which was reversed by NAC treatment. Finally, the relationship between ROS and abscisic acid (ABA) or gibberellin (GA) in germination regulation was investigated. ABA treatment significantly inhibited germination and reduced the H2O2 content in both cold-stratified and non-cold-stratified seeds. Furthermore, we found that cold stratification mediates the down-regulation of the ABA content and increase of GA, suggesting an interaction between ROS and ABA/GA. These results in H. scoparium shed new light on the positive role of ROS and their cross-talk between plant hormones in seed germination.

  18. Reactive Oxygen Species Alter Autocrine and Paracrine Signaling

    SciTech Connect

    Zangar, Richard C.; Bollinger, Nikki; Weber, Thomas J.; Tan, Ruimin; Markillie, Lye Meng; Karin, Norman J.

    2011-12-01

    Cytochrome P450 (P450) 3A4 (CYP3A4) is the most abundant P450 protein in human liver and intestine and is highly inducible by a variety of drugs and other compounds. The P450 catalytic cycle is known to uncouple and release reactive oxygen species (ROS), but the effects of ROS from P450 and other enzymes in the endo-plasmic reticulum have been poorly studied from the perspective of effects on cell biology. In this study, we expressed low levels of CYP3A4 in HepG2 cells, a human hepatocarcinoma cell line, and examined effects on intracellular levels of ROS and on the secretion of a variety of growth factors that are important in extracellular communication. Using the redox-sensitive dye RedoxSensor red, we demonstrate that CYP3A4 expression increases levels of ROS in viable cells. A customELISA microarray platform was employed to demonstrate that expression of CYP3A4 increased secretion of amphiregulin, intracellular adhesion molecule 1, matrix metalloprotease 2, platelet-derived growth factor (PDGF), and vascular endothelial growth factor, but suppressed secretion of CD14. The antioxidant N-acetylcysteine suppressed all P450-dependent changes in protein secretion except for CD14. Quantitative RT-PCR demonstrated that changes in protein secretion were consistently associated with corresponding changes in gene expression. Inhibition of the NF-{kappa}B pathway blocked P450 effects on PDGF secretion. CYP3A4 expression also altered protein secretion in human mammary epithelial cells and C10 mouse lung cells. Overall, these results suggest that increased ROS production in the endoplasmic reticulum alters the secretion of proteins that have key roles in paracrine and autocrine signaling.

  19. Reactive oxygen species signaling in plants under abiotic stress.

    PubMed

    Choudhury, Shuvasish; Panda, Piyalee; Sahoo, Lingaraj; Panda, Sanjib Kumar

    2013-04-01

    Abiotic stresses like heavy metals, drought, salt, low temperature, etc. are the major factors that limit crop productivity and yield. These stresses are associated with production of certain deleterious chemical entities called reactive oxygen species (ROS), which include hydrogen peroxide (H₂O₂), superoxide radical (O₂(-)), hydroxyl radical (OH(-)), etc. ROS are capable of inducing cellular damage by degradation of proteins, inactivation of enzymes, alterations in the gene and interfere in various pathways of metabolic importance. Our understanding on ROS in response to abiotic stress is revolutionized with the advancements in plant molecular biology, where the basic understanding on chemical behavior of ROS is better understood. Understanding the molecular mechanisms involved in ROS generation and its potential role during abiotic stress is important to identify means by which plant growth and metabolism can be regulated under acute stress conditions. ROS mediated oxidative stress, which is the key to understand stress related toxicity have been widely studied in many plants and the results in those studies clearly revealed that oxidative stress is the main symptom of toxicity. Plants have their own antioxidant defense mechanisms to encounter ROS that is of enzymic and non-enzymic nature . Coordinated activities of these antioxidants regulate ROS detoxification and reduces oxidative load in plants. Though ROS are always regarded to impart negative impact on plants, some reports consider them to be important in regulating key cellular functions; however, such reports in plant are limited. Molecular approaches to understand ROS metabolism and signaling have opened new avenues to comprehend its critical role in abiotic stress. ROS also acts as secondary messenger that signals key cellular functions like cell proliferation, apoptosis and necrosis. In higher eukaryotes, ROS signaling is not fully understood. In this review we summarize our understanding on ROS

  20. Are mitochondrial reactive oxygen species required for autophagy?

    SciTech Connect

    Jiang, Jianfei; Maeda, Akihiro; Ji, Jing; Baty, Catherine J.; Watkins, Simon C.; Greenberger, Joel S.; Kagan, Valerian E.

    2011-08-19

    Highlights: {yields} Autophageal and apoptotic pathways were dissected in cytochrome c deficient cells. {yields} Staurosporine (STS)-induced autophagy was not accompanied by ROS generation. {yields} Autophagy was detectable in mitochondrial DNA deficient {rho}{sup 0} cells. {yields} Mitochondrial ROS are not required for the STS-induced autophagy in HeLa cells. -- Abstract: Reactive oxygen species (ROS) are said to participate in the autophagy signaling. Supporting evidence is obscured by interference of autophagy and apoptosis, whereby the latter heavily relies on ROS signaling. To dissect autophagy from apoptosis we knocked down expression of cytochrome c, the key component of mitochondria-dependent apoptosis, in HeLa cells using shRNA. In cytochrome c deficient HeLa1.2 cells, electron transport was compromised due to the lack of electron shuttle between mitochondrial respiratory complexes III and IV. A rapid and robust LC3-I/II conversion and mitochondria degradation were observed in HeLa1.2 cells treated with staurosporine (STS). Neither generation of superoxide nor accumulation of H{sub 2}O{sub 2} was detected in STS-treated HeLa1.2 cells. A membrane permeable antioxidant, PEG-SOD, plus catalase exerted no effect on STS-induced LC3-I/II conversion and mitochondria degradation. Further, STS caused autophagy in mitochondria DNA-deficient {rho}{sup o} HeLa1.2 cells in which both electron transport and ROS generation were completely disrupted. Counter to the widespread view, we conclude that mitochondrial ROS are not required for the induction of autophagy.

  1. Reactive Oxygen Species Tune Root Tropic Responses1[OPEN

    PubMed Central

    Krieger, Gat

    2016-01-01

    The default growth pattern of primary roots of land plants is directed by gravity. However, roots possess the ability to sense and respond directionally to other chemical and physical stimuli, separately and in combination. Therefore, these root tropic responses must be antagonistic to gravitropism. The role of reactive oxygen species (ROS) in gravitropism of maize and Arabidopsis (Arabidopsis thaliana) roots has been previously described. However, which cellular signals underlie the integration of the different environmental stimuli, which lead to an appropriate root tropic response, is currently unknown. In gravity-responding roots, we observed, by applying the ROS-sensitive fluorescent dye dihydrorhodamine-123 and confocal microscopy, a transient asymmetric ROS distribution, higher at the concave side of the root. The asymmetry, detected at the distal elongation zone, was built in the first 2 h of the gravitropic response and dissipated after another 2 h. In contrast, hydrotropically responding roots show no transient asymmetric distribution of ROS. Decreasing ROS levels by applying the antioxidant ascorbate, or the ROS-generation inhibitor diphenylene iodonium attenuated gravitropism while enhancing hydrotropism. Arabidopsis mutants deficient in Ascorbate Peroxidase 1 showed attenuated hydrotropic root bending. Mutants of the root-expressed NADPH oxidase RBOH C, but not rbohD, showed enhanced hydrotropism and less ROS in their roots apices (tested in tissue extracts with Amplex Red). Finally, hydrostimulation prior to gravistimulation attenuated the gravistimulated asymmetric ROS and auxin signals that are required for gravity-directed curvature. We suggest that ROS, presumably H2O2, function in tuning root tropic responses by promoting gravitropism and negatively regulating hydrotropism. PMID:27535793

  2. HIF and reactive oxygen species regulate oxidative phosphorylation in cancer.

    PubMed

    Hervouet, Eric; Cízková, Alena; Demont, Jocelyne; Vojtísková, Alena; Pecina, Petr; Franssen-van Hal, Nicole L W; Keijer, Jaap; Simonnet, Hélène; Ivánek, Robert; Kmoch, Stanislav; Godinot, Catherine; Houstek, Josef

    2008-08-01

    A decrease in oxidative phosphorylation (OXPHOS) is characteristic of many cancer types and, in particular, of clear cell renal carcinoma (CCRC) deficient in von Hippel-Lindau (vhl) gene. In the absence of functional pVHL, hypoxia-inducible factor (HIF) 1-alpha and HIF2-alpha subunits are stabilized, which induces the transcription of many genes including those involved in glycolysis and reactive oxygen species (ROS) metabolism. Transfection of these cells with vhl is known to restore HIF-alpha subunit degradation and to reduce glycolytic genes transcription. We show that such transfection with vhl of 786-0 CCRC (which are devoid of HIF1-alpha) also increased the content of respiratory chain subunits. However, the levels of most transcripts encoding OXPHOS subunits were not modified. Inhibition of HIF2-alpha synthesis by RNA interference in pVHL-deficient 786-0 CCRC also restored respiratory chain subunit content and clearly demonstrated a key role of HIF in OXPHOS regulation. In agreement with these observations, stabilization of HIF-alpha subunit by CoCl(2) decreased respiratory chain subunit levels in CCRC cells expressing pVHL. In addition, HIF stimulated ROS production and mitochondrial manganese superoxide dismutase content. OXPHOS subunit content was also decreased by added H(2)O(2.) Interestingly, desferrioxamine (DFO) that also stabilized HIF did not decrease respiratory chain subunit level. While CoCl(2) significantly stimulates ROS production, DFO is known to prevent hydroxyl radical production by inhibiting Fenton reactions. This indicates that the HIF-induced decrease in OXPHOS is at least in part mediated by hydroxyl radical production.

  3. Growth enhancement and gene expression of Arabidopsis thaliana irradiated with active oxygen species

    NASA Astrophysics Data System (ADS)

    Watanabe, Satoshi; Ono, Reoto; Hayashi, Nobuya; Shiratani, Masaharu; Tashiro, Kosuke; Kuhara, Satoru; Inoue, Asami; Yasuda, Kaori; Hagiwara, Hiroko

    2016-07-01

    The characteristics of plant growth enhancement effect and the mechanism of the enhancement induced by plasma irradiation are investigated using various active species in plasma. Active oxygen species in oxygen plasma are effective for growth enhancement of plants. DNA microarray analysis of Arabidopsis thaliana indicates that the genes coding proteins that counter oxidative stresses by eliminating active oxygen species are expressed at significantly high levels. The size of plant cells increases owing to oxygen plasma irradiation. The increases in gene expression levels and cell size suggest that the increase in the expression level of the expansin protein is essential for plant growth enhancement phenomena.

  4. Multiple free-radical scavenging (MULTIS) capacity in cattle serum

    PubMed Central

    Sueishi, Yoshimi; Kamogawa, Erisa; Kimura, Anna; Kitahara, Go; Satoh, Hiroyuki; Asanuma, Taketoshi; Oowada, Shigeru

    2017-01-01

    Multiple free-radical scavenging (MULTIS) activity in cattle and human sera was evaluated with electron spin resonance spectroscopy. Scavenging rates against six active species, namely hydroxyl radical, superoxide anion, alkoxyl radical, alkylperoxyl radical, methyl radical, and singlet oxygen were quantified. The difference in the electron spin resonance signal intensity in the presence and absence of the serum was converted into the scavenging rates. Comparative MULTIS measurements were made in sera from eight beef cattle, three fetal calves and fifteen healthy human volunteers. Further, we determined the MULTIS value of albumin, the most abundant component in serum. MULTIS values in cattle sera indicated higher scavenging activity against most free radical species tested than human sera. In particular, cattle serum scavenging activities against superoxide and methyl radical were higher than human serum by 2.6 and 3.7 fold, respectively. In cattle serum, albumin appears to play a dominant role in MULTIS activity, but in human serum that is not the case. Previous data indicated that the abundance of uric acid in bovine blood is nearly 80% less than humans; however, this difference does not explain the deviation in MULTIS profile. PMID:28163386

  5. Oxygen Pathway Modeling Estimates High Reactive Oxygen Species Production above the Highest Permanent Human Habitation

    PubMed Central

    Cano, Isaac; Selivanov, Vitaly; Gomez-Cabrero, David; Tegnér, Jesper; Roca, Josep; Wagner, Peter D.; Cascante, Marta

    2014-01-01

    The production of reactive oxygen species (ROS) from the inner mitochondrial membrane is one of many fundamental processes governing the balance between health and disease. It is well known that ROS are necessary signaling molecules in gene expression, yet when expressed at high levels, ROS may cause oxidative stress and cell damage. Both hypoxia and hyperoxia may alter ROS production by changing mitochondrial Po2 (). Because depends on the balance between O2 transport and utilization, we formulated an integrative mathematical model of O2 transport and utilization in skeletal muscle to predict conditions to cause abnormally high ROS generation. Simulations using data from healthy subjects during maximal exercise at sea level reveal little mitochondrial ROS production. However, altitude triggers high mitochondrial ROS production in muscle regions with high metabolic capacity but limited O2 delivery. This altitude roughly coincides with the highest location of permanent human habitation. Above 25,000 ft., more than 90% of exercising muscle is predicted to produce abnormally high levels of ROS, corresponding to the “death zone” in mountaineering. PMID:25375931

  6. Oxygen sensitivity of mitochondrial reactive oxygen species generation depends on metabolic conditions.

    PubMed

    Hoffman, David L; Brookes, Paul S

    2009-06-12

    The mitochondrial generation of reactive oxygen species (ROS) plays a central role in many cell signaling pathways, but debate still surrounds its regulation by factors, such as substrate availability, [O2] and metabolic state. Previously, we showed that in isolated mitochondria respiring on succinate, ROS generation was a hyperbolic function of [O2]. In the current study, we used a wide variety of substrates and inhibitors to probe the O2 sensitivity of mitochondrial ROS generation under different metabolic conditions. From such data, the apparent Km for O2 of putative ROS-generating sites within mitochondria was estimated as follows: 0.2, 0.9, 2.0, and 5.0 microM O2 for the complex I flavin site, complex I electron backflow, complex III QO site, and electron transfer flavoprotein quinone oxidoreductase of beta-oxidation, respectively. Differential effects of respiratory inhibitors on ROS generation were also observed at varying [O2]. Based on these data, we hypothesize that at physiological [O2], complex I is a significant source of ROS, whereas the electron transfer flavoprotein quinone oxidoreductase may only contribute to ROS generation at very high [O2]. Furthermore, we suggest that previous discrepancies in the assignment of effects of inhibitors on ROS may be due to differences in experimental [O2]. Finally, the data set (see supplemental material) may be useful in the mathematical modeling of mitochondrial metabolism.

  7. Surface Electrochemistry of Chloro(phthalocyaninato)rhodium(III) species, and Oxygen Reduction Electrocatalysis, Formation of a Dimeric Species

    DTIC Science & Technology

    1991-08-20

    rhodium(III) Species, and Oxygen Reduction Electrocatalysis , Formation of a Dimeric Species By Y.-H. Tse, P. Seymour, N. Kobayashi, H. Lam, C.C. Leznoff... Electrocatalysis , Formation of a Dimeric Species 12. PERSONAL AuTI𔃾OR(S)* Y.-H. Ise, P. Sey;mour, N. Kobayashi, H. Lam, C.C. Leznoff, and A.B.P. L...Oxygen Reduction Electrocatalysis . Formation of a Dimeric Species. Yu-Hong Tse, Penny Seymour, Nagao Kobayashi, 1 Herman Lam, Clifford C. Leznoff. and

  8. Upsides and Downsides of Reactive Oxygen Species for Cancer: The Roles of Reactive Oxygen Species in Tumorigenesis, Prevention, and Therapy

    PubMed Central

    Gupta, Subash C.; Hevia, David; Patchva, Sridevi; Park, Byoungduck; Koh, Wonil

    2012-01-01

    Abstract Significance: Extensive research during the last quarter century has revealed that reactive oxygen species (ROS) produced in the body, primarily by the mitochondria, play a major role in various cell-signaling pathways. Most risk factors associated with chronic diseases (e.g., cancer), such as stress, tobacco, environmental pollutants, radiation, viral infection, diet, and bacterial infection, interact with cells through the generation of ROS. Recent Advances: ROS, in turn, activate various transcription factors (e.g., nuclear factor kappa-light-chain-enhancer of activated B cells [NF-κB], activator protein-1, hypoxia-inducible factor-1α, and signal transducer and activator of transcription 3), resulting in the expression of proteins that control inflammation, cellular transformation, tumor cell survival, tumor cell proliferation and invasion, angiogenesis, and metastasis. Paradoxically, ROS also control the expression of various tumor suppressor genes (p53, Rb, and PTEN). Similarly, γ-radiation and various chemotherapeutic agents used to treat cancer mediate their effects through the production of ROS. Interestingly, ROS have also been implicated in the chemopreventive and anti-tumor action of nutraceuticals derived from fruits, vegetables, spices, and other natural products used in traditional medicine. Critical Issues: These statements suggest both “upside” (cancer-suppressing) and “downside” (cancer-promoting) actions of the ROS. Thus, similar to tumor necrosis factor-α, inflammation, and NF-κB, ROS act as a double-edged sword. This paradox provides a great challenge for researchers whose aim is to exploit ROS stress for the development of cancer therapies. Future Directions: The various mechanisms by which ROS mediate paradoxical effects are discussed in this article. The outstanding questions and future directions raised by our current understanding are discussed. Antioxid. Redox Signal. 16, 1295–1322. PMID:22117137

  9. Modeling the consequences of the demise and potential recovery of a keystone-species: wild rabbits and avian scavengers in Mediterranean landscapes.

    PubMed

    Cortés-Avizanda, Ainara; Colomer, Maria Àngels; Margalida, Antoni; Ceballos, Olga; Donázar, José Antonio

    2015-11-23

    Restoration of demised keystone-species populations is an overriding concern in conservation biology. However, since no population is independent of its environment, progress is needed in predicting the efficacy of restoration in unstable ecological contexts. Here, by means of Population Dynamics P-system Models (PDP), we studied long-term changes in the population size of Egyptian vultures (Neophron percnopterus) inhabiting a Natural Park, northern Spain, to changes in the numbers of wild rabbits (Oryctolagus cuniculus), a keystone-species of Mediterranean ecosystems that have suffered >90% population decline after a hemorrhagic disease outbreak. Low availability of rabbit carcasses leads Egyptian vultures to extend their foraging activities to unprotected areas with higher non-natural mortality whereas growing numbers of griffon vultures (Gyps fulvus), a dominant competitor, progressively monopolize trophic resources resulting in a focal population decrease. Modeling shows that, even if keystone-species populations recover in core protected areas, the return to the original studied population size may be unfeasible, due to both the high non-natural mortality rates in humanized areas and long-term changes in the scavenger guild structure. Policy decisions aimed to restore keystone-species should rely on holistic approaches integrating the effects of spatial heterogeneity on both producer and consumer populations as well as within-guild processes.

  10. Modeling the consequences of the demise and potential recovery of a keystone-species: wild rabbits and avian scavengers in Mediterranean landscapes

    PubMed Central

    Cortés-Avizanda, Ainara; Colomer, Maria Àngels; Margalida, Antoni; Ceballos, Olga; Donázar, José Antonio

    2015-01-01

    Restoration of demised keystone-species populations is an overriding concern in conservation biology. However, since no population is independent of its environment, progress is needed in predicting the efficacy of restoration in unstable ecological contexts. Here, by means of Population Dynamics P-system Models (PDP), we studied long-term changes in the population size of Egyptian vultures (Neophron percnopterus) inhabiting a Natural Park, northern Spain, to changes in the numbers of wild rabbits (Oryctolagus cuniculus), a keystone-species of Mediterranean ecosystems that have suffered >90% population decline after a hemorrhagic disease outbreak. Low availability of rabbit carcasses leads Egyptian vultures to extend their foraging activities to unprotected areas with higher non-natural mortality whereas growing numbers of griffon vultures (Gyps fulvus), a dominant competitor, progressively monopolize trophic resources resulting in a focal population decrease. Modeling shows that, even if keystone-species populations recover in core protected areas, the return to the original studied population size may be unfeasible, due to both the high non-natural mortality rates in humanized areas and long-term changes in the scavenger guild structure. Policy decisions aimed to restore keystone-species should rely on holistic approaches integrating the effects of spatial heterogeneity on both producer and consumer populations as well as within-guild processes. PMID:26593338

  11. Modeling the consequences of the demise and potential recovery of a keystone-species: wild rabbits and avian scavengers in Mediterranean landscapes

    NASA Astrophysics Data System (ADS)

    Cortés-Avizanda, Ainara; Colomer, Maria Àngels; Margalida, Antoni; Ceballos, Olga; Donázar, José Antonio

    2015-11-01

    Restoration of demised keystone-species populations is an overriding concern in conservation biology. However, since no population is independent of its environment, progress is needed in predicting the efficacy of restoration in unstable ecological contexts. Here, by means of Population Dynamics P-system Models (PDP), we studied long-term changes in the population size of Egyptian vultures (Neophron percnopterus) inhabiting a Natural Park, northern Spain, to changes in the numbers of wild rabbits (Oryctolagus cuniculus), a keystone-species of Mediterranean ecosystems that have suffered >90% population decline after a hemorrhagic disease outbreak. Low availability of rabbit carcasses leads Egyptian vultures to extend their foraging activities to unprotected areas with higher non-natural mortality whereas growing numbers of griffon vultures (Gyps fulvus), a dominant competitor, progressively monopolize trophic resources resulting in a focal population decrease. Modeling shows that, even if keystone-species populations recover in core protected areas, the return to the original studied population size may be unfeasible, due to both the high non-natural mortality rates in humanized areas and long-term changes in the scavenger guild structure. Policy decisions aimed to restore keystone-species should rely on holistic approaches integrating the effects of spatial heterogeneity on both producer and consumer populations as well as within-guild processes.

  12. Active Oxygen Species Generator by Low Pressure Silent Discharge and its Application to Water Treatment

    NASA Astrophysics Data System (ADS)

    Tanaka, Masaaki; Ikeda, Akira; Tanimura, Yasuhiro; Ohta, Koji; Yoshiyasu, Hajimu

    We have proposed the new water treatment using the active oxygen species such as an atomic oxygen with the oxidation power that is stronger than ozone. Based on the results of simulations we designed the silent discharge type active oxygen generator with a water ejector, which is operated on the discharge conditions of low pressure of 6.6kPa. and high temperature of about 200°C. The experimental results are as follows. (1) The yield of the active oxygen increases with the increase of the discharge tube temperature and the decrease of the gas pressure. (2) The life time of active oxygen is tens msec. (3) The active oxygen oxidizes efficiently the formic acid compared with ozone. It is assumed from these results that the active oxygen species having a strong oxidation power is generated.

  13. Lycopene cyclase paralog CruP protects against reactive oxygen species in oxygenic photosynthetic organisms.

    PubMed

    Bradbury, Louis M T; Shumskaya, Maria; Tzfadia, Oren; Wu, Shi-Biao; Kennelly, Edward J; Wurtzel, Eleanore T

    2012-07-03

    In photosynthetic organisms, carotenoids serve essential roles in photosynthesis and photoprotection. A previous report designated CruP as a secondary lycopene cyclase involved in carotenoid biosynthesis [Maresca J, et al. (2007) Proc Natl Acad Sci USA 104:11784-11789]. However, we found that cruP KO or cruP overexpression plants do not exhibit correspondingly reduced or increased production of cyclized carotenoids, which would be expected if CruP was a lycopene cyclase. Instead, we show that CruP aids in preventing accumulation of reactive oxygen species (ROS), thereby reducing accumulation of β-carotene-5,6-epoxide, a ROS-catalyzed autoxidation product, and inhibiting accumulation of anthocyanins, which are known chemical indicators of ROS. Plants with a nonfunctional cruP accumulate substantially higher levels of ROS and β-carotene-5,6-epoxide in green tissues. Plants overexpressing cruP show reduced levels of ROS, β-carotene-5,6-epoxide, and anthocyanins. The observed up-regulation of cruP transcripts under photoinhibitory and lipid peroxidation-inducing conditions, such as high light stress, cold stress, anoxia, and low levels of CO(2), fits with a role for CruP in mitigating the effects of ROS. Phylogenetic distribution of CruP in prokaryotes showed that the gene is only present in cyanobacteria that live in habitats characterized by large variation in temperature and inorganic carbon availability. Therefore, CruP represents a unique target for developing resilient plants and algae needed to supply food and biofuels in the face of global climate change.

  14. Atmospheric Hydrogen Scavenging: from Enzymes to Ecosystems

    PubMed Central

    Constant, Philippe; Hards, Kiel; Morales, Sergio E.; Oakeshott, John G.; Russell, Robyn J.; Taylor, Matthew C.; Berney, Michael; Conrad, Ralf; Cook, Gregory M.

    2014-01-01

    We have known for 40 years that soils can consume the trace amounts of molecular hydrogen (H2) found in the Earth's atmosphere. This process is predicted to be the most significant term in the global hydrogen cycle. However, the organisms and enzymes responsible for this process were only recently identified. Pure culture experiments demonstrated that several species of Actinobacteria, including streptomycetes and mycobacteria, can couple the oxidation of atmospheric H2 to the reduction of ambient O2. A combination of genetic, biochemical, and phenotypic studies suggest that these organisms primarily use this fuel source to sustain electron input into the respiratory chain during energy starvation. This process is mediated by a specialized enzyme, the group 5 [NiFe]-hydrogenase, which is unusual for its high affinity, oxygen insensitivity, and thermostability. Atmospheric hydrogen scavenging is a particularly dependable mode of energy generation, given both the ubiquity of the substrate and the stress tolerance of its catalyst. This minireview summarizes the recent progress in understanding how and why certain organisms scavenge atmospheric H2. In addition, it provides insight into the wider significance of hydrogen scavenging in global H2 cycling and soil microbial ecology. PMID:25501483

  15. Effect on active oxygen species of alliin and Allium sativum (garlic) powder.

    PubMed

    Kourounakis, P N; Rekka, E A

    1991-11-01

    Considering that oxygen toxicity and the related free radical attack are involved in many pathophysiological conditions, and that Allium sativum (ASP) has been used therapeutically for many of them since antiquity, we examined the intervention of ASP and alliin in free radical processes. It was found that ASP presented antioxidant activity and alliin was a very good hydroxyl radical scavenger. ASP presented good reducing ability, interacting with 1,1-diphenyl-2-picrylhydrazyl stable free radical (DPPH). These results indicate an involvement of the active Alluim sativum ingredients in free radical processes.

  16. Oxidation-extraction spectrometry of reactive oxygen species (ROS) generated by chlorophyllin magnesium (Chl-Mg) under ultrasonic irradiation.

    PubMed

    Guo, Yuwei; Cheng, Chunping; Wang, Jun; Jin, Xudong; Liu, Bin; Wang, Zhiqiu; Gao, Jingqun; Kang, Pingli

    2011-09-01

    In order to examine the mechanism and process of sonodynamic reaction, the chlorophyllin magnesium (Chl-Mg) acting as a sonosensitizer was irradiated by ultrasound, and the generation of reactive oxygen species (ROS) were detected by the method of oxidation-extraction spectrometry (OES). That is, under ultrasonic irradiation in the presence of Chl-Mg, the 1,5-diphenyl carbazide (DPCI) is oxidized by generated ROS into 1,5-diphenyl carbazone (DPCO), which can be extracted by mixed organic solvent and display a obvious visible absorption at 563 nm wavelength. Besides, the generation conditions of ROS were also reviewed. The results demonstrated that the quantities of generated ROS increased with the increase of ultrasonic irradiation time, Chl-Mg concentration and DPCI concentration. Finally, several radical scavengers (l-Histidine (His), 2,6-Di-tert-butyl-methylphenol (BHT) and Vitamin C (VC)) were used to determine the kind of the generated ROS. It was found that at least the hydroxyl radical (OH) and singlet oxygen (1O2) were generated in the presence of Chl-Mg under ultrasonic irradiation. It is wish that this paper might offer some valuable references for the study on the mechanism of SDT and the application of Chl-Mg in tumor treatment.

  17. Oxidation-extraction spectrometry of reactive oxygen species (ROS) generated by chlorophyllin magnesium (Chl-Mg) under ultrasonic irradiation

    NASA Astrophysics Data System (ADS)

    Guo, Yuwei; Cheng, Chunping; Wang, Jun; Jin, Xudong; Liu, Bin; Wang, Zhiqiu; Gao, Jingqun; Kang, Pingli

    2011-09-01

    In order to examine the mechanism and process of sonodynamic reaction, the chlorophyllin magnesium (Chl-Mg) acting as a sonosensitizer was irradiated by ultrasound, and the generation of reactive oxygen species (ROS) were detected by the method of oxidation-extraction spectrometry (OES). That is, under ultrasonic irradiation in the presence of Chl-Mg, the 1,5-diphenyl carbazide (DPCI) is oxidized by generated ROS into 1,5-diphenyl carbazone (DPCO), which can be extracted by mixed organic solvent and display a obvious visible absorption at 563 nm wavelength. Besides, the generation conditions of ROS were also reviewed. The results demonstrated that the quantities of generated ROS increased with the increase of ultrasonic irradiation time, Chl-Mg concentration and DPCI concentration. Finally, several radical scavengers (l-Histidine (His), 2,6-Di-tert-butyl-methylphenol (BHT) and Vitamin C (VC)) were used to determine the kind of the generated ROS. It was found that at least the hydroxyl radical (OH) and singlet oxygen ( 1O 2) were generated in the presence of Chl-Mg under ultrasonic irradiation. It is wish that this paper might offer some valuable references for the study on the mechanism of SDT and the application of Chl-Mg in tumor treatment.

  18. Heavy-metal-induced reactive oxygen species: phytotoxicity and physicochemical changes in plants.

    PubMed

    Shahid, Muhammad; Pourrut, Bertrand; Dumat, Camille; Nadeem, Muhammad; Aslam, Muhammad; Pinelli, Eric

    2014-01-01

    As a result of the industrial revolution, anthropogenic activities have enhanced there distribution of many toxic heavy metals from the earth's crust to different environmental compartments. Environmental pollution by toxic heavy metals is increasing worldwide, and poses a rising threat to both the environment and to human health.Plants are exposed to heavy metals from various sources: mining and refining of ores, fertilizer and pesticide applications, battery chemicals, disposal of solid wastes(including sewage sludge), irrigation with wastewater, vehicular exhaust emissions and adjacent industrial activity.Heavy metals induce various morphological, physiological, and biochemical dysfunctions in plants, either directly or indirectly, and cause various damaging effects. The most frequently documented and earliest consequence of heavy metal toxicity in plants cells is the overproduction of ROS. Unlike redox-active metals such as iron and copper, heavy metals (e.g, Pb, Cd, Ni, AI, Mn and Zn) cannot generate ROS directly by participating in biological redox reactions such as Haber Weiss/Fenton reactions. However, these metals induce ROS generation via different indirect mechanisms, such as stimulating the activity of NADPH oxidases, displacing essential cations from specific binding sites of enzymes and inhibiting enzymatic activities from their affinity for -SH groups on the enzyme.Under normal conditions, ROS play several essential roles in regulating the expression of different genes. Reactive oxygen species control numerous processes like the cell cycle, plant growth, abiotic stress responses, systemic signalling, programmed cell death, pathogen defence and development. Enhanced generation of these species from heavy metal toxicity deteriorates the intrinsic antioxidant defense system of cells, and causes oxidative stress. Cells with oxidative stress display various chemical,biological and physiological toxic symptoms as a result of the interaction between ROS and

  19. Reactive oxygen species cause direct damage of Engelbreth-Holm-Swarm matrix.

    PubMed Central

    Riedle, B.; Kerjaschki, D.

    1997-01-01

    Reactive oxygen species (ROS) are produced and released into the extracellular spaces in numerous diseases and contribute to development and progression, for example, of inflammatory diseases, proteinuria, and tumor invasion. However, little is known about ROS-induced chemical changes of interstitial matrix proteins and their consequences for the integrity of the matrix meshwork. As basement membranes and other matrices are highly cross-linked and complex, the relatively simple matrix produced by Engelbreth-Holm-Swarm (EHS) sarcoma, and proteins isolated therefrom, were incubated in vitro with defined concentrations of ROS that were generated by the Fenton or xanthine oxidase/xanthine reactions. This resulted in two counter-current effects. Although up to approximately 15% of the EHS matrix proteins were released into the supernatant in a ROS dose-response relationship, the residual insoluble matrix was partially cross-linked by ROS. Matrix proteins released into the supernatants were examined by rotary shadowing, quantitative sodium dodecyl sulfate polyacrylamide gel electrophoresis, immunoblotting, and fluorospectrometry for loss of tryptophans and formation of bityrosine residues. At relatively low ROS concentrations, selective liberation of morphologically intact laminin/entactin was found that, however, failed to reassociate and showed oxidative damage of its tryptophan residues. At higher ROS concentrations, laminin and entactin were progressively disintegrated, partially fragmented, and eventually completely degraded. At this point oligomers of type IV collagen predominated in the supernatant, and proteoglycans were not encountered at any concentration of ROS. Similar gradual molecular changes were also obtained when fractions of isolated soluble EHS matrix proteins were incubated with graded concentrations of ROS. In these experiments, the formation of covalently linked oligomers and aggregates paralleled the ROS-dependent formation of cross

  20. Reactive oxygen species controllable non-thermal helium plasmas for evaluation of plasmid DNA strand breaks

    NASA Astrophysics Data System (ADS)

    Young Kim, Jae; Lee, Dong-Hoon; Ballato, John; Cao, Weiguo; Kim, Sung-O.

    2012-11-01

    Non-thermal, oxygen-rich helium plasmas were investigated to achieve an enhanced reactive oxygen species concentration at low voltage driving conditions. A non-thermal plasma device was fabricated based on a theta-shaped tube, and its potential was investigated for use in topological alteration of plasmid DNA. The optical emission spectra of the plasma showed that the oxygen flow affected the plasma properties, even though an oxygen plasma was not produced. The plasmid DNA strand breaks became more significant with the addition of oxygen flow to the helium in a single hollow, theta-shaped tube with other experimental conditions being unchanged.

  1. The fate of cetacean carcasses in the deep sea: observations on consumption rates and succession of scavenging species in the abyssal north-east Atlantic Ocean

    PubMed Central

    Jones, E. G.; Collins, M. A.; Bagley, P. M.; Addison, S.; Priede, I. G.

    1998-01-01

    The fate of cetacean carcasses in the deep sea was investigated using autonomous deep-sea lander vehicles incorporating time-lapse camera systems, fish and amphipod traps. Three lander deployments placed cetacean carcasses at depths of 4000 to 4800 m in the north-east Atlantic for periods of 36 h, 152 h and 276 h before being recovered. The photographic sequences revealed that carcasses were rapidly consumed by fish and invertebrate scavengers with removal rates ranging from 0.05 to 0.4 kg h-1. In the longest experiment the carcass was skeletonized within five days. In each deployment, approximately an hour after emplacement, the grenadier Coryphaenoides (Nematonurus) armatus and large numbers of lysianassid amphipods had arrived at the food-fall. The initially high numbers of grenadiers declined once the majority of the bait had been consumed and a variety of other fish and invertebrates were then observed, some taking up residence at the site. None of the fish species appeared to consume the carcass directly, but preyed upon amphipods instead. Funnel traps recovered with the carcass indicated a succession in the species composition of amphipods, with the specialist necrophages such as Paralicella spp. being replaced by more generalist feeders of the Orchomene species complex.

  2. Genotoxicity of volatile and secondary reactive oxygen species generated by photosensitization

    SciTech Connect

    Camoirano, A.; De Flora, S.; Dahl, T.A. Tufts Univ. Veterinary, Boston, MA )

    1993-01-01

    Reactive oxygen species were generated in the gas phase by photosensitization involving illumination of Rose Bengal. Depending on whether the chromophore is dry or solubilized, this system produces either energy-transfer reactions leading to generation of singlet oxygen specifically, or a combination of energy-transfer and electron-transfer reactions, providing both singlet oxygen and reduced forms of oxygen, such as superoxide anion and hydrogen peroxide. In neither case were the reactive species mutagenic in strain TA104 of Salmonella typhimurium, which had been previously shown to be reverted by oxygen species generated by the hypoxanthine-xanthine oxidase system in aqueous medium. However, mixed oxygen species induced an increased lethality in a variety of DNA repair-deficient Escherichia coli strains. This genotoxic effect, mainly reparable by the uvrA and recA mechanisms, was efficiently prevented by the thiol N-acetyl-L-cysteine. Singlet oxygen itself failed to exert direct genotoxic effects, although secondary reactants produced by its reaction with cell components enhanced lethality in some repair-deficient bacteria. Distance-dependence analyses provided measurements of the lifetimes of the oxygen species generated in the gas phase. 35 refs., 7 figs., 2 tabs.

  3. Reactive oxygen species scavenger N-acetyl cysteine reduces methamphetamine-induced hyperthermia without affecting motor activity in mice

    PubMed Central

    Sanchez-Alavez, Manuel; Bortell, Nikki; Galmozzi, Andrea; Conti, Bruno; Marcondes, Maria Cecilia G.

    2014-01-01

    Hyperthermia is a potentially lethal side effect of Methamphetamine (Meth) abuse, which involves the participation of peripheral thermogenic sites such as the Brown Adipose Tissue (BAT). In a previous study we found that the anti-oxidant N-acetyl cysteine (NAC) can prevent the high increase in temperature in a mouse model of Meth-hyperthermia. Here, we have further explored the ability of NAC to modulate Meth-induced hyperthermia in correlation with changes in BAT. We found that NAC treatment in controls causes hypothermia, and, when administered prior or upon the onset of Meth-induced hyperthermia, can ameliorate the temperature increase and preserve mitochondrial numbers and integrity, without affecting locomotor activity. This was different from Dantrolene, which decreased motor activity without affecting temperature. The effects of NAC were seen in spite of its inability to recover the decrease of mitochondrial superoxide induced in BAT by Meth. In addition, NAC did not prevent the Meth-induced decrease of BAT glutathione. Treatment with S-adenosyl-L-methionine, which improves glutathione activity, had an effect in ameliorating Meth-induced hyperthermia, but also modulated motor activity. This suggests a role for the remaining glutathione for controlling temperature. However, the mechanism by which NAC operates is independent of glutathione levels in BAT and specific to temperature. Our results show that, in spite of the absence of a clear mechanism of action, NAC is a pharmacological tool to examine the dissociation between Meth-induced hyperthermia and motor activity, and a drug of potential utility in treating the hyperthermia associated with Meth-abuse. PMID:26346736

  4. Possible involvement of reactive oxygen species scavenging enzymes in desiccation sensitivity of Antiaris toxicaria seeds and axes.

    PubMed

    Cheng, Hong-Yan; Song, Song-Quan

    2008-12-01

    The relationships among desiccation sensitivities of Antiaris toxicaria seeds and axes, changes in activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR) and dehydroascorbate reductase, (DHAR), production rate of superoxide radical (.O(2) (-)), and the contents of hydrogen peroxide (H(2)O(2)) and thiobarbituric acid (TBA)-reactive substance were studied. Desiccation tolerance of seeds and axes decreased with dehydration. Desiccation tolerance of axes was higher than that of seeds, and that of epicotyls was higher than radicles. Activities of SOD, CAT and DHAR of seeds increased during the initial phase of dehydration, and then decreased with further dehydration, whereas activities of APX and GR decreased with dehydration. These five enzyme activities of axes, however, increased during the initial phase of dehydration, and then decreased with further dehydration. The rate of superoxide radical production, and the contents of H(2)O(2) and TBA-reactive products of seeds and axes gradually increased with dehydration. These results show that the A. toxicaria seed is a typical recalcitrant seed. Loss of desiccation tolerance in seeds and axes was correlated with the increase in .O(2) (-) production rate, content of H(2)O(2) and TBA-reactive products, and the decline of antioxidant enzyme activities of seeds and axes.

  5. Melatonin Improved Anthocyanin Accumulation by Regulating Gene Expressions and Resulted in High Reactive Oxygen Species Scavenging Capacity in Cabbage

    PubMed Central

    Zhang, Na; Sun, Qianqian; Li, Hongfei; Li, Xingsheng; Cao, Yunyun; Zhang, Haijun; Li, Shuangtao; Zhang, Lei; Qi, Yan; Ren, Shuxin; Zhao, Bing; Guo, Yang-Dong

    2016-01-01

    In this work, we found, that exogenous melatonin pretreatment improved anthocyanin accumulation (1- to 2-fold) in cabbage. To verify the relationship with melatonin and anthocyanin, an Arabidopsis mutant, snat, which expresses a defective form of the melatonin biosynthesis enzyme SNAT (Serotonin N-acetyl transferase), was employed. Under cold conditions, the foliage of wild-type Arabidopsis exhibited a deeper red color than the snat mutant. This finding further proved, that exogenous melatonin treatment was able to affect anthocyanin accumulation. To gain a better understanding of how exogenous melatonin upregulates anthocyanin, we measured gene expression in cabbage samples treated with melatonin and untreated controls. We found that the transcript levels of anthocyanin biosynthetic genes were upregulated by melatonin treatment. Moreover, melatonin treatment increased the expression levels of the transcription factors MYB, bHLH, and WD40, which constitute the transcriptional activation complex responsible for coordinative regulation of anthocyanin biosynthetic genes. We found, that free radical generation was downregulated, whereas the osmotic adjustment and antioxidant capacities were upregulated in exogenous melatonin-treated cabbage plants. We concluded, that melatonin increases anthocyanin production and benefits cabbage growth. PMID:27047496

  6. Oxygen Radical Scavenger Activity, EPR, NMR, Molecular Mechanics and Extended-Hückel Molecular Orbital Investigation of the Bis(Piroxicam)Copper(II) Complex

    PubMed Central

    Pogni, Rebecca; Basosi, Riccardo; Donati, Alessandro; Rossi, Claudio; Sabadini, Luciano; Rollo, Libertario; Lorenzini, Sauro; Gelli, Renata; Marcolongo, Roberto

    1995-01-01

    The oxygen radical scavenger activity (ORSA) of [CuII(Pir)2] (HPir = Piroxicam = 4-hydroxy -2- methyl -N-2- pyridyl -2H- 1,2-benzothiazine -3- carboxamide 1,1-dioxide) was determined by chemiluminescence of samples obtained by mixing human neutrophils (from healthy subjects) and [CuII(Pir)2(DMF)2] (DMF = N,N -dimethylformammide) in DMSO/GLY/PBS (2:1:2, v/v) solution (DMSO = dimethylsulfoxide, GLY = 1,2,3-propantriol, PBS = Dulbecco’s buffer salt solution). The ratio of the residual radicals, for the HPir (1.02·10−4M) and [CuII(Pir)2(DMF)2] (1.08·10−5M)/HPir (8.01·10−−5M) systems was higher than 12 (not stimulated) [excess of piroxicam was added (Cu/Pir molar ratio ≈1:10) in order to have most of the metal complexed as bischelate]. In contrast, the ratio of residual radicals for the CuCl2 (1.00·10−5M) and [CuII(Pir)2(DMF)2] (1.08·10−5M)/Hpir (8.01·10−5M)system was 5. The [CuII(Pir)2] compound is therefore a stronger radical scavenger than either HPir or CuCl2. A molecular mechanics (MM) analysis of the gas phase structures of neutral HPir, its zwitterionic (HPir+-) and anionic (Pir-) forms, and some CuII-piroxicam complexes based on X-ray structures allowed calculation of force constants. The most stable structure for HPir has a ZZZ conformation similar to that found in the CuII (and CdII complexes) in the solid state as well as in the gas phase. The structure is stabilized by a strong H bond which involves the N(amide)-H and O(enolic) groups. The MM simulation for the [CuII(Pir)2(DMF)2] complex showed that two high repulsive intramolecular contacts exist between a pyridyl hydrogen atom of one Pir- molecule with the O donor of the other ligand. These interactions activate a transition toward a pseudo-tetrahedral geometry, in the case the apical ligands are removed. On refluxing a suspension of [CuII(Pir)2(DMF)2] in acetone a brown microcystalline solid with the Cu(Pir)2·0.5DMF stoichiometry was in fact prepared. 13C spin-lattice relaxation

  7. Free radical-scavenging activities of Homalium species--An endangered medicinal plant of Eastern Ghats of India.

    PubMed

    Mahapatra, Ajay Kumar; Pani, Sweta Smita; Sahoo, Atish Kumar

    2015-01-01

    Three species of the genus Homalium - e.g. Homalium nepalense, Homalium tomentosum and Homalium zeylanicum (Flacourtiaceae) - are recorded in India which are confined to the Eastern Ghat hill ranges. While H. zeylanicum is the IUCN red-listed medium-sized tree, the other two are endangered species of medicinal significance. The antioxidant potential of leaf and bark of the plants was evaluated through successive extraction methods by using hexane, chloroform, ethyl acetate and methanol. The extracts were subjected to in vitro assays as DPPH, hydroxyl, nitric oxide and superoxide along with its biochemical estimation. Amongst all, the ethyl acetate extracts of bark is found to be most potent compared with that of the leaves. H. nepalense has the highest amount of total phenolic and flavonoid contents followed by H. tomentosum and H. zeylanicum, respectively, and significant antioxidant behaviour.

  8. Serratia Secondary Metabolite Prodigiosin Inhibits Pseudomonas aeruginosa Biofilm Development by Producing Reactive Oxygen Species that Damage Biological Molecules

    PubMed Central

    Kimyon, Önder; Das, Theerthankar; Ibugo, Amaye I.; Kutty, Samuel K.; Ho, Kitty K.; Tebben, Jan; Kumar, Naresh; Manefield, Mike

    2016-01-01

    Prodigiosin is a heterocyclic bacterial secondary metabolite belonging to the class of tripyrrole compounds, synthesized by various types of bacteria including Serratia species. Prodigiosin has been the subject of intense research over the last decade for its ability to induce apoptosis in several cancer cell lines. Reports suggest that prodigiosin promotes oxidative damage to double-stranded DNA (dsDNA) in the presence of copper ions and consequently leads to inhibition of cell-cycle progression and cell death. However, prodigiosin has not been previously implicated in biofilm inhibition. In this study, the link between prodigiosin and biofilm inhibition through the production of redox active metabolites is presented. Our study showed that prodigiosin (500 μM) (extracted from Serratia marcescens culture) and a prodigiosin/copper(II) (100 μM each) complex have strong RNA and dsDNA cleaving properties while they have no pronounced effect on protein. Results support a role for oxidative damage to biomolecules by H2O2 and hydroxyl radical generation. Further, it was demonstrated that reactive oxygen species scavengers significantly reduced the DNA and RNA cleaving property of prodigiosin. P. aeruginosa cell surface hydrophobicity and biofilm integrity were significantly altered due to the cleavage of nucleic acids by prodigiosin or the prodigiosin/copper(II) complex. In addition, prodigiosin also facilitated the bactericidal activity. The ability of prodigiosinto cause nucleic acid degradation offers novel opportunities to interfere with extracellular DNA dependent bacterial biofilms. PMID:27446013

  9. TRPA1 activation leads to neurogenic vasodilatation: involvement of reactive oxygen nitrogen species in addition to CGRP and NO

    PubMed Central

    Aubdool, Aisah A; Kodji, Xenia; Abdul‐Kader, Nayaab; Heads, Richard; Fernandes, Elizabeth S; Bevan, Stuart

    2016-01-01

    Abstract Background and Purpose Transient receptor potential ankyrin‐1 (TRPA1) activation is known to mediate neurogenic vasodilatation. We investigated the mechanisms involved in TRPA1‐mediated peripheral vasodilatation in vivo using the TRPA1 agonist cinnamaldehyde. Experimental Approach Changes in vascular ear blood flow were measured in anaesthetized mice using laser Doppler flowmetry. Key Results Topical application of cinnamaldehyde to the mouse ear caused a significant increase in blood flow in the skin of anaesthetized wild‐type (WT) mice but not in TRPA1 knockout (KO) mice. Cinnamaldehyde‐induced vasodilatation was inhibited by the pharmacological blockade of the potent microvascular vasodilator neuropeptide CGRP and neuronal NOS‐derived NO pathways. Cinnamaldehyde‐mediated vasodilatation was significantly reduced by treatment with reactive oxygen nitrogen species (RONS) scavenger such as catalase and the SOD mimetic TEMPOL, supporting a role of RONS in the downstream vasodilator TRPA1‐mediated response. Co‐treatment with a non‐selective NOS inhibitor L‐NAME and antioxidant apocynin further inhibited the TRPA1‐mediated vasodilatation. Cinnamaldehyde treatment induced the generation of peroxynitrite that was blocked by the peroxynitrite scavenger FeTPPS and shown to be dependent on TRPA1, as reflected by an increase in protein tyrosine nitration in the skin of WT, but not in TRPA1 KO mice. Conclusion and Implications This study provides in vivo evidence that TRPA1‐induced vasodilatation mediated by cinnamaldehyde requires neuronal NOS‐derived NO, in addition to the traditional neuropeptide component. A novel role of peroxynitrite is revealed, which is generated downstream of TRPA1 activation by cinnamaldehyde. This mechanistic pathway underlying TRPA1‐mediated vasodilatation may be important in understanding the role of TRPA1 in pathophysiological situations. PMID:27189253

  10. Solar light-induced production of reactive oxygen species by single walled carbon nanotubes in water

    EPA Science Inventory

    Photosensitizing processes of engineered nanomaterials (ENMs) which include photo-induced production of reactive oxygen species (ROS) convert light energy into oxidizing chemical energy that mediates transformations of nanomaterials. The oxidative stress associated with ROS may p...

  11. COMPARATIVE ANALYSIS OF REACTIVE OXYGEN SPECIES IN HUMAN PLASMA AND BLOOD

    EPA Science Inventory

    Reactive oxygen species (ROS) are commonly associated with diseased states (including asthma, cardiovascular disease, cancer) infections, and exposure to various toxicants in humans. It is of interest in epidemiology studies to characterize the association of oxidative stress in...

  12. The Effect of Oxygen Potential on the Sulfide Capacity for Slags Containing Multivalent Species

    NASA Astrophysics Data System (ADS)

    Allertz, Carl; Selleby, Malin; Sichen, Du

    2016-10-01

    The dependence of sulfide capacity on the oxygen partial pressure for slags containing multivalent species was investigated experimentally using a slag containing vanadium oxide. Copper-slag equilibration experiments were carried out at 1873 K (1600 °C) in the approximate oxygen partial pressure range 10-15.4 to 10-9 atm. The sulfide capacity was found to be strongly dependent on the oxygen potential in this slag system, increasing with the oxygen partial pressure. The sulfide capacity changed by more than two orders of magnitude over the oxygen partial pressure range. The effect of changing oxygen partial pressure was found to be much greater than the effect of changing slag composition at a fixed oxygen partial pressure.

  13. Light-independent reactive oxygen species (ROS) formation through electron transfer from carboxylated single-walled carbon nanotubes in water.

    PubMed

    Hsieh, Hsin-Se; Wu, Renren; Jafvert, Chad T

    2014-10-07

    Promising developments in application of carbon nanotubes (CNTs) have raised concern regarding potential biological and environmental effects upon their inevitable release to the environment. Although some CNTs have been reported to generate reactive oxygen species (ROS) under light, limited information exists on ROS generation by these materials in the dark. In this study, generation of ROS was examined, initiated by electron transfer from biological electron donors through carboxylated single-walled carbon nanotubes (C-SWCNT) to molecular oxygen in water in the dark. In the presence of C-SWCNT, the oxidation of NADH (β-nicotinamide adenine dinucleotide, reduced form) and DTTre (DL-dithiothreitol, reduced form) was confirmed by light absorbance shifts (340 nm to 260 nm during oxidation of NADH to NAD(+), and increased light absorbance at 280 nm during oxidation of DTTre). Production of superoxide anion (O2(•-)) was detected by its selective reaction with a tetrazolium salt (NBT(2+)), forming a formazan product that is visible at 530 nm. A modified acid-quenched N,N-diethyl-p-phenylenediamine (DPD) assay was used to measure the accumulation of H2O2 in C-SWCNT suspensions containing O2 and NADH. In the same suspensions (i.e., containing C-SWCNT, NADH, and O2), pBR322 DNA plasmid was cleaved, although •OH was not detected when using •OH scavenging molecular probes. These results indicate that the oxidation of electron donors by C-SWCNT can be a light-independent source of ROS in water, and that electron shuttling through CNTs to molecular oxygen may be a potential mechanism for DNA damage by this specific CNT and potentially other carbon-based nanomaterials.

  14. Sinoporphyrin sodium, a novel sensitizer, triggers mitochondrial-dependent apoptosis in ECA-109 cells via production of reactive oxygen species

    PubMed Central

    Wang, Haiping; Wang, Xiaobing; Zhang, Shaoliang; Wang, Pan; Zhang, Kun; Liu, Quanhong

    2014-01-01

    Background Sonodynamic therapy (SDT) is a promising method that uses ultrasound to activate certain chemical sensitizers for the treatment of cancer. The purpose of this study was to investigate the sonoactivity of a novel sensitizer, sinoporphyrin sodium (DVDMS), and its sonotoxicity in an esophageal cancer (ECA-109) cell line. Methods The fluorescence intensity of DVDMS, hematoporphyrin, protoporphyrin IX, and Photofrin II was detected by fluorescence microscopy and flow cytometry. Generation of singlet oxygen was measured using a 1, 3-diphenylisobenzofuran experiment. A 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide assay was used to examine cell viability. Production of reactive oxygen species (ROS) and destabilization of the mitochondrial membrane potential were assessed by flow cytometry. Apoptosis was analyzed using Annexin-PE/7-amino-actinomycin D staining. Confocal microscopy was performed to assess mitochondrial damage and identify release of cytochrome C after treatment. Western blots were used to determine expression of oxidative stress-related and apoptosis-associated protein. Ultrastructural changes in the cell were studied by scanning electron microscopy. Results DVDMS showed higher autofluorescence intensity and singlet oxygen production efficiency compared with other photosensitizers in both cancerous and normal cells. Compared with hematoporphyrin, DVDMS-mediated SDT was more cytotoxic in ECA-109 cells. Abundant intracellular ROS was found in the SDT groups, and the cytotoxicity induced by SDT was effectively remitted by ROS scavengers. DVDMS located mainly to the mitochondria of ECA-109 cells, which were seriously damaged after exposure to SDT. Release of cytochrome C, an increased rate of apoptosis, and activated apoptosis protein were detected in the SDT group. In addition, relatively severe cell damage was observed on scanning electron microscopy after treatment with DVDMS and SDT. Conclusion These results suggest that DVDMS

  15. Species-Level Variability in Extracellular Production Rates of Reactive Oxygen Species by Diatoms

    PubMed Central

    Schneider, Robin J.; Roe, Kelly L.; Hansel, Colleen M.; Voelker, Bettina M.

    2016-01-01

    Biological production and decay of the reactive oxygen species (ROS) hydrogen peroxide (H2O2) and superoxide (O2-) likely have significant effects on the cycling of trace metals and carbon in marine systems. In this study, extracellular production rates of H2O2 and O2- were determined for five species of marine diatoms in the presence and absence of light. Production of both ROS was measured in parallel by suspending cells on filters and measuring the ROS downstream using chemiluminescence probes. In addition, the ability of these organisms to break down O2- and H2O2 was examined by measuring recovery of O2- and H2O2 added to the influent medium. O2- production rates ranged from undetectable to 7.3 × 10−16 mol cell−1 h−1, while H2O2 production rates ranged from undetectable to 3.4 × 10−16 mol cell−1 h−1. Results suggest that extracellular ROS production occurs through a variety of pathways even amongst organisms of the same genus. Thalassiosira spp. produced more O2- in light than dark, even when the organisms were killed, indicating that O2- is produced via a passive photochemical process on the cell surface. The ratio of H2O2 to O2- production rates was consistent with production of H2O2 solely through dismutation of O2- for T. oceanica, while T. pseudonana made much more H2O2 than O2-. T. weissflogii only produced H2O2 when stressed or killed. P. tricornutum cells did not make cell-associated ROS, but did secrete H2O2-producing substances into the growth medium. In all organisms, recovery rates for killed cultures (94–100% H2O2; 10–80% O2-) were consistently higher than those for live cultures (65–95% H2O2; 10–50% O2-). While recovery rates for killed cultures in H2O2 indicate that nearly all H2O2 was degraded by active cell processes, O2- decay appeared to occur via a combination of active and passive processes. Overall, this study shows that the rates and pathways for ROS production and decay vary greatly among diatom species, even

  16. Species-level variability in extracellular production rates of reactive oxygen species by diatoms

    NASA Astrophysics Data System (ADS)

    Schneider, Robin; Roe, Kelly; Hansel, Colleen; Voelker, Bettina

    2016-03-01

    Biological production and decay of the reactive oxygen species (ROS) hydrogen peroxide (H2O2) and superoxide (O2-) likely have significant effects on the cycling of trace metals and carbon in marine systems. In this study, extracellular production rates of H2O2 and O2- were determined for five species of marine diatoms in the presence and absence of light. Production of both ROS was measured in parallel by suspending cells on filters and measuring the ROS downstream using chemiluminescence probes. In addition, the ability of these organisms to break down O2- and H2O2 was examined by measuring recovery of O2- and H2O2 added to the influent medium. O2- production rates ranged from undetectable to 7.3 x 10-16 mol cell-1 hr-1, while H2O2 production rates ranged from undetectable to 3.4 x 10-16 mol cell-1 hr-1. Results suggest that extracellular ROS production occurs through a variety of pathways even amongst organisms of the same genus. Thalassiosira spp. produced more O2- in light than dark, even when the organisms were killed, indicating that O2- is produced via a passive photochemical process on the cell surface. The ratio of H2O¬2 to O2- production rates was consistent with production of H2O2 solely through dismutation of O2- for T. oceanica, while T. pseudonana made much more H2O2 than O2 . T. weissflogii only produced H2O2 when stressed or killed. P. tricornutum cells did not make cell-associated ROS, but did secrete H2O2-producing substances into the growth medium. In all organisms, recovery rates for killed cultures (94-100% H2O2; 10-80% O2-) were consistently higher than those for live cultures (65-95% H2O2; 10-50% O2-). While recovery rates for killed cultures in H2O2 indicate that nearly all H2O2 was degraded by active cell processes, O2- decay appeared to occur via a combination of active and passive processes. Overall, this study shows that the rates and pathways for ROS production and decay vary greatly among diatom species, even between those that are

  17. Characterization of the Oxygen Transmission Rate of Oak Wood Species Used in Cooperage.

    PubMed

    Del Alamo-Sanza, María; Cárcel, Luis Miguel; Nevares, Ignacio

    2017-01-25

    The oxygen that wine receives while aged in barrels is of interest because it defines the reactions that occur during aging and, therefore, the final properties of the wine. This study is intended to make up for the lack of information concerning the oxygen permeability of eight different woods of Quercus alba L. and Quercus petraea (Matt.) Liebl. commonly used. In addition, it shows how oxygen transfer evolves with the liquid contact time during testing under similar aging conditions to those in wine barrels. French oak woods permitted a higher oxygenation rate than American ones in all cases. A decrease in the oxygen entry caused by impregnation of the wood during the process was observed in all of the species studied. This process is determined by the thickness of the flooded wood layer containing free water, although differently in the two species, possibly due to the anatomical structure and the logging process for each.

  18. Marine species in ambient low-oxygen regions subject to double jeopardy impacts of climate change.

    PubMed

    Stortini, Christine H; Chabot, Denis; Shackell, Nancy L

    2016-10-18

    We have learned much about the impacts of warming on the productivity and distribution of marine organisms, but less about the impact of warming combined with other environmental stressors, including oxygen depletion. Also, the combined impact of multiple environmental stressors requires evaluation at the scales most relevant to resource managers. We use the Gulf of St. Lawrence, Canada, characterized by a large permanently hypoxic zone, as a case study. Species distribution models were used to predict the impact of multiple scenarios of warming and oxygen depletion on the local density of three commercially and ecologically important species. Substantial changes are projected within 20-40 years. A eurythermal depleted species already limited to shallow, oxygen-rich refuge habitat (Atlantic cod) may be relatively uninfluenced by oxygen depletion but increase in density within refuge areas with warming. A more stenothermal, deep-dwelling species (Greenland halibut) is projected to lose ~55% of its high-density areas under the combined impacts of warming and oxygen depletion. Another deep-dwelling, more eurythermal species (Northern shrimp) would lose ~4% of its high-density areas due to oxygen depletion alone, but these impacts may be buffered by warming, which may increase density by 8% in less hypoxic areas, but decrease density by ~20% in the warmest parts of the region. Due to local climate variability and extreme events, and that our models cannot project changes in species sensitivity to hypoxia with warming, our results should be considered conservative. We present an approach to effectively evaluate the individual and cumulative impacts of multiple environmental stressors on a species-by-species basis at the scales most relevant to managers. Our study may provide a basis for work in other low-oxygen regions and should contribute to a growing literature base in climate science, which will continue to be of support for resource managers as climate change

  19. Sensitivity of primary fibroblasts in culture to atmospheric oxygen does not correlate with species lifespan

    PubMed Central

    Patrick, Alison; Seluanov, Michael; Hwang, Chaewon; Tam, Jonathan; Khan, Tanya; Morgenstern, Ari; Wiener, Lauren; Vazquez, Juan M.; Zafar, Hiba; Wen, Robert; Muratkalyeva, Malika; Doerig, Katherine; Zagorulya, Maria; Cole, Lauren; Catalano, Sophia; Lobo Ladd, Aliny AB; Coppi, A. Augusto; Coşkun, Yüksel; Tian, Xiao; Ablaeva, Julia; Nevo, Eviatar; Gladyshev, Vadim N.; Zhang, Zhengdong D.; Vijg, Jan; Seluanov, Andrei; Gorbunova, Vera

    2016-01-01

    Differences in the way human and mouse fibroblasts experience senescence in culture had long puzzled researchers. While senescence of human cells is mediated by telomere shortening, Parrinello et al. demonstrated that senescence of mouse cells is caused by extreme oxygen sensitivity. It was hypothesized that the striking difference in oxygen sensitivity between mouse and human cells explains their different rates of aging. To test if this hypothesis is broadly applicable, we cultured cells from 16 rodent species with diverse lifespans in 3% and 21% oxygen and compared their growth rates. Unexpectedly, fibroblasts derived from laboratory mouse strains were the only cells demonstrating extreme sensitivity to oxygen. Cells from hamster, muskrat, woodchuck, capybara, blind mole rat, paca, squirrel, beaver, naked mole rat and wild-caught mice were mildly sensitive to oxygen, while cells from rat, gerbil, deer mouse, chipmunk, guinea pig and chinchilla showed no difference in the growth rate between 3% and 21% oxygen. We conclude that, although the growth of primary fibroblasts is generally improved by maintaining cells in 3% oxygen, the extreme oxygen sensitivity is a peculiarity of laboratory mouse strains, possibly related to their very long telomeres, and fibroblast oxygen sensitivity does not directly correlate with species' lifespan. PMID:27163160

  20. The Janus face of reactive oxygen species in resistance and susceptibility of plants to necrotrophic and biotrophic pathogens.

    PubMed

    Barna, B; Fodor, J; Harrach, B D; Pogány, M; Király, Z

    2012-10-01

    Plant pathogens can be divided into biotrophs and necrotrophs according to their different life styles; biotrophs prefer living, while necrotrophs prefer dead cells for nutritional purposes. Therefore tissue necrosis caused by reactive oxygen species (ROS) during pathogen infection increases host susceptibility to necrotrophic, but resistance to biotrophic pathogen. Consequently, elevation of antioxidant capacity of plants enhances their tolerance to development of necroses caused by necrotrophic pathogens. Plant hormones can strongly influence induction of ROS and antioxidants, thereby influencing susceptibility or resistance of plants to pathogens. Pathogen-induced ROS themselves are considered as signaling molecules. Generally, salicylic acid (SA) signaling induces defense against biotrophic pathogens, whereas jasmonic acid (JA) against necrotrophic pathogens. Furthermore pathogens can modify plant's defense signaling network for their own benefit by changing phytohormone homeostasis. On the other hand, ROS are harmful also to the pathogens, consequently they try to defend themselves by elevating antioxidant activity and secreting ROS scavengers in the infected tissue. The Janus face nature of ROS and plant cell death on biotrophic and on necrotrophic pathogens is also supported by the experiments with BAX inhibitor-1 and the mlo mutation of Mlo gene in barley. It was found that ROS and elevated plant antioxidant activity play an important role in systemic acquired resistance (SAR) and induced systemic resistance (ISR), as well as in mycorrhiza induced abiotic and biotic stress tolerance of plants.

  1. Reactive Oxygen Species Donors Increase the Responsiveness of Dorsal Horn Neurons and Induce Mechanical Hyperalgesia in Rats

    PubMed Central

    Kim, Hee Young; Lee, Inhyung; Chun, Sang Woo; Kim, Hee Kee

    2015-01-01

    Our previous studies suggest that reactive oxygen species (ROS) scavengers have analgesic effect on neuropathic pain through spinal mechanisms in the rat. The studies suggest that superoxide in spinal cord is one of important mediators of persistent pain. To test the hypothesis that increase of superoxide-derived intermediates leads to central sensitization and pain, the effects of an intrathecal injection of chemical ROS donors releasing either OH∙, OCl−, or H2O2 were examined on pain behaviors. Following treatment with t-BOOH (OH∙ donor), dorsal horn neuron responses to mechanical stimuli in normal rats and the changes of neuronal excitability were explored on substantia gelatinosa (SG) neurons using whole-cell patch clamping recordings. Intrathecal administration of t-BOOH or NaOCl (OCl− donor), but not H2O2, significantly decreased mechanical thresholds of hind paws. The responses of wide dynamic range neurons to mechanical stimuli increased after a local application of t-BOOH. The t-BOOH increased the frequency and the amplitude of excitatory postsynaptic potentials, depolarized membrane potential in SG neurons, and increased the frequency of action potentials evoked by depolarizing current pulses. These results suggest that elevated ROS, especially OH∙, in the spinal cord sensitized dorsal horn neurons and produced hyperalgesia in normal rats. PMID:26457204

  2. Involvement of Reactive Oxygen Species and Mitochondrial Proteins in Biophoton Emission in Roots of Soybean Plants under Flooding Stress.

    PubMed

    Kamal, Abu Hena Mostafa; Komatsu, Setsuko

    2015-05-01

    To understand the mechanism of biophoton emission, ROS and mitochondrial proteins were analyzed in soybean plants under flooding stress. Enzyme activity and biophoton emission were increased in the flooding stress samples when assayed in reaction mixes specific for antioxidant enzymes and reactive oxygen species; although the level of the hydroxyl radicals was increased at day 4 (2 days of flooding) compared to nonflooding at day 4, the emission of biophotons did not change. Mitochondria were isolated and purified from the roots of soybean plants grown under flooding stress by using a Percoll gradient, and proteins were analyzed by a gel-free proteomic technique. Out of the 98 mitochondrial proteins that significantly changed abundance under flooding stress, 47 increased and 51 decreased at day 4. The mitochondrial enzymes fumarase, glutathione-S-transferase, and aldehyde dehydrogenase increased at day 4 in protein abundance and enzyme activity. Enzyme activity and biophoton emission decreased at day 4 by the assay of lipoxygenase under stress. Aconitase, acyl CoA oxidase, succinate dehydrogenase, and NADH ubiquinone dehydrogenase were up-regulated at the transcription level. These results indicate that oxidation and peroxide scavenging might lead to biophoton emission and oxidative damage in the roots of soybean plants under flooding stress.

  3. An intracellular redox sensor for reactive oxygen species at the M3-M4 linker of GABAAρ1 receptors

    PubMed Central

    Beltrán González, Andrea N; Gasulla, Javier; Calvo, Daniel J

    2014-01-01

    Background and Purpose Reactive oxygen species (ROS) are normally involved in cell oxidative stress but also play a role as cellular messengers in redox signalling; for example, modulating the activity of neurotransmitter receptors and ion channels. However, the direct actions of ROS on GABAA receptors were not previously demonstrated. In the present work, we studied the effects of ROS on GABAAρ1 receptor function. Experimental Approach GABAAρ1 receptors were expressed in oocytes and GABA-evoked responses electrophysiologically recorded in the presence or absence of ROS. Chemical protection of cysteines by selective sulfhydryl reagents and site-directed mutagenesis studies were used to identify protein residues involved in ROS actions. Key Results GABAAρ1 receptor-mediated responses were significantly enhanced in a concentration-dependent and reversible manner by H2O2. Potentiating effects were attenuated by a free radical scavenger, lipoic acid or an inhibitor of the Fenton reaction, deferoxamine. Each ρ1 subunit contains only three cysteine residues, two extracellular at the Cys-loop (C177 and C191) and one intracellular (C364) at the M3-M4 linker. Mutant GABAAρ1 receptors in which C364 was exchanged by alanine were completely insensitive to modulation, implying that this site, rather than a cysteine in the Cys-loop, is essential for ROS modulation. Conclusion and Implications Our results show that the function of GABAAρ1 receptors is enhanced by ROS and that the intracellular C364 is the sensor for ROS actions. PMID:24428763

  4. Central Signaling Elements of Intercellular Reactive Oxygen/Nitrogen Species-dependent Induction of Apoptosis in Malignant Cells.

    PubMed

    Bauer, Georg

    2017-02-01

    Intercellular reactive oxygen/reactive nitrogen species-(ROS/RNS)-dependent induction of apoptosis in malignant cells is discussed as a potential control step during oncogenesis. In previous studies, the mechanism of intercellular apoptosis-inducing signaling was mainly established through the use of specific inhibitors and scavengers. Here, a detailed analysis was carried out based on small interfering ribonucleic acid (siRNA)-mediated knockdown of central players of intercellular ROS/RNS signaling and of the mitochondrial and the FAS receptor-dependent pathway of apoptosis. The data show that transforming growth factor β1, transforming growth factor β receptor, NADPH oxidase-1 (NOX1), NOX1 organizer, and NOX1 activator control the HOCl and the NO/peroxynitrite signaling pathways. Dual oxidase-1 (DUOX1) is specifically involved in HOCl signaling, and NO synthase in NO/peroxynitrite signaling. Both pathways utilize intracellular signal transduction through protein kinase C zeta, sphingomyelinase and central elements of the mitochondrial pathway of apoptosis, whereas the FAS receptor and FAS ligand do not seem to play a role.

  5. Biochemical effects of the flavanol-rich lychee fruit extract on the melanin biosynthesis and reactive oxygen species.

    PubMed

    Hagiwara, Kazuya; Okura, Masae; Sumikawa, Yasuyuki; Hida, Tokimasa; Kuno, Atsushi; Horio, Yoshiyuki; Yamashita, Toshiharu

    2016-10-01

    An ingredient of fruit polyphenol, resveratrol, is known to have an inhibitory effect on melanogenesis. In order to examine the functional differences between resveratrol and other fruit polyphenols, we compared biochemical effects of a resveratrol-free polyphenol, flavanol-rich lychee fruit extract (FRLFE), with other phenolic compounds including resveratrol. FRLFE as well as hydroquinone and resveratrol suppressed growth of B16F1 melanoma cells more significantly than rhododendrol or arbutin. Resveratrol suppressed mushroom tyrosinase at the lowest concentration (23.0 μmol/L) among the compounds tested. FRLFE and hydroquinone suppressed tyrosinase at almost the same concentration (half maximal inhibitory concentration [IC50 ], 83.5 and 94.6 μmol/L, respectively), which was higher than rhododendrol, ascorbic acid and arbutin (IC50 , 245, 345 and 421 μmol/L, respectively). Western blot analysis revealed that although resveratrol decreased expressions of tyrosinase and tyrosinase-related protein 1, FRLFE did not affect their expressions. Both FRLFE and resveratrol suppressed antimycin A-mediated reactive oxygen species (ROS) production in melanocytic cells. Resveratrol-mediated ROS suppression was inhibited by nicotinamide, a SIRT1 inhibitor. However, FRLFE-mediated suppression was not affected by nicotinamide. Moreover, FRLFE directly decreased superoxide in vitro, as detected by superoxide dismutase-like scavenging activity assay. These results suggest that FRLFE can protect melanocytes from cytotoxicity caused by an excess amount of melanin and ROS in a different manner from resveratrol.

  6. Salinomycin simultaneously induces apoptosis and autophagy through generation of reactive oxygen species in osteosarcoma U2OS cells.

    PubMed

    Kim, Sang-Hun; Choi, Young-Jun; Kim, Kwang-Youn; Yu, Sun-Nyoung; Seo, Young-Kyo; Chun, Sung-Sik; Noh, Kyung-Tae; Suh, Jeung-Tak; Ahn, Soon-Cheol

    2016-04-29

    Salinomycin, a polyether antibiotic, acts as a highly selective potassium ionophore. It was reported to anticancer activity on various cancer cell lines. In this study, salinomycin was examined on apoptosis and autophagy through generation of reactive oxygen species (ROS) in osteosarcoma U2OS cells. Apoptosis, autophagy, mitochondrial membrane potential (MMP) and ROS were analyzed using flow cytometry. Also, expressions of apoptosis- and autophagy-related proteins were determined by western blotting. As a result, salinomycin triggered apoptosis of U2OS cells, which was accompanied by change of MMP and cleavage of caspases-3 and poly (ADP-ribose) polymerase. And salinomycin increased the expression of autophagy-related protein and accumulation of acidic vesicular organelles (AVO). Salinomycin-induced ROS production promotes both apoptosis and autophagy, as evidenced by the result that treatment of N-acetyl-l-cysteine (NAC), a ROS scavenger, attenuated both apoptosis and autophagy. In addition, inhibition of autophagy by 3-methyladenine (3 MA) enhanced the salinoymcin-induced apoptosis. Taken together, these results suggested that salinomycin-induced autophagy, as a survival mechanism, might be a potential strategy through ROS regulation in cancer therapy.

  7. Pathogenesis of multiple organ dysfunction syndrome--endotoxin, inflammatory cells, and their mediators: cytokines and reactive oxygen species.

    PubMed

    Maier, R V

    2000-01-01

    Multiple organ dysfunction syndrome (MODS) is caused by an overwhelming, uncontrolled systemic inflammatory response that is activated by a number of hostile stimuli including sepsis, hypovolemic shock, and severe trauma resulting in massive tissue injury. The indiscriminate activation of the inflammatory response due to these insults causes loss of the host's ability to localize the inflammation to the focus of the problem, leading to systemic inflammation and severe host tissue damage and subsequent MODS. While the major players, namely neutrophils, macrophages, endotoxin, cytokines, and oxidants have been known for some time, the disease processes responsible for the pathogenesis of MODS have only recently been elucidated. Our newly found knowledge has resulted in the development of novel therapeutic strategies to prevent or treat MODS, such as scavenging toxic oxygen species and inhibiting endotoxin, or cytokine production, or cytokine activity. Unfortunately, these strategies have not resulted in improved mortality rates among patients with MODS. The complex nature of the host response to severe insults combined with the fact that the host has multiple, redundant parallel systems to deal with various insults has made it difficult for clinical interventions to adequately ameliorate the disease process among patients at risk for MODS. The purpose of this article is to attempt to "dissect out" several individual components of the inflammatory response that play important roles in the development of MODS and to review some potentially beneficial approaches to combat these harmful processes.

  8. Study on the generation mechanism of reactive oxygen species on calcium peroxide by chemiluminescence and UV-visible spectra.

    PubMed

    Ma, Yong; Zhang, Bo-Tao; Zhao, Lixia; Guo, Guangsheng; Lin, Jin-Ming

    2007-01-01

    In the present work, the generation mechanism of reactive oxygen species (ROS) on calcium peroxide (CaO(2)) was studied. A very intense chemiluminescence (CL) signal was observed when adding an aqueous solution of luminol or 2-methyl-6-(4-methoxyphenyl)-3,7-dihydroimidazo[1,2alpha]-pyrazin-3-one hydrochloride (MCLA) to a suspension of CaO(2). The ROS released on CaO(2) were thought to be oxidizing agents leading to CL, and were characterized by CL, UV-visible (UV-vis) spectra and the effective scavengers of the special ROS. From experimental results, the hydroxyl (.OH) and superoxide (.O(2) (-)) radicals were suggested to exist on the surface of CaO(2). A reaction scheme for the formation of the ROS on CaO(2) was also proposed and discussed. Of more interest was the finding that the CaO(2) which released the .OH and .O(2) (-) on the surface exhibited good transition properties compared with alkaline-earth metal peroxides of the same group (MgO(2), BaO(2)).

  9. The Interrelationship between Abscisic Acid and Reactive Oxygen Species Plays a Key Role in Barley Seed Dormancy and Germination

    PubMed Central

    Ishibashi, Yushi; Aoki, Nozomi; Kasa, Shinsuke; Sakamoto, Masatsugu; Kai, Kyohei; Tomokiyo, Reisa; Watabe, Gaku; Yuasa, Takashi; Iwaya-Inoue, Mari

    2017-01-01

    Seed dormancy is one of the adaptive responses in the plant life cycle and an important agronomic trait. Reactive oxygen species (ROS) release seed dormancy and promote seed germination in several cereal crops; however, the key regulatory mechanism of ROS-mediated seed dormancy and germination remains controversial. Here, we focused on the relationship between hydrogen peroxide (a ROS) and abscisic acid (ABA) in dormant and non-dormant barley seeds. The hydrogen peroxide (H2O2) level produced in barley seed embryos after imbibition was higher in non-dormant seeds than in dormant seeds. H2O2 regulated the ABA content in the embryos through ABA-8′-hydroxylase, an ABA catabolic enzyme. Moreover, compared with non-dormant seeds, in dormant seeds the activity of NADPH oxidase, which produces ROS, was lower, whereas the activity of catalase, which is a H2O2 scavenging enzyme, was higher, as was the expression of HvCAT2. Furthermore, precocious germination of isolated immature embryos was suppressed by the transient introduction of HvCAT2 driven by the maize (Zea mays) ubiquitin promoter. HvCAT2 expression was regulated through an ABA-responsive transcription factor (HvABI5) induced by ABA. These results suggest that the changing of balance between ABA and ROS is active in barley seed embryos after imbibition and regulates barley seed dormancy and germination. PMID:28377774

  10. Glibenclamide decreases ATP-induced intracellular calcium transient elevation via inhibiting reactive oxygen species and mitochondrial activity in macrophages.

    PubMed

    Li, Duo-ling; Ma, Zhi-yong; Fu, Zhi-jie; Ling, Ming-ying; Yan, Chuan-zhu; Zhang, Yun

    2014-01-01

    Increasing evidence has revealed that glibenclamide has a wide range of anti-inflammatory effects. However, it is unclear whether glibenclamide can affect the resting and adenosine triphosphate (ATP)-induced intracellular calcium ([Ca(2+)]i) handling in Raw 264.7 macrophages. In the present study, [Ca(2+)]i transient, reactive oxygen species (ROS) and mitochondrial activity were measured by the high-speed TILLvisION digital imaging system using the indicators of Fura 2-am, DCFDA and rhodamine-123, respectively. We found that glibenclamide, pinacidil and other unselective K(+) channel blockers had no effect on the resting [Ca(2+)]i of Raw 264.7 cells. Extracellular ATP (100 µM) induced [Ca(2+)]i transient elevation independent of extracellular Ca(2+). The transient elevation was inhibited by an ROS scavenger (tiron) and mitochondria inhibitor (rotenone). Glibenclamide and 5-hydroxydecanoate (5-HD) also decreased ATP-induced [Ca(2+)]i transient elevation, but pinacidil and other unselective K(+) channel blockers had no effect. Glibenclamide also decreased the peak of [Ca(2+)]i transient induced by extracellular thapsigargin (Tg, 1 µM). Furthermore, glibenclamide decreased intracellular ROS and mitochondrial activity. When pretreated with tiron and rotenone, glibenclamide could not decrease ATP, and Tg induced maximal [Ca(2+)]i transient further. We conclude that glibenclamide may inhibit ATP-induced [Ca(2+)]i transient elevation by blocking mitochondria KATP channels, resulting in decreased ROS generation and mitochondrial activity in Raw 264.7 macrophages.

  11. Dandelion (Taraxacum officinale) flower extract suppresses both reactive oxygen species and nitric oxide and prevents lipid oxidation in vitro.

    PubMed

    Hu, C; Kitts, D D

    2005-08-01

    Flavonoids and coumaric acid derivatives were identified from dandelion flower (Taraxacum officinale). Characteristics of chain-breaking antioxidants, such as extended lag phase and reduced propagation rate, were observed in oxidation of linoleic acid emulsion with the addition of dandelion flower extract (DFE). DFE suppressed both superoxide and hydroxyl radical, while the latter was further distinguished by both site-specific and non-specific hydroxyl radical inhibition. DPPH-radical-scavenging activity and a synergistic effect with alpha-tocopherol were attributed to the reducing activity derived from phenolic content of DFE. A significant (p < 0.05) and concentration-dependent, reduced nitric oxide production from acterial-lipopolysaccharide-stimulated mouse macrophage RAW264.7 cells was observed with the addition of DFE. Moreover, peroxyl-radical-induced intracellular oxidation of RAW264.7 cells was inhibited significantly (p < 0.05) by the addition of DFE over a range of concentrations. These results showed that the DFE possessed marked antioxidant activity in both biological and chemical models. Furthermore, the efficacy of DFE in inhibiting both reactive oxygen species and nitric oxide were attributed to its phenolic content.

  12. Disulfiram induces copper-dependent stimulation of reactive oxygen species and activation of the extrinsic apoptotic pathway in melanoma.

    PubMed

    Morrison, Brian W; Doudican, Nicole A; Patel, Kirtesh R; Orlow, Seth J

    2010-02-01

    Melanoma is the most aggressive and deadly form of skin cancer. The current standard of care produces response rates of less than 20%, underscoring the critical need for identification of new effective, nontoxic therapies. Disulfiram (DSF) was identified using a drug screen as one of the several compounds that preferentially decreased proliferation in multiple melanoma subtypes compared with benign melanocytes. DSF, a member of the dithiocarbamate family, is a copper (Cu) chelator, and Cu has been shown previously to enhance DSF-mediated growth inhibition and apoptosis in cancer cells. Here, we report that in the presence of free Cu, DSF inhibits cellular proliferation and induces apoptosis in a panel of cell lines representing primary and metastatic nodular and superficial spreading melanoma. Both decreased cellular proliferation and increased apoptosis were seen at 50-500 nmol/l DSF concentrations that are achievable through oral dosing of the medication. In the presence of Cu, DSF caused activation of the extrinsic pathway of apoptosis as measured by caspase-8 cleavage. The addition of Z-IETD-FMK, a selective caspase-8 inhibitor, was protective against DSF-Cu-induced apoptosis. Production of reactive oxygen species (ROS) in response to DSF-Cu treatment preceded the induction of apoptosis. Both ROS production and apoptosis were prevented by coincubation of N-acetyl cysteine, a free radical scavenger. Our study shows that DSF might be used to target both nodular and superficial spreading melanoma through ROS production and activation of the extrinsic pathway of apoptosis.

  13. Interconnections between apoptotic and autophagic pathways during thiopurine-induced toxicity in cancer cells: the role of reactive oxygen species

    PubMed Central

    Chaabane, Wiem; Appell, Malin Lindqvist

    2016-01-01

    Thiopurines (azathioprine, 6-mercaptopurine and 6-thioguanine) are a class of genotoxic drugs extensively used in the treatment of various illnesses including leukemia. Their underlying molecular mechanism of action involves the activation of apoptosis and autophagy but remains widely unclear. Here we present evidence that autophagy induction by thiopurines is a survival mechanism that antagonizes apoptosis and is involved in degrading damaged mitochondria through mitophagy. On the other hand, apoptosis is the main cell death mechanism by thiopurines as its inhibition prohibited cell death. Thus a tight interplay between apoptosis and autophagy controls cell fate in response to thiopurine treatment. Moreover, thiopurines disrupt mitochondrial function and induce a loss of the mitochondrial transmembrane potential. The involvement of the mitochondrial pathway in thiopurine-induced apoptosis was further confirmed by increased formation of reactive oxygen species (ROS). Inhibiting oxidative stress protected the cells from thiopurine-induced cell death and ROS scavenging prohibited autophagy induction by thiopurines. Our data indicate that the anticarcinogenic effects of thiopurines are mediated by complex interplay between cellular mechanisms governing redox homeostasis, apoptosis and autophagy. PMID:27689330

  14. The Interrelationship between Abscisic Acid and Reactive Oxygen Species Plays a Key Role in Barley Seed Dormancy and Germination.

    PubMed

    Ishibashi, Yushi; Aoki, Nozomi; Kasa, Shinsuke; Sakamoto, Masatsugu; Kai, Kyohei; Tomokiyo, Reisa; Watabe, Gaku; Yuasa, Takashi; Iwaya-Inoue, Mari

    2017-01-01

    Seed dormancy is one of the adaptive responses in the plant life cycle and an important agronomic trait. Reactive oxygen species (ROS) release seed dormancy and promote seed germination in several cereal crops; however, the key regulatory mechanism of ROS-mediated seed dormancy and germination remains controversial. Here, we focused on the relationship between hydrogen peroxide (a ROS) and abscisic acid (ABA) in dormant and non-dormant barley seeds. The hydrogen peroxide (H2O2) level produced in barley seed embryos after imbibition was higher in non-dormant seeds than in dormant seeds. H2O2 regulated the ABA content in the embryos through ABA-8'-hydroxylase, an ABA catabolic enzyme. Moreover, compared with non-dormant seeds, in dormant seeds the activity of NADPH oxidase, which produces ROS, was lower, whereas the activity of catalase, which is a H2O2 scavenging enzyme, was higher, as was the expression of HvCAT2. Furthermore, precocious germination of isolated immature embryos was suppressed by the transient introduction of HvCAT2 driven by the maize (Zea mays) ubiquitin promoter. HvCAT2 expression was regulated through an ABA-responsive transcription factor (HvABI5) induced by ABA. These results suggest that the changing of balance between ABA and ROS is active in barley seed embryos after imbibition and regulates barley seed dormancy and germination.

  15. Protective effects of kaempferol against reactive oxygen species-induced hemolysis and its antiproliferative activity on human cancer cells.

    PubMed

    Liao, Wenzhen; Chen, Luying; Ma, Xiang; Jiao, Rui; Li, Xiaofeng; Wang, Yong

    2016-05-23

    The protective effects of kaempferol against reactive oxygen species (ROS)-induced hemolysis and its antiproliferative activity on human cancer cells were evaluated in this study. Kaempferol exhibited strong cellular antioxidant ability (CAA) with a CAA value of 59.80 ± 0.379 μM of quercetin (QE)/100 μM (EC50 = 7.74 ± 0.049 μM). Pretreatment with kaempferol significantly attenuated the ROS-induced hemolysis of human erythrocyte (87.4% hemolysis suppressed at 100 μg/mL) and reduced the accumulation of toxic lipid peroxidation product malondialdehyde (MDA). The anti-hemolytic activity of kaempferol was mainly through scavenging excessive ROS and preserving the intrinsic antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; and glutathione peroxidase, GPx) activities in normal levels. Additionally, kaempferol showed significant antiproliferative activity on a panel of human cancer cell lines including human breast carcinoma (MCF-7) cells, human stomach carcinoma (SGC-7901) cells, human cervical carcinoma (Hela) cells and human lung carcinoma (A549) cells. Kaemperol induced apoptosis of MCF-7 cells accompanied with nuclear condensation and mitochondria dysfunction.

  16. The berry constituents quercetin, kaempferol, and pterostilbene synergistically attenuate reactive oxygen species: involvement of the Nrf2-ARE signaling pathway.

    PubMed

    Saw, Constance Lay Lay; Guo, Yue; Yang, Anne Yuqing; Paredes-Gonzalez, Ximena; Ramirez, Christina; Pung, Douglas; Kong, Ah-Ng Tony

    2014-10-01

    Quercetin, kaempferol, and pterostilbene are abundant in berries. The anti-oxidative properties of these constituents may contribute to cancer chemoprevention. However, their precise mechanisms of action and their combinatorial effects are not completely understood. Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) regulates anti-oxidative stress enzymes and Phase II drug metabolizing/detoxifying enzymes by binding to antioxidant response element (ARE). This study aimed to investigate the anti-oxidative stress activities of quercetin, kaempferol, and pterostilbene individually and in combination, as well as the involvement of the Nrf2-ARE signaling pathway. Quercetin, kaempferol, and pterostilbene all exhibited strong free-radical scavenging activity in the DPPH assay. The MTS assay revealed that low concentration combinations we tested were relatively non-toxic to HepG2-C8 cells. The results of the DCFH-DA assay and combination index (CI) indicated that quercetin, kaempferol, and pterostilbene attenuated intracellular reactive oxygen species (ROS) levels when pretreated individually and had synergistic effects when used in combination. In addition, the combination treatment significantly induced ARE and increased the mRNA and protein expression of Nrf2-regulated genes. Collectively, our study demonstrated that the berry constituents quercetin, kaempferol, and pterostilbene activated the Nrf2-ARE signaling pathway and exhibited synergistic anti-oxidative stress activity at appropriate concentrations.

  17. From intracellular signaling networks to cell death: the dual role of reactive oxygen species in seed physiology.

    PubMed

    Bailly, Christophe; El-Maarouf-Bouteau, Hayat; Corbineau, Françoise

    2008-10-01

    Reactive Oxygen Species (ROS) are continuously produced during seed development, from embryogenesis to germination, but also during seed storage. ROS play a dual role in seed physiology behaving, on the one hand, as actors of cellular signaling pathways and, on the other hand, as toxic products that accumulate under stress conditions. ROS, provided that their amount is tightly regulated by the balance between production and scavenging, appear now as being beneficial for germination, and in particular to act as a positive signal for seed dormancy release. Such an effect might result from the interplay between ROS and hormone signaling pathways thus leading to changes in gene expression or in cellular redox status. We also propose that changes in ROS homeostasis would play a role in perception of environmental factors by seeds during their germination, and thus act as a signal controlling the completion of germination. However, uncontrolled accumulation of ROS is likely to occur during seed aging or seed desiccation thus leading to oxidative damage toward a wide range of biomolecules and ultimately to necroses and cell death. We present here the concept of the "oxidative window for germination", which restricts the occurrence of the cellular events associated with germination to a critical range of ROS level, enclosed by lower and higher limits. Above or below the "oxidative window for germination", weak or high amounts of ROS, respectively, would not permit progress toward germination.

  18. Laser irradiation of mouse spermatozoa enhances in-vitro fertilization and Ca2+ uptake via reactive oxygen species

    NASA Astrophysics Data System (ADS)

    Cohen, Natalie; Lubart, Rachel; Rubinstein, Sara; Breitbart, Haim

    1996-11-01

    630 nm He-Ne laser irradiation was found to have a profound influence on Ca2+ uptake in mouse spermatozoa and the fertilizing potential of these cells. Laser irradiation affected mainly the mitochondrial Ca2+ transport mechanisms. Furthermore, the effect of light was found to be Ca2+-dependent. We demonstrate that reactive oxygen species (ROS) are involved in the cascade of biochemical events evoked by laser irradiation. A causal association between laser irradiation, ROS generation, and sperm function was indicated by studies with ROS scavengers, superoxide dismutase (SOD) and catalase, and exogenous hydrogen peroxide. SOD treatment resulted in increased Ca2+ uptake and in enhanced fertilization rate. Catalase treatment impaired the light-induced stimulation in Ca2+ uptake and fertilization rate. Exogenous hydrogen peroxide was found to enhance Ca2+ uptake in mouse spermatozoa and the fertilizing capability of these cells in a dose-dependent manner. These results suggest that the effect of 630 nm He-Ne laser irradiation is mediated through the generation of hydrogen peroxide by the spermatozoa and that this effect plays a significant role in the augmentation of the sperm cells' capability to fertilize metaphase II-arrested eggs in-vitro.

  19. Roles of Reactive Oxygen and Nitrogen Species in Pain

    PubMed Central

    Salvemini, Daniela; Little, Joshua W.; Doyle, Timothy; Neumann, William L.

    2011-01-01

    Peroxynitrite (PN, ONOO−) and its reactive oxygen precursor superoxide (SO, O2·−), are critically important in the development of pain of several etiologies including in the development of pain associated with chronic use of opiates such as morphine (also known as opiate-induced hyperalgesia and antinociceptive tolerance). This is now an emerging field in which considerable progress has been made in terms of understanding the relative contribution of SO, PN, and nitroxidative stress in pain signaling at the molecular and biochemical levels. Aggressive research in this area is poised to provide the pharmacological basis for development of novel non-narcotic analgesics that are based upon the unique ability to selectively eliminate SO and/or PN. As we have a better understanding of the role of SO and PN in pathophysiological settings, targeting PN may be a better therapeutic strategy than targeting SO. This is due to the fact that unlike PN, which has no currently known beneficial role, SO may play a significant role in learning and memory [1]. Thus, the best approach may be to spare SO while directly targeting its downstream product, PN. Over the last 15 years, our team has spearheaded research concerning the roles of SO/PN in pain and these results are currently leading to the development of solid therapeutic strategies in this important area. PMID:21277369

  20. Roles of reactive oxygen and nitrogen species in pain.

    PubMed

    Salvemini, Daniela; Little, Joshua W; Doyle, Timothy; Neumann, William L

    2011-09-01

    Peroxynitrite (PN; ONOO⁻) and its reactive oxygen precursor superoxide (SO; O₂•⁻) are critically important in the development of pain of several etiologies including pain associated with chronic use of opiates such as morphine (also known as opiate-induced hyperalgesia and antinociceptive tolerance). This is now an emerging field in which considerable progress has been made in terms of understanding the relative contributions of SO, PN, and nitroxidative stress in pain signaling at the molecular and biochemical levels. Aggressive research in this area is poised to provide the pharmacological basis for development of novel nonnarcotic analgesics that are based upon the unique ability to selectively eliminate SO and/or PN. As we have a better understanding of the roles of SO and PN in pathophysiological settings, targeting PN may be a better therapeutic strategy than targeting SO. This is because, unlike PN, which has no currently known beneficial role, SO may play a significant role in learning and memory. Thus, the best approach may be to spare SO while directly targeting its downstream product, PN. Over the past 15 years, our team has spearheaded research concerning the roles of SO and PN in pain and these results are currently leading to the development of solid therapeutic strategies in this important area.

  1. Reactive Oxygen Species on the Early Earth and Survival of Bacteria

    NASA Technical Reports Server (NTRS)

    Balk, Melikea; Mason, Paul; Stams, Alfons J. M.; Smidt, Hauke; Freund, Friedemann; Rothschild, Lynn

    2011-01-01

    An oxygen-rich atmosphere appears to have been a prerequisite for complex, multicellular life to evolve on Earth and possibly elsewhere in the Universe. However it remains unclear how free oxygen first became available on the early Earth. A potentially important, and as yet poorly constrained pathway, is the production of oxygen through the weathering of rocks and release into the near-surface environment. Reactive Oxygen Species (ROS), as precursors to molecular oxygen, are a key step in this process, and may have had a decisive impact on the evolution of life, present and past. ROS are generated from minerals in igneous rocks during hydrolysis of peroxy defects, which consist of pairs of oxygen anions oxidized to the valence state -1 and during (bio) transformations of iron sulphide minerals. ROS are produced and consumed by intracellular and extracellular reactions of Fe, Mn, C, N, and S species. We propose that, despite an overall reducing or neutral oxidation state of the macroenvironment and the absence of free O2 in the atmosphere, organisms on the early Earth had to cope with ROS in their microenvironments. They were thus under evolutionary pressure to develop enzymatic and other defences against the potentially dangerous, even lethal effects of oxygen and its derived ROS. Conversely it appears that microorganisms learned to take advantage of the enormous reactive potential and energy gain provided by nascent oxygen. We investigate how oxygen might be released through weathering. We test microorganisms in contact with rock surfaces and iron sulphides. We model bacteria such as Deionococcus radiodurans and Desulfotomaculum, Moorella and Bacillus species for their ability to grow or survive in the presence of ROS. We examine how early Life might have adapted to oxygen.

  2. Asymmetric dimethylarginine and reactive oxygen species: unwelcome twin visitors to the cardiovascular and kidney disease tables.

    PubMed

    Wilcox, Christopher S

    2012-02-01

    Plasma levels of asymmetric dimethylarginine or markers of reactive oxygen species are increased in subjects with risk factors for cardiovascular disease or chronic kidney disease. We tested the hypothesis that reactive oxygen species generate cellular asymmetric dimethylarginine that together cause endothelial dysfunction that underlies the risk of subsequent disease. Rat preglomerular vascular smooth muscle cells transfected with p22(phox) had increased NADPH oxidase activity, enhanced activity and expression of protein arginine methyltransferase, and reduced activity and protein expression of dimethylarginine dimethylaminotransferase and of cationic amino acid transferase 1 resulting in increased cellular levels of asymmetric dimethylarginine. Rats infused with angiotensin II had oxidative stress. The endothelial function of their mesenteric arterioles was changed from vasodilatation to vasoconstriction, accompanied by increased vascular asymmetric dimethylarginine. All of these changes were prevented by Tempol. In vivo silencing of dimethylarginine dimethylaminotransferase 1 increased plasma levels of asymmetric dimethylarginine, whereas silencing of dimethylarginine dimethylaminotransferase 2 impaired endothelial function. We suggest that initiation factors, such as angiotensin II, expressed in blood vessels or tissues of subjects with cardiovascular and kidney disease risk factors generate reactive oxygen species from NADPH oxidase that enhances cellular asymmetric dimethylarginine in an amplification loop. This leads to adverse changes in vascular and organ functions, as a consequence of reduced tissue levels of NO and increased reactive oxygen species. Thus, we conclude that reactive oxygen species and asymmetric dimethylarginine form a tightly coupled amplification system that translates cardiovascular/kidney risk into overt disease.

  3. The Scientist Scavenger Hunt.

    ERIC Educational Resources Information Center

    Morphew, Valerie N.; Key, Kathleen

    1994-01-01

    Using a well-planned scavenger hunt, students' awareness of the significance of minorities and women in science is enhanced. Provides a sample scavenger hunt and resource list as well as activities for extension. (ZWH)

  4. Heat-induced formation of reactive oxygen species and 8-oxoguanine, a biomarker of damage to DNA

    PubMed Central

    Bruskov, Vadim I.; Malakhova, Lyudmila V.; Masalimov, Zhaksylyk K.; Chernikov, Anatoly V.

    2002-01-01

    Heat-induced formation of 8-oxoguanine was demonstrated in DNA solutions in 10–3 M phosphate buffer, pH 6.8, by enzyme-linked immunosorbent assays using monoclonal antibodies against 8-oxoguanine. A radiation-chemical yield of 3.7 × 10–2 µmol J–1 for 8-oxoguanine production in DNA upon γ-irradiation was used as an adequate standard for quantitation of 8-oxoguanine in whole DNA. The initial yield of heat-induced 8-oxoguanine exhibits first order kinetics. The rate constants for 8-oxoguanine formation were determined at elevated temperatures; the activation energy was found to be 27 ± 2 kcal/mol. Extrapolation to 37°C gave a value of k37 = 4.7 × 10–10 s–1. Heat-induced 8-oxoguanine formation and depurination of guanine and adenine show similarities of the processes, which implies that heat-mediated generation of reactive oxygen species (ROS) should occur. Heat-induced production of H2O2 in phosphate buffer was shown. The sequence of reactions of thermally mediated ROS formation have been established: activation of dissolved oxygen to the singlet state, generation of superoxide radicals and their dismutation to H2O2. Gas saturation (O2, N2 and Ar), D2O, scavengers of 1O2, O2–• and OH• radicals and metal chelators influenced heat-induced 8-oxoguanine formation as they affected thermal ROS generation. These findings imply that heat acts via ROS attack leading to oxidative damage to DNA. PMID:11884633

  5. Scavenging for the Past.

    ERIC Educational Resources Information Center

    McMahon, Sue; Strubbe, Mary

    1988-01-01

    Discusses the goals and planning of a scavenger hunt which was designed to increase enthusiasm in students and promote active learning. States that a scavenger hunt instills a sense of community pride in students and that the community cooperation fosters a positive relationship with the school. Provides a sample scavenger hunt checklist. (GEA)

  6. Effects of coordination number of Au catalyst on oxygen species and their catalytic roles

    NASA Astrophysics Data System (ADS)

    Ouyang, Gen; Zhu, Kong-Jie; Zhang, Lei; Cui, Peng-Fei; Teng, Bo-Tao; Wen, Xiao-Dong

    2016-11-01

    To explore the effects of coordination number of Au nanoparticles on oxygen species and their catalytic roles is very important in gold catalysis. Based on the systematic study of oxygen adsorption on Au(997) by density functional theory calculation, the quantitative correlation for different oxygen species with coverage and Au coordination number is established in theory. The only O adatoms near step area with relatively low Au coordination numbers exist at low coverage (<1/18 ML), O adatoms adsorb at terrace areas with relatively high Au coordination numbers at medium coverage (1/18-2/9 ML); while oxygen islands form at high coverage (>2/9 ML). The theoretical predictions are in good agreement with the experimental observations in TDS spectrum. On the basis of Langmuir-Hinschelwood and Eley-Rideal mechanisms for NO oxidation, the activities of the three different oxygen species also exhibit correlation with Au coordination number. The oxygen island shows the highest oxidation activity, followed by the O adatom at terrace surface; while the O adatom near step area has the lowest oxidative performance. This work will shed light into the understanding of gold catalysis.

  7. Super-oxidation of silicon nanoclusters: magnetism and reactive oxygen species at the surface

    SciTech Connect

    Lepeshkin, Sergey; Baturin, Vladimir; Tikhonov, Evgeny; Matsko, Nikita; Uspenskii, Yurii; Naumova, Anastasia; Feya, Oleg; Schoonen, Martin A.; Oganov, Artem R.

    2016-01-01

    Oxidation of silicon nanoclusters depending on the temperature and oxygen pressure is explored from first principles using the evolutionary algorithm, and structural and thermodynamic analysis. From our calculations of 90 SinOm clusters we found that under normal conditions oxidation does not stop at the stoichiometric SiO2 composition, as it does in bulk silicon, but goes further placing extra oxygen atoms on the cluster surface. These extra atoms are responsible for light emission, relevant to reactive oxygen species and many of them are magnetic. We argue that the super-oxidation effect is size-independent and discuss its relevance to nanotechnology and miscellaneous applications, including biomedical ones.

  8. Measuring reactive oxygen and nitrogen species with fluorescent probes: challenges and limitations

    PubMed Central

    Kalyanaraman, Balaraman; Darley-Usmar, Victor; Davies, Kelvin J.A.; Dennery, Phyllis A.; Forman, Henry Jay; Grisham, Matthew B.; Mann, Giovanni E.; Moore, Kevin; Roberts, L. Jackson; Ischiropoulos, Harry

    2013-01-01

    The purpose of this position paper is to present a critical analysis of the challenges and limitations of the most widely used fluorescent probes for detecting and measuring reactive oxygen and nitrogen species. Where feasible, we have made recommendations for the use of alternate probes and appropriate analytical techniques that measure the specific products formed from the reactions between fluorescent probes and reactive oxygen and nitrogen species. We have proposed guidelines that will help present and future researchers with regard to the optimal use of selected fluorescent probes and interpretation of results. PMID:22027063

  9. Electron Spin Resonance (ESR) detection of active oxygen species and organic phases in Martian soils

    NASA Technical Reports Server (NTRS)

    Tsay, Fun-Dow; Kim, Soon Sam; Liang, Ranty H.

    1989-01-01

    The presence of active oxygen species (O(-), O2(-), O3(-)) and other strong oxidants (Fe2O3 and Fe3O4) was invoked in interpretations of the Viking biological experiments and a model was also suggested for Martian surface chemistry. The non-biological interpretations of the biological results gain futher support as no organic compounds were detected in the Viking pyrolysis-gas chromatography mass spectrometer (GCSM) experiments at concentrations as low as 10 ppb. Electron spin resonance (ESR) measures the absorption of microwaves by a paramagnetic and/or ferromagnetic center in the presence of an external field. In many instances, ESR has the advantage of detailed submicroscopic identification of the transient species and/or unstable reaction intermediates in their environments. Since the higly active oxygen species (O(-), O2(-), O3(-), and R-O-O(-)) are all paramagnetic in nature, they can be readily detected in native form by the ESR method. Active oxygen species likely to occur in the Martian surface samples were detected by ESR in UV-irradiated samples containing MgO. A miniaturized ESR spectrometer system can be developed for the Mars Rover Sample Return Mission. The instrument can perform the following in situ Martian samples analyses: detection of active oxygen species; characterization of Martian surface chemistry and photooxidation processes; and searching for organic compounds in the form of free radicals preserved in subsoils, and detection of microfossils with Martian carbonate sediments.

  10. Chlamydia muridarum infection of macrophages elicits bactericidal nitric oxide production via reactive oxygen species and cathepsin B.

    PubMed

    Rajaram, Krithika; Nelson, David E

    2015-08-01

    The ability of certain species of Chlamydia to inhibit the biogenesis of phagolysosomes permits their survival and replication within macrophages. The survival of macrophage-adapted chlamydiae correlates with the multiplicity of infection (MOI), and optimal chlamydial growth occurs in macrophages infected at an MOI of ≤1. In this study, we examined the replicative capacity of Chlamydia muridarum in the RAW 264.7 murine macrophage cell line at different MOIs. C. muridarum productively infected these macrophages at low MOIs but yielded few viable elementary bodies (EBs) when macrophages were infected at a moderate (10) or high (100) MOI. While high MOIs caused cytotoxicity and irreversible host cell death, macrophages infected at a moderate MOI did not show signs of cytotoxicity until late in the infectious cycle. Inhibition of host protein synthesis rescued C. muridarum in macrophages infected at a moderate MOI, implying that chlamydial growth was blocked by activated defense mechanisms. Conditioned medium from these macrophages was antichlamydial and contained elevated levels of interleukin 1β (IL-1β), IL-6, IL-10, and beta interferon (IFN-β). Macrophage activation depended on Toll-like receptor 2 (TLR2) signaling, and cytokine production required live, transcriptionally active chlamydiae. A hydroxyl radical scavenger and inhibitors of inducible nitric oxide synthase (iNOS) and cathepsin B also reversed chlamydial killing. High levels of reactive oxygen species (ROS) led to an increase in cathepsin B activity, and pharmacological inhibition of ROS and cathepsin B reduced iNOS expression. Our data demonstrate that MOI-dependent TLR2 activation of macrophages results in iNOS induction via a novel ROS- and cathepsin-dependent mechanism to facilitate C. muridarum clearance.

  11. Dominant Presence of Oxygenated Organic Species in the Remote Southern Hemisphere Troposphere

    NASA Technical Reports Server (NTRS)

    Singh, H.; Chen, Y.; Staudt, A.; Jacob, D.; Blake, D.; Heikes, B.; Snow, J.; Hipskind, R. Stephen (Technical Monitor)

    2000-01-01

    Oxygenated organic species are intimately involved with the fate of nitrogen oxides (NO(sub x)) and hydrogen oxides (HO(sub x)), which are necessary for tropospheric ozone formation. A recent airborne experiment (March-April, 1999) focused over the southern hemisphere (SH) Pacific Ocean (PEM-tropics-B) provided a first opportunity for a detailed characterization of the oxygenated organic composition of the remote southern hemisphere troposphere. Three co-located multi-channel airborne instruments measured a dozen key oxygenated species (carbonyls, alcohols, organic nitrates, organic pernitrates, peroxides) along with a comprehensive suite of C2-C8 Nonmethane hydrocarbons (NMHC). These measurements reveal that in the tropical SH (0-30 deg south), oxygenated chemical abundances are extremely large and collectively are nearly five times those of NMHC. Even in the NH remote atmospheres their burden is equal to or greater than that of NMHC. The relatively uniform global distribution oxygenates (EPSILON Ox-org) is indicative of the presence of large natural and distributed sources. A global 3-D model, reflecting the present state of science, is unable to correctly simulate the atmospheric distribution and variability of several of these species.

  12. Responses of Solid Tumor Cells in DMEM to Reactive Oxygen Species Generated by Non-Thermal Plasma and Chemically Induced ROS Systems

    NASA Astrophysics Data System (ADS)

    Kaushik, Neha; Uddin, Nizam; Sim, Geon Bo; Hong, Young June; Baik, Ku Youn; Kim, Chung Hyeok; Lee, Su Jae; Kaushik, Nagendra Kumar; Choi, Eun Ha

    2015-02-01

    In this study, we assessed the role of different reactive oxygen species (ROS) generated by soft jet plasma and chemical-induced ROS systems with regard to cell death in T98G, A549, HEK293 and MRC5 cell lines. For a comparison with plasma, we generated superoxide anion (O2-), hydroxyl radical (HO.), and hydrogen peroxide (H2O2) with chemicals inside an in vitro cell culture. Our data revealed that plasma decreased the viability and intracellular ATP values of cells and increased the apoptotic population via a caspase activation mechanism. Plasma altered the mitochondrial membrane potential and eventually up-regulated the mRNA expression levels of BAX, BAK1 and H2AX gene but simultaneously down-regulated the levels of Bcl-2 in solid tumor cells. Moreover, a western blot analysis confirmed that plasma also altered phosphorylated ERK1/2/MAPK protein levels. At the same time, using ROS scavengers with plasma, we observed that scavengers of HO. (mannitol) and H2O2 (catalase and sodium pyruvate) attenuated the activity of plasma on cells to a large extent. In contrast, radicals generated by specific chemical systems enhanced cell death drastically in cancer as well as normal cell lines in a dose-dependent fashion but not specific with regard to the cell type as compared to plasma.

  13. Nitric oxide production occurs downstream of reactive oxygen species in guard cells during stomatal closure induced by chitosan in abaxial epidermis of Pisum sativum.

    PubMed

    Srivastava, Nupur; Gonugunta, Vijay K; Puli, Mallikarjuna R; Raghavendra, Agepati S

    2009-03-01

    The effects of chitosan (beta-1,4 linked glucosamine, a fungal elicitor), on the patterns of stomatal movement and signaling components were studied. cPTIO (NO scavenger), sodium tungstate (nitrate reductase inhibitor) or L: -NAME (NO synthase inhibitor) restricted the chitosan induced stomatal closure, demonstrating that NO is an essential factor. Similarly, catalase (H(2)O(2) scavenger) or DPI [NAD(P)H oxidase inhibitor] and BAPTA-AM or BAPTA (calcium chelators) prevented chitosan induced stomatal closure, suggesting that reactive oxygen species (ROS) and calcium were involved during such response. Monitoring the NO and ROS production in guard cells by fluorescent probes (DAF-2DA and H(2)DCFDA) indicated that on exposure to chitosan, the levels of NO rose after only 10 min, while those of ROS increased already by 5 min. cPTIO or sodium tungstate or L: -NAME prevented the rise in NO levels but did not restrict the ROS production. In contrast, catalase or DPI restricted the chitosan-induced production of both ROS and NO in guard cells. The calcium chelators, BAPTA-AM or BAPTA, did not have a significant effect on the chitosan induced rise in NO or ROS. We propose that the production of NO is an important signaling component and participates downstream of ROS production. The effects of chitosan strike a marked similarity with those of ABA or MJ on guard cells and indicate the convergence of their signal transduction pathways leading to stomatal closure.

  14. A time course assessment of changes in reactive oxygen species generation and antioxidant defense in hydroponically grown wheat in response to lead ions (Pb2+).

    PubMed

    Kaur, Gurpreet; Singh, Harminder Pal; Batish, Daizy Rani; Kohli, Ravinder Kumar

    2012-10-01

    We examined the effect of Pb(2+) (8 and 40 mg l(-1)) on reactive oxygen species generation and alterations in antioxidant enzymes in hydroponically grown wheat at 24, 72, and 120 h after exposure. Pb(2+) toxicity was more pronounced on root growth, and it correlated with the greater Pb accumulation in roots. Pb exposure (40 mg l(-1)) enhanced superoxide anion, H(2)O(2), and MDA content in wheat roots by 1.9- to 2.2-folds, 56-255%, and 41-90%, respectively, over the control. Pb-induced loss of membrane integrity was confirmed by the enhanced electrolyte leakage and in vivo histochemical localization. Activities of scavenging enzymes, superoxide dismutases and catalases, enhanced in Pb-treated wheat roots by 1.4- to 5.7-folds over that in the control. In contrast, the activities of ascorbate and guaiacol peroxidases and glutathione reductases decreased significantly, suggesting their non-involvement in detoxification process. The study concludes that Pb(2+)-induced oxidative damage in wheat roots involve greater H(2)O(2) accumulation and the deactivation of the related scavenging enzymes.

  15. Deoxyamphimedine, a Pyridoacridine Alkaloid, Damages DNA via the Production of Reactive Oxygen Species

    PubMed Central

    Marshall, Kathryn M.; Andjelic, Cynthia D.; Tasdemir, Deniz; Concepción, Gisela P.; Ireland, Chris M.; Barrows, Louis R.

    2009-01-01

    Marine pyridoacridines are a class of aromatic chemicals that share an 11H-pyrido[4,3,2-mn]acridine skeleton. Pyridoacridine alkaloids display diverse biological activities including cytotoxicity, fungicidal and bactericidal properties, production of reactive oxygen species (ROS) and topoisomerase inhibition. These activities are often dependent on slight modifications to the pyridoacridine skeleton. Here we demonstrate that while structurally similar to neoamphimedine and amphimedine, the biological activity of deoxyamphimedine differs greatly. Deoxyamphimedine damages DNA in vitro independent of topoisomerase enzymes through the generation of reactive oxygen species. Its activity was decreased in low oxygen, with the removal of a reducing agent and in the presence of anti-oxidants. Deoxyamphimedine also showed enhanced toxicity in cells sensitive to single or double strand DNA breaks, consistent with the in vitro activity. PMID:19597581

  16. Deoxyamphimedine, a pyridoacridine alkaloid, damages DNA via the production of reactive oxygen species.

    PubMed

    Marshall, Kathryn M; Andjelic, Cynthia D; Tasdemir, Deniz; Concepción, Gisela P; Ireland, Chris M; Barrows, Louis R

    2009-05-25

    Marine pyridoacridines are a class of aromatic chemicals that share an 11H-pyrido[4,3,2-mn]acridine skeleton. Pyridoacridine alkaloids display diverse biological activities including cytotoxicity, fungicidal and bactericidal properties, production of reactive oxygen species (ROS) and topoisomerase inhibition. These activities are often dependent on slight modifications to the pyridoacridine skeleton. Here we demonstrate that while structurally similar to neoamphimedine and amphimedine, the biological activity of deoxyamphimedine differs greatly. Deoxyamphimedine damages DNA in vitro independent of topoisomerase enzymes through the generation of reactive oxygen species. Its activity was decreased in low oxygen, with the removal of a reducing agent and in the presence of anti-oxidants. Deoxyamphimedine also showed enhanced toxicity in cells sensitive to single or double strand DNA breaks, consistent with the in vitro activity.

  17. Release of elicitors from rice blast spores under the action of reactive oxygen species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effects of reactive oxygen species (ROS) on secretion of hypothesized elicitors from spores of rice blast causal fungus Magnaporthe grisea were studied. For spore exposure to exogenous ROS, they were germinated for 5 h in 50 µM H2O2 followed by addition of catalase E.C. 1.11.1.6 (to decompose pe...

  18. [Reactive oxygen species and 3,4-dihydroxyphenylacetaldehyde in pathogenesis of Parkinson disease].

    PubMed

    Rybakowska, Iwona; Szreder, Grzegorz; Kaletha, Krystian; Barwina, Małgorzata; Waldman, Wojciech; Sein Anand, Jacek

    2011-01-01

    Reactive oxygen species, which plays a role in pathogenesis of many neurodegenerative diseases, seems to be important also in pathogenesis of the Parkinson's disease. Experiments performed recently, revealed in the cerebrum of patients suffering from this disease (induced by the oxidative stress) elevated levels of 3,4-dihydroxyphenylacetaldehyde (DOPAL)--a strong endogenous neurotoxin to dopamine neurons.

  19. Reactive oxygen species in photochemistry of the red fluorescent protein "Killer Red".

    PubMed

    Vegh, Russell B; Solntsev, Kyril M; Kuimova, Marina K; Cho, Soohee; Liang, Yue; Loo, Bernard L W; Tolbert, Laren M; Bommarius, Andreas S

    2011-05-07

    The fluorescent protein aptly named "Killer Red" (KRed) is capable of killing transfected cells and inactivating fused proteins upon exposure to visible light in the presence of oxygen. We have investigated the source of the bioactive species through a variety of photophysical and photochemical techniques. Our results indicate a Type I (electron transfer mediated) photosensitizing mechanism.

  20. Mitochondrial function and reactive oxygen species action in relation to boar motility.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Flow cytometric assays of viable boar sperm were developed to measure reactive oxygen species (ROS) formation (oxidization of hydroethidine to ethidium), membrane lipid peroxidation (oxidation of lipophilic probe C11-BODIPY581/591), and mitochondrial inner transmembrane potential (aggregation of mit...

  1. Effects of reactive oxygen species action on sperm function in spermatozoa

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reactive oxygen species (ROS) formation and lipid peroxidation have been recognized as problems for sperm survival and fertility. The precise roles and detection of superoxide (SO), hydrogen peroxide (HP), and membrane lipid peroxidation have been problematic because of the low specificity and sens...

  2. Production of Reactive Oxygen Species by Photosystem II as a Response to Light and Temperature Stress

    PubMed Central

    Pospíšil, Pavel

    2016-01-01

    The effect of various abiotic stresses on photosynthetic apparatus is inevitably associated with formation of harmful reactive oxygen species (ROS). In this review, recent progress on ROS production by photosystem II (PSII) as a response to high light and high temperature is overviewed. Under high light, ROS production is unavoidably associated with energy transfer and electron transport in PSII. Singlet oxygen is produced by the energy transfer form triplet chlorophyll to molecular oxygen formed by the intersystem crossing from singlet chlorophyll in the PSII antennae complex or the recombination of the charge separated radical pair in the PSII reaction center. Apart to triplet chlorophyll, triplet carbonyl formed by lipid peroxidation transfers energy to molecular oxygen forming singlet oxygen. On the PSII electron acceptor side, electron leakage to molecular oxygen forms superoxide anion radical which dismutes to hydrogen peroxide which is reduced by the non-heme iron to hydroxyl radical. On the PSII electron donor side, incomplete water oxidation forms hydrogen peroxide which is reduced by manganese to hydroxyl radical. Under high temperature, dark production of singlet oxygen results from lipid peroxidation initiated by lipoxygenase, whereas incomplete water oxidation forms hydrogen peroxide which is reduced by manganese to hydroxyl radical. The understanding of molecular basis for ROS production by PSII provides new insight into how plants survive under adverse environmental conditions. PMID:28082998

  3. Scavenging of H2O2 by mouse brain mitochondria

    PubMed Central

    Starkov, Anatoly A.; Andreyev, Alexander Yu; Zhang, Steven F.; Starkova, Natalia N.; Korneeva, Maria; Syromyatnikov, Mikhail; Popov, Vasily N.

    2015-01-01

    Mitochondrial reactive oxygen species (ROS) metabolism is unique in that mitochondria both generate and scavenge ROS. Recent estimates of ROS scavenging capacity of brain mitochondria are surprisingly high, ca. 9-12 nmol H2O2/min/mg, which is ~100 times higher than the rate of ROS generation. This raises a question whether brain mitochondria are a source or a sink of ROS. We studied the interaction between ROS generation and scavenging in mouse brain mitochondria by measuring the rate of removal of H2O2 added at a concentration of 0.4 μM, which is close to the reported physiological H2O2 concentrations in tissues, under conditions of low and high levels of mitochondrial H2O2 generation. With NAD-linked substrates, the rate of H2O2 generation by mitochondria was ~50–70 pmol/min/mg. The H2O2 scavenging dynamics was best approximated by the first order reaction equation. H2O2 scavenging was not affected by the uncoupling of mitochondria, phosphorylation of added ADP, or the genetic ablation of glutathione peroxidase 1, but decreased in the absence of respiratory substrates, in the presence of thioredoxin reductase inhibitor auranofin, or in partially disrupted mitochondria. With succinate, the rate of H2O2 generation was ~2,200–2,900 pmol/min/mg; the scavenging of added H2O2 was masked by a significant accumulation of generated H2O2 in the assay medium. The obtained data were fitted into a simple model that reasonably well described the interaction between H2O2 scavenging and production. It showed that mitochondria are neither a sink nor a source of H2O2, but can function as both at the same time, efficiently stabilizing exogenous H2O2 concentration at a level directly proportional to the ratio of the H2O2 generation rate to the rate constant of the first order scavenging reaction. PMID:25248416

  4. Elevated Cytosolic Na+ Increases Mitochondrial Formation of Reactive Oxygen Species in Failing Cardiac Myocytes

    PubMed Central

    Kohlhaas, Michael; Liu, Ting; Knopp, Andreas; Zeller, Tanja; Ong, Mei Fang; Böhm, Michael; O'Rourke, Brian; Maack, Christoph

    2010-01-01

    Background —Oxidative stress is causally linked to the progression of heart failure, and mitochondria are critical sources of reactive oxygen species in failing myocardium. We previously observed that in heart failure, elevated cytosolic Na+ ([Na+]i) reduces mitochondrial Ca2+ ([Ca2+]m) by accelerating Ca2+ efflux via the mitochondrial Na+/Ca2+ exchanger. Because the regeneration of antioxidative enzymes requires NADPH, which is indirectly regenerated by the Krebs cycle, and Krebs cycle dehydrogenases are activated by [Ca2+]m, we speculated that in failing myocytes, elevated [Na+]i promotes oxidative stress. Methods and Results —We used a patch-clamp–based approach to simultaneously monitor cytosolic and mitochondrial Ca2+ and, alternatively, mitochondrial H2O2 together with NAD(P)H in guinea pig cardiac myocytes. Cells were depolarized in a voltage-clamp mode (3 Hz), and a transition of workload was induced by β-adrenergic stimulation. During this transition, NAD(P)H initially oxidized but recovered when [Ca2+]m increased. The transient oxidation of NAD(P)H was closely associated with an increase in mitochondrial H2O2 formation. This reactive oxygen species formation was potentiated when mitochondrial Ca2+ uptake was blocked (by Ru360) or Ca2+ efflux was accelerated (by elevation of [Na+]i). In failing myocytes, H2O2 formation was increased, which was prevented by reducing mitochondrial Ca2+ efflux via the mitochondrial Na+/Ca2+ exchanger. Conclusions —Besides matching energy supply and demand, mitochondrial Ca2+ uptake critically regulates mitochondrial reactive oxygen species production. In heart failure, elevated [Na+]i promotes reactive oxygen species formation by reducing mitochondrial Ca2+ uptake. This novel mechanism, by which defects in ion homeostasis induce oxidative stress, represents a potential drug target to reduce reactive oxygen species production in the failing heart. PMID:20351235

  5. Scavenging by chimpanzees at Ngogo and the relevance of chimpanzee scavenging to early hominin behavioral ecology.

    PubMed

    Watts, David P

    2008-01-01

    Chimpanzees regularly hunt a variety of prey species. However, they rarely scavenge, which distinguishes chimpanzee carnivory from that of some modern hunter-gatherers and, presumably, at least some Plio-Pleistocene hominins. I use observations made over an 11-year period to document all known opportunities for scavenging encountered by chimpanzees at Ngogo, Kibale National Park, Uganda, and describe all cases of scavenging. I also review data on scavenging from other chimpanzee research sites. Chimpanzees at Ngogo encountered scavenging opportunities only about once per 100 days and ate meat from scavenged carcasses only four times. Scavenging opportunities are also rare at other sites, even where leopards are present (Mahale, Taï, Gombe), and scavenging of leopard kills is known only from Mahale. Feeding on prey that chimpanzees had hunted but then abandoned is the most common form of scavenging reported across study sites. For example, several individuals at Ngogo ate meat from a partially consumed red colobus carcass abandoned after a hunt the previous day. Such behavior probably was not common among Oldowan hominins. Ngogo data and those from other sites also show that chimpanzees sometimes eat meat from carcasses of prey that they did not see killed and that were not killed by chimpanzees, and that scavenging allows access to carcasses larger than those of any prey items. However, chimpanzees ignore relatively many opportunities to obtain meat from such carcasses. Scavenging may be rare because fresh carcasses are rare, because the risk of bacterial infections and zoonoses is high, and because chimpanzees may not recognize certain species as potential prey or certain size classes of prey species as food sources. Its minimal nutritional importance, along with the absence of technology to facilitate confrontational scavenging and rapid carcass processing, apparently distinguishes chimpanzee foraging strategies from those of at least some Oldowan hominins.

  6. NADPH oxidase-derived reactive oxygen species contribute to impaired cutaneous microvascular function in chronic kidney disease.

    PubMed

    DuPont, Jennifer J; Ramick, Meghan G; Farquhar, William B; Townsend, Raymond R; Edwards, David G

    2014-06-15

    Oxidative stress promotes vascular dysfunction in chronic kidney disease (CKD). We utilized the cutaneous circulation to test the hypothesis that reactive oxygen species derived from NADPH oxidase and xanthine oxidase impair nitric oxide (NO)-dependent cutaneous vasodilation in CKD. Twenty subjects, 10 stage 3 and 4 patients with CKD (61 ± 4 yr; 5 men/5 women; eGFR: 39 ± 4 ml·min(-1)·1.73 m(-2)) and 10 healthy controls (55 ± 2 yr; 4 men/6 women; eGFR: >60 ml·min(-1)·1.73 m(-2)) were instrumented with 4 intradermal microdialysis fibers for the delivery of 1) Ringer solution (Control), 2) 10 μM tempol (scavenge superoxide), 3) 100 μM apocynin (NAD(P)H oxidase inhibition), and 4) 10 μM allopurinol (xanthine oxidase inhibition). Skin blood flow was measured via laser-Doppler flowmetry during standardized local heating (42°C). N(g)-nitro-l-arginine methyl ester (L-NAME; 10 mM) was infused to quantify the NO-dependent portion of the response. Cutaneous vascular conductance (CVC) was calculated as a percentage of the maximum CVC achieved during sodium nitroprusside infusion at 43°C. Cutaneous vasodilation was attenuated in patients with CKD (77 ± 3 vs. 88 ± 3%, P = 0.01), but augmented with tempol and apocynin (tempol: 88 ± 2 (P = 0.03), apocynin: 91 ± 2% (P = 0.001). The NO-dependent portion of the response was reduced in patients with CKD (41 ± 4 vs. 58 ± 2%, P = 0.04), but improved with tempol and apocynin (tempol: 58 ± 3 (P = 0.03), apocynin: 58 ± 4% (P = 0.03). Inhibition of xanthine oxidase did not alter cutaneous vasodilation in either group (P > 0.05). These data suggest that NAD(P)H oxidase is a source of reactive oxygen species and contributes to microvascular dysfunction in patients with CKD.

  7. Selection of functional human sperm with higher DNA integrity and fewer reactive oxygen species

    PubMed Central

    Asghar, Waseem; Velasco, Vanessa; Kingsley, James L.; Shoukat, Muhammad S.; Shafiee, Hadi; Anchan, Raymond M.; Mutter, George L.; Tüzel, Erkan; Demirci, Utkan

    2014-01-01

    Fertilization and reproduction are central to the survival and propagation of a species. Couples who cannot reproduce naturally have to undergo in vitro clinical procedures. An integral part of these clinical procedures includes isolation of healthy sperm from raw semen. Existing sperm sorting methods are not efficient and isolate sperm having high DNA fragmentation and reactive oxygen species, and suffer from multiple manual steps and variations between embryologists. Inspired by in vivo natural sperm sorting mechanisms where vaginal mucus becomes less viscous to form microchannels to guide sperm towards egg, we present a chip that efficiently sorts healthy, motile and morphologically normal sperm without centrifugation. Higher percentage of sorted sperm show significantly lesser reactive oxygen species and DNA fragmentation than the conventional swim-up method. The presented chip is an easy-to-use high throughput sperm sorter that provides standardized sperm sorting assay with less reliance on embryologist’s skills, facilitating reliable operational steps. PMID:24753434

  8. Palladium-Based Nanomaterials: A Platform to Produce Reactive Oxygen Species for Catalyzing Oxidation Reactions.

    PubMed

    Long, Ran; Huang, Hao; Li, Yaping; Song, Li; Xiong, Yujie

    2015-11-25

    Oxidation reactions by molecular oxygen (O2 ) over palladium (Pd)-based nanomaterials are a series of processes crucial to the synthesis of fine chemicals. In the past decades, investigations of related catalytic materials have mainly been focused on the synthesis of Pd-based nanomaterials from the angle of tailoring their surface structures, compositions and supporting materials, in efforts to improve their activities in organic reactions. From the perspective of rational materials design, it is imperative to address the fundamental issues associated with catalyst performance, one of which should be oxygen activation by Pd-based nanomaterials. Here, the fundamentals that account for the transformation from O2 to reactive oxygen species over Pd, with a focus on singlet O2 and its analogue, are introduced. Methods for detecting and differentiating species are also presented to facilitate future fundamental research. Key factors for tuning the oxygen activation efficiencies of catalytic materials are then outlined, and recent developments in Pd-catalyzed oxygen-related organic reactions are summarized in alignment with each key factor. To close, we discuss the challenges and opportunities for photocatalysis research at this unique intersection as well as the potential impact on other research fields.

  9. Free radical scavengers in anaesthesiology and critical care.

    PubMed

    Hatwalne, Milind S

    2012-05-01

    Free radicals are highly reactive and unstable compounds. These highly reactive molecules cause oxidative damage to cellular components such as DNA, proteins and lipids. They play central role in the mechanism of cell injury and cell death. Free radical scavengers either prevent these reactive species from being formed, or remove them before they can damage vital components of the cell. Oxidative stress defines an imbalance in production of oxidizing chemical species and their effective removal by protective antioxidants and scavenger enzymes. Evidence of massive oxidative stress is well established in critical illnesses characterized by tissue ischaemia-reperfusion injury and by an intense systemic inflammatory response such as during sepsis and acute respiratory distress syndrome, acute lung injury. Several clinical trials have been performed in order to reduce oxidative stress by supplementation of antioxidants alone or in combination with standard therapies. Antioxidant supplementation at an early stage of illness may lead to improved therapies in the treatment of critically ill patients. Several intravenous anaesthetic drugs act as reactive oxygen species scavengers. Anaesthetic preconditioning is of particular interest to anaesthesiologist, in which lasting protection of myocardium is elicited by brief exposure to a inhalational anaesthetic agent. These anasthetics may also mediate protective effects in other organs, such as the brain and kidney It is important for the anaesthesiologist to understand the mechanism of damage caused by free radicals and how free radical scavengers work so that this knowledge can be applied to varied pathological conditions. The topic was hand searched in text books and electronically searched from PubMed and Google scholar using text words.

  10. Oxygen stress reduces zoospore survival of Phytophthora species in a simulated aquatic system

    PubMed Central

    2014-01-01

    Background The genus Phytophthora includes a group of agriculturally important pathogens and they are commonly regarded as water molds. They produce motile zoospores that can move via water currents and on their own locomotion in aquatic environments. However, zoosporic response to dissolved oxygen, an important water quality parameter, is not known. Like other water quality parameters, dissolved oxygen concentration in irrigation reservoirs fluctuates dramatically over time. The aim of this study was to determine whether and how zoospore survival may be affected by elevated and low concentrations of dissolved oxygen in water to better understand the aquatic biology of these pathogens in irrigation reservoirs. Results Zoospores of P. megasperma, P. nicotianae, P. pini and P. tropicalis were assessed for survival in 10% Hoagland’s solution at a range of dissolved concentrations from 0.9 to 20.1 mg L-1 for up to seven exposure times from 0 to 72 h. Zoospore survival was measured by resultant colony counts per ml. Zoospores of these species survived the best in control Hoagland’s solution at dissolved oxygen concentrations of 5.3 to 5.6 mg L-1. Zoospore survival rates decreased with increasing and decreasing concentration of dissolved oxygen, depending upon Phytophthora species and exposure time. Overall, P. megasperma and P. pini are less sensitive than P. nicotianae and P. tropicalis to hyperoxia and hypoxia conditions. Conclusion Zoospores in the control solution declined over time and this natural decline process was enhanced under hyperoxia and hypoxia conditions. These findings suggest that dramatic fluctuations of dissolved oxygen in irrigation reservoirs contribute to the population decline of Phytophthora species along the water path in the same reservoirs. These findings advanced our understanding of the aquatic ecology of these pathogens in irrigation reservoirs. They also provided a basis for pathogen risk mitigation by prolonging the turnover

  11. Prostaglandins and radical oxygen species are involved in microvascular effects of hyperoxia.

    PubMed

    Rousseau, A; Tesselaar, E; Henricson, J; Sjöberg, F

    2010-01-01

    Hyperoxia causes vasoconstriction in most tissues, by mechanisms that are not fully understood. We investigated microvascular effects of breathing 100% oxygen in healthy volunteers, using iontophoresis to deliver acetylcholine (ACh) and sodium nitroprusside (SNP). Aspirin and vitamin C were used to test for involvement of prostaglandins and radical oxygen species. Forearm skin perfusion was measured using laser Doppler perfusion imaging. Results were analysed using dose-response modelling. The response to ACh was reduced by 30% during oxygen breathing compared to air breathing [0.98 (0.81-1.15) PU vs. 1.45 (1.30-1.60) PU, p < 0.001]. ED(50) values were unchanged [2.25 (1.84-2.75) vs. 2.21 (1.79-2.74), not significant]. Aspirin pre-treatment abolished the difference in response between oxygen breathing and air breathing [maximum: 1.03 (0.90-1.16) vs. 0.89 (0.77-1.01), not significant; ED(50): 1.83 (1.46-2.30) vs. 1.95 (1.65-2.30), not significant]. ACh-mediated vasodilatation during 100% oxygen breathing was partially restored after pre-treatment with vitamin C. Breathing 100% oxygen did not change the microvascular response to SNP [1.45 (1.28-1.62) vs. 1.40 (1.26-1.53), not significant]. These results favour the hypothesis that hyperoxic vasoconstriction is mediated by inhibition of prostaglandin synthesis. Radical oxygen species may be involved as vitamin C, independently of aspirin, partially restored ACh-mediated vasodilatation during hyperoxia.

  12. Crosstalk between nitrite, myoglobin and reactive oxygen species to regulate vasodilation under hypoxia.

    PubMed

    Totzeck, Matthias; Hendgen-Cotta, Ulrike B; Kelm, Malte; Rassaf, Tienush

    2014-01-01

    The systemic response to decreasing oxygen levels is hypoxic vasodilation. While this mechanism has been known for more than a century, the underlying cellular events have remained incompletely understood. Nitrite signaling is critically involved in vessel relaxation under hypoxia. This can be attributed to the presence of myoglobin in the vessel wall together with other potential nitrite reductases, which generate nitric oxide, one of the most potent vasodilatory signaling molecules. Questions remain relating to the precise concentration of nitrite and the exact dose-response relations between nitrite and myoglobin under hypoxia. It is furthermore unclear whether regulatory mechanisms exist which balance this interaction. Nitrite tissue levels were similar across all species investigated. We then investigated the exact fractional myoglobin desaturation in an ex vivo approach when gassing with 1% oxygen. Within a short time frame myoglobin desaturated to 58±12%. Given that myoglobin significantly contributes to nitrite reduction under hypoxia, dose-response experiments using physiological to pharmacological nitrite concentrations were conducted. Along all concentrations, abrogation of myoglobin in mice impaired vasodilation. As reactive oxygen species may counteract the vasodilatory response, we used superoxide dismutase and its mimic tempol as well as catalase and ebselen to reduce the levels of reactive oxygen species during hypoxic vasodilation. Incubation of tempol in conjunction with catalase alone and catalase/ebselen increased the vasodilatory response to nitrite. Our study shows that modest hypoxia leads to a significant nitrite-dependent vessel relaxation. This requires the presence of vascular myoglobin for both physiological and pharmacological nitrite levels. Reactive oxygen species, in turn, modulate this vasodilation response.

  13. Generation of reactive oxygen species by a novel berberine–bile acid analog mediates apoptosis in hepatocarcinoma SMMC-7721 cells

    SciTech Connect

    Li, Qingyong; Zhang, Li; Zu, Yuangang; Liu, Tianyu; Zhang, Baoyou; He, Wuna

    2013-04-19

    Graphical abstract: - Highlights: • Anticancer effects of B4, a novel berberine–bile acid analog, were tested. • B4 inhibited cell proliferation in hepatocellular carcinoma cells. • It also stimulated mitochondrial ROS production and membrane depolarization. • Effects of B4 were inhibited by a non-specific ROS scavenger. • Regulation of ROS generation may be a strategy for treating hepatic carcinoma. - Abstract: 2,3-Methenedioxy-9-O-(3′α,7′α-dihydroxy-5′β-cholan-24′-propy-lester) berberine (B4) is a novel berberine–bile acid analog synthesized in our laboratory. Previously, we showed that B4 exerted greater cytotoxicity than berberine in several human cancer cell lines. Therefore, we further evaluated the mechanism governing its anticancer actions in hepatocellular carcinoma SMMC-7721 cells. B4 inhibited the proliferation of SMMC-7721 cells, and stimulated reactive oxygen species (ROS) production and mitochondrial membrane depolarization; anti-oxidant capacity was reduced. B4 also induced the release of cytochrome c from the mitochondria to the cytosol and an increase in poly ADP-ribose polymerase (PARP) cleavage products, reflective of caspase-3 activation. Moreover, B4 induced the nuclear translocation of apoptosis-inducing factor (AIF) and a rise in DNA fragmentation. Pretreatment with the anti-oxidant N-acetylcysteine (NAC) inhibited B4-mediated effects, including cytotoxicity, ROS production, mitochondrial membrane depolarization increase in intracellular Ca{sup 2+}, cytochrome c release, PARP cleavage, and AIF translocation. Our data suggest that B4 induces ROS-triggered caspase-dependent and caspase-independent apoptosis pathways in SMMC-7721 cells and that ROS production may be a specific potential strategy for treating hepatic carcinoma.

  14. NADPH Oxidase-Derived Overproduction of Reactive Oxygen Species Impairs Postischemic Neovascularization in Mice with Type 1 Diabetes

    PubMed Central

    Ebrahimian, Téni G; Heymes, Christophe; You, Dong; Blanc-Brude, Olivier; Mees, Barend; Waeckel, Ludovic; Duriez, Micheline; Vilar, José; Brandes, Ralph P.; Levy, Bernard I.; Shah, Ajay M.; Silvestre, Jean-Sébastien

    2006-01-01

    We hypothesized that diabetes-induced oxidative stress may affect postischemic neovascularization. The response to unilateral femoral artery ligation was studied in wild-type or gp91phox-deficient control or type 1 diabetic mice or in animals treated with the anti-oxidant N-acetyl-l-cysteine (NAC) or with in vivo electrotransfer of a plasmid encoding dominant-negative Rac1 (50 μg) for 21 days. Postischemic neovascularization was reduced in diabetic mice in association with down-regulated vascular endothelial growth factor-A protein levels. In diabetic animals vascular endothelial growth factor levels and postischemic neovascularization were restored to nondiabetic levels by the scavenging of reactive oxygen species (ROS) by NAC administration or the inhibition of ROS generation by gp91phox deficiency or by administration of dominant-negative Rac1. Finally, diabetes reduced the ability of adherent bone marrow-derived mononuclear cells (BM-MNCs) to differentiate into endothelial progenitor cells. Treatment with NAC (3 mmol/L), apocynin (200 μmol/L), or the p38MAPK inhibitor LY333351 (10 μmol/L) up-regulated the number of endothelial progenitor cell colonies derived from diabetic BM-MNCs by 1.5-, 1.6-, and 1.5-fold, respectively (P < 0.05). In the ischemic hindlimb model, injection of diabetic BM-MNCs isolated from NAC-treated or gp91phox-deficient diabetic mice increased neovascularization by ∼1.5-fold greater than untreated diabetic BM-MNCs (P < 0.05). Thus, inhibition of NADPH oxidase-derived ROS overproduction improves the angiogenic and vasculogenic processes and restores postischemic neovascularization in type 1 diabetic mice. PMID:16877369

  15. NADPH oxidase-derived overproduction of reactive oxygen species impairs postischemic neovascularization in mice with type 1 diabetes.

    PubMed

    Ebrahimian, Téni G; Heymes, Christophe; You, Dong; Blanc-Brude, Olivier; Mees, Barend; Waeckel, Ludovic; Duriez, Micheline; Vilar, José; Brandes, Ralph P; Levy, Bernard I; Shah, Ajay M; Silvestre, Jean-Sébastien

    2006-08-01

    We hypothesized that diabetes-induced oxidative stress may affect postischemic neovascularization. The response to unilateral femoral artery ligation was studied in wild-type or gp91(phox)-deficient control or type 1 diabetic mice or in animals treated with the anti-oxidant N-acetyl-l-cysteine (NAC) or with in vivo electrotransfer of a plasmid encoding dominant-negative Rac1 (50 microg) for 21 days. Postischemic neovascularization was reduced in diabetic mice in association with down-regulated vascular endothelial growth factor-A protein levels. In diabetic animals vascular endothelial growth factor levels and postischemic neovascularization were restored to nondiabetic levels by the scavenging of reactive oxygen species (ROS) by NAC administration or the inhibition of ROS generation by gp91(phox) deficiency or by administration of dominant-negative Rac1. Finally, diabetes reduced the ability of adherent bone marrow-derived mononuclear cells (BM-MNCs) to differentiate into endothelial progenitor cells. Treatment with NAC (3 mmol/L), apocynin (200 micromol/L), or the p38MAPK inhibitor LY333351 (10 micromol/L) up-regulated the number of endothelial progenitor cell colonies derived from diabetic BM-MNCs by 1.5-, 1.6-, and 1.5-fold, respectively (P < 0.05). In the ischemic hindlimb model, injection of diabetic BM-MNCs isolated from NAC-treated or gp91(phox)-deficient diabetic mice increased neovascularization by approximately 1.5-fold greater than untreated diabetic BM-MNCs (P < 0.05). Thus, inhibition of NADPH oxidase-derived ROS overproduction improves the angiogenic and vasculogenic processes and restores postischemic neovascularization in type 1 diabetic mice.

  16. Pleiotrophin-induced endothelial cell migration is regulated by xanthine oxidase-mediated generation of reactive oxygen species.

    PubMed

    Tsirmoula, Sotiria; Lamprou, Margarita; Hatziapostolou, Maria; Kieffer, Nelly; Papadimitriou, Evangelia

    2015-03-01

    Pleiotrophin (PTN) is a heparin-binding growth factor that induces cell migration through binding to its receptor protein tyrosine phosphatase beta/zeta (RPTPβ/ζ) and integrin alpha v beta 3 (ανβ3). In the present work, we studied the effect of PTN on the generation of reactive oxygen species (ROS) in human endothelial cells and the involvement of ROS in PTN-induced cell migration. Exogenous PTN significantly increased ROS levels in a concentration and time-dependent manner in both human endothelial and prostate cancer cells, while knockdown of endogenous PTN expression in prostate cancer cells significantly down-regulated ROS production. Suppression of RPTPβ/ζ through genetic and pharmacological approaches, or inhibition of c-src kinase activity abolished PTN-induced ROS generation. A synthetic peptide that blocks PTN-ανβ3 interaction abolished PTN-induced ROS generation, suggesting that ανβ3 is also involved. The latter was confirmed in CHO cells that do not express β3 or over-express wild-type β3 or mutant β3Y773F/Y785F. PTN increased ROS generation in cells expressing wild-type β3 but not in cells not expressing or expressing mutant β3. Phosphoinositide 3-kinase (PI3K) or Erk1/2 inhibition suppressed PTN-induced ROS production, suggesting that ROS production lays down-stream of PI3K or Erk1/2 activation by PTN. Finally, ROS scavenging and xanthine oxidase inhibition completely abolished both PTN-induced ROS generation and cell migration, while NADPH oxidase inhibition had no effect. Collectively, these data suggest that xanthine oxidase-mediated ROS production is required for PTN-induced cell migration through the cell membrane functional complex of ανβ3 and RPTPβ/ζ and activation of c-src, PI3K and ERK1/2 kinases.

  17. Curcumin induces ER stress-mediated apoptosis through selective generation of reactive oxygen species in cervical cancer cells.

    PubMed

    Kim, Boyun; Kim, Hee Seung; Jung, Eun-Ji; Lee, Jung Yun; K Tsang, Benjamin; Lim, Jeong Mook; Song, Yong Sang

    2016-05-01

    Prolonged accumulation of misfolded or unfolded proteins caused by cellular stress, including oxidative stress, induces endoplasmic reticulum stress, which then activates an unfolded protein response (UPR). ER stress is usually maintained at higher levels in cancer cells as compared to normal cells due to altered metabolism in cancer. Here, we investigated whether curcumin is ER stress-mediated apoptosis in cervical cancer cells, and ROS increased by curcumin are involved in the process as an upstream contributor. Curcumin inhibited proliferation of cervical cancer cells (C33A, CaSki, HeLa, and ME180) and induced apoptotic cell death. Curcumin activated ER-resident UPR sensors, such as PERK, IRE-1α, and ATF6, and their downstream-signaling proteins in cervical cancer cells, but not in normal epithelial cells and peripheral blood mononuclear cells (PBMCs). CHOP, a key factor involved in ER stress-mediated apoptosis, was also activated by curcumin. CHOP decreased the ratio of anti-apoptotic protein Bcl-2 to pro-apoptotic protein Bax expression, and subsequently increased the apoptotic population of cervical cancer cells. Furthermore, curcumin elevated levels of intracellular reactive oxygen species (ROS) in cervical cancer cells, but not in normal epithelial cells. Scavenging ROS resulted in inhibition of ER stress and partially restored cell viability in curcumin-treated cancer cells. Collectively, these observations show that curcumin promotes ER stress-mediated apoptosis in cervical cancer cells through increase of cell type-specific ROS generation. Therefore, modulation of these differential responses to curcumin between normal and cervical cancer cells could be an effective therapeutic strategy without adverse effects on normal cells.

  18. Aging increases the susceptivity of MSCs to reactive oxygen species and impairs their therapeutic potency for myocardial infarction.

    PubMed

    Li, Liang; Guo, Yingfei; Zhai, Hongxia; Yin, Yaxin; Zhang, Jinjin; Chen, Haiwei; Wang, Lei; Li, Na; Liu, Runmei; Xia, Yunfeng

    2014-01-01

    Myocardial infarction (MI) is one of the leading causes of death worldwide and Mesenchymal Stem Cells (MSCs) transplantation has been considered a promising therapy. Recently, it was reported that the therapeutic effectiveness of MSCs is dependent on the age of the donor, yet the underlying mechanism has not been thoroughly investigated. This study was designed to investigate whether this impaired therapeutic potency is caused by an increased susceptivity of MSCs from old donors to reactive oxygen species (ROS). The MSCs were isolated from the subcutaneous inguinal region of young (8-10 weeks) and old (18 months) Sprague-Dawley (SD) rats. By exposing these MSCs to H2O2, we found that the adhesion of MSCs from old donors was damaged more severely. Specifically, decreased expression of integrin and reduced phosphorylation of focal adhesion kinase Src and FAK were observed. Furthemore, H2O2 triggered an increased apoptosis of MSCs from old donors. To study the viability and therapeutic potency of MSCs from young and old donors in vivo, these MSCs were transplanted into acute MI model rats. We observed a more rapidly decreased survival rate of the old MSCs in the infarct region, which may be caused by their increased susceptivity to the micro-environmental ROS, as transplantation of the old MSCs with N-acetyl-L-cysteine (NAC), a ROS scavenger, protected them. The low viability of engrafted old MSCs consequently impaired their therapeutic effectiveness, judging by the histology and function of heart. Our study may help to understand the mechanism of MSCs-host interaction during MI, as well as shed light on the design of therapeutic strategy in clinic.

  19. Green tea extract protects endothelial progenitor cells from oxidative insult through reduction of intracellular reactive oxygen species activity

    PubMed Central

    Widowati, Wahyu; Widyanto, Rahma Micho; Husin, Winsa; Ratnawati, Hana; Laksmitawati, Dian Ratih; Setiawan, Bambang; Nugrahenny, Dian; Bachtiar, Indra

    2014-01-01

    Objective(s): Many studies have reported that tea consumption decreases cardiovascular risk, but the mechanisms remain unclear. Green tea is known to have potent antioxidant and free radical scavenging activities. This study aimed to investigate whether green tea extract (GTE) can protect endothelial progenitors cells (EPCs) against oxidative stress through antioxidant mechanisms. Materials and Methods: Mononuclear cells (MNCs) were isolated from peripheral blood by density gradient centrifugation with Ficoll. The cells were then plated on fibronectin-coated culture dishes. After 7 days of culture, EPCs were characterized as adherent cells double positive for DiI-ac-LDL uptake and lectin binding. EPCs were further identified by assessing the expression of CD34/45, CD133, and KDR. EPCs were then treated with hydrogen peroxide (H2O2) at doses of 50, 100, 200 µM and incubated with or without GTE (25 µg/ml). The intracellular reactive oxygen species (ROS) levels were detected by flow cytometry using a 2',7'-dichlorofluorescein diacetate (DCF-DA) fluorescent probe. Results: GTE ameliorated the cell viability of EPCs induced by H2O2 at doses of 50, 100, 200 µM for about 25.47, 22.52, and 11.96% higher than controls, respectively. GTE also decreased the intracellular ROS levels of EPCs induced by H2O2 at doses of 50, 100, 200 µM for about 84.24, 92.27, and 93.72% compared to controls, respectively. Conclusion: GTE improves cell viability by reducing the intracellular ROS accumulation in H2O2-induced EPCs. PMID:25691948

  20. 2,5-hexanedione induced apoptosis of rat bone marrow mesenchymal stem cells by reactive oxygen species

    PubMed Central

    Liu, Shuang; Chen, Feng; Wang, Longjuan; Sun, Wenchang; Liu, Qigui; Chen, Haibo; Su, Dan; Jiang, Yue; Piao, Fengyuan; Sun, Xiance; Sun, Wenfang

    2016-01-01

    Objectives: n-Hexane, a common industrial organic solvent, causes multiple organ damage, especially neurotoxicity, which is proved to be caused by its metabolite 2,5-hexanedione (2,5-HD). We previously showed that 2,5-HD induced apoptosis of rat bone marrow mesenchymal stem cells (BMSCs). In the current study, we explored the mechanism of 2,5-HD-induced apoptosis, especially the role played by reactive oxygen species (ROS). Methods: Intracellular ROS levels after 2,5-HD treatment were measured by the dichloro-dihydro-fluorescein diacetate (DCFH-DA) method, and the antioxidant N-acetyl cysteine (NAC) was used to scavenge ROS. Apoptosis, mitochondrial membrane potential (MMP), and caspase-3 activity were measured after 2,5-HD exposure with or without NAC pretreatment. Results: In rat BMSCs, 20 mM 2,5-HD significantly increased ROS levels and apoptosis. In addition, MMP activity was decreased and caspase-3 activity was increased. With NAC pretreatment, ROS increases were prevented, cells were rescued from apoptosis, and both MMP and caspase-3 activity returned to normal levels. Western blotting analysis of malondialdehyde-modified proteins and superoxide dismutase (SOD) 1 showed that after 2,5-HD exposure, BMSCs had oxidative damage and abnormal SOD1 expression. These returned to normal when cells were pretreated with NAC in addition to 20 mM 2,5-HD. Furthermore, the expressions of NF-κB p65/RelA and phospho-NF-κB p65/RelA (Ser536) were suppressed after 2,5-HD exposure and restored by NAC pretreatment. Conclusions: 2,5-HD-induced apoptosis in rat BMSCs is potentially mediated by excessive ROS production. PMID:27010086

  1. Osimertinib induces autophagy and apoptosis via reactive oxygen species generation in non-small cell lung cancer cells.

    PubMed

    Tang, Zheng-Hai; Cao, Wen-Xiang; Su, Min-Xia; Chen, Xiuping; Lu, Jin-Jian

    2017-04-15

    Osimertinib (OSI), also known as AZD9291, is a third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor that has been approved for the treatment of non-small cell lung cancer (NSCLC) patients harboring EGFR T790M mutation. Herein, we indicated for the first time that OSI increased the accumulations of cytoplasmic vacuoles, the expression of phosphatidylethanolamine-modified microtubule-associated protein light-chain 3 (LC3-II), and the formation of GFP-LC3 puncta in various cancer cells. The OSI-induced expression of LC3-II was further increased when combined treatment with chloroquine (CQ), an autophagy inhibitor, and the mRFP-EGFP-LC3 plasmid-transfected cells exposed to OSI led to the production of more red-fluorescent puncta than green-fluorescent puncta, indicating OSI induced autophagic flux in the NSCLC cells. Knockdown of EGFR showed no effect on the OSI-induced expression of LC3-II in NCI-H1975 cells. In addition, OSI increased reactive oxygen species (ROS) generation and scavenge of ROS via pretreatment with N-acetyl-l-cysteine (NAC), catalase (CAT), or vitamin E (Vita E) significantly inhibited OSI-induced the accumulations of cytoplasmic vacuoles, the expression of LC3-II, as well as the formation of GFP-LC3 puncta. Combinative treatment with CQ could not remarkably change the OSI-induced cell viability decrease, whereas the OSI-induced cell viability decrease and apoptosis could be reversed through pretreatment with NAC, CAT, and Vita E, respectively. Taken together, this is the first report that OSI induces an accompanied autophagy and the generation of ROS is critical for the OSI-induced autophagy, cell viability decrease, and apoptosis in NSCLC cells.

  2. Inhibition of mitochondrial protein translation sensitizes melanoma cells to arsenic trioxide cytotoxicity via a reactive oxygen species dependent mechanism

    PubMed Central

    Bowling, Benjamin D.; Doudican, Nicole; Manga, Prashiela; Orlow, Seth J.

    2009-01-01

    Purpose Current standard chemotherapeutic regimens for malignant melanoma are unsatisfactory. Although in vitro studies of arsenic trioxide (ATO) have demonstrated promise against melanoma, recent phase II clinical trials have failed to show any significant clinical benefit when used as a single agent. To enhance the efficacy of ATO in the treatment of melanoma, we sought to identify compounds that potentiate the cytotoxic effects of ATO in melanoma cells. Through a screen of 2000 marketed drugs and naturally occurring compounds, a variety of antibiotic inhibitors of mitochondrial protein translation were identified. Methods The mechanism of action for the most effective agent identified, thiostrepton, was examined in a panel of melanoma cells. Effects of combinatorial ATO and thiostrepton treatment on cytotoxicity, apoptosis, mitochondrial protein content, and reactive oxygen species (ROS) were assessed. Results Thiostrepton (1μM) sensitized 3 out of 5 melanoma cell lines to ATO-mediated growth inhibition. Treatment with thiostrepton resulted in reduced levels of the mitochondrial-encoded protein cytochrome oxidase I (COX1). Exposure to thiostrepton in combination with ATO resulted in increased levels of cleaved poly (ADP-ribose) polymerase and cellular ROS. The growth inhibitory and pro-apototic effects of addition of the ATO/thiostrepton combination were reversed by the free radical scavenger N-acetyl-l-cysteine. Conculsions Our data suggest that thiostrepton enhances the cytotoxic effects of ATO through a ROS-dependent mechanism. Co-administration of oxidative stress-inducing drugs such as thiostrepton in order to enhance the efficacy of ATO in the treatment of melanoma warrants further investigation. PMID:18297286

  3. Involvement of reactive oxygen species in endosperm cap weakening and embryo elongation growth during lettuce seed germination.

    PubMed

    Zhang, Yu; Chen, Bingxian; Xu, Zhenjiang; Shi, Zhaowan; Chen, Shanli; Huang, Xi; Chen, Jianxun; Wang, Xiaofeng

    2014-07-01

    Endosperm cap (CAP) weakening and embryo elongation growth are prerequisites for the completion of lettuce seed germination. Although it has been proposed that the cell wall loosening underlying these processes results from an enzymatic mechanism, it is still unclear which enzymes are involved. Here it is shown that reactive oxygen species (ROS), which are non-enzymatic factors, may be involved in the two processes. In Guasihong lettuce seeds imbibed in water, O2·(-) and H2O2 accumulated and peroxidase activity increased in the CAP, whereas its puncture force decreased. In addition, in the radicle, the increase in embryo growth potential was accompanied by accumulation of O2·(-) and an increase in peroxidase activity. Imbibing seeds in 0.3% sodium dichloroisocyanurate (SDIC) reduced endosperm viability and the levels of O2·(-), H2O2, and peroxidase activity in the CAP, whereas the decrease in its puncture force was inhibited. However, in the embryo, SDIC did not affect the accumulation of O2·(-), peroxidase activity, and the embryo growth potential. As a result, SDIC caused atypical germination, in which the endosperm ruptured at the boundary between the CAP and lateral endosperm. ROS scavengers and ROS generation inhibitors inhibited the CAP weakening and also decreased the embryo growth potential, thus decreasing the percentage of seed germination. Exogenous ROS and ROS generation inducers increased the percentage of CAP rupture to some extent, and the addition of H2O2 to 0.3% SDIC enabled some seeds to undergo typical germination.

  4. Apoptosis induction by silica nanoparticles mediated through reactive oxygen species in human liver cell line HepG2

    SciTech Connect

    Ahmad, Javed; Ahamed, Maqusood; Akhtar, Mohd Javed; Alrokayan, Salman A.; Siddiqui, Maqsood A.; Musarrat, Javed; Al-Khedhairy, Abdulaziz A.

    2012-03-01

    Silica nanoparticles are increasingly utilized in various applications including agriculture and medicine. In vivo studies have shown that liver is one of the primary target organ of silica nanoparticles. However, possible mechanisms of hepatotoxicity caused by silica nanoparticles still remain unclear. In this study, we explored the reactive oxygen species (ROS) mediated apoptosis induced by well-characterized 14 nm silica nanoparticles in human liver cell line HepG2. Silica nanoparticles (25–200 μg/ml) induced a dose-dependent cytotoxicity in HepG2 cells. Silica nanoparticles were also found to induce oxidative stress in dose-dependent manner indicated by induction of ROS and lipid peroxidation and depletion of glutathione (GSH). Quantitative real-time PCR and immunoblotting results showed that both the mRNA and protein expressions of cell cycle checkpoint gene p53 and apoptotic genes (bax and caspase-3) were up-regulated while the anti-apoptotic gene bcl-2 was down-regulated in silica nanoparticles treated cells. Moreover, co-treatment of ROS scavenger vitamin C significantly attenuated the modulation of apoptotic markers along with the preservation of cell viability caused by silica nanoparticles. Our data demonstrated that silica nanoparticles induced apoptosis in human liver cells, which is ROS mediated and regulated through p53, bax/bcl-2 and caspase pathways. This study suggests that toxicity mechanisms of silica nanoparticles should be further investigated at in vivo level. -- Highlights: ► We explored the mechanisms of toxicity caused by silica NPs in human liver HepG2 cells. ► Silica NPs induced a dose-dependent cytotoxicity in HepG2 cells. ► Silica NPs induced ROS generation and oxidative stress in a dose-dependent manner. ► Silica NPs were also modulated apoptosis markers both at mRNA and protein levels. ► ROS mediated apoptosis induced by silica NPs was preserved by vitamin C.

  5. Nitric Oxide and Reactive Oxygen Species Coordinately Regulate the Germination of Puccinia striiformis f. sp. tritici Urediniospores

    PubMed Central

    Yin, Shuining; Gao, Zhijuan; Wang, Chenfang; Huang, Lili; Kang, Zhensheng; Zhang, Hongchang

    2016-01-01

    Nitric oxide (NO) and reactive oxygen species (ROS) function as signaling molecules in a number of critical signal transduction pathways in plants, including plant biotic interactions. In addition to the role of plant-derived NO and ROS in plant resistance, which has been well documented, pathogen-produced NO and ROS have recently emerged as important players in fungal development and pathogenesis. However, the effects of pathogenic fungi-derived NO and ROS on signaling pathways during fungal pre-infection development remain unknown. Here, using a combination of pharmacological approaches and confocal microscopy, we investigated the roles of NO and ROS during the germination of Puccinia striiformis Westend f. sp. tritici (Pst) the wheat stripe rust pathogen. Both NO and ROS have a crucial role in uredinial germination. The scavengers of NO and ROS delayed spore germination and decreased the lengths of germ tubes. A similar phenotype was produced after treatment with the promoter. However, the spores germinated and grew normally when the levels of NO and ROS were simultaneously elevated by the application of a promoter of NO and a donor of ROS. Confocal laser microscopy indicated that both NO and ROS preferentially localized at the germ pores and apexes of growing germ tubes when the ROS/NO ratio in the spores was maintained in a specific range. We concluded that both NO and ROS are critical signaling molecules in the pre-infection development of Pst and that the polar growth of the germ tube is coordinately regulated by NO and ROS. PMID:26941716

  6. Iron-induced reactive oxygen species mediate transporter DMT1 endocytosis and iron uptake in intestinal epithelial cells.

    PubMed

    Esparza, Andrés; Gerdtzen, Ziomara P; Olivera-Nappa, Alvaro; Salgado, J Cristian; Núñez, Marco T

    2015-10-15

    Recent evidence shows that iron induces the endocytosis of the iron transporter dimetal transporter 1 (DMT1) during intestinal absorption. We, and others, have proposed that iron-induced DMT1 internalization underlies the mucosal block phenomena, a regulatory response that downregulates intestinal iron uptake after a large oral dose of iron. In this work, we investigated the participation of reactive oxygen species (ROS) in the establishment of this response. By means of selective surface protein biotinylation of polarized Caco-2 cells, we determined the kinetics of DMT1 internalization from the apical membrane after an iron challenge. The initial decrease in DMT1 levels in the apical membrane induced by iron was followed at later times by increased levels of DMT1. Addition of Fe(2+), but not of Cd(2+), Zn(2+), Cu(2+), or Cu(1+), induced the production of intracellular ROS, as detected by 2',7'-dichlorofluorescein (DCF) fluorescence. Preincubation with the antioxidant N-acetyl-l-cysteine (NAC) resulted in increased DMT1 at the apical membrane before and after addition of iron. Similarly, preincubation with the hydroxyl radical scavenger dimethyl sulfoxide (DMSO) resulted in the enhanced presence of DMT1 at the apical membrane. The decrease of DMT1 levels at the apical membrane induced by iron was associated with decreased iron uptake rates. A kinetic mathematical model based on operational rate constants of DMT1 endocytosis and exocytosis is proposed. The model qualitatively captures the experimental observations and accurately describes the effect of iron, NAC, and DMSO on the apical distribution of DMT1. Taken together, our data suggest that iron uptake induces the production of ROS, which modify DMT1 endocytic cycling, thus changing the iron transport activity at the apical membrane.

  7. Cadmium toxicity in Maize (Zea mays L.): consequences on antioxidative systems, reactive oxygen species and cadmium accumulation.

    PubMed

    Anjum, Shakeel Ahmad; Tanveer, Mohsin; Hussain, Saddam; Bao, Mingchen; Wang, Longchang; Khan, Imran; Ullah, Ehsan; Tung, Shahbaz Atta; Samad, Rana Abdul; Shahzad, Babar

    2015-11-01

    Increased cadmium (Cd) accumulation in soils has led to tremendous environmental problems, with pronounced effects on agricultural productivity. Present study investigated the effects of Cd stress imposed at various concentrations (0, 75, 150, 225, 300, 375 μM) on antioxidant activities, reactive oxygen species (ROS), Cd accumulation, and productivity of two maize (Zea mays L.) cultivars viz., Run Nong 35 and Wan Dan 13. Considerable variations in Cd accumulation and in behavior of antioxidants and ROS were observed under Cd stress in both maize cultivars, and such variations governed by Cd were concentration dependent. Exposure of plant to Cd stress considerably increased Cd concentration in all plant parts particularly in roots. Wan Dan 13 accumulated relatively higher Cd in root, stem, and leaves than Run Nong 35; however, in seeds, Run Nong 35 recorded higher Cd accumulation. All the Cd toxicity levels starting from 75 μM enhanced H2O2 and MDA concentrations and triggered electrolyte leakage in leaves of both cultivars, and such an increment was more in Run Nong 35. The ROS were scavenged by the enhanced activities of superoxide dismutase, peroxidase, catalase, ascorbate peroxidase, and glutathione peroxidase in response to Cd stress, and these antioxidant activities were higher in Wan Dan 13 compared with Run Nong 35 at all Cd toxicity levels. The grain yield of maize was considerably reduced particularly for Run Nong 35 under different Cd toxicity levels as compared with control. The Wan Dan 13 was better able to alleviate Cd-induced oxidative damage which was attributed to more Cd accumulation in roots and higher antioxidant activities in this cultivar, suggesting that manipulation of these antioxidants and enhancing Cd accumulation in roots may lead to improvement in Cd stress tolerance.

  8. Scavenging of atmospheric constituents in mixed phase clouds at the high-alpine site jungfraujoch—part II. Influence of riming on the scavenging of particulate and gaseous chemical species

    NASA Astrophysics Data System (ADS)

    Poulida, O.; Schwikowski, M.; Baltensperger, U.; Staehelin, J.; Gaeggeler, H. W.

    The importance of riming as transfer mechanism of pollutants from the atmosphere into the snow in mixed phase clouds was investigated at the Jungfraujoch (3450 m a.s.l), during two intensive measurement campaigns in April 1992 and in October-November 1993. Cloud water and bulk snow crystal samples were concurrently collected during precipitation events, and were chromatographically analyzed for inorganic ions. The extent of riming was determined from the collection of individual snow crystals on Formvar replicas. Relatively low degrees of riming were observed during all the events. The rimed mass fraction (RMF) was being used as a tool to determine the role of riming with respect to other scavenging processes. No significant difference between the early-spring and the early-winter events was found. The precipitation events were classified on the basis of the temporal changes of the number concentration of aerosol particles and the equivalent potential temperature during an event. When the site could be considered as a "closed system", meaning that there was no air mass change, and that all the physical processes were occurring in the air mass being sampled at the site, then a strong positive correlation between the RMF and the concentration ratios, R, of snow water to cloud water was found. In contrast, a lack of statistical correlation between the RMF and the ratios R was observed when the sampling site was an "open system", meaning that it was affected by the entrainment of a new air mass. The application of a simple physical scheme revealed that a linear relationship between RMF and R is expected, provided that the cloud water samples are representative of the air mass in which the snow crystals are generated. Further modification of this scheme provided a relationship for the assessment of the importance of riming as transfer mechanism. The riming process was found to be responsible for 82 (±17) % of Cl -, 49 (±31) % of NO- 3, 77 (±20) % of SO 2-4, 82 (±16

  9. Quantum dot-mediated photoproduction of reactive oxygen species for cancer cell annihilation.

    PubMed

    Chen, Ji-Yao; Lee, Yee-Man; Zhao, Dan; Mak, Nai-Ki; Wong, Ricky Ngok-Shun; Chan, Wing-Hong; Cheung, Nai-Ho

    2010-01-01

    While semiconductor quantum dots produce little singlet oxygen, they may undergo Type I photoreactions to produce other reactive oxygen species (ROS) to kill cells. CdTe quantum dots coated with thioglycolic acid were used to test that possibility. Some thiol ligands were purposely removed to regenerate the surface electron traps that were passivated by the ligand. This allowed photoinduced electrons to dwell on the surface long enough to be gathered by nearby oxygen molecules to produce ROS. The photocytotoxicity of these quantum dots was tested on nasopharyngeal carcinoma cells. Photokilling was shown to be drug and light dose dependent. Using 0.6 mum quantum dots for incubation and 4.8 J cm(-2) for irradiation, about 80% of the cells were annihilated. These quantum dots promised to be potent sensitizers for photoannihilation of cancer cells.

  10. Standardizing scavenger receptor nomenclature.

    PubMed

    Prabhudas, Mercy; Bowdish, Dawn; Drickamer, Kurt; Febbraio, Maria; Herz, Joachim; Kobzik, Lester; Krieger, Monty; Loike, John; Means, Terry K; Moestrup, Soren K; Post, Steven; Sawamura, Tatsuya; Silverstein, Samuel; Wang, Xiang-Yang; El Khoury, Joseph

    2014-03-01

    Scavenger receptors constitute a large family of proteins that are structurally diverse and participate in a wide range of biological functions. These receptors are expressed predominantly by myeloid cells and recognize a variety of ligands, including endogenous and modified host-derived molecules and microbial pathogens. There are currently eight classes of scavenger receptors, many of which have multiple names, leading to inconsistencies and confusion in the literature. To address this problem, a workshop was organized by the U.S. National Institute of Allergy and Infectious Diseases, National Institutes of Health to help develop a clear definition of scavenger receptors and a standardized nomenclature based on that definition. Fifteen experts in the scavenger receptor field attended the workshop and, after extensive discussion, reached a consensus regarding the definition of scavenger receptors and a proposed scavenger receptor nomenclature. Scavenger receptors were defined as cell surface receptors that typically bind multiple ligands and promote the removal of non-self or altered-self targets. They often function by mechanisms that include endocytosis, phagocytosis, adhesion, and signaling that ultimately lead to the elimination of degraded or harmful substances. Based on this definition, nomenclature and classification of these receptors into 10 classes were proposed. The discussion and nomenclature recommendations described in this report only refer to mammalian scavenger receptors. The purpose of this article is to describe the proposed mammalian nomenclature and classification developed at the workshop and to solicit additional feedback from the broader research community.

  11. Botanical Scavenger Hunt

    ERIC Educational Resources Information Center

    Walker-Livingston, Wendy

    2009-01-01

    Why not combine the use of technology with the excitement of a scavenger hunt that moves middle-level students out into the "wilds" of their school campus to classify plants? In the lesson plan described here, students embark on a botanical scavenger hunt and then document their findings using a digital camera. This project was designed to allow…

  12. Scavenging of oxygen from SrTiO3 during oxide thin film deposition and the formation of interfacial 2DEGs

    NASA Astrophysics Data System (ADS)

    Posadas, Agham B.; Kormondy, Kristy J.; Guo, Wei; Ponath, Patrick; Geler-Kremer, Jacqueline; Hadamek, Tobias; Demkov, Alexander A.

    2017-03-01

    SrTiO3 is a widely used substrate for the growth of other functional oxide thin films. The reactivity of the substrate with respect to the film during deposition, particularly with regard to redox reactions, has typically been glossed over. We demonstrate by depositing a variety of metals (Ti, Al, Nb, Pt, Eu, and Sr) and measuring the in situ core level spectra of both the metal and SrTiO3 that, depending on the oxide formation energy and work function of the metal, three distinct types of behavior occur in thin metal films on SrTiO3 (100). In many cases, there will be an interfacial layer of oxygen-deficient SrTiO3 formed at the interface with the overlying film. We discuss how this may affect the interpretation of the well-known two-dimensional electron gas present at the interface between SrTiO3 and various oxides.

  13. Cytochrome P450 Reductase: A Harbinger of Diffusible Reduced Oxygen Species

    PubMed Central

    Manoj, Kelath Murali; Gade, Sudeep Kumar; Mathew, Lazar

    2010-01-01

    The bi-enzymatic system of cytochrome P450 (CYP, a hemoprotein) and cytochrome P450 reductase (CPR, a diflavoenzyme) mediate the redox metabolism of diverse indigenous and xenobiotic molecules in various cellular and organ systems, using oxygen and NADPH. Curiously, when a 1∶1 ratio is seen to be optimal for metabolism, the ubiquitous CYP:CPR distribution ratio is 10 to 100∶1 or higher. Further, the NADPH equivalents consumed in these in vitro or in situ assemblies usually far exceeded the amount of substrate metabolized. We aimed to find the rationale to explain for these two oddities. We report here that CPR is capable of activating molecular oxygen on its own merit, generating diffusible reduced oxygen species (DROS). Also, in the first instance for a flavoprotein, CPR is shown to deplete peroxide via diffusible radical mediated process, thereby leading to the formation of water (but without significant evolution of oxygen). We also quantitatively demonstrate that the rate of oxygen activation and peroxide depletion by CPR accounts for the major reactivity in the CYP+CPR mixture. We show unambiguously that CPR is able to regulate the concentration of diffusible reduced oxygen species in the reaction milieu. These findings point out that CPR mediated processes are bound to be energetically ‘wasteful’ and potentially ‘hazardous’ owing to the unavoidable nature of the CPR to generate and deplete DROS. Hence, we can understand that CPR is distributed at low densities in cells. Some of the activities that were primarily attributed to the heme-center of CYP are now established to be a facet of the flavins of CPR. The current approach of modeling drugs to minimize “uncoupling” on the basis of erstwhile hypothesis stands questionable, considering the ideas brought forth in this work. PMID:20967245

  14. REACTOR FUEL SCAVENGING MEANS

    DOEpatents

    Coffinberry, A.S.

    1962-04-10

    A process for removing fission products from reactor liquid fuel without interfering with the reactor's normal operation or causing a significant change in its fuel composition is described. The process consists of mixing a liquid scavenger alloy composed of about 44 at.% plutoniunm, 33 at.% lanthanum, and 23 at.% nickel or cobalt with a plutonium alloy reactor fuel containing about 3 at.% lanthanum; removing a portion of the fuel and scavenger alloy from the reactor core and replacing it with an equal amount of the fresh scavenger alloy; transferring the portion to a quiescent zone where the scavenger and the plutonium fuel form two distinct liquid layers with the fission products being dissolved in the lanthanum-rich scavenger layer; and the clean plutonium-rich fuel layer being returned to the reactor core. (AEC)

  15. Identification of different oxygen species in oxide nanostructures with 17O solid-state NMR spectroscopy

    PubMed Central

    Wang, Meng; Wu, Xin-Ping; Zheng, Sujuan; Zhao, Li; Li, Lei; Shen, Li; Gao, Yuxian; Xue, Nianhua; Guo, Xuefeng; Huang, Weixin; Gan, Zhehong; Blanc, Frédéric; Yu, Zhiwu; Ke, Xiaokang; Ding, Weiping; Gong, Xue-Qing; Grey, Clare P.; Peng, Luming

    2015-01-01

    Nanostructured oxides find multiple uses in a diverse range of applications including catalysis, energy storage, and environmental management, their higher surface areas, and, in some cases, electronic properties resulting in different physical properties from their bulk counterparts. Developing structure-property relations for these materials requires a determination of surface and subsurface structure. Although microscopy plays a critical role owing to the fact that the volumes sampled by such techniques may not be representative of the whole sample, complementary characterization methods are urgently required. We develop a simple nuclear magnetic resonance (NMR) strategy to detect the first few layers of a nanomaterial, demonstrating the approach with technologically relevant ceria nanoparticles. We show that the 17O resonances arising from the first to third surface layer oxygen ions, hydroxyl sites, and oxygen species near vacancies can be distinguished from the oxygen ions in the bulk, with higher-frequency 17O chemical shifts being observed for the lower coordinated surface sites. H217O can be used to selectively enrich surface sites, allowing only these particular active sites to be monitored in a chemical process. 17O NMR spectra of thermally treated nanosized ceria clearly show how different oxygen species interconvert at elevated temperature. Density functional theory calculations confirm the assignments and reveal a strong dependence of chemical shift on the nature of the surface. These results open up new strategies for characterizing nanostructured oxides and their applications. PMID:26601133

  16. Identification of different oxygen species in oxide nanostructures with (17)O solid-state NMR spectroscopy.

    PubMed

    Wang, Meng; Wu, Xin-Ping; Zheng, Sujuan; Zhao, Li; Li, Lei; Shen, Li; Gao, Yuxian; Xue, Nianhua; Guo, Xuefeng; Huang, Weixin; Gan, Zhehong; Blanc, Frédéric; Yu, Zhiwu; Ke, Xiaokang; Ding, Weiping; Gong, Xue-Qing; Grey, Clare P; Peng, Luming

    2015-02-01

    Nanostructured oxides find multiple uses in a diverse range of applications including catalysis, energy storage, and environmental management, their higher surface areas, and, in some cases, electronic properties resulting in different physical properties from their bulk counterparts. Developing structure-property relations for these materials requires a determination of surface and subsurface structure. Although microscopy plays a critical role owing to the fact that the volumes sampled by such techniques may not be representative of the whole sample, complementary characterization methods are urgently required. We develop a simple nuclear magnetic resonance (NMR) strategy to detect the first few layers of a nanomaterial, demonstrating the approach with technologically relevant ceria nanoparticles. We show that the (17)O resonances arising from the first to third surface layer oxygen ions, hydroxyl sites, and oxygen species near vacancies can be distinguished from the oxygen ions in the bulk, with higher-frequency (17)O chemical shifts being observed for the lower coordinated surface sites. H2 (17)O can be used to selectively enrich surface sites, allowing only these particular active sites to be monitored in a chemical process. (17)O NMR spectra of thermally treated nanosized ceria clearly show how different oxygen species interconvert at elevated temperature. Density functional theory calculations confirm the assignments and reveal a strong dependence of chemical shift on the nature of the surface. These results open up new strategies for characterizing nanostructured oxides and their applications.

  17. Probing oxidative stress: Small molecule fluorescent sensors of metal ions, reactive oxygen species, and thiols

    PubMed Central

    Hyman, Lynne M.; Franz, Katherine J.

    2013-01-01

    Oxidative stress is a common feature shared by many diseases, including neurodegenerative diseases. Factors that contribute to cellular oxidative stress include elevated levels of reactive oxygen species, diminished availability of detoxifying thiols, and the misregulation of metal ions (both redox-active iron and copper as well as non-redox active calcium and zinc). Deciphering how each of these components interacts to contribute to oxidative stress presents an interesting challenge. Fluorescent sensors can be powerful tools for detecting specific analytes within a complicated cellular environment. Reviewed here are several classes of small molecule fluorescent sensors designed to detect several molecular participants of oxidative stress. We focus our review on describing the design, function and application of probes to detect metal cations, reactive oxygen species, and intracellular thiol-containing compounds. In addition, we highlight the intricacies and complications that are often faced in sensor design and implementation. PMID:23440254

  18. Modulation of pressure-natriuresis by renal medullary reactive oxygen species and nitric oxide.

    PubMed

    O'Connor, Paul M; Cowley, Allen W

    2010-04-01

    The renal pressure-natriuresis mechanism is the dominant controller of body fluid balance and long-term arterial pressure. In recent years, it has become clear that the balance of reactive oxygen and nitrogen species within the renal medullary region is a key determinant of the set point of the renal pressure-natriuresis curve. The development of renal medullary oxidative stress causes dysfunction of the pressure-natriuresis mechanism and contributes to the development of hypertension in numerous disease models. The purpose of this review is to point out the known mechanisms within the renal medulla through which reactive oxygen and nitrogen species modulate the pressure-natriuresis response and to update the reader on recent advances in this field.

  19. Regulation of signal transduction by reactive oxygen species in the cardiovascular system

    PubMed Central

    Brown, David I.; Griendling, Kathy K.

    2015-01-01

    Oxidative stress has long been implicated in cardiovascular disease, but more recently, the role of reactive oxygen species in normal physiological signaling has been elucidated. Signaling pathways modulated by reactive oxygen species (ROS) are complex and compartmentalized, and we are only beginning to identify the molecular modifications of specific targets. Here we review the current literature regarding ROS signaling in the cardiovascular system, focusing on the role of ROS in normal physiology and how dysregulation of signaling circuits contributes to cardiovascular diseases including atherosclerosis, ischemia-reperfusion injury, cardiomyopathy and heart failure. In particular, we consider how ROS modulate signaling pathways related to phenotypic modulation, migration and adhesion, contractility, proliferation and hypertrophy, angiogenesis, endoplasmic reticulum stress, apoptosis and senescence. Understanding the specific targets of ROS may guide the development of the next generation of ROS-modifying therapies to reduce morbidity and mortality associated with oxidative stress. PMID:25634975

  20. Reactive oxygen species and antioxidant defense mechanisms in the oral cavity: a literature review.

    PubMed

    San Miguel, Symone M; Opperman, Lynne A; Allen, Edward P; Svoboda, Kathy K H

    2011-01-01

    Through dental procedures and environment, periodontal tissues are exposed to many types of reactive oxygen species (ROS). Recently, various forms of antioxidants have been introduced as an approach to fight dental diseases and improve general gingival health. This article focuses on the classification of antioxidants and the link between oxidative stress and periodontal disease. The protective mechanisms of antioxidants and how routine dental procedures may increase ROS is discussed. The final section reviews the effect of tobacco products on gingival health and disease.

  1. Depth zonation and bathymetric trends of deep-sea megafaunal scavengers of the Hawaiian Islands

    NASA Astrophysics Data System (ADS)

    Yeh, John; Drazen, Jeffrey C.

    2009-02-01

    The deep sea has been shown to exhibit strong depth zonation in species composition and abundance. Examination of these patterns can offer ecological insight into how organisms adapt and respond to changing environmental parameters that co-occur with depth. Here we provide the first tropical study on bathymetric zonation and other depth-related trends (size, abundance, and species richness) spanning shelf to abyssal depths of scavenging megafauna. Baited time-lapse free-vehicle cameras were used to examine the deep-sea benthic and demersal scavenging communities of the Hawaiian Islands, an area for which the biology and ecology have remained poorly studied below 2000 m. Twenty-two deployments ranging in depth from 250 to 4783 m yielded 37 taxa attracted to bait, including the first known occurrence of the family Zoarcidae in the Hawaiian Islands. Cluster analysis of Bray-Curtis similarity of species peak abundance ( nmax) revealed four main faunal zones (250-500, 1000, 1500-3000, and ⩾4000 m) with significant separation (ANOSIM, global R=0.907, p=0.001) between designated depth groups. A major faunal break was identified at the 500-1000 m transition where species turnover was greatest, coinciding with the location of the local oxygen minimum zone. Dominance in species assemblage shifted from decapod crustaceans to teleosts moving from shallow to deeper faunal zones. Significant size differences in total length with depth were found for two of the four fish species examined. A logarithmic decline was observed in scavenger relative abundance with depth. Evidence of interaction between scavenging species was also noted between Synaphobranchus affinis and Neolithodes sp. (competition) and Histiobranchus sp. and aristeid shrimp (predation), suggesting that interactions between scavengers could influence indices of abundance generated from baited camera data.

  2. Measurement of Reactive Oxygen Species, Reactive Nitrogen Species, and Redox-Dependent Signaling in the Cardiovascular System: A Scientific Statement From the American Heart Association.

    PubMed

    Griendling, Kathy K; Touyz, Rhian M; Zweier, Jay L; Dikalov, Sergey; Chilian, William; Chen, Yeong-Renn; Harrison, David G; Bhatnagar, Aruni

    2016-08-19

    Reactive oxygen species and reactive nitrogen species are biological molecules that play important roles in cardiovascular physiology and contribute to disease initiation, progression, and severity. Because of their ephemeral nature and rapid reactivity, these species are difficult to measure directly with high accuracy and precision. In this statement, we review current methods for measuring these species and the secondary products they generate and suggest approaches for measuring redox status, oxidative stress, and the production of individual reactive oxygen and nitrogen species. We discuss the strengths and limitations of different methods and the relative specificity and suitability of these methods for measuring the concentrations of reactive oxygen and reactive nitrogen species in cells, tissues, and biological fluids. We provide specific guidelines, through expert opinion, for choosing reliable and reproducible assays for different experimental and clinical situations. These guidelines are intended to help investigators and clinical researchers avoid experimental error and ensure high-quality measurements of these important biological species.

  3. In vitro propagation by asymbiotic seed germination and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity studies of tissue culture raised plants of three medicinally important species of dendrobium.

    PubMed

    Lo, Shu-Fung; Nalawade, Satish Manohar; Mulabagal, Vanisree; Matthew, Susan; Chen, Chung-Li; Kuo, Chao-Lin; Tsay, Hsin-Sheng

    2004-05-01

    A simple and efficient plant propagation system has been developed by asymbiotic germination of seeds in three medicinally important Dendrobium species, namely, Dendrobium tosaense, Dendrobium moniliforme, and Dendrobium linawianum. Plants obtained from natural habitats were grown in the greenhouse. The flowers were hand pollinated. Seeds of the capsules derived after 12 weeks of hand-pollination germinated asymbiotically (50-74%) on half strength Murashige and Skoog's (MS) basal medium with 3% sucrose and solidified with 0.9% Difco agar. Active growth in the germinated seedlings was achieved by re-culturing on full strength MS basal medium supplemented with 8% banana homogenate, 8% potato homogenate, 8% coconut water, 1.5% sucrose and 0.9% Difco agar. Healthy plantlets, transferred to plastic trays containing moss or moss and tree fern, successfully acclimatized (84-100%) in the greenhouse. A marked varied response was observed in the free radical scavenging activity of methanolic extracts of in vitro propagated plants, on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical using a UV spectrophotometer assay. Methanolic extracts were prepared by dissolving the powdered plant material, obtained from six months old in vitro propagated plants, each about 5 g, in boiling methanol. The percentage of scavenging effect of D. tosaense extract was 95.9% at 0.4 mg/ml concentration, whereas D. monoliforme, and D. linawianum extracts scavenged 83.4% and 92.3%, respectively, at a concentration of 0.4 mg/ml. All the extracts scavenged DPPH radical significantly in a concentration dependent manner.

  4. Inactivation effects of neutral reactive-oxygen species on Penicillium digitatum spores using non-equilibrium atmospheric-pressure oxygen radical source

    NASA Astrophysics Data System (ADS)

    Hashizume, Hiroshi; Ohta, Takayuki; Fengdong, Jia; Takeda, Keigo; Ishikawa, Kenji; Hori, Masaru; Ito, Masafumi

    2013-10-01

    The effectiveness of atomic and excited molecular oxygen species at inactivating Penicillium digitatum spores was quantitatively investigated by measuring these species and evaluating the spore inactivation rate. To avoid the effects of ultraviolet light and charged species, a non-equilibrium atmospheric-pressure radical source, which supplies only neutral radicals, was employed. Ground-state atomic oxygen (O(3Pj)) and excited molecular oxygen (O2(1Δg)) species were measured using vacuum ultraviolet absorption spectroscopy. The inactivation rate of spores was evaluated using the colony count method. The lifetimes of O(3Pj) and O2(1Δg) in an argon gas ambient at atmospheric pressure were found to be about 0.5 ms and much more than tens of ms, and their spore inactivation rates were about 10-17 cm3 s-1 and much lower than 10-21 cm3 s-1, respectively.

  5. [Ways of realizing apoptosis of human lymphocytes induced by UV-light and reactive oxygen species].

    PubMed

    Artiukhov, V G; Trubitsyna, M S; Nakvasina, M A; Solov'eva, E V; Lidokhova, O V

    2011-01-01

    Changes of DNA structural condition, the level of membrane Fas-receptor expression, caspase-3 functional activity, concentrations of Ca2+, p53 and cytochrome c proteins of human lymphocytes in dynamics of apoptosis development induced by UV-light (240-390 nm) at doses 151, 1510, 3020 J/m2 and reactive oxygen species (superoxide anion-radical, hydroxyl radicals, hydrogen peroxide, singlet oxygen) have been studied. UV-light and reactive oxygen species have been established to induce fragmentation of lymphocyte DNA after 20 h incubation of the modified cells. It has been shown, that the increase in the expression level of membrane death Fas-receptors is observed during 1-5 h after exposure oflymphocytes to UV-light and ROS compared with intact cells. Also revealed is augmentation of lymphocyte caspase-3 functional activity 4 h after generation of singlet oxygen, hydroxyl radical and hydrogen peroxide addition, as well as 8 and 24 and 6 and 8 h after UV-irradiation of the cells at doses 151 and 1510 J/m2, correspondingly. Using DNA-comet method made it possible to tape that DNA damages (single-strand breaks) appear 15-20 min after lymphocyte UV-irradiation at doses 1510 and 3020 J/m and addition of hydrogen peroxide in concentration 10(-6) mol/l (C1 type comet) and reach their maximum 6 h after modification of the cells (C2 and C3 type comets). It has been observed, that 6 h after exposure oflymphocytes to hydrogen peroxide and UV-light at doses 1510 and 3020 J/m2, the p53 level of investigated cells raises. It has also been shown that the higher level of calcium in lymphocyte cytosol in conditions of UV-light exposure (1510 J/m2) and exogenous generation of reactive oxygen species is caused by Ca2+ exit from intracellular depots as a result of activating the components of the phosphoinositide mechanism for transferring information into a cell. Ideas about correlation between alterations of the calcium level and initiation of programmed cellular destruction of human

  6. The evaluation of potential limonene scavengers

    SciTech Connect

    Roth, R.; Ebert, D.; Shepodd, T.J.

    1995-01-01

    This work is the study of different scavengers of limonene. Limonene is a citrus-based, low toxicity, hydrocarbon solvent for cleaning circuit boards and other parts. Though almost all limonene evaporates after cleaning procedures, trace residual limonene would be a concern if allowed to migrate freely through a sealed system. This work was charted to investigate materials that would effectively scavenge and permanently immobilize trace limonene. The requirements of a successful scavenger are the following: it must remove >90% of 30 mg/l limonene from a sealed volume with 3 months, at 20--25 C; it must not release any volatiles over prolonged aging; it must be packaged such that limonene vapors can access the scavenger, but not such that the scavenging medium can migrate; and it must operate in the presence of water, oxygen, pentane, toluene, and carbon dioxide gases. A number of adsorbents were evaluated. Additionally, a scheme for scavenging limonene by chemical reaction was investigated at Sandia. This attempt was not successful. The details of this investigation are found at the end of this report.

  7. Wolbachia Do Not Induce Reactive Oxygen Species-Dependent Immune Pathway Activation in Aedes albopictus

    PubMed Central

    Molloy, Jennifer C.; Sinkins, Steven P.

    2015-01-01

    Aedes albopictus is a major vector of dengue (DENV) and chikungunya (CHIKV) viruses, causing millions of infections annually. It naturally carries, at high frequency, the intracellular inherited bacterial endosymbiont Wolbachia strains wAlbA and wAlbB; transinfection with the higher-density Wolbachia strain wMel from Drosophila melanogaster led to transmission blocking of both arboviruses. The hypothesis that reactive oxygen species (ROS)-induced immune activation plays a role in arbovirus inhibition in this species was examined. In contrast to previous observations in Ae. aegypti, elevation of ROS levels was not observed in either cell lines or mosquito lines carrying the wild-type Wolbachia or higher-density Drosophila Wolbachia strains. There was also no upregulation of genes controlling innate immune pathways or with antioxidant/ROS-producing functions. These data suggest that ROS-mediated immune activation is not an important component of the viral transmission-blocking phenotype in this species. PMID:26287231

  8. UV-B-Induced PR-1 Accumulation Is Mediated by Active Oxygen Species.

    PubMed

    Green, R.; Fluhr, R.

    1995-02-01

    Depletion of the stratospheric ozone layer may result in an increase in the levels of potentially harmful UV-B radiation reaching the surface of the earth. We have found that UV-B is a potent inducer of the plant pathogenesis-related protein PR-1 in tobacco leaves. UV-B fluences required for PR-1 accumulation are similar to those of other UV-B-induced responses. The UV-B-induced PR-1 accumulation was confined precisely to the irradiated area of the leaf but displayed no leaf tissue specificity. A study of some of the possible components of the signal transduction pathway between UV-B and PR-1 induction showed that photosynthetic processes are not essential, and photoreversible DNA damage is not involved. Antioxidants and cycloheximide were able to block the induction of PR-1 by UV-B, and treatment of leaves with a generator of reactive oxygen resulted in the accumulation of PR-1 protein. These results demonstrate an absolute requirement for active oxygen species and protein synthesis in this UV-B signal transduction pathway. In contrast, we also show that other elicitors, notably salicylic acid, are able to elicit PR-1 via nonreactive oxygen species-requiring pathways.

  9. Fluorescence-based assay for reactive oxygen species: A protective role for creatinine

    SciTech Connect

    Glazer, A.N. )

    1988-06-01

    Attack by reactive oxygen species leads to a decay in phycoerythrin fluorescence emission. This phenomenon provides a versatile new assay for small molecules and macromolecules that can function as protective compounds. With 1-2 {times} 10{sup {minus}8} M phycoerythrin, under conditions where peroxyl radical generation is rate-limiting, the fluorescence decay follows apparent zero-order kinetics. On reaction with HO{center dot}, generated with the ascorbate-Cu{sup 2+} system, the fluorescence decays with apparent first-order kinetics. Examination of the major components of human urine in this assay confirms that at physiological concentrations, urate protects against both types of oxygen radicals. A novel finding is that creatinine protects efficiently by a chelation mechanism against radical damage in the ascorbate-Cu{sup 2+} system at creatinine, ascorbate, and Cu{sup 2+} concentrations comparable to those in normal urine. Urate and creatinine provide complementary modes of protection against reactive oxygen species in the urinary tract.

  10. Cytotoxicity of InP/ZnS quantum dots related to reactive oxygen species generation.

    SciTech Connect

    Chibli, H.; Carlini, L.; Park, S.; Dimitrijevic, N. M.; Nadeau, J. L.

    2011-01-01

    Indium phosphide (InP) quantum dots (QDs) have emerged as a presumably less hazardous alternative to cadmium-based particles, but their cytotoxicity has not been well examined. Although their constituent elements are of very low toxicity to cells in culture, they nonetheless exhibit phototoxicity related to generation of reactive oxygen species by excited electrons and/or holes interacting with water and molecular oxygen. Using spin-trap electron paramagnetic resonance (EPR) spectroscopy and reporter assays, we find a considerable amount of superoxide and a small amount of hydroxyl radical formed under visible illumination of biocompatible InP QDs with a single ZnS shell, comparable to what is seen with CdTe. A double thickness shell reduces the reactive oxygen species concentration approximately two-fold. Survival assays in five cell lines correspondingly indicate a distinct reduction in toxicity with the double-shell InP QDs. Toxicity varies significantly across cell lines according to the efficiency of uptake, being overall significantly less than what is seen with CdTe or CdSe/ZnS. This indicates that InP QDs are a useful alternative to cadmium-containing QDs, while remaining capable of electron-transfer processes that may be undesirable or which may be exploited for photosensitization applications.

  11. Antimicrobial strategies centered around reactive oxygen species - bactericidal antibiotics, photodynamic therapy and beyond

    PubMed Central

    Vatansever, Fatma; de Melo, Wanessa C.M.A.; Avci, Pinar; Vecchio, Daniela; Sadasivam, Magesh; Gupta, Asheesh; Chandran, Rakkiyappan; Karimi, Mahdi; Parizotto, Nivaldo A; Yin, Rui; Tegos, George P; Hamblin, Michael R

    2013-01-01

    Reactive oxygen species (ROS) can attack a diverse range of targets to exert antimicrobial activity, which accounts for their versatility in mediating host defense against a broad range of pathogens. Most ROS are formed by the partial reduction of molecular oxygen. Four major ROS are recognized comprising: superoxide (O2•−), hydrogen peroxide (H2O2), hydroxyl radical (•OH), and singlet oxygen (1O2), but they display very different kinetics and levels of activity. The effects of O2•− and H2O2 are less acute than those of •OH and 1O2, since the former are much less reactive and can be detoxified by endogenous antioxidants (both enzymatic and non-enzymatic) that are induced by oxidative stress. In contrast, no enzyme can detoxify •OH or 1O2, making them extremely toxic and acutely lethal. The present review will highlight the various methods of ROS formation and their mechanism of action. Antioxidant defenses against ROS in microbial cells and the use of ROS by antimicrobial host defense systems are covered. Antimicrobial approaches primarily utilizing ROS comprise both bactericidal antibiotics, and non-pharmacological methods such as photodynamic therapy, titanium dioxide photocatalysis, cold plasma and medicinal honey. A brief final section covers, reactive nitrogen species, and related therapeutics, such as acidified nitrite and nitric oxide releasing nanoparticles. PMID:23802986

  12. Photochemistry of Dissolved Black Carbon Released from Biochar: Reactive Oxygen Species Generation and Phototransformation.

    PubMed

    Fu, Heyun; Liu, Huiting; Mao, Jingdong; Chu, Wenying; Li, Qilin; Alvarez, Pedro J J; Qu, Xiaolei; Zhu, Dongqiang

    2016-02-02

    Dissolved black carbon (BC) released from biochar can be one of the more photoactive components in the dissolved organic matter (DOM) pool. Dissolved BC was mainly composed of aliphatics and aromatics substituted by aromatic C-O and carboxyl/ester/quinone moieties as determined by solid-state nuclear magnetic resonance. It underwent 56% loss of absorbance at 254 nm, almost complete loss of fluorescence, and 30% mineralization during a 169 h simulated sunlight exposure. Photoreactions preferentially targeted aromatic and methyl moieties, generating CH2/CH/C and carboxyl/ester/quinone functional groups. During irradiation, dissolved BC generated reactive oxygen species (ROS) including singlet oxygen and superoxide. The apparent quantum yield of singlet oxygen was 4.07 ± 0.19%, 2-3 fold higher than many well-studied DOM. Carbonyl-containing structures other than aromatic ketones were involved in the singlet oxygen sensitization. The generation of superoxide apparently depended on electron transfer reactions mediated by silica minerals in dissolved BC, in which phenolic structures served as electron donors. Self-generated ROS played an important role in the phototransformation. Photobleaching of dissolved BC decreased its ability to further generate ROS due to lower light absorption. These findings have significant implications on the environmental fate of dissolved BC and that of priority pollutants.

  13. Sexual Preferences in Nutrient Utilization Regulate Oxygen Consumption and Reactive Oxygen Species Generation in Schistosoma mansoni: Potential Implications for Parasite Redox Biology

    PubMed Central

    Oliveira, Matheus P.; Correa Soares, Juliana B. R.; Oliveira, Marcus F.

    2016-01-01

    Schistosoma mansoni, one of the causative agents of human schistosomiasis, has a unique antioxidant network that is key to parasite survival and a valuable chemotherapeutic target. The ability to detoxify and tolerate reactive oxygen species increases along S. mansoni development in the vertebrate host, suggesting that adult parasites are more exposed to redox challenges than young stages. Indeed, adult parasites are exposed to multiple redox insults generated from blood digestion, activated immune cells, and, potentially, from their own parasitic aerobic metabolism. However, it remains unknown how reactive oxygen species are produced by S. mansoni metabolism, as well as their biological effects on adult worms. Here, we assessed the contribution of nutrients and parasite gender to oxygen utilization pathways, and reactive oxygen species generation in whole unpaired adult S. mansoni worms. We also determined the susceptibilities of both parasite sexes to a pro-oxidant challenge. We observed that glutamine and serum importantly contribute to both respiratory and non-respiratory oxygen utilization in adult worms, but with different proportions among parasite sexes. Analyses of oxygen utilization pathways revealed that respirato