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Sample records for reactive quinones generation

  1. Switching Futile para-Quinone to Efficient Reactive Oxygen Species Generator: Ubiquitin-Specific Protease-2 Inhibition, Electrocatalysis, and Quantification.

    PubMed

    Gopinath, Pushparathinam; Mahammed, Atif; Eilon-Shaffer, Tal; Nawatha, Mickal; Ohayon, Shimrit; Shabat, Doron; Gross, Zeev; Brik, Ashraf

    2017-09-05

    Understanding the correlation between structural features of small-molecule drugs and their mode of action is a fascinating topic and crucial for the drug-discovery process. However, in many cases, knowledge of the exact parameters that dictate the mode of action is still lacking. Following a large screening for ubiquitin specific protease 2 (USP2) inhibition, an effective para-quinone-based inhibitor with an unclear mode of action was identified. To gain a deeper understanding of the mechanism of inhibition, a set of para-quinones were prepared and studied for USP2 inhibition, electrocatalysis, and reactive oxygen species (ROS) quantification. The excellent correlation obtained from the above-mentioned studies disclosed a distinct pattern of "N-C=O-N" in the bicyclic para-quinones to be a crucial factor for ROS generation, and demonstrated that minor changes in such a skeleton drastically altered the ROS-generating ability. The knowledge acquired herein would serve as an important guideline for future medicinal chemistry optimization of related structures to select the preferred mode of action. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. In cellulo monitoring of quinone reductase activity and reactive oxygen species production during the redox cycling of 1,2 and 1,4 quinones.

    PubMed

    Cassagnes, Laure-Estelle; Perio, Pierre; Ferry, Gilles; Moulharat, Natacha; Antoine, Mathias; Gayon, Régis; Boutin, Jean A; Nepveu, Françoise; Reybier, Karine

    2015-12-01

    Quinones are highly reactive molecules that readily undergo either one- or two-electron reduction. One-electron reduction of quinones or their derivatives by enzymes such as cytochrome P450 reductase or other flavoproteins generates unstable semiquinones, which undergo redox cycling in the presence of molecular oxygen leading to the formation of highly reactive oxygen species. Quinone reductases 1 and 2 (QR1 and QR2) catalyze the two-electron reduction of quinones to form hydroquinones, which can be removed from the cell by conjugation of the hydroxyl with glucuronide or sulfate thus avoiding its autoxidation and the formation of free radicals and highly reactive oxygen species. This characteristic confers a detoxifying enzyme role to QR1 and QR2, even if this character is strongly linked to the excretion capacity of the cell. Using EPR spectroscopy and confocal microscopy we demonstrated that the amount of reactive oxygen species (ROS) produced by Chinese hamster ovary (CHO) cells overexpressing QR1 or QR2 compared to naive CHO cells was determined by the quinone structural type. Indeed, whereas the amount of ROS produced in the cell was strongly decreased with para-quinones such as menadione in the presence of quinone reductase 1 or 2, a strong increase in ROS was recorded with ortho-quinones such as adrenochrome, aminochrome, dopachrome, or 3,5-di-tert-butyl-o-benzoquinone in cells overexpressing QR, especially QR2. These differences could originate from the excretion process, which is different for para- and ortho-quinones. These results are of particular interest in the case of dopamine considering the association of QR2 with various neurological disorders such as Parkinson disease. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Reactivities of Quinone Methides versus o-Quinones in Catecholamine Metabolism and Eumelanin Biosynthesis

    PubMed Central

    Sugumaran, Manickam

    2016-01-01

    Melanin is an important biopolymeric pigment produced in a vast majority of organisms. Tyrosine and its hydroxylated product, dopa, form the starting material for melanin biosynthesis. Earlier studies by Raper and Mason resulted in the identification of dopachrome and dihydroxyindoles as important intermediates and paved way for the establishment of well-known Raper–Mason pathway for the biogenesis of brown to black eumelanins. Tyrosinase catalyzes the oxidation of tyrosine as well as dopa to dopaquinone. Dopaquinone thus formed, undergoes intramolecular cyclization to form leucochrome, which is further oxidized to dopachrome. Dopachrome is either converted into 5,6-dihydroxyindole by decarboxylative aromatization or isomerized into 5,6-dihydroxyindole-2-carboxylic acid. Oxidative polymerization of these two dihydroxyindoles eventually produces eumelanin pigments via melanochrome. While the role of quinones in the biosynthetic pathway is very well acknowledged, that of isomeric quinone methides, however, remained marginalized. This review article summarizes the key role of quinone methides during the oxidative transformation of a vast array of catecholamine derivatives and brings out the importance of these transient reactive species during the melanogenic process. In addition, possible reactions of quinone methides at various stages of melanogenesis are discussed. PMID:27657049

  4. Reactivities of Quinone Methides versus o-Quinones in Catecholamine Metabolism and Eumelanin Biosynthesis.

    PubMed

    Sugumaran, Manickam

    2016-09-20

    Melanin is an important biopolymeric pigment produced in a vast majority of organisms. Tyrosine and its hydroxylated product, dopa, form the starting material for melanin biosynthesis. Earlier studies by Raper and Mason resulted in the identification of dopachrome and dihydroxyindoles as important intermediates and paved way for the establishment of well-known Raper-Mason pathway for the biogenesis of brown to black eumelanins. Tyrosinase catalyzes the oxidation of tyrosine as well as dopa to dopaquinone. Dopaquinone thus formed, undergoes intramolecular cyclization to form leucochrome, which is further oxidized to dopachrome. Dopachrome is either converted into 5,6-dihydroxyindole by decarboxylative aromatization or isomerized into 5,6-dihydroxyindole-2-carboxylic acid. Oxidative polymerization of these two dihydroxyindoles eventually produces eumelanin pigments via melanochrome. While the role of quinones in the biosynthetic pathway is very well acknowledged, that of isomeric quinone methides, however, remained marginalized. This review article summarizes the key role of quinone methides during the oxidative transformation of a vast array of catecholamine derivatives and brings out the importance of these transient reactive species during the melanogenic process. In addition, possible reactions of quinone methides at various stages of melanogenesis are discussed.

  5. Interactive enhancements of ascorbic acid and iron in hydroxyl radical generation in quinone redox cycling.

    PubMed

    Li, Yi; Zhu, Tong; Zhao, Jincai; Xu, Bingye

    2012-09-18

    Quinones are toxicological substances in inhalable particulate matter (PM). The mechanisms by which quinones cause hazardous effects can be complex. Quinones are highly active redox molecules that can go through a redox cycle with their semiquinone radicals, leading to formation of reactive oxygen species. Electron spin resonance spectra have been reported for semiquinone radicals in PM, indicating the importance of ascorbic acid and iron in quinone redox cycling. However, these findings are insufficient for understanding the toxicity associated with quinone exposure. Herein, we investigated the interactions among anthraquinone (AQ), ascorbic acid, and iron in hydroxyl radical (·OH) generation through the AQ redox cycling process in a physiological buffer. We measured ·OH concentration and analyzed the free radical process. Our results showed that AQ, ascorbic acid, and iron have synergistic effects on ·OH generation in quinone redox cycling; i.e., ascorbyl radical oxidized AQ to semiquinone radical and started the redox cycling, iron accelerated this oxidation and enhanced ·OH generation through Fenton reactions, while ascorbic acid and AQ could help iron to release from quartz surface and enhance its bioavailability. Our findings provide direct evidence for the redox cycling hypothesis about airborne particle surface quinone in lung fluid.

  6. Quinones as photosensitizer for photodynamic therapy: ROS generation, mechanism and detection methods.

    PubMed

    Rajendran, M

    2016-03-01

    Photodynamic therapy (PDT) is based on the dye-sensitized photooxidation of biological matter in the target tissue, and utilizes light activated drugs for the treatment of a wide variety of malignancies. Quinones and porphyrins moiety are available naturally and involved in the biological process. Quinone metabolites perform a variety of key functions in plants which includes pathogen protection, oxidative phosphorylation, and redox signaling. Quinones and porphyrin are biologically accessible and will not create any allergic effects. In the field of photodynamic therapy, porphyrin derivatives are widely used, because it absorb in the photodynamic therapy window region (600-900 nm). Hence, researchers synthesize drugs based on porphyrin structure. Benzoquinone and its simple polycyclic derivatives such as naphthaquinone and anthraquinones absorb at lower wavelength region (300-400 nm), which is lower than porphyrin. Hence they are not involved in PDT studies. However, higher polycyclic quinones absorb in the photodynamic therapy window region (600-900 nm), because of its conjugation and can be used as PDT agents. Redox cycling has been proposed as a possible mechanism of action for many quinone species. Quinones are involved in the photodynamic as well as enzymatic generation of reactive oxygen species (ROS). Generations of ROS may be measured by optical, phosphorescence and EPR methods. The photodynamically generated ROS are also involved in many biological events. The photo-induced DNA cleavage by quinones correlates with the ROS generating efficiencies of the quinones. In this review basic reactions involving photodynamic generation of ROS by quinones and their biological applications were discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Quinone

    Integrated Risk Information System (IRIS)

    Quinone ; CASRN 106 - 51 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effects )

  8. Molecular characterization of dopamine-derived quinones reactivity toward NADH and glutathione: implications for mitochondrial dysfunction in Parkinson disease.

    PubMed

    Bisaglia, Marco; Soriano, Maria Eugenia; Arduini, Irene; Mammi, Stefano; Bubacco, Luigi

    2010-09-01

    Oxidative stress and mitochondrial dysfunction, especially at the level of complex I of the electronic transport chain, have been proposed to be involved in the pathogenesis of Parkinson disease (PD). A plausible source of oxidative stress in nigral dopaminergic neurons is the redox reactions that specifically involve dopamine (DA) and produce various toxic molecules, i.e., free radicals and quinone species (DAQ). It has been shown that DA oxidation products can induce various forms of mitochondrial dysfunction, such as mitochondrial swelling and decreased electron transport chain activity. In the present work, we analyzed the potentially toxic effects of DAQ on mitochondria and, specifically, on the NADH and GSH pools. Our results demonstrate that the generation of DAQ in isolated respiring mitochondria triggers the opening of the permeability transition pore most probably by inducing oxidation of NADH, while GSH levels are not affected. We then characterized in vitro, by UV and NMR spectroscopy, the reactivity of different DA-derived quinones, i.e., dopamine-o-quinone (DQ), aminochrome (AC) and indole-quinone (IQ), toward NADH and GSH. Our results indicate a very diverse reactivity for the different DAQ studied that may contribute to unravel the complex molecular mechanisms underlying oxidative stress and mitochondria dysfunction in the context of PD.

  9. A Structural Determinant of Chemical Reactivity and Potential Health Effects of Quinones from Natural Products

    PubMed Central

    Tu, Tingting; Giblin, Daryl; Gross, Michael L.

    2011-01-01

    Although many phenols and catechols found as polyphenol natural products are antioxidants and have putative disease-preventive properties, others have deleterious health effects. One possible route to toxicity is the bioactivation of the phenolic function to quinones that are electrophilic, redox-agents capable of modifying DNA and proteins. The structure-property relationships of biologically important quinones and their precursors may help understand the balance between their health benefits and risks. We describe a mass-spectrometry-based study of four quinones produced by oxidizing flavanones and flavones. Those with a C2-C3 double bond on ring C of the flavonoid stabilize by delocalization an incipient positive charge from protonation and render the protonated quinone particularly susceptible to nucleophilic attack. We hypothesize that the absence of this double bond is one specific structural determinant that is responsible for the ability of quinones to modify biological macromolecules. Those quinones containing a C2-C3 single bond have relative higher aqueous stability and longer half-lives than those with a double bond at the same position; the latter have short half-lives at or below ~ 1 s. Quinones with a C2-C3 double bond show little ability to depurinate DNA because they are rapidly hydrated to unreactive species. Molecular-orbital calculations support that quinone hydration by a highly structure-dependent mechanism accounts for their chemical properties. The evidence taken together support a hypothesis that those flavonoids and related natural products that undergo oxidation to quinones and are then rapidly hydrated are unlikely to damage important biological macromolecules. PMID:21721570

  10. Quinone-reactive proteins devoid of haem b form widespread membrane-bound electron transport modules in bacterial respiration.

    PubMed

    Simon, Jörg; Kern, Melanie

    2008-10-01

    Many quinone-reactive enzyme complexes that are part of membrane-integral eukaryotic or prokaryotic respiratory electron transport chains contain one or more haem b molecules embedded in the membrane. In recent years, various novel proteins have emerged that are devoid of haem b but are thought to fulfil a similar function in bacterial anaerobic respiratory systems. These proteins are encoded by genes organized in various genomic arrangements and are thought to form widespread membrane-bound quinone-reactive electron transport modules that exchange electrons with redox partner proteins located at the outer side of the cytoplasmic membrane. Prototypic representatives are the multihaem c-type cytochromes NapC, NrfH and TorC (NapC/NrfH family), the putative iron-sulfur protein NapH and representatives of the NrfD/PsrC family. Members of these protein families vary in the number of their predicted transmembrane segments and, consequently, diverse quinone-binding sites are expected. Only a few of these enzymes have been isolated and characterized biochemically and high-resolution structures are limited. This mini-review briefly summarizes predicted and experimentally demonstrated properties of the proteins in question and discusses their role in electron transport and bioenergetics of anaerobic respiration.

  11. DNA strand scission by polycyclic aromatic hydrocarbon o-quinones: role of reactive oxygen species, Cu(II)/Cu(I) redox cycling, and o-semiquinone anion radicals,.

    PubMed

    Flowers, L; Ohnishi, S T; Penning, T M

    1997-07-15

    In previous studies, benzo[a]pyrene-7,8-dione (BPQ), a polycyclic aromatic hydrocarbon (PAH) o-quinone, was found to be 200-fold more potent as a nuclease than (+/-)-anti-7,8-dihydroxy-9,10-epoxy-7,8,9, 10-tetrahydrobenzo[a]pyrene, a suspect human carcinogen. The mechanism of strand scission mediated by naphthalene-1,2-dione (NPQ) and BPQ was further characterized using either phiX174 DNA or poly(dG).poly(dC) as the target DNA. Strand scission was extensive, dependent on the concentration of o-quinone (0-10 microM), and required the presence of NADPH (1 mM) and CuCl2 (10 microM). The production of reactive species, i.e., superoxide anion radical, o-semiquinone anion (SQ) radical, hydrogen peroxide (H2O2), hydroxyl radical (OH.), and Cu(I), was measured in the incubation mixtures. The formation of SQ radicals was measured by EPR spectroscopy under anaerobic conditions in the presence of NADPH. A Cu(II)/Cu(I) redox cycle was found to be critical for DNA cleavage. No strand scission occurred in the absence of Cu(II) or when Cu(I) was substituted, yet Cu(I) was required for OH* production. Both DNA strand scisson and OH. formation were decreased to an equal extent, albeit not completely, by the inclusion of OH. scavengers (mannitol, soduim benzoate, and formic acid) or Cu(I) chelators (bathocuproine and neocuproine). In contrast, although the SQ radical signals of NPQ and BPQ were quenched by DNA, no strand scission was observed. When calf thymus DNA was treated with PAH o-quinones, malondialdehyde (MDA) was released by acid hydrolysis. The formation of MDA was inhibited by OH. scavengers suggesting that OH* cleaved the 2'-deoxyribose moiety in the DNA to produce base propenals. These studies indicate that for PAH o-quinones to act as nucleases, NADPH, Cu(II), Cu(I), H2O2, and OH*, were necessary and that the primary species responsible for DNA fragmentation was OH., generated by a Cu(I)-catalyzed Fenton reaction. The genotoxicity of PAH o-quinones may play a role in

  12. Role of the NAD(P)H quinone oxidoreductase NQR and the cytochrome b AIR12 in controlling superoxide generation at the plasma membrane.

    PubMed

    Biniek, Catherine; Heyno, Eiri; Kruk, Jerzy; Sparla, Francesca; Trost, Paolo; Krieger-Liszkay, Anja

    2017-04-01

    The quinone reductase NQR and the b-type cytochrome AIR12 of the plasma membrane are important for the control of reactive oxygen species in the apoplast. AIR12 and NQR are two proteins attached to the plant plasma membrane which may be important for generating and controlling levels of reactive oxygen species in the apoplast. AIR12 (Auxin Induced in Root culture) is a single gene of Arabidopsis that codes for a mono-heme cytochrome b. The NADPH quinone oxidoreductase NQR is a two-electron-transferring flavoenzyme that contributes to the generation of O 2(•-) in isolated plasma membranes. A. thaliana double knockout plants of both NQR and AIR12 generated more O 2(•-) and germinated faster than the single mutant affected in AIR12. To test whether NQR and AIR12 are able to interact functionally, recombinant purified proteins were added to plasma membranes isolated from soybean hypocotyls. In vitro NADH-dependent O 2(•-) production at the plasma membrane in the presence of NQR was reduced upon addition of AIR12. Electron donation from semi-reduced menadione to AIR12 was shown to take place. Biochemical analysis showed that purified plasma membrane from soybean hypocotyls or roots contained phylloquinone and menaquinone-4 as redox carriers. This is the first report on the occurrence of menaquinone-4 in eukaryotic photosynthetic organisms. We propose that NQR and AIR12 interact via the quinone, allowing an electron transfer from cytosolic NAD(P)H to apoplastic monodehydroascorbate and control thereby the level of reactive oxygen production and the redox state of the apoplast.

  13. Lactococcus lactis catalyses electricity generation at microbial fuel cell anodes via excretion of a soluble quinone.

    PubMed

    Freguia, Stefano; Masuda, Masaki; Tsujimura, Seiya; Kano, Kenji

    2009-09-01

    Lactococcus lactis is a gram-positive, normally homolactic fermenter that is known to produce several kinds of membrane associated quinones, which are able to mediate electron transfer to extracellular electron acceptors such as Fe(3+), Cu(2+) and hexacyanoferrate. Here we show that this bacterium is also capable of performing extracellular electron transfer to anodes by utilizing at least two soluble redox mediators, as suggested by the two-step catalytic current developed. One of these two mediators was herein suggested to be 2-amino-3-dicarboxy-1,4-naphthoquinone (ACNQ), via evaluation of standard redox potential, ability of the bacterium to exploit the quinone when exogenously provided, as well as by high performance liquid chromatography coupled with UV spectrum analysis. During electricity generation, L. lactis slightly deviated from its normal homolactic metabolism by excreting acetate and pyruvate in stoichiometric amounts with respect to the electrical current. In this metabolism, the anode takes on the role of electron sink for acetogenic fermentation. The finding that L. lactis self-catalyses anodic electron transfer by excretion of redox mediators is remarkable as the mechanisms of extracellular electron transfer by pure cultures of gram-positive bacteria had previously never been elucidated.

  14. Antineoplastic Isoflavonoids Derived from Intermediate ortho-Quinone Methides Generated from Mannich Bases.

    PubMed

    Frasinyuk, Mykhaylo S; Mrug, Galyna P; Bondarenko, Svitlana P; Khilya, Volodymyr P; Sviripa, Vitaliy M; Syrotchuk, Oleksandr A; Zhang, Wen; Cai, Xianfeng; Fiandalo, Michael V; Mohler, James L; Liu, Chunming; Watt, David S

    2016-03-17

    The regioselective condensations of various 7-hydroxyisoflavonoids with bis(N,N-dimethylamino)methane in a Mannich reaction provided C-8 N,N-dimethylaminomethyl-substituted isoflavonoids in good yield. Similar condensations of 7-hydroxy-8-methylisoflavonoids led to the C-6-substituted analogs. Thermal eliminations of dimethylamine from these C-6 or C-8 N,N-dimethylaminomethyl-substituted isoflavonoids generated ortho-quinone methide intermediates within isoflavonoid frameworks for the first time. Despite other potential competing outcomes, these ortho-quinone methide intermediates trapped dienophiles including 2,3-dihydrofuran, 3,4-dihydro-2H-pyran, 3-(N,N-dimethylamino)-5,5-dimethyl-2-cyclohexen-1-one, 1-morpholinocyclopentene, and 1-morpholinocyclohexene to give various inverse electron-demand Diels-Alder adducts. Several adducts derived from 8-N,N-dimethylaminomethyl-substituted isoflavonoids displayed good activity in the 1-10 μm concentration range in an in vitro proliferation assay using the PC-3 prostate cancer cell line.

  15. Electron transfer capacity dependence of quinone-mediated Fe(III) reduction and current generation by Klebsiella pneumoniae L17.

    PubMed

    Li, Xiaomin; Liu, Liang; Liu, Tongxu; Yuan, Tian; Zhang, Wei; Li, Fangbai; Zhou, Shungui; Li, Yongtao

    2013-06-01

    Quinone groups in exogenous electron shuttles can accelerate extracellular electron transfer (EET) from bacteria to insoluble terminal electron acceptors, such as Fe(III) oxides and electrodes, which are important in biogeochemical redox processes and microbial electricity generation. However, the relationship between quinone-mediated EET performance and electron-shuttling properties of the quinones remains incompletely characterized. This study investigates the effects of a series of synthetic quinones (SQs) on goethite reduction and current generation by a fermenting bacterium Klebsiella pneumoniae L17. In addition, the voltammetric behavior and electron transfer capacities (ETCs) of SQ, including electron accepting (EAC) and donating (EDC) capacities, is also examined using electrochemical methods. The results showed that SQ can significantly increase both the Fe(III) reduction rates and current outputs of L17. Each tested SQ reversibly accepted and donated electrons as indicated by the cyclic voltammograms. The EAC and EDC results showed that Carmine and Alizarin had low relative capacities of electron transfer, whereas 9,10-anthraquinone-2,6-disulfonic acid (AQDS), 2-hydroxy-1,4-naphthoquinone (2-HNQ), and 5-hydroxy-1,4-naphthoquinone (5-HNQ) showed stronger relative ETC, and 9,10-anthraquinone-2-carboxylic acid (AQC) and 9,10-anthraquinone-2-sulfonic acid (AQS) had high relative ETC. Enhancement of microbial goethite reduction kinetics and current outputs by SQ had a good linear relationship with their ETC, indicating that the effectiveness of quinone-mediated EET may be strongly dependent on the ETC of the quinones. Therefore, the presence of quinone compounds and fermenting microorganisms may increase the diversity of microbial populations that contribute to element transformation in natural environments. Moreover, ETC determination of different SQ would help to evaluate their performance for microbial EET under anoxic conditions. Copyright © 2013 Elsevier

  16. Bioactivation of Nevirapine to a Reactive Quinone Methide: Implications for Liver Injury

    PubMed Central

    2012-01-01

    Nevirapine (NVP) treatment is associated with a significant incidence of liver injury. We developed an anti-NVP antiserum to determine the presence and pattern of covalent binding of NVP to mouse, rat, and human hepatic tissues. Covalent binding to hepatic microsomes from male C57BL/6 mice and male Brown Norway rats was detected on Western blots; the major protein had a mass of ∼55 kDa. Incubation of NVP with rat CYP3A1 and 2C11 or human CYP3A4 also led to covalent binding. Treatment of female Brown Norway rats or C57BL/6 mice with NVP led to extensive covalent binding to a wide range of proteins. Co-treatment with 1-aminobenzotriazole dramatically changed the pattern of binding. The covalent binding of 12-hydroxy-NVP, the pathway that leads to a skin rash, was much less than that of NVP, both in vitro and in vivo. An analogue of NVP in which the methyl hydrogens were replaced by deuterium also produced less covalent binding than NVP. These data provide strong evidence that covalent binding of NVP in the liver is due to a quinone methide formed by oxidation of the methyl group. Attempts were made to develop an animal model of NVP-induced liver injury in mice. There was a small increase in ALT in some NVP-treated male C57BL/6 mice at 3 weeks that resolved despite continued treatment. Male Cbl-b–/– mice dosed with NVP had an increase in ALT of >200 U/L, which also resolved despite continued treatment. Liver histology in these animals showed focal areas of complete necrosis, while most of the liver appeared normal. This is a different pattern from the histology of NVP-induced liver injury in humans. This is the first study to report hepatic covalent binding of NVP and also liver injury in mice. It is likely that the quinone methide metabolite is responsible for NVP-induced liver injury. PMID:22793666

  17. The quinone-reactive Ni/Fe-hydrogenase of Wolinella succinogenes.

    PubMed

    Dross, F; Geisler, V; Lenger, R; Theis, F; Krafft, T; Fahrenholz, F; Kojro, E; Duchêne, A; Tripier, D; Juvenal, K

    1992-05-15

    The hydrogenase (Hyd) isolated from the cytoplasmic membrane of Wolinella succinogenes consists of three polypeptides (HydA, HydB and HydC) and contains cytochrome b (6.4 mumol/g protein), which was reduced upon the addition of H2. The enzyme catalyzed the reduction of 2,3-dimethyl-1,4-naphthoquinone with H2, in contrast to an earlier preparation which was made up of HydA and HydB only and did not contain cytochrome b (Unden, G., Böcher, R., Knecht, J. & Kröger, A. (1982) FEBS Lett. 145, 230-234). This suggests that HydC is a cytochrome b which serves as a mediator in the electron transfer from H2 to the quinone. The hydrogenase genes were cloned, sequenced and identified by sequence comparison with the N-termini of the three subunits. The three genes were arranged in the order hydA, hydB, hydC, with the transcription start site in front of hydA, and were present only once on the genome. Separated by an intergene region of 69 nucleotides, hydC was followed by at least two more open reading frames of unknown function. The amino acid sequences derived from hydA, hydB and hydC were similar to those of the membrane Ni-hydrogenases of seven other bacteria. HydA and HydB also showed similarity to the small and the large subunits of periplasmic Ni-hydrogenases. HydC was predicted to contain four hydrophobic segments which might span the bacterial membrane. Two histidine residues located in hydrophobic segments are conserved in the corresponding sequences of the other membrane hydrogenases and might ligate the haem B.

  18. NADPH:Quinone Oxidoreductase 1 Regulates Host Susceptibility to Ozone via Isoprostane Generation*

    PubMed Central

    Kummarapurugu, Apparao B.; Fischer, Bernard M.; Zheng, Shuo; Milne, Ginger L.; Ghio, Andrew J.; Potts-Kant, Erin N.; Foster, W. Michael; Soderblom, Erik J.; Dubois, Laura G.; Moseley, M. Arthur; Thompson, J. Will; Voynow, Judith A.

    2013-01-01

    NADPH:quinone oxidoreductase 1 (NQO1) is recognized as a major susceptibility gene for ozone-induced pulmonary toxicity. In the absence of NQO1 as can occur by genetic mutation, the human airway is protected from harmful effects of ozone. We recently reported that NQO1-null mice are protected from airway hyperresponsiveness and pulmonary inflammation following ozone exposure. However, NQO1 regenerates intracellular antioxidants and therefore should protect the individual from oxidative stress. To explain this paradox, we tested whether in the absence of NQO1 ozone exposure results in increased generation of A2-isoprostane, a cyclopentenone isoprostane that blunts inflammation. Using GC-MS, we found that NQO1-null mice had greater lung tissue levels of D2- and E2-isoprostanes, the precursors of J2- and A2-isoprostanes, both at base line and following ozone exposure compared with congenic wild-type mice. We confirmed in primary cultures of normal human bronchial epithelial cells that A2-isoprostane inhibited ozone-induced NF-κB activation and IL-8 regulation. Furthermore, we determined that A2-isoprostane covalently modified the active Cys179 domain in inhibitory κB kinase in the presence of ozone in vitro, thus establishing the biochemical basis for A2-isoprostane inhibition of NF-κB. Our results demonstrate that host factors may regulate pulmonary susceptibility to ozone by regulating the generation of A2-isoprostanes in the lung. These observations provide the biochemical basis for the epidemiologic observation that NQO1 regulates pulmonary susceptibility to ozone. PMID:23275341

  19. NADPH:quinone oxidoreductase 1 regulates host susceptibility to ozone via isoprostane generation.

    PubMed

    Kummarapurugu, Apparao B; Fischer, Bernard M; Zheng, Shuo; Milne, Ginger L; Ghio, Andrew J; Potts-Kant, Erin N; Foster, W Michael; Soderblom, Erik J; Dubois, Laura G; Moseley, M Arthur; Thompson, J Will; Voynow, Judith A

    2013-02-15

    NADPH:quinone oxidoreductase 1 (NQO1) is recognized as a major susceptibility gene for ozone-induced pulmonary toxicity. In the absence of NQO1 as can occur by genetic mutation, the human airway is protected from harmful effects of ozone. We recently reported that NQO1-null mice are protected from airway hyperresponsiveness and pulmonary inflammation following ozone exposure. However, NQO1 regenerates intracellular antioxidants and therefore should protect the individual from oxidative stress. To explain this paradox, we tested whether in the absence of NQO1 ozone exposure results in increased generation of A(2)-isoprostane, a cyclopentenone isoprostane that blunts inflammation. Using GC-MS, we found that NQO1-null mice had greater lung tissue levels of D(2)- and E(2)-isoprostanes, the precursors of J(2)- and A(2)-isoprostanes, both at base line and following ozone exposure compared with congenic wild-type mice. We confirmed in primary cultures of normal human bronchial epithelial cells that A(2)-isoprostane inhibited ozone-induced NF-κB activation and IL-8 regulation. Furthermore, we determined that A(2)-isoprostane covalently modified the active Cys(179) domain in inhibitory κB kinase in the presence of ozone in vitro, thus establishing the biochemical basis for A(2)-isoprostane inhibition of NF-κB. Our results demonstrate that host factors may regulate pulmonary susceptibility to ozone by regulating the generation of A(2)-isoprostanes in the lung. These observations provide the biochemical basis for the epidemiologic observation that NQO1 regulates pulmonary susceptibility to ozone.

  20. Selective photocytotoxicity of anthrols on cancer stem-like cells: The effect of quinone methides or reactive oxygen species.

    PubMed

    Uzelac, Lidija; Škalamera, Đani; Mlinarić-Majerski, Kata; Basarić, Nikola; Kralj, Marijeta

    2017-09-08

    Cancer stem cells (CSCs) are a subpopulation of cancer cells that share properties of embryonic stem cells like pluripotency and self-renewal and show increased resistance to chemo- and radiotherapy. Targeting CSC, rather than cancer cells in general, is a novel and promising strategy for cancer treatment. Novel therapeutic approaches, such as photodynamic therapy (PDT) have been investigated. A promising group of phototherapeutic agents are reactive intermediates - quinone methides (QMs). This study describes preparation of QM precursor, 2-hydroxy-3-hydroxymethylanthracene (2) and a detailed photochemical and photobiological investigation on similar anthracene derivatives 3 and 4. Upon photoexcitation with near visible light at λ > 400 nm 1 and 2 give QMs, that were detected by laser flash photolysis and their reactivity with nucleophiles has been demonstrated in the preparative irradiation experiments where the corresponding adducts were isolated and characterized. 3 and 4 cannot undergo photodehydration and deliver QM, but lead to the formation of phenoxyl radical and singlet oxygen, respectively. The activity of 1-4 was tested on a panel of human tumor cell lines, while special attention was devoted to demonstrate their potential selectivity towards the cells with CSC-like properties (HMLEshEcad). Upon the irradiation of cell lines treated with 1-4, an enhancement of antiproliferative activity was demonstrated, but the DNA was not the target molecule. Confocal microscopy revealed that these compounds entered the cell and, upon irradiation, reacted with cellular membranes. Our experiments demonstrated moderate selectivity of 2 and 4 towards CSC-like cells, while necrosis was shown to be a dominant cell death mechanism. Especially interesting was the selectivity of 4 that produced higher levels of ROS in CSC-like cells, which forms the basis for further research on cancer phototherapy, as well as for the elucidation of the underlying mechanism of the observed

  1. ortho-Quinone methides as key intermediates in cascade heterocyclizations

    NASA Astrophysics Data System (ADS)

    Osipov, D. V.; Osyanin, V. A.; Klimochkin, Yu N.

    2017-07-01

    Development of new methods of heterocyclic synthesis is still a topical issue. In this connection, the trend related to the use of highly reactive o-quinone methides for the synthesis and functionalization of heterocycles appears rather promising. Since most of o-quinone methides are unstable, the choice of precursors and generation conditions is highly important for subsequent transformations involving them. Various methods of generation of o-quinone methides and cascade heterocyclizations in which the formation of these compounds is a key step are surveyed in the review. The trends of using o-quinone methides in the synthesis of various heterocycles are analyzed and the heterocyclization reactions involving these compounds are classified. The bibliography includes 395 references.

  2. Inhibition of reverse transcriptase by tyrosinase generated quinones related to levodopa and dopamine.

    PubMed

    Wick, M M; Fitzgerald, G

    1981-12-01

    Several derivatives of levodopa have been shown to be potent inhibitors of the sulfhydryl enzyme, RNA dependent DNA polymerase, reverse transcriptase (RT). In the presence of the polyphenol oxidase, tyrosinase, the inhibitory values were between 10(-6) M and 10(-5) M. Structure-activity studies revealed that active oxidation or reduction was necessary for this potent inhibitory response. Spectrophotometric analysis showed that the presence of both the quinone and quinol was required for maximum inhibitory activity. These data suggest that the common intermediate of oxidation of quinols or reduction of quinones (i.e., semiquinone) is the active species. The use of tyrosinase provides a convenient model for the detection of the actual inhibitory interaction of a free-radical (semiquinone) with a biologically important macromolecule, reverse transcriptase.

  3. 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

  4. Quinone Photoreactivity: An Undergraduate Experiment in Photochemistry

    ERIC Educational Resources Information Center

    Vaughan, Pamela P.; Cochran, Michael; Haubrich, Nicole

    2010-01-01

    An experiment exploring the photochemical properties of quinones was developed. Their unique photochemistry and highly reactive nature make them an ideal class of compounds for examining structure-activity relationships. For several substituted quinones, photochemical reactivity was related to structure and ultimately to the Gibbs energy for…

  5. Quinone Photoreactivity: An Undergraduate Experiment in Photochemistry

    ERIC Educational Resources Information Center

    Vaughan, Pamela P.; Cochran, Michael; Haubrich, Nicole

    2010-01-01

    An experiment exploring the photochemical properties of quinones was developed. Their unique photochemistry and highly reactive nature make them an ideal class of compounds for examining structure-activity relationships. For several substituted quinones, photochemical reactivity was related to structure and ultimately to the Gibbs energy for…

  6. Bifunctional squaramide-catalyzed synthesis of chiral dihydrocoumarins via ortho-quinone methides generated from 2-(1-tosylalkyl)phenols.

    PubMed

    Zhou, Ji; Wang, Mao-Lin; Gao, Xiang; Jiang, Guo-Fang; Zhou, Yong-Gui

    2017-03-23

    A bifunctional squaramide-catalyzed reaction of azlactones with o-quinone methides in situ generated from 2-(1-tosylalkyl)-phenols has been successfully developed under basic conditions, providing an efficient and mild access to chiral dihydrocoumarins bearing adjacent tertiary and quaternary stereogenic centers in high yields with excellent diastereo- and enantioselectivities.

  7. Remote position substituents as modulators of conformational and reactive properties of quinones. Relevance of the pi/pi intramolecular interaction.

    PubMed

    Roura-Pérez, Guillermo; Quiróz, Beatriz; Aguilar-Martínez, Martha; Frontana, Carlos; Solano, Alejandro; Gonzalez, Ignacio; Bautista-Martínez, José Antonio; Jiménez-Barbero, Jesús; Cuevas, Gabriel

    2007-03-16

    Several studies have described that quinoid rings with electron-rich olefins at remote position experience changes in their redox potential. Since the original description of these changes, different approaches have been developed to describe the properties of the binding sites of ubiquinones. The origin of this phenomenon has been attributed to lateral chain flexibility and its effect on the recognition between proteins and substrates associated with their important biological activity. The use of electrochemical-electron spin resonance (EC-ESR) assays and theoretical calculations at MP2/6-31G(d,p) and MP2/6-31++G(d,p)//MP2/6-31G(d,p) levels of several conformers of perezone [(2-(1,5-dimethyl-4-hexenyl)-3-hydroxy-5-methyl-1,4-benzoquinone] established that a weak pi-pi interaction controls not only the molecular conformation but also its diffusion coefficient and electrochemical properties. An analogous interaction can be suggested as the origin of similar properties of ubiquinone Q10. The use of nuclear magnetic resonance rendered, for the first time, direct evidence of the participation of different perezone conformers in solution and explained the cycloaddition process observed when the aforementioned quinone is heated to form pipitzols, sesquiterpenes with a cedrene skeleton. The fact that biological systems can modulate the redox potential of this type of quinones depending on the conformer recognized by an enzyme during a biological transformation is of great relevance.

  8. 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.

  9. Role of the Na(+)-translocating NADH:quinone oxidoreductase in voltage generation and Na(+) extrusion in Vibrio cholerae.

    PubMed

    Vorburger, Thomas; Nedielkov, Ruslan; Brosig, Alexander; Bok, Eva; Schunke, Emina; Steffen, Wojtek; Mayer, Sonja; Götz, Friedrich; Möller, Heiko M; Steuber, Julia

    2016-04-01

    For Vibrio cholerae, the coordinated import and export of Na(+) is crucial for adaptation to habitats with different osmolarities. We investigated the Na(+)-extruding branch of the sodium cycle in this human pathogen by in vivo (23)Na-NMR spectroscopy. The Na(+) extrusion activity of cells was monitored after adding glucose which stimulated respiration via the Na(+)-translocating NADH:quinone oxidoreductase (Na(+)-NQR). In a V. cholerae deletion mutant devoid of the Na(+)-NQR encoding genes (nqrA-F), rates of respiratory Na(+) extrusion were decreased by a factor of four, but the cytoplasmic Na(+) concentration was essentially unchanged. Furthermore, the mutant was impaired in formation of transmembrane voltage (ΔΨ, inside negative) and did not grow under hypoosmotic conditions at pH8.2 or above. This growth defect could be complemented by transformation with the plasmid encoded nqr operon. In an alkaline environment, Na(+)/H(+) antiporters acidify the cytoplasm at the expense of the transmembrane voltage. It is proposed that, at alkaline pH and limiting Na(+) concentrations, the Na(+)-NQR is crucial for generation of a transmembrane voltage to drive the import of H(+) by electrogenic Na(+)/H(+) antiporters. Our study provides the basis to understand the role of the Na(+)-NQR in pathogenicity of V. cholerae and other pathogens relying on this primary Na(+) pump for respiration. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. 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.

  11. A Catalyst-Controlled Aerobic Coupling of ortho-Quinones and Phenols Applied to the Synthesis of Aryl Ethers.

    PubMed

    Huang, Zheng; Lumb, Jean-Philip

    2016-09-12

    ortho-Quinones are underutilized six-carbon-atom building blocks. We herein describe an approach for controlling their reactivity with copper that gives rise to a catalytic aerobic cross-coupling with phenols. The resulting aryl ethers are generated in high yield across a broad substrate scope under mild conditions. This method represents a unique example where the covalent modification of an ortho-quinone is catalyzed by a transition metal, creating new opportunities for their utilization in synthesis.

  12. Deep Learning to Predict the Formation of Quinone Species in Drug Metabolism.

    PubMed

    Hughes, Tyler B; Swamidass, S Joshua

    2017-02-20

    Many adverse drug reactions are thought to be caused by electrophilically reactive drug metabolites that conjugate to nucleophilic sites within DNA and proteins, causing cancer or toxic immune responses. Quinone species, including quinone-imines, quinone-methides, and imine-methides, are electrophilic Michael acceptors that are often highly reactive and comprise over 40% of all known reactive metabolites. Quinone metabolites are created by cytochromes P450 and peroxidases. For example, cytochromes P450 oxidize acetaminophen to N-acetyl-p-benzoquinone imine, which is electrophilically reactive and covalently binds to nucleophilic sites within proteins. This reactive quinone metabolite elicits a toxic immune response when acetaminophen exceeds a safe dose. Using a deep learning approach, this study reports the first published method for predicting quinone formation: the formation of a quinone species by metabolic oxidation. We model both one- and two-step quinone formation, enabling accurate quinone formation predictions in nonobvious cases. We predict atom pairs that form quinones with an AUC accuracy of 97.6%, and we identify molecules that form quinones with 88.2% AUC. By modeling the formation of quinones, one of the most common types of reactive metabolites, our method provides a rapid screening tool for a key drug toxicity risk. The XenoSite quinone formation model is available at http://swami.wustl.edu/xenosite/p/quinone .

  13. Rethinking Dithiothreitol-Based Particulate Matter Oxidative Potential: Measuring Dithiothreitol Consumption versus Reactive Oxygen Species Generation.

    PubMed

    Xiong, Qianshan; Yu, Haoran; Wang, Runran; Wei, Jinlai; Verma, Vishal

    2017-06-06

    We measured the rate of generation of reactive oxygen species (ROS) [hydroxyl radicals ((•)OH) and hydrogen peroxide (H2O2)] catalyzed by ambient particulate matter (PM) in the dithiothreitol (DTT) assay. To understand the mechanism of ROS generation, we tested several redox-active substances, such as 9,10-phenanthrenequinone (PQ), 5-hydroxy-1,4-naphthoquinone (5H-1,4NQ), 1,2-naphthoquinone (1,2-NQ), 1,4-naphthoquinone (1,4-NQ), copper(II), manganese(II), and iron (II and III). Both pure compounds and their mixtures show different patterns in DTT oxidation versus ROS generation. The quinones, known to oxidize DTT in the efficiency order of PQ > 5H-1,4NQ > 1,2-NQ > 1,4-NQ, show a different efficiency order (5H-1,4NQ > 1,2-NQ ≈ PQ > 1,4-NQ) in the ROS generation. Cu(II), a dominant metal in DTT oxidation, contributes almost negligibly to the ROS generation. Fe is mostly inactive in DTT oxidation, but shows synergistic effect in (•)OH formation in the presence of other quinones (mixture/sum > 1.5). Ten ambient PM samples collected from an urban site were analyzed, and although DTT oxidation was significantly correlated with H2O2 generation (Pearson's r = 0.91), no correlation was observed between DTT oxidation and (•)OH formation. Our results show that measuring both DTT consumption and ROS generation in the DTT assay is important to incorporate the synergistic contribution from different aerosol components and to provide a more inclusive picture of the ROS activity of ambient PM.

  14. Quinone Reductase Induction as a Biomarker for Cancer Chemoprevention⊥

    PubMed Central

    Cuendet, Muriel; Oteham, Carol P.; Moon, Richard C.; Pezzuto, John M.

    2007-01-01

    Chemoprevention involves the use of natural or synthetic substances to reduce the risk of developing cancer. Strategies for protecting cells from initiation events include decreasing metabolic enzymes responsible for generating reactive species (phase I enzymes) while increasing phase II enzymes that can deactivate radicals and electrophiles known to intercede in normal cellular processes. Reduction of electrophilic quinones by quinone reductase is an important detoxification pathway. Following evaluation of approximately 3000 plant and marine organism extracts, the number characterized as “active” was established in the range of 12% of the total, and over 60 active compounds have been isolated as quinone reductase inducers. One of them, isoliquiritigenin (1), isolated from tonka bean, was shown to be a monofunctional inducer by having similar quinone reductase inducing ability in wild-type Hepa 1c1c7 cells and two mutant cell lines. To further investigate the mechanism of induction, HepG2 human hepatoma cells stably transfected with ARE-luciferase plasmid were used. Isoliquiritigenin (1) significantly induced the luciferase activity in a dose-dependent manner. On the basis of these results, a full-term cancer chemoprevention study was conducted with 7,12-dimethylbenz[a]anthracene (DMBA)-treated female Sprague-Dawley rats. Dietary administration of 1 increased tumor latency. Based on these promising preliminary results, additional mechanistic studies are underway, as well as full-term carcinogenesis studies with chronic administration schedules. PMID:16562858

  15. Lung toxicity and tumor promotion by hydroxylated derivatives of 2,6-di-tert-butyl-4-methylphenol (BHT) and 2-tert-butyl-4-methyl-6-iso-propylphenol: correlation with quinone methide reactivity.

    PubMed

    Kupfer, Rene; Dwyer-Nield, Lori D; Malkinson, Alvin M; Thompson, John A

    2002-08-01

    Acute pulmonary toxicity and tumor promotion by the food additive 2,6-di-tert-butyl-4-methylphenol (BHT) in mice are well documented. These effects have been attributed to either of two quinone methides, 2,6-di-tert-butyl-4-methylenecyclohexa-2,5-dienone (BHT-QM) formed through direct oxidation of BHT by pulmonary cytochrome P450 or a quinone methide formed by hydroxylation of a tert-butyl group of BHT (to form BHTOH) followed by oxidation of this metabolite to BHTOH-QM. BHTOH-QM is a more reactive electrophile compared to BHT-QM due to intramolecular interactions of the side-chain hydroxyl with the carbonyl oxygen. To further examine this bioactivation pathway, an analogue of BHTOH was prepared, 2-tert-butyl-6-(1'-hydroxy-1'-methyl)ethyl-4-methylphenol (BPPOH), that is structurally very similar to BHTOH but forms a quinone methide (BPPOH-QM) capable of more efficient intramolecular hydrogen bonding and, therefore, higher electrophilicity than BHTOH-QM. BPPOH-QM was synthesized and its reactivity with water, methanol, and glutathione determined to be >10-fold higher than that of BHTOH-QM. The conversions of BPPOH and BHTOH to quinone methides in lung microsomes from male BALB/cByJ mice were quantitatively similar, but in vivo the former was pneumotoxic at one-half of the dose required for the latter and one-eighth of the dose required for BHT, as determined by increased lung weight:body weight ratios following a single i.p. injection. Similar differences were found in the doses of BHT, BHTOH, or BPPOH required for tumor promotion after a single initiating dose of 3-methylcholanthrene followed by three weekly injections of the phenol. The downregulaton of calpain II, previously shown to accompany lung tumor promotion by BHT and BHTOH, also occurred with BPPOH. The correlation between biologic activities of these phenols and the reactivities of their corresponding quinone methides provides additional support for the role of BHTOH-QM as the principal metabolite

  16. The Role of Human Aldo-Keto Reductases in the Metabolic Activation and Detoxication of Polycyclic Aromatic Hydrocarbons: Interconversion of PAH Catechols and PAH o-Quinones.

    PubMed

    Zhang, Li; Jin, Yi; Huang, Meng; Penning, Trevor M

    2012-01-01

    Polycyclic aromatic hydrocarbons (PAH) are ubiquitous environmental pollutants. They are procarcinogens requiring metabolic activation to elicit their deleterious effects. Aldo-keto reductases (AKR) catalyze the oxidation of proximate carcinogenic PAH trans-dihydrodiols to yield electrophilic and redox-active PAH o-quinones. AKRs are also found to be capable of reducing PAH o-quinones to form PAH catechols. The interconversion of o-quinones and catechols results in the redox-cycling of PAH o-quinones to give rise to the generation of reactive oxygen species and subsequent oxidative DNA damage. On the other hand, PAH catechols can be intercepted through phase II metabolism by which PAH o-quinones could be detoxified and eliminated. The aim of the present review is to summarize the role of human AKRs in the metabolic activation/detoxication of PAH and the relevance of phase II conjugation reactions to human lung carcinogenesis.

  17. Evidence for the generation of reactive oxygen species from hydroquinone and benzoquinone: Roles in arsenite oxidation.

    PubMed

    Qin, Wenxiu; Wang, Yujun; Fang, Guodong; Wu, Tongliang; Liu, Cun; Zhou, Dongmei

    2016-05-01

    Natural organic matter (NOM) significantly affects the fate, bioavailability, and toxicity of arsenic in the environment. In the present study, we investigated the oxidation of As(III) in the presence of hydroquinone (HQ) and benzoquinone (BQ), which were selected as model quinone moieties for NOM. It was found that As(III) was oxidized to As(V) in the presence of HQ or BQ at neutral conditions, and the oxidation efficiency of As(III) increased from 33% to 92% in HQ solutions and from 0 to 80% in BQ solutions with pH increasing from 6.5 to 8.5. The oxidation mechanism was further explored with electron spin resonance (ESR) technique. The results showed that semiquinone radicals (SQ(-)) were generated from the comproportionation reaction between BQ and HQ, which mediated the formation of superoxide anion (O2(-)), hydrogen peroxide (H2O2) and hydroxyl radical (OH). Both the SQ(-), H2O2 and OH contributed to the oxidation of As(III). The increase of pH favored the formation of SQ(-), and thus promoted the generation of reactive oxygen species (ROS) as well as As(III) oxidation. Increasing concentrations of HQ and BQ from 0.1 to 1.0 mM enhanced As(III) oxidation from 65% to 94% and from 10% to 53%, respectively. The findings of this study facilitate our understanding of the fate and transformation of As(III) in organic-rich aquatic environments and highlight quinone moieties as the potential oxidants for As(III) in the remediation of arsenic contaminated sites.

  18. Quinone Reductase 2 Is a Catechol Quinone Reductase

    SciTech Connect

    Fu, Yue; Buryanovskyy, Leonid; Zhang, Zhongtao

    2008-09-05

    The functions of quinone reductase 2 have eluded researchers for decades even though a genetic polymorphism is associated with various neurological disorders. Employing enzymatic studies using adrenochrome as a substrate, we show that quinone reductase 2 is specific for the reduction of adrenochrome, whereas quinone reductase 1 shows no activity. We also solved the crystal structure of quinone reductase 2 in complexes with dopamine and adrenochrome, two compounds that are structurally related to catecholamine quinones. Detailed structural analyses delineate the mechanism of quinone reductase 2 specificity toward catechol quinones in comparison with quinone reductase 1; a side-chain rotational difference between quinone reductase 1 and quinone reductase 2 of a single residue, phenylalanine 106, determines the specificity of enzymatic activities. These results infer functional differences between two homologous enzymes and indicate that quinone reductase 2 could play important roles in the regulation of catecholamine oxidation processes that may be involved in the etiology of Parkinson disease.

  19. Generation of reactive oxygen species by leukocytes of Prochilodus lineatus.

    PubMed

    de Faria, Marcos Tucunduva; Cury-Boaventura, Maria Fernanda; Lopes, Lucia Rossetti; da Silva, José Roberto Machado Cunha

    2014-04-01

    Prochilodus lineatus (curimbatá), from the Procholodontidae family, is a Brazilian freshwater fish, which is important commercially, nutritionally and ecologically. It is encountered in the Rio da Prata Bay in Southern South America. Studies on the immune system of this fish are scarce, but the physiological mechanisms of the species are analogous to those of other vertebrates. Thus, this work discusses the present study, which correlates P. lineatus leukocytes and the generation of reactive oxygen species after modulatory stimuli. Leukocytes were characterized by light and electron transmission microscopy and investigated by the generation of H2O2 and O2 (-), using phenol red, flow-cytometry and electron transmission histochemistry. The study determined that monocytes and neutrophils are the main cells responsible for generating O2 after stimulation with phorbol myristate acetate. Superoxide dismutase successfully inhibited the generation of reactive oxygen species in neutrophils and monocytes, but stimulated generation when in association with phorbol myristate acetate. Fish leukocyte samples from P. lineatus showed cross-reactivity with antibodies directed against human NADPH-oxidase antibody subunits (p47(phox) and p67(phox)). Thus, catalase enhanced the presence of p47(phox). Neutrophil mitochondria were shown to be generators of H2O2 (charged by cerium precipitate), being enlarged and changing their format. The present study contributes to a better understanding of the respiratory burst pathways in this species and suggests mitochondria as the organelle responsible for generation of reactive oxygen species.

  20. Generation, structure and reactivity of tertiary organolithium reagents.

    PubMed

    Perry, Matthew A; Rychnovsky, Scott D

    2015-04-01

    Tertiary alkyllithium reagents are very useful intermediates in synthesis. Alkyllithium reagents with adjacent heteroatoms may be formed stereoselectively or may react stereoselectively, and have been used in the synthesis of alkaloids, C-glycosides and spirocycles. An overview of the generation, reactivity and stereochemistry of tertiary alkyllithium reagents will be presented, as well as examples of their use in organic synthesis. The discussion will be focused on a conceptual understanding of the generation and reactivity of these intermediates. The reactions described herein generate fully substituted carbon atoms, and the forces driving stereoselectivity will be discussed in detail. Where appropriate, computational results will be introduced to provide a better understanding for the structure and reactivity of tertiary alkyllithium reagents.

  1. Local control of reactive power by distributed photovoltaic generators

    SciTech Connect

    Chertkov, Michael; Turitsyn, Konstantin; Sulc, Petr; Backhaus, Scott

    2010-01-01

    High penetration levels of distributed photovoltaic (PV) generation on an electrical distribution circuit may severely degrade power quality due to voltage sags and swells caused by rapidly varying PV generation during cloud transients coupled with the slow response of existing utility compensation and regulation equipment. Although not permitted under current standards for interconnection of distributed generation, fast-reacting, VAR-capable PV inverters may provide the necessary reactive power injection or consumption to maintain voltage regulation under difficult transient conditions. As side benefit, the control of reactive power injection at each PV inverter provides an opportunity and a new tool for distribution utilities to optimize the performance of distribution circuits, e.g. by minimizing thermal losses. We suggest a local control scheme that dispatches reactive power from each PV inverter based on local instantaneous measurements of the real and reactive components of the consumed power and the real power generated by the PVs. Using one adjustable parameter per circuit, we balance the requirements on power quality and desire to minimize thermal losses. Numerical analysis of two exemplary systems, with comparable total PV generation albeit a different spatial distribution, show how to adjust the optimization parameter depending on the goal. Overall, this local scheme shows excellent performance; it's capable of guaranteeing acceptable power quality and achieving significant saving in thermal losses in various situations even when the renewable generation in excess of the circuit own load, i.e. feeding power back to the higher-level system.

  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. Formation and Biological Targets of Quinones: Cytotoxic versus Cytoprotective Effects

    PubMed Central

    2016-01-01

    Quinones represent a class of toxicological intermediates, which can create a variety of hazardous effects in vivo including, acute cytotoxicity, immunotoxicity, and carcinogenesis. In contrast, quinones can induce cytoprotection through the induction of detoxification enzymes, anti-inflammatory activities, and modification of redox status. The mechanisms by which quinones cause these effects can be quite complex. The various biological targets of quinones depend on their rate and site of formation and their reactivity. Quinones are formed through a variety of mechanisms from simple oxidation of catechols/hydroquinones catalyzed by a variety of oxidative enzymes and metal ions to more complex mechanisms involving initial P450-catalyzed hydroxylation reactions followed by two-electron oxidation. Quinones are Michael acceptors, and modification of cellular processes could occur through alkylation of crucial cellular proteins and/or DNA. Alternatively, quinones are highly redox active molecules which can redox cycle with their semiquinone radical anions leading to the formation of reactive oxygen species (ROS) including superoxide, hydrogen peroxide, and ultimately the hydroxyl radical. Production of ROS can alter redox balance within cells through the formation of oxidized cellular macromolecules including lipids, proteins, and DNA. This perspective explores the varied biological targets of quinones including GSH, NADPH, protein sulfhydryls [heat shock proteins, P450s, cyclooxygenase-2 (COX-2), glutathione S-transferase (GST), NAD(P)H:quinone oxidoreductase 1, (NQO1), kelch-like ECH-associated protein 1 (Keap1), IκB kinase (IKK), and arylhydrocarbon receptor (AhR)], and DNA. The evidence strongly suggests that the numerous mechanisms of quinone modulations (i.e., alkylation versus oxidative stress) can be correlated with the known pathology/cytoprotection of the parent compound(s) that is best described by an inverse U-shaped dose–response curve. PMID:27617882

  4. 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

  5. Chemical reactivity as a tool to study carcinogenicity: reaction between estradiol and estrone 3,4-quinones ultimate carcinogens and guanine.

    PubMed

    Huetz, Ph; Kamarulzaman, E E; Wahab, H A; Mavri, J

    2004-01-01

    In this article we study the chemical reactions between guanine and two ultimate carcinogens, the 3,4-quinone forms of the estrogens estrone (E1) and estradiol (E2). DNA was truncated to guanine, i.e. no deoxyribose moiety was included. Due to a complex reaction that involves proton transfer via water molecules we applied linear free energy relationships rather than computation of the transition state and activation energies. The minima corresponding to reactants and products were obtained on the B3LYP/6-31G(d) level. The effects of hydration were considered using the solvent reaction field of Tomasi and co-workers and the Langevin dipoles model of Florian and Warshel. No significant difference in reaction free energy for the reaction involving estrone and estradiol metabolites was found, despite the fact that for the two substances different carcinogenic activities were reported. Differences in carcinogenicity may be therefore attributed to other types of interactions or reactions such as (i) specific interactions of the carbonyl or hydroxyl group with DNA giving rise to different activation free energies for the reactions, (ii) the reaction of depurination and subsequent effects on the DNA, (iii) enzymatic or nonenzymatic oxidation steps (P450, aromatase, peroxidases, O2) and detoxification reactions (catechol-O-methyl transferase, S-transferase), or (iv) binding of the hormone to its nuclear receptors.

  6. Theoretical study of the adsorption of DOPA-quinone and DOPA-quinone chlorides on Cu (1 0 0) surface

    NASA Astrophysics Data System (ADS)

    Chen, Shuang-Kou; Wang, Bo-Chu; Zhou, Tai-Gang; Huang, Wen-Zhang

    2011-07-01

    The marine mussel secreted adhesive proteins and could bind strongly to all kinds of surfaces. Studies indicated that there was an unusual amino acid 3,4-dihydroxy-L-phenylanine (DOPA). DOPA could be oxidized to DOPA-quinone easily, which had a superior ability to on surface directly. The technology of electrolyzing seawater was employed to generate HOCl solution to react with DOPA-quinone and form DOPA-quinone chlorides (DOPA-quinone-Cl) to hinder the adhesion. However, the detailed hinder-mechanism remained unknown to be fully explained. Herein, using quantum chemical density functional theory methods, we have systematically studied three kinds of adsorption for DOPA-quinone and DOPA-quinone-Cl on Cu (1 0 0) surface: hydroxyl oxygen-side vertical, carbonyl oxygen-side vertical, amino N-terminal vertical adsorptions and carried out geometry optimization and energy calculation. The results showed that two molecules could absorb on the Cu (1 0 0) through hydroxyl oxygen-side vertical adsorption, while the other two kinds of adsorption could not form an effective adsorption. Calculations of adsorption energy for hydroxyl oxygen-side vertical adsorption indicated that: after HOCl modification, adsorption energy decreased from -247.2310 kJ/mol to -177.0579 kJ/mol for DOPA-quinone and DOPA-quinone-Cl; and the Mulliken Charges Populations showed that the electrons transferred from surface to DOPA-quinone-Cl was less than that to DOPA-quinone, namely, the fewer the number of electrons transferred, the weaker interaction between molecular and surface. After the theoretical calculation, we found that the anti-foul goal had been achieved by electrolysis of seawater to generate HOCl to modify DOPA-quinone, which led to the reduction of adsorption energy and transferred electrons.

  7. Bacterial growth response to photoactive quinones.

    PubMed

    Vaughan, Pamela P; Novotny, Paul; Haubrich, Nicole; McDonald, Luther; Cochran, Michael; Serdula, Julia; Amin, Raid W; Jeffrey, Wade H

    2010-01-01

    Quinones are known producers of reactive oxygen species (ROS) that may be toxic in natural aquatic environments. In this study, the effects of parent quinones and their photodegradation products on bacterial growth were determined, and photochemical ROS formation rates were measured. Using (3)H-leucine incorporation to measure growth of the bacterium Pseudomonas aeruginosa and natural seawater bacterioplankton, growth inhibition was observed when samples were exposed to dichlone, chloranil and sodium anthraquinone-2-sulfonate (AQ2S). For seawater, compared with other quinones tested, dichlone showed the greatest toxicity in the dark, and AQ2S toxicity was greatest during simultaneous exposure to sunlight. Photodegraded chloranil and dichlone showed decreased toxicity compared with nonirradiated samples. For P. aeruginosa, AQ2S and its photodegradation products showed the greatest toxicity during simultaneous exposure to sunlight. Chloranil photodegradation products showed reduced toxicity compared with the parent compound during simultaneous exposure to sunlight. Dichlone was the only compound to show any toxicity to P. aeruginosa in the dark, and its photodegradation products were more toxic than the parent compound. Based on the results of dark and light controlled experiments measuring bacterial growth and estimated ROS production rates, ROS alone does not account for relative differences in toxicity between these quinones. © 2010 The Authors. Journal Compilation. The American Society of Photobiology.

  8. 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

  9. Magnetic nanoparticles: reactive oxygen species generation and potential therapeutic applications

    NASA Astrophysics Data System (ADS)

    Mai, Trang; Hilt, J. Zach

    2017-07-01

    Magnetic nanoparticles have been demonstrated to produce reactive oxygen species (ROS), which play a major role in various cellular pathways, via Fenton and Haber-Weiss reaction. ROS act as a double-edged sword inside the body. At normal conditions, the generation of ROS is in balance with their elimination by scavenger systems, and they can promote cell proliferation as well as differentiation. However, at an increased level, they can cause damages to protein, lead to cellular apoptosis, and contribute to many diseases including cancer. Many recent studies proposed a variety of strategies to either suppress toxicity of ROS generation or exploit the elevated ROS levels for cancer therapy.

  10. NQO2 Is a Reactive Oxygen Species Generating Off-Target for Acetaminophen

    PubMed Central

    2014-01-01

    The analgesic and antipyretic compound acetaminophen (paracetamol) is one of the most used drugs worldwide. Acetaminophen overdose is also the most common cause for acute liver toxicity. Here we show that acetaminophen and many structurally related compounds bind quinone reductase 2 (NQO2) in vitro and in live cells, establishing NQO2 as a novel off-target. NQO2 modulates the levels of acetaminophen derived reactive oxygen species, more specifically superoxide anions, in cultured cells. In humans, NQO2 is highly expressed in liver and kidney, the main sites of acetaminophen toxicity. We suggest that NQO2 mediated superoxide production may function as a novel mechanism augmenting acetaminophen toxicity. PMID:25313982

  11. NQO2 is a reactive oxygen species generating off-target for acetaminophen.

    PubMed

    Miettinen, Teemu P; Björklund, Mikael

    2014-12-01

    The analgesic and antipyretic compound acetaminophen (paracetamol) is one of the most used drugs worldwide. Acetaminophen overdose is also the most common cause for acute liver toxicity. Here we show that acetaminophen and many structurally related compounds bind quinone reductase 2 (NQO2) in vitro and in live cells, establishing NQO2 as a novel off-target. NQO2 modulates the levels of acetaminophen derived reactive oxygen species, more specifically superoxide anions, in cultured cells. In humans, NQO2 is highly expressed in liver and kidney, the main sites of acetaminophen toxicity. We suggest that NQO2 mediated superoxide production may function as a novel mechanism augmenting acetaminophen toxicity.

  12. Update of the NAD(P)H:quinone oxidoreductase (NQO) gene family

    PubMed Central

    2006-01-01

    The NAD(P)H:quinone acceptor oxidoreductase (NQO) gene family belongs to the flavoprotein clan and, in the human genome, consists of two genes (NQO1 and NQO2). These two genes encode cytosolic flavoenzymes that catalyse the beneficial two-electron reduction of quinones to hydroquinones. This reaction prevents the unwanted one-electron reduction of quinones by other quinone reductases; one-electron reduction results in the formation of reactive oxygen species, generated by redox cycling of semiquinones in the presence of molecular oxygen. Both the mammalian NQO1 and NQO2 genes are upregulated as a part of the oxidative stress response and are inexplicably overexpressed in particular types of tumours. A non-synonymous mutation in the NQO1 gene, leading to absence of enzyme activity, has been associated with an increased risk of myeloid leukaemia and other types of blood dyscrasia in workers exposed to benzene. NQO2 has a melatonin-binding site, which may explain the anti-oxidant role of melatonin. An ancient NQO3 subfamily exists in eubacteria and the authors suggest that there should be additional divisions of the NQO family to include the NQO4 subfamily in fungi and NQO5 subfamily in archaebacteria. Interestingly, no NQO genes could be identified in the worm, fly, sea squirt or plants; because these taxa carry quinone reductases capable of one- and two-electron reductions, there has been either convergent evolution or redundancy to account for the appearance of these enzyme functions whenever they have been needed during evolution. PMID:16595077

  13. Method for generating a highly reactive plasma for exhaust gas aftertreatment and enhanced catalyst reactivity

    DOEpatents

    Whealton, John H.; Hanson, Gregory R.; Storey, John M.; Raridon, Richard J.; Armfield, Jeffrey S.; Bigelow, Timothy S.; Graves, Ronald L.

    2002-01-01

    A method for non-thermal plasma aftertreatment of exhaust gases the method comprising the steps of providing short risetime, high frequency, high power bursts of low-duty factor microwaves sufficient to generate a plasma discharge and passing a gas to be treated through the discharge so as to cause dissociative reduction of the exhaust gases and enhanced catalyst reactivity through application of the pulsed microwave fields directly to the catalyst material sufficient to cause a polarizability catastrophe and enhanced heating of the metal crystallite particles of the catalyst, and in the presence or absence of the plasma. The invention also includes a reactor for aftertreatment of exhaust gases.

  14. Redox Cycling of Catechol Estrogens Generating Apurinic/Apyrimidinic Sites and 8-oxo-Deoxyguanosine via Reactive Oxygen Species Differentiates Equine and Human Estrogens

    PubMed Central

    Wang, Zhican; Chandrasena, Esala R.; Yuan, Yang; Peng, Kuan-wei; van Breemen, Richard B.; Thatcher, Gregory R. J.; Bolton, Judy L.

    2010-01-01

    Metabolic activation of estrogens to catechols and further oxidation to highly reactive o-quinones generates DNA damage including apurinic/apyrimidinic (AP) sites. 4-Hydroxyequilenin (4-OHEN) is the major catechol metabolite of equine estrogens present in estrogen replacement formulations, known to cause DNA strand breaks, oxidized bases, and stable and depurinating adducts. However, the direct formation of AP sites by 4-OHEN has not been characterized. In the present study, the induction of AP sites in vitro by 4-OHEN and the endogenous catechol estrogen metabolite, 4-hydroxyestrone (4-OHE) was examined by an aldehyde reactive probe assay. Both 4-OHEN and 4-OHE can significantly enhance the levels of AP sites in calf thymus DNA in the presence of the redox cycling agents, copper ion and NADPH. The B-ring unsaturated catechol 4-OHEN induced AP sites without added copper, whereas 4-OHE required copper. AP sites were also generated much more rapidly by 4-OHEN. For both catechol estrogens, the levels of AP sites correlated linearly with 8-oxo-dG levels, implying that depuriniation resulted from reactive oxygen species (ROS) rather than depurination of estrogen-DNA adducts. ROS modulators such as catalase which scavenges hydrogen peroxide and a Cu(I) chelator blocked the formation of AP sites. In MCF-7 breast cancer cells, 4-OHEN significantly enhanced the formation of AP sites with added NADH. In contrast, no significant induction of AP sites was detected in 4-OHE-treated cells. The greater redox activity of the equine catechol estrogen produces rapid oxidative DNA damage via ROS, which is enhanced by redox cycling agents and interestingly by NADPH-dependent quinone oxidoreductase (NQO1). PMID:20509668

  15. 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

  16. 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.

  17. Independent Generation and Reactivity of Thymidine Radical Cations.

    PubMed

    Sun, Huabing; Taverna Porro, Marisa L; Greenberg, Marc M

    2017-10-10

    Thymidine radical cation (1) is produced by ionizing radiation and has been invoked as an intermediate in electron transfer in DNA. Previous studies on its structure and reactivity have utilized thymidine as a precursor, which limits quantitative product analysis because thymidine is readily reformed from 1. In this investigation, radical cation 1 is independently generated via β-heterolysis of a pyrimidine radical generated photochemically from an aryl sulfide. Thymidine is the major product (33%) from 1 at pH 7.2. Diastereomeric mixtures of thymidine glycol and the corresponding 5-hydroxperoxides resulting from water trapping of 1 are formed. Significantly lower yields of products such as 5-formyl-2'-deoxyuridine that are ascribable to deprotonation from the C5-methyl group of 1 are observed. Independent generation of the N3-methyl analogue of 1 (NMe-1) produces considerably higher yields of products derived from water trapping, and these products are formed in much higher yields than those attributable to the C5-methyl group deprotonation in NMe-1. N3-Methyl-thymidine is, however, the major product and is produced in as high as 70% yield when the radical cation is produced in the presence of excess thiol. The effects of exogenous reagents on product distributions are consistent with the formation of diffusively free radical cations (1, NMe-1). This method should be compatible with producing radical cations at defined positions within DNA.

  18. Photosensitizing Nanoparticles and The Modulation of Reactive Oxygen Species generation

    NASA Astrophysics Data System (ADS)

    Tada, Dayane; Baptista, Mauricio

    2015-05-01

    The association of PhotoSensitizer (PS) molecules with nanoparticles (NPs) forming photosensitizing NPs, has emerged as a therapeutic strategy to improve PS tumor targeting, to protect PS from deactivation reactions and to enhance both PS solubility and circulation time. Since association with NPs usually alters PS photophysical and photochemical properties, photosensitizing NPs are an important tool to modulate reactive oxygen species (ROS) generation. Depending on the design of the photosensitizing NP, i.e., type of PS, the NP material and the method applied for the construction of the photosensitizing NP, the deactivation routes of the excited state can be controlled, allowing the generation of either singlet oxygen or other ROS. Controlling the type of generated ROS is desirable not only in biomedical applications, as in Photodynamic Therapy where the type of ROS affects therapeutic efficiency, but also in other technological relevant fields like energy conversion, where the electron and energy transfer processes are necessary to increase the efficiency of photoconversion cells. The current review highlights some of the recent developments in the design of Photosensitizing NPs aimed at modulating the primary photochemical events after light absorption.

  19. 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.

  20. Quantitative assessment of reactive oxygen sonochemically generated by cavitation bubbles

    NASA Astrophysics Data System (ADS)

    Yasuda, Jun; Miyashita, Takuya; Taguchi, Kei; Yoshizawa, Shin; Umemura, Shin-ichiro

    2015-07-01

    Acoustic cavitation bubbles can induce not only a thermal bioeffect but also a chemical bioeffect. When cavitation bubbles collapse and oscillate violently, they produce reactive oxygen species (ROS) that cause irreversible changes to the tissue. A sonosensitizer can promote such ROS generation. A treatment method using a sonosensitizer is called sonodynamic treatment. Rose bengal (RB) is one of the sonosensitizers whose in vivo and in vitro studies have been reported. In sonodynamic treatment, it is important to produce ROS at a high efficiency. For the efficient generation of ROS, a triggered high-intensity focused ultrasound (HIFU) sequence has been proposed. In this study, cavitation bubbles were generated in a chamber where RB solution was sealed, and a high-speed camera captured the behavior of these cavitation bubbles. The amount of ROS was also quantified by a potassium iodide (KI) method and compared with high-speed camera pictures to investigate the effectiveness of the triggered HIFU sequence. As a result, ROS could be obtained efficiently by this sequence.

  1. Plasma-generated reactive oxygen species for biomedical applications

    NASA Astrophysics Data System (ADS)

    Sousa, J. S.; Hammer, M. U.; Winter, J.; Tresp, H.; Duennbier, M.; Iseni, S.; Martin, V.; Puech, V.; Weltmann, K. D.; Reuter, S.

    2012-10-01

    To get a better insight into the effects of reactive oxygen species (ROS) on cellular components, fundamental studies are essential to determine the nature and concentration of plasma-generated ROS, and the chemistry induced in biological liquids by those ROS. In this context, we have measured the absolute density of the main ROS created in three different atmospheric pressure plasma sources: two geometrically distinct RF-driven microplasma jets (μ-APPJ [1] and kinpen [2]), and an array of microcathode sustained discharges [3]. Optical diagnostics of the plasma volumes and effluent regions have been performed: UV absorption for O3 and IR emission for O2(a^1δ) [4]. High concentrations of both ROS have been obtained (10^14--10^17cm-3). The effect of different parameters, such as gas flows and mixtures and power coupled to the plasmas, has been studied. For plasma biomedicine, the determination of the reactive species present in plasma-treated liquids is of great importance. In this work, we focused on the measurement of the concentration of H2O2 and NOX radicals, generated in physiological solutions like NaCl and PBS.[4pt] [1] N. Knake et al., J. Phys. D: App. Phys. 41, 194006 (2008)[0pt] [2] K.D. Weltmann et al., Pure Appl. Chem. 82, 1223 (2010)[0pt] [3] J.S. Sousa et al., Appl. Phys. Lett. 97, 141502 (2010)[0pt] [4] J.S. Sousa et al., Appl. Phys. Lett. 93, 011502 (2008)

  2. The Domestication of ortho-Quinone Methides

    PubMed Central

    2015-01-01

    Conspectus An ortho-quinone methide (o-QM) is a highly reactive chemical motif harnessed by nature for a variety of purposes. Given its extraordinary reactivity and biological importance, it is surprising how few applications within organic synthesis exist. We speculate that their widespread use has been slowed by the complications that surround the preparation of their precursors, the harsh generation methods, and the omission of this stratagem from computer databases due to its ephemeral nature. About a decade ago, we discovered a mild anionic triggering procedure to generate transitory o-QMs at low temperature from readily available salicylaldehydes, particularly OBoc derivatives. This novel reaction cascade included both the o-QM formation and the subsequent consumption reaction. The overall transformation was initiated by the addition of the organometallic reagent, usually a Grignard reagent, which resulted in the formation of a benzyloxy alkoxide. Boc migration from the neighboring phenol produced a magnesium phenoxide that we supposed underwent β-elimination of the transferred Boc residue to form an o-QM for immediate further reactions. Moreover, the cascade proved controllable through careful manipulation of metallic and temperature levers so that it could be paused, stopped, or restarted at various intermediates and stages. This new level of domestication enabled us to deploy o-QMs for the first time in a range of applications including diastereocontrolled reactions. This sequence ultimately could be performed in either multipot or single pot processes. The subsequent reaction of the fleeting o-QM intermediates included the 1,4-conjugate additions that led to unbranched or branched ortho-alkyl substituted phenols and Diels–Alder reactions that provided 4-unsubstituted or 4-substituted benzopyrans and chroman ketals. The latter cycloadducts were obtained for the first time with outstanding diastereocontrol. In addition, the steric effects of the newly

  3. Hurdles to organic quinone flow cells. Electrode passivation by quinone reduction in acetonitrile Li electrolytes

    NASA Astrophysics Data System (ADS)

    Rueda-García, D.; Dubal, D. P.; Huguenin, F.; Gómez-Romero, P.

    2017-05-01

    The uses of quinones in Redox Flow Batteries (RFBs) has been mainly circumscribed to aqueous solutions (of derivatives with polar groups) despite a larger solubility and wider electrochemical window provided by organic media. The redox mechanism of quinones in protic media is simpler and better known than in aprotic media, where radical species are involved. This paper reports the behaviour of methyl-p-benzoquinone (MBQ) under electrochemical reduction conditions in a LiClO4sbnd CH3CN electrolyte and various working electrodes. We detected the reversible generation of a bright green coating on the working electrode and the subsequent formation of a polymer (the nature of which depends on the presence or absence of oxygen). These coatings prevent the regular redox process of methyl-p-benzoquinone from taking place on the surface of the electrode and is generated regardless of the electrode material used or the presence of O2 in solution. In addition to MBQ, the green passivating layer was also found for less sterically hindered quinones such as p-benzoquinone or 1,4-naphthoquinone, but not for anthraquinone. We have also shown the central role of Li+ in the formation of this green layer. This work provides important guidelines for the final use of quinones in RFBs with organic electrolytes.

  4. Differential protein labeling based on electrochemically generated reactive intermediates.

    PubMed

    Büter, Lars; Faber, Helene; Wigger, Tina; Vogel, Martin; Karst, Uwe

    2015-10-06

    A specific labeling method for cysteine moieties in proteins was developed. Electrochemical oxidation of phenolic compounds such as phenol or acetaminophen leads to the generation of the reactive intermediates benzoquinone and N-acetyl-p-benzoquinone imine, which can subsequently react with nucleophilic thiol functions in peptides or proteins. Differential labeling of cysteine residues was successfully demonstrated with native as well as heavy-isotope labeled forms of the corresponding labeling compounds. The specific mass differences on the peptide level were successfully analyzed by mass spectrometry for the tripeptide glutathione. Free cysteines in various proteins such as β-lactoglobulin A, human serum albumin, hemoglobin, and human carbonic anhydrase I were successfully labeled. Tryptic digestion of differentially labeled carbonic anhydrase I and hemoglobin allowed the identification of the binding site in the proteins. The obtained mass difference allowed an easy identification of the cysteine containing peptides. With these experiments, it was successfully demonstrated that the developed method can serve as a tool for counting cysteine moieties in proteins and, thus, be used as an additional technique in protein identification experiments.

  5. Quinone-induced protein handling changes: Implications for major protein handling systems in quinone-mediated toxicity

    SciTech Connect

    Xiong, Rui; Siegel, David; Ross, David

    2014-10-15

    Para-quinones such as 1,4-Benzoquinone (BQ) and menadione (MD) and ortho-quinones including the oxidation products of catecholamines, are derived from xenobiotics as well as endogenous molecules. The effects of quinones on major protein handling systems in cells; the 20/26S proteasome, the ER stress response, autophagy, chaperone proteins and aggresome formation, have not been investigated in a systematic manner. Both BQ and aminochrome (AC) inhibited proteasomal activity and activated the ER stress response and autophagy in rat dopaminergic N27 cells. AC also induced aggresome formation while MD had little effect on any protein handling systems in N27 cells. The effect of NQO1 on quinone induced protein handling changes and toxicity was examined using N27 cells stably transfected with NQO1 to generate an isogenic NQO1-overexpressing line. NQO1 protected against BQ–induced apoptosis but led to a potentiation of AC- and MD-induced apoptosis. Modulation of quinone-induced apoptosis in N27 and NQO1-overexpressing cells correlated only with changes in the ER stress response and not with changes in other protein handling systems. These data suggested that NQO1 modulated the ER stress response to potentiate toxicity of AC and MD, but protected against BQ toxicity. We further demonstrated that NQO1 mediated reduction to unstable hydroquinones and subsequent redox cycling was important for the activation of the ER stress response and toxicity for both AC and MD. In summary, our data demonstrate that quinone-specific changes in protein handling are evident in N27 cells and the induction of the ER stress response is associated with quinone-mediated toxicity. - Highlights: • Unstable hydroquinones contributed to quinone-induced ER stress and toxicity.

  6. Electron paramagnetic resonance study of the generation of reactive oxygen species catalysed by transition metals and quinoid redox cycling by inhalable ambient particulate matter.

    PubMed

    Valavanidis, A; Fiotakis, K; Bakeas, E; Vlahogianni, T

    2005-01-01

    production of superoxide anion and the damaging hydroxyl radical in aqueous and in DMSO suspensions of PM without H2O2. From these results, it is suggested that the cytotoxic and carcinogenic potential of PM can be partly the result of redox cycling of persistent quinoid radicals, which generate large amounts of ROS. In the second phase, the water-soluble fraction of PM elicits DNA damage via reactive transition metal-dependent formation of hydroxyl radicals, implicating an important role for hydrogen peroxide. Together, these data indicate the importance of mechanisms involving redox cycling of quinones and Fenton-type reactions by transition metals in the generation of ROS. These results are supported by recent studies indicating cytotoxic effects, especially mitochondrial damage, by PM extracts and differential mechanisms of cell killing by redox cycling quinones.

  7. Substituted quinoline quinones as surrogates for the PQQ cofactor: an electrochemical and computational study.

    PubMed

    Dorfner, Walter L; Carroll, Patrick J; Schelter, Eric J

    2015-04-17

    Pyrroloquinoline quinones (PQQ) are important cofactors that shuttle redox equivalents in diverse metalloproteins. Quinoline 7,8-quinones have been synthesized and characterized as surrogates for PQQ to elucidate redox energetics within metalloenzyme active sites. The quinoline 7,8-quinones were accessed using polymer-supported iodoxybenzoic acid and the compounds evaluated using solution electrochemistry. Together with a family of quinones, the products were evaluated computationally and used to generate a predictive correlation between a computed ΔG and the experimental reduction potentials.

  8. Activation of Electron-Deficient Quinones through Hydrogen-Bond-Donor-Coupled Electron Transfer.

    PubMed

    Turek, Amanda K; Hardee, David J; Ullman, Andrew M; Nocera, Daniel G; Jacobsen, Eric N

    2016-01-11

    Quinones are important organic oxidants in a variety of synthetic and biological contexts, and they are susceptible to activation towards electron transfer through hydrogen bonding. Whereas this effect of hydrogen bond donors (HBDs) has been observed for Lewis basic, weakly oxidizing quinones, comparable activation is not readily achieved when more reactive and synthetically useful electron-deficient quinones are used. We have successfully employed HBD-coupled electron transfer as a strategy to activate electron-deficient quinones. A systematic investigation of HBDs has led to the discovery that certain dicationic HBDs have an exceptionally large effect on the rate and thermodynamics of electron transfer. We further demonstrate that these HBDs can be used as catalysts in a quinone-mediated model synthetic transformation. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Activity of quinone alkylating agents in quinone-resistant cells.

    PubMed

    Begleiter, A; Leith, M K

    1990-05-15

    The role of the quinone group in the antitumor activity of quinone alkylating agents, such as mitomycin C and 2,5-diaziridinyl-3,5-bis(carboethoxyamino)-1,4-benzoquinone, is still uncertain. The quinone group may contribute to antitumor activity by inducing DNA strand breaks through the formation of free radicals and/or by influencing the alkylating activity of the quinone alkylators. The cytotoxic activity and DNA damage produced by the model quinone alkylating agents, benzoquinone mustard and benzoquinone dimustard, were compared in L5178Y murine lymphoblasts sensitive and resistant to the model quinone antitumor agent, hydrolyzed benzoquinone mustard. The resistant cell lines, L5178Y/HBM2 and L5178Y/HBM10, have increased concentrations of glutathione and elevated catalase, superoxide dismutase, glutathione S-transferase, and DT-diaphorase activity. L5178Y/HBM2 and L5178Y/HBM10 cells were 7.4- and 8.5-fold less sensitive to benzoquinone mustard and 1.7- and 4.3-fold less sensitive to benzoquinone dimustard, respectively, compared with sensitive cells, but showed no resistance to the non-quinone alkylating agent, aniline mustard. The formation of DNA double strand breaks by benzoquinone mustard was reduced by 2- and 8-fold in L5178Y/HBM2 and L5178Y/HBM10 cells, respectively, while double strand break formation by benzoquinone dimustard was reduced only in the L5178Y/HBM10 cells. The number of DNA-DNA cross-links produced by benzoquinone mustard was 3- and 6-fold lower, and the number produced by benzoquinone dimustard was 35% and 2-fold lower in L5178Y/HBM2 and L5178Y/HBM10 cells, respectively, compared with L5178Y parental cells. In contrast, cross-linking by aniline mustard was unchanged in sensitive and resistant cells. Dicoumarol, an inhibitor of DT-diaphorase, increased the cytotoxic activity of both benzoquinone mustard and benzoquinone dimustard in L5178Y/HBM10 cells. This study provides evidence that elevated DT-diaphorase activity in the resistant cells

  10. Two-electron reduction of quinones by Enterobacter cloacae PB2 pentaerythritol tetranitrate reductase: quantitative structure-activity relationships.

    PubMed

    Miseviciene, Lina; Anusevicius, Zilvinas; Sarlauskas, Jonas; Harris, Richard J; Scrutton, Nigel S; Cenas, Narimantas

    2007-01-01

    In order to clarify the poorly understood mechanisms of two-electron reduction of quinones by flavoenzymes, we examined the quinone reductase reactions of a member of a structurally distinct old yellow enzyme family, Enterobacter cloacae PB2 pentaerythritol tetranitrate reductase (PETNR). PETNR catalyzes two-electron reduction of quinones according to a 'ping-pong' scheme. A multiparameter analysis shows that the reactivity of quinones increases with an increase in their single-electron reduction potential and pK(a) of their semiquinones (a three-step (e(-),H(+),e(-)) hydride transfer scheme), or with an increase in their hydride-transfer potential (E(7)(H(-))) (a single-step (H(-)) hydride transfer scheme), and decreases with a decrease in their van der Waals volume. However, the pH-dependence of PETNR reactivity is more consistent with a single-step hydride transfer. A comparison of X-ray data of PETNR, mammalian NAD(P)H : quinone oxidoreductase (NQO1), and Enterobacter cloacae nitroreductase, which reduce quinones in a two-electron way, and their reactivity revealed that PETNR is much less reactive, and much less sensitive to the quinone substrate steric effects than NQO1. This may be attributed to the lack of pi-pi stacking between quinone and the displaced aromatic amino acid in the active center, e.g., with Phe-178' in NQO1.

  11. Method for generating a highly reactive plasma for exhaust gas after treatment and enhanced catalyst reactivity

    SciTech Connect

    Whealton, John H.; Hanson, Gregory R.; Storey, John M.; Raridon, Richard J.; Armfield, Jeffrey S.; Bigelow, Timothy S.; Graves, Ronald L.

    2000-07-01

    This patent application describes a method and apparatus of exhaust gas remediation that enhance the reactivity of the material catalysts found within catalytic converters of cars, trucks, and power stations.

  12. Synthetic Strategies to Terpene Quinones/Hydroquinones

    PubMed Central

    Gordaliza, Marina

    2012-01-01

    The cytotoxic and antiproliferative properties of many natural sesquiterpene-quinones and -hydroquinones from sponges offer promising opportunities for the development of new drugs. A review dealing with different strategies for obtaining bioactive terpenyl quinones/hydroquinones is presented. The different synthetic approches for the preparation of the most relevant quinones/hydroquinones are described. PMID:22412807

  13. Identification of quinone imine containing glutathione conjugates of diclofenac in rat bile.

    PubMed

    Waldon, Daniel J; Teffera, Yohannes; Colletti, Adria E; Liu, Jingzhou; Zurcher, Danielle; Copeland, Katrina W; Zhao, Zhiyang

    2010-12-20

    High-resolution accurate MS with an LTQ-Orbitrap was used to identify quinone imine metabolites derived from the 5-hydroxy (5-OH) and 4 prime-hydroxy (4'-OH) glutathione conjugates of diclofenac in rat bile. The initial quinone imine metabolites formed by oxidation of diclofenac have been postulated to be reactive intermediates potentially involved in diclofenac-mediated hepatotoxicity; while these metabolites could be formed using in vitro systems, they have never been detected in vivo. This report describes the identification of secondary quinone imine metabolites derived from 5-OH and 4'-OH diclofenac glutathione conjugates in rat bile. To verify the proposed structures, the diclofenac quinone imine GSH conjugate standards were prepared synthetically and enzymatically. The novel metabolite peaks displayed the identical retention times, accurate mass MS/MS spectra, and the fragmentation patterns as the corresponding authentic standards. The formation of these secondary quinone metabolites occurs only under conditions where bile salt homeostasis was experimentally altered. Standard practice in biliary excretion experiments using bile duct-cannulated rats includes infusion of taurocholic acid and/or other bile acids to replace those lost due to continuous collection of bile; for this experiment, the rats received no replacement bile acid infusion. High-resolution accurate mass spectrometry data and comparison with chemically and enzymatically prepared quinone imines of diclofenac glutathione conjugates support the identification of these metabolites. A mechanism for the formation of these reactive quinone imine containing glutathione conjugates of diclofenac is proposed.

  14. Interaction of chlorinated phenolics and quinones with the mitochondrial respiration: a comparison of the o- and p-chlorinated quinones and hydroquinones

    SciTech Connect

    Pritsos, C.A.; Pointon, M.; Pardini, R.S.

    1987-05-01

    Interest in the environmental toxicology of chlorinated catechols and their analogous quinones was prompted by their acute toxicity towards fish and other aquatic organisms. Chlorophenols, such as pentachlorophenol, as well as tetrachlorocatechol have been suggested to uncouple mitochondrial oxidative phosphorylation while chloranil and tetrachloro-o-benzoquinone have been shown to inhibit liver mitochondrial respiration, which may be related to their cytotoxicity. Another chlorinated quinone fungicide, 2,3 dichloro-1,4-naphthoquinone (CNQ) has been studied and shown to both uncouple oxidative phosphorylation and inhibit respiration in liver and heart mitochondria. CNQ was shown to undergo redox cycling with mitochondria, with a concomitant production of toxic oxygen species including superoxide and hydrogen peroxide. These reactive oxygen species were associated with the generation of mitochondrial oxidative stress, and were related to the toxic action of CNQ. Based upon these previous findings, the authors examined the interaction of both the ortho and para isomers of tetrachloro-benzoquinone and their corresponding hydroquinones with mitochondria in order to prove their mechanism of actions and compare the reactions of the various isomers.

  15. Multicomponent Condensation Reactions via ortho-Quinone Methides.

    PubMed

    Allen, Emily E; Zhu, Calvin; Panek, James S; Schaus, Scott E

    2017-03-30

    Iron(III) salts promote the condensation of aldehydes or acetals with electron-rich phenols to generate ortho-quinone methides that undergo Diels-Alder condensations with alkenes. The reaction sequence occurs in a single vessel to afford benzopyrans in up to 95% yield. The reaction was discovered while investigating a two-component strategy using 2-(hydroxy(phenyl)methyl)phenols to access the desired ortho-quinone methide in a Diels-Alder condensation. The two-component condensation also afforded the corresponding benzopyran products in yields up to 97%. Taken together, the two- and three-component strategies using ortho-quinone methide intermediates provide efficient access to benzopyrans in good yields and selectivities.

  16. Quantitative assessment of reactive oxygen species generation by cavitation incepted efficiently using nonlinear propagation effect

    NASA Astrophysics Data System (ADS)

    Yasuda, Jun; Yoshizawa, Shin; Umemura, Shin-ichiro

    2015-10-01

    Sonodynamic treatment is a treatment method that uses chemical bio-effect of cavitation bubbles. Reactive oxygen species that can kill cancerous tissue is induced by such chemical effect of cavitation bubbles and it is important to generate them efficiently for effective sonodynamic treatment. Cavitation cloud can be formed by an effect of nonlinear propagation and focus and in this study, it was experimentally investigated if cavitation cloud was useful for efficient generation of reactive oxygen species. As a result, it was demonstrated that cavitation cloud would be useful for efficient generation of reactive oxygen species.

  17. Generation of reactive species by an atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Kelly, S.; Turner, M. M.

    2014-12-01

    The role of gas mixing in reactive species delivery to treatment surfaces for an atmospheric pressure capacitively coupled plasma helium jet is investigated by numerical modelling. Atomic oxygen in the jet effluent is shown to quickly convert to ozone for increasing device to surface separation due to the molecular oxygen present in the gas mixture. Surface profiles of reactive oxygen species show narrow peaks for atomic oxygen and broader surface distributions for ozone and metastable species. Production efficiency of atomic oxygen to the helium plasma jet by molecular oxygen admixture is shown to be dependent on electro-negativity. Excessive molecular oxygen admixture results in negative ion dominance over electrons which eventually quenches the plasma. Interaction of the plasma jet with an aqueous surface showed hydrogen peroxide as the dominant species at this interface. Gas heating by the plasma is found to be dominated by elastic electron collisions and positive ion heating. Comparison with experimental measurements for atomic oxygen shows good agreement.

  18. Quinone formation as a chemoprevention strategy for hybrid drugs: balancing cytotoxicity and cytoprotection.

    PubMed

    Dunlap, Tareisha; Chandrasena, R Esala P; Wang, Zhiqiang; Sinha, Vaishali; Wang, Zhican; Thatcher, Gregory R J

    2007-12-01

    Cellular defense mechanisms that respond to damage from oxidative and electrophilic stress, such as from quinones, represent a target for chemopreventive agents. Drugs bioactivated to quinones have the potential to activate antioxidant/electrophile responsive element (ARE) transcription of genes for cytoprotective phase 2 enzymes such as NAD(P)H-dependent quinone oxidoreductase (NQO1) but can also cause cellular damage. Two isomeric families of compounds were prepared, including the NO-NSAIDs (NO-donating nonsteroidal anti-inflammatory drugs) NCX 4040 and NCX 4016; one family was postulated to release a quinone methide on esterase bioactivation. The study of reactivity and GSH conjugation in model and cell systems confirmed the postulate. The quinone-forming family, including NCX 4040 and conisogenic bromides and mesylate, was rapidly bioactivated to a quinone, which gave activation of ARE and consequent induction of NQO1 in liver cells. Although the control family, including NCX 4016 and conisogenic bromides and mesylates, cannot form a quinone, ARE activation and NQO1 induction were observed, compatible with slower SN2 reactions with thiol sensor proteins, and consequent ARE-luciferase and NQO1 induction. Using a Chemoprevention Index estimate, the quinone-forming compounds suffered because of high cytoxicity and were more compatible with cancer therapy than chemoprevention. In the Comet assay, NCX 4040 was highly genotoxic relative to NCX 4016. There was no evidence that NO contributes to the observed biological activity and no evidence that NCX 4040 is an NO donor, instead, rapidly releasing NO3- and quinone. These results indicate a strategy for studying the quinone biological activity and reinforce the therapeutic attributes of NO-ASA through structural elements other than NO and ASA.

  19. Ultrasensitive determination of pyrroloquinoline quinone in human plasma by HPLC with chemiluminescence detection using the redox cycle of quinone.

    PubMed

    Fukuda, Mizuho; El-Maghrabey, Mahmoud H; Kishikawa, Naoya; Ikemoto, Kazuto; Kuroda, Naotaka

    2017-10-25

    A fast, accurate, and ultrasensitive high-performance liquid chromatography method with chemiluminescence detection (HPLC-CL) was optimized and validated for the determination of pyrroloquinoline quinone (PQQ) concentration in human plasma following solid-phase extraction (SPE). This method is based on the redox cycle of the reaction between PQQ and dithiothreitol, which generates reactive oxygen species that can be detected using luminol as a CL probe. The isocratic HPLC system comprised an ODS column and 4.0mM tetra-n-butylammonium bromide in Tris-HNO3 buffer (pH 8.8; 50mM)-acetonitrile (7:3, v/v) as mobile phase. A novel, rapid, and simple SPE method was also developed providing excellent %recovery (≥95.2%) for PQQ from human plasma samples. The proposed method was linear over the range of 4.0-400nmol/L plasma of PQQ with a lower detection limit (S/N=3) of 1.08 nmol/L plasma (0.27nM). The method was successfully implemented to determine PQQ concentration in the plasma of healthy individuals after administration of PQQ supplements. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. The quinones of benzocyclobutadiene: a computational study.

    PubMed

    Golas, Ewa; Lewars, Errol; Liebman, Joel F

    2009-08-27

    The conventional (excluding non-Kekulé, singlet diradical structures) quinones of benzocyclobutadiene were studied computationally. Eight structures were examined, namely (based on the CA names for benzocyclobutenedione), benzocyclobutenedione or bicyclo[4.2.0]octa-1,3,5-triene-7,8-dione, bicyclo[4.2.0]octa-3,5,8-triene-2,7-dione, bicyclo[4.2.0]octa-1,4,6-triene-3,8-dione, bicyclo[4.2.0]octa-1(6),4,7-triene-2,3-dione, bicyclo[4.2.0]octa-1(8), 4,6-triene-2,3-dione, bicyclo[4.2.0]octa-1(6),3,7-triene-2,5-dione, bicyclo[4.2.0]octa-1(8),3,6-triene-2,5-dione, and bicyclo[4.2.0]octa-1,5,7-triene-3,4-dione (the question of resonance or tautomerism for the 2,3-dione pair and the 2,5-dione pair is considered). Using DFT (B3LYP/6-31G*) and ab initio (MP2/6-31G*) methods the geometries of the eight species were optimized, giving similar results for the two methods. The heats of formation of the quinones were calculated, placing them in low-energy (-17 kJ mol(-1), 7,8-dione), medium-energy (79-137 kJ mol(-1), 2,7-, 3,8-, and 3,4-diones), and high-energy (260-275 kJ mol(-1), 2,3- and 2,5-diones) groups. Diels-Alder reactivity as dienophiles with butadiene indicated the 2,7-, 3,8-, and particularly the 3,4-quinone may be relatively unreactive toward dimerization or polymerization and are attractive synthesis goals. Isodesmic ring-opening reactions and NICS calculations showed aromatic/nonaromatic properties to be essentially as expected from the presence of a benzene or cyclobutadiene ring. UV spectra, ionization energy electron affinity, and HOMO/LUMO energies were also calculated.

  1. Development of an Enhanced GenVARR™ (Generator Volt Ampere Reactive Reserve) System

    SciTech Connect

    Schatz, Joe E.

    2009-03-12

    Transmission system operators require near real time knowledge of reactive power capability to reliably operate large electric power transmission systems. Reactive power produced by, or capable of being produced by, a power generator is often estimated based on a series of mega volt amperes (MVA) capability curves for the generator. These curves indicate the ability of the generator to produce real and reactive power under a variety of conditions. In transmission planning and operating studies, it is often assumed, based on estimates for these capability curves, that the generator can provide its rated MVA capability output when needed for system stability However, generators may not always operate at levels depicted by the maximum MVA capability curve due to present constraints. Transmission system operators utilizing the generators’ capability curves for operation decisions regarding transmission system stability or for planning horizons may overestimate the capability of the generators to supply reactive power when required. Southern Company has enhanced GenVARR(TM), the system of plant data query, retrieval, and analysis and calculates the actual – not estimated -- remaining reactive power output capability. The remaining reactive output is considered spinning reserve and is displayed graphically to transmission control center and generating plant operators to identify real time VAR limits. GenVARR is capable of aggregating generators from a defined region, or other user selectable combinations, to represent the available reserves that the operators are specifically interested in. GenVARR(TM) has been put into live production operation and is expected to significantly improve the overall visibility of the reactive reserve capability of the system. This new version of GenVARR(TM) significantly enhances the products structure and performance, and enables links to other key transmission system operation tools.

  2. Quinone- and nitroreductase reactions of Thermotoga maritima peroxiredoxin-nitroreductase hybrid enzyme.

    PubMed

    Anusevičius, Žilvinas; Misevičienė, Lina; Šarlauskas, Jonas; Rouhier, Nicolas; Jacquot, Jean-Pierre; Čėnas, Narimantas

    2012-12-01

    Thermotoga maritima peroxiredoxin-nitroreductase hybrid enzyme (Prx-NR) consists of a FMN-containing nitroreductase (NR) domain fused to a peroxiredoxin (Prx) domain. These domains seem to function independently as no electron transfer occurs between them. The reduction of quinones and nitroaromatics by NR proceeded in a two-electron manner, and follows a 'ping-pong' scheme with sometimes pronounced inhibition by quinone substrate. The comparison of steady- and presteady-state kinetic data shows that in most cases, the oxidative half-reaction may be rate-limiting in the catalytic cycle of NR. The enzyme was inhibited by dicumarol, a classical inhibitor of oxygen-insensitive nitroreductases. The reduction of quinones and nitroaromatic compounds by Prx-NR was characterized by the linear dependence of their reactivity (logk(cat)/K(m)) on their single-electron reduction potentials E(7)(1), while the reactivity of quinones markedly exceeded the one with nitroaromatics. It shows that NR lacks the specificity for the particular structure of these oxidants, except their single-electron accepting potency and the rate of electron self-exchange. It points to the possibility of a single-electron transfer step in a net two-electron reduction of quinones and nitroaromatics by T. maritima Prx-NR, and to a significant diversity of the structures of flavoenzymes which may perform the two-electron reduction of quinones and nitroaromatics.

  3. Method for generating a highly reactive plasma for exhaust gas aftertreatment and enhanced catalyst reactivity

    DOEpatents

    Whealton, John H.; Hanson, Gregory R.; Storey, John M.; Raridon, Richard J.; Armfield, Jeffrey S.; Bigelow, Timothy S.; Graves, Ronald L.

    2001-01-01

    A method for non-thermal plasma aftertreatment of exhaust gases the method comprising the steps of providing short risetime (about 40 ps), high frequency (about 5G hz), high power bursts of low-duty factor microwaves sufficient to generate a dielectric barrier discharge and passing a gas to treated through the discharge so as to cause dissociative reduction of the exhaust gases. The invention also includes a reactor for generating the non-thermal plasma.

  4. 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.

  5. Removal of bisphenol derivatives through quinone oxidation by polyphenol oxidase and subsequent quinone adsorption on chitosan in the heterogeneous system.

    PubMed

    Kimura, Yuji; Takahashi, Ayumi; Kashiwada, Ayumi; Yamada, Kazunori

    2015-01-01

    In this study, the combined use of a biopolymer chitosan and an oxidoreductase polyphenol oxidase (PPO) was systematically investigated for the removal of bisphenol derivatives from aqueous medium. The process parameters, such as the pH value, temperature, and PPO concentration, were estimated to conduct the enzymatic quinone oxidation of bisphenol derivatives by as little enzyme as possible. Bisphenol derivatives effectively underwent PPO-catalysed quinone oxidation without H2O2 unlike other oxidoreductases, such as peroxidase and tyrosinase, and the optimum conditions were determined to be pH 7.0 and 40°C for bisphenol B, bisphenol E, bisphenol O, and bisphenol Z; pH 7.0 and 30°C for bisphenol C and bisphenol F; and pH 8.0 and 40°C for bisphenol T. They were completely removed through adsorption of enzymatically generated quinone derivatives on chitosan beads or chitosan powders. Quinone adsorption on chitosan beads or chitosan powders in the heterogeneous system was found to be a more effective procedure than generation of aggregates in the homogeneous system with chitosan solution. The removal time was shortened by increasing the amount of chitosan beads or decreasing the size of the chitosan powders.

  6. Water-soluble fullerene materials for bioapplications: photoinduced reactive oxygen species generation

    USDA-ARS?s Scientific Manuscript database

    The photoinduced reactive oxygen species (ROS) generation from several water-soluble fullerenes was examined. Macromolecular or small molecular water-soluble fullerene complexes/derivatives were prepared and their 1O2 and O2•- generation abilities were evaluated by EPR spin-trapping methods. As a r...

  7. Benzofuran-, benzothiophene-, indazole- and benzisoxazole- quinones: excellent substrates for NAD(P)H:quinone oxidoreductase 1

    PubMed Central

    Newsome, Jeffery J.; Hassani, Mary; Swann, Elizabeth; Bibby, Jane M.; Beall, Howard D.; Moody, Christopher J.

    2013-01-01

    A series of heterocyclic quinones based on benzofuran, benzothiophene, indazole and benzisoxazole has been synthesized, and evaluated for their ability to function as substrates for recombinant human NAD(P)H:quinone oxidoreductase (NQO1), a two-electron reductase upregulated in tumor cells. Overall, the quinones are excellent substrates for NQO1, approaching the reduction rates observed for menadione PMID:23635904

  8. Free radical-derived quinone methide mediates skin tumor promotion by butylated hydroxytoluene hydroperoxide: expanded role for electrophiles in multistage carcinogenesis.

    PubMed Central

    Guyton, K Z; Bhan, P; Kuppusamy, P; Zweier, J L; Trush, M A; Kensler, T W

    1991-01-01

    Free radical derivatives of peroxides, hydroperoxides, and anthrones are thought to mediate tumor promotion by these compounds. Further, the promoting activity of phorbol esters is attributed, in part, to their ability to stimulate the cellular generation of oxygen radicals. A hydroperoxide metabolite of butylated hydroxytoluene, 2,6-di-tert-butyl-4-hydroperoxyl-4-methyl-2,5-cyclohexadienone (BHTOOH), has previously been shown to be a tumor promoter in mouse skin. BHTOOH is extensively metabolized by murine keratinocytes to several radical species. The primary radical generated from BHTOOH is a phenoxyl radical that can disproportionate to form butylated hydroxytoluene quinone methide, a reactive electrophile. Since electrophilic species have not been previously postulated to mediate tumor promotion, the present study was undertaken to examine the role of this electrophile in the promoting activity of BHTOOH. The biological activities of two chemical analogs of BHTOOH, 4-trideuteromethyl-BHTOOH and 4-tert-butyl-BHTOOH, were compared with that of the parent compound. 4-Trideuteromethyl-BHTOOH and 4-tert-butyl-BHTOOH have a reduced ability or inability, respectively, to form a quinone methide; however, like the parent compound, they both generate a phenoxyl radical when incubated with keratinocyte cytosol. The potency of BHTOOH, 4-trideuteromethyl-BHTOOH, and 4-tert-butyl-BHTOOH as inducers of ornithine decarboxylase, a marker of tumor promotion, was commensurate with their capacity for generating butylated hydroxytoluene quinone methide. These initial results were confirmed in a two-stage tumor promotion protocol in female SENCAR mice. Together, these data indicate that a quinone methide is mediating tumor promotion by BHTOOH, providing direct evidence that an electrophilic intermediate can elicit this stage of carcinogenesis. PMID:1846971

  9. Reactivity of waste generated during lead recycling: an integrated study.

    PubMed

    Lassin, Arnault; Piantone, Patrice; Burnol, André; Bodénan, Françoise; Chateau, Laurent; Lerouge, Catherine; Crouzet, Catherine; Guyonnet, Dominique; Bailly, Laurent

    2007-01-31

    Lead consumption in Europe is 2.054 M tonnes/year, more than 70% of which is produced by recycling and, more specifically, the recycling of car batteries. This industry is jeopardised by the method employed so far, recycling by alkaline fusion, because the treatment produces 200,000 tonnes of toxic and unstable slag. The study presented here attempts to clarify the approach and the combined tools employed (mineralogy, chemistry, leaching, thermodynamics), to construct a coherent physicochemical model of slag behaviour. The model was then used to carry out sensitivity analyses with various landfill scenarios, and to propose adjustments to the process to recover the residual heavy metals and to upgrade as secondary raw products the co-products generated by the inerting of the slag.

  10. A flexible active and reactive power control strategy for a variable speed constant frequency generating system

    SciTech Connect

    Tang, Y.; Xu, L.

    1995-07-01

    Variable-speed constant-frequency generating systems are used in wind power, hydro power, aerospace, and naval power generations to enhance efficiency and reduce friction. In these applications, an attractive candidate is the slip power recovery system comprising of doubly excited induction machine or doubly excited brushless reluctance machine and PWM converters with a dc link. In this paper, a flexible active and reactive power control strategy is developed, such that the optimal torque-speed profile of the turbine can be followed and overall reactive power can be controlled, while the machine copper losses have been minimized. At the same time, harmonics injected into the power network has also been minimized. In this manner, the system can function as both a high-efficient power generator and a flexible reactive power compensator.

  11. Enzymatic treatment of sulfonated aromatic amines generated from reductive degradation of reactive azo dyes.

    PubMed

    Biswas, Mousumi Mani; Taylor, Keith E; Bewtra, Jatinder K; Biswas, Nihar

    2007-04-01

    Anaerobic degradation, an effective treatment process of textile industry effluent, generates sulfonated aromatic amines, which are carcinogenic, mutagenic, and resistant to microbial degradation. These aromatic amines can be effectively removed by oxidative polymerization catalyzed by peroxidase enzyme. The amines, generated in this study from the anaerobic reduction by zero-valent iron of two reactive azo dyes (Reactive Red 2 [RR2] and Reactive Black 5 [RB5]), were successfully removed (90%) by Arthromyces ramosus peroxidase (ARP). For better understanding of the process, enzymatic treatment of two model compounds, diphenylamine (DPA) and 2-amino-8-naphthol-3,6-disulfonic acid (ANDSA), were also studied. Diphenylamine has a similar diarylamine bond as RR2. The ANDSA has a similar structure as the dye reduction products. The secondary amine bond in DPA and RR2 were oxidized by ARP. Enzymatic reaction of sulfonated aromatic amines generated soluble colored compounds, which were removed by coagulant. Optimum reaction parameters were also determined.

  12. Sites of reactive oxygen species generation by mitochondria oxidizing different substrates☆

    PubMed Central

    Quinlan, Casey L.; Perevoshchikova, Irina V.; Hey-Mogensen, Martin; Orr, Adam L.; Brand, Martin D.

    2013-01-01

    Mitochondrial radical production is important in redox signaling, aging and disease, but the relative contributions of different production sites are poorly understood. We analyzed the rates of superoxide/H2O2 production from different defined sites in rat skeletal muscle mitochondria oxidizing a variety of conventional substrates in the absence of added inhibitors: succinate; glycerol 3-phosphate; palmitoylcarnitine plus carnitine; or glutamate plus malate. In all cases, the sum of the estimated rates accounted fully for the measured overall rates. There were two striking results. First, the overall rates differed by an order of magnitude between substrates. Second, the relative contribution of each site was very different with different substrates. During succinate oxidation, most of the superoxide production was from the site of quinone reduction in complex I (site IQ), with small contributions from the flavin site in complex I (site IF) and the quinol oxidation site in complex III (site IIIQo). However, with glutamate plus malate as substrate, site IQ made little or no contribution, and production was shared between site IF, site IIIQo and 2-oxoglutarate dehydrogenase. With palmitoylcarnitine as substrate, the flavin site in complex II (site IIF) was a major contributor (together with sites IF and IIIQo), and with glycerol 3-phosphate as substrate, five different sites all contributed, including glycerol 3-phosphate dehydrogenase. Thus, the relative and absolute contributions of specific sites to the production of reactive oxygen species in isolated mitochondria depend very strongly on the substrates being oxidized, and the same is likely true in cells and in vivo. PMID:24024165

  13. Quinone project. Progress report. [Poly(acene quinone)

    SciTech Connect

    Rickert, S.E.

    1986-01-10

    This report is divided into sections appropriate for the four publications which were or will soon be published from this research. Additional references and information can be obtained from these papers. The basic premise behind this work has been, and continues to be, the preparation of stable electronic polymeric conductors, which have reversible, high capacity, oxidation-reduction characteristics. The heavy synthetic component to the initial papers is unavoidable, as new ground needed to be broken in synthetic methods for all compounds studied. Unfortunately, previous investigators had not done a thorough job of studying the complexities of these 'simple' reactions. In the next year, high quality, high capacity films and fibers of both PBHQ and poly(acene quinones) should be produced. 4 refs.

  14. Crystal Structure and Density Functional Theory Studies of Toxic Quinone Metabolites of Polychlorinated Biphenyls

    PubMed Central

    Song, Yang; Ambati, Jyothirmai; Parkin, Sean; Rankin, Stephen E.; Robertson, Larry W.; Lehmler, Hans-Joachim

    2011-01-01

    Lower chlorinated polychlorinated biphenyls (PCBs) are readily metabolized via hydroxylated metabolites to reactive PCB quinones. Although these PCB metabolites elicit biochemical changes by mechanisms involving cellular target molecules, such as the Aryl hydrocarbon receptor, and toxicity by interacting with enzymes like topoisomerases, only few PCB quinones have been synthesized and their conformational properties investigated. Similar to the parent compounds, knowledge of the three-dimensional structure of PCB quinones may therefore be important to assess their fate and risk. To address this gap in our knowledge, the gas phase molecular structure of a series of PCB quinones was predicted using HF/3-21G, B3LYP/6-31G** and UB3LYP/6-311G** calculations and compared to the respective solid state structure. All three methods overestimated the Cl-C bond length, but otherwise provided a reasonable approximation of the solid state bond angles and bond lengths. Overall, the UB3LYP/6-311G** level of theory yielded the best approximation of the molecular structure of PCB quinones in the solid state. Chlorine addition at the ortho position of both rings was found to increase the dihedral angle of the resulting quinone compound, which may have important implications for their interaction with cellular targets and, thus, their toxicity. PMID:21824639

  15. The Role of External and Matrix pH in Mitochondrial Reactive Oxygen Species Generation*

    PubMed Central

    Selivanov, Vitaly A.; Zeak, Jennifer A.; Roca, Josep; Cascante, Marta; Trucco, Massimo; Votyakova, Tatyana V.

    2008-01-01

    Reactive oxygen species (ROS) generation in mitochondria as a side product of electron and proton transport through the inner membrane is important for normal cell operation as well as development of pathology. Matrix and cytosol alkalization stabilizes semiquinone radical, a potential superoxide producer, and we hypothesized that proton deficiency under the excess of electron donors enhances reactive oxygen species generation. We tested this hypothesis by measuring pH dependence of reactive oxygen species released by mitochondria. The experiments were performed in the media with pH varying from 6 to 8 in the presence of complex II substrate succinate or under more physiological conditions with complex I substrates glutamate and malate. Matrix pH was manipulated by inorganic phosphate, nigericine, and low concentrations of uncoupler or valinomycin. We found that high pH strongly increased the rate of free radical generation in all of the conditions studied, even when ΔpH = 0 in the presence of nigericin. In the absence of inorganic phosphate, when the matrix was the most alkaline, pH shift in the medium above 7 induced permeability transition accompanied by the decrease of ROS production. ROS production increase induced by the alkalization of medium was observed with intact respiring mitochondria as well as in the presence of complex I inhibitor rotenone, which enhanced reactive oxygen species release. The phenomena revealed in this report are important for understanding mechanisms governing mitochondrial production of reactive oxygen species, in particular that related with uncoupling proteins. PMID:18687689

  16. The role of external and matrix pH in mitochondrial reactive oxygen species generation.

    PubMed

    Selivanov, Vitaly A; Zeak, Jennifer A; Roca, Josep; Cascante, Marta; Trucco, Massimo; Votyakova, Tatyana V

    2008-10-24

    Reactive oxygen species (ROS) generation in mitochondria as a side product of electron and proton transport through the inner membrane is important for normal cell operation as well as development of pathology. Matrix and cytosol alkalization stabilizes semiquinone radical, a potential superoxide producer, and we hypothesized that proton deficiency under the excess of electron donors enhances reactive oxygen species generation. We tested this hypothesis by measuring pH dependence of reactive oxygen species released by mitochondria. The experiments were performed in the media with pH varying from 6 to 8 in the presence of complex II substrate succinate or under more physiological conditions with complex I substrates glutamate and malate. Matrix pH was manipulated by inorganic phosphate, nigericine, and low concentrations of uncoupler or valinomycin. We found that high pH strongly increased the rate of free radical generation in all of the conditions studied, even when DeltapH=0 in the presence of nigericin. In the absence of inorganic phosphate, when the matrix was the most alkaline, pH shift in the medium above 7 induced permeability transition accompanied by the decrease of ROS production. ROS production increase induced by the alkalization of medium was observed with intact respiring mitochondria as well as in the presence of complex I inhibitor rotenone, which enhanced reactive oxygen species release. The phenomena revealed in this report are important for understanding mechanisms governing mitochondrial production of reactive oxygen species, in particular that related with uncoupling proteins.

  17. Selective synthesis of the para-quinone region of geldanamycin.

    PubMed

    Andrus, Merritt B; Hicken, Erik J; Meredith, Erik L; Simmons, Bryon L; Cannon, John F

    2003-10-16

    [structure: see text] The quinone portion of the ansamycin geldanamycin was made with complete selectivity from the 1,4-dihydroquinone generated from a 1,4-bis-methoxymethyl (MOM) ether intermediate. Palladium catalysis with air gave the desired product in 98% isolated yield. The structure was established using NMR, UV, and X-ray analysis with comparisons to geldanamycin, ortho-quino-geldanamycin and a model compound.

  18. 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...

  19. 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...

  20. EXAMINATION OF QUINONE TOXICITY USING YEAST SACCHAROMYCES CEREVISIAE MODEL SYSTEM. (R827352C007)

    EPA Science Inventory

    The toxicity of quinones is generally thought to occur by two mechanisms: the formation of covalent bonds with biological molecules by Michael addition chemistry and the catalytic reduction of oxygen to superoxide and other reactive oxygen species (ROS) (redox cycling). In an ...

  1. EXAMINATION OF QUINONE TOXICITY USING YEAST SACCHAROMYCES CEREVISIAE MODEL SYSTEM. (R827352C007)

    EPA Science Inventory

    The toxicity of quinones is generally thought to occur by two mechanisms: the formation of covalent bonds with biological molecules by Michael addition chemistry and the catalytic reduction of oxygen to superoxide and other reactive oxygen species (ROS) (redox cycling). In an ...

  2. Transimination of quinone imines: a mechanism for embedding exogenous redox activity into the nucleosome.

    PubMed

    Ye, Wenjie; Seneviratne, Uthpala I; Chao, Ming-Wei; Ravindra, Kodihalli C; Wogan, Gerald N; Tannenbaum, Steven R; Skipper, Paul L

    2012-12-17

    Aminophenols can redox cycle through the corresponding quinone imines to generate ROS. The electrophilic quinone imine intermediate can react with protein thiols as a mechanism of immobilization in vivo. Here, we describe the previously unkown transimination of a quinone imine by lysine as an alternative anchoring mechanism. The redox properties of the condensation product remain largely unchanged because the only structural change to the redox nucleus is the addition of an alkyl substituent to the imine nitrogen. Transimination enables targeting of histone proteins since histones are lysine-rich but nearly devoid of cysteines. Consequently, quinone imines can be embedded in the nucleosome and may be expected to produce ROS in maximal proximity to the genome.

  3. Cyclooxygenase-independent neuroprotective effects of aspirin against dopamine quinone-induced neurotoxicity.

    PubMed

    Asanuma, Masato; Miyazaki, Ikuko; Kikkawa, Yuri; Kimoto, Naotaka; Takeshima, Mika; Murakami, Shinki; Miyoshi, Ko

    2012-09-01

    Prostaglandin H synthase exerts not only cyclooxygenase activity but also peroxidase activity. The latter activity of the enzyme is thought to couple with oxidation of dopamine to dopamine quinone. Therefore, it has been proposed that cyclooxygenase inhibitors could suppress dopamine quinone formation. In the present study, we examined effects of various cyclooxygenase inhibitors against excess methyl L-3,4-dihydroxyphenylalanine (L-DOPA)-induced quinoprotein (protein-bound quinone) formation and neurotoxicity using dopaminergic CATH.a cells. The treatment with aspirin inhibited excess methyl L-DOPA-induced quinoprotein formation and cell death. However, acetaminophen did not show protective effects, and indomethacin and meloxicam rather aggravated these methyl L-DOPA-induced changes. Aspirin and indomethacin did not affect the level of glutathione that exerts quenching dopamine quinone in dopaminergic cells. In contrast with inhibiting effects of higher dose in the previous reports, relatively lower dose of aspirin that affected methyl L-DOPA-induced quinoprotein formation and cell death failed to prevent cyclooxygenase-induced dopamine chrome generation in cell-free system. Furthermore, aspirin but not acetaminophen or meloxicam showed direct dopamine quinone-scavenging effects in dopamine-semiquinone generating systems. The present results suggest that cyclooxygenase shows little contribution to dopamine oxidation in dopaminergic cells and that protective effects of aspirin against methyl L-DOPA-induced dopamine quinone neurotoxicity are based on its cyclooxygenase-independent property.

  4. Elevated Cytoplasmic Free Zinc and Increased Reactive Oxygen Species Generation in the Context of Brain Injury.

    PubMed

    Stork, Christian J; Li, Yang V

    2016-01-01

    Intracellular zinc release and the generation of reactive oxygen species (ROS) have been reported to be common ingredients in numerous toxic signaling mechanisms in neurons. A key source for intracellular zinc release is its liberation from metallothionein-III (MT-III). MT-III binds and regulates intracellular zinc levels under physiological conditions, but the zinc-binding thiols readily react with certain ROS and reactive nitrogen species (RNS) to result in intracellular zinc liberation. Liberated zinc induces ROS and RNS generation by multiple mechanisms, including the induction of mitochondrial ROS production, and also promotes ROS formation outside the mitochondria by interaction with the enzymes NADPH oxidase and 12-lipoxygenase. Of particular relevance to neuronal injury in the context of ischemia and prolonged seizures, the positive feedback cycle between ROS/RNS generation and increasing zinc liberation will be examined.

  5. Generation of reactive oxygen species by interaction between antioxidants used as food additive and metal ions.

    PubMed

    Iwasaki, Yusuke; Oda, Momoko; Tsukuda, Yuri; Nagamori, Yuki; Nakazawa, Hiroyuki; Ito, Rie; Saito, Koichi

    2014-01-01

    Food additives, such as preservatives, sweeteners, coloring agents, and flavoring agents, are widely used in food manufacturing. However, their combined effects on the human body are not known. The purpose of this study was to examine whether combinations of antioxidants and metal ions generate reactive oxygen species (ROS) under in vitro conditions using electron spin resonance (ESR). Among the metal ions examined, only iron and copper generated ROS in the presence of antioxidants. Moreover, certain phenolic antioxidants having pro-oxidant activity induced DNA oxidation and degradation via the generation of high levels of ROS in the presence of copper ion, resulting in complete degradation of DNA in vitro.

  6. Effects of several quinones on insulin aggregation.

    PubMed

    Gong, Hao; He, Zihao; Peng, Anlin; Zhang, Xin; Cheng, Biao; Sun, Yue; Zheng, Ling; Huang, Kun

    2014-07-10

    Protein misfolding and aggregation are associated with more than twenty diseases, such as neurodegenerative diseases and metabolic diseases. The amyloid oligomers and fibrils may induce cell membrane disruption and lead to cell apoptosis. A great number of studies have focused on discovery of amyloid inhibitors which may prevent or treat amyloidosis diseases. Polyphenols have been extensively studied as a class of amyloid inhibitors, with several polyphenols under clinical trials as anti-neurodegenerative drugs. As oxidative intermediates of natural polyphenols, quinones widely exist in medicinal plants or food. In this study, we used insulin as an amyloid model to test the anti-amyloid effects of four simple quinones and four natural anthraquinone derivatives from rhubarb, a traditional herbal medicine used for treating Alzheimer's disease. Our results demonstrated that all eight quinones show inhibitory effects to different extent on insulin oligomerization, especially for 1,4-benzoquinone and 1,4-naphthoquinone. Significantly attenuated oligomerization, reduced amount of amyloid fibrils and reduced hemolysis levels were found after quinones treatments, indicating quinones may inhibit insulin from forming toxic oligomeric species. The results suggest a potential action of native anthraquinone derivatives in preventing protein misfolding diseases, the quinone skeleton may thus be further explored for designing effective anti-amyloidosis compounds.

  7. Multilayer Heterojunction Anodes for Saline Wastewater Treatment: Design Strategies and Reactive Species Generation Mechanisms.

    PubMed

    Yang, Yang; Shin, Jieun; Jasper, Justin T; Hoffmann, Michael R

    2016-08-16

    Multilayer heterojunction SbSn/CoTi/Ir anodes, which consist of Ir0.7Ta0.3O2 bottom layers coated onto a titanium base, Co-TiO2 interlayers, and overcoated discrete Sb-SnO2 islands, were prepared by spray pyrolysis. The Ir0.7Ta0.3O2 bottom layer serves as an Ohmic contact to facilitate electron transfer from semiconductor layers to the Ti base. The Co-TiO2 interlayer and overcoated Sb-SnO2 islands enhance the evolution of reactive chlorine. The surficial Sb-SnO2 islands also serve as the reactive sites for free radical generation. Experiments coupled with computational kinetic simulations show that while ·OH and Cl· are initially produced on the SbSn/CoTi/Ir anode surface, the dominant radical formed in solution is the dichlorine radical anion, Cl2·(-). The steady-state concentration of reactive radicals is 10 orders of magnitude lower than that of reactive chlorine. The SbSn/CoTi/Ir anode was applied to electrochemically treat human wastewater. These test results show that COD and NH4(+) can be removed after 2 h of electrolysis with minimal energy consumption (370 kWh/kg COD and 383 kWh/kg NH4(+)). Although free radical species contribute to COD removal, anodes designed to enhance reactive chlorine production are more effective than those designed to enhance free radical production.

  8. Quinone Reduction by the Na+-Translocating NADH Dehydrogenase Promotes Extracellular Superoxide Production in Vibrio cholerae▿ †

    PubMed Central

    Lin, Po-Chi; Türk, Karin; Häse, Claudia C.; Fritz, Günter; Steuber, Julia

    2007-01-01

    The pathogenicity of Vibrio cholerae is influenced by sodium ions which are actively extruded from the cell by the Na+-translocating NADH:quinone oxidoreductase (Na+-NQR). To study the function of the Na+-NQR in the respiratory chain of V. cholerae, we examined the formation of organic radicals and superoxide in a wild-type strain and a mutant strain lacking the Na+-NQR. Upon reduction with NADH, an organic radical was detected in native membranes by electron paramagnetic resonance spectroscopy which was assigned to ubisemiquinones generated by the Na+-NQR. The radical concentration increased from 0.2 mM at 0.08 mM Na+ to 0.4 mM at 14.7 mM Na+, indicating that the concentration of the coupling cation influences the redox state of the quinone pool in V. cholerae membranes. During respiration, V. cholerae cells produced extracellular superoxide with a specific activity of 10.2 nmol min−1 mg−1 in the wild type compared to 3.1 nmol min−1 mg−1 in the NQR deletion strain. Raising the Na+ concentration from 0.1 to 5 mM increased the rate of superoxide formation in the wild-type V. cholerae strain by at least 70%. Rates of respiratory H2O2 formation by wild-type V. cholerae cells (30.9 nmol min−1 mg−1) were threefold higher than rates observed with the mutant strain lacking the Na+-NQR (9.7 nmol min−1 mg−1). Our study shows that environmental Na+ could stimulate ubisemiquinone formation by the Na+-NQR and hereby enhance the production of reactive oxygen species formed during the autoxidation of reduced quinones. PMID:17322313

  9. Function of isoprenoid quinones and chromanols during oxidative stress in plants.

    PubMed

    Kruk, Jerzy; Szymańska, Renata; Nowicka, Beatrycze; Dłużewska, Jolanta

    2016-09-25

    Isoprenoid quinones and chromanols in plants fulfill both signaling and antioxidant functions under oxidative stress. The redox state of the plastoquinol pool (PQ-pool), which is modulated by interaction with reactive oxygen species (ROS) during oxidative stress, has a major regulatory function in both short- and long-term acclimatory responses. By contrast, the scavenging of ROS by prenyllipids affects signaling pathways where ROS play a role as signaling molecules. As the primary antioxidants, isoprenoid quinones and chromanols are synthesized under high-light stress in response to any increased production of ROS. During photo-oxidative stress, these prenyllipids are continuously synthesized and oxidized to other compounds. In turn, their oxidation products (hydroxy-plastochromanol, plastoquinol-C, plastoquinone-B) can still have an antioxidant function. The oxidation products of isoprenoid quinones and chromanols formed specifically in the face of singlet oxygen, can be indicators of singlet oxygen stress.

  10. TC and H NMR studies of PQQ and selected derivatives. [Pyrroloquinoline quinone

    SciTech Connect

    Houck, D.R.; Unkefer, C.J.

    1988-01-01

    The ortho-quinone structure of pyrroloquinoline quinone (PQQ) is famous for its reactivity with nucleophilic species of carbon, nitrogen, and oxygen(Duine et. al. 1987). In fact, the crystal structure of PQQ was solved in the form of the C-5 acetone adduct(Salisbury et. al 1979). The propensity of the ortho-quinone to accept nucleophiles is the chemical basis of the function of PQQ at enzyme active sites. The present study focuses on the NMR of PQQ and various derivatives formed with oxygen and nitrogen nucleophiles. Our goals are to assign the H, TC, and VN NMR spectra and to rigorously confirm the structures of the adducts. Once the NMR data of the relevant adducts are well defined, we will use TC and VN labeled substrates to probe the active sites of PQQ containing enzymes. 7 refs., 2 figs., 1 tab.

  11. Reactive species in non-equilibrium atmospheric-pressure plasmas: Generation, transport, and biological effects

    NASA Astrophysics Data System (ADS)

    Lu, X.; Naidis, G. V.; Laroussi, M.; Reuter, S.; Graves, D. B.; Ostrikov, K.

    2016-05-01

    Non-equilibrium atmospheric-pressure plasmas have recently become a topical area of research owing to their diverse applications in health care and medicine, environmental remediation and pollution control, materials processing, electrochemistry, nanotechnology and other fields. This review focuses on the reactive electrons and ionic, atomic, molecular, and radical species that are produced in these plasmas and then transported from the point of generation to the point of interaction with the material, medium, living cells or tissues being processed. The most important mechanisms of generation and transport of the key species in the plasmas of atmospheric-pressure plasma jets and other non-equilibrium atmospheric-pressure plasmas are introduced and examined from the viewpoint of their applications in plasma hygiene and medicine and other relevant fields. Sophisticated high-precision, time-resolved plasma diagnostics approaches and techniques are presented and their applications to monitor the reactive species and plasma dynamics in the plasma jets and other discharges, both in the gas phase and during the plasma interaction with liquid media, are critically reviewed. The large amount of experimental data is supported by the theoretical models of reactive species generation and transport in the plasmas, surrounding gaseous environments, and plasma interaction with liquid media. These models are presented and their limitations are discussed. Special attention is paid to biological effects of the plasma-generated reactive oxygen and nitrogen (and some other) species in basic biological processes such as cell metabolism, proliferation, survival, etc. as well as plasma applications in bacterial inactivation, wound healing, cancer treatment and some others. Challenges and opportunities for theoretical and experimental research are discussed and the authors' vision for the emerging convergence trends across several disciplines and application domains is presented to

  12. A novel coumarin-quinone derivative SV37 inhibits CDC25 phosphatases, impairs proliferation, and induces cell death.

    PubMed

    Bana, Emilie; Sibille, Estelle; Valente, Sergio; Cerella, Claudia; Chaimbault, Patrick; Kirsch, Gilbert; Dicato, Mario; Diederich, Marc; Bagrel, Denyse

    2015-03-01

    Cell division cycle (CDC) 25 proteins are key phosphatases regulating cell cycle transition and proliferation by regulating CDK/cyclin complexes. Overexpression of these enzymes is frequently observed in cancer and is related to aggressiveness, high-grade tumors and poor prognosis. Thus, targeting CDC25 by compounds, able to inhibit their activity, appears a good therapeutic approach. Here, we describe the synthesis of a new inhibitor (SV37) whose structure is based on both coumarin and quinone moieties. An analytical in vitro approach shows that this compound efficiently inhibits all three purified human CDC25 isoforms (IC50 1-9 µM) in a mixed-type mode. Moreover, SV37 inhibits growth of breast cancer cell lines. In MDA-MB-231 cells, reactive oxygen species generation is followed by pCDK accumulation, a mark of CDC25 dysfunction. Eventually, SV37 treatment leads to activation of apoptosis and DNA cleavage, underlining the potential of this new type of coumarin-quinone structure.

  13. Hydrogen peroxide formation in a surrogate lung fluid by transition metals and quinones present in particulate matter.

    PubMed

    Charrier, Jessica G; McFall, Alexander S; Richards-Henderson, Nicole K; Anastasio, Cort

    2014-06-17

    Inhaled ambient particulate matter (PM) causes adverse health effects, possibly by generating reactive oxygen species (ROS), including hydrogen peroxide (HOOH), in the lung lining fluid. There are conflicting reports in the literature as to which chemical components of PM can chemically generate HOOH in lung fluid mimics. It is also unclear which redox-active species are most important for HOOH formation at concentrations relevant to ambient PM. To address this, we use a cell-free, surrogate lung fluid (SLF) to quantify the initial rate of HOOH formation from 10 transition metals and 4 quinones commonly identified in PM. Copper, 1,2-naphthoquinone, 1,4-naphthoquinone, and phenanthrenequinone all form HOOH in a SLF, but only copper and 1,2-naphthoquinone are likely important at ambient concentrations. Iron suppresses HOOH formation in laboratory solutions, but has a smaller effect in ambient PM extracts, possibly because organic ligands in the particles reduce the reactivity of iron. Overall, copper produces the majority of HOOH chemically generated from typical ambient PM while 1,2-naphthoquinone generally makes a small contribution. However, measured rates of HOOH formation in ambient particle extracts are lower than rates calculated from soluble copper by an average (±1σ) of 44 ± 22%; this underestimate is likely due to either HOOH destruction by Fe or a reduction in Cu reactivity due to organic ligands from the PM.

  14. Hydrogen Peroxide Formation in a Surrogate Lung Fluid by Transition Metals and Quinones Present in Particulate Matter

    PubMed Central

    2015-01-01

    Inhaled ambient particulate matter (PM) causes adverse health effects, possibly by generating reactive oxygen species (ROS), including hydrogen peroxide (HOOH), in the lung lining fluid. There are conflicting reports in the literature as to which chemical components of PM can chemically generate HOOH in lung fluid mimics. It is also unclear which redox-active species are most important for HOOH formation at concentrations relevant to ambient PM. To address this, we use a cell-free, surrogate lung fluid (SLF) to quantify the initial rate of HOOH formation from 10 transition metals and 4 quinones commonly identified in PM. Copper, 1,2-naphthoquinone, 1,4-naphthoquinone, and phenanthrenequinone all form HOOH in a SLF, but only copper and 1,2-naphthoquinone are likely important at ambient concentrations. Iron suppresses HOOH formation in laboratory solutions, but has a smaller effect in ambient PM extracts, possibly because organic ligands in the particles reduce the reactivity of iron. Overall, copper produces the majority of HOOH chemically generated from typical ambient PM while 1,2-naphthoquinone generally makes a small contribution. However, measured rates of HOOH formation in ambient particle extracts are lower than rates calculated from soluble copper by an average (±1σ) of 44 ± 22%; this underestimate is likely due to either HOOH destruction by Fe or a reduction in Cu reactivity due to organic ligands from the PM. PMID:24857372

  15. Effects of Surface Chemistry on the Generation of Reactive Oxygen Species by Copper Nanoparticles

    PubMed Central

    Shi, Miao; Kwon, Hyun Soo; Peng, Zhenmeng; Elder, Alison; Yang, Hong

    2012-01-01

    Mercaptocarboxylic acids with different carbon chain lengths were used for stabilizing uniform 15 nm copper nanoparticles. The effects of surface chemistry such as ligand type and surface oxidation on the reactive oxygen species (ROS) generated by the copper nanoparticles were examined. Transmission electron microscopy (TEM), Powder X-ray diffraction (PXRD), UV-vis spectroscopy, and an acellular ROS assay show that ROS generation is closely related to the surface oxidation of copper nanoparticles. It was found that the copper nanoparticles with longer chain ligands had surfaces that were better protected from oxidation and a corresponding lower ROS generating capacity than did particles with shorter chain ligands. Conversely, the copper nanoparticles with greater surface oxidation also had higher ROS generating capacity. PMID:22390268

  16. Antioxidant and pro-oxidant properties of pyrroloquinoline quinone (PQQ): implications for its function in biological systems.

    PubMed

    He, Kai; Nukada, Hitoshi; Urakami, Teiji; Murphy, Michael P

    2003-01-01

    Pyrroloquinoline quinone (PQQ) is a novel redox cofactor recently found in human milk. It has been reported to function as an essential nutrient, antioxidant and redox modulator in cell culture experiments and in animal models of human diseases. As mitochondria are particularly susceptible to oxidative damage we studied the antioxidant properties of PQQ in isolated rat liver mitochondria. PQQ was an effective antioxidant protecting mitochondria against oxidative stress-induced lipid peroxidation, protein carbonyl formation and inactivation of the mitochondrial respiratory chain. In contrast, PQQ caused extensive cell death to cells in culture. This surprising effect was inhibited by catalase, and was shown to be due to the generation of hydrogen peroxide during the autoxidation of PQQ in culture medium. We conclude that the reactivities of PQQ are dependent on its environment and that it can act as an antioxidant or a pro-oxidant in different biological systems.

  17. Photoluminescent Gold Nanoclusters in Cancer Cells: Cellular Uptake, Toxicity, and Generation of Reactive Oxygen Species.

    PubMed

    Matulionyte, Marija; Dapkute, Dominyka; Budenaite, Laima; Jarockyte, Greta; Rotomskis, Ricardas

    2017-02-10

    In recent years, photoluminescent gold nanoclusters have attracted considerable interest in both fundamental biomedical research and practical applications. Due to their ultrasmall size, unique molecule-like optical properties, and facile synthesis gold nanoclusters have been considered very promising photoluminescent agents for biosensing, bioimaging, and targeted therapy. Yet, interaction of such ultra-small nanoclusters with cells and other biological objects remains poorly understood. Therefore, the assessment of the biocompatibility and potential toxicity of gold nanoclusters is of major importance before their clinical application. In this study, the cellular uptake, cytotoxicity, and intracellular generation of reactive oxygen species (ROS) of bovine serum albumin-encapsulated (BSA-Au NCs) and 2-(N-morpholino) ethanesulfonic acid (MES)capped photoluminescent gold nanoclusters (Au-MES NCs) were investigated. The results showed that BSA-Au NCs accumulate in cells in a similar manner as BSA alone, indicating an endocytotic uptake mechanism while ultrasmall Au-MES NCs were distributed homogeneously throughout the whole cell volume including cell nucleus. The cytotoxicity of BSA-Au NCs was negligible, demonstrating good biocompatibility of such BSA-protected Au NCs. In contrast, possibly due to ultrasmall size and thin coating layer, Au-MES NCs exhibited exposure time-dependent high cytotoxicity and higher reactivity which led to highly increased generation of reactive oxygen species. The results demonstrate the importance of the coating layer to biocompatibility and toxicity of ultrasmall photoluminescent gold nanoclusters.

  18. Photoluminescent Gold Nanoclusters in Cancer Cells: Cellular Uptake, Toxicity, and Generation of Reactive Oxygen Species

    PubMed Central

    Matulionyte, Marija; Dapkute, Dominyka; Budenaite, Laima; Jarockyte, Greta; Rotomskis, Ricardas

    2017-01-01

    In recent years, photoluminescent gold nanoclusters have attracted considerable interest in both fundamental biomedical research and practical applications. Due to their ultrasmall size, unique molecule-like optical properties, and facile synthesis gold nanoclusters have been considered very promising photoluminescent agents for biosensing, bioimaging, and targeted therapy. Yet, interaction of such ultra-small nanoclusters with cells and other biological objects remains poorly understood. Therefore, the assessment of the biocompatibility and potential toxicity of gold nanoclusters is of major importance before their clinical application. In this study, the cellular uptake, cytotoxicity, and intracellular generation of reactive oxygen species (ROS) of bovine serum albumin-encapsulated (BSA-Au NCs) and 2-(N-morpholino) ethanesulfonic acid (MES)-capped photoluminescent gold nanoclusters (Au-MES NCs) were investigated. The results showed that BSA-Au NCs accumulate in cells in a similar manner as BSA alone, indicating an endocytotic uptake mechanism while ultrasmall Au-MES NCs were distributed homogeneously throughout the whole cell volume including cell nucleus. The cytotoxicity of BSA-Au NCs was negligible, demonstrating good biocompatibility of such BSA-protected Au NCs. In contrast, possibly due to ultrasmall size and thin coating layer, Au-MES NCs exhibited exposure time-dependent high cytotoxicity and higher reactivity which led to highly increased generation of reactive oxygen species. The results demonstrate the importance of the coating layer to biocompatibility and toxicity of ultrasmall photoluminescent gold nanoclusters. PMID:28208642

  19. Comparison of stainless and mild steel welding fumes in generation of reactive oxygen species

    PubMed Central

    2010-01-01

    Background Welding fumes consist of a wide range of complex metal oxide particles which can be deposited in all regions of the respiratory tract. The welding aerosol is not homogeneous and is generated mostly from the electrode/wire. Over 390,000 welders were reported in the U.S. in 2008 while over 1 million full-time welders were working worldwide. Many health effects are presently under investigation from exposure to welding fumes. Welding fume pulmonary effects have been associated with bronchitis, metal fume fever, cancer and functional changes in the lung. Our investigation focused on the generation of free radicals and reactive oxygen species from stainless and mild steel welding fumes generated by a gas metal arc robotic welder. An inhalation exposure chamber located at NIOSH was used to collect the welding fume particles. Results Our results show that hydroxyl radicals (.OH) were generated from reactions with H2O2 and after exposure to cells. Catalase reduced the generation of .OH from exposed cells indicating the involvement of H2O2. The welding fume suspension also showed the ability to cause lipid peroxidation, effect O2 consumption, induce H2O2 generation in cells, and cause DNA damage. Conclusion Increase in oxidative damage observed in the cellular exposures correlated well with .OH generation in size and type of welding fumes, indicating the influence of metal type and transition state on radical production as well as associated damage. Our results demonstrate that both types of welding fumes are able to generate ROS and ROS-related damage over a range of particle sizes; however, the stainless steel fumes consistently showed a significantly higher reactivity and radical generation capacity. The chemical composition of the steel had a significant impact on the ROS generation capacity with the stainless steel containing Cr and Ni causing more damage than the mild steel. Our results suggest that welding fumes may cause acute lung injury. Since type of

  20. 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.

  1. A microfluidic chip for generating reactive plasma at gas-gas interface formed in laminar flow

    NASA Astrophysics Data System (ADS)

    Hashimoto, Masahiro; Tsukasaki, Katsuki; Kumagai, Shinya; Sasaki, Minoru

    2015-01-01

    A gas-gas interface is used for generating a localized reactive plasma flow at an atmospheric pressure. A microfluidic chip is fabricated as the reactor integrating a small plasma source located upstream. Within a Y-shaped microchannel, a discharging gas flows with a chemical gas. Owing to the small width of the microchannel, the gas flow is stabilized in a laminar flow. The resultant gas-gas interface is formed in the area where two gases flow facing each other activating the chemical gas through the energetic species in the discharging gas. A characteristic stream pattern is observed as the etching profile of a carbon film with a sub-µm sharp step change that can be explained by the spatial distribution of the reactive oxygen. This etching profile is different from that obtained when plasma discharging occurs near the channel exit being affected by the turbulent flow.

  2. Light Emitting Diode-Generated Blue Light Modulates Fibrosis Characteristics: Fibroblast Proliferation, Migration Speed, and Reactive Oxygen Species Generation

    PubMed Central

    Mamalis, Andrew; Garcha, Manveer; Jagdeo, Jared

    2016-01-01

    Background and Objective Blue light is part of the visible light spectrum that does not generate harmful DNA adducts associated with skin cancer and photoaging, and may represent a safer therapeutic modality for treatment of keloid scars and other fibrotic skin diseases. Our laboratory previously demonstrated that light-emitting diode (LED) red and infrared light inhibits proliferation of skin fibroblasts. Moreover, different wavelengths of light can produce different biological effects. Furthermore, the effects of LED blue light (LED-BL) on human skin fibroblasts are not well characterized. This study investigated the effects of LED-BL on human skin fibroblast proliferation, viability, migration speed, and reactive oxygen-species (ROS) generation. Methods and Materials Irradiation of adult human skin fibroblasts using commercially-available LED-BL panels was performed in vitro, and modulation of proliferation and viability was quantified using the trypan blue dye exclusion assay, migratory speed was assessed using time-lapse video microscopy, and intracellular ROS generation was measured using the dihydrorhodamine flow cytometry assay. Statistical differences between groups were determined by ANOVA and Student s t-test. Results Human skin fibroblasts treated with LED-BL fluences of 5, 30, 45, and 80 J/cm2 demonstrated statistically significant dose-dependent decreases in relative proliferation of 8.4%, 29.1%, 33.8%, 51.7%, and 55.1%, respectively, compared to temperature and environment matched bench control plates, respectively. LED-BL fluences of 5, 30, 45 and 80 J/cm2 decreased fibroblast migration speed to 95 ± 7.0% (p = 0.64), 81.3 ± 5.5% (p = 0.021), 48.5 ± 2.7% (p < 0.0001), and 32.3 ± 1.9% (p < 0.0001), respectively, relative to matched controls. LED fluences of 5, 10, 30, and 80 J/cm2 resulted in statistically significant increases in reactive oxygen species of 110.4%, 116.6%, 127.5%, and 130%, respectively, relative to bench controls. Conclusion At

  3. Light emitting diode-generated blue light modulates fibrosis characteristics: fibroblast proliferation, migration speed, and reactive oxygen species generation.

    PubMed

    Mamalis, Andrew; Garcha, Manveer; Jagdeo, Jared

    2015-02-01

    Blue light is part of the visible light spectrum that does not generate harmful DNA adducts associated with skin cancer and photoaging, and may represent a safer therapeutic modality for treatment of keloid scars and other fibrotic skin diseases. Our laboratory previously demonstrated that light-emitting diode (LED) red and infrared light inhibits proliferation of skin fibroblasts. Moreover, different wavelengths of light can produce different biological effects. Furthermore, the effects of LED blue light (LED-BL) on human skin fibroblasts are not well characterized. This study investigated the effects of LED-BL on human skin fibroblast proliferation, viability, migration speed, and reactive oxygen-species (ROS) generation. Irradiation of adult human skin fibroblasts using commercially-available LED-BL panels was performed in vitro, and modulation of proliferation and viability was quantified using the trypan blue dye exclusion assay, migratory speed was assessed using time-lapse video microscopy, and intracellular ROS generation was measured using the dihydrorhodamine flow cytometry assay. Statistical differences between groups were determined by ANOVA and Student's t-test. Human skin fibroblasts treated with LED-BL fluences of 5, 10, 15, 30, and 80 J/cm(2) demonstrated statistically significant dose-dependent decreases in relative proliferation of 8.4%, 29.1%, 33.8%, 51.7%, and 55.1%, respectively, compared to temperature and environment matched bench control plates, respectively. LED-BL fluences of 5, 30, 45, and 80 J/cm(2) decreased fibroblast migration speed to 95 ± 7.0% (P = 0.64), 81.3 ± 5.5% (P = 0.021), 48.5 ± 2.7% (P < 0.0001), and 32.3 ± 1.9% (P < 0.0001), respectively, relative to matched controls. LED fluences of 5, 10, 30, and 80 J/cm(2) resulted in statistically significant increases in reactive oxygen species of 110.4%, 116.6%, 127.5%, and 130%, respectively, relative to bench controls. At the fluences

  4. Rates of hydroxyl radical production from transition metals and quinones in a surrogate lung fluid

    PubMed Central

    Charrier, Jessica G.; Anastasio, Cort

    2016-01-01

    Hydroxyl radical (.OH) is the most reactive, and perhaps most detrimental to health, of the reactive oxygen species. .OH production in lungs following inhalation of particulate matter (PM) can result from redox-active chemicals, including iron and copper, but the relative importance of these species is unknown. This work investigates .OH production from iron, copper, and quinones, both individually and in mixtures at atmospherically relevant concentrations. Iron, copper and three of the four quinones (1,2-naphthoquinone, phenanthrenequinone and 1,4-naphthoquinone) produce .OH. Mixtures of copper or quinones with iron synergistically produce .OH at a rate 20 - 130% higher than the sum of the rates of the individual redox-active species. We developed a regression equation from 20 mixtures to predict the rate of .OH production from the particle composition. For typical PM compositions, iron and copper account for most .OH production, while quinones are a minor source, although they can contribute if present at very high concentrations. This work shows that Cu contributes significantly to .OH production in ambient PM; other work has shown that Cu appears to be the primary driver of HOOH production and dithiothreitol (DTT) loss in ambient PM extracts. Taken together, these results indicate that copper appears to be the most important individual contributor to direct oxidant production from inhaled PM. PMID:26153923

  5. Loss of quinone reductase 2 function selectively facilitates learning behaviors.

    PubMed

    Benoit, Charles-Etienne; Bastianetto, Stephane; Brouillette, Jonathan; Tse, YiuChung; Boutin, Jean A; Delagrange, Philippe; Wong, TakPan; Sarret, Philippe; Quirion, Rémi

    2010-09-22

    High levels of reactive oxygen species (ROS) are associated with deficits in learning and memory with age as well as in Alzheimer's disease. Using DNA microarray, we demonstrated the overexpression of quinone reductase 2 (QR2) in the hippocampus in two models of learning deficits, namely the aged memory impaired rats and the scopolamine-induced amnesia model. QR2 is a cytosolic flavoprotein that catalyzes the reduction of its substrate and enhances the production of damaging activated quinone and ROS. QR2-like immunostaining is enriched in cerebral structures associated with learning behaviors, such as the hippocampal formation and the temporofrontal cortex of rat, mouse, and human brains. In cultured rat embryonic hippocampal neurons, selective inhibitors of QR2, namely S26695 and S29434, protected against menadione-induced cell death by reversing its proapoptotic action. S26695 (8 mg/kg) also significantly inhibited scopolamine-induced amnesia. Interestingly, adult QR2 knock-out mice demonstrated enhanced learning abilities in various tasks, including Morris water maze, object recognition, and rotarod performance test. Other behaviors related to anxiety (elevated plus maze), depression (forced swim), and schizophrenia (prepulse inhibition) were not affected in QR2-deficient mice. Together, these data suggest a role for QR2 in cognitive behaviors with QR2 inhibitors possibly representing a novel therapeutic strategy toward the treatment of learning deficits especially observed in the aged brain.

  6. Identification of NAD(P)H quinone oxidoreductase activity in azoreductases from P. aeruginosa: azoreductases and NAD(P)H quinone oxidoreductases belong to the same FMN-dependent superfamily of enzymes.

    PubMed

    Ryan, Ali; Kaplan, Elise; Nebel, Jean-Christophe; Polycarpou, Elena; Crescente, Vincenzo; Lowe, Edward; Preston, Gail M; Sim, Edith

    2014-01-01

    Water soluble quinones are a group of cytotoxic anti-bacterial compounds that are secreted by many species of plants, invertebrates, fungi and bacteria. Studies in a number of species have shown the importance of quinones in response to pathogenic bacteria of the genus Pseudomonas. Two electron reduction is an important mechanism of quinone detoxification as it generates the less toxic quinol. In most organisms this reaction is carried out by a group of flavoenzymes known as NAD(P)H quinone oxidoreductases. Azoreductases have previously been separate from this group, however using azoreductases from Pseudomonas aeruginosa we show that they can rapidly reduce quinones. Azoreductases from the same organism are also shown to have distinct substrate specificity profiles allowing them to reduce a wide range of quinones. The azoreductase family is also shown to be more extensive than originally thought, due to the large sequence divergence amongst its members. As both NAD(P)H quinone oxidoreductases and azoreductases have related reaction mechanisms it is proposed that they form an enzyme superfamily. The ubiquitous and diverse nature of azoreductases alongside their broad substrate specificity, indicates they play a wide role in cellular survival under adverse conditions.

  7. Identification of NAD(P)H Quinone Oxidoreductase Activity in Azoreductases from P. aeruginosa: Azoreductases and NAD(P)H Quinone Oxidoreductases Belong to the Same FMN-Dependent Superfamily of Enzymes

    PubMed Central

    Ryan, Ali; Kaplan, Elise; Nebel, Jean-Christophe; Polycarpou, Elena; Crescente, Vincenzo; Lowe, Edward; Preston, Gail M.; Sim, Edith

    2014-01-01

    Water soluble quinones are a group of cytotoxic anti-bacterial compounds that are secreted by many species of plants, invertebrates, fungi and bacteria. Studies in a number of species have shown the importance of quinones in response to pathogenic bacteria of the genus Pseudomonas. Two electron reduction is an important mechanism of quinone detoxification as it generates the less toxic quinol. In most organisms this reaction is carried out by a group of flavoenzymes known as NAD(P)H quinone oxidoreductases. Azoreductases have previously been separate from this group, however using azoreductases from Pseudomonas aeruginosa we show that they can rapidly reduce quinones. Azoreductases from the same organism are also shown to have distinct substrate specificity profiles allowing them to reduce a wide range of quinones. The azoreductase family is also shown to be more extensive than originally thought, due to the large sequence divergence amongst its members. As both NAD(P)H quinone oxidoreductases and azoreductases have related reaction mechanisms it is proposed that they form an enzyme superfamily. The ubiquitous and diverse nature of azoreductases alongside their broad substrate specificity, indicates they play a wide role in cellular survival under adverse conditions. PMID:24915188

  8. Quinone-Catalyzed Selective Oxidation of Organic Molecules

    PubMed Central

    Wendlandt, Alison E.

    2016-01-01

    Lead In Quinones are common stoichiometric reagents in organic chemistry. High potential para-quinones, such as DDQ and chloranil, are widely used and typically promote hydride abstraction. In recent years, many catalytic applications of these methods have been achieved by using transition metals, electrochemistry or O2 to regenerate the oxidized quinone in situ. Complementary studies have led to the development of a different class of quinones that resemble the ortho-quinone cofactors in Copper Amine Oxidases and mediate efficient and selective aerobic and/or electrochemical dehydrogenation of amines. The latter reactions typically proceed via electrophilic transamination and/or addition-elimination reaction mechanisms, rather than hydride abstraction pathways. The collective observations show that the quinone structure has a significant influence on the reaction mechanism and have important implications for the development of new quinone reagents and quinone-catalyzed transformations. PMID:26530485

  9. Generation of reactive oxygen species and photon emission from a browned product.

    PubMed

    Iida, Tetsuo; Yoshiki, Yumiko; Someya, Shinich; Okubo, Kazuyoshi

    2002-08-01

    The properties of photon emission arising from a browned product were investigated. The photon intensity of the browned product was proportional to the absorbancy at 420 nm, and was influenced by the amino acid structure. The fluorescence spectrum showed similar compounds in the browned product to be related with this photon emission. Superoxide and hydrogen peroxide contributed highly to this photon emission, and several redox compounds enhanced the photon intensity at appropriate concentrations. Our work suggests that the photon intensity was closely related to the reactive oxygen species (ROS) generated from the browned product, and this effect may be utilized to evaluate the function and quality of browned food.

  10. Compensation for Harmonic Currents and Reactive Power in Wind Power Generation System using PWM Inverter

    NASA Astrophysics Data System (ADS)

    Shinohara, Katsuji; Shinhatsubo, Kurato; Iimori, Kenichi; Yamamoto, Kichiro; Saruban, Takamichi; Yamaemori, Takahiro

    In recent year, consciousness of environmental problems is enhancing, and the price of the electric power purchased by an electric power company is established expensive for the power plant utilizing the natural energy. So, the introduction of the wind power generation is promoted in Japan. Generally, squirrel-cage induction machines are widely used as a generator in wind power generation system because of its small size, lightweight and low-cost. However, the induction machines do not have a source of excitation. Thus, it causes the inrush currents and the instantaneous voltage drop when the generator is directly connected to a power grid. To reduce the inrush currents, an AC power regulator is used. Wind power generations are frequently connected to and disconnected from the power grid. However, when the inrush currents are reduced, harmonic currents are caused by phase control of the AC power regulator. And the phase control of AC power regulator cannot control the power factor. Therefore, we propose the use of the AC power regulator to compensate for the harmonic currents and reactive power in the wind power generation system, and demonstrate the validity of its system by simulated and experimental results.

  11. Towards a molecular-level understanding of the reactivity differences for radical anions of juglone and plumbagin: an electrochemical and spectroelectrochemical approach.

    PubMed

    Hernández-Muñoz, Lindsay S; Gómez, Martín; González, Felipe J; González, Ignacio; Frontana, Carlos

    2009-05-07

    An electrochemical and spectroelectrochemical strategy is presented for evaluating reactivity differences in the semiquinone anions from naturally occurring quinones juglone (5-hydroxy-1,4-naphthoquinone) and plumbagin (2-methyl-5-hydroxy-1,4-naphthoquinone). By employing cyclic voltammetry and in situ spectroelectrochemical electron spin resonance measurements, it was found that while semiquinone species generated from plumbagin are stable radical anions in DMSO solution, the species generated from juglone are more reactive. These latter species are involved in a self-protonation process involving a slow rate of protonation (1.8-2.1 mol L(-1)) due to the mild acidity of the OH group at the C-5 position. This result is important when considering observed differences in biochemical reactivity for these quinones, particularly in cases where mediated cytotoxic action is provoked by these agents, as is discussed in this work.

  12. Chemically reactive species in liquids generated by atmospheric-pressure plasmas and their roles in plasma medicine

    NASA Astrophysics Data System (ADS)

    Hamaguchi, Satoshi

    2013-07-01

    Plasmas whose gas temperatures are close to room temperature may be generated in ambient air or a gas at atmospheric pressure with the use of low-frequency high voltage or low-power radio-frequency (RF) or microwave power applied to electrodes. Such plasmas can serve as a powerful source of free radicals and/or chemically reactive species that arise from atoms and molecules of the ambient gas. Recently use of such plasmas for medical purposes has attracted much attention as they can be implemented in possible medical devices that can cause blood coagulation, heal wounds, facilitate angiogenesis, sterilize surgical devices as well as living tissues without harming healthy cells, and selectively inactivate cancer cells. Especially of interest among reactive species generated by atmospheric-pressure plasmas (APP) are reactive oxygen species (ROS) and reactive nitrogen species (RNS) that are generated in liquid phase. Since most living tissues and cells are immersed in liquids (such as blood or culture media), reactive species generated by APPs in the gas phase are transported to the liquid phase and possibly converted to different types of reactive species therein before causing some influence on the tissues or cells. In this study, the rate equations are solved to evaluate concentrations of various reactive species in pure water that are originated by plasma reactions in atmosphere and possible effects of such species (including ROS/RNS) on living tissues and cells are discussed.

  13. Chemically reactive species in liquids generated by atmospheric-pressure plasmas and their roles in plasma medicine

    SciTech Connect

    Hamaguchi, Satoshi

    2013-07-11

    Plasmas whose gas temperatures are close to room temperature may be generated in ambient air or a gas at atmospheric pressure with the use of low-frequency high voltage or low-power radio-frequency (RF) or microwave power applied to electrodes. Such plasmas can serve as a powerful source of free radicals and/or chemically reactive species that arise from atoms and molecules of the ambient gas. Recently use of such plasmas for medical purposes has attracted much attention as they can be implemented in possible medical devices that can cause blood coagulation, heal wounds, facilitate angiogenesis, sterilize surgical devices as well as living tissues without harming healthy cells, and selectively inactivate cancer cells. Especially of interest among reactive species generated by atmospheric-pressure plasmas (APP) are reactive oxygen species (ROS) and reactive nitrogen species (RNS) that are generated in liquid phase. Since most living tissues and cells are immersed in liquids (such as blood or culture media), reactive species generated by APPs in the gas phase are transported to the liquid phase and possibly converted to different types of reactive species therein before causing some influence on the tissues or cells. In this study, the rate equations are solved to evaluate concentrations of various reactive species in pure water that are originated by plasma reactions in atmosphere and possible effects of such species (including ROS/RNS) on living tissues and cells are discussed.

  14. Symbiotic lactobacilli stimulate gut epithelial proliferation via Nox-mediated generation of reactive oxygen species

    PubMed Central

    Jones, Rheinallt M; Luo, Liping; Ardita, Courtney S; Richardson, Arena N; Kwon, Young Man; Mercante, Jeffrey W; Alam, Ashfaqul; Gates, Cymone L; Wu, Huixia; Swanson, Phillip A; Lambeth, J David; Denning, Patricia W; Neish, Andrew S

    2013-01-01

    The resident prokaryotic microbiota of the metazoan gut elicits profound effects on the growth and development of the intestine. However, the molecular mechanisms of symbiotic prokaryotic–eukaryotic cross-talk in the gut are largely unknown. It is increasingly recognized that physiologically generated reactive oxygen species (ROS) function as signalling secondary messengers that influence cellular proliferation and differentiation in a variety of biological systems. Here, we report that commensal bacteria, particularly members of the genus Lactobacillus, can stimulate NADPH oxidase 1 (Nox1)-dependent ROS generation and consequent cellular proliferation in intestinal stem cells upon initial ingestion into the murine or Drosophila intestine. Our data identify and highlight a highly conserved mechanism that symbiotic microorganisms utilize in eukaryotic growth and development. Additionally, the work suggests that specific redox-mediated functions may be assigned to specific bacterial taxa and may contribute to the identification of microbes with probiotic potential. PMID:24141879

  15. UVB dependence of quantum dot reactive oxygen species generation in common skin cell models

    PubMed Central

    MORTENSEN, LUKE J.; FAULKNOR, RENEA; RAVICHANDRAN, SUPRIYA; ZHENG, HONG; DELOUISE, LISA A.

    2015-01-01

    Studies have shown that UVB can slightly increase the penetration of nanoparticles through skin and significantly alter skin cell biology, thus it is important to understand if and how UVB may impact subsequent nanoparticle skin cell interactions. The research presented herein evaluates the effect of UVB on quantum dot (QD) uptake and reactive oxygen species (ROS) generation in primary keratinocytes, primary melanocytes, and related cell lines. QD exposure induced cell type dependent ROS responses increased by pre-exposing cells to UVB and correlated with the level of QD uptake. Our results suggest that keratinocytes may be at greater risk for QD induced ROS generation than melanocytes, and raise awareness about the differential cellular effects that topically applied nanomaterials may have on UVB exposed skin. PMID:26485933

  16. The regulation of superoxide generation and nitric oxide synthesis by C-reactive protein.

    PubMed Central

    Ratnam, S; Mookerjea, S

    1998-01-01

    Activated macrophages utilize both reactive oxygen intermediates and reactive oxynitrogen intermediates for defence against microbes. However, simultaneous generation of superoxide (O- 2;) and nitric oxide (NO) could be harmful to host cells due to the production of peroxynitrite, nitrogen dioxide and hydroxyl radicals. Therefore, the regulation of the production of these molecules is critical to host survival. During periods of inflammation or infection, the level of serum C-reactive protein (CRP) increases in many species. Human and rat CRP have been shown to bind and interact with phagocytic cells. Since many of the interactions of CRP involve the binding to the phosphocholine ligand, we studied the role of CRP in O- 2; and NO generation through the modulation of phosphatidylcholine (PC) metabolism in macrophages. This study has shown that, while rat CRP inhibited phorbol myristate acetate- (PMA) induced release of O- 2; by rat macrophages, CRP-treated macrophages released NO in a time- and dose-dependent manner. CRP increased inducible nitric oxide synthase (iNOS) enzyme as well as iNOS mRNA levels in rat macrophages. Tricyclodecan-9-yl-xanthogenate (D609), an inhibitor to PC phospholipase C (PC-PLC), suppressed iNOS induction but enhanced PMA-induced release of O- 2;. These data indicate that an increased level of CRP during periods of inflammation may result in differential regulation of macrophage NADPH oxidase and iNOS activity. Increased hepatic synthesis of CRP may contribute to the mechanism by which phagocytic cells avoid simultaneous O- 2; and NO synthesis, and this could possibly be mediated through the regulation of PC-PLC. Images Figure 4 Figure 5 PMID:9767445

  17. Resveratrol attenuates azidothymidine-induced cardiotoxicity by decreasing mitochondrial reactive oxygen species generation in human cardiomyocytes

    PubMed Central

    GAO, RACHEL YUE; MUKHOPADHYAY, PARTHA; MOHANRAJ, RAJESH; WANG, HUA; HORVÁTH, BÉLA; YIN, SHI; PACHER, PÁL

    2011-01-01

    Nucleotide reverse transcriptase inhibitors, such as zidovudine (azidothymidine, AZT) and stavudine, represent a class of approved antiretroviral agents for highly active antiretroviral therapy, which prolongs the life expectancy of patients infected with human-immunodeficiency virus. Unfortunately, the use of these drugs is associated with known toxicities in the liver, skeletal muscle, heart and other organs, which may involve increased reactive oxygen species (ROS) generation, among other mechanisms. Resveratrol is a polyphenolic plant-derived antioxidant abundantly found in certain grapes, roots, berries, peanuts and red wine. This study, using primary human cardiomyocytes, evaluated the effects of AZT and pre-treatment with resveratrol on mitochondrial ROS generation and the cell death pathways. AZT induced concentration-dependent cell death, involving both caspase-3 and -7 and poly(ADP-ribose) polymerase activation, coupled with increased mitochondrial ROS generation in human cardiomyocytes. These effects of AZT on mitochondrial ROS generation and cell death may be attenuated by resveratrol pre-treatment. The results demonstrate that mitochondrial ROS generation plays a pivotal role in the cardiotoxicity of AZT in human cardiomyocytes, and resveratrol may provide a potential strategy to attenuate these pathological alterations, which are associated with widely used antiretroviral therapy. PMID:21461578

  18. Resveratrol attenuates azidothymidine-induced cardiotoxicity by decreasing mitochondrial reactive oxygen species generation in human cardiomyocytes.

    PubMed

    Gao, Rachel Yue; Mukhopadhyay, Partha; Mohanraj, Rajesh; Wang, Hua; Horváth, Béla; Yin, Shi; Pacher, Pál

    2011-01-01

    Nucleotide reverse transcriptase inhibitors, such as zidovudine (azidothymidine, AZT) and stavudine, represent a class of approved antiretroviral agents for highly active antiretroviral therapy, which prolongs the life expectancy of patients infected with human-immunodeficiency virus. Unfortunately, the use of these drugs is associated with known toxicities in the liver, skeletal muscle, heart and other organs, which may involve increased reactive oxygen species (ROS) generation, among other mechanisms. Resveratrol is a polyphenolic plant-derived antioxidant abundantly found in certain grapes, roots, berries, peanuts and red wine. This study, using primary human cardiomyocytes, evaluated the effects of AZT and pre-treatment with resveratrol on mitochondrial ROS generation and the cell death pathways. AZT induced concentration-dependent cell death, involving both caspase-3 and -7 and poly(ADP-ribose) polymerase activation, coupled with increased mitochondrial ROS generation in human cardiomyocytes. These effects of AZT on mitochondrial ROS generation and cell death may be attenuated by resveratrol pre-treatment. The results demonstrate that mitochondrial ROS generation plays a pivotal role in the cardiotoxicity of AZT in human cardiomyocytes, and resveratrol may provide a potential strategy to attenuate these pathological alterations, which are associated with widely used antiretroviral therapy.

  19. Controllable generation of reactive oxygen species by femtosecond-laser irradiation

    SciTech Connect

    Yan, Wei; He, Hao Wang, Yintao; Wang, Yisen; Hu, Minglie; Wang, Chingyue

    2014-02-24

    Femtosecond lasers have been advancing Biophotonics research in the past two decades with multiphoton microscopy, microsurgery, and photodynamic therapy. Nevertheless, laser irradiation is identified to bring photodamage to cells via reactive oxygen species (ROS) generation with unclear mechanism. Meanwhile, currently in biological researches, there is no effective method to provide controllable ROS production precisely, which originally is leaked from mitochondria during respiration and plays a key role in a lot of important cellular processes and cellular signaling pathways. In this study, we show the process of how the tightly focused femtosecond-laser induces ROS generation solely in mitochondria at the very beginning and then release to cytosol if the stimulus is intense enough. At certain weak power levels, the laser pulses induce merely moderate Ca{sup 2+} release but this is necessary for the laser to generate ROS in mitochondria. Cellular original ROS are also involved with a small contribution. When the power is above a threshold, ROS are then released to cytosol, indicating photodamage overwhelming cellular repair ability. The mechanisms in those two cases are quite different. Those results clarify parts of the mechanism in laser-induced ROS generation. Hence, it is possible to further this optical scheme to provide controllable ROS generation for ROS-related biological researches including mitochondrial diseases and aging.

  20. Controllable generation of reactive oxygen species by femtosecond-laser irradiation

    NASA Astrophysics Data System (ADS)

    Yan, Wei; He, Hao; Wang, Yintao; Wang, Yisen; Hu, Minglie; Wang, Chingyue

    2014-02-01

    Femtosecond lasers have been advancing Biophotonics research in the past two decades with multiphoton microscopy, microsurgery, and photodynamic therapy. Nevertheless, laser irradiation is identified to bring photodamage to cells via reactive oxygen species (ROS) generation with unclear mechanism. Meanwhile, currently in biological researches, there is no effective method to provide controllable ROS production precisely, which originally is leaked from mitochondria during respiration and plays a key role in a lot of important cellular processes and cellular signaling pathways. In this study, we show the process of how the tightly focused femtosecond-laser induces ROS generation solely in mitochondria at the very beginning and then release to cytosol if the stimulus is intense enough. At certain weak power levels, the laser pulses induce merely moderate Ca2+ release but this is necessary for the laser to generate ROS in mitochondria. Cellular original ROS are also involved with a small contribution. When the power is above a threshold, ROS are then released to cytosol, indicating photodamage overwhelming cellular repair ability. The mechanisms in those two cases are quite different. Those results clarify parts of the mechanism in laser-induced ROS generation. Hence, it is possible to further this optical scheme to provide controllable ROS generation for ROS-related biological researches including mitochondrial diseases and aging.

  1. Increase of reactive oxygen species generation in cerebral cortex slices after the transiently enhanced metabolic activity.

    PubMed

    Sasaki, Toru; Awaji, Takuji; Shimada, Kazuyoshi; Sasaki, Haruyo

    2017-10-01

    Under certain conditions such as hypoxia-reoxygenation, the generation of reactive oxygen species (ROS) increases following hypoxia caused by a decreased oxygen supply. As another hypoxic condition, an excess neural activity status including epileptic seizure induces a decrease in tissue oxygen partial pressure (pO2) caused by enhanced oxygen utilization; however, whether ROS generation increases following the hypoxic status induced by transiently enhanced energy metabolism in brain tissue currently remains unknown. We herein investigated ROS-dependent chemiluminescence in cerebral cortex slices during the restoration of transiently enhanced energy metabolism induced by a high-potassium treatment with tissue pO2 changes and redox balance. ROS generation in the tissue was enhanced after high-potassium-induced hypoxia, but not by the reversed order of the treatment: control-potassium then high-potassium treatment, high-potassium treatment alone, and control-potassium treatment alone. The high-potassium treatment induced a transient decrease in tissue pO2 and a shift in the tissue redox balance towards reduction. The transient shift in the tissue redox balance towards reduction with enhanced metabolic activity and its recovery may correlate with ROS generation. This phenomenon may mimic ROS generation following the hypoxic status induced by transiently enhanced energy metabolism. Copyright © 2017 Elsevier Ireland Ltd and Japan Neuroscience Society. All rights reserved.

  2. Quantification of reactive oxygen species generation by photoexcitation of PEGylated quantum dots.

    PubMed

    Yaghini, Elnaz; Pirker, Katharina F; Kay, Christopher W M; Seifalian, Alexander M; MacRobert, Alexander J

    2014-12-29

    Photocatalytic generation of reactive oxygen species (ROS) from quantum dots (QDs) has been widely reported yet quantitative studies of ROS formation and their quantum yields are lacking. This study investigates the generation of ROS by water soluble PEGylated CdSe/ZnS QDs with red emission. PEGylation of QDs is commonly used to confer water solubility and minimise uptake by organs of the reticuloendothelial system; therefore studies of ROS formation are of biomedical relevance. Using non-photolytic visible wavelength excitation, the superoxide anion radical is shown to be the primary ROS species generated with a quantum efficiency of 0.35%. The yield can be significantly enhanced in the presence of the electron donor, nicotinamide adenine dinucleotide (NADH), as demonstrated by oxygen consumption measurements and electron paramagnetic resonance spectroscopy with in situ illumination. Direct production of singlet oxygen is not detectable from the QDs alone. A comparison is made with ROS generation by the same QDs complexed with a sulfonated phthalocyanine which can generate singlet oxygen via Förster resonance energy transfer between the QDs and the phthalocyanine. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Spontaneous generation of reactive oxygen species and effect on motility and fertilizability of sea urchin spermatozoa.

    PubMed

    Kazama, Makoto; Sato, Taizo; Hino, Akiya

    2014-05-01

    We investigated the generation of reactive oxygen species (ROS) by spermatozoa in two species of sea urchin. ROS generation was accompanied by the initiation of motility and respiration and influenced the motility and fertilizability of spermatozoa. The sea urchin performs external fertilization in aerobic seawater. Sperm motility was initiated after spawning through Na+/H+ exchange. ROS generation was dependent on the respiration and sperm concentration and its generation was first observed at initiation of motility, via activation of respiration through ATP/ADP transport. The ROS generation rate increased at higher dilution ratios of spermatozoa, in a manner that was synchronous with the respiratory rate. This phenomenon resembled the previously defined 'sperm dilution effect' on respiration. The loss of motility and fertilizability was induced not only by treatment with hydrogen peroxide but also by sperm dilution. Storage of spermatozoa with a higher dilution ratio also accelerated the decrease in fertilizability. Thus, optimum sea urchin fertilizability is maintained by storage of undiluted spermatozoa on ice, in order to minimize oxidative stress and to maximize longevity.

  4. Reactive oxygen species generation is not different during isometric and lengthening contractions of mouse muscle.

    PubMed

    Sloboda, Darcée D; Brooks, Susan V

    2013-10-01

    Skeletal muscles can be injured by lengthening contractions, when the muscles are stretched while activated. Lengthening contractions produce structural damage that leads to the degeneration and regeneration of damaged muscle fibers by mechanisms that have not been fully elucidated. Reactive oxygen species (ROS) generated at the time of injury may initiate degenerative or regenerative processes. In the present study we hypothesized that lengthening contractions that damage the muscle would generate more ROS than isometric contractions that do not cause damage. To test our hypothesis, we subjected muscles of mice to lengthening contractions or isometric contractions and simultaneously monitored intracellular ROS generation with the fluorescent indicator 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein (CM-DCFH), which is oxidized by ROS to form the fluorescent product CM-DCF. We found that CM-DCF fluorescence was not different during or shortly after lengthening contractions compared with isometric controls, regardless of the amount of stretch and damage that occurred during the lengthening contractions. The only exception was that after severe stretches, the increase in CM-DCF fluorescence was impaired. We conclude that lengthening contractions that damage the muscle do not generate more ROS than isometric contractions that do not cause damage. The implication is that ROS generated at the time of injury are not the initiating signals for subsequent degenerative or regenerative processes.

  5. Berberine-induced apoptosis in human prostate cancer cells is initiated by reactive oxygen species generation

    SciTech Connect

    Meeran, Syed M.; Katiyar, Suchitra; Katiyar, Santosh K.

    2008-05-15

    Phytochemicals show promise as potential chemopreventive or chemotherapeutic agents against various cancers. Here we report the chemotherapeutic effects of berberine, a phytochemical, on human prostate cancer cells. The treatment of human prostate cancer cells (PC-3) with berberine induced dose-dependent apoptosis but this effect of berberine was not seen in non-neoplastic human prostate epithelial cells (PWR-1E). Berberine-induced apoptosis was associated with the disruption of the mitochondrial membrane potential, release of apoptogenic molecules (cytochrome c and Smac/DIABLO) from mitochondria and cleavage of caspase-9,-3 and PARP proteins. This effect of berberine on prostate cancer cells was initiated by the generation of reactive oxygen species (ROS) irrespective of their androgen responsiveness, and the generation of ROS was through the increased induction of xanthine oxidase. Treatment of cells with allopurinol, an inhibitor of xanthine oxidase, inhibited berberine-induced oxidative stress in cancer cells. Berberine-induced apoptosis was blocked in the presence of antioxidant, N-acetylcysteine, through the prevention of disruption of mitochondrial membrane potential and subsequently release of cytochrome c and Smac/DIABLO. In conclusion, the present study reveals that the berberine-mediated cell death of human prostate cancer cells is regulated by reactive oxygen species, and therefore suggests that berberine may be considered for further studies as a promising therapeutic candidate for prostate cancer.

  6. Intracellular reactive oxygen species in monocytes generated by photosensitive chromophores activated with blue light.

    PubMed

    Bouillaguet, Serge; Owen, Brandi; Wataha, John C; Campo, Marino A; Lange, Norbert; Schrenzel, Jacques

    2008-08-01

    Disinfection of the tooth pulp-canal system is imperative to successful endodontic therapy. Yet, studies suggest that 30-50% of current endodontic treatments fail from residual bacterial infection. Photodynamic therapy using red-light chromophores (630 nm) to induce antimicrobial death mediated by generated reactive oxygen species (ROS) has been reported, but red-light also may thermally damage resident tissues. In the current study, we tested the hypothesis that several blue light chromophores (380-500 nm) generate intracellular reactive oxygen species but are not cytotoxic to mammalian cells. THP1 monocytes were exposed to 10 microM of four chromophores (chlorin e6, pheophorbide-a, pheophorbide-a-PLL, and riboflavin) for 30 min before activation with blue light (27J/cm(2), 60s). After activation, intracellular ROS were measured using a dihydrofluorescein diacetate technique, and cytotoxicity was determined by measuring mitochondrial activity with the MTT method. All photosensitizers produced intracellular ROS levels that were dependent on both the presence of the photosensitizer and blue light exposure. Riboflavin and pheophorbide-a-PLL produced the highest levels of ROS. Photosensitizers except riboflavin exhibited cytotoxicity above 10 microM, and all except pheophorbide-a-PLL were more cytotoxic after blue light irradiation. The current study demonstrated the possible utility of blue light chromophores as producers of ROS that would be useful for endodontic disinfection.

  7. Detecting, visualizing and quantitating the generation of reactive oxygen species in an amoeba model system.

    PubMed

    Zhang, Xuezhi; Soldati, Thierry

    2013-11-05

    Reactive oxygen species (ROS) comprise a range of reactive and short-lived, oxygen-containing molecules, which are dynamically interconverted or eliminated either catalytically or spontaneously. Due to the short life spans of most ROS and the diversity of their sources and subcellular localizations, a complete picture can be obtained only by careful measurements using a combination of protocols. Here, we present a set of three different protocols using OxyBurst Green (OBG)-coated beads, or dihydroethidium (DHE) and Amplex UltraRed (AUR), to monitor qualitatively and quantitatively various ROS in professional phagocytes such as Dictyostelium. We optimised the beads coating procedures and used OBG-coated beads and live microscopy to dynamically visualize intraphagosomal ROS generation at the single cell level. We identified lipopolysaccharide (LPS) from E. coli as a potent stimulator for ROS generation in Dictyostelium. In addition, we developed real time, medium-throughput assays using DHE and AUR to quantitatively measure intracellular superoxide and extracellular H2O2 production, respectively.

  8. Theoretical estimation of redox potential of biological quinone cofactors.

    PubMed

    Gillet, Natacha; Lévy, Bernard; Moliner, Vicent; Demachy, Isabelle; de la Lande, Aurélien

    2017-07-05

    Redox potentials are essential to understand biological cofactor reactivity and to predict their behavior in biological media. Experimental determination of redox potential in biological system is often difficult due to complexity of biological media but computational approaches can be used to estimate them. Nevertheless, the quality of the computational methodology remains a key issue to validate the results. Instead of looking to the best absolute results, we present here the calibration of theoretical redox potential for quinone derivatives in water coupling QM + MM or QM/MM scheme. Our approach allows using low computational cost theoretical level, ideal for long simulations in biological systems, and determination of the uncertainties linked to the calculations. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  9. Chlorophyll-quinone photochemistry in liposomes: mechanisms of radical formation and decay

    SciTech Connect

    Hurley, J.K.; Tollin, G.

    1980-01-01

    Laser flash photolysis has been used to investigate the mechanism of formation and decay of the radical species generated by light induced electron transfer from chlorophyll a triplet to quinone in egg phosphatidyl choline bilayer vesicles. Chlorophyll triplet quenching by quinone is controlled by diffusion occurring within the bilayer membrane and reflects bilayer viscosity. Radical formation via separation of the intermediate ion pair is also inhibited by increased bilayer viscosity. Cooperativity is observed in this process due to an enhancement of radical separation by electron transfer from semiquinone anion radical to a neighboring quinone molecule. Two modes of radical decay are observed, a rapid recombination occurring within the bilayer and a much slower recombination occurring across the bilayer. The slow decay is only observed with quinones which are not tightly anchored into the bilayer, and is probably the result of electron transfer from semiquinone anion radical formed within the bilayer to a quinone molecule residing at the bilayer-water interface. With benzoquinone, approximately 60% of the radical decay occurs via the slow mode. Triplet to radical conversion efficiencies in the bilayer systems are comparable to those obtained in fluid solution (approx. 60%). However, radical recombination, at least for the slow decay mechanism, is considerably retarded.

  10. Programmed cell death in plants: protective effect of mitochondrial-targeted quinones.

    PubMed

    Vasil'ev, L A; Dzyubinskaya, E V; Kiselevsky, D B; Shestak, A A; Samuilov, V D

    2011-10-01

    Ubiquinone or plastoquinone covalently linked to synthetic decyltriphenylphosphonium (DTPP(+)) or rhodamine cations prevent programmed cell death (PCD) in pea leaf epidermis induced by chitosan or CN(-). PCD was monitored by recording the destruction of cell nuclei. CN(-) induced the destruction of nuclei in both epidermal cells (EC) and guard cells (GC), whereas chitosan destroyed nuclei in EC not in GC. The half-maximum concentrations for the protective effects of the quinone derivatives were within the pico- and nanomolar range. The protective effect of the quinones was removed by a protonophoric uncoupler and reduced by tetraphenylphosphonium cations. CN(-)-Induced PCD was accelerated by the tested quinone derivatives at concentrations above 10(-8)-10(-7) M. Unlike plastoquinone linked to the rhodamine cation (SkQR1), DTPP(+) derivatives of quinones suppressed menadione-induced H(2)O(2) generation in the cells. The CN(-)-induced destruction of GC nuclei was prevented by DTPP(+) derivatives in the dark not in the light. SkQR1 inhibited this process both in the dark and in the light, and its effect in the light was similar to that of rhodamine 6G. The data on the protective effect of cationic quinone derivatives indicate that mitochondria are involved in PCD in plants.

  11. Quinones: reactions with hemoglobin, effects within erythrocytes and potential for antimalarial development

    SciTech Connect

    Denny, B.J.

    1986-01-01

    The focus of this research was to characterize the interactions of some simple quinone like compounds with purified hemoglobin and to study the effects of these compounds within erythrocytes. It is proposed that these sorts of agents can have an antimalarial effect. The simplest compounds chosen for study were benzoquinone, methylquinone (toluquinone) and hydroquinone. When /sup 14/C-quinone was reacted with purified hemoglobin (Hb) there was rapid binding of the first two moles of substrate per Hb molecule. An unusual property of the modified Hb's is that in the presence of a redox sensitive agent such as cytochrome c they are capable of generating superoxide anions. Within erythrocytes, quinone and toluquinone which differ only by a single methyl group have completely different effects. Toluquinone causes the cells to hemolyse and the effect was enhanced when the erythrocyte superoxide dismutase was inhibited; the effect was diminished when scavengers of activated oxygen such as histidine, mannitol and vital E were present. Benzoquinone on the other hand did not cause the cells to hemolyse and instead appeared to protect the cells from certain hemolytic stresses. Growth of malaria parasites in erythrocytes has been shown to be inhibited by activated forms of oxygen, also some quinone like agents in the past have been shown to inhibit the parasite's metabolism. An initial experiment with erythrocytes infected with malaria parasites showed that quinone and toluquinone could both inhibit the growth rate of parasites.

  12. Biological Reactive Intermediates (BRIs) Formed from Botanical Dietary Supplements

    PubMed Central

    Dietz, Birgit M.; Bolton, Judy L.

    2013-01-01

    The use of botanical dietary supplements is increasingly popular, due to their natural origin and the perceived assumption that they are safer than prescription drugs. While most botanical dietary supplements can be considered safe, a few contain compounds, which can be converted to reactive biological reactive intermediates (BRIs) causing toxicity. For example, sassafras oil contains safrole, which can be converted to a reactive carbocation forming genotoxic DNA adducts. Alternatively, some botanical dietary supplements contain stable BRIs such as simple Michael acceptors that react with chemosensor proteins such as Keap1 resulting in induction of protective detoxification enzymes. Examples include curcumin from turmeric, xanthohumol from hops, and Z-ligustilide from dang gui. Quinones (sassafras, kava, black cohosh), quinone methides (sassafras), and epoxides (pennyroyal oil) represent BRIs of intermediate reactivity, which could generate both genotoxic and/or chemopreventive effects. The biological targets of BRIs formed from botanical dietary supplements and their resulting toxic and/or chemopreventive effects are closely linked to the reactivity of BRIs as well as dose and time of exposure. PMID:20970412

  13. Benzofuran-, benzothiophene-, indazole- and benzisoxazole-quinones: excellent substrates for NAD(P)H:quinone oxidoreductase 1.

    PubMed

    Newsome, Jeffery J; Hassani, Mary; Swann, Elizabeth; Bibby, Jane M; Beall, Howard D; Moody, Christopher J

    2013-06-01

    A series of heterocyclic quinones based on benzofuran, benzothiophene, indazole and benzisoxazole has been synthesized, and evaluated for their ability to function as substrates for recombinant human NAD(P)H:quinone oxidoreductase (NQO1), a two-electron reductase upregulated in tumor cells. Overall, the quinones are excellent substrates for NQO1, approaching the reduction rates observed for menadione.

  14. Quinone-related hexacyclic by-products in the production process of exemestane.

    PubMed

    Giovenzana, Giovanni Battista; Masciocchi, Norberto; Negri, Roberto; Palmisano, Giovanni; Penoni, Andrea; Toma, Lucio

    2017-04-01

    Exemestane, a 3rd-generation aromatase inhibitor, is clinically used in the treatment of breast cancer in postmenopausal women. The key step of the industrial synthetic process, i.e., a dehydrogenation to introduce the Δ(1)-unsaturation, is normally performed with quinones such as p-chloranil or DDQ. We observed the formation of two different hexacyclic by-products, depending on the quinone used in the oxidation step. These compounds arise from an initial [4+2] cycloaddition between the precursor 6-methylenandrost-4-ene-3,17-dione and the quinone reagent, followed by a twofold dehydrohalogenation (with p-chloranil) or dehydrogenation (with DDQ). The structures of these unprecedented hexacyclic adducts were determined by a combination of mass spectrometry, NMR techniques and crystallographic analysis.

  15. Visible Light Photocatalysis for the Generation and Use of Reactive Azolyl and Polyfluoroaryl Intermediates.

    PubMed

    Arora, Amandeep; Weaver, Jimmie D

    2016-10-18

    Photocatalysis offers several mechanistically unique pathways that are not rivaled by mainstream catalysis. Primarily, the ability to convert photochemical energy into single electron oxidation and reduction events provides a new dimension for chemists to consider when choosing how to activate a molecule or approach a complex synthesis. Since most organic molecules do not absorb light in the visible region, they are impervious to direct visible light photochemistry, which provides an opportunity for photocatalysis in which a visible light absorbing compound can serve as a mediator. In this Account, we discuss the consequences of catalyst mediated, photoinduced electron transfer to several classes of reducible arenes. While the bulk of the work discussed within this Account utilizes iridium-based photocatalysts, in principle the chemistry is not limited to this class of photocatalyst, and the principles should be more general. Instead, this Account focuses largely on the consequences of single electron transfer to poly- and perfluorinated arenes and 2-halo azoles. Electron transfer converts these stable molecules into reactive intermediates whose behavior often depends entirely on the identity of the halogen that undergoes substitution. The result is both diverse chemistry and an alternative way of thinking about the chemical reactivity of these motifs. Specifically, we discuss our efforts and those of others to develop strategies for the generation of radicals or radical anions from perfluoroarenes and azoles and the behavior of these intermediates as implied by reactions in which they participate. The divergent pathway is illustrated by 2-bromoazoles, which yield azolyl radicals and can be utilized for addition to π-bonds, while use of the 2-chloroazole substrate leads to an entirely different reaction profile. Under the appropriate reaction conditions, the reactive and transient intermediates are useful coupling partners and often provide unrivaled access to new

  16. 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.

  17. Differential stress-induced regulation of two quinone reductases in the brown rot Basidiomycete Gloeophyllum trabeum

    Treesearch

    Roni Cohen; Melissa R. Suzuki; Kenneth E. Hammel

    2004-01-01

    Quinone reductases (QRDs) have two important functions in the basidiomycete Gloeophyllum trabeum, which causes brown rot of wood. First, a QRD is required to generate biodegradative hydroxyl radicals via redox cycling between two G. trabeum extracellular metabolites, 2,5-dimethoxyhydroquinone (2,5-DMHQ) and 2,5-dimethoxy-1,4-benzoquinone (2,5- DMBQ). Second, because 2,...

  18. Impact of plasma jet vacuum ultraviolet radiation on reactive oxygen species generation in bio-relevant liquids

    SciTech Connect

    Jablonowski, H.; Hammer, M. U.; Reuter, S.; Bussiahn, R.; Weltmann, K.-D.; Woedtke, Th. von

    2015-12-15

    Plasma medicine utilizes the combined interaction of plasma produced reactive components. These are reactive atoms, molecules, ions, metastable species, and radiation. Here, ultraviolet (UV, 100–400 nm) and, in particular, vacuum ultraviolet (VUV, 10–200 nm) radiation generated by an atmospheric pressure argon plasma jet were investigated regarding plasma emission, absorption in a humidified atmosphere and in solutions relevant for plasma medicine. The energy absorption was obtained for simple solutions like distilled water (dH{sub 2}O) or ultrapure water and sodium chloride (NaCl) solution as well as for more complex ones, for example, Rosewell Park Memorial Institute (RPMI 1640) cell culture media. As moderate stable reactive oxygen species, hydrogen peroxide (H{sub 2}O{sub 2}) was studied. Highly reactive oxygen radicals, namely, superoxide anion (O{sub 2}{sup •−}) and hydroxyl radicals ({sup •}OH), were investigated by the use of electron paramagnetic resonance spectroscopy. All species amounts were detected for three different treatment cases: Plasma jet generated VUV and UV radiation, plasma jet generated UV radiation without VUV part, and complete plasma jet including all reactive components additionally to VUV and UV radiation. It was found that a considerable amount of radicals are generated by the plasma generated photoemission. From the experiments, estimation on the low hazard potential of plasma generated VUV radiation is discussed.

  19. Impact of plasma jet vacuum ultraviolet radiation on reactive oxygen species generation in bio-relevant liquids

    NASA Astrophysics Data System (ADS)

    Jablonowski, H.; Bussiahn, R.; Hammer, M. U.; Weltmann, K.-D.; von Woedtke, Th.; Reuter, S.

    2015-12-01

    Plasma medicine utilizes the combined interaction of plasma produced reactive components. These are reactive atoms, molecules, ions, metastable species, and radiation. Here, ultraviolet (UV, 100-400 nm) and, in particular, vacuum ultraviolet (VUV, 10-200 nm) radiation generated by an atmospheric pressure argon plasma jet were investigated regarding plasma emission, absorption in a humidified atmosphere and in solutions relevant for plasma medicine. The energy absorption was obtained for simple solutions like distilled water (dH2O) or ultrapure water and sodium chloride (NaCl) solution as well as for more complex ones, for example, Rosewell Park Memorial Institute (RPMI 1640) cell culture media. As moderate stable reactive oxygen species, hydrogen peroxide (H2O2) was studied. Highly reactive oxygen radicals, namely, superoxide anion (O2•-) and hydroxyl radicals (•OH), were investigated by the use of electron paramagnetic resonance spectroscopy. All species amounts were detected for three different treatment cases: Plasma jet generated VUV and UV radiation, plasma jet generated UV radiation without VUV part, and complete plasma jet including all reactive components additionally to VUV and UV radiation. It was found that a considerable amount of radicals are generated by the plasma generated photoemission. From the experiments, estimation on the low hazard potential of plasma generated VUV radiation is discussed.

  20. 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.

  1. Reduction in generation of reactive oxygen species and endothelial dysfunction during postprandial state.

    PubMed

    Sodré, F L; Paim, B A; Urban, A; Vercesi, A E; Faria, E C

    2011-10-01

    To characterise changes in generation of cellular reactive oxygen species (ROS) in healthy males during the postprandial state, and to analyse the influence of the postprandial state on endothelial ROS generation and endothelial dysfunction. Seventeen healthy subjects were recruited. Blood samples were collected in the fasting state and 2, 4, 6 and 8h after liquid-meal intake (composition: 25% fat, 55% dextromaltose and 14% protein), providing 40 gfat m(-2) body surface. Plasma lipids, apolipoproteins, glucose and insulin were measured during this period. Peripheral blood mononuclear cells (PBMCs) were isolated by density-gradient centrifugation. The influence of postprandial state on intracellular ROS generation was measured by two different methods in PBMCs and in a human immortalised endothelial cell line (ECV 304). Artery flow-mediated vasodilation (FMD) was used to evaluate the endothelial function, and oxygen consumption by PBMCs was measured. Reduced ROS generation was observed in all methods and cells during the postprandial period. FMD was impaired 8h after meal intake (23±6 vs. 13±2, P<0.05 vs. baseline). The consumption of oxygen was reduced in PBMCs (-14% into 2h, P<0.05 vs. baseline and -27% after 4h, P<0.01 vs. baseline). ROS generation was correlated with plasma lipids, insulin, apolipoproteins and oxygen consumption. In contrast to the previously reported elevation of postprandial oxidative stress, this study shows reduced ROS generation in PBMCs and in ECV 304. Data obtained in both cellular models suggest the existence of a protective response against plasma postprandial oxidative stress. Copyright © 2009 Elsevier B.V. All rights reserved.

  2. Corrosion-induced gas generation in a nuclear waste repository: Reactive geochemistry and multiphase flow effect

    SciTech Connect

    Xu, T.; Senger, R.; Finsterle, S.

    2008-10-15

    Corrosion of steel canisters, stored in a repository for spent fuel and high-level nuclear wastes, leads to the generation and accumulation of hydrogen gas in the backfilled emplacement tunnels, which may significantly affect long-term repository safety. Previous studies used H{sub 2} generation rates based on the volume of the waste or canister material and the stoichiometry of the corrosion reaction. However, iron corrosion and H{sub 2} generation rates vary with time, depending on factors such as amount of iron, water availability, water contact area, and aqueous and solid chemistry. To account for these factors and feedback mechanisms, we developed a chemistry model related to iron corrosion, coupled with two-phase (liquid and gas) flow phenomena that are driven by gas-pressure buildup associated with H{sub 2} generation and water consumption. Results indicate that by dynamically calculating H{sub 2} generation rates based on a simple model of corrosion chemistry, and by coupling this corrosion reaction with two-phase flow processes, the degree and extent of gas pressure buildup could be much smaller compared to a model that neglects the coupling between flow and reactive transport mechanisms. By considering the feedback of corrosion chemistry, the gas pressure increases initially at the canister, but later decreases and eventually returns to a stabilized pressure that is slightly higher than the background pressure. The current study focuses on corrosion under anaerobic conditions for which the coupled hydrogeochemical model was used to examine the role of selected physical parameters on the H{sub 2} gas generation and corresponding pressure buildup in a nuclear waste repository. The developed model can be applied to evaluate the effect of water and mineral chemistry of the buffer and host rock on the corrosion reaction for future site-specific studies.

  3. Rat liver mitochondrial and microsomal tests for the assessment of quinone toxicity

    SciTech Connect

    Bramble, L.A.; Boardman, G.D.; Dietrich, A.M. . Dept. of Civil Engineering); Bevan, D.R. . Dept. of Biochemistry)

    1994-02-01

    Short-term toxicity tests using mitochondrial and microsomal metabolism were developed and applied to a series of eight quinones. In the mitochondrial assay, the degree to which test compounds inhibited mitochondrial respiration varied from an effective concentration (EC50) of 9 to 125 [mu]M. In the microsomal assay, the maximum percentage of increase over control oxygen consumption rates elicited by the quinones ranged from 8 to 837%. The ability of the compounds to stimulate microsomal oxygen uptake reflects their capability to redox cycle and form reactive oxygen species. Results of the mitochondrial and microsomal assay were statistically correlated with several quinone physicochemical parameters and qualitatively compared to reduction potential. The biological response observed in both test systems appeared to be most strongly influenced by the reduction potential of the quinone. Biomechanisms of action were suggested on the basis of this relationship. To assess the ability of the mitochondrial and microsomal assays to indicate toxicity of the quinonoid compounds, results were statistically correlated with literature-derived toxicity data. It was concluded that the mitochondrial assay appears to be a valid indicator of acute toxicity, whereas the microsomal assay better portends the potential for chronic toxicity.

  4. Internally Generated Reactivation of Single Neurons in Human Hippocampus During Free Recall

    PubMed Central

    Gelbard-Sagiv, Hagar; Mukamel, Roy; Harel, Michal; Malach, Rafael; Fried, Itzhak

    2009-01-01

    The emergence of memory, a trace of things past, into human consciousness is one of the greatest mysteries of the human mind. Whereas the neuronal basis of recognition memory can be probed experimentally in human and nonhuman primates, the study of free recall requires that the mind declare the occurrence of a recalled memory (an event intrinsic to the organism and invisible to an observer). Here, we report the activity of single neurons in the human hippocampus and surrounding areas when subjects first view cinematic episodes consisting of audiovisual sequences and again later when they freely recall these episodes. A subset of these neurons exhibited selective firing, which often persisted throughout and following specific episodes for as long as 12 seconds. Verbal reports of memories of these specific episodes at the time of free recall were preceded by selective reactivation of the same hippocampal and entorhinal cortex neurons. We suggest that this reactivation is an internally generated neuronal correlate for the subjective experience of spontaneous emergence of human recollection. PMID:18772395

  5. 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.

  6. Manipulating the selection forces during affinity maturation to generate cross-reactive HIV antibodies

    PubMed Central

    Wang, Shenshen; Mata-Fink, Jordi; Kriegsman, Barry; Hanson, Melissa; Irvine, Darrell J.; Eisen, Herman N.; Burton, Dennis R.; Wittrup, K. Dane; Kardar, Mehran; Chakraborty, Arup K.

    2015-01-01

    Summary Generation of potent antibodies by a mutation-selection process called affinity maturation is a key component of effective immune responses. Antibodies that protect against highly mutable pathogens must neutralize diverse strains. Developing effective immunization strategies to drive their evolution requires understanding how affinity maturation happens in an enviroment where variants of the same antigen are present. We present an in silico model of affinity maturation driven by antigen variants which reveals that induction of cross-reactive antibodies often occurs with low probability because conflicting selection forces, imposed by different antigen variants, can frustrate affinity maturation. We describe how variables such as temporal pattern of antigen administration influence the outcome of this frustrated evolutionary process. Our calculations predict, and experiments in mice with variant gp120 constructs of the HIV envelope protein confirm, that sequential immunization with antigen variants is preferred over a cocktail for induction of cross-reactive antibodies focused on the shared CD4 binding site epitope. PMID:25662010

  7. Hemoglobin fructation promotes heme degradation through the generation of endogenous reactive oxygen species

    NASA Astrophysics Data System (ADS)

    Goodarzi, M.; Moosavi-Movahedi, A. A.; Habibi-Rezaei, M.; Shourian, M.; Ghourchian, H.; Ahmad, F.; Farhadi, M.; Saboury, A. A.; Sheibani, N.

    2014-09-01

    Protein glycation is a cascade of nonenzymatic reactions between reducing sugars and amino groups of proteins. It is referred to as fructation when the reducing monosaccharide is fructose. Some potential mechanisms have been suggested for the generation of reactive oxygen species (ROS) by protein glycation reactions in the presence of glucose. In this state, glucose autoxidation, ketoamine, and oxidative advance glycation end products (AGEs) formation are considered as major sources of ROS and perhaps heme degradation during hemoglobin glycation. However, whether fructose mediated glycation produces ROS and heme degradation is unknown. Here we report that ROS (H2O2) production occurred during hemoglobin fructation in vitro using chemiluminescence methods. The enhanced heme exposure and degradation were determined using UV-Vis and fluorescence spectrophotometry. Following accumulation of ROS, heme degradation products were accumulated reaching a plateau along with the detected ROS. Thus, fructose may make a significant contribution to the production of ROS, glycation of proteins, and heme degradation during diabetes.

  8. High fluence laser irradiation induces reactive oxygen species generation in human lung adenocarcinoma cells

    NASA Astrophysics Data System (ADS)

    Wang, Fang; Xing, Da; Chen, Tong-Sheng

    2006-09-01

    Low-power laser irradiation (LPLI) has been used for therapies such as curing spinal cord injury, healing wound et al. Yet, the mechanism of LPLI remains unclear. Our previous study showed that low fluences laser irradiation induces human lung adenocarcinoma cells (ASTC-a-1) proliferation, but high fluences induced apoptosis and caspase-3 activation. In order to study the mechanism of apoptosis induced by high fluences LPLI further, we have measured the dynamics of generation of reactive oxygen species (ROS) using H IIDCFDA fluorescence probes during this process. ASTC-a-1 cells apoptosis was induced by He-Ne laser irradiation at high fluence of 120J/cm2. A confocal laser scanning microscope was used to perform fluorescence imaging. The results demonstrated that high fluence LPLI induced the increase of mitochondria ROS. Our studies contribute to clarify the biological mechanism of high fluence LPLI-induced cell apoptosis.

  9. Reactive oxygen species generated from skeletal muscles are required for gecko tail regeneration

    PubMed Central

    Zhang, Qing; Wang, Yingjie; Man, Lili; Zhu, Ziwen; Bai, Xue; Wei, Sumei; Liu, Yan; Liu, Mei; Wang, Xiaochuan; Gu, Xiaosong; Wang, Yongjun

    2016-01-01

    Reactive oxygen species (ROS) participate in various physiological and pathological functions following generation from different types of cells. Here we explore ROS functions on spontaneous tail regeneration using gecko model. ROS were mainly produced in the skeletal muscle after tail amputation, showing a temporal increase as the regeneration proceeded. Inhibition of the ROS production influenced the formation of autophagy in the skeletal muscles, and as a consequence, the length of the regenerating tail. Transcriptome analysis has shown that NADPH oxidase (NOX2) and the subunits (p40phox and p47phox) are involved in the ROS production. ROS promoted the formation of autophagy through regulation of both ULK and MAPK activities. Our results suggest that ROS produced by skeletal muscles are required for the successful gecko tail regeneration. PMID:26853930

  10. Reactive oxygen species generated from skeletal muscles are required for gecko tail regeneration.

    PubMed

    Zhang, Qing; Wang, Yingjie; Man, Lili; Zhu, Ziwen; Bai, Xue; Wei, Sumei; Liu, Yan; Liu, Mei; Wang, Xiaochuan; Gu, Xiaosong; Wang, Yongjun

    2016-02-08

    Reactive oxygen species (ROS) participate in various physiological and pathological functions following generation from different types of cells. Here we explore ROS functions on spontaneous tail regeneration using gecko model. ROS were mainly produced in the skeletal muscle after tail amputation, showing a temporal increase as the regeneration proceeded. Inhibition of the ROS production influenced the formation of autophagy in the skeletal muscles, and as a consequence, the length of the regenerating tail. Transcriptome analysis has shown that NADPH oxidase (NOX2) and the subunits (p40(phox) and p47(phox)) are involved in the ROS production. ROS promoted the formation of autophagy through regulation of both ULK and MAPK activities. Our results suggest that ROS produced by skeletal muscles are required for the successful gecko tail regeneration.

  11. Synergistic microglial reactive oxygen species generation induced by pesticides lindane and dieldrin.

    PubMed

    Mao, Haoyu; Liu, Bin

    2008-08-27

    Elevated environmental exposure to pesticides is a known risk factor to the development of sporadic Parkinson's disease resulting from the degeneration of nigral dopamine neurons. Among the suspected agents are the highly persistent and bioaccumulative organochlorinated pesticides (OCPs). We report here that lindane and dieldrin, two widely present OCPs that are found enriched in the nigra of postmortem Parkinson's disease brains synergistically induced the production of reactive oxygen species (ROS) in microglia. Inhibitor studies indicated that the lindane and dieldrin-induced ROS generation was mediated by NADPH oxidase. As microglial ROS is a key contributor to the degeneration of the oxidative damage-vulnerable dopamine neurons, our findings shed significant light on the role of OCPs in the development of Parkinson's disease.

  12. The antimicrobial activity of prototype modified honeys that generate reactive oxygen species (ROS) hydrogen peroxide.

    PubMed

    Cooke, Jonathan; Dryden, Matthew; Patton, Thomas; Brennan, James; Barrett, John

    2015-01-28

    Antimicrobial resistance continues to be a global issue in healthcare organisations. Honey has long been shown to possess wound healing and antimicrobial properties that are dependent on a number of physical and chemical properties of the honey. We tested the antimicrobial activity of a medicinal honey, Surgihoney® (SH) and two prototype modified honeys made by Apis mellifera (honeybee) against Staphylococcus aureus (NCIMB 9518). We also examined the modified honey prototypes for the ability to generate reactive oxygen species (ROS) by changing the level of production of hydrogen peroxide from the samples. Surgihoney® (SH) was compared with two modified honeys, Prototype 1 (PT1) and Prototype 2 (PT2) using a bioassay method against a standard strain of Staphylococcus aureus. Further work studied the rate of generation of ROS hydrogen peroxide from these preparations. Surgihoney® antimicrobial activity was shown to be largely due to ROS hydrogen peroxide production. By modification of Surgihoney®, two more potent honey prototypes were shown to generate between a two- and three-fold greater antibacterial activity and up to ten times greater ROS peroxide activity. Surgihoney® is a clinically available wound antiseptic dressing that shows good antimicrobial activity. Two further honey prototypes have been shown to have antimicrobial activity that is possible to be enhanced due to demonstrated increases in ROS peroxide activity.

  13. Plasma cell treatment device Plasma-on-Chip: Monitoring plasma-generated reactive species in microwells.

    PubMed

    Oh, Jun-Seok; Kojima, Shinya; Sasaki, Minoru; Hatta, Akimitsu; Kumagai, Shinya

    2017-02-08

    We have developed a plasma cell treatment device called Plasma-on-Chip that enables the real-time monitoring of a single cell culture during plasma treatment. The device consists of three parts: 1) microwells for cell culture, 2) a microplasma device for generating reactive oxygen and nitrogen species (RONS) for use in cell treatment, and 3) through-holes (microchannels) that connect each microwell with the microplasma region for RONS delivery. Here, we analysed the delivery of the RONS to the liquid culture medium stored in the microwells. We developed a simple experimental set-up using a microdevice and applied in situ ultraviolet absorption spectroscopy with high sensitivity for detecting RONS in liquid. The plasma-generated RONS were delivered into the liquid culture medium via the through-holes fabricated into the microdevice. The RONS concentrations were on the order of 10-100 μM depending on the size of the through-holes. In contrast, we found that the amount of dissolved oxygen was almost constant. To investigate the process of RONS generation, we numerically analysed the gas flow in the through-holes. We suggest that the circulating gas flow in the through-holes promotes the interaction between the plasma (ionised gas) and the liquid, resulting in enhanced RONS concentrations.

  14. Silver-ion-mediated reactive oxygen species generation affecting bactericidal activity.

    PubMed

    Park, Hee-Jin; Kim, Jee Yeon; Kim, Jaeeun; Lee, Joon-Hee; Hahn, Ji-Sook; Gu, Man Bock; Yoon, Jeyong

    2009-03-01

    Silver ions have been widely used as disinfectants that inhibit bacterial growth by inhibiting the essential enzymatic functions of the microorganism via interaction with the thiol-group of l-cysteine. However, silver-ion-mediated perturbation of the bacterial respiratory chain has raised the possibility of reactive oxygen species (ROS) generation. We used bacterial reporter strains specifically responding to superoxide radicals and found that silver-ion-mediated ROS-generation affected bactericidal activity. Almost half the log reduction in Escherichia coli and Staphylococcus aureus populations (model strains for gram negative and positive bacteria, respectively) caused by silver-ion disinfection was attributed to ROS-mediated bactericidal activity. The major form of ROS generated was the superoxide-radical; H(2)O(2) was not induced. Furthermore, silver ions strongly enhanced paraquat-induced oxidative stress, indicating close correlation and synergism between the conventional and ROS-mediated silver toxicity. Our results suggest that further studies in silver-based disinfection systems should consider the oxygen concentration and ROS reaction.

  15. Plasma cell treatment device Plasma-on-Chip: Monitoring plasma-generated reactive species in microwells

    NASA Astrophysics Data System (ADS)

    Oh, Jun-Seok; Kojima, Shinya; Sasaki, Minoru; Hatta, Akimitsu; Kumagai, Shinya

    2017-02-01

    We have developed a plasma cell treatment device called Plasma-on-Chip that enables the real-time monitoring of a single cell culture during plasma treatment. The device consists of three parts: 1) microwells for cell culture, 2) a microplasma device for generating reactive oxygen and nitrogen species (RONS) for use in cell treatment, and 3) through-holes (microchannels) that connect each microwell with the microplasma region for RONS delivery. Here, we analysed the delivery of the RONS to the liquid culture medium stored in the microwells. We developed a simple experimental set-up using a microdevice and applied in situ ultraviolet absorption spectroscopy with high sensitivity for detecting RONS in liquid. The plasma-generated RONS were delivered into the liquid culture medium via the through-holes fabricated into the microdevice. The RONS concentrations were on the order of 10-100 μM depending on the size of the through-holes. In contrast, we found that the amount of dissolved oxygen was almost constant. To investigate the process of RONS generation, we numerically analysed the gas flow in the through-holes. We suggest that the circulating gas flow in the through-holes promotes the interaction between the plasma (ionised gas) and the liquid, resulting in enhanced RONS concentrations.

  16. p53 activation contributes to patulin-induced nephrotoxicity via modulation of reactive oxygen species generation

    PubMed Central

    Jin, Huan; Yin, Shutao; Song, Xinhua; Zhang, Enxiang; Fan, Lihong; Hu, Hongbo

    2016-01-01

    Patulin is a major mycotoxin found in fungal contaminated fruits and their derivative products. Previous studies showed that patulin was able to induce increase of reactive oxygen species (ROS) generation and oxidative stress was suggested to play a pivotal role in patulin-induced multiple toxic signaling. The objective of the present study was to investigate the functional role of p53 in patulin-induced oxidative stress. Our study demonstrated that higher levels of ROS generation and DNA damage were induced in wild-type p53 cell lines than that found in either knockdown or knockout p53 cell lines in response to patulin exposure, suggesting p53 activation contributed to patulin-induced ROS generation. Mechanistically, we revealed that the pro-oxidant role of p53 in response to patulin was attributed to its ability to suppress catalase activity through up-regulation of PIG3. Moreover, these in vitro findings were further validated in the p53 wild-type/knockout mouse model. To the best of our knowledge, this is the first report addressing the functional role of p53 in patulin-induced oxidative stress. The findings of the present study provided novel insights into understanding mechanisms behind oxidative stress in response to patulin exposure. PMID:27071452

  17. Metal-dependent generation of reactive oxygen species from amyloid proteins implicated in neurodegenerative disease.

    PubMed

    Allsop, David; Mayes, Jennifer; Moore, Susan; Masad, Atef; Tabner, Brian J

    2008-12-01

    Using a method based on ESR spectroscopy and spin-trapping, we have shown that Abeta (amyloid beta-peptide) (implicated in Alzheimer's disease), alpha-synuclein (implicated in Parkinson's disease), ABri (British dementia peptide) (responsible for familial British dementia), certain toxic fragments of the prion protein (implicated in the transmissible spongiform encephalopathies) and the amylin peptide (found in the pancreas in Type 2 diabetes mellitus) all have the common ability to generate H(2)O(2) in vitro. Numerous controls (reverse, scrambled and non-toxic peptides) lacked this property. We have also noted a positive correlation between the ability of the various proteins tested to generate H(2)O(2) and their toxic effects on cultured cells. In the case of Abeta and ABri, we have shown that H(2)O(2) is generated as a short burst during the early stages of aggregation and is associated with the presence of protofibrils or oligomers, rather than mature fibrils. H(2)O(2) is readily converted into the aggressive hydroxyl radical by Fenton chemistry, and this extremely reactive radical could be responsible for much of the oxidative damage seen in all of the above disorders. We suggest that the formation of a redox-active complex involving the relevant amyloidogenic protein and certain transition-metal ions could play an important role in the pathogenesis of several different protein misfolding disorders.

  18. Targeting Cancer Cells with Reactive Oxygen and Nitrogen Species Generated by Atmospheric-Pressure Air Plasma

    PubMed Central

    Hoan, Nguyen Ngoc; Kim, Churl Ho; Moon, Eunpyo; Choi, Kyeong Sook; Yang, Sang Sik; Lee, Jong-Soo

    2014-01-01

    The plasma jet has been proposed as a novel therapeutic method for cancer. Anticancer activity of plasma has been reported to involve mitochondrial dysfunction. However, what constituents generated by plasma is linked to this anticancer process and its mechanism of action remain unclear. Here, we report that the therapeutic effects of air plasma result from generation of reactive oxygen/nitrogen species (ROS/RNS) including H2O2, Ox, OH−, •O2, NOx, leading to depolarization of mitochondrial membrane potential and mitochondrial ROS accumulation. Simultaneously, ROS/RNS activate c-Jun NH2-terminal kinase (JNK) and p38 kinase. As a consequence, treatment with air plasma jets induces apoptotic death in human cervical cancer HeLa cells. Pretreatment of the cells with antioxidants, JNK and p38 inhibitors, or JNK and p38 siRNA abrogates the depolarization of mitochondrial membrane potential and impairs the air plasma-induced apoptotic cell death, suggesting that the ROS/RNS generated by plasma trigger signaling pathways involving JNK and p38 and promote mitochondrial perturbation, leading to apoptosis. Therefore, administration of air plasma may be a feasible strategy to eliminate cancer cells. PMID:24465942

  19. Plasma cell treatment device Plasma-on-Chip: Monitoring plasma-generated reactive species in microwells

    PubMed Central

    Oh, Jun-Seok; Kojima, Shinya; Sasaki, Minoru; Hatta, Akimitsu; Kumagai, Shinya

    2017-01-01

    We have developed a plasma cell treatment device called Plasma-on-Chip that enables the real-time monitoring of a single cell culture during plasma treatment. The device consists of three parts: 1) microwells for cell culture, 2) a microplasma device for generating reactive oxygen and nitrogen species (RONS) for use in cell treatment, and 3) through-holes (microchannels) that connect each microwell with the microplasma region for RONS delivery. Here, we analysed the delivery of the RONS to the liquid culture medium stored in the microwells. We developed a simple experimental set-up using a microdevice and applied in situ ultraviolet absorption spectroscopy with high sensitivity for detecting RONS in liquid. The plasma-generated RONS were delivered into the liquid culture medium via the through-holes fabricated into the microdevice. The RONS concentrations were on the order of 10–100 μM depending on the size of the through-holes. In contrast, we found that the amount of dissolved oxygen was almost constant. To investigate the process of RONS generation, we numerically analysed the gas flow in the through-holes. We suggest that the circulating gas flow in the through-holes promotes the interaction between the plasma (ionised gas) and the liquid, resulting in enhanced RONS concentrations. PMID:28176800

  20. Calcium-induced generation of reactive oxygen species in brain mitochondria is mediated by permeability transition.

    PubMed

    Hansson, Magnus J; Månsson, Roland; Morota, Saori; Uchino, Hiroyuki; Kallur, Thérese; Sumi, Tetsuo; Ishii, Nagao; Shimazu, Motohide; Keep, Marcus F; Jegorov, Alexandr; Elmér, Eskil

    2008-08-01

    Mitochondrial uptake of calcium in excitotoxicity is associated with subsequent increase in reactive oxygen species (ROS) generation and delayed cellular calcium deregulation in ischemic and neurodegenerative insults. The mechanisms linking mitochondrial calcium uptake and ROS production remain unknown but activation of the mitochondrial permeability transition (mPT) may be one such mechanism. In the present study, calcium increased ROS generation in isolated rodent brain and human liver mitochondria undergoing mPT despite an associated loss of membrane potential, NADH and respiration. Unspecific permeabilization of the inner mitochondrial membrane by alamethicin likewise increased ROS independently of calcium, and the ROS increase was further potentiated if NAD(H) was added to the system. Importantly, calcium per se did not induce a ROS increase unless mPT was triggered. Twenty-one cyclosporin A analogs were evaluated for inhibition of calcium-induced ROS and their efficacy clearly paralleled their potency of inhibiting mPT-mediated mitochondrial swelling. We conclude that while intact respiring mitochondria possess powerful antioxidant capability, mPT induces a dysregulated oxidative state with loss of GSH- and NADPH-dependent ROS detoxification. We propose that mPT is a significant cause of pathological ROS generation in excitotoxic cell death.

  1. Targeting cancer cells with reactive oxygen and nitrogen species generated by atmospheric-pressure air plasma.

    PubMed

    Ahn, Hak Jun; Kim, Kang Il; Hoan, Nguyen Ngoc; Kim, Churl Ho; Moon, Eunpyo; Choi, Kyeong Sook; Yang, Sang Sik; Lee, Jong-Soo

    2014-01-01

    The plasma jet has been proposed as a novel therapeutic method for cancer. Anticancer activity of plasma has been reported to involve mitochondrial dysfunction. However, what constituents generated by plasma is linked to this anticancer process and its mechanism of action remain unclear. Here, we report that the therapeutic effects of air plasma result from generation of reactive oxygen/nitrogen species (ROS/RNS) including H2O2, Ox, OH-, •O2, NOx, leading to depolarization of mitochondrial membrane potential and mitochondrial ROS accumulation. Simultaneously, ROS/RNS activate c-Jun NH2-terminal kinase (JNK) and p38 kinase. As a consequence, treatment with air plasma jets induces apoptotic death in human cervical cancer HeLa cells. Pretreatment of the cells with antioxidants, JNK and p38 inhibitors, or JNK and p38 siRNA abrogates the depolarization of mitochondrial membrane potential and impairs the air plasma-induced apoptotic cell death, suggesting that the ROS/RNS generated by plasma trigger signaling pathways involving JNK and p38 and promote mitochondrial perturbation, leading to apoptosis. Therefore, administration of air plasma may be a feasible strategy to eliminate cancer cells.

  2. Targeting and Regulation of Reactive Oxygen Species Generation by Nox Family NADPH Oxidases

    PubMed Central

    Morand, Stanislas; Hurt, Darrell; Ueyama, Takehiko

    2009-01-01

    Abstract Nox family NADPH oxidases serve a variety of functions requiring reactive oxygen species (ROS) generation, including antimicrobial defense, biosynthetic processes, oxygen sensing, and redox-based cellular signaling. We explored targeting, assembly, and activation of several Nox family oxidases, since ROS production appears to be regulated both spatially and temporally. Nox1 and Nox3 are similar to the phagocytic (Nox2-based) oxidase, functioning as multicomponent superoxide-generating enzymes. Factors regulating their activities include cytosolic activator and organizer proteins and GTP-Rac. Their regulation varies, with the following rank order: Nox2 > Nox1 > Nox3. Determinants of subcellular targeting include: (a) formation of Nox-p22phox heterodimeric complexes allowing plasma membrane translocation, (b) phospholipids-binding specificities of PX domain-containing organizer proteins (p47phox or Nox organizer 1 (Noxo1 and p40phox), and (c) variably splicing of Noxo1 PX domains directing them to nuclear or plasma membranes. Dual oxidases (Duox1 and Duox2) are targeted by different mechanisms. Plasma membrane targeting results in H2O2 release, not superoxide, to support extracellular peroxidases. Human Duox1 and Duox2 have no demonstrable peroxidase activity, despite their extensive homology with heme peroxidases. The dual oxidases were reconstituted by Duox activator 2 (Duoxa2) or two Duoxa1 variants, which dictate maturation, subcellular localization, and the type of ROS generated by forming stable complexes with Duox. Antioxid Redox Signal. 11, 2607–2619. PMID:19438290

  3. Sepsis increases contraction-related generation of reactive oxygen species in the diaphragm.

    PubMed

    Nethery, D; DiMarco, A; Stofan, D; Supinski, G

    1999-10-01

    Recent work indicates that free radicals mediate sepsis-induced diaphragmatic dysfunction. These previous experiments have not, however, established the source of the responsible free radical species. In theory, this phenomenon could be explained if one postulates that sepsis elicits an upregulation of contraction-related free radical formation in muscle. The purpose of the present study was to test this hypothesis by examination of the effect of sepsis on contraction-related free radical generation [i.e. , formation of reactive oxygen species (ROS)] by the diaphragm. Rats were killed 18 h after injection with either saline or endotoxin. In vitro hemidiaphragms were then prepared, and ROS generation during electrically induced contractions (20-Hz trains delivered for 10 min) was assessed by measurement of the conversion of hydroethidine to ethidium. ROS generation was negligible in noncontracting diaphragms from both saline- and endotoxin-treated groups (2.0 +/- 0. 6 and 2.8 +/- 1.0 ng ethidium/mg tissue, respectively), but it was marked in contracting diaphragms from saline-treated animals (19.0 +/- 2.8 ng/mg tissue) and even more pronounced (30.0 +/- 2.8 ng/mg tissue) in diaphragms from septic animals (P < 0.01). This enhanced free radical generation occurred despite the fact that the force-time integral (i.e., the area under the curve of force vs. time) for control diaphragms was higher than that for the septic group. In additional studies, in which we altered the stimulation paradigm in control muscles to achieve a force-time integral similar to that achieved in septic muscles, an even greater difference between control and septic muscle ROS formation was observed. These data indicate that ROS formation during contraction is markedly enhanced in diaphragms from endotoxin-treated septic animals. We speculate that ROS generated in this fashion plays a central role in producing sepsis-related skeletal muscle dysfunction.

  4. Protective role of carbon dioxide (CO2) in generation of reactive oxygen species.

    PubMed

    Bolevich, Sergey; Kogan, Alekandr Haritonovic; Zivkovic, Vladimir; Djuric, Dusan; Novikov, Aleksey Aleksejevic; Vorobyev, Sergey Ivanovic; Jakovljevic, Vladimir

    2016-01-01

    The results testify to the fact that CO2 is a powerful inhibitor of reactive oxygen species (ROS) generation by cells (blood phagocytes and alveolar macrophages of 96 people and cells of inner organs and tissue phagocytes (of liver, brain, myocardium, lungs, kidneys, stomach, and skeleton muscles), as well as by mitochondria of the liver of 186 white mice and human tissues. Generation of ROS was determined using various methods with CO2 directly acting on the cells and bioptates and indirectly on the organism as a whole. CO2 in the concentration of 5.1% (P = 37.5 mmHg), 8.2% (P = 60.0 mmHg), and 20% (P = 146.0 mmHg) in a mixture with air (total pressure = 730 mmHg) inhibits the basal ROS generation by phagocytes on the average by 3.52, 5.69, and 10.03 times, respectively (p < 0.05), and the stimulated by corpuscular particles: (a) zymosan by 3.24, 4.43, and 7.95 times; (b)SiO2: by 2.99, 3.24, and 5.76 times (p < 0.05). This is confirmed by the feet that CO2, along with inhibiting the O2 (-) generation by cells of the various organs, including the liver, as a rule, by 2.19-4.7 times, p < 0.01 or <0.001 induces simultaneously a decrease in the O2 (-) generation by mitochondria isolated from the liver (by 1.91-3.2 times, p < 0.001). The mechanism of CO2 influence is realized, in part, by inhibition of NADPH-oxidase activity. Taken into consideration proven role of CO2 in different pathophysiological conditions, (such as endoarteritis, bronchial asthma, and infectious diseases), present findings may be of clinical interest in terms of potential implementation of CO2 donors as adjuvant therapeutics in these diseases.

  5. Surface functionalization of titanium dioxide nanoparticles: Photo-stability and reactive oxygen species (ROS) generation

    NASA Astrophysics Data System (ADS)

    Louis, Kacie M.

    Metal oxide nanoparticles are becoming increasingly prevalent in society for applications of sunscreens, cosmetics, paints, biomedical imaging, and photovoltaics. Due to the increased surface area to volume ratio of nanoparticles compared to bulk materials, it is important to know the health and safety impacts of these materials. One mechanism of toxicity of nominally "safe" materials such as TiO 2 is through the photocatalytic generation of reactive oxygen species (ROS). ROS production and ligand degradation can affect the bioavailability of these particles in aqueous organisms. We have investigated ROS generation by functionalized TiO2 nanoparticles and its influence on aggregation and bioavailability and toxicity to zebrafish embryos/larvae. For these studies we investigated anatase TiO2 nanoparticles. For application purposes and solution stability, the TiO2 nanoparticles were functionalized with a variety of ligands such as citrate, 3,4-dihydroxybenzaldehyde, and ascorbate. We quantitatively examined the amount of ROS produced in aqueous solution using fluorescent probes and see that more ROS is produced under UV light than in the dark control. Our measurements show that TiO2 toxicity reaches a maximum for nanoparticles with smaller diameters, and is correlated with surface area dependent changes in ROS generation. In an effort to reduce toxicity through control of the surface and surface ligands, we synthesized anatase nanoparticles of different sizes, functionalized them with different ligands, and examined the resulting ROS generation and ligand stability. Using a modular ligand containing a hydrophobic inner region and a hydrophilic outer region, we synthesized water-stable nanoparticles, via two different chemical reactions, having much-reduced ROS generation and thus reduced toxicity. These results suggest new strategies for making safer nanoparticles while still retaining their desired properties. We also examine the degradation of the different ligands

  6. 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

  7. Evaluation of Sulfatase-Directed Quinone Methide Traps for Proteomics

    PubMed Central

    Lenger, Janina; Schröder, Marius; Ennemann, Eva; Müller, Benjamin; Wong, Chi-Huey; Noll, Thomas; Dierks, Thomas; Hanson, Sarah R.; Sewald, Norbert

    2012-01-01

    Sulfatases hydrolytically cleave sulfate esters through a unique catalytic aldehyde, which is introduced by a posttranslational oxidation. To profile active sulfatases in health and disease, activity-based proteomic tools are needed. Herein, quinone methide (QM) traps directed against sulfatases are evaluated as activity-based proteomic probes (ABPPs). Starting from a p-fluoromethylphenyl sulfate scaffold, enzymatically generated QM traps can inactivate bacterial aryl sulfatases from Pseudomonas aeruginosa and Klebsiella pneumonia and human steroid sulfatase. However, multiple enzyme-generated QMs form, diffuse, and non-specifically label purified enzyme. In complex proteomes, QM labelling is sulfatase-dependent but also non-specific. Thus, fluoromethylphenyl sulfates are poor ABPPs for sulfatases. PMID:21570853

  8. Isoprenoid quinones and fatty acids of Zoogloea.

    PubMed

    Hiraishi, A; Shin, Y K; Sugiyama, J; Komagata, K

    1992-04-01

    Nine Zoogloea strains including the type strain of Z. ramigera (IAM 12136 = ATCC 19544 = N.C. Dondero 106) and newly isolated strains were investigated for isoprenoid quinone composition and whole-cell fatty acid profiles. Seven of the tested strains, having phenotypic properties typical of Zoogloea, were characterized by their production of both ubiquinone-8 and rhodoquinone-8 as major quinones, whereas the remaining two strains, Z. ramigera IAM 12669 (= K. Crabtree I-16-M) and IAM 12670 (= P.R. Dugan 115), formed ubiquinone-10 and ubiquinone-8, respectively, as the sole quinone. All rhodoquinone-producing strains contained palmitoleic acid and 3-hydroxy-decanoic acid as the major components of nonpolar and hydroxylated fatty acids, respectively. Marked differences were noted in the fatty acid composition between the strains with and without rhodoquinones. The chemotaxonomic data suggested that the rhodoquinone-lacking strains should be excluded from the genus Zoogloea. Since there have been no reliable taxonomic tools for Zoogloea, rhodoquinone analysis may provide a new criterion of great promise for identifying Zoogloea strains.

  9. Studies using structural analogs and inbred strain differences to support a role for quinone methide metabolites of butylated hydroxytoluene (BHT) in mouse lung tumor promotion.

    PubMed

    Thompson, J A; Carlson, T J; Sun, Y; Dwyer-Nield, L D; Malkinson, A M

    2001-03-07

    Chronic treatment of BALB and GRS mice with BHT (2,6-di-tert-butyl-4-methylphenol) following a single urethane injection increases lung tumor multiplicity, but this does not occur in CXB4 mice. Previous data suggest that promotion requires the conversion of BHT to a tert-butyl-hydroxylated metabolite (BHTOH) in lung and the subsequent oxidation of this species to an electrophilic quinone methide. To obtain additional evidence for the importance of quinone methide formation, structural analogs that form less reactive quinone methides were tested and found to lack promoting activity in BHT-responsive mice. The possibility that promotion-unresponsive strains are unable to form BHTOH was tested by substituting this compound for BHT in the promotion protocol using CXB4 mice. No promotion occurred, and in-vitro work demonstrated that CXB4 mice are, in fact, capable of producing BHTOH and its quinone methide, albeit in smaller quantities. Incubations with BALB lung microsomes and radiolabeled substrates confirmed that more covalent binding to protein occurs with BHTOH than with BHT and, in addition, BHTOH quinone methide is considerably more toxic to mouse lung epithelial cells than BHT quinone methide. These data are consistent with the hypothesis that a two-step oxidation process, i.e. hydroxylation and quinone methide formation, is required for the promotion of mouse lung tumors by BHT.

  10. Biological reactive intermediates (BRIs) formed from botanical dietary supplements.

    PubMed

    Dietz, Birgit M; Bolton, Judy L

    2011-06-30

    The use of botanical dietary supplements is increasingly popular, due to their natural origin and the perceived assumption that they are safer than prescription drugs. While most botanical dietary supplements can be considered safe, a few contain compounds, which can be converted to biological reactive intermediates (BRIs) causing toxicity. For example, sassafras oil contains safrole, which can be converted to a reactive carbocation forming genotoxic DNA adducts. Alternatively, some botanical dietary supplements contain stable BRIs such as simple Michael acceptors that react with chemosensor proteins such as Keap1 resulting in induction of protective detoxification enzymes. Examples include curcumin from turmeric, xanthohumol from hops, and Z-ligustilide from dang gui. Quinones (sassafras, kava, black cohosh), quinone methides (sassafras), and epoxides (pennyroyal oil) represent BRIs of intermediate reactivity, which could generate both genotoxic and/or chemopreventive effects. The biological targets of BRIs formed from botanical dietary supplements and their resulting toxic and/or chemopreventive effects are closely linked to the reactivity of BRIs as well as dose and time of exposure. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

  11. Cytotoxicity and reactive oxygen species generation from aggregated carbon and carbonaceous nanoparticulate materials.

    PubMed

    Garza, Kristine M; Soto, Karla F; Murr, Lawrence E

    2008-01-01

    We have investigated the cytotoxicity and reactive oxygen species (ROS) generation for indoor and outdoor soots: candle, wood, diesel, tire, and natural gas burner soots--along with surrogate black carbon, various multiwall carbon nanotube aggregate materials, TiO2 (anatase) and chrysotile asbestos as reference materials. All soots were observed utilizing TEM and FESEM to be composed of aggregated, primary spherules (20-80 nm diameter) forming complex, branched fractal structures. These spherules were composed of intercalated, turbostratic arrangements of curved graphene fragments with varying concentrations ofpolycyclic aromatic hydrocarbon (PAH) isomers. In vitro cultures with an immortalized human lung epithelial carcinoma cell line (A549) treated with these materials showed decreased cell viability and variations in ROS production, with no correlations to PAH content. The data demonstrate that soots are cytotoxic and that cytotoxicity is not related to PAH content but is related to ROS generation, suggesting that soot induces cellular oxidative stress and that cell viability assays can be indicators of ROS production.

  12. Rapid hydrogen gas generation using reactive thermal decomposition of uranium hydride.

    SciTech Connect

    Kanouff, Michael P.; Van Blarigan, Peter; Robinson, David B.; Shugard, Andrew D.; Gharagozloo, Patricia E.; Buffleben, George M.; James, Scott Carlton; Mills, Bernice E.

    2011-09-01

    Oxygen gas injection has been studied as one method for rapidly generating hydrogen gas from a uranium hydride storage system. Small scale reactors, 2.9 g UH{sub 3}, were used to study the process experimentally. Complimentary numerical simulations were used to better characterize and understand the strongly coupled chemical and thermal transport processes controlling hydrogen gas liberation. The results indicate that UH{sub 3} and O{sub 2} are sufficiently reactive to enable a well designed system to release gram quantities of hydrogen in {approx} 2 seconds over a broad temperature range. The major system-design challenge appears to be heat management. In addition to the oxidation tests, H/D isotope exchange experiments were performed. The rate limiting step in the overall gas-to-particle exchange process was found to be hydrogen diffusion in the {approx}0.5 {mu}m hydride particles. The experiments generated a set of high quality experimental data; from which effective intra-particle diffusion coefficients can be inferred.

  13. Environmentally Persistent Free Radicals (EPFRs). 1. Generation of Reactive Oxygen Species in Aqueous Solutions

    PubMed Central

    Khachatryan, Lavrent; Vejerano, Eric; Lomnicki, Slawo; Dellinger, Barry

    2011-01-01

    Reactive oxygen species (ROS) generated by environmentally persistent free radicals (EPFRs) of 2-monochlorophenol, associated with CuO/silica particles, were detected using the chemical spin trap, 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), in conjunction with Electron Paramagnetic Resonance (EPR) spectroscopy. Yields of hydroxyl radical (.OH), superoxide anion radical (O2.−), and hydrogen peroxide (H2O2) generated by EPFR-particle systems are reported. Failure to trap superoxide radicals in aqueous solvent, formed from the reaction of EPFRs with molecular oxygen, results from the fast transformation of the superoxide to hydrogen peroxide. However, formation of superoxide as an intermediate product in hydroxyl radical formation in aprotic solutions of dimethyl sulfoxide (DMSO) and acetonitrile (AcN) was observed. Experiments with superoxide dismutase (SOD) and catalase (CAT) confirmed the formation of superoxide and hydrogen peroxide, respectively, in the presence of EPFRs. The large number of hydroxyl radicals formed per EPFR and monotonic increase of the DMPO-OH spin adduct concentration with the incubation time suggest a catalytic cycle of ROS formation. PMID:21823585

  14. Generation of reactive oxygen species from porous silicon microparticles in cell culture medium.

    PubMed

    Low, Suet Peng; Williams, Keryn A; Canham, Leigh T; Voelcker, Nicolas H

    2010-06-01

    Nanostructured (porous) silicon is a promising biodegradable biomaterial, which is being intensively researched as a tissue engineering scaffold and drug-delivery vehicle. Here, we tested the biocompatibility of non-treated and thermally-oxidized porous silicon particles using an indirect cell viability assay. Initial direct cell culture on porous silicon determined that human lens epithelial cells only poorly adhered to non-treated porous silicon. Using an indirect cell culture assay, we found that non-treated microparticles caused complete cell death, indicating that these particles generated a toxic product in cell culture medium. In contrast, thermally-oxidized microparticles did not reduce cell viability significantly. We found evidence for the generation of reactive oxygen species (ROS) by means of the fluorescent probe 2',7'-dichlorofluorescin. Our results suggest that non-treated porous silicon microparticles produced ROS, which interacted with the components of the cell culture medium, leading to the formation of cytotoxic species. Oxidation of porous silicon microparticles not only mitigated, but also abolished the toxic effects.

  15. Enterovirus 71 Induces Mitochondrial Reactive Oxygen Species Generation That is Required for Efficient Replication

    PubMed Central

    Cheng, Mei-Ling; Weng, Shiue-Fen; Kuo, Chih-Hao; Ho, Hung-Yao

    2014-01-01

    Redox homeostasis is an important host factor determining the outcome of infectious disease. Enterovirus 71 (EV71) infection has become an important endemic disease in Southeast Asia and China. We have previously shown that oxidative stress promotes viral replication, and progeny virus induces oxidative stress in host cells. The detailed mechanism for reactive oxygen species (ROS) generation in infected cells remains elusive. In the current study, we demonstrate that mitochondria were a major ROS source in EV71-infected cells. Mitochondria in productively infected cells underwent morphologic changes and exhibited functional anomalies, such as a decrease in mitochondrial electrochemical potential ΔΨm and an increase in oligomycin-insensitive oxygen consumption. Respiratory control ratio of mitochondria from infected cells was significantly lower than that of normal cells. The total adenine nucleotide pool and ATP content of EV71-infected cells significantly diminished. However, there appeared to be a compensatory increase in mitochondrial mass. Treatment with mito-TEMPO reduced eIF2α phosphorylation and viral replication, suggesting that mitochondrial ROS act to promote viral replication. It is plausible that EV71 infection induces mitochondrial ROS generation, which is essential to viral replication, at the sacrifice of efficient energy production, and that infected cells up-regulate biogenesis of mitochondria to compensate for their functional defect. PMID:25401329

  16. Generation of Reactive Oxygen Species via NOXa Is Important for Development and Pathogenicity of Mycosphaerella graminicola

    PubMed Central

    Choi, Yoon-E; Lee, Changsu

    2016-01-01

    The ascomycete fungus Mycosphaerella graminicola (synonym Zymoseptoria tritici) is an important pathogen of wheat causing economically significant losses. The primary nutritional mode of this fungus is thought to be hemibiotrophic. This pathogenic lifestyle is associated with an early biotrophic stage of nutrient uptake followed by a necrotrophic stage aided possibly by production of a toxin or reactive oxygen species (ROS). In many other fungi, the genes CREA and AREA are important during the biotrophic stage of infection, while the NOXa gene product is important during necrotrophic growth. To test the hypothesis that these genes are important for pathogenicity of M. graminicola, we employed an over-expression strategy for the selected target genes CREA, AREA, and NOXa, which might function as regulators of nutrient acquisition or ROS generation. Increased expressions of CREA, AREA, and NOXa in M. graminicola were confirmed via quantitative real-time PCR and strains were subsequently assayed for pathogenicity. Among them, the NOXa over-expression strain, NO2, resulted in significantly increased virulence. Moreover, instead of the usual filamentous growth, we observed a predominance of yeast-like growth of NO2 which was correlated with ROS production. Our data indicate that ROS generation via NOXa is important to pathogenicity as well as development in M. graminicola. PMID:27103853

  17. NAD(P)H-dependent quinone oxidoreductase 1 (NQO1) and cytochrome P450 oxidoreductase (CYP450OR) differentially regulate menadione-mediated alterations in redox status, survival and metabolism in pancreatic β-cells.

    PubMed

    Gray, Joshua P; Karandrea, Shpetim; Burgos, Delaine Zayasbazan; Jaiswal, Anil A; Heart, Emma A

    2016-11-16

    NQO1 (NAD(P)H-quinone oxidoreductase 1) reduces quinones and xenobiotics to less-reactive compounds via 2-electron reduction, one feature responsible for the role of NQO1 in antioxidant defense in several tissues. In contrast, NADPH cytochrome P450 oxidoreductase (CYP450OR), catalyzes the 1-electron reduction of quinones and xenobiotics, resulting in enhanced superoxide formation. However, to date, the roles of NQO1 and CYP450OR in pancreatic β-cell metabolism under basal conditions and oxidant challenge have not been characterized. Using NQO1 inhibition, over-expression and knock out, we have demonstrated that, in addition to protection of β-cells from toxic concentrations of the redox cycling quinone menadione, NQO1 also regulates the basal level of reduced-to-oxidized nucleotides, suggesting other role(s) beside that of an antioxidant enzyme. In contrast, over-expression of NADPH cytochrome P450 oxidoreductase (CYP450OR) resulted in enhanced redox cycling activity and decreased cellular viability, consistent with the enhanced generation of superoxide and H2O2. Basal expression of NQO1 and CYP450OR was comparable in isolated islets and liver. However, NQO1, but not CYP450OR, was strongly induced in β-cells exposed to menadione. NQO1 and CYP450OR exhibited a reciprocal preference for reducing equivalents in β-cells: while CYP450OR preferentially utilized NADPH, NQO1 primarily utilized NADH. Together, these results demonstrate that NQO1 and CYP450OR reciprocally regulate oxidant metabolism in pancreatic β-cells.

  18. Measuring protection of aromatic wine thiols from oxidation by competitive reactions vs wine preservatives with ortho-quinones.

    PubMed

    Nikolantonaki, Maria; Magiatis, Prokopios; Waterhouse, Andrew L

    2014-11-15

    Quinones are central intermediates in wine oxidation that can degrade the quality of wine by reactions with varietal thiols, such as 3-sulfanylhexanol, decreasing desirable aroma. Protection by wine preservatives (sulphur dioxide, glutathione, ascorbic acid and model tannin, phloroglucinol) was assessed by competitive sacrificial reactions with 4-methyl-1,2-benzoquinone, quantifying products and ratios by HPLC-UV-MS. Regioselectivity was assessed by product isolation and identification by NMR spectroscopy. Nucleophilic addition reactions compete with two electron reduction of quinones by sulphur dioxide or ascorbic acid, and both routes serve as effective quenching pathways, but minor secondary products from coupled redox reactions between the products and reactants are also observed. The wine preservatives were all highly reactive and thus all very protective against 3-sulfanylhexanol loss to the quinone, but showed only additive antioxidant effects. Confirmation of these reaction rates and pathways in wine is needed to assess the actual protective action of each tested preservative.

  19. Mechanism of enhanced removal of quinonic intermediates during electrochemical oxidation of Orange II under ultraviolet irradiation.

    PubMed

    Li, Fazhan; Li, Guoting; Zhang, Xiwang

    2014-03-01

    The effect of ultraviolet irradiation on generation of radicals and formation of intermediates was investigated in electrochemical oxidation of the azo-dye Orange II using a TiO2-modified β-PbO2 electrode. It was found that a characteristic absorbance of quinonic compounds at 255 nm, which is responsible for the rate-determining step during aromatics degradation, was formed only in electrocatalytic oxidation. The dye can be oxidized by either HO radicals or direct electron transfer. Quinonic compounds were produced concurrently. The removal of TOC by photo-assisted electrocatalytic oxidation was 1.56 times that of the sum of the other two processes, indicating a significant synergetic effect. In addition, once the ultraviolet irradiation was introduced into the process of electrocatalytic oxidation, the degradation rate of quinonic compounds was enhanced by as much as a factor of two. The more efficient generation of HO radicals resulted from the introduction of ultraviolet irradiation in electrocatalytic oxidation led to the significant synergetic effect as well as the inhibiting effect on the accumulation of quinonic compounds.

  20. Quinone-dependent proton transfer pathways in the photosynthetic cytochrome b6f complex.

    PubMed

    Hasan, S Saif; Yamashita, Eiki; Baniulis, Danas; Cramer, William A

    2013-03-12

    As much as two-thirds of the proton gradient used for transmembrane free energy storage in oxygenic photosynthesis is generated by the cytochrome b6f complex. The proton uptake pathway from the electrochemically negative (n) aqueous phase to the n-side quinone binding site of the complex, and a probable route for proton exit to the positive phase resulting from quinol oxidation, are defined in a 2.70-Å crystal structure and in structures with quinone analog inhibitors at 3.07 Å (tridecyl-stigmatellin) and 3.25-Å (2-nonyl-4-hydroxyquinoline N-oxide) resolution. The simplest n-side proton pathway extends from the aqueous phase via Asp20 and Arg207 (cytochrome b6 subunit) to quinone bound axially to heme c(n). On the positive side, the heme-proximal Glu78 (subunit IV), which accepts protons from plastosemiquinone, defines a route for H(+) transfer to the aqueous phase. These pathways provide a structure-based description of the quinone-mediated proton transfer responsible for generation of the transmembrane electrochemical potential gradient in oxygenic photosynthesis.

  1. Quinone-dependent proton transfer pathways in the photosynthetic cytochrome b6f complex

    PubMed Central

    Hasan, S. Saif; Yamashita, Eiki; Baniulis, Danas; Cramer, William A.

    2013-01-01

    As much as two-thirds of the proton gradient used for transmembrane free energy storage in oxygenic photosynthesis is generated by the cytochrome b6f complex. The proton uptake pathway from the electrochemically negative (n) aqueous phase to the n-side quinone binding site of the complex, and a probable route for proton exit to the positive phase resulting from quinol oxidation, are defined in a 2.70-Å crystal structure and in structures with quinone analog inhibitors at 3.07 Å (tridecyl-stigmatellin) and 3.25-Å (2-nonyl-4-hydroxyquinoline N-oxide) resolution. The simplest n-side proton pathway extends from the aqueous phase via Asp20 and Arg207 (cytochrome b6 subunit) to quinone bound axially to heme cn. On the positive side, the heme-proximal Glu78 (subunit IV), which accepts protons from plastosemiquinone, defines a route for H+ transfer to the aqueous phase. These pathways provide a structure-based description of the quinone-mediated proton transfer responsible for generation of the transmembrane electrochemical potential gradient in oxygenic photosynthesis. PMID:23440205

  2. LC-MS method for screening unknown microbial carotenoids and isoprenoid quinones.

    PubMed

    Kaiser, Philipp; Geyer, Roland; Surmann, Peter; Fuhrmann, Herbert

    2012-01-01

    The structure of secondary metabolites from microorganisms provides a useful tool for microbial characterization and chemotaxonomic classification. Microbial isoprenoid quinones, for example, are well described and used to distinguish among photosynthetic microorganism groups. In addition, isoprenoid quinones can also be found, together with carotenoids, in non-photosynthetic microorganisms. The aim of the present study was to develop a LC-MS/MS method which can analyze and identify these microbial isoprenoids. Positive atmospheric pressure chemical ionization (APCI) together with collisionally induced dissociation was applied for generation of informative fragment spectra by mass spectrometry. Enhanced product ion (EPI) scan in a linear ion trap with information dependent data acquisition (IDA) enabled generation of MS fragment data even from minor isoprenoids. The developed liquid chromatography method enabled separation of isoprenoid patterns from their ester derivatives. Discovery and structural characterization of isoprenoid quinones and carotenoids were carried out by comparing characteristics of fragment spectra from unknown compounds with fragment spectra of a range of isoprenoid standard compounds and using published data. Throughout the study 17 microorganisms (e.g., Acremonium butyri, Arthrobacter spp., Brevibacterium linens, Bullera variabilis, Exophiala dermatitidis, Lecythophora hoffmannii, Panthoea agglomerans, Rhodotorula spp., Xanthophyllomyces dendrorhous) were screened and probable structures of isoprenoid quinones and carotenoids were suggested. The method lays some foundations on the analysis of yet unknown isoprenoids in microorganisms by using LCMS/MS techniques.

  3. Substituent effects on carbocation stability: the pK(R) for p-quinone methide.

    PubMed

    Toteva, Maria M; Moran, Michael; Amyes, Tina L; Richard, John P

    2003-07-23

    A value of k(H) = 1.5 x 10(-)(3) M(-)(1) s(-)(1) has been determined for the generation of simple p-quinone methide by the acid-catalyzed cleavage of 4-hydroxybenzyl alcohol in water at 25 degrees C and I = 1.0 (NaClO(4)). This was combined with k(s) = 5.8 x 10(6) s(-)(1) for the reverse addition of solvent water to the 4-hydroxybenzyl carbocation [J. Am. Chem. Soc. 2002, 124, 6349-6356] to give pK(R) = -9.6 as the Lewis acidity constant of O-protonated p-quinone methide. Values of pK(R) = 2.3 for the Lewis acidity constant of neutral p-quinone methide and pK(add) = -7.6 for the overall addition of solvent water to p-quinone methide to form 4-hydroxybenzyl alcohol are also reported. The thermodynamic driving force for transfer of the elements of water from formaldehyde hydrate to p-quinone methide to form formaldehyde and p-(hydroxymethyl)phenol (4-hydroxybenzyl alcohol) is determined as 6 kcal/mol. This relatively small driving force represents the balance between the much stronger chemical bonds to oxygen at the reactant formaldehyde hydrate than at the product p-(hydroxymethyl)phenol and the large stabilization of product arising from the aromatization that accompanies solvent addition to p-quinone methide. The Marcus intrinsic barrier for nucleophilic addition of solvent water to the "extended" carbonyl group at p-quinone methide is estimated to be 4.5 kcal/mol larger than that for the addition of water to the simple carbonyl group of formaldehyde. O-Alkylation of p-quinone methide to give the 4-methoxybenzyl carbocation and of formaldehyde to give a simple oxocarbenium ion results in very little change in the relative Marcus intrinsic barriers for the addition of solvent water to these electrophiles.

  4. Mitochondrial reactive oxygen species generation and calcium increase induced by visible light in astrocytes.

    PubMed

    Jou, Mei-Jie; Jou, Shuo-Bin; Guo, Mei-Jin; Wu, Hong-Yueh; Peng, Tsung-I

    2004-04-01

    Mitochondria contain photosensitive chromophores that can be activated or inhibited by light in the visible range. Rather than utilizing light energy, however, mitochondrial electron transport oxidation-reduction reaction and energy coupling could be stimulated or damaged by visible light. Our previous work demonstrated that reactive oxygen species (ROS) were generated in cultured astrocytes after visible laser irradiation. With confocal fluorescence microscopy, we found that ROS were generated mostly from mitochondria. This mitochondrial ROS (mROS) formation plays a critical role in photoirradiation-induced phototoxicity and apoptosis. In this study, we measured changes of mitochondrial calcium level ([Ca(2+)](m)) in cultured astrocytes (RBA-1 cell line) irradiated with blue light and examined the association between mROS formation and [Ca(2+)](m) level changes. Changes of intracellular ROS and [Ca(2+)](m) were visualized using fluorescent probes 2',7'-dichlorodihydrofluorescein (DCF), and rhod-2. After exposure to visible light irradiation, RBA-1 astrocytes showed a rapid increase in ROS accumulation particularly in the mitochondrial area. Increase in [Ca(2+)](m) was also induced by photoirradiation. The levels of increase in DCF fluorescence intensity varied among different astrocytes. Some of the cells generated much higher levels of ROS than others. For those cells that had high ROS levels, mitochondrial Ca(2+) levels were also high. In cells that had mild ROS levels, mitochondrial Ca(2+) levels were only slightly increased. The rate of increase in DCF fluorescence seemed to be close to the rate of rhod-2 fluorescence increase. There is a positive and close correlation between mitochondrial ROS levels and mitochondrial Ca(2+) levels in astrocytes irradiated by visible light.

  5. PKCα promotes generation of reactive oxygen species via DUOX2 in hepatocellular carcinoma

    SciTech Connect

    Wang, Jiajun; Shao, Miaomiao; Liu, Min; Peng, Peike; Li, Lili; Wu, Weicheng; Wang, Lan; Duan, Fangfang; Zhang, Mingming; Song, Shushu; Jia, Dongwei; Ruan, Yuanyuan; Gu, Jianxin

    2015-08-07

    Hepatocellular carcinoma (HCC) remains the second leading cause of cancer-related death worldwide, and elevated rates of reactive oxygen species (ROS) have long been considered as a hallmark of almost all types of cancer including HCC. Protein kinase C alpha (PKCα), a serine/threonine kinase among conventional PKC family, is recognized as a major player in signal transduction and tumor progression. Overexpression of PKCα is commonly observed in human HCC and associated with its poor prognosis. However, how PKCα is involved in hepatocellular carcinogenesis remains not fully understood. In this study, we found that among the members of conventional PKC family, PKCα, but not PKCβI or βII, promoted ROS production in HCC cells. PKCα stimulated generation of ROS by up-regulating DUOX2 at post-transcriptional level. Depletion of DUOX2 abrogated PKCα-induced activation of AKT/MAPK pathways as well as cell proliferation, migration and invasion in HCC cells. Moreover, the expression of DUOX2 and PKCα was well positively correlated in both HCC cell lines and patient samples. Collectively, our findings demonstrate that PKCα plays a critical role in HCC development by inducing DUOX2 expression and ROS generation, and propose a strategy to target PKCα/DUOX2 as a potential adjuvant therapy for HCC treatment. - Highlights: • PKCα promotes the generation of ROS in hepatocellular carcinoma. • PKCα induces ROS production by up-regulating DUOX2 at post-transcriptional level. • DUOX2 is required for PKCα-induced AKT/MAPK activation and tumor progression in HCC. • The expression of PKCα is positively correlated with DUOX2 in HCC.

  6. Nucleotide Receptor Signaling in Murine Macrophages Is Linked to Reactive Oxygen Species Generation1

    PubMed Central

    Pfeiffer, Zachary A.; Guerra, Alma N.; Hill, Lindsay M.; Gavala, Monica L.; Prabhu, Usha; Aga, Mini; Hall, David J.; Bertics, Paul J.

    2007-01-01

    Macrophage activation is critical in the innate immune response and can be regulated by the nucleotide receptor P2X7. In this regard, P2X7 signaling is not well understood but has been implicated in controlling reactive oxygen species (ROS) generation by various leukocytes. Although ROS can contribute to microbial killing, the role of ROS in nucleotide-mediated cell signaling is unclear. In this study, we report that the P2X7 agonists ATP and 3′-O-(4-benzoyl) benzoic ATP (BzATP) stimulate ROS production by RAW 264.7 murine macrophages. These effects are potentiated in lipopolysaccharide-primed cells, demonstrating an important interaction between extracellular nucleotides and microbial products in ROS generation. In terms of nucleotide receptor specificity, RAW 264.7 macrophages that are deficient in P2X7 are greatly reduced in their capacity to generate ROS in response to BzATP treatment (both with and without LPS priming), thus supporting a role for P2X7 in this process. Because MAP kinase activation is key for nucleotide regulation of macrophage function, we also tested the hypothesis that P2X7-mediated MAP kinase activation is dependent on ROS production. We observed that BzATP stimulates MAP kinase (ERK1/ERK2, p38, and JNK1/JNK2) phosphorylation, and that the antioxidants N-acetyl-cysteine and ascorbic acid strongly attenuate BzATP-mediated JNK1/JNK2 and p38 phosphorylation but only slightly reduce BzATP-induced ERK1/ERK2 phosphorylation. These studies reveal that P2X7 can contribute to macrophage ROS production, that this effect is potentiated upon lipopolysaccharide exposure, and that ROS are important participants in the extracellular nucleotide-mediated activation of several MAP kinase systems. PMID:17448897

  7. Composition Directed Generation of Reactive Oxygen Species in Irradiated Mixed Metal Sulfides Correlated with Their Photocatalytic Activities.

    PubMed

    He, Weiwei; Jia, Huimin; Yang, Dongfang; Xiao, Pin; Fan, Xiaoli; Zheng, Zhi; Kim, Hyun-Kyung; Wamer, Wayne G; Yin, Jun-Jie

    2015-08-05

    The ability of nanostructures to facilitate the generation of reactive oxygen species and charge carriers underlies many of their chemical and biological activities. Elucidating which factors are essential and how these influence the production of various active intermediates is fundamental to understanding potential applications of these nanostructures, as well as potential risks. Using electron spin resonance spectroscopy coupled with spin trapping and spin labeling techniques, we assessed 3 mixed metal sulfides of varying compositions for their abilities to generate reactive oxygen species, photogenerate electrons, and consume oxygen during photoirradiation. We found these irradiated mixed metal sulfides exhibited composition dependent generation of ROS: ZnIn2S4 can generate (•)OH, O2(-•) and (1)O2; CdIn2S4 can produce O2(-•) and (1)O2, while AgInS2 only produces O2(-•). Our characterizations of the reactivity of the photogenerated electrons and consumption of dissolved oxygen, performed using spin labeling, showed the same trend in activity: ZnIn2S4 > CdIn2S4 > AgInS2. These intrinsic abilities to generate ROS and the reactivity of charge carriers correlated closely with the photocatalytic degradation and photoassisted antibacterial activities of these nanomaterials.

  8. Evaluating the therapeutic potential of idebenone and related quinone analogues in Leber hereditary optic neuropathy.

    PubMed

    Yu-Wai-Man, Patrick; Soiferman, Devorah; Moore, David G; Burté, Florence; Saada, Ann

    2017-09-01

    Leber hereditary optic neuropathy (LHON) is an important cause of mitochondrial blindness among young adults. In this study, we investigated the potential of four quinone analogues (CoQ1, CoQ10, decylubiquinone and idebenone) in compensating for the deleterious effect of the m.11778G>A mitochondrial DNA mutation. The LHON fibroblast cell lines tested exhibited reduced cell growth, impaired mitochondrial bioenergetics and elevated levels of reactive oxygen species (ROS). Idebenone increased ATP production and reduced ROS levels, but the effect was partial and cell-specific. The remaining quinone analogues had variable effects and a negative impact on certain mitochondrial parameters was observed in some cell lines. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  9. Proteomic analysis of rat brain mitochondria following exposure to dopamine quinone: implications for Parkinson disease.

    PubMed

    Van Laar, Victor S; Dukes, April A; Cascio, Michael; Hastings, Teresa G

    2008-03-01

    Oxidative stress and mitochondrial dysfunction have been linked to dopaminergic neuron degeneration in Parkinson disease. We have previously shown that dopamine oxidation leads to selective dopaminergic terminal degeneration in vivo and alters mitochondrial function in vitro. In this study, we utilized 2-D difference in-gel electrophoresis to assess changes in the mitochondrial proteome following in vitro exposure to reactive dopamine quinone. A subset of proteins exhibit decreased fluorescence labeling following dopamine oxidation, suggesting a rapid loss of specific proteins. Amongst these proteins are mitochondrial creatine kinase, mitofilin, mortalin, the 75 kDa subunit of NADH dehydrogenase, and superoxide dismutase 2. Western blot analyses for mitochondrial creatine kinase and mitofilin confirmed significant losses in isolated brain mitochondria exposed to dopamine quinone and PC12 cells exposed to dopamine. These results suggest that specific mitochondrial proteins are uniquely susceptible to changes in abundance following dopamine oxidation, and carry implications for mitochondrial stability in Parkinson disease neurodegeneration.

  10. Induction of quinone reductase (QR) by withanolides isolated from Physalis angulata L. var. villosa Bonati (Solanaceae).

    PubMed

    Ding, Hui; Hu, Zhijuan; Yu, Liyan; Ma, Zhongjun; Ma, Xiaoqiong; Chen, Zhe; Wang, Dan; Zhao, Xiaofeng

    2014-08-01

    In the present study, the EtOAc extract of the persistent calyx of Physalis angulata L. var. villosa Bonati (PA) was tested for its potential quinone reductase (QR) inducing activity with glutathione (GSH) as the substrate using an UPLC-ESI-MS method. The result revealed that the PA had electrophiles that could induce quinone reductase (QR) activity, which might be attributed to the modification of the highly reactive cysteine residues in Keap1. Herein, three new withanolides, compounds 3, 6 and 7, together with four known withanolides, compounds 1, 2, 4 and 5 were isolated from PA extract. Their structures were determined by spectroscopic techniques, including (1)H-, (13)C NMR (DEPT), and 2D-NMR (HMBC, HMQC, (1)H, (1)H-COSY, NOESY) experiments, as well as by HR-MS. All the seven compounds were tested for their QR induction activities towards mouse hepa 1c1c7 cells.

  11. Quinone emissions from gasoline and diesel motor vehicles.

    PubMed

    Jakober, Chris A; Riddle, Sarah G; Robert, Michael A; Destaillats, Hugo; Charles, M Judith; Green, Peter G; Kleeman, Michael J

    2007-07-01

    Gas- and particle-phase emissions from gasoline and diesel vehicles operated on chassis dynamometers were collected using annular denuders, quartz filters, and PUF substrates. Quinone species were measured using O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine derivatization in conjunction with gas chromatography-mass spectrometry and high-performance liquid chromatography-mass spectrometry. Nine quinones were observed, ranging from C6 to C16. New species identified in motor vehicle exhaust include methyl-1,4-benzoquinone, 2-methyl-1,4-naphthoquinone (MNQN), and aceanthrenequinone. Gas-phase motor vehicle emissions of quinones are also reported for the first time. Six gas-phase quinones were quantified with emission rates of 2-28 000 microg L(-1) fuel consumed. The most abundant gas-phase quinones were 1,4-benzoquinone (BON) and MNQN. The gas-phase fraction was > or = 69% of quinone mass for light-duty gasoline emissions, and > or = 84% for heavy-duty diesel emissions. Eight particle-phase quinones were observed between 2 and 1600 microg L(-1), with BQN the most abundant species followed by 9,10-phenanthrenequinone and 1,2-naphthoquinone. Current particle-phase quinone measurements agree well with the few available previous results. Further research is needed concerning the gas-particle partitioning behavior of quinones in ambient and combustion source conditions.

  12. Efficient generation of cavitation bubbles and reactive oxygen species using triggered high-intensity focused ultrasound sequence for sonodynamic treatment

    NASA Astrophysics Data System (ADS)

    Yasuda, Jun; Yoshizawa, Shin; Umemura, Shin-ichiro

    2016-07-01

    Sonodynamic treatment is a method of treating cancer using reactive oxygen species (ROS) generated by cavitation bubbles in collaboration with a sonosensitizer at a target tissue. In this treatment method, both localized ROS generation and ROS generation with high efficiency are important. In this study, a triggered high-intensity focused ultrasound (HIFU) sequence, which consists of a short, extremely high intensity pulse immediately followed by a long, moderate-intensity burst, was employed for the efficient generation of ROS. In experiments, a solution sealed in a chamber was exposed to a triggered HIFU sequence. Then, the distribution of generated ROS was observed by the luminol reaction, and the amount of generated ROS was quantified using KI method. As a result, the localized ROS generation was demonstrated by light emission from the luminol reaction. Moreover, it was demonstrated that the triggered HIFU sequence has higher efficiency of ROS generation by both the KI method and the luminol reaction emission.

  13. Hysteresis Behaviors of Poly (Naphthalene Quinone) Radical Electrorheological Fluid

    NASA Astrophysics Data System (ADS)

    Choi, Hyoung J.; Cho, Min S.; Jhon, Myung S.

    As a potential electrorheological(ER) material, poly(naphthalene quinone) radical (PNQR) ER fluid was prepared, and its rheological behavior and hysteresis phenomenon were investigated. PNQR was synthesized by Friedel-Crafts acylation between naphthalene and phthalic anhydride, using zinc chloride as a catalyst at 256°C. A Physica rheometer equipped with a high voltage generator was used to measure the rheological properties of the ER fluids, which were prepared by dispersing PNQR in silicone oil at several particle concentrations. Shear stresses were observed to decrease as shear rate increased in the region of slow deformation rate. It was further found that ER fluid showed different hysteresis behaviors according to the shear rate ranges; thixotropy was observed in the low shear rate region (0.007-0.51/s) and anti-thixotropy in the high shear rate region (0.5-10001/s). Controlled shear stress mode was also applied to observe similar behaviors.

  14. Controlled intracellular generation of reactive oxygen species in human mesenchymal stem cells using porphyrin conjugated nanoparticles

    NASA Astrophysics Data System (ADS)

    Lavado, Andrea S.; Chauhan, Veeren M.; Alhaj Zen, Amer; Giuntini, Francesca; Jones, D. Rhodri E.; Boyle, Ross W.; Beeby, Andrew; Chan, Weng C.; Aylott, Jonathan W.

    2015-08-01

    Nanoparticles capable of generating controlled amounts of intracellular reactive oxygen species (ROS), that advance the study of oxidative stress and cellular communication, were synthesized by functionalizing polyacrylamide nanoparticles with zinc(ii) porphyrin photosensitisers. Controlled ROS production was demonstrated in human mesenchymal stem cells (hMSCs) through (1) production of nanoparticles functionalized with varying percentages of Zn(ii) porphyrin and (2) modulating the number of doses of excitation light to internalized nanoparticles. hMSCs challenged with nanoparticles functionalized with increasing percentages of Zn(ii) porphyrin and high numbers of irradiations of excitation light were found to generate greater amounts of ROS. A novel dye, which is transformed into fluorescent 7-hydroxy-4-trifluoromethyl-coumarin in the presence of hydrogen peroxide, provided an indirect indicator for cumulative ROS production. The mitochondrial membrane potential was monitored to investigate the destructive effect of increased intracellular ROS production. Flow cytometric analysis of nanoparticle treated hMSCs suggested irradiation with excitation light signalled controlled apoptotic cell death, rather than uncontrolled necrotic cell death. Increased intracellular ROS production did not induce phenotypic changes in hMSC subcultures.Nanoparticles capable of generating controlled amounts of intracellular reactive oxygen species (ROS), that advance the study of oxidative stress and cellular communication, were synthesized by functionalizing polyacrylamide nanoparticles with zinc(ii) porphyrin photosensitisers. Controlled ROS production was demonstrated in human mesenchymal stem cells (hMSCs) through (1) production of nanoparticles functionalized with varying percentages of Zn(ii) porphyrin and (2) modulating the number of doses of excitation light to internalized nanoparticles. hMSCs challenged with nanoparticles functionalized with increasing percentages of Zn

  15. Incorporating Geochemical And Microbial Kinetics In Reactive Transport Models For Generation Of Acid Rock Drainage

    NASA Astrophysics Data System (ADS)

    Andre, B. J.; Rajaram, H.; Silverstein, J.

    2010-12-01

    diffusion model at the scale of a single rock is developed incorporating the proposed kinetic rate expressions. Simulations of initiation, washout and AMD flows are discussed to gain a better understanding of the role of porosity, effective diffusivity and reactive surface area in generating AMD. Simulations indicate that flow boundary conditions control generation of acid rock drainage as porosity increases.

  16. 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.

  17. Copper chelation selectively kills colon cancer cells through redox cycling and generation of reactive oxygen species.

    PubMed

    Fatfat, Maamoun; Merhi, Raghida Abou; Rahal, Omar; Stoyanovsky, Detcho A; Zaki, Angela; Haidar, Hazar; Kagan, Valerian E; Gali-Muhtasib, Hala; Machaca, Khaled

    2014-07-21

    Metals including iron, copper and zinc are essential for physiological processes yet can be toxic at high concentrations. However the role of these metals in the progression of cancer is not well defined. Here we study the anti-tumor activity of the metal chelator, TPEN, and define its mechanism of action. Multiple approaches were employed, including cell viability, cell cycle analysis, multiple measurements of apoptosis, and mitochondrial function. In addition we measured cellular metal contents and employed EPR to record redox cycling of TPEN-metal complexes. Mouse xenografts were also performed to test the efficacy of TPEN in vivo. We show that metal chelation using TPEN (5μM) selectively induces cell death in HCT116 colon cancer cells without affecting the viability of non-cancerous colon or intestinal cells. Cell death was associated with increased levels of reactive oxygen species (ROS) and was inhibited by antioxidants and by prior chelation of copper. Interestingly, HCT116 cells accumulate copper to 7-folds higher levels than normal colon cells, and the TPEN-copper complex engages in redox cycling to generate hydroxyl radicals. Consistently, TPEN exhibits robust anti-tumor activity in vivo in colon cancer mouse xenografts. Our data show that TPEN induces cell death by chelating copper to produce TPEN-copper complexes that engage in redox cycling to selectively eliminate colon cancer cells.

  18. Bistability of mitochondrial respiration underlies paradoxical reactive oxygen species generation induced by anoxia.

    PubMed

    Selivanov, Vitaly A; Votyakova, Tatyana V; Zeak, Jennifer A; Trucco, Massimo; Roca, Josep; Cascante, Marta

    2009-12-01

    Increased production of reactive oxygen species (ROS) in mitochondria underlies major systemic diseases, and this clinical problem stimulates a great scientific interest in the mechanism of ROS generation. However, the mechanism of hypoxia-induced change in ROS production is not fully understood. To mathematically analyze this mechanism in details, taking into consideration all the possible redox states formed in the process of electron transport, even for respiratory complex III, a system of hundreds of differential equations must be constructed. Aimed to facilitate such tasks, we developed a new methodology of modeling, which resides in the automated construction of large sets of differential equations. The detailed modeling of electron transport in mitochondria allowed for the identification of two steady state modes of operation (bistability) of respiratory complex III at the same microenvironmental conditions. Various perturbations could induce the transition of respiratory chain from one steady state to another. While normally complex III is in a low ROS producing mode, temporal anoxia could switch it to a high ROS producing state, which persists after the return to normal oxygen supply. This prediction, which we qualitatively validated experimentally, explains the mechanism of anoxia-induced cell damage. Recognition of bistability of complex III operation may enable novel therapeutic strategies for oxidative stress and our method of modeling could be widely used in systems biology studies.

  19. Silver nanoparticle-algae interactions: oxidative dissolution, reactive oxygen species generation and synergistic toxic effects.

    PubMed

    He, Di; Dorantes-Aranda, Juan José; Waite, T David

    2012-08-21

    The short-term toxicity of citrate-stabilized silver nanoparticles (AgNPs) and ionic silver Ag(I) to the ichthyotoxic marine raphidophyte Chattonella marina has been examined using the fluorometric indicator alamarBlue. Aggregation and dissolution of AgNPs occurred after addition to GSe medium while uptake of dissolved Ag(I) occurred in the presence of C. marina. Based on total silver mass, toxicity was much higher for Ag(I) than for AgNPs. Cysteine, a strong Ag(I) ligand, completely removed the inhibitory effects of Ag(I) and AgNPs on the metabolic activity of C. marina, suggesting that the toxicity of AgNPs was due to the release of Ag(I). Synergistic toxic effects of AgNPs/Ag(I) and C. marina to fish gill cells were observed with these effects possibly attributable to enhancement in the generation of reactive oxygen species by C. marina on exposure of the organism to silver.

  20. Native low density lipoprotein induces pancreatic β cell apoptosis through generating excess reactive oxygen species.

    PubMed

    Lu, Xiuli; Liu, Jianli; Cao, Xiangyu; Hou, Xiao; Wang, Xude; Zhao, Chenguang; Wang, Youliang; Li, Yang; Seo, Hisao; Gao, Bing

    2011-07-26

    The growing evidences demonstrated hyperlipidemia in obesity and type 2 diabetes is characterized by high levels of free fatty acids, low-density lipoprotein (LDL), triglyceride, and cholesterol. We investigated the effect of LDL particles (LDLs) loading on MIN6 cells derived from pancreatic β cells. Exposure of MIN6 cells to LDLs induced apoptosis in dose and time-dependent manner, demonstrated by the TUNEL in situ apoptotic assay. The immunocytochemical analysis and Western blotting revealed that the LDLs-induced apoptosis is associated with the activation of caspase 3 and upregulation of p53. The intracellular concentration of Reactive Oxygen Species (ROS) measured by use of DCFHDA was significantly increased after loading LDLs, demonstrating the induced apoptosis by LDLs loading was mediated through oxidative stress. Addition of reduced form of Glutathione (GSH) in the medium rescued MIN6 cells from apoptosis. The Cellular cholesterol level was increased significantly after LDLs loading, suggesting that the excess cholesterol induced by LDLs loading might contribute to the apoptosis in MIN6s. Agarose electrophoresis demonstrated that the LDLs added to the medium were not oxidized. Taken together, these results demonstrate that the LDLs loading can induce apoptosis of MIN6 cells mediated by the excess cellular cholesterol and generation of oxidative stress.

  1. Heavy metals generate reactive oxygen species in terrestrial and aquatic ciliated protozoa.

    PubMed

    Rico, Daniel; Martín-González, Ana; Díaz, Silvia; de Lucas, Pilar; Gutiérrez, Juan-Carlos

    2009-01-01

    Reactive oxygen species (ROS) induction by exposure to heavy metals (Cd, Cu or Zn) in diverse free-living ciliated protozoa (Tetrahymena sp. and three strains of Colpoda steinii, isolated from freshwater and soils with different level of metal pollution) has been evaluated. Using specific fluorophores, such as 2',7'-dichlorofluorescein diacetate, hydroethidine and dihydrorhodamine 123, and a fluorescence microscope with the program MetaMorph Imaging System 4.0, we have analyzed both the average fluorescence emission and the heterogeneous distribution of fluorescence in control and treated cells. This is the first time that these fluorophores are used to detect ROS production in ciliated protozoa. All metals generate ROS, mainly superoxide and peroxides, showing a remarkable inter- and intra-specific variations. Likewise, resistance against each metal was also very diverse. Cu and specially Cd, the most toxic heavy metal for these ciliates, are the best oxidative stress inducers. However, a correlation between fluorescence emission intensity and cellular metal sensitivity for each strain cannot be established. Results are discussed and compared with similar findings previously published in other unicellular and pluricellular organisms.

  2. Biodegradable fibres spun from poly(lactide) generated by reactive extrusion.

    PubMed

    Schmack, G; Jehnichen, D; Vogel, R; Tändler, B; Beyreuther, R; Jacobsen, S; Fritz, H G

    2001-03-30

    Poly(lactide) (PLA) was spun both in a high speed spinning process with take-up velocities of 1000-5000 m min(-1) and in a spin drawing process at draw ratios of 4-6. The effect of the melt spinning conditions on the development of the structural hierarchy in the fibres and the relations to the textile physical properties were investigated. The PLA fibres were characterised with regard to the degree of crystallinity by DSC and WAXS, the orientation by WAXS and birefringence, and the stress-strain behaviour. The maximum physical break stress and the E-modulus observed in the spin drawn fibres were about 490 MPa and 6.3 GPa, respectively, at an elongation at break of 30%. The PLA was a copolymer of L-lactide (92 wt.%) and meso-lactide (8 wt.%) and was generated by reactive extrusion polymerisation. The PLA virgin pellets were analysed regarding their degradation during the spinning processes. Their thermal and rheological properties were determined by DSC and dynamic rheological measurements, respectively, to derive suitable parameters for the melt spinning processes.

  3. Cryptococcus neoformans capsule protects cell from oxygen reactive species generated by antimicrobial photodynamic inactivation

    NASA Astrophysics Data System (ADS)

    Prates, Renato Araujo; Hamblin, Michael R.; Kato, Ilka T.; Fuchs, Beth; Mylonakis, Eleytherios; Simões Ribeiro, Martha; Tegos, George

    2011-03-01

    Antimicrobial photodynamic inactivation (APDI) is based on the utilization of substances that can photosensitize biological tissues and are capable of being activated in the presence of light. Cryptococcus neoformans is an yeast surrounded by a capsule composed primarily of glucoronoxylomannan that plays an important role in its virulence. This yeast causes infection on skin, lungs and brain that can be associated with neurological sequelae and neurosurgical interventions, and its conventional treatment requires prolonged antifungal therapy, which presents important adverse effects. The aim of this study was to evaluate the protective effect of Cryptococcus neoformans capsule against reactive oxygen species generated by APDI. Cryptococcus neoformans KN99α, which is a strain able to produce capsule, and CAP59 that does not present capsule production were submitted to APDI using methylene blue (MB), rose bengal (RB), and pL-ce6 as photosensitizers (PS). Then microbial inactivation was evaluated by counting colony form units following APDI and confocal laser scanning microscopy (CLSM) illustrated localization as well as the preferential accumulation of PS into the fungal cells. C. neoformans KN99α was more resistant to APDI than CAP59 for all PSs tested. CLSM showed incorporation of MB and RB into the cytoplasm and a preferential uptake in mitochondria. A nuclear accumulation of MB was also observed. Contrarily, pL-ce6 appears accumulated in cell wall and cell membrane and minimal florescence was observed inside the fungal cells. In conclusion, the ability of C. neoformans to form capsule enhances survival following APDI.

  4. Effect of reactive oxygen species (ROS) generating system for control of airborne microorganisms in meat processing environment

    USDA-ARS?s Scientific Manuscript database

    The effectiveness of reactive oxygen species (ROS) generating AirOcare equipment on the reduction of airborne bacteria in a meat processing environment was determined. Serratia marcescens and lactic acid bacteria (Lactococcus lactis subsp. lactis and Lactobacillus plantarum) were used to artificiall...

  5. New heterocyclic precursors for thermal generation of reactive, electron-rich 1,2-diaza-1,3-butadienes.

    PubMed

    Boeckman, R K; Ge, P; Reed, J E

    2001-11-15

    [reaction--see text] [corrected] The preparation and thermolysis of new stable heterocyclic precursors of 1,2-diaza-1,3-butadienes is described. The resulting reactive diazadienes are trapped in situ with N-phenylmaleimide [corrected]. The effect of precursor structure on the temperature at which the diazadienes are generated is discussed.

  6. A Porous Tissue Engineering Scaffold Selectively Degraded by Cell-Generated Reactive Oxygen Species

    PubMed Central

    Martin, John R.; Gupta, Mukesh K.; Page, Jonathan M.; Yu, Fang; Davidson, Jeffrey M.; Guelcher, Scott A.

    2014-01-01

    Biodegradable tissue engineering scaffolds are commonly fabricated from poly(lactide-co-glycolide) (PLGA) or similar polyesters that degrade by hydrolysis. PLGA hydrolysis generates acidic breakdown products that trigger an accelerated, autocatalytic degradation mechanism that can create mismatched rates of biomaterial breakdown and tissue formation. Reactive oxygen species (ROS) are key mediators of cell function in both health and disease, especially at sites of inflammation and tissue healing, and induction of inflammation and ROS are natural components of the in vivo response to biomaterial implantation. Thus, polymeric biomaterials that are selectively degraded by cell-generated ROS may have potential for creating tissue engineering scaffolds with better matched rates of tissue in-growth and cell-mediated scaffold biodegradation. To explore this approach, a series of poly(thioketal) (PTK) urethane (PTK-UR) biomaterial scaffolds were synthesized that degrade specifically by an ROS-dependent mechanism. PTK-UR scaffolds had significantly higher compressive moduli than analogous poly(ester urethane) (PEUR) scaffolds formed from hydrolytically-degradable ester-based diols (p < 0.05). Unlike PEUR scaffolds, the PTK-UR scaffolds were stable under aqueous conditions out to 25 weeks but were selectively degraded by ROS, indicating that their biodegradation would be exclusively cell-mediated. The in vitro oxidative degradation rates of the PTK-URs followed first-order degradation kinetics, were significantly dependent on PTK composition (p < 0.05), and correlated to ROS concentration. In subcutaneous rat wounds, PTK-UR scaffolds supported cellular infiltration and granulation tissue formation, followed first-order degradation kinetics over 7 weeks, and produced significantly greater stenting of subcutaneous wounds compared to PEUR scaffolds. These combined results indicate that ROS-degradable PTK-UR tissue engineering scaffolds have significant advantages over analogous

  7. Pathophysiological and pharmacological implications of mitochondria-targeted reactive oxygen species generation in astrocytes.

    PubMed

    Jou, Mei-Jie

    2008-01-01

    Astrocytes, in addition to passively supporting neurons, have recently been shown to be actively involved in synaptic transmission and neurovascular coupling in the central nervous system (CNS). This review summarizes briefly our previous observations using fluorescent probes coupled with laser scanning digital imaging microscopy to visualize spatio-temporal alteration of mitochondrial reactive oxygen species (mROS) generation in intact astrocytes. mROS formation is enhanced by exogenous oxidants exposure, Ca2+ stress and endogenous pathological defect of mitochondrial respiratory complexes. In addition, mROS formation can be specifically stimulated by visible light or visible laser irradiation and can be augmented further by photodynamic coupling with photosensitizers, particularly with mitochondria-targeted photosensitizers. "Severe" oxidative insult often results in massive and homogeneous augmentation of mROS formation which causes cessation of mitochondrial movement, pathological fission and irreversible swelling of mitochondria and eventually apoptosis or necrosis of cells. Mitochondria-targeted antioxidants and protectors such as MitoQ, melatonin and nanoparticle C(60) effectively prevent "severe" mROS generation. Intriguingly, "minor" oxidative insults enhance heterogeneity of mROS and mitochondrial dynamics. "Minor" mROS formation-induced fission and fusion of mitochondria relocates mitochondrial network to form a mitochondria free gap, i.e., "firewall", which may play a crucial role in mROS-mediated protective "preconditioning" by preventing propagation of mROS during oxidative insults. These mROS-targeted strategies for either enhancement or prevention of mitochondrial oxidative stress in astrocytes may provide new insights for future development of therapeutic interventions in the treatment of cancer such as astrocytomas and gliomas and astrocyte-associated neurodegeneration, mitochondrial diseases and aging.

  8. Biochemistry: is pyrroloquinoline quinone a vitamin?

    PubMed

    Rucker, Robert; Storms, David; Sheets, Annemarie; Tchaparian, Eskouhie; Fascetti, Andrea

    2005-02-03

    The announcement by Kasahara and Kato of pyrroloquinoline quinone (PQQ) as a 'new' vitamin has received considerable attention. We have since attempted to reproduce the findings on which their conclusion is based, namely that defects in lysine metabolism occur in PQQ-deprived rodents. However, we find that the activity of alpha-aminoadipic acid-delta-semialdehyde (AAS) dehydrogenase in liver and plasma levels of alpha-aminoadipic acid (AAA), both of which act as indicators of lysine degradation in mammals, are not affected by changes in PQQ dietary status. Our results call into question the identification of PQQ as a new vitamin.

  9. The pattern of p53 mutations caused by PAH o-quinones is driven by 8-oxo-dGuo formation while the spectrum of mutations is determined by biological selection for dominance.

    PubMed

    Park, Jong-Heum; Gelhaus, Stacy; Vedantam, Srilakshmi; Oliva, Andrea L; Batra, Abhita; Blair, Ian A; Troxel, Andrea B; Field, Jeffrey; Penning, Trevor M

    2008-05-01

    PAHs (polycyclic aromatic hydrocarbons) are suspect lung cancer carcinogens that must be metabolically converted into DNA-reactive metabolites. P4501A1/P4501B1 plus epoxide hydrolase activate PAH to (+/-)- anti-benzo[ a]pyrene diol epoxide ((+/-)- anti-BPDE), which causes bulky DNA adducts. Alternatively, aldo-keto reductases (AKRs) convert intermediate PAH trans-dihydrodiols to o-quinones, which cause DNA damage by generating reactive oxygen species (ROS). In lung cancer, the types or pattern of mutations in p53 are predominantly G to T transversions. The locations of these mutations form a distinct spectrum characterized by single point mutations in a number of hotspots located in the DNA binding domain. One route to the G to T transversions is via oxidative DNA damage. An RP-HPLC-ECD assay was used to detect the formation of 8-oxo-dGuo in p53 cDNA exposed to representative quinones, BP-7,8-dione, BA-3,4-dione, and DMBA-3,4-dione under redox cycling conditions. Concurrently, a yeast reporter system was used to detect mutations in the same cDNA samples. Nanomolar concentrations of PAH o-quinones generated 8-oxo-dGuo (detected by HPLC-ECD) in a concentration dependent manner that correlated in a linear fashion with mutagenic frequency. By contrast, micromolar concentrations of (+/-)- anti-BPDE generated (+)- trans- anti-BPDE-N (2)-dGuo adducts (detected by stable-isotope dilution LC/MS methodology) in p53 cDNA that correlated in a linear fashion with mutagenic frequency, but no 8-oxo-dGuo was detected. Previous studies found that mutations observed with PAH o-quinones were predominately G to T transversions and those observed with (+/-)- anti-BPDE were predominately G to C transversions. However, mutations at guanine bases observed with either PAH-treatment occurred randomly throughout the DNA-binding domain of p53. Here, we find that when the mutants were screened for dominance, the dominant mutations clustered at or near hotspots primarily at the protein

  10. Cancer Therapy by Catechins Involves Redox Cycling of Copper Ions and Generation of Reactive Oxygen species.

    PubMed

    Farhan, Mohd; Khan, Husain Yar; Oves, Mohammad; Al-Harrasi, Ahmed; Rehmani, Nida; Arif, Hussain; Hadi, Sheikh Mumtaz; Ahmad, Aamir

    2016-02-04

    Catechins, the dietary phytochemicals present in green tea and other beverages, are considered to be potent inducers of apoptosis and cytotoxicity to cancer cells. While it is believed that the antioxidant properties of catechins and related dietary agents may contribute to lowering the risk of cancer induction by impeding oxidative injury to DNA, these properties cannot account for apoptosis induction and chemotherapeutic observations. Catechin (C), epicatechin (EC), epigallocatechin (EGC) and epigallocatechin-3-gallate (EGCG) are the four major constituents of green tea. In this article, using human peripheral lymphocytes and comet assay, we show that C, EC, EGC and EGCG cause cellular DNA breakage and can alternatively switch to a prooxidant action in the presence of transition metals such as copper. The cellular DNA breakage was found to be significantly enhanced in the presence of copper ions. Catechins were found to be effective in providing protection against oxidative stress induced by tertbutylhydroperoxide, as measured by oxidative DNA breakage in lymphocytes. The prooxidant action of catechins involved production of hydroxyl radicals through redox recycling of copper ions. We also determined that catechins, particularly EGCG, inhibit proliferation of breast cancer cell line MDA-MB-231 leading to a prooxidant cell death. Since it is well established that tissue, cellular and serum copper levels are considerably elevated in various malignancies, cancer cells would be more subject to redox cycling between copper ions and catechins to generate reactive oxygen species (ROS) responsible for DNA breakage. Such a copper dependent prooxidant cytotoxic mechanism better explains the anticancer activity and preferential cytotoxicity of dietary phytochemicals against cancer cells.

  11. Cancer Therapy by Catechins Involves Redox Cycling of Copper Ions and Generation of Reactive Oxygen Species

    PubMed Central

    Farhan, Mohd; Khan, Husain Yar; Oves, Mohammad; Al-Harrasi, Ahmed; Rehmani, Nida; Arif, Hussain; Hadi, Sheikh Mumtaz; Ahmad, Aamir

    2016-01-01

    Catechins, the dietary phytochemicals present in green tea and other beverages, are considered to be potent inducers of apoptosis and cytotoxicity to cancer cells. While it is believed that the antioxidant properties of catechins and related dietary agents may contribute to lowering the risk of cancer induction by impeding oxidative injury to DNA, these properties cannot account for apoptosis induction and chemotherapeutic observations. Catechin (C), epicatechin (EC), epigallocatechin (EGC) and epigallocatechin-3-gallate (EGCG) are the four major constituents of green tea. In this article, using human peripheral lymphocytes and comet assay, we show that C, EC, EGC and EGCG cause cellular DNA breakage and can alternatively switch to a prooxidant action in the presence of transition metals such as copper. The cellular DNA breakage was found to be significantly enhanced in the presence of copper ions. Catechins were found to be effective in providing protection against oxidative stress induced by tertbutylhydroperoxide, as measured by oxidative DNA breakage in lymphocytes. The prooxidant action of catechins involved production of hydroxyl radicals through redox recycling of copper ions. We also determined that catechins, particularly EGCG, inhibit proliferation of breast cancer cell line MDA-MB-231 leading to a prooxidant cell death. Since it is well established that tissue, cellular and serum copper levels are considerably elevated in various malignancies, cancer cells would be more subject to redox cycling between copper ions and catechins to generate reactive oxygen species (ROS) responsible for DNA breakage. Such a copper dependent prooxidant cytotoxic mechanism better explains the anticancer activity and preferential cytotoxicity of dietary phytochemicals against cancer cells. PMID:26861392

  12. Manipulation of environmental oxygen modifies reactive oxygen and nitrogen species generation during myogenesis.

    PubMed

    McCormick, Rachel; Pearson, Timothy; Vasilaki, Aphrodite

    2016-08-01

    Regulated changes in reactive oxygen and nitrogen species (RONS) activities are important in maintaining the normal sequence and development of myogenesis. Both excessive formation and reduction in RONS have been shown to affect muscle differentiation in a negative way. Cultured cells are typically grown in 20% O2 but this is not an appropriate physiological concentration for a number of cell types, including skeletal muscle. The aim was to examine the generation of RONS in cultured skeletal muscle cells under a physiological oxygen concentration condition (6% O2) and determine the effect on muscle myogenesis. Primary mouse satellite cells were grown in 20% or 6% O2 environments and RONS activity was measured at different stages of myogenesis by real-time fluorescent microscopy using fluorescent probes with different specificities i.e. dihydroethidium (DHE), 4-amino-5-methylamino-2',7'-difluorofluorescein diacetate (DAF-FM DA) and 5-(and-6)-chloromethyl-2',7' -dichlorodihydrofluorescein diacetate (CM-DCFH-DA). Data demonstrate that satellite cell proliferation increased when cells were grown in 6% O2 compared with 20% O2. Myoblasts grown in 20% O2 showed an increase in DCF fluorescence and DHE oxidation compared with myoblasts grown at 6% O2. Myotubes grown in 20% O2 also showed an increase in DCF and DAF-FM fluorescence and DHE oxidation compared with myotubes grown in 6% O2. The catalase and MnSOD contents were also increased in myoblasts and myotubes that were maintained in 20% O2 compared with myoblasts and myotubes grown in 6% O2. These data indicate that intracellular RONS activities in myoblasts and myotubes at rest are influenced by changes in environmental oxygen concentration and that the increased ROS may influence myogenesis in a negative manner. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  13. Biocompatible ZnS:Mn quantum dots for reactive oxygen generation and detection in aqueous media

    NASA Astrophysics Data System (ADS)

    Diaz-Diestra, Daysi; Beltran-Huarac, Juan; Bracho-Rincon, Dina P.; González-Feliciano, José A.; González, Carlos I.; Weiner, Brad R.; Morell, Gerardo

    2015-12-01

    We report here the versatility of Mn-doped ZnS quantum dots (ZnS:Mn QDs) synthesized in aqueous medium for generating reactive oxygen species and for detecting cells. Our experiments provide evidence leading to the elimination of Cd-based cores in CdSe/ZnS systems by substitution of Mn-doped ZnS. Advanced electron microscopy, X-ray diffraction, and optical spectroscopy were applied to elucidate the formation, morphology, and dispersion of the products. We study for the first time the ability of ZnS:Mn QDs to act as immobilizing agents for Tyrosinase (Tyr) enzyme. It was found that ZnS:Mn QDs show no deactivation of Tyr enzyme, which efficiently catalyzed the hydrogen peroxide (H2O2) oxidation and its eventual reduction (-0.063 V vs. Ag/AgCl) on the biosensor surface. The biosensor showed a linear response in the range of 12 μmol/L-0.1 mmol/L at low operation potential. Our observations are explained in terms of a catalase-cycled kinetic mechanism based on the binding of H2O2 to the axial position of one of the active copper sites of the oxy-Tyr during the catalase cycle to produce deoxy-Tyr. A singlet oxygen quantum yield of 0.62 in buffer and 0.54 in water was found when ZnS:Mn QDs were employed as a photosensitizer in the presence of a chemical scavenger and a standard dye. These results are consistent with a chemical trapping energy transfer mechanism. Our results also indicate that ZnS:Mn QDs are well tolerated by HeLa Cells reaching cell viabilities as high as 88 % at 300 µg/mL of QDs for 24 h of incubation. The ability of ZnS:Mn QDs as luminescent nanoprobes for bioimaging is also discussed.

  14. Elevated Generation of Reactive Oxygen/Nitrogen Species in Hantavirus Cardiopulmonary Syndrome

    PubMed Central

    Davis, Ian C.; Zajac, Allan J.; Nolte, Kurt B.; Botten, Jason; Hjelle, Brian; Matalon, Sadis

    2002-01-01

    Hantavirus cardiopulmonary syndrome (HCPS) is a life-threatening respiratory disease characterized by profound pulmonary edema and myocardial depression. Most cases of HCPS in North America are caused by Sin Nombre virus (SNV), which is carried asymptomatically by deer mice (Peromyscus maniculatus). The underlying pathophysiology of HCPS is poorly understood. We hypothesized that pathogenic SNV infection results in increased generation of reactive oxygen/nitrogen species (RONS), which contribute to the morbidity and mortality of HCPS. Human disease following infection with SNV or Andes virus was associated with increased nitrotyrosine (NT) adduct formation in the lungs, heart, and plasma and increased expression of inducible nitric oxide synthase (iNOS) in the lungs compared to the results obtained for normal human volunteers. In contrast, NT formation was not increased in the lungs or cardiac tissue from SNV-infected deer mice, even at the time of peak viral antigen expression. In a murine (Mus musculus) model of HCPS (infection of NZB/BLNJ mice with lymphocytic choriomeningitis virus clone 13), HCPS-like disease was associated with elevated expression of iNOS in the lungs and NT formation in plasma, cardiac tissue, and the lungs. In this model, intraperitoneal injection of 1400W, a specific iNOS inhibitor, every 12 h during infection significantly improved survival without affecting intrapulmonary fluid accumulation or viral replication, suggesting that cardiac damage may instead be the cause of mortality. These data indicate that elevated production of RONS is a feature of pathogenic New World hantavirus infection and that pharmacologic blockade of iNOS activity may be of therapeutic benefit in HCPS cases, possibly by ameliorating the myocardial suppressant effects of RONS. PMID:12134039

  15. Differential Stress-Induced Regulation of Two Quinone Reductases in the Brown Rot Basidiomycete Gloeophyllum trabeum

    PubMed Central

    Cohen, Roni; Suzuki, Melissa R.; Hammel, Kenneth E.

    2004-01-01

    Quinone reductases (QRDs) have two important functions in the basidiomycete Gloeophyllum trabeum, which causes brown rot of wood. First, a QRD is required to generate biodegradative hydroxyl radicals via redox cycling between two G. trabeum extracellular metabolites, 2,5-dimethoxyhydroquinone (2,5-DMHQ) and 2,5-dimethoxy-1,4-benzoquinone (2,5-DMBQ). Second, because 2,5-DMBQ is cytotoxic and 2,5-DMHQ is not, a QRD is needed to maintain the intracellular pool of these metabolites in the reduced form. Given their importance in G. trabeum metabolism, QRDs could prove useful targets for new wood preservatives. We have identified two G. trabeum genes, each existing in two closely related, perhaps allelic variants, that encode QRDs in the flavodoxin family. Past work with QRD1 and heterologous expression of QRD2 in this study confirmed that both genes encode NADH-dependent, flavin-containing QRDs. Real-time reverse transcription PCR analyses of liquid- and wood-grown cultures showed that qrd1 expression was maximal during secondary metabolism, coincided with the production of 2,5-DMBQ, and was moderately up-regulated by chemical stressors such as quinones. By contrast, qrd2 expression was maximal during fungal growth when 2,5-DMBQ levels were low, yet was markedly up-regulated by chemical stress or heat shock. The total QRD activity in lysates of G. trabeum mycelium was significantly enhanced by induction beforehand with a cytotoxic quinone. The promoter of qrd2 contains likely antioxidant, xenobiotic, and heat shock elements, absent in qrd1, that probably explain the greater response of qrd2 transcription to stress. We conclude from these results that QRD1 is the enzyme G. trabeum routinely uses to detoxify quinones during incipient wood decay and that it could also drive the biodegradative quinone redox cycle. However, QRD2 assumes a more important role when the mycelium is stressed. PMID:14711659

  16. X-ray structural studies of quinone reductase 2 nanomolar range inhibitors

    SciTech Connect

    Pegan, Scott D.; Sturdy, Megan; Ferry, Gilles; Delagrange, Philippe; Boutin, Jean A.; Mesecar, Andrew D.

    2011-09-06

    Quinone reductase 2 (QR2) is one of two members comprising the mammalian quinone reductase family of enzymes responsible for performing FAD mediated reductions of quinone substrates. In contrast to quinone reductase 1 (QR1) which uses NAD(P)H as its co-substrate, QR2 utilizes a rare group of hydride donors, N-methyl or N-ribosyl nicotinamide. Several studies have linked QR2 to the generation of quinone free radicals, several neuronal degenerative diseases, and cancer. QR2 has been also identified as the third melatonin receptor (MT3) through in cellulo and in vitro inhibition of QR2 by traditional MT3 ligands, and through recent X-ray structures of human QR2 (hQR2) in complex with melatonin and 2-iodomelatonin. Several MT3 specific ligands have been developed that exhibit both potent in cellulo inhibition of hQR2 nanomolar, affinity for MT3. The potency of these ligands suggest their use as molecular probes for hQR2. However, no definitive correlation between traditionally obtained MT3 ligand affinity and hQR2 inhibition exists limiting our understanding of how these ligands are accommodated in the hQR2 active site. To obtain a clearer relationship between the structures of developed MT3 ligands and their inhibitory properties, in cellulo and in vitro IC{sub 50} values were determined for a representative set of MT3 ligands (MCA-NAT, 2-I-MCANAT, prazosin, S26695, S32797, and S29434). Furthermore, X-ray structures for each of these ligands in complex with hQR2 were determined allowing for a structural evaluation of the binding modes of these ligands in relation to the potency of MT3 ligands.

  17. Nucleic acid reactivity : challenges for next-generation semiempirical quantum models

    PubMed Central

    Huang, Ming; Giese, Timothy J.; York, Darrin M.

    2016-01-01

    Semiempirical quantum models are routinely used to study mechanisms of RNA catalysis and phosphoryl transfer reactions using combined quantum mechanical/molecular mechanical methods. Herein, we provide a broad assessment of the performance of existing semiempirical quantum models to describe nucleic acid structure and reactivity in order to quantify their limitations and guide the development of next-generation quantum models with improved accuracy. Neglect of diatomic diffierential overlap (NDDO) and self-consistent density-functional tight-binding (SCC-DFTB) semiempirical models are evaluated against high-level quantum mechanical benchmark calculations for seven biologically important data sets. The data sets include: proton affinities, polarizabilities, nucleobase dimer interactions, dimethyl phosphate anion, nucleoside sugar and glycosidic torsion conformations, and RNA phosphoryl transfer model reactions. As an additional baseline, comparisons are made with several commonly used density-functional models, including M062X and B3LYP (in some cases with dispersion corrections). The results show that, among the semiempirical models examined, the AM1/d-PhoT model is the most robust at predicting proton affinities. AM1/d-PhoT and DFTB3-3ob/OPhyd reproduce the MP2 potential energy surfaces of 6 associative RNA phosphoryl transfer model reactions reasonably well. Further, a recently developed linear-scaling “modified divide-and-conquer” model exhibits the most accurate results for binding energies of both hydrogen bonded and stacked nucleobase dimers. The semiempirical models considered here are shown to underestimate the isotropic polarizabilities of neutral molecules by approximately 30%. The semiempirical models also fail to adequately describe torsion profiles within the dimethyl phosphate anion, the nucleoside sugar ring puckers, and the rotations about the nucleoside glycosidic bond. The modeling of pentavalent phosphorus, particularly with thio

  18. Reduction of quinones and nitroaromatic compounds by Escherichia coli nitroreductase A (NfsA): Characterization of kinetics and substrate specificity.

    PubMed

    Valiauga, Benjaminas; Williams, Elsie M; Ackerley, David F; Čėnas, Narimantas

    2017-01-15

    NfsA, a major FMN-associated nitroreductase of E. coli, reduces nitroaromatic compounds via consecutive two-electron transfers. NfsA has potential applications in the biodegradation of nitroaromatic environment pollutants, e.g. explosives, and is also of interest for the anticancer strategy gene-directed enzyme prodrug therapy. However, the catalytic mechanism of NfsA is poorly characterized. Here we examined the NADPH-dependent reduction of quinones (n = 16) and nitroaromatic compounds (n = 12) by NfsA. We confirmed a general "ping-pong" reaction scheme, and preliminary rapid reaction studies of the enzyme reduction by NADPH showed that this step is much faster than the steady-state turnover number, i.e., the enzyme turnover is limited by the oxidative half-reaction. The reactivity of nitroaromatic compounds (log kcat/Km) followed a linear dependence on their single-electron reduction potential (E(1)7), indicating a limited role for compound structure or active site flexibility in their reactivity. The reactivity of quinones was lower than that of nitroaromatics having similar E(1)7 values, except for the significantly enhanced reactivity of 2-OH-1,4-naphthoquinones, consistent with observations previously made for the group B nitroreductase of Enterobacter cloacae. We present evidence that the reduction of quinones by NfsA is most consistent with a single-step (H(-)) hydride transfer mechanism.

  19. A new approach to evaluating the extent of Michael adduct formation to PAH quinones: tetramethylammonium hydroxide (TMAH) thermochemolysis with GC/MS.

    PubMed

    Briggs, Mary K; Desavis, Emmanuel; Mazzer, Paula A; Sunoj, R B; Hatcher, Susan A; Hadad, Christopher M; Hatcher, Patrick G

    2003-11-01

    Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants that are converted to cytotoxic and carcinogenic metabolites, quinones, by detoxifying enzyme systems in animals. PAH metabolites such as the quinones can form Michael adducts with biological macromolecules containing reactive nucleophiles, making detection of exposure to PAHs difficult using conventional techniques. A technique has been developed for detecting exposure to PAHs. Tetramethylammonium hydroxide (TMAH) thermochemolysis coupled with GC/MS is proposed as an assay method for PAH quinones that have formed Michael adducts with biological molecules. Three PAH quinones (1,4-naphthoquinone, 1,2-naphthoquinone, and 1,4-anthraquinone) and 1,4-benzoquinone were reacted with cysteine, and the TMAH thermochemolysis method was used to assay for both thiol and amine adduction between the quinones and the cysteine. Additional studies with 1,4-naphthoquinone adducts to glutathione and bovine serum albumin showed the same thiol and amine TMAH thermochemolysis products with larger peptides as was observed with cysteine adducts. The TMAH GC/MS method clearly shows great promise for detecting PAH quinones, produced by enzymatic conversion of PAHs in biological systems, that have been converted to respective Michael adducts.

  20. Molecular mechanism of quinone signaling mediated through S-quinonization of a YodB family repressor QsrR

    PubMed Central

    Ji, Quanjiang; Zhang, Liang; Jones, Marcus B.; Sun, Fei; Deng, Xin; Liang, Haihua; Cho, Hoonsik; Brugarolas, Pedro; Gao, Yihe N.; Peterson, Scott N.; Lan, Lefu; Bae, Taeok; He, Chuan

    2013-01-01

    Quinone molecules are intracellular electron-transport carriers, as well as critical intra- and extracellular signals. However, transcriptional regulation of quinone signaling and its molecular basis are poorly understood. Here, we identify a thiol-stress-sensing regulator YodB family transcriptional regulator as a central component of quinone stress response of Staphylococcus aureus, which we have termed the quinone-sensing and response repressor (QsrR). We also identify and confirm an unprecedented quinone-sensing mechanism based on the S-quinonization of the essential residue Cys-5. Structural characterizations of the QsrR–DNA and QsrR–menadione complexes further reveal that the covalent association of menadione directly leads to the release of QsrR from operator DNA following a 10° rigid-body rotation as well as a 9-Å elongation between the dimeric subunits. The molecular level characterization of this quinone-sensing transcriptional regulator provides critical insights into quinone-mediated gene regulation in human pathogens. PMID:23479646

  1. A copper-induced quinone degradation pathway provides protection against combined copper/quinone stress in Lactococcus lactis IL1403.

    PubMed

    Mancini, Stefano; Abicht, Helge K; Gonskikh, Yulia; Solioz, Marc

    2015-02-01

    Quinones are ubiquitous in the environment. They occur naturally but are also in widespread use in human and industrial activities. Quinones alone are relatively benign to bacteria, but in combination with copper, they become toxic by a mechanism that leads to intracellular thiol depletion. Here, it was shown that the yahCD-yaiAB operon of Lactococcus lactis IL1403 provides resistance to combined copper/quinone stress. The operon is under the control of CopR, which also regulates expression of the copRZA copper resistance operon as well as other L. lactis genes. Expression of the yahCD-yaiAB operon is induced by copper but not by quinones. Two of the proteins encoded by the operon appear to play key roles in alleviating quinone/copper stress: YaiB is a flavoprotein that converts p-benzoquinones to less toxic hydroquinones, using reduced nicotinamide adenine dinucleotide phosphate (NADPH) as reductant; YaiA is a hydroquinone dioxygenase that converts hydroquinone putatively to 4-hydroxymuconic semialdehyde in an oxygen-consuming reaction. Hydroquinone and methylhydroquinone are both substrates of YaiA. Deletion of yaiB causes increased sensitivity of L. lactis to quinones and complete growth arrest under combined quinone and copper stress. Copper induction of the yahCD-yaiAB operon offers protection to copper/quinone toxicity and could provide a growth advantage to L. lactis in some environments.

  2. Control of Reactive Species Generated by Low-frequency Biased Nanosecond Pulse Discharge in Atmospheric Pressure Plasma Effluent

    NASA Astrophysics Data System (ADS)

    Takashima, Keisuke; Kaneko, Toshiro

    2016-09-01

    The control of hydroxyl radical and the other gas phase species generation in the ejected gas through air plasma (air plasma effluent) has been experimentally studied, which is a key to extend the range of plasma treatment. Nanosecond pulse discharge is known to produce high reduced electric field (E/N) discharge that leads to efficient generation of the reactive species than conventional low frequency discharge, while the charge-voltage cycle in the low frequency discharge is known to be well-controlled. In this study, the nanosecond pulse discharge biased with AC low frequency high voltage is used to take advantages of these discharges, which allows us to modulate the reactive species composition in the air plasma effluent. The utilization of the gas-liquid interface and the liquid phase chemical reactions between the modulated long-lived reactive species delivered from the air plasma effluent could realize efficient liquid phase chemical reactions leading to short-lived reactive species production far from the air plasma, which is crucial for some plasma agricultural applications.

  3. Procyanidins from Nelumbo nucifera Gaertn. Seedpod induce autophagy mediated by reactive oxygen species generation in human hepatoma G2 cells.

    PubMed

    Duan, Yuqing; Xu, Hui; Luo, Xiaoping; Zhang, Haihui; He, Yuanqing; Sun, Guibo; Sun, Xiaobo

    2016-04-01

    In this study, autophagic effect of procyanidins from lotus (Nelumbo nucifera Gaertn.) seedpod (LSPCs) on human hepatoma G2 (HepG2) cells, and the inherent correlation between autophagic levels and reactive oxygen species (ROS) generation were investigated. The results showed that LSPCs increased monodansylcadaverine (MDC) fluorescence intensity and LC3-I/LC3-II conversion in HepG2 cells. In addition, the typically autophagic characteristics (autophagosomes and autolysosomes) were observed in LSPCs-treated cells, but not found in the cells treated with autophagy inhibitor 3-methyladenine (3-MA). Furthermore, the elevated ROS level was in line with the increasing of autophagy activation caused by LSPCs, however, both 3-MA and the ROS scavenger N-acetylcyteine (NAC) inhibitors effectively suppressed the autophagy and ROS generation triggered by LSPCs. As a result, these results indicated that LSPCs induced HepG2 cell autophagy in a time- and dose-dependent manner, and promoted reactive oxygen species (ROS) generation on HepG2 cells. Moreover, we found that LSPCs caused DNA damage, S phase arrest and the decrement of mitochondria membrane potential (MMP) which were associated with ROS generation. In summary, our findings demonstrated that the LSPCs-induced autophagy and autophagic cell death were triggered by the ROS generation in HepG2 cells, which might be associated with ROS generation through the mitochondria-dependent signaling way. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  4. Quenching of chlorophyll fluorescence by quinones.

    PubMed

    Samuilov, V D; Borisov AYu; Barsky, E L; Borisova, O F; Kitashov, A V

    1998-10-01

    Quinones caused quenching of Chl a fluorescence in native and model systems. Menadione quenched twofold the fluorescence of Chl a and BChl a in pea chloroplasts, chromatophores of purple bacteria, and liposomes at concentrations of 50-80 microM. To obtain twofold quenching in Triton X-100 micelles and in ethanol, the addition of 1.3 mM and 11 mM menadione was required, respectively. A proportional decrease in the lifetime and yield of Chl a fluorescence in chloroplasts, observed as the menadione concentration increased, is indicative of the efficient excitation energy transfer from bulk Chl to menadione. The decrease in the lifetime and yield of fluorescence was close to proportional in liposomes, but not in detergent micelles. The insensitivity of the menadione quenching effect to DCMU in chloroplasts, and similarity of its action in chloroplasts and liposomes indicate that menadione in chloroplasts interacts with antenna Chl, i.e., nonphotochemical quenching of fluorescence occurs.

  5. Chemoselective methylation of phenolic hydroxyl group prevents quinone methide formation and repolymerization during lignin depolymerization

    DOE PAGES

    Kim, Kwang Ho; Dutta, Tanmoy; Walter, Eric D.; ...

    2017-03-22

    Chemoselective blocking of the phenolic hydroxyl (Ar–OH) group by methylation was found to suppress secondary repolymerization and charring during lignin depolymerization. Methylation of Ar–OH prevents formation of reactive quinone methide intermediates, which are partly responsible for undesirable secondary repolymerization reactions. Instead, this structurally modified lignin produces more relatively low molecular weight products from lignin depolymerization compared to unmodified lignin. This result demonstrates that structural modification of lignin is desirable for production of low molecular weight phenolic products. Finally, this approach could be directed toward alteration of natural lignification processes to produce biomass that is more amenable to chemical depolymerization.

  6. NAD(P)H quinone oxidoreductase 1 regulates neutrophil elastase-induced mucous cell metaplasia

    PubMed Central

    Meyer, Marisa L.; Potts-Kant, Erin N.; Ghio, Andrew J.; Fischer, Bernard M.; Foster, W. Michael

    2012-01-01

    Mucous cell metaplasia (MCM) and neutrophil-predominant airway inflammation are pathological features of chronic inflammatory airway diseases. A signature feature of MCM is increased expression of a major respiratory tract mucin, MUC5AC. Neutrophil elastase (NE) upregulates MUC5AC in primary airway epithelial cells by generating reactive oxygen species, and this response is due in part to upregulation of NADPH quinone oxidoreductase 1 (NQO1) activity. Delivery of NE directly to the airway triggers inflammation and MCM and increases synthesis and secretion of MUC5AC protein from airway epithelial cells. We hypothesized that NE-induced MCM is mediated in vivo by NQO1. Male wild-type and Nqo1-null mice (C57BL/6 background) were exposed to human NE (50 μg) or vehicle via oropharyngeal aspiration on days 1, 4, and 7. On days 8 and 11, lung tissues and bronchoalveolar lavage (BAL) samples were obtained and evaluated for MCM, inflammation, and oxidative stress. MCM, inflammation, and production of specific cytokines, granulocyte-macrophage colony-stimulating factor, macrophage inflammatory protein-2, interleukin-4, and interleukin-5 were diminished in NE-treated Nqo1-null mice compared with NE-treated wild-type mice. However, in contrast to the role of NQO1 in vitro, we demonstrate that NE-treated Nqo1-null mice had greater levels of BAL and lung tissue lipid carbonyls and greater BAL iron on day 11, all consistent with increased oxidative stress. NQO1 is required for NE-induced inflammation and MCM. This model system demonstrates that NE-induced MCM directly correlates with inflammation, but not with oxidative stress. PMID:22659878

  7. From Microbiology to Cancer Biology: The Rid Protein Family Prevents Cellular Damage Caused by Endogenously Generated Reactive Nitrogen Species

    PubMed Central

    Downs, Diana M.; Ernst, Dustin C.

    2015-01-01

    Summary The Rid family of proteins is highly conserved and broadly distributed throughout the domains of life. Genetic and biochemical studies, primarily in Salmonella enterica, have defined a role for RidA in responding to endogenously generated reactive metabolites. The data show that 2-aminoacrylate (2AA), a reactive enamine intermediate generated by some pyridoxal 5′-phosphate (PLP)-dependent enzymes, accumulates in the absence of RidA. The accumulation of 2AA leads to covalent modification and inactivation of several enzymes involved in essential metabolic processes. This review describes the 2AA hydrolyzing activity of RidA and the effect of this biochemical activity on the metabolic network, which impacts organism fitness. The reported activity of RidA and the consequences encountered in vivo when RidA is absent have challenged fundamental assumptions in enzymology, biochemistry and cell metabolism regarding the fate of transiently-generated reactive enamine intermediates. The current understanding of RidA in Salmonella and the broad distribution of Rid family proteins provide exciting opportunities for future studies to define metabolic roles of Rid family members from microbes to man. PMID:25620221

  8. From microbiology to cancer biology: the Rid protein family prevents cellular damage caused by endogenously generated reactive nitrogen species.

    PubMed

    Downs, Diana M; Ernst, Dustin C

    2015-04-01

    The Rid family of proteins is highly conserved and broadly distributed throughout the domains of life. Genetic and biochemical studies, primarily in Salmonella enterica, have defined a role for RidA in responding to endogenously generated reactive metabolites. The data show that 2-aminoacrylate (2AA), a reactive enamine intermediate generated by some pyridoxal 5'-phosphate-dependent enzymes, accumulates in the absence of RidA. The accumulation of 2AA leads to covalent modification and inactivation of several enzymes involved in essential metabolic processes. This review describes the 2AA hydrolyzing activity of RidA and the effect of this biochemical activity on the metabolic network, which impacts organism fitness. The reported activity of RidA and the consequences encountered in vivo when RidA is absent have challenged fundamental assumptions in enzymology, biochemistry and cell metabolism regarding the fate of transiently generated reactive enamine intermediates. The current understanding of RidA in Salmonella and the broad distribution of Rid family proteins provide exciting opportunities for future studies to define metabolic roles of Rid family members from microbes to man. © 2015 John Wiley & Sons Ltd.

  9. Structure-reactivity relationships of flavan-3-ols on product generation in aqueous glucose/glycine model systems.

    PubMed

    Noda, Yuko; Peterson, Devin G

    2007-05-02

    Ring structure-reactivity relationships of three flavan-3-ols [epicatechin (EC), epicatechin gallate (ECG), and epigallocatechin gallate (EGCG)] and three simple phenolic compounds (1,3,5-trihydroxybenzene, 1,2,3-trihydroxybenzene, and methylgallate as the analogous individual A, B, and C benzene rings of EGCG) on product generation in an aqueous glucose-glycine reaction model system (125 degrees C and 30 min) were investigated. The addition of EC, ECG, or EGCG to a glucose-glycine model was reported to similarly significantly reduce the formation of pyrazine, methyl-substituted pyrazines, and cyclotene. All three flavan-3-ols were also reported to generate phenolic-C2, C3, C4, and C6 sugar fragment adducts and to statistically reduce the concentration of glyoxal, glycolaldehyde, methylglyoxal, hydroxyacetone, diacetyl, acetoin, and 3-deoxyglucosone during the reaction time course, except for the EGCG reaction where 3-deoxyglucosone was not statistically different from the control after 20 min. For the simple phenolic compounds, methylgallate followed by 1,2,3-trihydroxybenzene was the least reactive, while 1,3,5-trihydroxybenzene was reported as the most reactive phenolic structure for quenching or reducing the concentration of the alpha-hydroxy- and alpha-dicarbonyl sugar fragments during the reaction time course. These results imply that the main mechanism flavan-3-ols reduced product generation was phenolic-sugar fragment carbonyl trapping reactions primarily on the A ring (the meta-polyhydroxylated benzene ring) or not due to the alteration of the reaction reduction potential.

  10. Flow cytometric assessment of reactive oxygen species generations that are directly related to cellular ZnO nanoparticle uptake.

    PubMed

    Yoo, Hyun Ju; Yoon, Tae Hyun

    2014-07-01

    In this study, a simple flow cytometry protocol to evaluate nanoparticle associated biological response was proposed. Particularly, we have evaluated the effect of surface charge on the cellular nanoparticle associations and nanoparticle-induced apoptosis. Significant enhancement in side scattering intensity was observed for the HeLa cells treated with positively charged (PLL)ZnO nanoparticles, suggesting that the (PLL)ZnO nanoparticles may induce cell death via adsorption and endocytosis of the nanoparticles. On the other hand, the negatively charged (PAA)ZnO nanoparticle seems to cause cell death process indirectly via the released Zn ions, with less contribution from cellular association of nanoparticles. Time- and dose-dependent studies on cellular association of ZnO nanoparticles, and ZnO associated reactive oxygen species generation were also performed for the HeLa cells exposed to the (PLL)ZnO nanoparticle. For those cells associated with (PLL)ZnO nanoparticle, a significant enhancement in reactive oxygen species generation was observed even at a lower concentration (10 ppm), which was not observable for the results with the whole cell population. By using this approach, we are able to distinguish biological responses (e.g., reactive oxygen species (ROS) generation) directly related to the cellular associations of NPs from those indirectly related to the cellular associations of NPs, such as the cytotoxicity caused by the NP released metal ions.

  11. Structure-function studies of the photosynthetic reaction center using herbicides that compete for the quinone binding site

    SciTech Connect

    Bylina, E.J.

    1995-12-31

    Certain classes of herbicides act as competitive inhibitors of the photosynthetic reaction center. Genetic engineering techniques can be used to generate photosynthetic reaction centers which contain altered quinone binding sites. A genetic system for rapidly screening herbicides developed in the photosynthetic bacterium Rhodobacter capsulatus has been used to examine the effect of different s-triazine herbicides on the growth of bacteria containing reaction centers with altered quinone binding sites. Structural insights into herbicide binding have been obtained by determining the level of resistance or sensitivity to structurally related herbicides in these modified reaction centers.

  12. Synergistic Rhodium/Phosphoric Acid Catalysis for the Enantioselective Addition of Oxonium Ylides to ortho-Quinone Methides.

    PubMed

    Alamsetti, Santosh Kumar; Spanka, Matthias; Schneider, Christoph

    2016-02-12

    We report herein a powerful and highly stereoselective protocol for the domino-type reaction of diazoesters with ortho-quinone methides generated in situ to furnish densely functionalized chromans with three contiguous stereogenic centers. A transition-metal and a Brønsted acid catalyst were shown to act synergistically to produce a transient oxonium ylide and ortho-quinone methide, respectively, in two distinct cycles. These intermediates underwent subsequent coupling in a conjugate-addition-hemiacetalization event in generally good yield with excellent diastereo- and enantioselectivity.

  13. The effect of the copper chelator tetraethylenepentamine on reactive oxygen species generation by human hematopoietic progenitor cells.

    PubMed

    Prus, Eugenia; Fibach, Eitan

    2007-12-01

    Clinical observations suggest that copper (Cu) plays a role in regulating hematopoietic progenitor cell (HPC) development. Cu is known to generate oxidative stress in cells which in turn affects proliferation, differentiation and apoptosis. To study this role of Cu, we used double staining flow cytometry to measure reactive oxygen species (ROS) generation by neonatal cord blood-derived CD34(+)CD38(-) cells. ROS was increased by Cu and was decreased by the Cu chelator tetraethylenepentamine (TEPA). Previously, we showed that TEPA reduces the free Cu content of HPCs and stimulates their ex vivo expansion. The present results suggest that TEPA affects expansion of HPCs by lowering their oxidative stress.

  14. LC/MSMS STUDY OF BENZO[A]PYRENE-7,8-QUINONE ADDUCTION TO GLOBIN TRYPTIC PEPTIDES AND N-ACETYLAMINO ACIDS

    EPA Science Inventory

    Benzo[a]pyrene-7,8-quinone (BPQ) is regarded as a reactive genotoxic compound enzymatically formed from a xenobiotic precursor benzo[a]pyrene-7,8-diol by aldo-keto-reductase family of enzymes. Because BPQ, a Michael electrophile, was previously shown to react with oligonucleotide...

  15. LC/MSMS STUDY OF BENZO[A]PYRENE-7,8-QUINONE ADDUCTION TO GLOBIN TRYPTIC PEPTIDES AND N-ACETYLAMINO ACIDS

    EPA Science Inventory

    Benzo[a]pyrene-7,8-quinone (BPQ) is regarded as a reactive genotoxic compound enzymatically formed from a xenobiotic precursor benzo[a]pyrene-7,8-diol by aldo-keto-reductase family of enzymes. Because BPQ, a Michael electrophile, was previously shown to react with oligonucleotide...

  16. NMR Reveals Double Occupancy of Quinone-type Ligands in the Catalytic Quinone Binding Site of the Na+-translocating NADH:Quinone Oxidoreductase from Vibrio cholerae*

    PubMed Central

    Nedielkov, Ruslan; Steffen, Wojtek; Steuber, Julia; Möller, Heiko M.

    2013-01-01

    The sodium ion-translocating NADH:quinone oxidoreductase (Na+-NQR) from the pathogen Vibrio cholerae exploits the free energy liberated during oxidation of NADH with ubiquinone to pump sodium ions across the cytoplasmic membrane. The Na+-NQR consists of four membrane-bound subunits NqrBCDE and the peripheral NqrF and NqrA subunits. NqrA binds ubiquinone-8 as well as quinones with shorter prenyl chains (ubiquinone-1 and ubiquinone-2). Here we show that the quinone derivative 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB), a known inhibitor of the bc1 and b6f complexes found in mitochondria and chloroplasts, also inhibits quinone reduction by the Na+-NQR in a mixed inhibition mode. Tryptophan fluorescence quenching and saturation transfer difference NMR experiments in the presence of Na+-NQR inhibitor (DBMIB or 2-n-heptyl-4-hydroxyquinoline N-oxide) indicate that two quinone analog ligands are bound simultaneously by the NqrA subunit with very similar interaction constants as observed with the holoenzyme complex. We conclude that the catalytic site of quinone reduction is located on NqrA. The two ligands bind to an extended binding pocket in direct vicinity to each other as demonstrated by interligand Overhauser effects between ubiquinone-1 and DBMIB or 2-n-heptyl-4-hydroxyquinoline N-oxide, respectively. We propose that a similar spatially close arrangement of the native quinone substrates is also operational in vivo, enhancing the catalytic efficiency during the final electron transfer steps in the Na+-NQR. PMID:24003222

  17. Thioredoxin-2 inhibits mitochondrial reactive oxygen species generation and apoptosis stress kinase-1 activity to maintain cardiac function.

    PubMed

    Huang, Qunhua; Zhou, Huanjiao Jenny; Zhang, Haifeng; Huang, Yan; Hinojosa-Kirschenbaum, Ford; Fan, Peidong; Yao, Lina; Belardinelli, Luiz; Tellides, George; Giordano, Frank J; Budas, Grant R; Min, Wang

    2015-03-24

    Thioredoxin 2 (Trx2) is a key mitochondrial protein that regulates cellular redox and survival by suppressing mitochondrial reactive oxygen species generation and by inhibiting apoptosis stress kinase-1 (ASK1)-dependent apoptotic signaling. To date, the role of the mitochondrial Trx2 system in heart failure pathogenesis has not been investigated. Western blot and histological analysis revealed that Trx2 protein expression levels were reduced in hearts from patients with dilated cardiomyopathy, with a concomitant increase in ASK1 phosphorylation/activity. Cardiac-specific Trx2 knockout mice develop spontaneous dilated cardiomyopathy at 1 month of age with increased heart size, reduced ventricular wall thickness, and a progressive decline in left ventricular contractile function, resulting in mortality due to heart failure by ≈4 months of age. The progressive decline in cardiac function observed in cardiac-specific Trx2 knockout mice was accompanied by the disruption of mitochondrial ultrastructure, mitochondrial membrane depolarization, increased mitochondrial reactive oxygen species generation, and reduced ATP production, correlating with increased ASK1 signaling and increased cardiomyocyte apoptosis. Chronic administration of a highly selective ASK1 inhibitor improved cardiac phenotype and reduced maladaptive left ventricular remodeling with significant reductions in oxidative stress, apoptosis, fibrosis, and cardiac failure. Cellular data from Trx2-deficient cardiomyocytes demonstrated that ASK1 inhibition reduced apoptosis and reduced mitochondrial reactive oxygen species generation. Our data support an essential role for mitochondrial Trx2 in preserving cardiac function by suppressing mitochondrial reactive oxygen species production and ASK1-dependent apoptosis. Inhibition of ASK1 represents a promising therapeutic strategy for the treatment of dilated cardiomyopathy and heart failure. © 2015 American Heart Association, Inc.

  18. Oxidation of various reactive dyes with in situ electro-generated active chlorine for textile dyeing industry wastewater treatment.

    PubMed

    Rajkumar, D; Kim, Jong Guk

    2006-08-21

    The present investigation revealed that all the reactive dyes were degraded in chlorine mediated electrochemical oxidation. Titanium based dimensionally stable anode (DSA) was used for in situ generation of chlorine in the dye solution. All classes of reactive dyes (100 mg/L) showed a complete color removal at a supporting electrolyte concentration of 1.5 g/L NaCl and 36.1 mA/cm(2) current density. The chemical oxygen demand (COD) and total organic carbon (TOC) removals were from 39.5 to 82.8% and from 11.3 to 44.7%, respectively, for different reactive dyes. It can be concluded in general that the triazine containing higher molecular weight diazo compounds takes more time for complete de-colorization than the mono azo or anthraquinone containing dye compounds. The degradation rate of mixed dye compounds was affected by reaction temperature, current density, NaCl concentration and initial dye concentration. However, the initial pH of the dye solution ranging from 4.3 to 9.4 did not show significant effect on de-colorization. A complete color removal with 73.5% COD and 32.8% TOC removals were obtained for mixed reactive dyes (200 mg/L) at the end of 120 min of electrolysis under the optimum operating conditions of 4 g/L NaCl concentration and 72.2 mA/cm(2) current density.

  19. Oxidation of 3,4-dihydroxyphenylacetaldehyde, a toxic dopaminergic metabolite, to a semiquinone radical and an ortho-quinone.

    PubMed

    Anderson, David G; Mariappan, S V Santhana; Buettner, Garry R; Doorn, Jonathan A

    2011-07-29

    The oxidation and toxicity of dopamine is believed to contribute to the selective neurodegeneration associated with Parkinson disease. The formation of reactive radicals and quinones greatly contributes to dopaminergic toxicity through a variety of mechanisms. The physiological metabolism of dopamine to 3,4-dihydroxyphenylacetaldehyde (DOPAL) via monoamine oxidase significantly increases its toxicity. To more adequately explain this enhanced toxicity, we hypothesized that DOPAL is capable of forming radical and quinone species upon oxidation. Here, two unique oxidation products of DOPAL are identified. Several different oxidation methods gave rise to a transient DOPAL semiquinone radical, which was characterized by electron paramagnetic resonance spectroscopy. NMR identified the second oxidation product of DOPAL as the ortho-quinone. Also, carbonyl hydration of DOPAL in aqueous media was evident via NMR. Interestingly, the DOPAL quinone exists exclusively in the hydrated form. Furthermore, the enzymatic and chemical oxidation of DOPAL greatly enhance protein cross-linking, whereas auto-oxidation results in the production of superoxide. Also, DOPAL was shown to be susceptible to oxidation by cyclooxygenase-2 (COX-2). The involvement of this physiologically relevant enzyme in both oxidative stress and Parkinson disease underscores the potential importance of DOPAL in the pathogenesis of this condition.

  20. Quinones as dienophiles in the Diels-Alder reaction: history and applications in total synthesis.

    PubMed

    Nawrat, Christopher C; Moody, Christopher J

    2014-02-17

    In the canon of reactions available to the organic chemist engaged in total synthesis, the Diels-Alder reaction is among the most powerful and well understood. Its ability to rapidly generate molecular complexity through the simultaneous formation of two carbon-carbon bonds is almost unrivalled, and this is reflected in the great number of reported applications of this reaction. Historically, the use of quinones as dienophiles is highly significant, being the very first example investigated by Diels and Alder. Herein, we review the application of the Diels-Alder reaction of quinones in the total synthesis of natural products. The highlighted examples span some 60 years from the landmark syntheses of morphine (1952) and reserpine (1956) by Gates and Woodward, respectively, through to the present day examples, such as the tetracyclines. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. [Quinones and their interactions with enzyme complexes of energy-transducing biomembranes].

    PubMed

    Oleskin, A V; Samuilov, V D

    1988-10-01

    The functionally essential properties of biomembrane quinones and the mechanism of their interaction with protein components are discussed. The hypotheses on the mobile quinone pool or the ability of protein-bound quinones to transfer redox equivalents in biomembranes are discussed. The idea of quinone domains is invoked, and evidence is provided for the presence of such domains in operative biomembranes.

  2. Lysophosphatidic acid induces reactive oxygen species generation by activating protein kinase C in PC-3 human prostate cancer cells

    SciTech Connect

    Lin, Chu-Cheng; Lin, Chuan-En; Lin, Yueh-Chien; Ju, Tsai-Kai; Huang, Yuan-Li; Lee, Ming-Shyue; Chen, Jiun-Hong; Lee, Hsinyu

    2013-11-01

    Highlights: •LPA induces ROS generation through LPA{sub 1} and LPA{sub 3}. •LPA induces ROS generation by activating PLC. •PKCζ mediates LPA-induced ROS generation. -- Abstract: Prostate cancer is one of the most frequently diagnosed cancers in males, and PC-3 is a cell model popularly used for investigating the behavior of late stage prostate cancer. Lysophosphatidic acid (LPA) is a lysophospholipid that mediates multiple behaviors in cancer cells, such as proliferation, migration and adhesion. We have previously demonstrated that LPA enhances vascular endothelial growth factor (VEGF)-C expression in PC-3 cells by activating the generation of reactive oxygen species (ROS), which is known to be an important mediator in cancer progression. Using flow cytometry, we showed that LPA triggers ROS generation within 10 min and that the generated ROS can be suppressed by pretreatment with the NADPH oxidase (Nox) inhibitor diphenylene iodonium. In addition, transfection with LPA{sub 1} and LPA{sub 3} siRNA efficiently blocked LPA-induced ROS production, suggesting that both receptors are involved in this pathway. Using specific inhibitors and siRNA, phospholipase C (PLC) and protein kinase C (PKC) were also suggested to participate in LPA-induced ROS generation. Overall, we demonstrated that LPA induces ROS generation in PC-3 prostate cancer cells and this is mediated through the PLC/PKC/Nox pathway.

  3. Lifespan extension by peroxidase and dual oxidase-mediated ROS signaling through pyrroloquinoline quinone in C. elegans.

    PubMed

    Sasakura, Hiroyuki; Moribe, Hiroki; Nakano, Masahiko; Ikemoto, Kazuto; Takeuchi, Kosei; Mori, Ikue

    2017-08-01

    Reactive oxygen species (ROS), originally characterized based on their harmful effects on cells or organisms, are now recognized as important signal molecules regulating various biological processes. In particular, low levels of ROS released from mitochondria extend lifespan. Here, we identified a novel mechanism of generating appropriate levels of ROS at the plasma membrane through a peroxidase and dual oxidase (DUOX) system, which could extend lifespan in Caenorhabditis elegans A redox co-factor, pyrroloquinoline quinone (PQQ), activates the C. elegans DUOX protein BLI-3 to produce the ROS H2O2 at the plasma membrane, which is subsequently degraded by peroxidase (MLT-7), eventually ensuring adequate levels of ROS. These ROS signals are transduced mainly by the oxidative stress transcriptional factors SKN-1 (Nrf2 or NFE2L2 in mammals) and JUN-1, and partially by DAF-16 (a FOXO protein homolog). Cell biology experiments demonstrated a similarity between the mechanisms of PQQ-induced activation of human DUOX1 and DUOX2 and that of C. elegans BLI-3, suggesting that DUOXs are potential targets of intervention for lifespan extension. We propose that low levels of ROS, fine-tuned by the peroxidase and dual oxidase system at the plasma membrane, act as second messengers to extend lifespan by the effect of hormesis. © 2017. Published by The Company of Biologists Ltd.

  4. The HemQ coprohaem decarboxylase generates reactive oxygen species: implications for the evolution of classical haem biosynthesis

    PubMed Central

    Hobbs, Charlie; Dailey, Harry A.; Shepherd, Mark

    2016-01-01

    Bacteria require a haem biosynthetic pathway for the assembly of a variety of protein complexes, including cytochromes, peroxidases, globins, and catalase. Haem is synthesised via a series of tetrapyrrole intermediates, including non-metallated porphyrins, such as protoporphyrin IX, which is well known to generate reactive oxygen species in the presence of light and oxygen. Staphylococcus aureus has an ancient haem biosynthetic pathway that proceeds via the formation of coproporphyrin III, a less reactive porphyrin. Here, we demonstrate, for the first time, that HemY of S. aureus is able to generate both protoporphyrin IX and coproporphyrin III, and that the terminal enzyme of this pathway, HemQ, can stimulate the generation of protoporphyrin IX (but not coproporphyrin III). Assays with hydrogen peroxide, horseradish peroxidase, superoxide dismutase, and catalase confirm that this stimulatory effect is mediated by superoxide. Structural modelling reveals that HemQ enzymes do not possess the structural attributes that are common to peroxidases that form compound I [FeIV==O]+, which taken together with the superoxide data leaves Fenton chemistry as a likely route for the superoxide-mediated stimulation of protoporphyrinogen IX oxidase activity of HemY. This generation of toxic free radicals could explain why HemQ enzymes have not been identified in organisms that synthesise haem via the classical protoporphyrin IX pathway. This work has implications for the divergent evolution of haem biosynthesis in ancestral microorganisms, and provides new structural and mechanistic insights into a recently discovered oxidative decarboxylase reaction. PMID:27597779

  5. Electrochemical generation and reactivity of free radical redox intermediates from ortho- and meta-nitro substituted 1,4-dihydropyridines.

    PubMed

    Núñez-Vergara, L J; Ortiz, M E; Bollo, S; Squella, J A

    1997-08-29

    This paper reports a comprehensive study by cyclic voltammetry on the electrochemical characteristics and the reactivity of the one-electron reduction product from a series of nitro aryl 1,4-dihydropyridines in mixed and aprotic media. In addition, the effects of 1,4-DHP on the oxygen consumption of T. cruzi epimastigotes are reported. One-electron reduction products from 1,4-DHP derivatives significantly reacted with both thiol compounds and the nuclei acid bases, adenine and uracil. This reactivity was significantly higher than the natural decay of the radicals in mixed media. Based on these results the following tentative order of reactivity towards the xeno/endobiotics is as follows: cysteamine > glutathione > adenineuracil. Both the stability and the reactivity of the nitro radical anions electrochemically generated from 1,4-DHP showed a linear dependence with pH. The sensitivity to pH of the radicals derived from o-nitro substituted derivatives was significantly higher than m-nitro substituted derivatives. On the other hand, in all cases an increase of pH produced a significant decrease in the interaction rate constant. Interaction studies carried out in aprotic media did not show any reactivity of the radicals towards both thiol compounds and the nuclei acid bases, adenine and uracil. Therefore, we concluded that the interaction process requires certain proton activity in the media. All the tested 1,4-dihydropyridines inhibited the oxygen consumption by T. cruzi epimastigotes, Tulahuén strain. The drugs with higher electron-affinity produced greater inhibition than those with lower electron-affinity (i.e. nicardipine vs nifedipine).

  6. Characterization of the quinones in purple sulfur bacterium Thermochromatium tepidum.

    PubMed

    Kimura, Yuuka; Kawakami, Tomoaki; Yu, Long-Jiang; Yoshimura, Miku; Kobayashi, Masayuki; Wang-Otomo, Zheng-Yu

    2015-07-08

    Quinone distributions in the thermophilic purple sulfur bacterium Thermochromatium tepidum have been investigated at different levels of the photosynthetic apparatus. Here we show that, on average, the intracytoplasmic membrane contains 18 ubiquinones (UQ) and 4 menaquinones (MQ) per reaction center (RC). About one-third of the quinones are retained in the light-harvesting-reaction center core complex (LH1-RC) with a similar ratio of UQ to MQ. The numbers of quinones essentially remains unchanged during crystallization of the LH1-RC. There are 1-2 UQ and 1 MQ associated with the RC-only complex in the purified solution sample. Our results suggest that a large proportion of the quinones are confined to the core complex and at least five UQs remain invisible in the current LH1-RC crystal structure. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

  7. A Reactive-Heat-Pipe for Combined Heat Generation and Transport

    DTIC Science & Technology

    1977-12-01

    Pumping Heights for Different Temperatures. . . 70 22 Effect of Flow Losses on System Thermal Performance with No Argon in the Condenser...73 23 Flow Losses in the Vapor Transport System with Argon in the Condenser ................... 75 24 Temperature Distributions in a Reactive-Heat...shroud flow of inert gas, usually argon. The inert gas is recirculated through a vent system . The outer shroud flow prevents the direct contact

  8. Evaluation of Antibacterial Activity and Reactive Species Generation of N-Benzenesulfonyl Derivatives of Heterocycles.

    PubMed

    Martínez, Sol Romina; Miana, Gisele Emilse; Albesa, Inés; Mazzieri, María Rosa; Becerra, María Cecilia

    2016-01-01

    Two N-benzenesulfonyl (BS) derivatives of 1,2,3,4-tetrahydroquinoline (THQ) were designed, prepared, and screened for antibacterial activity. This approach was based on combining the two privileged structures, BS and THQ, which are known to be active. The objective of this study was to evaluate the antibacterial activity of BS-THQ and its analogue 4-NH2BS-THQ, and to investigate the roles of reactive oxygen species and reactive nitrogen species in their lethality. Both showed bactericidal activity against Staphylococcus aureus ATCC 29213 and methicillin-resistant S. aureus (MRSA) ATCC 43300, with transmission electron microscopy revealing a disturbed membrane architecture. Furthermore, an increase of reactive oxygen species (ROS) in strains treated with BS-THQ with respect to the control was detected when fluorescent microscopy and spectrophotometric techniques were used. The analogue 4-NH2BS-THQ demonstrated a broader spectrum of activity than BS-THQ, with a minimum inhibitory concentration of 100 µg/mL against reference strains of S. aureus, Escherichia coli and Pseudomonas aeruginosa. The assayed compounds represent promising structures for the development of new synthetic classes of antimicrobials.

  9. Reactivity of oxygen generated by carbon dioxide in heterogeneous catalytic oxidation of organic substances of various classes

    SciTech Connect

    Mirzabekova, S.R.; Mamedov, A.Kh.; Rustamov, M.I.

    1995-01-01

    Reactivity of oxygen, generated by carbon dioxide, is studied in oxidation of organic substances of various classes. It is found that oxygen, generated during CO{sub 2} reduction, may participate in both partial oxidation and dehydrogenation or cracking. A different action of oxygen produced from O{sub 2} and CO{sub 2} is assumed. Two types of interactions between organic substances and CO{sub 2} presumably exist: the first type involves surface carbonates, whereas interaction of the second type proceeds via the reduction of the catalyst surface that has been previously oxidized by carbon dioxide. Oxygen, generated by CO{sub 2}, is readily removed during the catalyst reduction with hydrocarbons.

  10. Electrophilic Aldehydes Generated by Sperm Metabolism Activate Mitochondrial Reactive Oxygen Species Generation and Apoptosis by Targeting Succinate Dehydrogenase*

    PubMed Central

    Aitken, R. John; Whiting, Sara; De Iuliis, Geoffry N.; McClymont, Samantha; Mitchell, Lisa A.; Baker, Mark A.

    2012-01-01

    Oxidative stress is a major cause of defective sperm function in cases of male infertility. Such stress is known to be associated with high levels of superoxide production by the sperm mitochondria; however, the causes of this aberrant activity are unknown. Here we show that electrophilic aldehydes such as 4-hydroxynonenal (4HNE) and acrolein, generated as a result of lipid peroxidation, target the mitochondria of human spermatozoa and stimulate mitochondrial superoxide generation in a dose- and time-dependent manner. The activation of mitochondrial electron leakage by 4HNE is shown to involve the disruption of succinate dehydrogenase activity and subsequent activation of an intrinsic apoptotic cascade beginning with a loss of mitochondrial membrane potential and terminating in oxidative DNA adduct formation, DNA strand breakage, and cell death. A tight correlation between spontaneous mitochondrial superoxide generation and 4HNE content (R2 = 0.89) in untreated populations of human spermatozoa emphasized the pathophysiological significance of these findings. The latter also provide a biochemical explanation for the self-perpetuating nature of oxidative stress in the male germ line, with the products of lipid peroxidation stimulating free radical generation by the sperm mitochondria in a positive feedback loop. PMID:22851170

  11. Production and Radioprotective Effects of Pyrroloquinoline Quinone

    PubMed Central

    Xiong, Xiang-Hua; Zhao, Yan; Ge, Xin; Yuan, Shou-Jun; Wang, Jian-Hua; Zhi, Jing-Juan; Yang, Yan-Xin; Du, Bao-Hua; Guo, Wan-Jun; Wang, Shan-Shan; Yang, De-Xuan; Zhang, Wei-Cai

    2011-01-01

    Pyrroloquinoline quinone (PQQ) was produced by fermentation of the Methylovorus sp. MP688 strain and purified by ion-exchange chromatography, crystallization and recrystallization. The yield of PQQ reached approximately 125 mg/L and highly pure PQQ was obtained. To determine the optimum dose of PQQ for radioprotection, three doses (2 mg/kg, 4 mg/kg, 8 mg/kg) of PQQ were orally administrated to the experimental animals subjected to a lethal dose of 8.0 Gy in survival test. Survival of mice in the irradiation + PQQ (4 mg/kg) group was found to be significantly higher in comparison with the irradiation and irradiation + nilestriol (10 mg/kg) groups. The numbers of hematocytes and bone marrow cells were measured for 21 days after sublethal 4 Gy gamma-ray irradiation with per os of 4 mg/kg of PQQ. The recovery of white blood cells, reticulocytes and bone marrow cells in the irradiation + PQQ group was faster than that in the irradiation group. Furthermore, the recovery of bone marrow cell in the irradiation + PQQ group was superior to that in irradiation + nilestriol group. Our results clearly indicate favourable effects on survival under higher lethal radiation doses and the ability of pyrroloquinoline quinine to enhance haemopoietic recovery after sublethal radiation exposure. PMID:22272111

  12. Role of glutathione in augmenting the anticancer activity of pyrroloquinoline quinone (PQQ).

    PubMed

    Shankar, Bhavani S; Pandey, Ruchi; Amin, Prayag; Misra, Hari S; Sainis, Krishna B

    2010-01-01

    Pyrroloquinoline quinone (PQQ), a bacterial redox co-factor and antioxidant, is highly reactive with nucleophilic compounds present in biological fluids. PQQ induced apoptosis in human promonocytic leukemia U937 cells and this was accompanied by depletion of the major cellular antioxidant glutathione and increase in intracellular reactive oxygen species (ROS). Treatment with glutathione (GSH) or N-acetyl-L-cysteine (NAC) did not spare PQQ toxicity but resulted in a 2-5-fold increase in PQQ-induced apoptosis in U937 cells. Cellular GSH levels increased following treatment by NAC alone but were severely depleted by co-treatment with NAC and PQQ. This was accompanied by an increase in intracellular ROS. Alternatively, depletion of glutathione also resulted in increased PQQ cytotoxicity. However, the cells underwent necrosis as evidenced by dual labeling with annexin V and propidium iodide. PQQ-induced cytotoxicity is thus critically regulated by the cellular redox status. An increase in GSH can augment apoptosis and its depletion can switch the mode of cell death to necrosis in the presence of PQQ. Our data suggest that modulation of intracellular GSH can be used as an effective strategy to potentiate cytotoxicity of quinones like PQQ.

  13. 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

  14. π-Electron manipulation of the 5,6-dihydroxyindole/quinone system by 3-alkynylation: mild acid-mediated entry to (cross)-conjugated scaffolds and paradigms for medium-tunable chromophores.

    PubMed

    Capelli, Luigia; Crescenzi, Orlando; Manini, Paola; Pezzella, Alessandro; Barone, Vincenzo; d'Ischia, Marco

    2011-06-03

    5,6-Dihydroxyindole-based systems engender increasing interest for the design and implementation of new functional aromatic scaffolds and eumelanin-like materials with tailored absorption and electronic properties. However, studies aimed at elucidating the influence of external π-conjugating groups on the redox properties and acid-induced reactivity of these highly oxidizable indolic platforms are lacking. We report herein the synthesis (as acetyl derivatives) and chemical/quantum chemical characterization of the first π-extended 5,6-dihydroxyindole derivatives, 3-ethynyl-5,6-dihydroxyindole (1) and 3,3'-(1,2-ethynediyl)bis-5,6-dihydroxyindole (2), in order to understand whether and how β extension of the enamine-like pyrrole sector affects the absorption properties, redox behavior, and protonation equilibria at both the o-diphenol and quinone levels. Oxidation of 1 and 2 proceeded smoothly to generate dark insoluble materials with eumelanin-like UV properties. On exposure to phosphate buffer at pH 3, 1 was rapidly converted to 3-acetyl-5,6-dihydroxyindole (5) and, in the presence of 5,6-dihydroxyindole, to the cross-conjugated 3,3'-ethenylidenebis-5,6-dihydroxyindole (6). DFT calculations on 1 and 2 and their quinones in their pristine states and after protonation provided a mechanistic frame to rationalize the unusual acid-mediated chemistry of 1 and disclosed 2-quinone as the prototype of a novel class of medium-dependent chromophores. The ethynyl(ene) structural motif is thus proposed as the key to new tunable π-electron extended 5,6-dihydroxyindole/5,6-indolequinone paradigms for the rational design of alkyne-containing hybrid eumelanin-type polymers.

  15. Crystal structures of Pseudomonas syringae pv. tomato DC3000 quinone oxidoreductase and its complex with NADPH

    SciTech Connect

    Pan, Xiaowei; Zhang, Hongmei; Gao, Yu; Li, Mei; Chang, Wenrui

    2009-12-18

    Zeta-crystallin-like quinone oxidoreductase is NAD(P)H-dependent and catalyzes one-electron reduction of certain quinones to generate semiquinone. Here we present the crystal structures of zeta-crystallin-like quinone oxidoreductase from Pseudomonas syringae pv. tomato DC3000 (PtoQOR) and its complexes with NADPH determined at 2.4 and 2.01 A resolutions, respectively. PtoQOR forms as a homologous dimer, each monomer containing two domains. In the structure of the PtoQOR-NADPH complex, NADPH locates in the groove between the two domains. NADPH binding causes obvious conformational changes in the structure of PtoQOR. The putative substrate-binding site of PtoQOR is wider than that of Escherichia coli and Thermus thermophilus HB8. Activity assays show that PtoQOR has weak 1,4-benzoquinone catalytic activity, and very strong reduction activity towards large substrates such as 9,10-phenanthrenequinone. We propose a model to explain the conformational changes which take place during reduction reactions catalyzed by PtoQOR.

  16. arNOX: generator of reactive oxygen species in the skin and sera of aging individuals subject to external modulation.

    PubMed

    Morré, Dorothy M; Meadows, Christiaan; Morré, D James

    2010-01-01

    An aging-related cell-surface oxidase (aging-related NADH oxidase, arNOX) generating superoxide and other reactive oxygen species is shed from the cell surface and is found in saliva, urine, perspiration, and interstitial fluids that surround the collagen and elastin matrix underlying dermis. arNOX activity correlates with age and reaches a maximum at about age 65 in males and 55 in females. arNOX activities are highly correlated with values of human skin where a causal relationship is indicated. Ongoing efforts focus on cloning arNOX proteins and development of antiaging formulas based on arNOX inhibition (intervention).

  17. Calcium and Mitochondrial Reactive Oxygen Species Generation: How to Read the Facts

    PubMed Central

    Adam-Vizi, Vera; Starkov, Anatoly A.

    2011-01-01

    A number of recent discoveries indicate that abnormal Ca2+ signaling, oxidative stress, and mitochondrial dysfunction are involved in the neuronal damage in Alzheimer’s disease. However, the literature on the interactions between these factors is controversial especially in the interpretation of the cause-effect relationship between mitochondrial damage induced by Ca2+ overload and the production of reactive oxygen species (ROS). In this review, we survey the experimental observations on the Ca2+-induced mitochondrial ROS production, explain the sources of controversy in interpreting these results, and discuss the different molecular mechanisms underlying the effect of Ca2+ on the ROS emission by brain mitochondria. PMID:20421693

  18. Calcium and mitochondrial reactive oxygen species generation: how to read the facts.

    PubMed

    Adam-Vizi, Vera; Starkov, Anatoly A

    2010-01-01

    A number of recent discoveries indicate that abnormal Ca2+ signaling, oxidative stress, and mitochondrial dysfunction are involved in the neuronal damage in Alzheimer's disease. However, the literature on the interactions between these factors is controversial especially in the interpretation of the cause-effect relationship between mitochondrial damage induced by Ca2+ overload and the production of reactive oxygen species (ROS). In this review, we survey the experimental observations on the Ca2+-induced mitochondrial ROS production, explain the sources of controversy in interpreting these results, and discuss the different molecular mechanisms underlying the effect of Ca2+ on the ROS emission by brain mitochondria.

  19. Response of mitochondrial reactive oxygen species generation to steady-state oxygen tension: implications for hypoxic cell signaling.

    PubMed

    Hoffman, David L; Salter, Jason D; Brookes, Paul S

    2007-01-01

    Mitochondria are proposed to play an important role in hypoxic cell signaling. One currently accepted signaling paradigm is that the mitochondrial generation of reactive oxygen species (ROS) increases in hypoxia. This is paradoxical, because oxygen is a substrate for ROS generation. Although the response of isolated mitochondrial ROS generation to [O(2)] has been examined previously, such investigations did not apply rigorous control over [O(2)] within the hypoxic signaling range. With the use of open-flow respirometry and fluorimetry, the current study determined the response of isolated rat liver mitochondrial ROS generation to defined steady-state [O(2)] as low as 0.1 microM. In mitochondria respiring under state 4 (quiescent) or state 3 (ATP turnover) conditions, decreased ROS generation was always observed at low [O(2)]. It is concluded that the biochemical mechanism to facilitate increased ROS generation in response to hypoxia in cells is not intrinsic to the mitochondrial respiratory chain alone but may involve other factors. The implications for hypoxic cell signaling are discussed.

  20. 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.

  1. 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.

  2. Ultrafast X-Ray Phase Contrast Imaging of a Gasless Reactive System Using 3RD Generation Synchrotron Radiation

    NASA Astrophysics Data System (ADS)

    Reeves, R. V.; White, J. D. E.; Dufresne, E. M.; Fezzaa, K.; Son, S. F.; Mukasyan, A. S.

    2009-12-01

    We report anultrafast x-ray phase-contrast imaging study of a gasless composite reactive (Si-coated W wire) system undergoing high heating rates (104-2.5×105 K/s). Construction of an imaging system utilizing a high-speed CMOS camera and the third-generation synchrotron at the Advanced Photon Source of Argonne National Laboratory allows for imaging of microstructural changes of the reactive system over previously unstudied time frames and length scales. Imaging was performed at speeds up to 36,000 frames per second with 10 μm spatial resolution. Using Computer-Assisted Electrothermography (CAE), the heating rate of the gasless reactive system W-Si is controlled and its kinetics is measured. A physical description of the changes undergone by the system during melting and reaction are captured by the high-speed imaging system and correlated to the recorded CAE data. The initial Si melt, as well as the initial reaction, is seen to be non-uniform along the wire. A secondary reaction, undetected by CAE data, is observed and tracked through the imaging.

  3. Xanthohumol induces generation of reactive oxygen species and triggers apoptosis through inhibition of mitochondrial electron transfer chain complex I.

    PubMed

    Zhang, Bo; Chu, Wei; Wei, Peng; Liu, Ying; Wei, Taotao

    2015-12-01

    Xanthohumol is a prenylflavonoid extracted from hops (Humulus lupulus). It possesses anti-cancer and anti-inflammatory activities in vitro and in vivo, and offers therapeutic benefits for treatment of metabolic syndromes. However, the precise mechanisms underlying its pharmacological effects remain to be elucidated, together with its cellular target. Here, we provide evidence that xanthohumol directly interacts with the mitochondrial electron transfer chain complex I (NADH dehydrogenase), inhibits the oxidative phosphorylation, triggers the production of reactive oxygen species, and induces apoptosis. In addition, we show that as a result of the inhibition of the mitochondrial oxidative phosphorylation, xanthohumol exposure causes a rapid decrease of mitochondrial transmembrane potential. Furthermore, we showed that xanthohumol up-regulates the glycolytic capacity in cells, and thus compensates cellular ATP generation. Dissection of the multiple steps of aerobic respiration by extracellular flux assays revealed that xanthohumol specifically inhibits the activity of mitochondrial complex I, but had little effect on that of complex II, III and IV. Inhibition of complex I by xanthohumol caused the overproduction of reactive oxygen species, which are responsible for the induction of apoptosis in cancer cells. We also found that isoxanthohumol, the structural isomer of xanthohumol, is inactive to cells, suggesting that the reactive 2-hydroxyl group of xanthohumol is crucial for its targeting to the mitochondrial complex I. Together, the remodeling of cell metabolism revealed here has therapeutic potential for the use of xanthohumol.

  4. New sterically-hindered o-quinones annelated with metal-dithiolates: regiospecificity in oxidative addition reactions of a bifacial ligand to the Pd and Pt complexes.

    PubMed

    Martyanov, K A; Cherkasov, V K; Abakumov, G A; Samsonov, M A; Khrizanforova, V V; Budnikova, Y H; Kuropatov, V A

    2016-04-25

    An unusual reactivity of sterically hindered o-quinones with an annelated dithiete ring towards coordination at a dithiolene site has been discovered. New Pd and Pt dithiolate complexes have been synthesized. The reaction proceeds regioselectively, and the quinone site of the parent ligand is not affected even while using an excess of the metal complex. Both Pt and Pd complexes display a square planar surrounding for the metal ion and have very similar NMR, IR and UV/Vis spectra. Surprisingly, being coordinated at the dithiolene site to the metal, the ligand exhibits activity like an o-quinone, it could be reduced with different metals resulting in the corresponding o-semiquinonates which were confirmed by EPR spectroscopy. It was shown that an unpaired electron exhibits HFC with the phosphorus nuclei of phosphine ligands coordinated to the metal ions at the dithiolene site of the molecule.

  5. A LAIR1 insertion generates broadly reactive antibodies against malaria variant antigens.

    PubMed

    Tan, Joshua; Pieper, Kathrin; Piccoli, Luca; Abdi, Abdirahman; Foglierini, Mathilde; Geiger, Roger; Tully, Claire Maria; Jarrossay, David; Ndungu, Francis Maina; Wambua, Juliana; Bejon, Philip; Fregni, Chiara Silacci; Fernandez-Rodriguez, Blanca; Barbieri, Sonia; Bianchi, Siro; Marsh, Kevin; Thathy, Vandana; Corti, Davide; Sallusto, Federica; Bull, Peter; Lanzavecchia, Antonio

    2016-01-07

    Plasmodium falciparum antigens expressed on the surface of infected erythrocytes are important targets of naturally acquired immunity against malaria, but their high number and variability provide the pathogen with a powerful means of escape from host antibodies. Although broadly reactive antibodies against these antigens could be useful as therapeutics and in vaccine design, their identification has proven elusive. Here we report the isolation of human monoclonal antibodies that recognize erythrocytes infected by different P. falciparum isolates and opsonize these cells by binding to members of the RIFIN family. These antibodies acquired broad reactivity through a novel mechanism of insertion of a large DNA fragment between the V and DJ segments. The insert, which is both necessary and sufficient for binding to RIFINs, encodes the entire 98 amino acid collagen-binding domain of LAIR1, an immunoglobulin superfamily inhibitory receptor encoded on chromosome 19. In each of the two donors studied, the antibodies are produced by a single expanded B-cell clone and carry distinct somatic mutations in the LAIR1 domain that abolish binding to collagen and increase binding to infected erythrocytes. These findings illustrate, with a biologically relevant example, a novel mechanism of antibody diversification by interchromosomal DNA transposition and demonstrate the existence of conserved epitopes that may be suitable candidates for the development of a malaria vaccine.

  6. A LAIR-1 insertion generates broadly reactive antibodies against malaria variant antigens

    PubMed Central

    Abdi, Abdirahman; Perez, Mathilde Foglierini; Geiger, Roger; Tully, Claire Maria; Jarrossay, David; Maina Ndungu, Francis; Wambua, Juliana; Bejon, Philip; Fregni, Chiara Silacci; Fernandez-Rodriguez, Blanca; Barbieri, Sonia; Bianchi, Siro; Marsh, Kevin; Thathy, Vandana; Corti, Davide; Sallusto, Federica

    2016-01-01

    Plasmodium falciparum antigens expressed on the surface of infected erythrocytes are important targets of naturally acquired immunity against malaria, but their high number and variability provide the pathogen with a powerful means of escape from host antibodies1–4. Although broadly reactive antibodies against these antigens could be useful as therapeutics and in vaccine design, their identification has proven elusive. Here, we report the isolation of human monoclonal antibodies that recognize erythrocytes infected by different P. falciparum isolates and opsonize these cells by binding to members of the RIFIN family. These antibodies acquired broad reactivity through a novel mechanism of insertion of a large DNA fragment between the V and DJ segments. The insert, which is both necessary and sufficient for binding to RIFINs, encodes the entire 100 amino acid collagen-binding domain of LAIR-1, an Ig superfamily inhibitory receptor encoded on chromosome 19. In each of the two donors studied, the antibodies are produced by a single expanded B cell clone and carry distinct somatic mutations in the LAIR-1 domain that abolish binding to collagen and increase binding to infected erythrocytes. These findings illustrate, with a biologically relevant example, a novel mechanism of antibody diversification by interchromosomal DNA transposition and demonstrate the existence of conserved epitopes that may be suitable candidates for the development of a malaria vaccine. PMID:26700814

  7. Next-generation re-sequencing of genes involved in increased platelet reactivity in diabetic patients on acetylsalicylic acid.

    PubMed

    Postula, Marek; Janicki, Piotr K; Eyileten, Ceren; Rosiak, Marek; Kaplon-Cieslicka, Agnieszka; Sugino, Shigekazu; Wilimski, Radosław; Kosior, Dariusz A; Opolski, Grzegorz; Filipiak, Krzysztof J; Mirowska-Guzel, Dagmara

    2016-06-01

    The objective of this study was to investigate whether rare missense genetic variants in several genes related to platelet functions and acetylsalicylic acid (ASA) response are associated with the platelet reactivity in patients with diabetes type 2 (T2D) on ASA therapy. Fifty eight exons and corresponding introns of eight selected genes, including PTGS1, PTGS2, TXBAS1, PTGIS, ADRA2A, ADRA2B, TXBA2R, and P2RY1 were re-sequenced in 230 DNA samples from T2D patients by using a pooled PCR amplification and next-generation sequencing by Illumina HiSeq2000. The observed non-synonymous variants were confirmed by individual genotyping of 384 DNA samples comprising of the individuals from the original discovery pools and additional verification cohort of 154 ASA-treated T2DM patients. The association between investigated phenotypes (ASA induced changes in platelets reactivity by PFA-100, VerifyNow and serum thromboxane B2 level [sTxB2]), and accumulation of rare missense variants (genetic burden) in investigated genes was tested using statistical collapsing tests. We identified a total of 35 exonic variants, including 3 common missense variants, 15 rare missense variants, and 17 synonymous variants in 8 investigated genes. The rare missense variants exhibited statistically significant difference in the accumulation pattern between a group of patients with increased and normal platelet reactivity based on PFA-100 assay. Our study suggests that genetic burden of the rare functional variants in eight genes may contribute to differences in the platelet reactivity measured with the PFA-100 assay in the T2DM patients treated with ASA.

  8. The Three-Dimensional Structure of NAD(P)H:Quinone Reductase, a Flavoprotein Involved in Cancer Chemoprotection and Chemotherapy: Mechanism of the Two-Electron Reduction

    NASA Astrophysics Data System (ADS)

    Li, Rongbao; Bianchet, Mario A.; Talalay, Paul; Amzel, L. Mario

    1995-09-01

    Quinone reductase [NAD(P)H:(quinone acceptor) oxidoreductase, EC 1.6.99.2], also called DT diaphorase, is a homodimeric FAD-containing enzyme that catalyzes obligatory NAD(P)H-dependent two-electron reductions of quinones and protects cells against the toxic and neoplastic effects of free radicals and reactive oxygen species arising from one-electron reductions. These two-electron reductions participate in the reductive bioactivation of cancer chemotherapeutic agents such as mitomycin C in tumor cells. Thus, surprisingly, the same enzymatic reaction that protects normal cells activates cytotoxic drugs used in cancer chemotherapy. The 2.1-Å crystal structure of rat liver quinone reductase reveals that the folding of a portion of each monomer is similar to that of flavodoxin, a bacterial FMN-containing protein. Two additional portions of the polypeptide chains are involved in dimerization and in formation of the two identical catalytic sites to which both monomers contribute. The crystallographic structures of two FAD-containing enzyme complexes (one containing NADP^+, the other containing duroquinone) suggest that direct hydride transfers from NAD(P)H to FAD and from FADH_2 to the quinone [which occupies the site vacated by NAD(P)H] provide a simple rationale for the obligatory two-electron reductions involving a ping-pong mechanism.

  9. Pyrroloquinoline quinone: Metabolism and analytical methods

    SciTech Connect

    Smidt, C.R.

    1990-01-01

    Pyrroloquinoline quinone (PQQ) functions as a cofactor for bacterial oxidoreductases. Whether or not PQQ serves as a cofactor in higher plants and animals remains controversial. Nevertheless, strong evidence exists that PQQ has nutritional importance. In highly purified, chemically defined diets PQQ stimulates animal growth. Further PQQ deprivation impairs connective tissue maturation, particularly when initiated in utero and throughout perinatal development. The study addresses two main objectives: (1) to elucidate basic aspects of the metabolism of PQQ in animals, and (2) to develop and improve existing analytical methods for PQQ. To study intestinal absorption of PQQ, ten mice were administered [[sup 14]C]-PQQ per os. PQQ was readily absorbed (62%) in the lower intestine and was excreted by the kidney within 24 hours. Significant amounts of labeled-PQQ were retained only by skin and kidney. Three approaches were taken to answer the question whether or not PQQ is synthesized by the intestinal microflora of mice. First, dietary antibiotics had no effect on fecal PQQ excretion. Then, no bacterial isolates could be identified that are known to synthesize PQQ. Last, cecal contents were incubated anaerobically with radiolabeled PQQ-precursors with no label appearing in isolated PQQ. Thus, intestinal PQQ synthesis is unlikely. Analysis of PQQ in biological samples is problematic since PQQ forms adducts with nucleophilic compounds and binds to the protein fraction. Existing analytical methods are reviewed and a new approach is introduced that allows for detection of PQQ in animal tissue and foods. PQQ is freed from proteins by ion exchange chromatography, purified on activated silica cartridges, detected by a colorimetric redox-cycling assay, and identified by mass spectrometry. That compounds with the properties of PQQ may be nutritionally important offers interesting areas for future investigation.

  10. Effect of electron-transport inhibitors on the generation of reactive oxygen species by pea mitochondria during succinate oxidation.

    PubMed

    Popov, V N; Ruuge, E K; Starkov, A A

    2003-07-01

    The effect of inhibitors of the cytochrome pathway and alternative oxidase on the rate of respiration and generation of reactive oxygen species by pea mitochondria was studied. Respiration of mitochondria from pea cotyledons was inhibited by 70-80% by salicylhydroxamate (SHAM). The rate of hydrogen peroxide production by pea cotyledon mitochondria during succinate oxidation was 0.15 nmol/min per mg protein. SHAM considerably accelerated the hydrogen peroxide production. The SHAM-dependent H2O2 production was stimulated by 2 micro M antimycin A and inhibited by 5 mM KCN and 1 micro M myxothiazol. The study of the rate of O2*- generation by pea mitochondria using EPR spin traps and epinephrine oxidation showed that H2O2 accumulation can be accounted for by a significant increase in the rate of O2*- production.

  11. Protein damage and reactive oxygen species generation induced by the synergistic effects of ultrasound and methylene blue

    NASA Astrophysics Data System (ADS)

    He, Ling-Ling; Wang, Xin; Wu, Xiao-Xia; Wang, Yong-Xia; Kong, Yu-Mei; Wang, Xin; Liu, Bing-Mi; Liu, Bin

    2015-01-01

    The sonodynamic damage to protein in the presence of methylene blue (MB) and the various influencing factors including ultrasonic irradiation time and MB concentration on the damage of protein were studied by fluorescence and absorption spectra. In addition, the mechanisms of the synergistic effects of ultrasound and MB were studied by oxidation-extraction photometry with several reactive oxygen species (ROS) scavengers. The results indicated that the damage of protein induced by the synergistic effects of ultrasound and MB were more serious than those that ultrasound or MB alone was applied. The damage of protein could be mainly due to the generation of ROS. The damage degree of protein increased with the increase of ultrasonic irradiation time and MB concentration because of the increased quantities of ROS generation. Both 1O2 and radOH were the important mediators of the ultrasound-inducing protein damage in the presence of MB.

  12. Caspase-independent cell death without generation of reactive oxygen species in irradiated MOLT-4 human leukemia cells.

    PubMed

    Yoshida, Kengo; Kubo, Yoshiko; Kusunoki, Yoichiro; Morishita, Yukari; Nagamura, Hiroko; Hayashi, Ikue; Kyoizumi, Seishi; Seyama, Toshio; Nakachi, Kei; Hayashi, Tomonori

    2009-01-01

    To improve our understanding of ionizing radiation effects on immune cells, we investigated steps leading to radiation-induced cell death in MOLT-4, a thymus-derived human leukemia cell. After exposure of MOLT-4 cells to 4 Gy of X-rays, irradiated cells sequentially showed increase in intracellular reactive oxygen species (ROS), decrease in mitochondrial membrane potential, and eventually apoptotic cell death. In the presence of the caspase inhibitor z-VAD-fmk, irradiated cells exhibited necrotic characteristics such as mitochondrial swelling instead of apoptosis. ROS generation was not detected during this necrotic cell death process. These results indicate that radiation-induced apoptosis in MOLT-4 cells requires elevation of intracellular ROS as well as activation of a series of caspases, whereas the cryptic necrosis program--which is independent of intracellular ROS generation and caspase activation--is activated when the apoptosis pathway is blocked.

  13. HVCN1 modulates BCR signal strength via regulation of BCR-dependent generation of reactive oxygen species

    PubMed Central

    Capasso, Melania; Bhamrah, Mandeep K; Henley, Tom; Boyd, Robert S; Langlais, Claudia; Cain, Kelvin; Dinsdale, David; Pulford, Karen; Kan, Mahmood; Musset, Boris; Cherny, Vladimir V; Morgan, Deri; Gascoyne, Randy D; Vigorito, Elena; DeCoursey, Thomas E; MacLennan, Ian C M; Dyer, Martin J S

    2011-01-01

    Voltage-gated proton currents regulate generation of reactive oxygen species (ROS) in phagocytic cells. In B cells, stimulation of the B cell antigen receptor (BCR) results in the production of ROS that participate in B cell activation, but the involvement of proton channels is unknown. We report here that the voltage-gated proton channel HVCN1 associated with the BCR complex and was internalized together with the BCR after activation. BCR-induced generation of ROS was lower in HVCN1-deficient B cells, which resulted in attenuated BCR signaling via impaired BCR-dependent oxidation of the tyrosine phosphatase SHP-1. This resulted in less activation of the kinases Syk and Akt, impaired mitochondrial respiration and glycolysis, and diminished antibody responses in vivo. Our findings identify unanticipated functions for proton channels in B cells and demonstrate the importance of ROS in BCR signaling and downstream metabolism. PMID:20139987

  14. In situ fluorescence spectroscopy correlates ionomer degradation to reactive oxygen species generation in an operating fuel cell.

    PubMed

    Prabhakaran, Venkateshkumar; Arges, Christopher G; Ramani, Vijay

    2013-11-21

    The rate of generation of reactive oxygen species (ROS) within the polymer electrolyte membrane (PEM) of an operating proton exchange member fuel cell (PEMFC) was monitored using in situ fluorescence spectroscopy. A modified barrier layer was introduced between the PEM and the electrocatalyst layer to eliminate metal-dye interactions and fluorescence resonance energy transfer (FRET) effects during measurements. Standard fuel cell operating parameters (temperature, relative humidity, and electrode potential) were systematically varied to evaluate their influence on the rate of ROS generation during PEMFC operation. Independently, the macroscopic rate of PEM degradation was measured by monitoring the fluoride ion emission rate (FER) in the effluent stream at each operating condition. The ROS generation reaction rate constant (estimated from the in situ fluorescence experiments) correlated perfectly with the measured FER across all conditions, demonstrating unequivocally for the first time that a direct correlation exists between in situ ROS generation and PEM macroscopic degradation. The activation energy for ROS generation within the PEM was estimated to be 12.5 kJ mol(-1).

  15. Influence of ionic liquid and ionic salt on protein against the reactive species generated using dielectric barrier discharge plasma

    NASA Astrophysics Data System (ADS)

    Attri, Pankaj; Sarinont, Thapanut; Kim, Minsup; Amano, Takaaki; Koga, Kazunori; Cho, Art E.; Ha Choi, Eun; Shiratani, Masaharu

    2015-12-01

    The presence of salts in biological solution can affect the activity of the reactive species (RS) generated by plasma, and so they can also have an influence on the plasma-induced sterilization. In this work, we assess the influence that diethylammonium dihydrogen phosphate (DEAP), an ionic liquid (IL), and sodium chloride (NaCl), an ionic salt (IS), have on the structural changes in hemoglobin (Hb) in the presence of RS generated using dielectric barrier discharge (DBD) plasma in the presence of various gases [O2, N2, Ar, He, NO (10%) + N2 and Air]. We carry out fluorescence spectroscopy to verify the generation of •OH with or without the presence of DEAP IL and IS, and we use electron spin resonance (ESR) to check the generation of H• and •OH. In addition, we verified the structural changes in the Hb structure after treatment with DBD in presence and absence of IL and IS. We then assessed the structural stability of the Hb in the presence of IL and IS by using molecular dynamic (MD) simulations. Our results indicate that the IL has a strong effect on the conservation of the Hb structure relative to that of IS against RS generated by plasma.

  16. Copper chelation by D-penicillamine generates reactive oxygen species that are cytotoxic to human leukemia and breast cancer cells.

    PubMed

    Gupte, Anshul; Mumper, Russell J

    2007-11-01

    Serum and tumor copper levels are significantly elevated in a variety of malignancies including breast, ovarian, gastric, lung, and leukemia. D-Penicillamine (D-pen), a copper-chelating agent, at low concentrations in the presence of copper generates concentration-dependent cytotoxic hydrogen peroxide (H(2)O(2)). The purpose of these studies was to investigate the in vitro cytotoxicity, intracellular reactive oxygen species (ROS) generation, and the reduction in intracellular thiol levels due to H(2)O(2) and other ROS generated from copper-catalyzed D-pen oxidation in human breast cancer cells (BT474, MCF-7) and human leukemia cells (HL-60, HL-60/VCR, HL-60/ADR). D-pen (< or = 400 microM) in the presence of cupric sulfate (10 microM) resulted in concentration-dependent cytotoxicity. Catalase was able to completely protect the cells, substantiating the involvement of H(2)O(2) in cancer cell cytotoxicity. A linear correlation between the D-pen concentration and the intracellular ROS generated was shown in both breast cancer and leukemia cells. D-pen in the presence of copper also resulted in a reduction in intracellular reduced thiol levels. The H(2)O(2)-mediated cytotoxicity was greater in leukemia cells compared to breast cancer cells. These results support the hypothesis that D-pen can be employed as a cytotoxic copper-chelating agent based on its ROS-generating ability.

  17. Influence of ionic liquid and ionic salt on protein against the reactive species generated using dielectric barrier discharge plasma

    PubMed Central

    Attri, Pankaj; Sarinont, Thapanut; Kim, Minsup; Amano, Takaaki; Koga, Kazunori; Cho, Art E.; Ha Choi, Eun; Shiratani, Masaharu

    2015-01-01

    The presence of salts in biological solution can affect the activity of the reactive species (RS) generated by plasma, and so they can also have an influence on the plasma-induced sterilization. In this work, we assess the influence that diethylammonium dihydrogen phosphate (DEAP), an ionic liquid (IL), and sodium chloride (NaCl), an ionic salt (IS), have on the structural changes in hemoglobin (Hb) in the presence of RS generated using dielectric barrier discharge (DBD) plasma in the presence of various gases [O2, N2, Ar, He, NO (10%) + N2 and Air]. We carry out fluorescence spectroscopy to verify the generation of •OH with or without the presence of DEAP IL and IS, and we use electron spin resonance (ESR) to check the generation of H• and •OH. In addition, we verified the structural changes in the Hb structure after treatment with DBD in presence and absence of IL and IS. We then assessed the structural stability of the Hb in the presence of IL and IS by using molecular dynamic (MD) simulations. Our results indicate that the IL has a strong effect on the conservation of the Hb structure relative to that of IS against RS generated by plasma. PMID:26656857

  18. Effect of plasma jet diameter on the efficiency of reactive oxygen and nitrogen species generation in water

    NASA Astrophysics Data System (ADS)

    Oh, Jun-Seok; Kakuta, Maito; Furuta, Hiroshi; Akatsuka, Hiroshi; Hatta, Akimitsu

    2016-06-01

    The plasma jet generation of reactive oxygen and nitrogen species (RONS) in solution is important in biology, medicine, and disinfection. Studies using a wide variety of plasma jet devices have been carried out for this purpose, making it difficult to compare the performance between devices. In this study, we compared the efficiency of RONS generation in deionized (DI) water between 3.7-mm- and 800-µm-sized helium (He) plasma jets (hereafter mm-jet and µm-jet, respectively) at different treatment distances and times. The efficiency of RONS generation was determined by considering the total amount of RONS generated in DI water with respect to the input energy and gas consumption. We found that the mm-jet generated 20% more RONS in the DI water than the µm-jet at the optimized distance. However, when the input power and He gas consumption were taken into account, we discovered that the µm-jet was 5 times more efficient in generating RONS in the DI water. Under the parameters investigated in this study, the concentration of RONS continued to increase as a function of treatment time (up to 30 min). However treatment distance had a marked effect on the efficiency of RONS generation: treatment distances of 25 and 30 mm were optimal for the mm-jet and µm-jet, respectively. Our method of comparing the efficiency of RONS generation in solution between plasma jets could be used as a reference protocol for the development of efficient plasma jet sources for use in medicine, biology, and agriculture.

  19. Optimization of degradation of Reactive Black 5 (RB5) and electricity generation in solar photocatalytic fuel cell system.

    PubMed

    Khalik, Wan Fadhilah; Ho, Li-Ngee; Ong, Soon-An; Voon, Chun-Hong; Wong, Yee-Shian; Yusoff, NikAthirah; Lee, Sin-Li; Yusuf, Sara Yasina

    2017-10-01

    The photocatalytic fuel cell (PFC) system was developed in order to study the effect of several operating parameters in degradation of Reactive Black 5 (RB5) and its electricity generation. Light irradiation, initial dye concentration, aeration, pH and cathode electrode are the operating parameters that might give contribution in the efficiency of PFC system. The degradation of RB5 depends on the presence of light irradiation and solar light gives better performance to degrade the azo dye. The azo dye with low initial concentration decolorizes faster compared to higher initial concentration and presence of aeration in PFC system would enhance its performance. Reactive Black 5 rapidly decreased at higher pH due to the higher amount of OH generated at higher pH and Pt-loaded carbon (Pt/C) was more suitable to be used as cathode in PFC system compared to Cu foil and Fe foil. The rapid decolorization of RB5 would increase their voltage output and in addition, it would also increase their Voc, Jsc and Pmax. The breakage of azo bond and aromatic rings was confirmed through UV-Vis spectrum and COD analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Oxidation of Levafix CA reactive azo-dyes in industrial wastewater of textile dyeing by electro-generated Fenton's reagent.

    PubMed

    El-Desoky, Hanaa S; Ghoneim, Mohamed M; El-Sheikh, Ragaa; Zidan, Naglaa M

    2010-03-15

    The indirect electrochemical removal of pollutants from effluents has become an attractive method in recent years. Removal (decolorization and mineralization) of Levafix Blue CA and Levafix Red CA reactive azo-dyes from aqueous media by electro-generated Fenton's reagent (Fe(2+)/H(2)O(2)) using a reticulated vitreous carbon cathode and a platinum gauze anode was optimized. Progress of oxidation (decolorization and mineralization) of the investigated azo-dyes with time of electro-Fenton's reaction was monitored by UV-visible absorbance measurements, Chemical oxygen demand (COD) removal and HPLC analysis. The results indicated that the electro-Fenton's oxidation system is efficient for treatment of such types of reactive dyes. Oxidation of each of the investigated azo-dyes by electro-generated Fenton's reagent up to complete decolorization and approximately 90-95% mineralization was achieved. Moreover, the optimized electro-Fenton's oxidation was successfully applied for complete decolorization and approximately 85-90% mineralization of both azo-dyes in real industrial wastewater samples collected from textile dyeing house at El-Mahalla El-Kobra, Egypt. (c) 2009 Elsevier B.V. All rights reserved.

  1. Regulatory mechanisms of nitric oxide and reactive oxygen species generation and their role in plant immunity.

    PubMed

    Yoshioka, Hirofumi; Mase, Keisuke; Yoshioka, Miki; Kobayashi, Michie; Asai, Shuta

    2011-08-01

    Rapid production of nitric oxide (NO) and reactive oxygen species (ROS) has been implicated in diverse physiological processes, such as programmed cell death, development, cell elongation and hormonal signaling, in plants. Much attention has been paid to the regulation of plant innate immunity by these signal molecules. Recent studies provide evidence that an NADPH oxidase, respiratory burst oxidase homolog, is responsible for pathogen-responsive ROS burst. However, we still do not know about NO-producing enzymes, except for nitrate reductase, although many studies suggest the existence of NO synthase-like activity responsible for NO burst in plants. Here, we introduce regulatory mechanisms of NO and ROS bursts by mitogen-activated protein kinase cascades, calcium-dependent protein kinase or riboflavin and its derivatives, flavin mononucleotide and flavin adenine dinucleotide, and we discuss the roles of the bursts in defense responses against plant pathogens.

  2. High osmotic pressure increases reactive oxygen species generation in rabbit corneal epithelial cells by endoplasmic reticulum

    PubMed Central

    Wang, Peng; Sheng, Minjie; Li, Bing; Jiang, Yaping; Chen, Yihui

    2016-01-01

    Tear high osmotic pressure (HOP) has been recognized as the core mechanism underlying ocular surface inflammation, injury and symptoms and is closely associated with many ocular surface diseases, especially dry eye. The endoplasmic reticulum (ER) is a multi-functional organelle responsible for protein synthesis, folding and transport, biological synthesis of lipids, vesicle transport and intracellular calcium storage. Accumulation of unfolded proteins and imbalance of calcium ion in the ER would induce ER stress and protective unfolded protein response (UPR). Many studies have demonstrated that ER stress can induce cell apoptosis. However, the association between tear HOP and ER stress has not been studied systematically. In the present study, rabbit corneal epithelial cells were treated with HOP and results showed that the production of reactive oxygen species increased markedly, which further activated the ER signaling pathway and ultimately induced cell apoptosis. These findings shed new lights on the pathogenesis and clinical treatment of dry eye and other ocular surface diseases. PMID:27158374

  3. Cadmium induces reactive oxygen species generation and lipid peroxidation in cortical neurons in culture.

    PubMed

    López, E; Arce, C; Oset-Gasque, M J; Cañadas, S; González, M P

    2006-03-15

    Cadmium is a toxic agent that it is also an environmental contaminant. Cadmium exposure may be implicated in some humans disorders related to hyperactivity and increased aggressiveness. This study presents data indicating that cadmium induces cellular death in cortical neurons in culture. This death could be mediated by an apoptotic and a necrotic mechanism. The apoptotic death may be mediated by oxidative stress with reactive oxygen species (ROS) formation which could be induced by mitochondrial membrane dysfunction since this cation produces: (a) depletion of mitochondrial membrane potential and (b) diminution of ATP levels with ATP release. Necrotic death could be mediated by lipid peroxidation induced by cadmium through an indirect mechanism (ROS formation). On the other hand, 40% of the cells survive cadmium action. This survival seems to be mediated by the ability of these cells to activate antioxidant defense systems, since cadmium reduced the intracellular glutathione levels and induced catalase and SOD activation in these cells.

  4. Fhit interaction with ferredoxin reductase triggers generation of reactive oxygen species and apoptosis of cancer cells.

    PubMed

    Trapasso, Francesco; Pichiorri, Flavia; Gaspari, Marco; Palumbo, Tiziana; Aqeilan, Rami I; Gaudio, Eugenio; Okumura, Hiroshi; Iuliano, Rodolfo; Di Leva, Giampiero; Fabbri, Muller; Birk, David E; Raso, Cinzia; Green-Church, Kari; Spagnoli, Luigi G; Venuta, Salvatore; Huebner, Kay; Croce, Carlo M

    2008-05-16

    Fhit protein is lost in most cancers, its restoration suppresses tumorigenicity, and virus-mediated FHIT gene therapy induces apoptosis and suppresses tumors in preclinical models. We have used protein cross-linking and proteomics methods to characterize a Fhit protein complex involved in triggering Fhit-mediated apoptosis. The complex includes Hsp60 and Hsp10 that mediate Fhit stability and may affect import into mitochondria, where it interacts with ferredoxin reductase, responsible for transferring electrons from NADPH to cytochrome P450 via ferredoxin. Viral-mediated Fhit restoration increases production of intracellular reactive oxygen species, followed by increased apoptosis of lung cancer cells under oxidative stress conditions; conversely, Fhit-negative cells escape apoptosis, carrying serious oxidative DNA damage that may contribute to an increased mutation rate. Characterization of Fhit interacting proteins has identified direct effectors of the Fhit-mediated apoptotic pathway that is lost in most cancers through loss of Fhit.

  5. Peroxisomes as cell generators of reactive nitrogen species (RNS) signal molecules.

    PubMed

    Corpas, Francisco J; Barroso, Juan B; Palma, José M; del Río, Luis A

    2013-01-01

    Nitric oxide is a gaseous free radical with a wide range of direct and indirect actions in plant cells. However, the enzymatic sources of NO and its subcellular localization in plants are still under debate. Among the different subcellular compartments where NO has been found to be produced, peroxisomes are the best characterized since in these organelles it has been demonstrated the presence of NO and it has been biochemically characterized a L-arginine-dependent nitric oxide synthase activity. This chapter summarizes the present knowledge of the NO metabolism and its derived reactive nitrogen species (RNS) in plant peroxisomes and how this gaseous free radical is involved in natural senescence, and is released to the cytosol under salinity stress conditions acting as a signal molecule.

  6. The HemQ coprohaem decarboxylase generates reactive oxygen species: implications for the evolution of classical haem biosynthesis.

    PubMed

    Hobbs, Charlie; Dailey, Harry A; Shepherd, Mark

    2016-11-01

    Bacteria require a haem biosynthetic pathway for the assembly of a variety of protein complexes, including cytochromes, peroxidases, globins, and catalase. Haem is synthesised via a series of tetrapyrrole intermediates, including non-metallated porphyrins, such as protoporphyrin IX, which is well known to generate reactive oxygen species in the presence of light and oxygen. Staphylococcus aureus has an ancient haem biosynthetic pathway that proceeds via the formation of coproporphyrin III, a less reactive porphyrin. Here, we demonstrate, for the first time, that HemY of S. aureus is able to generate both protoporphyrin IX and coproporphyrin III, and that the terminal enzyme of this pathway, HemQ, can stimulate the generation of protoporphyrin IX (but not coproporphyrin III). Assays with hydrogen peroxide, horseradish peroxidase, superoxide dismutase, and catalase confirm that this stimulatory effect is mediated by superoxide. Structural modelling reveals that HemQ enzymes do not possess the structural attributes that are common to peroxidases that form compound I [Fe(IV)==O](+), which taken together with the superoxide data leaves Fenton chemistry as a likely route for the superoxide-mediated stimulation of protoporphyrinogen IX oxidase activity of HemY. This generation of toxic free radicals could explain why HemQ enzymes have not been identified in organisms that synthesise haem via the classical protoporphyrin IX pathway. This work has implications for the divergent evolution of haem biosynthesis in ancestral microorganisms, and provides new structural and mechanistic insights into a recently discovered oxidative decarboxylase reaction. © 2016 The Author(s).

  7. Protein reactivity of 3,4-dihydroxyphenylacetaldehyde, a toxic dopamine metabolite, is dependent on both the aldehyde and the catechol.

    PubMed

    Rees, Jennifer N; Florang, Virginia R; Eckert, Laurie L; Doorn, Jonathan A

    2009-07-01

    Dopamine (DA) has been implicated as an endogenous neurotoxin to explain selective neurodegeneration, as observed for Parkinson's disease (PD). However, previous work demonstrated that 3,4-dihydroxyphenylacetaldehyde (DOPAL) was more toxic than DA. DOPAL is generated as a part of DA catabolism via the activity of monoamine oxidase, and the mechanism of DOPAL toxicity is proposed to involve protein modification. Previous studies have demonstrated protein reactivity via the aldehyde moiety; however, DOPAL contains two reactive functional groups (catechol and aldehyde), both with the potential for protein adduction. The goal of this work was to determine whether protein modification by DOPAL occurs via a thiol-reactive quinone generated from oxidation of the catechol, which is known to occur for DA, or if the aldehyde forms adducts with amine nucleophiles. To accomplish this objective, the reactivity of DOPAL toward N-acetyl-lysine (NAL), N-acetyl-cysteine (NAC), and two model proteins was determined. In addition, several DOPAL analogues were obtained and used for comparison of reactivity. Results demonstrate that at pH 7.4 and 37 degrees C, the order of DOPAL reactivity is NAL > NAC and the product of NAL and DOPAL is stable in the absence of reducing agent. Moreover, DOPAL will react with model proteins, but in the presence of amine-selective modifiers citraconic anhydride and 2-iminothiolane hydrochloride, the reactivity of DOPAL toward the proteins is diminished. In addition, DOPAL-mediated protein cross-linking is observed when a model protein or a protein mixture (i.e., mitochondria lysate) is treated with DOPAL at concentrations of 5-100 microM. Protein cross-linking was diminished in the presence of ascorbate, suggesting the involvement of a quinone in DOPAL-mediated protein modification. These data indicate that DOPAL is highly reactive toward protein nucleophiles with the potential for protein cross-linking.

  8. Mechanisms of rapid reactive oxygen species generation in response to cytosolic Ca2+ or Zn2+ loads in cortical neurons.

    PubMed

    Clausen, Aaron; McClanahan, Taylor; Ji, Sung G; Weiss, John H

    2013-01-01

    Excessive "excitotoxic" accumulation of Ca(2+) and Zn(2+) within neurons contributes to neurodegeneration in pathological conditions including ischemia. Putative early targets of these ions, both of which are linked to increased reactive oxygen species (ROS) generation, are mitochondria and the cytosolic enzyme, NADPH oxidase (NOX). The present study uses primary cortical neuronal cultures to examine respective contributions of mitochondria and NOX to ROS generation in response to Ca(2+) or Zn(2+) loading. Induction of rapid cytosolic accumulation of either Ca(2+) (via NMDA exposure) or Zn(2+) (via Zn(2+)/Pyrithione exposure in 0 Ca(2+)) caused sharp cytosolic rises in these ions, as well as a strong and rapid increase in ROS generation. Inhibition of NOX activation significantly reduced the Ca(2+)-induced ROS production with little effect on the Zn(2+)- triggered ROS generation. Conversely, dissipation of the mitochondrial electrochemical gradient increased the cytosolic Ca(2+) or Zn(2+) rises caused by these exposures, consistent with inhibition of mitochondrial uptake of these ions. However, such disruption of mitochondrial function markedly suppressed the Zn(2+)-triggered ROS, while partially attenuating the Ca(2+)-triggered ROS. Furthermore, block of the mitochondrial Ca(2+) uniporter (MCU), through which Zn(2+) as well as Ca(2+) can enter the mitochondrial matrix, substantially diminished Zn(2+) triggered ROS production, suggesting that the ROS generation occurs specifically in response to Zn(2+) entry into mitochondria. Finally, in the presence of the sulfhydryl-oxidizing agent 2,2'-dithiodipyridine, which impairs Zn(2+) binding to cytosolic metalloproteins, far lower Zn(2+) exposures were able to induce mitochondrial Zn(2+) uptake and consequent ROS generation. Thus, whereas rapid acute accumulation of Zn(2+) and Ca(2+) each can trigger injurious ROS generation, Zn(2+) entry into mitochondria via the MCU may do so with particular potency. This may be of

  9. RhoA and Rac1 GTPases Differentially Regulate Agonist-Receptor Mediated Reactive Oxygen Species Generation in Platelets.

    PubMed

    Akbar, Huzoor; Duan, Xin; Saleem, Saima; Davis, Ashley K; Zheng, Yi

    Agonist induced generation of reactive oxygen species (ROS) by NADPH oxidases (NOX) enhances platelet aggregation and hence the risk of thrombosis. RhoA and Rac1 GTPases are involved in ROS generation by NOX in a variety of cells, but their roles in platelet ROS production remain unclear. In this study we used platelets from RhoA and Rac1 conditional knockout mice as well as human platelets treated with Rhosin and NSC23767, rationally designed small molecule inhibitors of RhoA and Rac GTPases, respectively, to better define the contributions of RhoA and Rac1 signaling to ROS generation and platelet activation. Treatment of platelets with Rhosin inhibited: (a) U46619 induced activation of RhoA; (b) phosphorylation of p47phox, a critical component of NOX; (c) U46619 or thrombin induced ROS generation; (d) phosphorylation of myosin light chain (MLC); (e) platelet shape change; (f) platelet spreading on immobilized fibrinogen; and (g) release of P-selectin, secretion of ATP and aggregation. Conditional deletion of RhoA or Rac1 gene inhibited thrombin induced ROS generation in platelets. Addition of Y27632, a RhoA inhibitor, NSC23766 or Phox-I, an inhibitor of Rac1-p67phox interaction, to human platelets blocked thrombin induced ROS generation. These data suggest that: (a) RhoA/ROCK/p47phox signaling axis promotes ROS production that, at least in part, contributes to platelet activation in conjunction with or independent of the RhoA/ROCK mediated phosphorylation of MLC; and (b) RhoA and Rac1 differentially regulate ROS generation by inhibiting phosphorylation of p47phox and Rac1-p67phox interaction, respectively.

  10. RhoA and Rac1 GTPases Differentially Regulate Agonist-Receptor Mediated Reactive Oxygen Species Generation in Platelets

    PubMed Central

    Akbar, Huzoor; Duan, Xin; Saleem, Saima; Davis, Ashley K.; Zheng, Yi

    2016-01-01

    Agonist induced generation of reactive oxygen species (ROS) by NADPH oxidases (NOX) enhances platelet aggregation and hence the risk of thrombosis. RhoA and Rac1 GTPases are involved in ROS generation by NOX in a variety of cells, but their roles in platelet ROS production remain unclear. In this study we used platelets from RhoA and Rac1 conditional knockout mice as well as human platelets treated with Rhosin and NSC23767, rationally designed small molecule inhibitors of RhoA and Rac GTPases, respectively, to better define the contributions of RhoA and Rac1 signaling to ROS generation and platelet activation. Treatment of platelets with Rhosin inhibited: (a) U46619 induced activation of RhoA; (b) phosphorylation of p47phox, a critical component of NOX; (c) U46619 or thrombin induced ROS generation; (d) phosphorylation of myosin light chain (MLC); (e) platelet shape change; (f) platelet spreading on immobilized fibrinogen; and (g) release of P-selectin, secretion of ATP and aggregation. Conditional deletion of RhoA or Rac1 gene inhibited thrombin induced ROS generation in platelets. Addition of Y27632, a RhoA inhibitor, NSC23766 or Phox-I, an inhibitor of Rac1-p67phox interaction, to human platelets blocked thrombin induced ROS generation. These data suggest that: (a) RhoA/ROCK/p47phox signaling axis promotes ROS production that, at least in part, contributes to platelet activation in conjunction with or independent of the RhoA/ROCK mediated phosphorylation of MLC; and (b) RhoA and Rac1 differentially regulate ROS generation by inhibiting phosphorylation of p47phox and Rac1-p67phox interaction, respectively. PMID:27681226

  11. Variation in structure of proteins by adjusting reactive oxygen and nitrogen species generated from dielectric barrier discharge jet

    PubMed Central

    Park, Ji Hoon; Kim, Minsup; Shiratani, Masaharu; Cho, Art. E.; Choi, Eun Ha; Attri, Pankaj

    2016-01-01

    Over the last few years, the variation in liquid chemistry due to the development of radicals generated by cold atmospheric plasma (CAP) has played an important role in plasma medicine. CAP direct treatment or CAP activated media treatment in cancer cells shows promising anticancer activity for both in vivo and in vitro studies. However, the anticancer activity or antimicrobial activity varies between plasma devices due to the different abilities among plasma devices to generate the reactive oxygen and nitrogen species (RONS) at different ratios and in different concentrations. While the generation of RONS depends on many factors, the feeding gas plays the most important role among the factors. Hence, in this study we used different compositions of feeding gas while fixing all other plasma characteristics. We used Ar, Ar-O2 (at different ratios), and Ar-N2 (at different ratios) as the working gases for CAP and investigated the structural changes in proteins (Hemoglobin (Hb) and Myoglobin (Mb)). We then analyzed the influence of RONS generated in liquid on the conformations of proteins. Additionally, to determine the influence of H2O2 on the Hb and Mb structures, we used molecular dynamic simulation. PMID:27779212

  12. Variation in structure of proteins by adjusting reactive oxygen and nitrogen species generated from dielectric barrier discharge jet

    NASA Astrophysics Data System (ADS)

    Park, Ji Hoon; Kim, Minsup; Shiratani, Masaharu; Cho, Art. E.; Choi, Eun Ha; Attri, Pankaj

    2016-10-01

    Over the last few years, the variation in liquid chemistry due to the development of radicals generated by cold atmospheric plasma (CAP) has played an important role in plasma medicine. CAP direct treatment or CAP activated media treatment in cancer cells shows promising anticancer activity for both in vivo and in vitro studies. However, the anticancer activity or antimicrobial activity varies between plasma devices due to the different abilities among plasma devices to generate the reactive oxygen and nitrogen species (RONS) at different ratios and in different concentrations. While the generation of RONS depends on many factors, the feeding gas plays the most important role among the factors. Hence, in this study we used different compositions of feeding gas while fixing all other plasma characteristics. We used Ar, Ar-O2 (at different ratios), and Ar-N2 (at different ratios) as the working gases for CAP and investigated the structural changes in proteins (Hemoglobin (Hb) and Myoglobin (Mb)). We then analyzed the influence of RONS generated in liquid on the conformations of proteins. Additionally, to determine the influence of H2O2 on the Hb and Mb structures, we used molecular dynamic simulation.

  13. Sodium Lauryl Sulfate Stimulates the Generation of Reactive Oxygen Species through Interactions with Cell Membranes.

    PubMed

    Mizutani, Taeko; Mori, Ryota; Hirayama, Misaki; Sagawa, Yuki; Shimizu, Kenji; Okano, Yuri; Masaki, Hitoshi

    2016-12-01

    Sodium lauryl sulfate (SLS), a representative anionic surfactant, is well-known to induce rough skin following single or multiple topical applications. The mechanism by which SLS induces rough skin is thought to result from the disruption of skin moisture function consisting of NMF and epidermal lipids. However, a recent study demonstrated that topically applied SLS easily penetrates into the living cell layers of the epidermis, which suggests that physiological alterations of keratinocytes might cause the SLS-induced rough skin. This study was conducted to clarify the effects of SLS on keratinocytes to demonstrate the contribution of SLS to the induction of rough skin. In addition, the potentials of other widely used anionic surfactants to induce rough skin were evaluated. HaCaT keratinocytes treated with SLS had increased levels of intracellular ROS and IL-1α secretion. Application of SLS on the surface of a reconstructed epidermal equivalent also showed the increased generation of ROS. Further, SLS-treated cells showed an increase of intracellular calpain activity associated with the increase of intracellular Ca(2+) concentration. The increase of intracellular ROS was abolished by the addition of BAPTA-AM, a specific chelator of Ca(2+). In addition, IL-1α also stimulated ROS generation by HaCaT keratinocytes. An ESR spin-labeling study demonstrated that SLS increased the fluidity of membranes of liposomes and cells. Together, those results indicate that SLS initially interacts with cell membranes, which results in the elevation of intracellular Ca(2+) influx. Ca(2+) stimulates the secretion of IL-1α due to the activation of calpain, and also increases ROS generation. IL-1α also stimulates ROS generation by HaCaT keratinocytes. We conclude from these results that the elevation of intracellular ROS levels is one of the causes of SLS-induced rough skin. Finally, among the other anionic surfactants tested, sodium lauryl phosphate has less potential to induce

  14. Generation of reactive oxygen species (ROS) is a key factor for stimulation of macrophage proliferation by ceramide 1-phosphate

    SciTech Connect

    Arana, Lide; Gangoiti, Patricia; Ouro, Alberto; Rivera, Io-Guane; Ordonez, Marta; Trueba, Miguel; Lankalapalli, Ravi S.; Bittman, Robert; Gomez-Munoz, Antonio

    2012-02-15

    We previously demonstrated that ceramide 1-phosphate (C1P) is mitogenic for fibroblasts and macrophages. However, the mechanisms involved in this action were only partially described. Here, we demonstrate that C1P stimulates reactive oxygen species (ROS) formation in primary bone marrow-derived macrophages, and that ROS are required for the mitogenic effect of C1P. ROS production was dependent upon prior activation of NADPH oxidase by C1P, which was determined by measuring phosphorylation of the p40phox subunit and translocation of p47phox from the cytosol to the plasma membrane. In addition, C1P activated cytosolic calcium-dependent phospholipase A{sub 2} and protein kinase C-{alpha}, and NADPH oxidase activation was blocked by selective inhibitors of these enzymes. These inhibitors, and inhibitors of ROS production, blocked the mitogenic effect of C1P. By using BHNB-C1P (a photolabile caged-C1P analog), we demonstrate that all of these C1P actions are caused by intracellular C1P. It can be concluded that the enzyme responsible for C1P-stimulated ROS generation in bone marrow-derived macrophages is NADPH oxidase, and that this enzyme is downstream of PKC-{alpha} and cPLA{sub 2}-{alpha} in this pathway. -- Highlights: Black-Right-Pointing-Pointer Ceramide 1-phosphate (C1P) stimulates reactive oxygen species (ROS) formation. Black-Right-Pointing-Pointer The enzyme responsible for ROS generation by C1P in macrophages is NADPH oxidase. Black-Right-Pointing-Pointer NADPH oxidase lies downstream of cPLA{sub 2}-{alpha} and PKC-{alpha} in this pathway. Black-Right-Pointing-Pointer ROS generation is essential for the stimulation of macrophage proliferation by C1P.

  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. Colloidal gold nanorings for improved photodynamic therapy through field-enhanced generation of reactive oxygen species

    NASA Astrophysics Data System (ADS)

    Hu, Yue; Yang, Yamin; Wang, Hongjun; Du, Henry

    2013-02-01

    Au nanostructures that exhibit strong localized surface plasmon resonance (SPR) have excellent potential for photo-medicine, among a host of other applications. Here, we report the synthesis and use of colloidal gold nanorings (GNRs) with potential for enhanced photodynamic therapy of cancer. The GNRs were fabricated via galvanic replacement reaction of sacrificial Co nanoparticles in gold salt solution with low molecular weight (Mw = 2,500) poly(vinylpyrrolidone) (PVP) as a stabilizing agent. The size and the opening of the GNRs were controlled by the size of the starting Co particles and the concentration of the gold salt. UV-Vis absorption measurements indicated the tunability of the SPR of the GNRs from 560 nm to 780 nm. MTT assay showed that GNRs were non-toxic and biocompatible when incubated with breast cancer cells as well as the healthy counterpart cells. GNRs conjugated with 5-aminolevulinic acid (5-ALA) photosensitizer precursor led to elevated formation of reactive oxygen species and improved efficacy of photodynamic therapy of breast cancer cells under light irradiation compared to 5-ALA alone. These results can be attributed to significantly enhance localized electromagnetic field of the GNRs.

  17. Ligation of Glycophorin A Generates Reactive Oxygen Species Leading to Decreased Red Blood Cell Function.

    PubMed

    Khoory, Joseph; Estanislau, Jessica; Elkhal, Abdallah; Lazaar, Asmae; Melhorn, Mark I; Brodsky, Abigail; Illigens, Ben; Hamachi, Itaru; Kurishita, Yasutaka; Ivanov, Alexander R; Shevkoplyas, Sergey; Shapiro, Nathan I; Ghiran, Ionita C

    2016-01-01

    Acute, inflammatory conditions associated with dysregulated complement activation are characterized by significant increases in blood concentration of reactive oxygen species (ROS) and ATP. The mechanisms by which these molecules arise are not fully understood. In this study, using luminometric- and fluorescence-based methods, we show that ligation of glycophorin A (GPA) on human red blood cells (RBCs) results in a 2.1-fold, NADPH-oxidase-dependent increase in intracellular ROS that, in turn, trigger multiple downstream cascades leading to caspase-3 activation, ATP release, and increased band 3 phosphorylation. Functionally, using 2D microchannels to assess membrane deformability, GPS-ligated RBCs travel 33% slower than control RBCs, and lipid mobility was hindered by 10% using fluorescence recovery after photobleaching (FRAP). These outcomes were preventable by pretreating RBCs with cell-permeable ROS scavenger glutathione monoethyl ester (GSH-ME). Our results obtained in vitro using anti-GPA antibodies were validated using complement-altered RBCs isolated from control and septic patients. Our results suggest that during inflammatory conditions, circulating RBCs significantly contribute to capillary flow dysfunctions, and constitute an important but overlooked source of intravascular ROS and ATP, both critical mediators responsible for endothelial cell activation, microcirculation impairment, platelet activation, as well as long-term dysregulated adaptive and innate immune responses.

  18. Ligation of Glycophorin A Generates Reactive Oxygen Species Leading to Decreased Red Blood Cell Function

    PubMed Central

    Khoory, Joseph; Estanislau, Jessica; Elkhal, Abdallah; Lazaar, Asmae; Melhorn, Mark I.; Brodsky, Abigail; Illigens, Ben; Hamachi, Itaru; Kurishita, Yasutaka; Ivanov, Alexander R.; Shevkoplyas, Sergey; Shapiro, Nathan I.; Ghiran, Ionita C.

    2016-01-01

    Acute, inflammatory conditions associated with dysregulated complement activation are characterized by significant increases in blood concentration of reactive oxygen species (ROS) and ATP. The mechanisms by which these molecules arise are not fully understood. In this study, using luminometric- and fluorescence-based methods, we show that ligation of glycophorin A (GPA) on human red blood cells (RBCs) results in a 2.1-fold, NADPH-oxidase-dependent increase in intracellular ROS that, in turn, trigger multiple downstream cascades leading to caspase-3 activation, ATP release, and increased band 3 phosphorylation. Functionally, using 2D microchannels to assess membrane deformability, GPS-ligated RBCs travel 33% slower than control RBCs, and lipid mobility was hindered by 10% using fluorescence recovery after photobleaching (FRAP). These outcomes were preventable by pretreating RBCs with cell-permeable ROS scavenger glutathione monoethyl ester (GSH-ME). Our results obtained in vitro using anti-GPA antibodies were validated using complement-altered RBCs isolated from control and septic patients. Our results suggest that during inflammatory conditions, circulating RBCs significantly contribute to capillary flow dysfunctions, and constitute an important but overlooked source of intravascular ROS and ATP, both critical mediators responsible for endothelial cell activation, microcirculation impairment, platelet activation, as well as long-term dysregulated adaptive and innate immune responses. PMID:26784696

  19. Reactive-power compensation of coal mining excavators by using a new-generation STATCOM

    SciTech Connect

    Bilgin, H.F.; Ermis, M.; Kose, K.N.; Cadirci, I.; Acik, A.; Demirci, T.; Terciyanli, A.; Kocak, C.; Yorukoglu, M.

    2007-01-15

    This paper deals with the development and implementation of a current-source-converter-based static synchronous compensator (CSC-STATCOM) applied to the volt-ampere-reactive (VAR) compensation problem of coal mining excavators. It is composed of a +/- 750-kVAR full-bridge CSC with selective harmonic elimination, a low-pass input filter tuned to 200 Hz, and a Delta/Y-connected coupling transformer for connection to medium-voltage load bus. Each power semiconductor switch is composed of an asymmetrical integrated gate commutated thyristor (IGCT) connected in series with a reverse-blocking diode and switched at 500 Hz to eliminate 5th, 7th, 11th, and 13th current harmonics produced by the CSC. Operating principles, power stage, design of dc link, and input filter are also described in this paper. It has been verified by field tests that the developed STATCOM follows rapid fluctuations in nearly symmetrical lagging and leading VAR consumption of electric excavators, resulting in nearly unity power factor on monthly basis, and the harmonic current spectra in the lines of CSC-STATCOM at the point of common coupling comply with the IEEE Standard 519-1992.

  20. Diabetes-Induced Reactive Oxygen Species: Mechanism of Their Generation and Role in Renal Injury

    PubMed Central

    Fakhruddin, Selim; Alanazi, Wael

    2017-01-01

    Diabetes induces the onset and progression of renal injury through causing hemodynamic dysregulation along with abnormal morphological and functional nephron changes. The most important event that precedes renal injury is an increase in permeability of plasma proteins such as albumin through a damaged glomerular filtration barrier resulting in excessive urinary albumin excretion (UAE). Moreover, once enhanced UAE begins, it may advance renal injury from progression of abnormal renal hemodynamics, increased glomerular basement membrane (GBM) thickness, mesangial expansion, extracellular matrix accumulation, and glomerulosclerosis to eventual end-stage renal damage. Interestingly, all these pathological changes are predominantly driven by diabetes-induced reactive oxygen species (ROS) and abnormal downstream signaling molecules. In diabetic kidney, NADPH oxidase (enzymatic) and mitochondrial electron transport chain (nonenzymatic) are the prominent sources of ROS, which are believed to cause the onset of albuminuria followed by progression to renal damage through podocyte depletion. Chronic hyperglycemia and consequent ROS production can trigger abnormal signaling pathways involving diverse signaling mediators such as transcription factors, inflammatory cytokines, chemokines, and vasoactive substances. Persistently, increased expression and activation of these signaling molecules contribute to the irreversible functional and structural changes in the kidney resulting in critically decreased glomerular filtration rate leading to eventual renal failure. PMID:28164134

  1. Trial of Growth Control of Farm-raised Fish by Plasma-generated Reactive Species

    NASA Astrophysics Data System (ADS)

    Motomura, Hideki; Kubota, Yoshiki; Fukushima, Ryo; Ikeda, Yoshihisa; Jinno, Masafumi

    2016-09-01

    As one of the biological applications of plasmas, growth control of agricultural products attracts attentions. There are many papers on growth enhancement of crops by plasma treatment. However, there are few published papers concerning growth enhancement of fishery products excepting reports of goldfish growth enhancement in 1980s. In this study, growth characteristics of edible fish (tilapia) under the plasma treatment has been investigated. An arc discharge reactor was employed and plasma treated air was introduced to two aquariums with a flow rate of 2.5 L/min. Measured concentrations of main reactive species were 43 ppm for NO, 23 ppm for NO2 and 7.5 ppm for O3. Each aquarium had 60 L capacity and contained 15 tilapia fish. The plasma treated air was supplied to an aquarium once a day and to the other aquarium twice a day with total duration of 10 min. Compared to no plasma treatment case, the growth rate decreased by 18% by once a day plasma treatment, whereas almost same growth rate was observed by twice a day plasma treatment. A possible reason of growth suppression is excess concentrations of nitrite and nitrate in water. The relationship between their concentrations and growth characteristics under several treatment conditions will be shown at the conference. Tirapia fish was supplied from SEFREC of Ehime University.

  2. Lysosomal membrane permeabilization: Carbon nanohorn-induced reactive oxygen species generation and toxicity by this neglected mechanism

    SciTech Connect

    Yang, Mei; Zhang, Minfang; Tahara, Yoshio; Chechetka, Svetlana; Miyako, Eijiro; Iijima, Sumio; Yudasaka, Masako

    2014-10-01

    Understanding the molecular mechanisms responsible for the cytotoxic effects of carbon nanomaterials is important for their future biomedical applications. Carbon nanotubular materials induce the generation of reactive oxygen species (ROS), which causes cell death; however, the exact details of this process are still unclear. Here, we identify a mechanism of ROS generation that is involved in the apoptosis of RAW264.7 macrophages caused by excess uptake of carbon nanohorns (CNHs), a typical type of carbon nanotubule. CNH accumulated in the lysosomes, where they induced lysosomal membrane permeabilization (LMP) and the subsequent release of lysosomal proteases, such as cathepsins, which in turn caused mitochondrial dysfunction and triggered the generation of ROS in the mitochondria. The nicotinamide adenine dinucleotide phosphate oxidase was not directly involved in CNH-related ROS production, and the ROS generation cannot be regulated by mitochondrial electron transport chain. ROS fed back to amplify the mitochondrial dysfunction, leading to the subsequent activation of caspases and cell apoptosis. Carbon nanotubules commonly accumulate in the lysosomes after internalization in cells; however, lysosomal dysfunction has not attracted much attention in toxicity studies of these materials. These results suggest that LMP, a neglected mechanism, may be the primary reason for carbon nanotubule toxicity. - Highlights: • We clarify an apoptotic mechanism of RAW264.7 cells caused by carbon nanohorns. • In the meantime, the mechanism of CNH-induced ROS generation is identified. • LMP is the initial factor of CNH-induced ROS generation and cell death. • Cathepsins work as mediators that connect LMP and mitochondrial dysfunction.

  3. Development and characterization of a panel of cross-reactive monoclonal antibodies generated using H1N1 influenza virus.

    PubMed

    Guo, Chun-yan; Tang, Yi-gui; Qi, Zong-li; Liu, Yang; Zhao, Xiang-rong; Huo, Xue-ping; Li, Yan; Feng, Qing; Zhao, Peng-hua; Wang, Xin; Li, Yuan; Wang, Hai-fang; Hu, Jun; Zhang, Xin-jian

    2015-08-01

    To characterize the antigenic epitopes of the hemagglutinin (HA) protein of H1N1 influenza virus, a panel consisting of 84 clones of murine monoclonal antibodies (mAbs) were generated using the HA proteins from the 2009 pandemic H1N1 vaccine lysate and the seasonal influenza H1N1(A1) vaccines. Thirty-three (39%) of the 84 mAbs were found to be strain-specific, and 6 (7%) of the 84 mAbs were subtype-specific. Twenty (24%) of the 84 mAbs recognized the common HA epitopes shared by 2009 pandemic H1N1, seasonal A1 (H1N1), and A3 (H3N2) influenza viruses. Twenty-five of the 84 clones recognized the common HA epitopes shared by the 2009 pandemic H1N1, seasonal A1 (H1N1) and A3 (H3N2) human influenza viruses, and H5N1 and H9N2 avian influenza viruses. We found that of the 16 (19%) clones of the 84 mAbs panel that were cross-reactive with human respiratory pathogens, 15 were made using the HA of the seasonal A1 (H1N1) virus and 1 was made using the HA of the 2009 pandemic H1N1 influenza virus. Immunohistochemical analysis of the tissue microarray (TMA) showed that 4 of the 84 mAb clones cross-reacted with human tissue (brain and pancreas). Our results indicated that the influenza virus HA antigenic epitopes not only induce type-, subtype-, and strain-specific monoclonal antibodies against influenza A virus but also cross-reactive monoclonal antibodies against human tissues. Further investigations of these cross-reactive (heterophilic) epitopes may significantly improve our understanding of viral antigenic variation, epidemics, pathophysiologic mechanisms, and adverse effects of influenza vaccines.

  4. Analysis of reactive oxygen species generating systems in rat epididymal spermatozoa.

    PubMed

    Vernet, P; Fulton, N; Wallace, C; Aitken, R J

    2001-10-01

    Epididymal sperm maturation culminates in the acquisition of functional competence by testicular spermatozoa. The expression of this functional state is dependent upon a redox-regulated, cAMP-mediated signal transduction cascade that controls the tyrosine phosphorylation status of the spermatozoa during capacitation. Analysis of superoxide anion (O2(-.)) generation by rat epididymal spermatozoa has revealed a two-component process involving electron leakage from the sperm mitochondria at complexes I and II and a plasma membrane NAD(P)H oxidoreductase. Following incubation in a glucose-, lactate-, and pyruvate-free medium (-GLP), O2(-.) generation was suppressed by 86% and 96% in caput and cauda spermatozoa, respectively. The addition of lactate, malate, or succinate to spermatozoa incubated in medium -GLP stimulated O2(-.) generation. This increase could be blocked by rotenone and oligomycin (R/O) in the presence of malate or lactate but not succinate. Stimulation with all three substrates, as well as spontaneous O2(-.) production in +GLP medium, was blocked by the flavoprotein inhibitor, diphenylene iodonium. Diphenylene iodonium, but not R/O, suppressed NAD(P)H-induced lucigenin-dependent chemiluminescence. This NAD(P)H-dependent enzyme resided in the sperm plasma membrane and its activity was regulated by zinc and uncharacterized cytosolic factors. Reverse transcription-polymerase chain reaction analysis indicated that the sperm NAD(P)H oxidoreductase complex is quite distinct from the equivalent leukocyte system.

  5. Friedel Craft's synthesis and characterization of some acene quinone compounds

    SciTech Connect

    Galleguillos, R.; Litt, M.; Rickert, S.E.

    1987-01-01

    The synthesis and characterization of some linear acene quinones of up to nine fused rings prepared by the Friedel-Craft's reaction of hydroquinone (HQ) and 1,4,9,10 tetrahydroxy anthracene (THA) with pyromellitic dianhydride (PMDA), and fused AlCl/sub 3/, was carried out. The intermediate product of the reaction of THA and PMDA, 1,4 dihydroxy anthraquinone, 6,7 dicarboxylic acid (DADCA) was also isolated and its synthesis optimized. This material was reduced to 1,4,9,10-tetrahydroxy anthracene 6,7-dicarboxylic acid (TADCA) and further dehydrated to its anhydride (TADCAmh). These compounds contain the necessary chemical functionalities which may lead to the facile synthesis of higher molecular weight quinones. These acene quinones show electronic spectral absorptions extending far into the NIR region, an indication of their long conjunction length.

  6. Electronic transport properties of a quinone-based molecular switch

    NASA Astrophysics Data System (ADS)

    Zheng, Ya-Peng; Bian, Bao-An; Yuan, Pei-Pei

    2016-09-01

    In this paper, we carried out first-principles calculations based on density functional theory and non-equilibrium Green's function to investigate the electronic transport properties of a quinone-based molecule sandwiched between two Au electrodes. The molecular switch can be reversibly switched between the reduced hydroquinone (HQ) and oxidized quinone (Q) states via redox reactions. The switching behavior of two forms is analyzed through their I- V curves, transmission spectra and molecular projected self-consistent Hamiltonian at zero bias. Then we discuss the transmission spectra of the HQ and Q forms at different bias, and explain the oscillation of current according to the transmission eigenstates of LUMO energy level for Q form. The results suggest that this kind of a quinone-based molecule is usable as one of the good candidates for redox-controlled molecular switches.

  7. Quinones as Strecker degradation reagents in wine oxidation processes.

    PubMed

    Oliveira, Carla Maria; Santos, Sónia A O; Silvestre, Armando J D; Barros, António S; Ferreira, António César Silva; Silva, Artur M S

    2017-08-01

    The Strecker aldehydes formed during the reaction between α-amino acids (phenylalanine or methionine) and either gallic acid, caffeic acid or (+)-catechin ortho-quinones were evaluated in wine-model systems. It was demonstrated that phenylacetaldehyde was formed by quinone intermediates at wine pH. The highest amounts of phenylacetaldehyde during the 10days of experiment (69±5µg/L/day; 7x>Control) were obtained from (+) catechin, followed by gallic acid (61±4µg/L/day; 6x>Control) and caffeic acid (41±4µg/L/day; 4x>Control). The intermediate structures delivered from the reaction of ortho-quinones with α-amino acids were demonstrated by MS(n). Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Photochemical generation of reactive species upon irradiation of rainwater: negligible photoactivity of dissolved organic matter.

    PubMed

    Albinet, Alexandre; Minero, Claudio; Vione, Davide

    2010-07-15

    This paper focuses on the study of the photochemical activity of dissolved organic matter present in rainwater. Formation rates of the reactive species hydroxyl radical (OH(*)), singlet oxygen ((1)O(2)) and dissolved organic matter triplet states ((3)DOM()) were determined by irradiation (UV-A) of wet-only rainwater samples collected in Turin (Italy) in the presence of specific scavengers (benzene, furfuryl alcohol and phenol, respectively). Photo-formation rates of OH(*) ( approximately 3.10(-)(11)Ms(-)(1)) and (1)O(2) ( approximately 10(-)(14)Ms(-)(1)) were lower (1 or 2 orders of magnitude) or largely lower (4 to 10 orders of magnitude) than those determined for fog and cloud samples in previous studies. (3)DOM() formation rate values were either negligible or quite low ( approximately 10(-)(12)Ms(-)(1)) by comparison with those evaluated for surface water samples. Deduced steady-state [OH(*)] were in the same range as those reported for fog samples in the literature (8.7.10(-)(16) to 1.5.10(-)(15)M), while [(1)O(2)] was often several orders of magnitude lower and, therefore, could be considered as negligible. Nitrite (NO(2)(-)) constituted the main source of OH(*) (69 + or - 21 to 138 + or - 36%), and the deduced contribution of DOM was low or nil. All the results obtained in this study tend to demonstrate that DOM (including HUmic LIke Substances, HULIS) present in rainwater is poorly or not photoactive. Therefore, there could be considerable difference between rainwater DOM (HULIS included) and the organic matter present in surface waters, particularly the humic substances, as far as the photochemical activity is concerned. Copyright 2010 Elsevier B.V. All rights reserved.

  9. Costunolide induces apoptosis in platinum-resistant human ovarian cancer cells by generating reactive oxygen species.

    PubMed

    Yang, Yeong-In; Kim, Ji-Hyun; Lee, Kyung-Tae; Choi, Jung-Hye

    2011-12-01

    The acquired resistance to platinum-based drugs has become an obstacle in the management of ovarian cancer. We investigated the apoptosis-inducing effect of costunolide, a natural sesquiterpene lactone, in platinum-resistant human ovarian cancer cells, along with the molecular mechanism of action. Costunolide and cisplatin were examined in platinum-resistant human ovarian cancer cells. MTT assay for cell viability, PI staining for cell cycle profiling, and Annexin V assay for apoptosis analysis. ROS production and protein expression was assessed by H(2)DCFDA staining and Western blotting, respectively. Combination effect was determined using the Combination Index (CI) method. It was found that costunolide is more potent than cisplatin in inhibiting cell growth in three platinum-resistant ovarian cancer cell lines (MPSC1(PT), A2780(PT), and SKOV3(PT)). Costunolide induced apoptosis of platinum-resistant cells in a time- and dose-dependent manner and suppressed tumor growth in SKOV3(PT)-bearing mouse model. In addition, costunolide triggered the activation of caspase-3, -8, and -9. Pretreatment with caspase inhibitors neutralized the pro-apoptotic activity of costunolide. We further demonstrated that costunolide induced a significant increase in intracellular reactive oxygen species (ROS). Additionally, the antioxidant N-acetyl-L-cysteine (NAC) significantly attenuated the costunolide-induced production of ROS, activation of caspases, down-regulation of Bcl-2, and apoptosis in platinum-resistant ovarian cancer cells. Moreover, costunolide synergized with cisplatin to induce cell death in platinum-resistant ovarian cancer cells. Taken together, these data suggest that costunolide, alone or in combination with cisplatin, may be of therapeutic potential in platinum-resistant ovarian cancer. Copyright © 2011. Published by Elsevier Inc.

  10. Hierarchical Testing with Automated Document Generation for Amanzi, ASCEM's Subsurface Flow and Reactive Transport Simulator

    NASA Astrophysics Data System (ADS)

    Moulton, J. D.; Steefel, C. I.; Yabusaki, S.; Castleton, K.; Scheibe, T. D.; Keating, E. H.; Freedman, V. L.

    2013-12-01

    The Advanced Simulation Capabililty for Environmental Management (ASCEM) program is developing an approach and open-source tool suite for standardized risk and performance assessments at legacy nuclear waste sites. These assessments use a graded and iterative approach, beginning with simplified highly abstracted models, and adding geometric and geologic complexity as understanding is gained. To build confidence in this assessment capability, extensive testing of the underlying tools is needed. Since the tools themselves, such as the subsurface flow and reactive-transport simulator, Amanzi, are under active development, testing must be both hierarchical and highly automated. In this presentation we show how we have met these requirements, by leveraging the python-based open-source documentation system called Sphinx with several other open-source tools. Sphinx builds on the reStructured text tool docutils, with important extensions that include high-quality formatting of equations, and integrated plotting through matplotlib. This allows the documentation, as well as the input files for tests, benchmark and tutorial problems, to be maintained with the source code under a version control system. In addition, it enables developers to build documentation in several different formats (e.g., html and pdf) from a single source. We will highlight these features, and discuss important benefits of this approach for Amanzi. In addition, we'll show that some of ASCEM's other tools, such as the sampling provided by the Uncertainty Quantification toolset, are naturally leveraged to enable more comprehensive testing. Finally, we will highlight the integration of this hiearchical testing and documentation framework with our build system and tools (CMake, CTest, and CDash).

  11. Smoke Extract Impairs Adenosine Wound Healing. Implications of Smoke-Generated Reactive Oxygen Species

    PubMed Central

    Zimmerman, Matthew C.; Zhang, Hui; Castellanos, Glenda; O’Malley, Jennifer K.; Alvarez-Ramirez, Horacio; Kharbanda, Kusum; Sisson, Joseph H.; Wyatt, Todd A.

    2013-01-01

    Adenosine concentrations are elevated in the lungs of patients with asthma and chronic obstructive pulmonary disease, where it balances between tissue repair and excessive airway remodeling. We previously demonstrated that the activation of the adenosine A2A receptor promotes epithelial wound closure. However, the mechanism by which adenosine-mediated wound healing occurs after cigarette smoke exposure has not been investigated. The present study investigates whether cigarette smoke exposure alters adenosine-mediated reparative properties via its ability to induce a shift in the oxidant/antioxidant balance. Using an in vitro wounding model, bronchial epithelial cells were exposed to 5% cigarette smoke extract, were wounded, and were then stimulated with either 10 μM adenosine or the specific A2A receptor agonist, 5′-(N-cyclopropyl)–carboxamido–adenosine (CPCA; 10 μM), and assessed for wound closure. In a subset of experiments, bronchial epithelial cells were infected with adenovirus vectors encoding human superoxide dismutase and/or catalase or control vector. In the presence of 5% smoke extract, significant delay was evident in both adenosine-mediated and CPCA-mediated wound closure. However, cells pretreated with N-acetylcysteine (NAC), a nonspecific antioxidant, reversed smoke extract–mediated inhibition. We found that cells overexpressing mitochondrial catalase repealed the smoke extract inhibition of CPCA-stimulated wound closure, whereas superoxide dismutase overexpression exerted no effect. Kinase experiments revealed that smoke extract significantly reduced the A2A-mediated activation of cyclic adenosine monophosphate–dependent protein kinase. However, pretreatment with NAC reversed this effect. In conclusion, our data suggest that cigarette smoke exposure impairs A2A-stimulated wound repair via a reactive oxygen species–dependent mechanism, thereby providing a better understanding of adenosine signaling that may direct the development of

  12. Generation of reactive astrocytes from NG2 cells is regulated by sonic hedgehog.

    PubMed

    Honsa, Pavel; Valny, Martin; Kriska, Jan; Matuskova, Hana; Harantova, Lenka; Kirdajova, Denisa; Valihrach, Lukas; Androvic, Peter; Kubista, Mikael; Anderova, Miroslava

    2016-09-01

    NG2 cells, a fourth glial cell type in the adult mammalian central nervous system, produce oligodendrocytes in the healthy nervous tissue, and display wide differentiation potential under pathological conditions, where they could give rise to reactive astrocytes. The factors that control the differentiation of NG2 cells after focal cerebral ischemia (FCI) are largely unknown. Here, we used transgenic Cspg4-cre/Esr1/ROSA26Sortm14(CAG-tdTomato) mice, in which tamoxifen administration triggers the expression of red fluorescent protein (tomato) specifically in NG2 cells and cells derived therefrom. Differentiation potential (in vitro and in vivo) of tomato-positive NG2 cells from control or postischemic brains was determined using the immunohistochemistry, single cell RT-qPCR and patch-clamp method. The ischemic injury was induced by middle cerebral artery occlusion, a model of FCI. Using genetic fate-mapping method, we identified sonic hedgehog (Shh) as an important factor that influences differentiation of NG2 cells into astrocytes in vitro. We also manipulated Shh signaling in the adult mouse brain after FCI. Shh signaling activation significantly increased the number of astrocytes derived from NG2 cells in the glial scar around the ischemic lesion, while Shh signaling inhibition caused the opposite effect. Since Shh signaling modifications did not change the proliferation rate of NG2 cells, we can conclude that Shh has a direct influence on the differentiation of NG2 cells and therefore, on the formation and composition of a glial scar, which consequently affects the degree of the brain damage. GLIA 2016;64:1518-1531.

  13. Reactive Oxygen Species Generation by Lunar Simulants in Simulated Lung Fluid

    NASA Astrophysics Data System (ADS)

    Schoonen, M. A.; Kaur, J.; Rickman, D.

    2015-12-01

    The current interest in human exploration of the Moon and other airless planetary bodies has rekindled research into the harmful effects of Lunar dust on human health. Our team has evaluated the spontaneous formation of Reactive Oxygen Species (ROS; hydroxyl radicals, superoxide, and hydrogen peroxide) of a suite of lunar simulants when dispersed in deionized water. Of these species, hydroxyl radical reacts almost immediately with any biomolecule leading to oxidative damage. Sustained production of OH radical as a result of mineral exposure can initiate or enhance disease. The results in deionized water indicate that mechanical stress and the absence of molecular oxygen and water, important environmental characteristics of the lunar environment, can lead to enhanced production of ROS in general. On the basis of the results with deionized water, a few of the simulants were selected for additional studies to evaluate the formation of hydrogen peroxide, a precursor of hydroxyl radical in Simulated Lung Fluid. These simulants dispersed in deionized water typically produce a maximum in H2O2 within 10 to 40 minutes. However, experiments in SLF show a slow steady increase in H2O2 concentration that has been documented to continue for as long as 7 hours. Control experiments with one simulant demonstrate that the rise in H2O2 depends on the availability of dissolved O2. We speculate that this continuous rise in oxygenated SLF might be a result of metal ion-mediated oxidation of organic components, such as glycine in SLF. Ion-mediated oxidation essentially allows dissolved molecular oxygen to react with dissolved organic compounds by forming a metal-organic complex. Results of separate experiments with dissolved Fe, Ni, and Cu and speciation calculations support this notion.

  14. Measurement of reactive species generated by dielectric barrier discharge in direct contact with water in different atmospheres

    NASA Astrophysics Data System (ADS)

    Kovačević, Vesna V.; Dojčinović, Biljana P.; Jović, Milica; Roglić, Goran M.; Obradović, Bratislav M.; Kuraica, Milorad M.

    2017-04-01

    The formation of hydroxyl radical and long-living chemical species (H2O2, O3, \\text{NO}3- and \\text{NO}2- ) generated in the liquid phase of a water falling film dielectric barrier discharge in dependence on the gas atmosphere (air, nitrogen, oxygen, argon and helium) was studied. The chemical molecular probe dimethyl sulfoxide was employed for quantification of ˙OH, and the influence of hydroxyl radical scavenging on formation of reactive oxygen and nitrogen species was investigated. In addition to liquid analysis, plasma diagnostics was applied to indicate possible reaction pathways of plasma-liquid interaction. The highest ˙OH production rate of 1.19  ×  10-5 mol l-1 s-1 was found when water was treated in oxygen, with a yield of 2.75  ×  10-2 molecules of ˙OH per 100 eV. Formation of hydrogen peroxide in air, nitrogen and argon discharges is determined by recombination reaction of hydroxyl radicals, reaching the highest yield of about 0.7 g kWh-1 when distilled water was treated in argon discharge. Ozone formation was dominant in oxygen and air discharges. Strong acidification along with formation of reactive nitrogen species was detected in water treated in air and nitrogen discharges.

  15. Antiplatelet Aggregation Activity of Walnut Hull Extract via Suppression of Reactive Oxygen Species Generation and Caspase Activation.

    PubMed

    Meshkini, Azadeh; Tahmasbi, Masoumeh

    2017-06-01

    Walnut hull (wal hull) is an agricultural by-product that is widely used in traditional medicine for alleviating pain and treating skin diseases, however, recently it has gained much attention in modern pharmacology due to its antioxidant properties. The current study was aimed to determine the total phenolic, flavonoid, and tannin content of Persian wal hull extract and evaluate its biological effects on platelet function. Experimental data showed that acetone extract of wal hulls has a high content of polyphenolic compounds and antioxidant properties. The analytical study of crude extract by gas chromatography-mass spectrometry demonstrated different types of high- and low-molecular-weight compounds that are basically and biologically important. Moreover, an in vitro study revealed that wal hull extract at a concentration of 50 μg/mL inhibited thrombin-induced platelet aggregation and protein secretion by 50%, without any cytotoxic effects on platelets. The examined extract suppressed reactive oxygen species generation and also caspase activation in thrombin-stimulated platelets. Identically, N-acetylcysteine inhibited the increase of reactive oxygen species level induced by thrombin in platelets, and supported a link between cellular redox status and caspase activation in activated platelets. Presumably, the antiplatelet activity of wal hull extract is related to its polyphenolic compounds and their antioxidant properties. Therefore, wal hulls can be considered as a candidate for thrombotic disorders. Copyright © 2017. Published by Elsevier B.V.

  16. Derivatization of haemoglobin with periodate-generated reticulation agents: evaluation of oxidative reactivity for potential blood substitutes.

    PubMed

    Deac, Florina; Iacob, Bianca; Fischer-Fodor, Eva; Damian, Grigore; Silaghi-Dumitrescu, Radu

    2011-01-01

    Periodate modification of the sugar moiety in sugars, including adenosine triphosphate (ATP), has previously been employed in order to prepare dialdehyde-type reagents, which were then utilized in crosslinking reactions on haemoglobin, yielding polymerized material with useful dioxygen-binding properties and hence proposed as possible artificial oxygen carriers ('blood substitutes'). Here, the periodate protocol is shown to be applicable to a wider range of oxygen-containing compounds, illustrated by starch and polyethylene glycol. Derivatization protocols are described for haemoglobin with such periodate-treated crosslinking agents, and the dioxygen-binding properties and redox reactivities are investigated for the derivatized haemoglobins, with emphasis on pro-oxidative properties. There is a general tendency of the derivatization to result in higher autooxidation rates. The peroxide reactivity of the met (ferric) form is also affected by derivatization, as witnessed, among others, by varying yields of ferryl [Fe (IV)-oxo] and free radical generated. In cell, culture tests (human umbilical vein epithelial cells, HUVEC), the derivatization protocols show no toxic effect.

  17. Intracellular delivery of the reactive oxygen species generating agent D-penicillamine upon conjugation to poly-L-glutamic acid.

    PubMed

    Wadhwa, Saurabh; Mumper, Russell J

    2010-06-07

    D-penicillamine is an aminothiol that is cytotoxic to cancer cells and generates dose dependent reactive oxygen species (ROS) via copper catalyzed oxidation. However, the delivery of D-pen to cancer cells remains a challenge due to its high hydrophilicity, highly reactive thiol group and impermeability to the cell membrane. To overcome this challenge, we investigated a novel poly-L-glutamic acid (PGA) conjugate of D-pen (PGA-D-pen) where D-pen was conjugated to PGA modified with 2-(2-pyridyldithio)-ethylamine (PDE) via disulfide bonds. Confocal microscopy and cell uptake studies showed that the fluorescently labeled PGA-D-pen was taken up by human leukemia cells (HL-60) in a time dependent manner. Treatment of HL-60, murine leukemia cells (P388) and human breast cancer cells (MDA-MB-468) with PGA-D-pen resulted in dose dependent cytotoxicity and elevation of intracellular ROS levels. PGA-D-pen induced apoptosis in HL-60 cells which was verified by Annexin V binding. The in vivo evaluation of the conjugate in the P388 murine leukemia model (intraperitoneal) resulted in significant enhancement in the survival of CD2F1 mice over vehicle control.

  18. Quantitation of cutaneous inflammation induced by reactive species generated by UV-visible irradiation of rose bengal

    SciTech Connect

    Ranadive, N.S.; Menon, I.A.; Shirwadkar, S.; Persad, S.D. )

    1989-10-01

    The present studies were undertaken to quantitate the initial inflammatory response produced by the photo-generated reactive species in rabbit skin. Rose bengal (RB), a photosensitizer dye, was injected into the skin sites at various concentrations and exposed to UV-visible light for 30-120 min. The increase in vascular permeability and the accumulation of PMNs were investigated using 125I-labeled albumin and 51Cr-labeled PMNs. RB at a concentration of 1 nmol with 120-min exposure to light enhanced vascular permeability by 3.7 times and accumulation of PMNs by 3.3 times. As low as 0.01 nmol of RB produced discernible effects. beta-Carotene (0.1 nmole) inhibited the inflammatory response by 75-100%, suggesting that the reactive species involved in this response was predominantly singlet oxygen. The increase in vascular permeability was inhibited by 48-70% by 25 micrograms of chlorpheniramine maleate. It is therefore suggested that histamine plays a major role in the initial vascular response. The studies demonstrate that this rabbit model is suitable for the quantitation of photoinduced inflammatory response which is not observable by gross anatomic procedures.

  19. Xenobiotic induction of quinone oxidoreductase activity in lens epithelial cells.

    PubMed

    Tumminia, S J; Rao, P V; Zigler, J S; Russell, P

    1993-12-08

    Xenobiotic regulatory elements have been identified for enzymes which ameliorate oxidative damage in cells. Zeta (zeta)-crystallin, a taxon-specific enzyme/crystallin shown to be a novel NADPH-dependent quinone reductase, is found in a number of tissues and cell types. This study shows that zeta-crystallin is present in mouse lens epithelium, as well as in the alpha TN4 mouse lens epithelial cell line. To determine whether zeta-crystallin is an inducible quinone reductase, cell cultures were exposed to the xenobiotics, 1,2-naphthoquinone and beta-naphthoflavone. Assays of cellular homogenates showed that quinone reductase activity was stimulated greater than 70% and 90%, respectively, over the control cells. This observed activity was sensitive to dicumarol, a potent inhibitor of quinone reductase activity. 1,2-Naphthoquinone- and beta-naphthoflavone-exposed cells were found to exhibit 1.47- and 1.68-fold increases, respectively, in zeta-crystallin protein concentration. A comparable increase in zeta-crystallin mRNA was indicative of an induction in zeta-crystallin expression in response to naphthalene challenge. Lens epithelial cells were also checked for DT-diaphorase, a well-known cellular protective enzyme which can catalyze the two-electron reduction of quinones. Slot blot analyses indicated that alpha TN4 cells exposed to 1,2-naphthoquinone and beta-naphthoflavone exhibited 2.71- and 6.81-fold increases in DT-diaphorase concentration when compared to the control cells. The data suggest that while DT-diaphorase is most likely responsible for the majority of the observed increase in quinone reductase activity, the zeta-crystallin gene also undergoes activation which is apparently mediated by a xenobiotic-responsive element.

  20. Staphylococcus aureus lactate- and malate-quinone oxidoreductases contribute to nitric oxide resistance and virulence.

    PubMed

    Spahich, Nicole A; Vitko, Nicholas P; Thurlow, Lance R; Temple, Brenda; Richardson, Anthony R

    2016-06-01

    Staphylococcus aureus is a Gram-positive pathogen that resists many facets of innate immunity including nitric oxide (NO·). Staphylococcus aureus NO-resistance stems from its ability to evoke a metabolic state that circumvents the negative effects of reactive nitrogen species. The combination of l-lactate and peptides promotes S. aureus growth at moderate NO-levels, however, neither nutrient alone suffices. Here, we investigate the staphylococcal malate-quinone and l-lactate-quinone oxidoreductases (Mqo and Lqo), both of which are critical during NO-stress for the combined utilization of peptides and l-lactate. We address the specific contributions of Lqo-mediated l-lactate utilization and Mqo-dependent amino acid consumption during NO-stress. We show that Lqo conversion of l-lactate to pyruvate is required for the formation of ATP, an essential energy source for peptide utilization. Thus, both Lqo and Mqo are essential for growth under these conditions making them attractive candidates for targeted therapeutics. Accordingly, we exploited a modelled Mqo/Lqo structure to define the catalytic and substrate-binding residues.We also compare the S. aureus Mqo/Lqo enzymes to their close relatives throughout the staphylococci and explore the substrate specificities of each enzyme. This study provides the initial characterization of the mechanism of action and the immunometabolic roles for a newly defined staphylococcal enzyme family. © 2016 John Wiley & Sons Ltd.

  1. Induction of quinone reductase (QR) by withanolides isolated from Physalis pubescens L. (Solanaceae).

    PubMed

    Ji, Long; Yuan, Yonglei; Ma, Zhongjun; Chen, Zhe; Gan, Lishe; Ma, Xiaoqiong; Huang, Dongsheng

    2013-09-01

    In the present study, it was demonstrated that the dichloromethane extract of Physalis pubescens L. (DEPP) had weak potential quinone reductase (QR) inducing activity, but an UPLC-ESI-MS method with glutathione (GSH) as the substrate revealed that the DEPP had electrophiles (with an α,β-unsaturated ketone moiety). These electrophiles could induce quinone reductase (QR) activity, which might be attributed to the modification of the highly reactive cysteine residues in Keap1. Herein, four withanolides, including three new compounds physapubescin B (2), physapubescin C (3), physapubescin D (4), together with one known steroidal compound physapubescin (1) were isolated. Structures of these compounds were determined by spectroscopic analysis and that of physapubescin C (3) was confirmed by a combination of molecular modeling and quantum chemical DFT-GIAO calculations. Evaluation of the QR inducing activities of all withanolides indicated potent activities of compounds 1 and 2, which had a common α,β-unsaturated ketone moiety. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Michael Additions of Highly Basic Enolates to ortho-Quinone Methides.

    PubMed

    Lewis, Robert S; Garza, Christopher J; Dang, Ann T; Pedro, Te Kie A; Chain, William J

    2015-05-01

    A protocol by which ketone or ester enolates and ortho-quinone methides (o-QMs) are generated in situ in a single reaction flask from silylated precursors under the action of anhydrous fluoride is reported. The reaction partners are joined to give a variety of β-(2-hydroxyphenyl)-carbonyl compounds in 32-94% yield in a single laboratory operation. The intermediacy of o-QMs is supported by control experiments utilizing enolate precursors and conventional alkyl halides as competitive alkylating agents and the isolation of 1,5-dicarbonyl products resulting from conjugate additions that do not restore the aromatic system.

  3. Michael Additions of Highly Basic Enolates to ortho-Quinone Methides

    PubMed Central

    Lewis, Robert S.; Garza, Christopher J.; Dang, Ann T.; Pedro, Te Kie A.; Chain, William J.

    2015-01-01

    A protocol by which ketone or ester enolates and ortho-quinone methides (o-QMs) are generated in situ in a single reaction flask from silylated precursors under the action of anhydrous fluoride is reported. The reaction partners are joined to give a variety of β-(2-hydroxyphenyl)-carbonyl compounds in 32–94% yield in a single laboratory operation. The intermediacy of o-QMs is supported by control experiments utilizing enolate precursors and conventional alkyl halides as competitive alkylating agents and the isolation of 1,5-dicarbonyl products resulting from conjugate additions that do not restore the aromatic system. PMID:25906358

  4. Carbonylated proteins exposed to UVA and to blue light generate reactive oxygen species through a type I photosensitizing reaction.

    PubMed

    Mizutani, Taeko; Sumida, Hijiri; Sagawa, Yuki; Okano, Yuri; Masaki, Hitoshi

    2016-12-01

    Carbonylated proteins (CPs) are generated by the reaction of basic amino acid residues in proteins with aldehyde compounds produced during lipid peroxidation. CPs in the stratum corneum (SC) impact skin conditions such as skin moisture functions including water content and transepidermal water loss (TEWL). In addition, CPs can be frequently seen in the SC from sun-exposed sites compared with sun-protected sites. The aim of this study was to reveal whether CPs could be a generation source of reactive oxygen species (ROS) in the SC following exposure to ultraviolet (UV) radiation and to identify the type of ROS and its generation mechanism. ROS generation was detected using a methyl cypridina luciferin analog (MCLA) chemiluminescence system and an ESR spin-trapping method. CPs in porcine SC, in a keratin film and in bovine serum albumin (BSA) were prepared by reaction with acrolein. Levels of protein carbonylation were quantified by detecting aldehyde residues. CP levels in the SC were increased in a UVA energy-dependent manner. That result suggested that a source of ROS generation existed in the SC initiated and produced the carbonylation of SC proteins. Carbonylated BSA and carbonylated porcine SC sheets exhibited fluorescence spectra at an excitation wavelength of 430nm and an emission wavelength of 520nm. Irradiation of the SC with UVA increased protein carbonylation and the amount of autofluorescence in the SC. ROS generation in the SC caused by UVA and by short-wavelength visible light (blue light, 400-470nm) was detected by the MCLA chemiluminescence system. Artificially carbonylated porcine SCs and keratin films had increases of chemiluminescence intensity after exposure to both light sources as well. The addition of superoxide dismutase to the MCLA system completely abolished the incremental chemiluminescence intensity after both UVA and blue light exposure of the SC. In addition, acrolein-treated BSA gave ESR signals like hydroxyl radicals (OH) converted

  5. A Synthetic High-Spin Oxoiron(IV) Complex: Generation, Spectroscopic Characterization, and Reactivity

    SciTech Connect

    England, J.; Martinho, M; Farquhar, E; Frisch, J; Bominaar, E; Munck, E; Que, L

    2009-01-01

    The high-yield generation of a synthetic high-spin oxoiron(IV) complex, (Fe{sup IV}(O)(TMG{sub 3}tren)){sup 2+} (TMG{sub 3}tren = 1,1,1-tris{l_brace}2-(N2-(1,1,3,3-tetramethylguanidino))ethyl{r_brace}amine), has been achieved by using the very bulky tetradentate TMG{sub 3}tren ligand, in order to both sterically protect the oxoiron(IV) moiety and enforce a trigonal bipyramidal geometry at the iron center, for which an S=2 ground state is favored.

  6. Chlorophyll-quinone photochemical electron transfer in liposomes

    SciTech Connect

    Hurley, J.K.; Castelli, F.; Tollin, G.

    1981-09-01

    A study is described which involves the reduction of electron acceptors (quinones) by photoexcited chlorophyll (Chl). The experimental samples consisted of Chl a (from spinach) incorporated into phosphatidylcholine (either synthetic or from hen egg yolks) liposomes suspended in 10 mM phosphate buffer (pH 7.0). The quinones were either present during liposome formation or added later, depending on their water solubility. The measurement technique employed was laser flash photolysis. Results have provided considerable insight into the ways in which membranes may modify the photochemical properties of Chl by allowing molecular compartmentalization and by permitting cooperative interactions.

  7. Rapid and permanent neuronal inactivation in vivo via subcellular generation of reactive oxygen with the use of KillerRed.

    PubMed

    Williams, Daniel C; Bejjani, Rachid El; Ramirez, Paula Mugno; Coakley, Sean; Kim, Shin Ae; Lee, Hyewon; Wen, Quan; Samuel, Aravi; Lu, Hang; Hilliard, Massimo A; Hammarlund, Marc

    2013-10-31

    Inactivation of selected neurons in vivo can define their contribution to specific developmental outcomes, circuit functions, and behaviors. Here, we show that the optogenetic tool KillerRed selectively, rapidly, and permanently inactivates different classes of neurons in C. elegans in response to a single light stimulus, through the generation of reactive oxygen species (ROS). Ablation scales from individual neurons in single animals to multiple neurons in populations and can be applied to freely behaving animals. Using spatially restricted illumination, we demonstrate that localized KillerRed activation in either the cell body or the axon triggers neuronal degeneration and death of the targeted cell. Finally, targeting KillerRed to mitochondria results in organelle fragmentation without killing the cell, in contrast to the cell death observed when KillerRed is targeted to the plasma membrane. We expect this genetic tool to have wide-ranging applications in studies of circuit function and subcellular responses to ROS.

  8. 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.

  9. Synthesis of SiC/Ag/Cellulose Nanocomposite and Its Antibacterial Activity by Reactive Oxygen Species Generation

    PubMed Central

    Borkowski, Andrzej; Cłapa, Tomasz; Szala, Mateusz; Gąsiński, Arkadiusz; Selwet, Marek

    2016-01-01

    We describe the synthesis of nanocomposites, based on nanofibers of silicon carbide, silver nanoparticles, and cellulose. Silver nanoparticle synthesis was achieved with chemical reduction using hydrazine by adding two different surfactants to obtain a nanocomposite with silver nanoparticles of different diameters. Determination of antibacterial activity was based on respiration tests. Enzymatic analysis indicates oxidative stress, and viability testing was conducted using an epifluorescence microscope. Strong bactericidal activity of nanocomposites was found against bacteria Escherichia coli and Bacillus cereus, which were used in the study as typical Gram-negative and Gram-positive bacteria, respectively. It is assumed that reactive oxygen species generation was responsible for the observed antibacterial effect of the investigated materials. Due to the properties of silicon carbide nanofiber, the obtained nanocomposite may have potential use in technology related to water and air purification. Cellulose addition prevented silver nanoparticle release and probably enhanced bacterial adsorption onto aggregates of the nanocomposite material. PMID:28335299

  10. Newly synthesized bis-benzimidazole compound 8 induces apoptosis, autophagy and reactive oxygen species generation in HeLa cells.

    PubMed

    Chu, Naying; Yao, Guodong; Liu, Yuan; Cheng, Maosheng; Ikejima, Takashi

    2016-09-01

    Compound 8 (C8) is a newly synthesized bis-benzimidazole derivative and exerts significant anti-tumor activity in vitro. Previous studies demonstrated that C8 induced apoptosis and autophagy in human promyelocytic leukemia HL60 cells. However, cytotoxicity study on human peripheral blood mononuclear cells (hPBMC) showed that C8 exhibited less toxicity in normal cells. In this study, the molecular mechanism of C8 on human cervical carcinoma HeLa cells was investigated. The results showed that C8 inhibited the growth of HeLa cells and triggered both apoptotic and autophagic cell death. Subsequent experiment also indicated that reactive oxygen species (ROS) generation was induced in C8-treated HeLa cells. Since ROS scavenger decreased the ratio of apoptotic and autophagic cells, ROS generation contributed to C8-induced apoptosis and autophagy. Furthermore, inhibitors of apoptosis and autophagy also reduced ROS generation, respectively. Autophagy inhibition increased cell growth compared to C8-treated group and attenuated apoptotic cell death, indicating that C8-induced autophagy promoted apoptosis for cell death. However, the percentage of autophagic cells was enhanced when limiting apoptosis process. Taken together, C8 induced ROS-mediated apoptosis and autophagy in HeLa cells, autophagy promoted apoptosis but the former was antagonized by the latter. The data also gave us a new perspective on the anti-tumor effect of C8. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Increased levels of thiols protect antimony unresponsive Leishmania donovani field isolates against reactive oxygen species generated by trivalent antimony

    PubMed Central

    Mandal, G.; Wyllie, S.; Singh, N.; Sundar, S.; Fairlamb, A.H.; Chatterjee, M.

    2012-01-01

    Summary The current trend of antimony (Sb) unresponsiveness in the Indian subcontinent is a major impediment to effective chemotherapy of visceral leishmaniasis (VL). Although contributory mechanisms studied in laboratory raised Sb-R parasites include an up regulation of drug efflux pumps and increased thiols, their role in clinical isolates is not yet substantiated. Accordingly, our objectives were to study the contributory role of thiols in generation of Sb unresponsiveness in clinical isolates. Promastigotes were isolated from VL patients who were either Sb responsive (n = 2) or unresponsive (n = 3). Levels of thiols as measured by HPLC and flow cytometry showed higher basal levels of thiols and a faster rate of thiol regeneration in Sb unresponsive strains as compared with sensitive strains. The effects of antimony on generation of reactive oxygen species (ROS) in normal and thiol depleted conditions as also their H2O2 scavenging activity indicated that in unresponsive parasites, Sb mediated ROS generation was curtailed which could be reversed by depletion of thiols and was accompanied by a higher H2O2 scavenging activity. Higher levels of thiols in Sb unresponsive field isolates from patients with VL protects parasites from Sb mediated oxidative stress, thereby contributing to the antimony resistance phenotype. PMID:17612420

  12. Generation of reactive oxygen species and oxidative stress in Escherichia coli and Staphylococcus aureus by a novel semiconductor catalyst

    NASA Astrophysics Data System (ADS)

    Chow, K. L.; Mak, N. K.; Wong, M. H.; Zhou, X. F.; Liang, Y.

    2011-03-01

    The objective of this study was to investigate antimicrobial mechanisms of a new catalytic material (charge transfer auto oxidation-reduction type catalyst, CT catalyst) that may have great potential for application in water/wastewater treatment. Generation of reactive oxygen species (ROS) in bacteria-free solution, induction of ROS and oxidative damage in bacteria (including E. coli and S. aureus) were examined for the CT catalyst. The results showed that significantly higher ( p < 0.05, via t-test) amount of hydroxyl radicals was generated by the CT catalyst compared with the control, particularly after 6 h of contact time that more than twice of the amount of the control was produced. The generation of ROS in the bacteria was greater under higher pH and temperature levels, which closely related with the oxidative damage in cells. The results indicated that CT catalyst induced oxidative damage in the bacteria might serve as an important mechanism interpreting the anti-microbial function of the CT catalyst.

  13. Dissolution and reactive oxygen species generation of inhaled cemented tungsten carbide particles in artificial human lung fluids

    NASA Astrophysics Data System (ADS)

    Stefaniak, A. B.; Leonard, S. S.; Hoover, M. D.; Virji, M. A.; Day, G. A.

    2009-02-01

    Inhalation of both cobalt (Co) and tungsten carbide (WC) particles is associated with development of hard metal lung disease (HMD) via generation of reactive oxygen species (ROS), whereas Co alone is sufficient to cause asthma via solubilization and hapten formation. We characterized bulk and aerodynamically size-separated W, WC, Co, spray dryer (pre-sintered), and chamfer grinder (post-sintered) powders. ROS generation was measured in the murine RAW 264.7 cell line using electron spin resonance. When dose was normalized to surface area, hydroxyl radical generation was independent of particle size, which suggests that particle surface chemistry may be an important exposure factor. Chamfer grinder particles generated the highest levels of ROS, consistent with the hypothesis that intimate contact of metals is important for ROS generation. In artificial extracellular lung fluid, alkylbenzyldimethylammonium chloride (ABDC), added to prevent mold growth during experiments, did not influence dissolution of Co (44.0±5.2 vs. 48.3±6.4%) however, dissolution was higher (p<0.05) in the absence of phosphate (62.0±5.4 vs. 48.3±6.4%). In artificial macrophage phagolysosomal fluid, dissolution of Co (36.2±10.4%) does not appear to be influenced (p=0.30) by the absence of glycine (29.8±2.1%), phosphate (39.6±8.6%), or ABDC (44.0±10.5%). These results aid in assessing and understanding Co and W inhalation dosimetry.

  14. Coagulation activation is associated with nicotinamide adenine dinucleotide phosphate oxidase-dependent reactive oxygen species generation in hemodialysis patients.

    PubMed

    Cariello, Marica; Simone, Simona; Loverre, Antonia; Gigante, Margherita; Incampo, Francesca; Pietanza, Stefania; Colucci, Mario; Schena, Francesco P; Gesualdo, Loreto; Grandaliano, Giuseppe; Pertosa, Giovanni

    2012-03-01

    This study investigated on (i) the role of gp91(phox)/NOX2 in reactive oxygen species (ROS) generation in hemodialysis (HD) patients, and (ii) the link between clotting activation and ROS production in this setting. The study was performed on peripheral blood mononuclear cells (PBMCs) isolated from HD patients randomized to polysulphon/polyamide (S-group, n=30) or ethylene-vinyl-alcohol (EVAL) membrane (E-group, n=30) treatment and from healthy subjects (control group, n=15). ROS generation was increased in PBMCs of HD patients compared with healthy subjects. S-group showed higher levels of intracellular ROS generation than control, whereas E-group did not. In addition, S-group displayed an increase in nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity compared with E-group and healthy subjects. A further increase in NADPH activity shortly after HD treatment was observed only in S-group. The plasma levels of the prothrombin fragment F1+2, a marker of in vivo clotting activation, were significantly higher in S-group than in E-group. Moreover, a heightened thrombin generation was recorded in the plasma of S-group. Intracellular ROS production correlated with NADPH oxidase activity and coagulation priming in HD patients. The in vitro validation study demonstrated that incubation of PBMCs with activated FX induced a significant increase in intracellular ROS production, superoxide generation, and gp91(phox)/NOX2 expression. The pivotal role of NADPH oxidase in the upregulation of ROS in HD patients makes this enzyme a potential target for therapeutic intervention in the treatment of HD-related oxidative stress. The EVAL membrane, by reducing clotting activation, inhibits gp91(phox)/NOX2-related ROS production in HD patients.

  15. Loading effects of silver oxides upon generation of reactive oxygen species in semiconductor photocatalysis.

    PubMed

    Kohtani, Shigeru; Yoshida, Kazuhiro; Maekawa, Toshiyasu; Iwase, Akihide; Kudo, Akihiko; Miyabe, Hideto; Nakagaki, Ryoichi

    2008-05-28

    Superoxide anion radical (O(2)(-*)) and OH radical generations in suspensions of Ag metal-, Ag(2)O-, or AgO-loaded TiO(2) and BiVO(4) photocatalysts in alkaline conditions (pH 12.0) were examined by means of a luminol chemiluminescence (CL) technique and a spin-trapping fluorescence one in which terephthalic acid reacts with an OH radical to afford the highly fluorescent 2-hydroxyterephthalic acid (TAOH), respectively. The observed luminol CL intensity was remarkably enhanced by the AgO loading on TiO(2) as well as BiVO(4). This can be explained by enhancement of O(2)(-*) production on the AgO-loaded photocatalysts caused by the synergetic effects on the thermocatalytic activity upon the AgO surface and the efficient electron-hole separation at the photocatalyst/AgO interface. On the other hand, loading effects of AgO on the TAOH formation were not so significant compared to those on the CL observation, though the TAOH formation rates for the TiO(2) samples were much larger than those for the BiVO(4) ones by about three orders of magnitude. The properties of O(2)(-*) and OH radical generations on these photocatalysts are discussed on the basis of the luminol CL kinetics and approximate band edge positions of TiO(2), BiVO(4), and silver oxides.

  16. Nanopore formation process in artificial cell membrane induced by plasma-generated reactive oxygen species.

    PubMed

    Tero, Ryugo; Yamashita, Ryuma; Hashizume, Hiroshi; Suda, Yoshiyuki; Takikawa, Hirofumi; Hori, Masaru; Ito, Masafumi

    2016-09-01

    We investigated morphological change of an artificial lipid bilayer membrane induced by oxygen radicals which were generated by non-equilibrium atmospheric pressure plasma. Neutral oxygen species, O((3)Pj) and O2((1)Δg), were irradiated of a supported lipid bilayer existing under a buffer solution at various conditions of dose time and distances, at which the dose amounts of the oxygen species were calculated quantitatively. Observation using an atomic force microscope and a fluorescence microscope revealed that dose of the neutral oxygen species generated nanopores with the diameter of 10-50 nm in a phospholipid bilayer, and finally destructed the bilayer structure. We found that protrusions appeared on the lipid bilayer surface prior to the formation of nanopores, and we attributed the protrusions to the precursor of the nanopores. We propose a mechanism of the pore formation induced by lipid oxidation on the basis of previous experimental and theoretical studies. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Reactive molecular dynamics of network polymers: Generation, characterization and mechanical properties

    NASA Astrophysics Data System (ADS)

    Shankar, Chandrashekar

    The goal of this research was to gain a fundamental understanding of the properties of networks created by the ring opening metathesis polymerization (ROMP) of dicyclopentadiene (DCPD) used in self-healing materials. To this end we used molecular simulation methods to generate realistic structures of DCPD networks, characterize their structures, and determine their mechanical properties. Density functional theory (DFT) calculations, complemented by structural information derived from molecular dynamics simulations were used to reconstruct experimental Raman spectra and differential scanning calorimetry (DSC) data. We performed coarse-grained simulations comparing networks generated via the ROMP reaction process and compared them to those generated via a RANDOM process, which led to the fundamental realization that the polymer topology has a unique influence on the network properties. We carried out fully atomistic simulations of DCPD using a novel algorithm for recreating ROMP reactions of DCPD molecules. Mechanical properties derived from these atomistic networks are in excellent agreement with those obtained from coarse-grained simulations in which interactions between nodes are subject to angular constraints. This comparison provides self-consistent validation of our simulation results and helps to identify the level of detail necessary for the coarse-grained interaction model. Simulations suggest networks can classified into three stages: fluid-like, rubber-like or glass-like delineated by two thresholds in degree of reaction alpha: The onset of finite magnitudes for the Young's modulus, alphaY, and the departure of the Poisson ration from 0.5, alphaP. In each stage the polymer exhibits a different predominant mechanical response to deformation. At low alpha < alphaY it flows. At alpha Y < alpha < alphaP the response is entropic with no change in internal energy. At alpha > alphaP the response is enthalpic change in internal energy. We developed graph theory

  18. Metabolomic Profiling Unravels DNA Adducts in Human Breast That Are Formed from Peroxidase Mediated Activation of Estrogens to Quinone Methides

    PubMed Central

    Gaikwad, Nilesh W.

    2013-01-01

    Currently there are three major hypotheses that have been proposed for estrogen induced carcinogenicity, however exact etiology remains unknown. Based on the chemical logic, studies were undertaken to investigate if estrogens could generate quinone methides in an oxidative environment which then could cause DNA damage in humans. In presence of MnO2 estrogens were oxidized to quinone methides. Surprisingly quinone methides were found to be stable with t1/2 of 20.8 and 4.5 min respectively. Incubation of estrogens with lactoperoxidase (LPO) and H2O2 resulted in formation of respective quinone methides (E1(E2)-QM). Subsequent addition of adenine to the assay mixture lead to trapping of E1(E2)-QM, resulting in formation of adenine adducts of estrogens, E1(E2)-9-N-Ade. Targeted ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) based metabolomic analysis of the breast tissue extracts showed the presence of adenine adducts of estrogens, E1(E2)-9-N-Ade, along with other estrogen related metabolites. Identity of E1(E2)-N-Ade in LPO assay extracts and breast tissue extracts were confirmed by comparing them to pure synthesized E1(E2)-9-N-Ade standards. From these results, it is evident that peroxidase enzymes or peroxidase-like activity in human breast tissue could oxidize estrogens to electrophilic and stable quinone methides in a single step that covalently bind to DNA to form adducts. The error prone repair of the damaged DNA can result in mutation of critical genes and subsequently cancer. This article reports evidence for hitherto unknown estrogen metabolic pathway in human breast, catalyzed by peroxidase, which could initiate cancer. PMID:23762435

  19. Insulin reverses D-glucose-increased nitric oxide and reactive oxygen species generation in human umbilical vein endothelial cells.

    PubMed

    González, Marcelo; Rojas, Susana; Avila, Pía; Cabrera, Lissette; Villalobos, Roberto; Palma, Carlos; Aguayo, Claudio; Peña, Eduardo; Gallardo, Victoria; Guzmán-Gutiérrez, Enrique; Sáez, Tamara; Salsoso, Rocío; Sanhueza, Carlos; Pardo, Fabián; Leiva, Andrea; Sobrevia, Luis

    2015-01-01

    Vascular tone is controlled by the L-arginine/nitric oxide (NO) pathway, and NO bioavailability is strongly affected by hyperglycaemia-induced oxidative stress. Insulin leads to high expression and activity of human cationic amino acid transporter 1 (hCAT-1), NO synthesis and vasodilation; thus, a protective role of insulin on high D-glucose-alterations in endothelial function is likely. Vascular reactivity to U46619 (thromboxane A2 mimetic) and calcitonin gene related peptide (CGRP) was measured in KCl preconstricted human umbilical vein rings (wire myography) incubated in normal (5 mmol/L) or high (25 mmol/L) D-glucose. hCAT-1, endothelial NO synthase (eNOS), 42 and 44 kDa mitogen-activated protein kinases (p42/44mapk), protein kinase B/Akt (Akt) expression and activity were determined by western blotting and qRT-PCR, tetrahydrobiopterin (BH4) level was determined by HPLC, and L-arginine transport (0-1000 μmol/L) was measured in response to 5-25 mmol/L D-glucose (0-36 hours) in passage 2 human umbilical vein endothelial cells (HUVECs). Assays were in the absence or presence of insulin and/or apocynin (nicotinamide adenine dinucleotide phosphate-oxidase [NADPH oxidase] inhibitor), tempol or Mn(III)TMPyP (SOD mimetics). High D-glucose increased hCAT-1 expression and activity, which was biphasic (peaks: 6 and 24 hours of incubation). High D-glucose-increased maximal transport velocity was blocked by insulin and correlated with lower hCAT-1 expression and SLC7A1 gene promoter activity. High D-glucose-increased transport parallels higher reactive oxygen species (ROS) and superoxide anion (O2•-) generation, and increased U46619-contraction and reduced CGRP-dilation of vein rings. Insulin and apocynin attenuate ROS and O2•- generation, and restored vascular reactivity to U46619 and CGRP. Insulin, but not apocynin or tempol reversed high D-glucose-increased NO synthesis; however, tempol and Mn(III)TMPyP reversed the high D-glucose-reduced BH4 level. Insulin and

  20. Insulin Reverses D-Glucose–Increased Nitric Oxide and Reactive Oxygen Species Generation in Human Umbilical Vein Endothelial Cells

    PubMed Central

    González, Marcelo; Rojas, Susana; Avila, Pía; Cabrera, Lissette; Villalobos, Roberto; Palma, Carlos; Aguayo, Claudio; Peña, Eduardo; Gallardo, Victoria; Guzmán-Gutiérrez, Enrique; Sáez, Tamara; Salsoso, Rocío; Sanhueza, Carlos; Pardo, Fabián; Leiva, Andrea; Sobrevia, Luis

    2015-01-01

    Vascular tone is controlled by the L-arginine/nitric oxide (NO) pathway, and NO bioavailability is strongly affected by hyperglycaemia-induced oxidative stress. Insulin leads to high expression and activity of human cationic amino acid transporter 1 (hCAT-1), NO synthesis and vasodilation; thus, a protective role of insulin on high D-glucose–alterations in endothelial function is likely. Vascular reactivity to U46619 (thromboxane A2 mimetic) and calcitonin gene related peptide (CGRP) was measured in KCl preconstricted human umbilical vein rings (wire myography) incubated in normal (5 mmol/L) or high (25 mmol/L) D-glucose. hCAT-1, endothelial NO synthase (eNOS), 42 and 44 kDa mitogen-activated protein kinases (p42/44mapk), protein kinase B/Akt (Akt) expression and activity were determined by western blotting and qRT-PCR, tetrahydrobiopterin (BH4) level was determined by HPLC, and L-arginine transport (0–1000 μmol/L) was measured in response to 5–25 mmol/L D-glucose (0–36 hours) in passage 2 human umbilical vein endothelial cells (HUVECs). Assays were in the absence or presence of insulin and/or apocynin (nicotinamide adenine dinucleotide phosphate-oxidase [NADPH oxidase] inhibitor), tempol or Mn(III)TMPyP (SOD mimetics). High D-glucose increased hCAT-1 expression and activity, which was biphasic (peaks: 6 and 24 hours of incubation). High D-glucose–increased maximal transport velocity was blocked by insulin and correlated with lower hCAT-1 expression and SLC7A1 gene promoter activity. High D-glucose–increased transport parallels higher reactive oxygen species (ROS) and superoxide anion (O2•–) generation, and increased U46619-contraction and reduced CGRP-dilation of vein rings. Insulin and apocynin attenuate ROS and O2•– generation, and restored vascular reactivity to U46619 and CGRP. Insulin, but not apocynin or tempol reversed high D-glucose–increased NO synthesis; however, tempol and Mn(III)TMPyP reversed the high D-glucose–reduced BH4

  1. Redox-active quinones and ascorbate: an innovative cancer therapy that exploits the vulnerability of cancer cells to oxidative stress.

    PubMed

    Verrax, J; Beck, R; Dejeans, N; Glorieux, C; Sid, B; Pedrosa, R Curi; Benites, J; Vásquez, D; Valderrama, J A; Calderon, P Buc

    2011-02-01

    Cancer cells are particularly vulnerable to treatments impairing redox homeostasis. Reactive oxygen species (ROS) can indeed play an important role in the initiation and progression of cancer, and advanced stage tumors frequently exhibit high basal levels of ROS that stimulate cell proliferation and promote genetic instability. In addition, an inverse correlation between histological grade and antioxidant enzyme activities is frequently observed in human tumors, further supporting the existence of a redox dysregulation in cancer cells. This biochemical property can be exploited by using redox-modulating compounds, which represent an interesting approach to induce cancer cell death. Thus, we have developed a new strategy based on the use of pharmacologic concentrations of ascorbate and redox-active quinones. Ascorbate-driven quinone redox cycling leads to ROS formation and provoke an oxidative stress that preferentially kill cancer cells and spare healthy tissues. Cancer cell death occurs through necrosis and the underlying mechanism implies an energetic impairment (ATP depletion) that is likely due to glycolysis inhibition. Additional mechanisms that participate to cell death include calcium equilibrium impairment and oxidative cleavage of protein chaperone Hsp90. Given the low systemic toxicity of ascorbate and the impairment of crucial survival pathways when associated with redox-active quinones, these combinations could represent an original approach that could be combined to standard cancer therapy.

  2. Generation and reactivation of T-cell receptor A joining region pseudogenes in primates

    SciTech Connect

    Thiel, C.; Lanchbury, J.S.; Otting, N.

    1996-06-01

    Tandemly duplicated T-cell receptor (Tcr) AJ (J{alpha}) segments contribute significantly to TCRA chain junctional region diversity in mammals. Since only limited data exists on TCRA diversity in nonhuman primates, we examined the TCRAJ regions of 37 chimpanzee and 71 rhesus macaque TCRA cDNA clones derived from inverse polymerase chain reaction on peripheral blood mononuclear cell cDNA of healthy animals. Twenty-five different TCRAJ regions were characterized in the chimpanzee and 36 in the rhesus macaque. Each bears a close structural relationship to an equivalent human TCRAJ region. Conserved amino acid motifs are shared between all three species. There are indications that differences between nonhuman primates and humans exist in the generation of TCRAJ pseudogenes. The nucleotide and amino acid sequences of the various characterized TCRAJ of each species are reported and we compare our results to the available information on human genomic sequences. Although we provide evidence of dynamic processes modifying TCRAJ segments during primate evolution, their repertoire and primary structure appears to be relatively conserved. 21 refs., 2 figs.

  3. Effect of Structural Transformation of Nanoparticulate Zero-Valent Iron on Generation of Reactive Oxygen Species.

    PubMed

    He, Di; Ma, Jinxing; Collins, Richard N; Waite, T David

    2016-04-05

    While it has been recognized for some time that addition of nanoparticlate zerovalent iron (nZVI) to oxygen-containing water results in both corrosion of Fe(0) and oxidation of contaminants, there is limited understanding of either the relationship between transformation of nZVI and oxidant formation or the factors controlling the lifetime and extent of oxidant production. Using Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy, we show that while nZVI particles are transformed to ferrihydrite then lepidocrocite in less than 2 h, oxidant generation continues for up to 10 h. The major products (Fe(II) and H2O2) of the reaction of nZVI with oxygenated water are associated, for the most part, with the surface of particles present with these surface-associated Fenton reagents inducing oxidation of a target compound (in this study, (14)C-labeled formate). Effective oxidation of formate only occurred after formation of iron oxides on the nZVI surface with the initial formation of high surface area ferrihydrite facilitating rapid and extensive adsorption of formate with colocation of this target compound and surface-associated Fe(II) and H2O2 apparently critical to formate oxidation. Ongoing formate oxidation long after nZVI is consumed combined with the relatively slow consumption of Fe(II) and H2O2 suggest that these reactants are regenerated during the nZVI-initiated heterogeneous Fenton process.

  4. Reactive oxygen species generated by cyanide mediate toxicity in rat pheochromocytoma cells.

    PubMed

    Kanthasamy, A G; Ardelt, B; Malave, A; Mills, E M; Powley, T L; Borowitz, J L; Isom, G E

    1997-09-19

    Peroxide formation has been implicated in impairment of motor function by cyanide which occurs in both animals and man. The present study employs the neuronal model, rat pheochromocytoma (PC12) cells to evaluate peroxidation as a toxic mechanism of cyanide. Confocal imaging shows that peroxides form within a few seconds in cell cytoplasm after cyanide exposure and continue to accumulate over a period of several minutes. Peroxide generation by cyanide is decreased to about 50% by phospholipase A2 inhibitors indicating involvement of arachidonic acid in the oxidative process. Also antioxidant defense enzymes (CuZn superoxide dismutase and especially catalase) in PC12 cells are inhibited by cyanide. It appears that peroxide accumulation after cyanide treatment involves both inhibition of breakdown and increased production. Furthermore, both peroxide accumulation and cell death induced by cyanide in PC12 cells are blocked by an antioxidant (ascorbate). These data support the hypothesis that the cytotoxic action of cyanide is related in part to an oxidative process.

  5. Process for Preparing Microcapsules Having Gelatin Walls Crosslinked with Quinone.

    DTIC Science & Technology

    A process for conveniently producing microcapsules containing a gelatin wall crosslinked with quinone and a core of an active compound such as a...provides microcapsules of excellent strength, storage stability, and resistance to aqueous exposure, such that the rate of release of the fouling reducing agent can be controlled with precision. jg

  6. Synthesis of azobenzenes from quinone acetals and arylhydrazines.

    PubMed

    Carreño, M Carmen; Mudarra, Gerardo Fernández; Merino, Estíbaliz; Ribagorda, María

    2004-05-14

    Direct reaction between quinone bisacetals and arylhydrazines gives azobenzenes. The presence of catalytic amounts of cerium ammonium nitrate strongly accelerates the reaction. When the bisacetal has a substituent at the 2,5-cyclohexadiene framework, only one regioisomer is formed. The method represents a simple, mild, and novel synthetic access to differently substituted azocompounds in high to excellent yield.

  7. Kinetic, thermodynamic and X-ray structural insights into the interaction of melatonin and analogues with quinone reductase 2

    PubMed Central

    CALAMINI, Barbara; SANTARSIERO, Bernard D.; BOUTIN, Jean A.; MESECAR, Andrew D.

    2011-01-01

    Melatonin exerts its biological effects through at least two transmembrane G-protein-coupled receptors, MT1 and MT2, and a lower-affinity cytosolic binding site, designated MT3. MT3 has recently been identified as QR2 (quinone reductase 2) (EC 1.10.99.2) which is of significance since it links the antioxidant effects of melatonin to a mechanism of action. Initially, QR2 was believed to function analogously to QR1 in protecting cells from highly reactive quinones. However, recent studies indicate that QR2 may actually transform certain quinone substrates into more highly reactive compounds capable of causing cellular damage. Therefore it is hypothesized that inhibition of QR2 in certain cases may lead to protection of cells against these highly reactive species. Since melatonin is known to inhibit QR2 activity, but its binding site and mode of inhibition are not known, we determined the mechanism of inhibition of QR2 by melatonin and a series of melatonin and 5-hydroxytryptamine (serotonin) analogues, and we determined the X-ray structures of melatonin and 2-iodomelatonin in complex with QR2 to between 1.5 and 1.8 Å (1 Å =0.1 nm) resolution. Finally, the thermodynamic binding constants for melatonin and 2-iodomelatonin were determined by ITC (isothermal titration calorimetry). The kinetic results indicate that melatonin is a competitive inhibitor against N-methyldihydronicotinamide (Ki = 7.2 μM) and uncompetitive against menadione (Ki = 92 μM), and the X-ray structures shows that melatonin binds in multiple orientations within the active sites of the QR2 dimer as opposed to an allosteric site. These results provide new insights into the binding mechanisms of melatonin and analogues to QR2. PMID:18254726

  8. Kinetic, thermodynamic and X-ray structural insights into the interaction of melatonin and analogues with quinone reductase 2

    SciTech Connect

    Calamini, Barbara; Santarsiero, Bernard D.; Boutin, Jean A.; Mesecar, Andrew D.

    2008-09-12

    Melatonin exerts its biological effects through at least two transmembrane G-protein-coupled receptors, MT1 and MT2, and a lower-affinity cytosolic binding site, designated MT3. MT3 has recently been identified as QR2 (quinone reductase 2) (EC 1.10.99.2) which is of significance since it links the antioxidant effects of melatonin to a mechanism of action. Initially, QR2 was believed to function analogously to QR1 in protecting cells from highly reactive quinones. However, recent studies indicate that QR2 may actually transform certain quinone substrates into more highly reactive compounds capable of causing cellular damage. Therefore it is hypothesized that inhibition of QR2 in certain cases may lead to protection of cells against these highly reactive species. Since melatonin is known to inhibit QR2 activity, but its binding site and mode of inhibition are not known, we determined the mechanism of inhibition of QR2 by melatonin and a series of melatonin and 5-hydroxytryptamine (serotonin) analogues, and we determined the X-ray structures of melatonin and 2-iodomelatonin in complex with QR2 to between 1.5 and 1.8 {angstrom} (1 {angstrom} = 0.1 nm) resolution. Finally, the thermodynamic binding constants for melatonin and 2-iodomelatonin were determined by ITC (isothermal titration calorimetry). The kinetic results indicate that melatonin is a competitive inhibitor against N-methyldihydronicotinamide (K{sub i} = 7.2 {mu}M) and uncompetitive against menadione (K{sub i} = 92 {mu}M), and the X-ray structures shows that melatonin binds in multiple orientations within the active sites of the QR2 dimer as opposed to an allosteric site. These results provide new insights into the binding mechanisms of melatonin and analogues to QR2.

  9. 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

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

    PubMed

    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.

  11. Effect of a reactive oxygen species-generating system for control of airborne microorganisms in a meat-processing environment.

    PubMed

    Patel, J R; Nou, X

    2008-09-01

    The effectiveness of reactive oxygen species (ROS)-generating AirOcare equipment on the reduction of airborne bacteria in a meat-processing environment was determined. Serratia marcescens and lactic acid bacteria (Lactococcus lactis subsp. lactis and Lactobacillus plantarum) were used to artificially contaminate the air via a six-jet Collison nebulizer. Air in the meat-processing room was sampled immediately after aerosol generation and at various predetermined times at multiple locations by using a Staplex 6 stage air sampler. Approximately a 4-log reduction of the aerial S. marcescens population was observed within 2 h of treatment (P < 0.05) compared to a 1-log reduction in control samples. The S. marcescens populations reduced further by approximately 4.5 log after 24 h of exposure to ROS treatment. Approximately 3-log CFU/m3 reductions in lactic acid bacteria were observed following 2-h ROS exposure. Further ROS exposure reduced lactic acid bacteria in the air; however, the difference in their survival after 24 h of exposure was not significantly different from that observed with the control treatment. S. marcescens bacteria were more sensitive to ROS treatment than the lactic acid bacteria. These findings reveal that ROS treatment using the AirOcare unit significantly reduces airborne S. marcescens and lactic acid bacteria in meat-processing environments within 2 h.

  12. Phloretin induces cell cycle arrest and apoptosis of human glioblastoma cells through the generation of reactive oxygen species.

    PubMed

    Liu, Yuanyuan; Fan, Chenghe; Pu, Lv; Wei, Cui; Jin, Haiqiang; Teng, Yuming; Zhao, Mingming; Yu, Albert Cheung Hoi; Jiang, Feng; Shu, Junlong; Li, Fan; Peng, Qing; Kong, Jian; Pan, Bing; Zheng, Lemin; Huang, Yining

    2016-06-01

    Phloretin, a flavonoid present in various plants, has been reported to exert anticarcinogenic effects. However, the mechanism of its chemo-preventive effect on human glioblastoma cells is not fully understood. This study aimed to investigate the molecular mechanism of phloretin and its associated chemo-preventive effect in human glioblastoma cells. The results indicate that phloretin inhibited cell proliferation by inducing cell cycle arrest at the G0-G1 phase and induced apoptosis of human glioblastoma cells. Phloretin-induced cell cycle arrest was associated with increased expression of p27 and decreased expression of cdk2, cdk4, cdk6, cyclinD and cyclinE. Moreover, the PI3K/AKT/mTOR signaling cascades were suppressed by phloretin in a dose-dependent manner. In addition, phloretin triggered the mitochondrial apoptosis pathway and generated reactive oxygen species (ROS). This was accompanied by the up-regulation of Bax, Bak and c-PARP and the down-regulation of Bcl-2. The antioxidant agents N-acetyl-L-cysteine and glutathione weakened the effect of phloretin on glioblastoma cells. In conclusion, these results demonstrate that phloretin exerts potent chemo-preventive activity in human glioblastoma cells through the generation of ROS.

  13. Mitochondrial complex II can generate reactive oxygen species at high rates in both the forward and reverse reactions.

    PubMed

    Quinlan, Casey L; Orr, Adam L; Perevoshchikova, Irina V; Treberg, Jason R; Ackrell, Brian A; Brand, Martin D

    2012-08-03

    Respiratory complex II oxidizes succinate to fumarate as part of the Krebs cycle and reduces ubiquinone in the electron transport chain. Previous experimental evidence suggested that complex II is not a significant contributor to the production of reactive oxygen species (ROS) in isolated mitochondria or intact cells unless mutated. However, we find that when complex I and complex III are inhibited and succinate concentration is low, complex II in rat skeletal muscle mitochondria can generate superoxide or H(2)O(2) at high rates. These rates approach or exceed the maximum rates achieved by complex I or complex III. Complex II generates these ROS in both the forward reaction, with electrons supplied by succinate, and the reverse reaction, with electrons supplied from the reduced ubiquinone pool. ROS production in the reverse reaction is prevented by inhibition of complex II at either the ubiquinone-binding site (by atpenin A5) or the flavin (by malonate), whereas ROS production in the forward reaction is prevented by malonate but not by atpenin A5, showing that the ROS from complex II arises only from the flavin site (site II(F)). We propose a mechanism for ROS production by complex II that relies upon the occupancy of the substrate oxidation site and the reduction state of the enzyme. We suggest that complex II may be an important contributor to physiological and pathological ROS production.

  14. Plumbagin induces apoptosis via the p53 pathway and generation of reactive oxygen species in human osteosarcoma cells.

    PubMed

    Tian, Linqiang; Yin, Delong; Ren, Ye; Gong, Chen; Chen, Anmin; Guo, Feng-Jin

    2012-01-01

    Osteosarcoma, which is the most common primary bone tumor, occurs most frequently in adolescents. A number of studies have indicated that plumbagin (PL) (5-hydroxy-2-methyl-1, 4-naphthoquinone), a compound found in the plants of the Plumbaginaceae and Droseraceae families, possesses anticancer activity. However, its anticancer effects and mechanisms against osteosarcoma have not been explored. To determine the anticancer effect of PL on osteosarcoma cell lines MG-63 and U2OS, cell viability, apoptosis, cell cycle distribution, caspase-3 and caspase-9 activity and intracellular reactive oxygen species (ROS) generation were measured, and Western blot analyses were performed. PL significantly inhibited the growth of osteosarcoma cells, particularly U2OS cells. PL up-regulated the expression of p53 in U2OS cells and p21 in the two osteosarcoma cell lines causing cell cycle arrest by decreasing the expression of murine double minute 2 (MDM2)/cyclin B1 and cyclin D1. Furthermore, PL altered the ratio of Bax/Bcl-2, and may have triggered the mitochondrial apoptotic pathway, resulting in caspase-3 and caspase-9 activation. We also found that PL induced the generation of ROS in osteosarcoma cell lines. To conclude, PL exerted anticancer activity on osteosarcoma cells by inducing pro-apoptotic signaling and modulating the intracellular ROS that causes induction of apoptosis. These effects may relate to the p53 status.

  15. Novel HLA-B27-restricted Epitopes from Chlamydia trachomatis Generated upon Endogenous Processing of Bacterial Proteins Suggest a Role of Molecular Mimicry in Reactive Arthritis*

    PubMed Central

    Alvarez-Navarro, Carlos; Cragnolini, Juan J.; Dos Santos, Helena G.; Barnea, Eilon; Admon, Arie; Morreale, Antonio; López de Castro, José A.

    2013-01-01

    Reactive arthritis (ReA) is an HLA-B27-associated spondyloarthropathy that is triggered by diverse bacteria, including Chlamydia trachomatis, a frequent intracellular parasite. HLA-B27-restricted T-cell responses are elicited against this bacterium in ReA patients, but their pathogenetic significance, autoimmune potential, and relevant epitopes are unknown. High resolution and sensitivity mass spectrometry was used to identify HLA-B27 ligands endogenously processed and presented by HLA-B27 from three chlamydial proteins for which T-cell epitopes were predicted. Fusion protein constructs of ClpC, Na+-translocating NADH-quinone reductase subunit A, and DNA primase were expressed in HLA-B27+ cells, and their HLA-B27-bound peptidomes were searched for endogenous bacterial ligands. A non-predicted peptide, distinct from the predicted T-cell epitope, was identified from ClpC. A peptide recognized by T-cells in vitro, NQRA(330–338), was detected from the reductase subunit. This is the second HLA-B27-restricted T-cell epitope from C. trachomatis with relevance in ReA demonstrated to be processed and presented in live cells. A novel peptide from the DNA primase, DNAP(211–223), was also found. This was a larger variant of a known epitope and was highly homologous to a self-derived natural ligand of HLA-B27. All three bacterial peptides showed high homology with human sequences containing the binding motif of HLA-B27. Molecular dynamics simulations further showed a striking conformational similarity between DNAP(211–223) and its homologous and much more flexible human-derived HLA-B27 ligand. The results suggest that molecular mimicry between HLA-B27-restricted bacterial and self-derived epitopes is frequent and may play a role in ReA. PMID:23867464

  16. Novel HLA-B27-restricted epitopes from Chlamydia trachomatis generated upon endogenous processing of bacterial proteins suggest a role of molecular mimicry in reactive arthritis.

    PubMed

    Alvarez-Navarro, Carlos; Cragnolini, Juan J; Dos Santos, Helena G; Barnea, Eilon; Admon, Arie; Morreale, Antonio; López de Castro, José A

    2013-09-06

    Reactive arthritis (ReA) is an HLA-B27-associated spondyloarthropathy that is triggered by diverse bacteria, including Chlamydia trachomatis, a frequent intracellular parasite. HLA-B27-restricted T-cell responses are elicited against this bacterium in ReA patients, but their pathogenetic significance, autoimmune potential, and relevant epitopes are unknown. High resolution and sensitivity mass spectrometry was used to identify HLA-B27 ligands endogenously processed and presented by HLA-B27 from three chlamydial proteins for which T-cell epitopes were predicted. Fusion protein constructs of ClpC, Na(+)-translocating NADH-quinone reductase subunit A, and DNA primase were expressed in HLA-B27(+) cells, and their HLA-B27-bound peptidomes were searched for endogenous bacterial ligands. A non-predicted peptide, distinct from the predicted T-cell epitope, was identified from ClpC. A peptide recognized by T-cells in vitro, NQRA(330-338), was detected from the reductase subunit. This is the second HLA-B27-restricted T-cell epitope from C. trachomatis with relevance in ReA demonstrated to be processed and presented in live cells. A novel peptide from the DNA primase, DNAP(211-223), was also found. This was a larger variant of a known epitope and was highly homologous to a self-derived natural ligand of HLA-B27. All three bacterial peptides showed high homology with human sequences containing the binding motif of HLA-B27. Molecular dynamics simulations further showed a striking conformational similarity between DNAP(211-223) and its homologous and much more flexible human-derived HLA-B27 ligand. The results suggest that molecular mimicry between HLA-B27-restricted bacterial and self-derived epitopes is frequent and may play a role in ReA.

  17. Plant cell death caused by fungal, bacterial, and viral elicitors: protective effect of mitochondria-targeted quinones.

    PubMed

    Kiselevsky, D B; Frolova, O Yu; Solovyev, A G; Dorokhov, Yu L; Morozov, S Yu; Samuilov, V D

    2014-12-01

    Chitosan (partially deacetylated chitin), a component of fungal cell walls, caused epidermal cell (EC) death in the leaves of pea (Pisum sativum L.) and tobacco Nicotiana tabacum or Nicotiana benthamiana detected by destruction of cell nuclei. The mitochondria-targeted quinone SkQ1 prevented the destruction of EC nuclei induced by chitosan. Chitosan increased and SkQ1 suppressed the activity of protein kinases in N. benthamiana and P. sativum and eliminated the effect of chitosan. Chitosan induced the generation of reactive oxygen species (ROS) in the guard cells (GC) of pea plants. Treatment with chitosan or H2O2 did not cause destruction of GC nuclei; however, it resulted in disruption of the permeability barrier of the plasma membrane detected by propidium iodide fluorescence. Treatment with bacterial lipopolysaccharide but not peptidoglycan caused destruction of pea EC nuclei, which was prevented by SkQ1. Leaves of tobacco plants containing the N gene responsible for resistance to tobacco mosaic virus (TMV) were infiltrated with Agrobacterium tumefaciens cells. These cells contained a genetic construct with the gene of the helicase domain of TMV replicase (p50); its protein product p50 is a target for the N-gene product. As a result, the hypersensitive response (HR) was initiated. The HR manifested itself in the death of leaves and was suppressed by SkQ3. Treatment of tobacco epidermal peels with the A. tumefaciens cells for the p50 gene expression stimulated the destruction of EC nuclei, which was inhibited by SkQ1 or SkQ3. The p50-lacking A. tumefaciens cells did not induce the destruction of EC nuclei. The protective effect of mitochondria-targeted antioxidants SkQ1 and SkQ3 demonstrates the involvement of mitochondria and their ROS in programmed cell death caused by pathogen elicitors.

  18. 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.

  19. Reactive oxygen species generated in the presence of fine pyrite particles and its implication in thermophilic mineral bioleaching.

    PubMed

    Jones, G C; van Hille, R P; Harrison, S T L

    2013-03-01

    In the tank bioleaching process, maximising solid loading and mineral availability, the latter through decreasing particle size, are key to maximising metal extraction. In this study, the effect of particle size distribution on bioleaching performance and microbial growth was studied through applying knowledge based on medical geology research to understand the adverse effects of suspended fine pyrite particles. Small-scale leaching studies, using pyrite concentrate fractions (106-75, 75-25, -25 μm fines), were used to confirm decreasing performance with decreasing particle size (D 50 <40 μm). Under equivalent experimental conditions, the generation of the reactive oxygen species (ROS), hydrogen peroxide and hydroxyl radicals from pyrite was illustrated. ROS generation measured from the different pyrite fractions was found to increase with increasing pyrite surface area loading (1.79-74.01 m(2) L(-1)) and Fe(2+) concentration (0.1-2.8 g L(-1)) in solution. The highest concentration of ROS was measured from the finest fraction of pyrite (0.85 mM) and from the largest concentration of Fe(2+) (0.78 mM). No ROS was detected from solutions containing only Fe(3+) under the same conditions tested. The potential of ROS to inhibit microbial performance under bioleaching conditions was demonstrated. Pyrite-free Sulfolobus metallicus cultures challenged with hydrogen peroxide (0.5-2.5 mM) showed significant decrease in both cell growth and Fe(2+) oxidation rates within the concentration range 1.5-2.5 mM. In combination, the results from this study suggest that conditions of large pyrite surface area loading, coupled with high concentrations of dissolved Fe(2+), can lead to the generation of ROS, resulting in oxidative stress of the microorganisms.

  20. Characterization of estrogen quinone-derived protein adducts and their identification in human serum albumin derived from breast cancer patients and healthy controls.

    PubMed

    Chen, Dar-Ren; Chen, Shou-Tung; Wang, Tzu-Wen; Tsai, Chen-His; Wei, Hz-Han; Chen, Guan-Jie; Yang, Tsung-Chou; Lin, Che; Lin, Po-Hsiung

    2011-05-10

    Both 17β-estradiol-2,3-quinone (E₂-2,3-Q) and 17β-estradiol-3,4-quinone (E₂-3,4-Q) are reactive metabolites of estrogen that are thought to be responsible for the estrogen-induced genotoxicity. The aim of this study was to establish a methodology to analyze estrogen quinone-derived protein adducts and to measure the background levels of these adducts in human serum albumin (Alb) derived from female blood donors in Taiwan. Results from in vitro experiments confirmed that the production of estrogen quinone-derived adducts on serum Alb increased with increased concentration of estrogen quinones. Time-course experiments suggested that both E₂-2,3-Q- and E₂-3,4-Q-derived adducts rapidly reached maximum values at 10 min mark and remained constant thereafter for up to 24 h. Additionally, with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) pretreatment, the production of estrogen quinone-derived protein adducts was detected in human MCF-7 breast cancer cells exposed to estrogen. Co-treatment of a catechol-O-methyl transferase inhibitor further enhanced the production of estrogen quinone-derived adducts in all cases. When we investigated the levels of estrogen quinone-derived adducts in human serum Alb, cysteinyl adducts of E₂-2,3-Q-1-S-Alb, E₂-2,3-Q-4-S-Alb, and E₂-3,4-Q-2-S-Alb were detected in all healthy female controls (n=10) with median levels at 147 (range 14.1-533), 197 (range 30.0-777), and 65.6 (range 17.6-1360) (pmol/g), respectively. We noticed that levels of E₂-2,3-Q-derived adducts were 2-fold greater than those of E₂-3,4-Q-2-S-Alb in controls whereas levels of E₂-3,4-Q-2-S-Alb were 2-fold higher than those of E₂-2,3-Q-derived adducts in patients (n = 20). Additionally, levels of E₂-2,3-Q-4-S-Alb correlated significantly with those of E₂-3,4-Q-2-S-Alb (correlation coefficient r = 0.684-0.850, p < 0.05). Overall, we conclude that cumulative body burden of E₂-3,4-Q is a significant predictor of breast cancer.

  1. 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. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Cell uptake, intracellular distribution, fate and reactive oxygen species generation of polymer brush engineered CeO2-x NPs

    NASA Astrophysics Data System (ADS)

    Qiu, Yuan; Rojas, Elena; Murray, Richard A.; Irigoyen, Joseba; Gregurec, Danijela; Castro-Hartmann, Pablo; Fledderman, Jana; Estrela-Lopis, Irina; Donath, Edwin; Moya, Sergio E.

    2015-04-01

    Cerium Oxide nanoparticles (CeO2-x NPs) are modified with polymer brushes of negatively charged poly (3-sulfopropylmethacrylate) (PSPM) and positively charged poly (2-(methacryloyloxy)ethyl-trimethylammonium chloride) (PMETAC) by Atom Transfer Radical Polymerisation (ATRP). CeO2-x NPs are fluorescently labelled by covalently attaching Alexa Fluor® 488/Fluorescein isothiocyanate to the NP surface prior to polymerisation. Cell uptake, intracellular distribution and the impact on the generation of intracellular Reactive Oxygen Species (ROS) with respect to CeO2-x NPs are studied by means of Raman Confocal Microscopy (CRM), Transmission Electron Microscopy (TEM) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). PSPM and PMETAC coated CeO2-x NPs show slower and less uptake compared to uncoated Brush modified NPs display a higher degree of co-localisation with cell endosomes and lysosomes after 24 h of incubation. They also show higher co-localisation with lipid bodies when compared to unmodified CeO2-x NPs. The brush coating does not prevent CeO2-x NPs from displaying antioxidant properties.Cerium Oxide nanoparticles (CeO2-x NPs) are modified with polymer brushes of negatively charged poly (3-sulfopropylmethacrylate) (PSPM) and positively charged poly (2-(methacryloyloxy)ethyl-trimethylammonium chloride) (PMETAC) by Atom Transfer Radical Polymerisation (ATRP). CeO2-x NPs are fluorescently labelled by covalently attaching Alexa Fluor® 488/Fluorescein isothiocyanate to the NP surface prior to polymerisation. Cell uptake, intracellular distribution and the impact on the generation of intracellular Reactive Oxygen Species (ROS) with respect to CeO2-x NPs are studied by means of Raman Confocal Microscopy (CRM), Transmission Electron Microscopy (TEM) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). PSPM and PMETAC coated CeO2-x NPs show slower and less uptake compared to uncoated Brush modified NPs display a higher degree of co-localisation with cell

  3. Reactive Power Compensation Method Considering Minimum Effective Reactive Power Reserve

    NASA Astrophysics Data System (ADS)

    Gong, Yiyu; Zhang, Kai; Pu, Zhang; Li, Xuenan; Zuo, Xianghong; Zhen, Jiao; Sudan, Teng

    2017-05-01

    According to the calculation model of minimum generator reactive power reserve of power system voltage stability under the premise of the guarantee, the reactive power management system with reactive power compensation combined generator, the formation of a multi-objective optimization problem, propose a reactive power reserve is considered the minimum generator reactive power compensation optimization method. This method through the improvement of the objective function and constraint conditions, when the system load growth, relying solely on reactive power generation system can not meet the requirement of safe operation, increase the reactive power reserve to solve the problem of minimum generator reactive power compensation in the case of load node.

  4. Combustion-derived flame generated ultrafine soot generates reactive oxygen species and activates Nrf2 antioxidants differently in neonatal and adult rat lungs

    PubMed Central

    2013-01-01

    Background Urban particulate matter (PM) has been epidemiologically correlated with multiple cardiopulmonary morbidities and mortalities, in sensitive populations. Children exposed to PM are more likely to develop respiratory infections and asthma. Although PM originates from natural and anthropogenic sources, vehicle exhaust rich in polycyclic aromatic hydrocarbons (PAH) can be a dominant contributor to the PM2.5 and PM0.1 fractions and has been implicated in the generation of reactive oxygen species (ROS). Objectives Current studies of ambient PM are confounded by the variable nature of PM, so we utilized a previously characterized ethylene-combusted premixed flame particles (PFP) with consistent and reproducible physiochemical properties and 1) measured the oxidative potential of PFP compared to ambient PM, 2) determined the ability of PFPs to generate oxidative stress and activate the transcription factor using in vitro and ex vivo models, and 3) we correlated these responses with antioxidant enzyme expression in vivo. Methods We compared oxidative stress response (HMOX1) and antioxidant enzyme (SOD1, SOD2, CAT, and PRDX6) expression in vivo by performing a time-course study in 7-day old neonatal and young adult rats exposed to a single 6-hour exposure to 22.4 μg/m3 PFPs. Results We showed that PFP is a potent ROS generator that induces oxidative stress and activates Nrf2. Induction of the oxidative stress responsive enzyme HMOX1 in vitro was mediated through Nrf2 activation and was variably upregulated in both ages. Furthermore, antioxidant enzyme expression had age and lung compartment variations post exposure. Of particular interest was SOD1, which had mRNA and protein upregulation in adult parenchyma, but lacked a similar response in neonates. Conclusions We conclude that PFPs are effective ROS generators, comparable to urban ambient PM2.5, that induce oxidative stress in neonatal and adult rat lungs. PFPs upregulate a select set of antioxidant enzymes in

  5. A mutation in the mitochondrial protein UQCRB promotes angiogenesis through the generation of mitochondrial reactive oxygen species

    SciTech Connect

    Chang, Junghwa; Jung, Hye Jin; Jeong, Seung Hun; Kim, Hyoung Kyu; Han, Jin; Kwon, Ho Jeong

    2014-12-12

    Highlights: • We constructed mitochondrial protein UQCRB mutant stable cell lines on the basis of a human case report. • These mutant cell lines exhibit pro-angiogenic activity with enhanced VEGF expression. • Proliferation of mutant cell lines was regulated by UQCRB inhibitors. • UQCRB may have a functional role in angiogenesis. - Abstract: Ubiquinol-cytochrome c reductase binding protein (UQCRB) is one of the subunits of mitochondrial complex III and is a target protein of the natural anti-angiogenic small molecule terpestacin. Previously, the biological role of UQCRB was thought to be limited to the maintenance of complex III. However, the identification and validation of UQCRB as a target protein of terpestacin enabled the role of UQCRB in oxygen sensing and angiogenesis to be elucidated. To explore the biological role of this protein further, UQCRB mutant stable cell lines were generated on the basis of a human case report. We demonstrated that these cell lines exhibited glycolytic and pro-angiogenic activities via mitochondrial reactive oxygen species (mROS)-mediated HIF1 signal transduction. Furthermore, a morphological abnormality in mitochondria was detected in UQCRB mutant stable cell lines. In addition, the proliferative effect of the UQCRB mutants was significantly regulated by the UQCRB inhibitors terpestacin and A1938. Collectively, these results provide a molecular basis for UQCRB-related biological processes and reveal potential key roles of UQCRB in angiogenesis and mitochondria-mediated metabolic disorders.

  6. Tumor necrosis factor-α receptor 1 contributes to ethanol-induced vascular reactive oxygen species generation and hypertension.

    PubMed

    Simplicio, Janaina A; Gonzaga, Natália A; Nakashima, Marcelo A; De Martinis, Bruno S; Cunha, Thiago M; Tirapelli, Luis F; Tirapelli, Carlos R

    2017-07-22

    We evaluated the contribution of tumor necrosis factor-α receptor 1 (TNFR1) to ethanol-induced hypertension and vascular oxidative stress and the possible role of perivascular adipose tissue (PVAT) in such responses. Male C57BL/6 wild-type (WT) or TNFR1-deficient mice (TNFR1(-/-)) were treated with ethanol (20% vol/vol) for 12 weeks. Ethanol induced an increase in blood pressure in WT mice and TNFR1(-/-) at 4 and 5 weeks of treatment, respectively. Treatment with ethanol increased tumor necrosis factor-α and interleukin-6 levels in aortas with or without PVAT (PVAT+ and PVAT-, respectively) from WT mice, but not TNFR1(-/-). Ethanol increased superoxide anion (O2(-)) generation, thiobarbituric acid reactive substance concentration, and the activity of superoxide dismutase and catalase in aortas (PVAT- and PVAT+) from WT mice, but not TNFR1(-/-). Conversely, ethanol consumption decreased the concentration of nitrate/nitrite in aortas (PVAT- and PVAT+) from WT mice, but not TNFR1(-/-). Treatment with ethanol increased myeloperoxidase activity in aortas (PVAT- and PVAT+) from WT mice, but not TNFR1(-/-). The major finding of our study is that TNFR1 contributes to ethanol-induced hypertension and oxidative stress in the vasculature. Additionally, TNFR1 plays a role in ethanol-induced increase in proinflammatory cytokines and neutrophils migration. However, PVAT does not counteract or aggravate the effects induced by ethanol. Copyright © 2017 American Society of Hypertension. Published by Elsevier Inc. All rights reserved.

  7. Induction of apoptosis by three marine algae through generation of reactive oxygen species in human leukemic cell lines.

    PubMed

    Huang, Huey-Lan; Wu, Shwu-Li; Liao, Hui-Fen; Jiang, Chii-Ming; Huang, Ray-Ling; Chen, Yu-Yawn; Yang, Yuh-Cheng; Chen, Yu-Jen

    2005-03-09

    In this study, we examined the antitumor effect of marine algae extracts on human hepatoma and leukemia cells. Ethyl acetate extracts from Colpomenia sinuosa (Cs-EA), Halimeda discoidae (Hd-EA), and Galaxaura oblongata (Go-EA) directly inhibited the growth of human hepatoma HuH-7 cells and leukemia U937 and HL-60 cells in a time- and dose-dependent manner. Specifically, these algae extracts induced apoptosis of U937 and HL-60 cells as evaluated by detection of hypodiploid cells using flow cytometry and observation of condensed and fragmented nuclei in algae extract-treated cells. Intracellular reactive oxygen species (ROS), especially hydrogen peroxide and superoxide anion, were increased about 2-3-fold in U937 cells treated with Cs-EA for 3-5 h. Interestingly, antioxidant N-acetylcysteine effectively blocked Cs-EA-, Hd-EA-, and Go-EA-induced apoptosis, suggesting that ROS is a key mediator in the apoptotic signaling pathway. In conclusion, our results show that algae extracts induce apoptosis in human leukemia cells through generation of ROS.

  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. Curcumin induces heme oxygenase 1 through generation of reactive oxygen species, p38 activation and phosphatase inhibition.

    PubMed

    McNally, Stephen J; Harrison, Ewen M; Ross, James A; Garden, O James; Wigmore, Stephen J

    2007-01-01

    Curcumin is a naturally occurring compound which is known to induce heme oxygenase 1 (HO-1), although the underlying mechanism has not been fully elucidated. This study investigates in detail the mechanism of HO-1 induction by curcumin in human hepatoma cells. There was increasing toxicity of curcumin at concentrations higher than 10 microM. Curcumin was found to induce HO-1 at doses of 10 to 25 microM. At both non-toxic and toxic doses, HO-1 induction was found to correlate with production of reactive oxygen species (ROS), suggesting a causative relationship. This was reinforced by the finding that pretreatment with the antioxidants N-acetylcysteine, vitamin E and catalase prevented HO-1 induction by curcumin. ROS production appeared to be mitochondrial in origin, and curcumin treatment resulted in depolarisation of the mitochondrial membrane potential. Nrf2 was induced by curcumin treatment, which was also partly ROS dependent. Using siRNA, Nrf2 was demonstrated to contribute to HO-1 induction. A panel of kinase inhibitors was used to examine the contribution of MAP kinases to the induction of HO-1 by curcumin. PKC and p38 MAPK activity are required for full induction of HO-1. Furthermore, curcumin also inhibited protein phosphatase activity. In conclusion, curcumin treatment results in ROS generation, activation of Nrf2 and MAP kinases and the inhibition of phosphatase activity in hepatocytes, and when curcumin is not administered in toxic doses, these multiple pathways converge to induce HO-1.

  10. Heat shock protein 75 (TRAP1) antagonizes reactive oxygen species generation and protects cells from granzyme M-mediated apoptosis.

    PubMed

    Hua, Guoqiang; Zhang, Qixiang; Fan, Zusen

    2007-07-13

    Natural killer (NK) cells play an important role in innate immunity against virally infected or transformed cells as the first defense line. Granzyme M (GzmM) is an orphan granzyme that is constitutively highly expressed in NK cells and is consistent with NK cell-mediated cytolysis. We recently demonstrated that GzmM induces caspase-dependent apoptosis with DNA fragmentation through direct cleavage of inhibitor of caspase-activated DNase (ICAD). However, the molecular mechanisms for GzmM-induced apoptosis are unclear. We found GzmM causes mitochondrial swelling and loss of mitochondrial transmembrane potential. Moreover, GzmM initiates reactive oxygen species (ROS) generation and cytochrome c release. Heat shock protein 75 (HSP75, also known as TRAP1) acts as an antagonist of ROS and protects cells from GzmM-mediated apoptosis. GzmM cleaves TRAP1 and abolishes its antagonistic function to ROS, resulting in ROS accumulation. Silencing TRAP1 through RNA interference increases ROS accumulation, whereas TRAP1 overexpression attenuates ROS production. ROS accumulation is in accordance with the release of cytochrome c from mitochondria and enhances GzmM-mediated apoptosis.

  11. Intracellular fragmentation of bone resorption products by reactive oxygen species generated by osteoclastic tartrate-resistant acid phosphatase.

    PubMed

    Halleen, J M; Räisänen, S; Salo, J J; Reddy, S V; Roodman, G D; Hentunen, T A; Lehenkari, P P; Kaija, H; Vihko, P; Väänänen, H K

    1999-08-13

    Tartrate-resistant acid phosphatase (TRAP) is highly expressed in bone-resorbing osteoclasts and activated macrophages. It has been suggested that a redox-active iron in the binuclear iron center of TRAP could have the capacity to react with hydrogen peroxide to produce highly destructive reactive oxygen species (ROS). Here we show that TRAP can generate ROS in vitro and that cells over-expressing TRAP produce higher amounts of intracellular ROS than their parent cells. We further demonstrate that these ROS can be targeted to destroy collagen and other proteins. In resorbing osteoclasts, TRAP was found in transcytotic vesicles transporting matrix degradation products through the cell, suggesting that TRAP-facilitated fragmentation of endocytosed material takes place in a specific cellular compartment. These results suggest that bone matrix degradation occurs not only extracellularly in the resorption lacunae but also intracellularly in the transcytotic vesicles. We propose that proteins containing redox-active iron could represent a novel mechanism of physiological fragmentation of organic molecules. This mechanism could be important in tissue remodeling and as a defense mechanism of phagocytosing cells.

  12. DhARO4 induction and tyrosine nitration in response to reactive radicals generated by salt stress in Debaryomyces hansenii.

    PubMed

    Calderón-Torres, Marissa; Castro, Daniela E; Montero, Paloma; Peña, Antonio

    2011-10-01

    It has been previously reported that growth of Debaryomyces hansenii in 2 M NaCl induced the expression of ARO4. This gene codifies for DhAro4p, involved in the synthesis of the amino acid tyrosine. In this work we studied the activity of DhAro4p upon salt stress; a higher activity was observed in cells grown with 2 M NaCl, but tyrosine levels were not increased. On the other hand, the addition of tyrosine to the saline medium significantly enhanced the growth of D. hansenii. It was found that the oxidized form of tyrosine, 3-nitrotyrosine, increased in the presence of salt. Since NaCl protects against oxidative stress in D. hansenii (Navarrete et al., 2009), we propose that a protective pathway is the de novo synthesis of tyrosine and its immediate oxidation to 3-nitrotyrosine to counteract oxidative stress generated by salt stress, so we measured the production of reactive oxygen species (ROS) and nitric oxide (NO⁻) in D. hansenii after growing in 2 M NaCl. Results showed the presence of NO⁻ and the increased production of ROS; this is probably due to an increased respiratory activity in the cells grown in the presence of salt. Our results demonstrate that upon salt stress D hansenii responds to oxidative stress via the transcriptional activation of specific genes such as DhARO4. Copyright © 2011 John Wiley & Sons, Ltd.

  13. Physalis angulata induces death of promastigotes and amastigotes of Leishmania (Leishmania) amazonensis via the generation of reactive oxygen species.

    PubMed

    Da Silva, B J M; Da Silva, R R P; Rodrigues, A P D; Farias, L H S; Do Nascimento, J L M; Silva, E O

    2016-03-01

    Leishmaniasis are a neglected group of emerging diseases that have been found in 98 countries and are caused by protozoa of the genus Leishmania. The therapy for leishmaniasis causes several side effects and leads to drug-resistant strains. Natural products from plants have exhibited activities against Leishmania in various experimental models. Physalis angulata is a widely used plant in popular medicine, and in the literature it has well-documented leishmanicidal activity. However, its mechanism of action is still unknown. Thus, this study aims to evaluate the mechanism driving the leishmanicidal activity of an aqueous extract of P. angulata root (AEPa). AEPa was effective against both promastigotes and intracellular amastigote forms of Leishmania amazonensis. This effect was mediated by an increase of reactive oxygen species (ROS), but not of nitric oxide (NO). The increased production of ROS induces cell death by phenotypes seems by apoptosis cell death in Leishmania, but not autophagy or necrosis. In addition, morphological analysis of macrophages showed that AEPa induced a high number of cytoplasmic projections, increased the volume of cytoplasm and number of vacuoles, caused cytoskeleton alterations and resulted in high spreading ability. AEPa also promoted superoxide anion (O2(-)) production in both uninfected macrophages and those infected with Leishmania. Therefore, these results revealed that AEPa causes cell death by phenotypes seems by apoptosis cell death in L. amazonensis and modulates macrophage activation through morphofunctional alterations and O2(-) generation to induce Leishmania death. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Low-Level Laser Therapy Activates NF-kB via Generation of Reactive Oxygen Species in Mouse Embryonic Fibroblasts

    PubMed Central

    Huang, Ying-Ying; Tomkinson, Elizabeth M.; Sharma, Sulbha K.; Kharkwal, Gitika B.; Saleem, Taimur; Mooney, David; Yull, Fiona E.; Blackwell, Timothy S.; Hamblin, Michael R.

    2011-01-01

    Background Despite over forty years of investigation on low-level light therapy (LLLT), the fundamental mechanisms underlying photobiomodulation at a cellular level remain unclear. Methodology/Principal Findings In this study, we isolated murine embryonic fibroblasts (MEF) from transgenic NF-kB luciferase reporter mice and studied their response to 810 nm laser radiation. Significant activation of NF-kB was observed at fluences higher than 0.003 J/cm2 and was confirmed by Western blot analysis. NF-kB was activated earlier (1 hour) by LLLT compared to conventional lipopolysaccharide treatment. We also observed that LLLT induced intracellular reactive oxygen species (ROS) production similar to mitochondrial inhibitors, such as antimycin A, rotenone and paraquat. Furthermore, we observed similar NF-kB activation with these mitochondrial inhibitors. These results, together with inhibition of laser induced NF-kB activation by antioxidants, suggests that ROS play an important role in the laser induced NF-kB signaling pathways. However, LLLT, unlike mitochondrial inhibitors, induced increased cellular ATP levels, which indicates that LLLT also upregulates mitochondrial respiration. Conclusion We conclude that LLLT not only enhances mitochondrial respiration, but also activates the redox-sensitive NFkB signaling via generation of ROS. Expression of anti-apoptosis and pro-survival genes responsive to NFkB could explain many clinical effects of LLLT. PMID:21814580

  15. Methodological considerations of electron spin resonance spin trapping techniques for measuring reactive oxygen species generated from metal oxide nanomaterials

    NASA Astrophysics Data System (ADS)

    Jeong, Min Sook; Yu, Kyeong-Nam; Chung, Hyun Hoon; Park, Soo Jin; Lee, Ah Young; Song, Mi Ryoung; Cho, Myung-Haing; Kim, Jun Sung

    2016-05-01

    Qualitative and quantitative analyses of reactive oxygen species (ROS) generated on the surfaces of nanomaterials are important for understanding their toxicity and toxic mechanisms, which are in turn beneficial for manufacturing more biocompatible nanomaterials in many industrial fields. Electron spin resonance (ESR) is a useful tool for detecting ROS formation. However, using this technique without first considering the physicochemical properties of nanomaterials and proper conditions of the spin trapping agent (such as incubation time) may lead to misinterpretation of the resulting data. In this report, we suggest methodological considerations for ESR as pertains to magnetism, sample preparation and proper incubation time with spin trapping agents. Based on our results, each spin trapping agent should be given the proper incubation time. For nanomaterials having magnetic properties, it is useful to remove these nanomaterials via centrifugation after reacting with spin trapping agents. Sonication for the purpose of sample dispersion and sample light exposure should be controlled during ESR in order to enhance the obtained ROS signal. This report will allow researchers to better design ESR spin trapping applications involving nanomaterials.

  16. Generation of reactive species and fate of thiols during peroxidase-catalyzed metabolic activation of aromatic amines and phenols

    SciTech Connect

    Ross, D.; Moldeus, P.

    1985-12-01

    The horseradish peroxidase (HRP)-catalyzed oxidation of p-phenetidine and acetaminophen was investigated. Studies using the spin probe 2-ethyl-1-hydroxy-2,5,5-trimethyl-3-oxazolidine (OXANOH) suggested these oxidations involve the generation of substrate-derived free radicals. This was confirmed by using glutathione (GSH) in these incubations in the presence of the spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), DMPO-glutathionyl radical adducts were observed using EPR spectroscopy during HRP-catalyzed oxidation of both p-phenetidine and acetaminophen. Investigations of oxygen uptake and oxidized glutathione (GSSG) formation during HRP-catalyzed oxidations of p-phenetidine and acetaminophen suggested that further reactions of the glutathionyl radical involve glutathione peroxysulfenyl radical and glutathione sulfenyl hydroperoxide production. Quinonoid products of the peroxidatic oxidations of p-phenetidine and acetaminophen, and their interaction with GSH via both conjugation and redox mechanisms are described. The relevance of these reactions of GSH with reactive species as detoxification mechanisms is discussed. 29 references.

  17. Phototoxicity of nano titanium dioxides in HaCaT keratinocytes--generation of reactive oxygen species and cell damage.

    PubMed

    Yin, Jun-Jie; Liu, Jun; Ehrenshaft, Marilyn; Roberts, Joan E; Fu, Peter P; Mason, Ronald P; Zhao, Baozhong

    2012-08-15

    Nano-sized titanium dioxide (TiO(2)) is among the top five widely used nanomaterials for various applications. In this study, we determine the phototoxicity of TiO(2) nanoparticles (nano-TiO(2)) with different molecular sizes and crystal forms (anatase and rutile) in human skin keratinocytes under UVA irradiation. Our results show that all nano-TiO(2) particles caused phototoxicity, as determined by the MTS assay and by cell membrane damage measured by the lactate dehydrogenase (LDH) assay, both of which were UVA dose- and nano-TiO(2) dose-dependent. The smaller the particle size of the nano-TiO(2) the higher the cell damage. The rutile form of nano-TiO(2) showed less phototoxicity than anatase nano-TiO(2). The level of photocytotoxicity and cell membrane damage is mainly dependent on the level of reactive oxygen species (ROS) production. Using polyunsaturated lipids in plasma membranes and human serum albumin as model targets, and employing electron spin resonance (ESR) oximetry and immuno-spin trapping as unique probing methods, we demonstrated that UVA irradiation of nano-TiO(2) can induce significant cell damage, mediated by lipid and protein peroxidation. These overall results suggest that nano-TiO(2) is phototoxic to human skin keratinocytes, and that this phototoxicity is mediated by ROS generated during UVA irradiation. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. 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.

  19. Efficacy of doxorubicin-transferrin conjugate in apoptosis induction in human leukemia cells through reactive oxygen species generation.

    PubMed

    Szwed, Marzena; Laroche-Clary, Audrey; Robert, Jacques; Jozwiak, Zofia

    2016-04-01

    Doxorubicin (DOX) is a small molecular cytotoxic agent that can be transferred efficiently to cancer cells by nanocarriers. This anthracycline antibiotic serves as an effective anti-neoplastic drug against both hematological and solid malignancies. Here, we set out to assess the capacity of a novel doxorubicin - transferrin conjugate (DOX-TRF) to provoke apoptosis in human normal and leukemia cells through free radicals produced via a redox cycle of doxorubicin (DOX) when released from its conjugate. After DOX-TRF exposure, we determined the time-course of apoptotic and necrotic events, the generation of reactive oxygen species (ROS), changes in mitochondrial membrane potential, as well as alterations in cytochrome c levels and intracellular calcium concentrations in human leukemia-derived cell lines (CCRF-CEM, K562 and its doxorubicin-resistant derivative K562/DOX) and normal peripheral blood-derived mononuclear cells (PBMC). We found that DOX-TRF can induce apoptosis in all leukemia-derived cell lines tested, which was associated with morphological changes and decreases in mitochondrial membrane potential. In comparison to free DOX treated cells, we observed a time-dependency between a higher level of ROS generation and a higher drop in mitochondrial membrane potential, particularly in the doxorubicin-resistant cell line. In addition, we found that the apoptotic cell death induced by DOX-TRF was directly associated with a release of cytochrome c from the mitochondria and an increase in intracellular calcium level in all human leukemia-derived cell lines tested. Our data indicate that DOX-TRF is considerably more cytotoxic to human leukemia cells than free DOX. In addition, we show that DOX-TRF can effectively produce free radicals, which are directly involved in apoptosis induction.

  20. Organic aerosols associated with the generation of reactive oxygen species (ROS) by water-soluble PM2.5.

    PubMed

    Verma, Vishal; Fang, Ting; Xu, Lu; Peltier, Richard E; Russell, Armistead G; Ng, Nga Lee; Weber, Rodney J

    2015-04-07

    We compare the relative toxicity of various organic aerosol (OA) components identified by an aerosol mass spectrometer (AMS) based on their ability to generate reactive oxygen species (ROS). Ambient fine aerosols were collected from urban (three in Atlanta, GA and one in Birmingham, AL) and rural (Yorkville, GA and Centerville, AL) sites in the Southeastern United States. The ROS generating capability of the water-soluble fraction of the particles was measured by the dithiothreitol (DTT) assay. Water-soluble PM extracts were further separated into the hydrophobic and hydrophilic fractions using a C-18 column, and both fractions were analyzed for DTT activity and water-soluble metals. Organic aerosol composition was measured at selected sites using a high-resolution time-of-flight AMS. Positive matrix factorization of the AMS spectra resolved the organic aerosol into isoprene-derived OA (Isop_OA), hydrocarbon-like OA (HOA), less-oxidized oxygenated OA, (LO-OOA), more-oxidized OOA (MO-OOA), cooking OA (COA), and biomass burning OA (BBOA). The association of the DTT activity of water-soluble PM2.5 (WS_DTT) with these factors was investigated by linear regression techniques. BBOA and MO-OOA were most consistently linked with WS_DTT, with intrinsic water-soluble activities of 151 ± 20 and 36 ± 22 pmol/min/μg, respectively. Although less toxic, MO-OOA was most widespread, contributing to WS_DTT activity at all sites and during all seasons. WS_DTT activity was least associated with biogenic secondary organic aerosol. The OA components contributing to WS_DTT were humic-like substances (HULIS), which are abundantly emitted in biomass burning (BBOA) and include highly oxidized OA from multiple sources (MO-OOA). Overall, OA contributed approximately 60% to the WS_DTT activity, with the remaining probably from water-soluble metals, which were mostly associated with the hydrophilic WS_DTT fraction.

  1. Reactive Oxygen Species Generated by NADPH Oxidases Promote Radicle Protrusion and Root Elongation during Rice Seed Germination

    PubMed Central

    Li, Wen-Yan; Chen, Bing-Xian; Chen, Zhong-Jian; Gao, Yin-Tao; Chen, Zhuang; Liu, Jun

    2017-01-01

    Seed germination is a complicated biological process that requires regulation through various enzymatic and non-enzymatic mechanisms. Although it has been recognized that reactive oxygen species (ROS) regulate radicle emergence and root elongation in a non-enzymatic manner during dicot seed germination, the role of ROS in monocot seed germination remains unknown. NADPH oxidases (NOXs) are the major ROS producers in plants; however, whether and how NOXs regulate rice seed germination through ROS generation remains unclear. Here, we report that diphenyleneiodinium (DPI), a specific NOX inhibitor, potently inhibited embryo and seedling growth—especially that of the radicle and of root elongation—in a dose-dependent manner. Notably, the DPI-mediated inhibition of radicle and root growth could be eliminated by transferring seedlings from DPI to water. Furthermore, ROS production/accumulation during rice seed germination was quantified via histochemistry. Superoxide radicals (O2−), hydrogen peroxide (H2O2) and hydroxyl radicals (•OH) accumulated steadily in the coleorhiza, radicle and seedling root of germinating rice seeds. Expression profiles of the nine typical NOX genes were also investigated. According to quantitative PCR, OsNOX5, 7 and 9 were expressed relatively higher. When seeds were incubated in water, OsNOX5 expression progressively increased in the embryo from 12 to 48 h, whereas OsNOX7 and 9 expressions increased from 12 to 24 h and decreased thereafter. As expected, DPI inhibits the expression at predetermined time points for each of these genes. Taken together, these results suggest that ROS produced by NOXs are involved in radicle and root elongation during rice seed germination, and OsNOX5, 7 and 9 could play crucial roles in rice seed germination. These findings will facilitate further studies of the roles of ROS generated by NOXs during seed germination and seedling establishment and also provide valuable information for the regulation of NOX

  2. Reactive Oxygen Species Generated by NADPH Oxidases Promote Radicle Protrusion and Root Elongation during Rice Seed Germination.

    PubMed

    Li, Wen-Yan; Chen, Bing-Xian; Chen, Zhong-Jian; Gao, Yin-Tao; Chen, Zhuang; Liu, Jun

    2017-01-13

    Seed germination is a complicated biological process that requires regulation through various enzymatic and non-enzymatic mechanisms. Although it has been recognized that reactive oxygen species (ROS) regulate radicle emergence and root elongation in a non-enzymatic manner during dicot seed germination, the role of ROS in monocot seed germination remains unknown. NADPH oxidases (NOXs) are the major ROS producers in plants; however, whether and how NOXs regulate rice seed germination through ROS generation remains unclear. Here, we report that diphenyleneiodinium (DPI), a specific NOX inhibitor, potently inhibited embryo and seedling growth-especially that of the radicle and of root elongation-in a dose-dependent manner. Notably, the DPI-mediated inhibition of radicle and root growth could be eliminated by transferring seedlings from DPI to water. Furthermore, ROS production/accumulation during rice seed germination was quantified via histochemistry. Superoxide radicals (O₂(-)), hydrogen peroxide (H₂O₂) and hydroxyl radicals ((•)OH) accumulated steadily in the coleorhiza, radicle and seedling root of germinating rice seeds. Expression profiles of the nine typical NOX genes were also investigated. According to quantitative PCR, OsNOX5, 7 and 9 were expressed relatively higher. When seeds were incubated in water, OsNOX5 expression progressively increased in the embryo from 12 to 48 h, whereas OsNOX7 and 9 expressions increased from 12 to 24 h and decreased thereafter. As expected, DPI inhibits the expression at predetermined time points for each of these genes. Taken together, these results suggest that ROS produced by NOXs are involved in radicle and root elongation during rice seed germination, and OsNOX5, 7 and 9 could play crucial roles in rice seed germination. These findings will facilitate further studies of the roles of ROS generated by NOXs during seed germination and seedling establishment and also provide valuable information for the regulation of

  3. Lysophosphatidic acid increases the proliferation and migration of adipose‑derived stem cells via the generation of reactive oxygen species.

    PubMed

    Kang, Sangjin; Han, Juhee; Song, Seung Yong; Kim, Won-Serk; Shin, Soyoung; Kim, Ji Hye; Ahn, Hyosun; Jeong, Jin-Hyun; Hwang, Sung-Joo; Sung, Jong-Hyuk

    2015-10-01

    Phospholipid derivatives, such as lysophosphatidic acid (LPA), exhibit mitogenic effects on mesenchymal stem cells; however, the molecular mechanism underlying this stimulation has yet to be identified. The aims of the present study were as follows: To evaluate the stimulatory effects of LPA on the proliferation and migration of adipose‑derived stem cells (ASCs); to study the association between reactive oxygen species (ROS) and LPA signaling in ASCs; and to investigate the microRNAs upregulated by LPA treatment in ASCs. The results of the present study demonstrated that LPA increased the proliferation and migration of ASCs, and acted as a mitogenic signal via extracellular signal‑regulated kinases 1/2 and the phosphoinositide 3‑kinase/Akt signaling pathways. The LPA1 receptor is highly expressed in ASCs, and pharmacological inhibition of it by Ki16425 significantly attenuated the proliferation and migration of ASCs. In addition, LPA treatment generated ROS via NADPH oxidase 4, and ROS were able to function as signaling molecules to increase the proliferation and migration of ASCs. The induction of ROS by LPA treatment also upregulated the expression of miR‑210. A polymerase chain reaction array assay demonstrated that the expression levels of adrenomedullin and Serpine1 were increased following treatment with LPA. Furthermore, transfection with Serpine1‑specific small interfering RNA attenuated the migration of ASCs. In conclusion, the present study is the first, to the best of our knowledge, to report that ROS generation and miR‑210 expression are associated with the LPA‑induced stimulation of ASCs, and that Serpine1 mediates the LPA‑induced migration of ASCs. These results further suggest that LPA may be used for ASC stimulation during stem cell expansion.

  4. TNFα-induced apoptosis enabled by CCN1/CYR61: pathways of reactive oxygen species generation and cytochrome c release.

    PubMed

    Juric, Vladislava; Chen, Chih-Chiun; Lau, Lester F

    2012-01-01

    Although TNFα is a strong inducer of apoptosis, its cytotoxicity in most normal cells in vitro requires blockade of NFκB signaling or inhibition of de novo protein synthesis, typically by the addition of cycloheximide. However, several members of CCN (CYR61/CTGF/NOV) family of extracellular matrix proteins enable TNFα-dependent apoptosis in vitro without inhibiting NFκB or de novo protein synthesis, and CCN1 (CYR61) is essential for optimal TNFα cytotoxicity in vivo. Previous studies showed that CCN1 unmasks the cytotoxicity of TNFα by binding integrins α(v)β(5), α(6)β(1), and the cell surface heparan sulfate proteoglycan syndecan 4 to induce the accumulation of a high level of reactive oxygen species (ROS), leading to a biphasic activation of JNK necessary for apoptosis. Here we show for the first time that CCN1 interacts with the low density lipoprotein receptor-related protein 1 (LRP1) in a protein complex, and that binding to LRP1 is critical for CCN1-induced ROS generation and apoptotic synergism with TNFα. We also found that neutral sphingomyelinase 1 (nSMase1), which contributes to CCN1-induced ROS generation, is required for CCN1/TNFα-induced apoptosis. Furthermore, CCN1 promotes the activation of p53 and p38 MAPK, which mediate enhanced cytochrome c release to amplify the cytotoxicity of TNFα. By contrast, LRP1, nSMase1, p53, and p38 MAPK are not required when TNFα-dependent apoptosis is facilitated by the presence of cycloheximide, indicating that they function in the CCN1 signaling pathway that converges with TNFα-induced signaling events. Since CCN1/CYR61 is a physiological regulator of TNFα cytotoxicity at least in some contexts, these findings may reveal important mediators of TNFα-induced apoptosis in vivo and identify potential therapeutic targets for thwarting TNFα-dependent tissue damage.

  5. Quinones as toxic metabolites of benzene

    SciTech Connect

    Irons, R.D.

    1985-01-01

    Occupational exposure to benzene has long been associated with toxicity to the blood and bone marrow, including lymphocytopenia, pancytopenia, aplastic anemia, acute myelogenous leukemia, and possible lymphoma. A variety of studies have established that benzene itself is not the toxic species but requires metabolism to reactive intermediates. The bioactivation of benzene is complex. Both primary and secondary oxidation of benzene and its metabolites are mediated via cytochrome P-450 in the liver, although the role of secondary metabolism in the bone marrow is not clear. Toxicity is associated with the dihydroxy metabolites, hydroquinone and catechol, which concentrate in bone marrow. Hydroquinone and its terminal oxidation product, p-benzoquinone, have been demonstrated to be potent suppressors of cell growth in culture. Suppression of lymphocyte blastogenesis by these compounds is a sulfhydryl-dependent process and occurs at concentrations that do not result in cell death, or in detectable alterations in energy metabolism, intracellular glutathione concentration, or protein synthesis. Recent studies suggest that these compounds and other membrane-penetrating sulfyhdryl alkylating agents, such as N-ethylmaleimide and cytochalasin A, and endogenous regulatory molecules, such as soluble immune response suppressor (SIRS), interfere with microtubule assembly in vitro and selectively interfere with microtubule-dependent cell functions at identical concentrations. These agents appear to react with nucleophilic sulfhydryl groups essential for guanosine triphosphate binding to tubulin that are particularly sensitive to sulfhydryl-alkylating agents.

  6. Identification of lactate dehydrogenase as a mammalian pyrroloquinoline quinone (PQQ)-binding protein

    PubMed Central

    Akagawa, Mitsugu; Minematsu, Kenji; Shibata, Takahiro; Kondo, Tatsuhiko; Ishii, Takeshi; Uchida, Koji

    2016-01-01

    Pyrroloquinoline quinone (PQQ), a redox-active o-quinone, is an important nutrient involved in numerous physiological and biochemical processes in mammals. Despite such beneficial functions, the underlying molecular mechanisms remain to be established. In the present study, using PQQ-immobilized Sepharose beads as a probe, we examined the presence of protein(s) that are capable of binding PQQ in mouse NIH/3T3 fibroblasts and identified five cellular proteins, including l-lactate dehydrogenase (LDH) A chain, as potential mammalian PQQ-binding proteins. In vitro studies using a purified rabbit muscle LDH show that PQQ inhibits the formation of lactate from pyruvate in the presence of NADH (forward reaction), whereas it enhances the conversion of lactate to pyruvate in the presence of NAD+ (reverse reaction). The molecular mechanism underlying PQQ-mediated regulation of LDH activity is attributed to the oxidation of NADH to NAD+ by PQQ. Indeed, the PQQ-bound LDH oxidizes NADH, generating NAD+, and significantly catalyzes the conversion of lactate to pyruvate. Furthermore, PQQ attenuates cellular lactate release and increases intracellular ATP levels in the NIH/3T3 fibroblasts. Our results suggest that PQQ, modulating LDH activity to facilitate pyruvate formation through its redox-cycling activity, may be involved in the enhanced energy production via mitochondrial TCA cycle and oxidative phosphorylation. PMID:27230956

  7. Identification of lactate dehydrogenase as a mammalian pyrroloquinoline quinone (PQQ)-binding protein.

    PubMed

    Akagawa, Mitsugu; Minematsu, Kenji; Shibata, Takahiro; Kondo, Tatsuhiko; Ishii, Takeshi; Uchida, Koji

    2016-05-27

    Pyrroloquinoline quinone (PQQ), a redox-active o-quinone, is an important nutrient involved in numerous physiological and biochemical processes in mammals. Despite such beneficial functions, the underlying molecular mechanisms remain to be established. In the present study, using PQQ-immobilized Sepharose beads as a probe, we examined the presence of protein(s) that are capable of binding PQQ in mouse NIH/3T3 fibroblasts and identified five cellular proteins, including l-lactate dehydrogenase (LDH) A chain, as potential mammalian PQQ-binding proteins. In vitro studies using a purified rabbit muscle LDH show that PQQ inhibits the formation of lactate from pyruvate in the presence of NADH (forward reaction), whereas it enhances the conversion of lactate to pyruvate in the presence of NAD(+) (reverse reaction). The molecular mechanism underlying PQQ-mediated regulation of LDH activity is attributed to the oxidation of NADH to NAD(+) by PQQ. Indeed, the PQQ-bound LDH oxidizes NADH, generating NAD(+), and significantly catalyzes the conversion of lactate to pyruvate. Furthermore, PQQ attenuates cellular lactate release and increases intracellular ATP levels in the NIH/3T3 fibroblasts. Our results suggest that PQQ, modulating LDH activity to facilitate pyruvate formation through its redox-cycling activity, may be involved in the enhanced energy production via mitochondrial TCA cycle and oxidative phosphorylation.

  8. Uranium Exerts Acute Toxicity by Binding to Pyrroloquinoline Quinone Cofactor

    SciTech Connect

    Michael R. VanEngelen; Robert I. Szilagyi; Robin Gerlach; Brady E. Lee; William A. Apel; Brent M. Peyton

    2011-02-01

    Uranium as an environmental contaminant has been shown to be toxic to eukaryotes and prokaryotes; however, no specific mechanisms of uranium toxicity have been proposed so far. Here a combination of in vivo, in vitro, and in silico studies are presented describing direct inhibition of pyrroloquinoline quinone (PQQ)-dependent growth and metabolism by uranyl cations. Electrospray-ionization mass spectroscopy, UV-vis optical spectroscopy, competitive Ca2+/uranyl binding studies, relevant crystal structures, and molecular modeling unequivocally indicate the preferred binding of uranyl simultaneously to the carboxyl oxygen, pyridine nitrogen, and quinone oxygen of the PQQ molecule. The observed toxicity patterns are consistent with the biotic ligand model of acute metal toxicity. In addition to the environmental implications, this work represents the first proposed molecular mechanism of uranium toxicity in bacteria, and has relevance for uranium toxicity in many living systems.

  9. Two new quinones from the roots of Juglans mandshurica.

    PubMed

    Jin, Mei; Sun, Jinfeng; Li, Ren; Diao, Shengbao; Zhang, Changhao; Cui, Jiongmo; Son, Jong-Keun; Zhou, Wei; Li, Gao

    2016-09-01

    Two new quinones, 1-hydroxy-5-pentyl-anthraquinone (1) and 4-(5-hydroxy-1,4-dioxo-1,4-dihydro-naphthalen-2-ylamino)-butyric acid methyl ester (2), together with two known quinones, 5-hydroxy-2-(2-hydroxy-ethylamino)-(1,4) naphthoquinone (3) and juglone (4) were isolated from the roots of Juglans mandshurica (Juglandaceae). Their structures were elucidated on the basis of spectral data. Compound 3 was isolated from the Juglans genus for the first time. Compounds 1-4 exhibited significant cytotoxicity towards cultured MDA-MB231, HepG2 and SNU638 cells with IC50 values ranging from 4.46 to 88.47 μM.

  10. The Metabolic Fate of ortho-Quinones Derived from Catecholamine Metabolites.

    PubMed

    Ito, Shosuke; Yamanaka, Yuta; Ojika, Makoto; Wakamatsu, Kazumasa

    2016-01-27

    ortho-Quinones are produced in vivo through the oxidation of catecholic substrates by enzymes such as tyrosinase or by transition metal ions. Neuromelanin, a dark pigment present in the substantia nigra and locus coeruleus of the brain, is produced from dopamine (DA) and norepinephrine (NE) via an interaction with cysteine, but it also incorporates their alcoholic and acidic metabolites. In this study we examined the metabolic fate of ortho-quinones derived from the catecholamine metabolites, 3,4-dihydroxyphenylethanol (DOPE), 3,4-dihydroxyphenylethylene glycol (DOPEG), 3,4-dihydroxyphenylacetic acid (DOPAC) and 3,4-dihydroxyphenylmandelic acid (DOMA). The oxidation of catecholic substrates by mushroom tyrosinase was followed by UV-visible spectrophotometry. HPLC analysis after reduction with NaBH₄ or ascorbic acid enabled measurement of the half-lives of ortho-quinones and the identification of their reaction products. Spectrophotometric examination showed that the ortho-quinones initially formed underwent extensive degradation at pH 6.8. HPLC analysis showed that DOPE-quinone and DOPEG-quinone degraded with half-lives of 15 and 30 min at pH 6.8, respectively, and >100 min at pH 5.3. The major product from DOPE-quinone was DOPEG which was produced through the addition of a water molecule to the quinone methide intermediate. DOPEG-quinone yielded a ketone, 2-oxo-DOPE, through the quinone methide intermediate. DOPAC-quinone and DOMA-quinone degraded immediately with decarboxylation of the ortho-quinone intermediates to form 3,4-dihydroxybenzylalcohol (DHBAlc) and 3,4-dihydroxybenzaldehyde (DHBAld), respectively. DHBAlc-quinone was converted to DHBAld with a half-life of 9 min, while DHBAld-quinone degraded rapidly with a half-life of 3 min. This study confirmed the fact that ortho-quinones from DOPE, DOPEG, DOPAC and DOMA are converted to quinone methide tautomers as common intermediates, through proton rearrangement or decarboxylation. The unstable quinone

  11. Plasma effects on the generation of reactive oxygen and nitrogen species in cancer cells in-vitro exposed by atmospheric pressure pulsed plasma jets

    NASA Astrophysics Data System (ADS)

    Kim, Sun Ja; Chung, T. H.

    2015-08-01

    Atmospheric pressure pulsed helium plasma jets are utilized for plasma-cell interactions. The effect of operating parameters such as applied voltage, pulse repetition frequency, and duty ratio on the generation of specific reactive oxygen and nitrogen species in gas and liquid phases and within cells is investigated. The apoptotic changes detected by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling assay in cells caused by plasma exposure are observed to correlate well with the levels of extracellular and intracellular reactive oxygen and nitrogen species.

  12. Chlorophyll-quinone photochemical electron transfer in liposomes

    SciTech Connect

    Hurley, J.K.; Castelli, F.; Tollin, G.

    1981-09-01

    The study described involves the reduction of electron acceptors (quinones) by photoexcited Chloroplasts (Chl). Chl a (from spinach) is incorporated into phosphatidylcholine (either synthetic or from hen egg yolks) liposomes suspended in 10 mM phosphate buffer (pH 7.0). The quinones are either present during liposome formation or added later, depending upon their water solubility. The measurement technique employed is laser flash photolysis. A pulsed nitrogen laser pumps a dye laser, which delivers a short light flash (10 ns) to the sample at a wavelength (655-660 nm) within an absorption band of Chl. This raises Chl to an excited singlet level, which can rapidly cross to the lowest excited triple level (/sup 3/Chl). From this state Chl can transfer an electron to acceptors such as quinones, resulting in the formation of the Chl cation radical (Chl./sup +/) and the semiquinone anion radical (Q./sup +/). Transient absorbance changes ocurring within the sample cell are monitored and can be attributed to processes such as excited state quenching (of /sup 3/Chl by Q) and radical product formation and decay. (JMT)

  13. Phosphate Shifted Oxygen Reduction Pathway on Fe@Fe2O3 Core-Shell Nanowires for Enhanced Reactive Oxygen Species Generation and Aerobic 4-Chlorophenol Degradation.

    PubMed

    Mu, Yi; Ai, Zhihui; Zhang, Lizhi

    2017-07-18

    Phosphate ions widely exist in the environment. Previous studies revealed that the adsorption of phosphate ions on nanoscale zerovalent iron would generate a passivating oxide shell to block reactive sites and thus decrease the direct pollutant reduction reactivity of zerovalent iron. Given that molecular oxygen activation process is different from direct pollutant reduction with nanoscale zerovalent iron, it is still unclear how phosphate ions will affect molecular oxygen activation and reactive oxygen species generation with nanoscale zerovalent iron. In this study, we systematically studied the effect of phosphate ions on molecular oxygen activation with Fe@Fe2O3 nanowires, a special nanoscale zerovalent iron, taking advantages of rotating ring disk electrochemical analysis. It was interesting to find that the oxygen reduction pathway on Fe@Fe2O3 nanowires was gradually shifted from a four-electron reduction pathway to a sequential one-electron reduction one, along with increasing the phosphate ions concentration from 0 to 10 mmol·L(-1). This oxygen reduction pathway change greatly enhanced the molecular oxygen activation and reactive oxygen species generation performances of Fe@Fe2O3 nanowires, and thus increased their aerobic 4-chlorophenol degradation rate by 10 times. These findings shed insight into the possible roles of widely existed phosphate ions in molecular oxygen activation and organic pollutants degradation with nanoscale zerovalent iron.

  14. Quinone Methide Bioactivation Pathway: Contribution to Toxicity and/or Cytoprotection?

    PubMed Central

    Bolton, Judy L.

    2014-01-01

    The formation of quinone methides (QMs) from either direct 2-electron oxidation of 2- or 4-alkylphenols, isomerization of o-quinones, or elimination of a good leaving group could explain the cytotoxic/cytoprotective effects of several drugs, natural products, as well as endogenous compounds. For example, the antiretroviral drug nevirapine and the antidiabetic agent troglitazone both induce idiosyncratic hepatotoxicity through mechanisms involving quinone methide formation. The anesthetic phencyclidine induces psychological side effects potentially through quinone methide mediated covalent modification of crucial macromolecules in the brain. Selective estrogen receptor modulators (SERMs) such as tamoxifen, toremifene, and raloxifene are metabolized to quinone methides which could potentially contribute to endometrial carcinogenic properties and/or induce detoxification enzymes and enhance the chemopreventive effects of these SERMs. Endogenous estrogens and/or estrogens present in estrogen replacement formulations are also metabolized to catechols and further oxidized to o-quinones which can isomerize to quinone methides. Both estrogen quinoids could cause DNA damage which could enhance hormone dependent cancer risk. Natural products such as the food and flavor agent eugenol can be directly oxidized to a quinone methide which may explain the toxic effects of this natural compound. Oral toxicities associated with chewing areca quid could be the result of exposure to hydroxychavicol through initial oxidation to an o-quinone which isomerizes to a p-quinone methide. Similar o-quinone to p-quinone methide isomerization reactions have been reported for the ubiquitous flavonoid quercetin which needs to be taken into consideration when evaluating risk-benefit assessments of these natural products. The resulting reaction of these quinone methides with proteins, DNA, and/or resulting modulation of gene expression may explain the toxic and/or beneficial effects of the parent

  15. Low level laser therapy activates NF-kB via generation of reactive oxygen species in mouse embryonic fibroblasts

    NASA Astrophysics Data System (ADS)

    Chen, Aaron Chih-Hao; Arany, Praveen R.; Huang, Ying-Ying; Tomkinson, Elizabeth M.; Saleem, Taimur; Yull, Fiona E.; Blackwell, Timothy S.; Hamblin, Michael R.

    2009-02-01

    Despite over forty years of investigation on low-level light therapy (LLLT), the fundamental mechanisms underlying photobiomodulation remain unclear. In this study, we isolated murine embryonic fibroblasts (MEF) from transgenic NF-kB luciferase reporter mice and studied their response to 810-nm laser radiation. Significant activation of NFkB was observed for fluences higher than 0.003 J/cm2. NF-kB activation by laser was detectable at 1-hour time point. Moreover, we demonstrated that laser phosphorylated both IKK α/β and NF-kB 15 minutes after irradiation, which implied that laser activates NF-kB via phosphorylation of IKK α/β. Suspecting mitochondria as the source of NF-kB activation signaling pathway, we demonstrated that laser increased both intracellular reactive oxygen species (ROS) by fluorescence microscopy with dichlorodihydrofluorescein and ATP synthesis by luciferase assay. Mitochondrial inhibitors, such as antimycin A, rotenone and paraquat increased ROS and NF-kB activation but had no effect on ATP. The ROS quenchers N-acetyl-L-cysteine and ascorbic acid abrogated laser-induced NF-kB and ROS but not ATP. These results suggested that ROS might play an important role in the signaling pathway of laser induced NF-kB activation. However, the western blot showed that antimycin A, a mitochondrial inhibitor, did not activate NF-kB via serine phosphorylation of IKK α/β as the laser did. On the other hand, LLLT, unlike mitochondrial inhibitors, induced increased cellular ATP levels, which indicates that light also upregulates mitochondrial respiration. ATP upregulation reached a maximum at 0.3 J/cm2 or higher. We conclude that LLLT not only enhances mitochondrial respiration, but also activates the redox-sensitive transcription factor NF-kB by generating ROS as signaling molecules.

  16. The role of water and structure on the generation of reactive oxygen species in peptide/hypericin complexes.

    PubMed

    Souza, Márcia I; Silva, Emerson R; Jaques, Ygor M; Ferreira, Fabio F; Fileti, Eudes E; Alves, Wendel A

    2014-07-01

    Hybrid associates formed between peptide assemblies and fluorophores are attractive mainly because of their unique properties for biomedical applications. Recently, we demonstrated that the production of reactive oxygen species (ROS) by hypericin and their stability in excited states are enhanced upon conjugation with l,l-diphenylalanine microtubes (FF-MNTs). Although the detailed mechanisms responsible for improving the photophysical properties of ROS remain unclear, tentative hypotheses have suggested that the driving force is the growth of overall dipolar moments ascribed either to coupling between aligned H2O dipoles within the ordered structures or to the organization of hypericin molecules on peptide interfaces. To provide new insights on ROS activity in hypericin/FF-MNTs hybrids and further explore the role of water in this respect, we present results obtained from investigations on the behavior of these complexes organized into different crystalline arrangements. Specifically, we monitored and compared the photophysical performance of hypericin bound to FF-MNTs with peptides organized in both hexagonal (water-rich) and orthorhombic (water-free) symmetries. From a theoretical perspective, we present the results of new molecular dynamics simulations that highlight the distinct hypericin/peptide interaction at the interface of FF-MNTs for the different symmetries. As a conclusion, we propose that although water enhances photophysical properties, the organization induced by peptide structures and the availability of a hydrophobic environment surrounding the hypericin/peptide interface are paramount to optimizing ROS generation. The findings presented here provide useful basic research insights for designing peptide/fluorophore complexes with outstanding technological potential. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd.

  17. Dynamics of reactive oxygen species generation in the presence of copper(II)-histidine complex and cysteine.

    PubMed

    Ząbek-Adamska, Anna; Drożdż, Ryszard; Naskalski, Jerzy W

    2013-01-01

    Histidine-copper(II) complex (Cu-His2) is a form of bound copper necessary for cellular copper uptake. Due to the high affinity of histidine to copper(II) ions, the binding of copper(II) by histidine is considered a substantial part of plasma antioxidative defense. Also cysteine plays a role in the antioxidative system. However, we show here that in the presence of oxygen the histidine-copper(II) complex plus cysteine produces reactive oxygen species (ROS). Cysteine concentration was assayed using a thiol specific silver-mercury electrode. Hydrogen peroxide was assayed amperometrically using platinum electrode. ROS formation was followed by chemiluminescence of luminol-fluoresceine-enhanced system. Addition of cysteine to Cu-His2 solution at pH 7.4 in the presence of atmospheric oxygen initiates the synthesis of H2O2 and generation of ROS, which manifests as a burst of chemiluminescence. The reaction has two stages; in the first stage, cysteine is utilized for the synthesis of an unstable intermediary product which becomes a substrate for ROS formation. Anaerobic conditions inhibit ROS formation. Increased cysteine concentration enhances the lag phase of the oxidative burst without influencing the amount of ROS. The synthesis of ROS (measured by chemiluminescence) is proportional to the concentration of Cu-His2 employed. ROS production can be repetitively initiated by further additions of cysteine to the reaction medium. The study suggests that Cu-His2 catalyzes cysteine-dependent reduction of oxygen to superoxide employing an intermediary cysteine-copper(I) complex and enabling Fenton reaction with copper and hydrogen peroxide produced as a secondary product. In effect, Cu-His2 with cysteine may be a source of ROS in biological media.

  18. A photoreducible copper(II)-tren complex of practical value: generation of a highly reactive click catalyst.

    PubMed

    Harmand, Lydie; Lambert, Romain; Scarpantonio, Luca; McClenaghan, Nathan D; Lastécouères, Dominique; Vincent, Jean-Marc

    2013-11-25

    A detailed study on the photoreduction of the copper(II) precatalyst 1 to generate a highly reactive cuprous species for the copper(I)-catalyzed alkyne-azide cycloaddition (CuAAC) click reaction is presented. For the photoactive catalyst described herein, the activation is driven by a photoinduced electron transfer (PET) process harnessing a benzophenone-like ketoprofenate chromophore as a photosensitizer, which is equally the counterion. The solvent is shown to play a major role in the Cu(II) to Cu(I) reduction process as the final electron source, and the influence of the solvent nature on the photoreduction efficiency has been studied. Particular attention was paid to the use of water as a potential solvent, aqueous media being particularly appealing for CuAAC processes. The ability to solubilize the copper-tren complexes in water through the formation of inclusion complexes with β-CDs is demonstrated. Data is also provided on the fate of the copper(I)-tren catalytic species when reacting with O2, O2 being used to switch off the catalysis. These data show that partial oxidation of the secondary benzylamine groups of the ligand to benzylimines occurs. Preliminary results show that when prolonged irradiation times are employed a Cu(I) to Cu(0) over-reduction process takes place, leading to the formation of copper nanoparticles (NPs). Finally, the main objective of this work being the development of photoactivable catalysts of practical value for the CuAAC, the catalytic, photolatent, and recycling properties of 1 in water and organic solvents are reported.

  19. 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.

  20. Humic acid effect on catalase activity and the generation of reactive oxygen species in corn (Zea mays).

    PubMed

    Cordeiro, Flávio Couto; Santa-Catarina, Claudete; Silveira, Vanildo; de Souza, Sonia Regina

    2011-01-01

    Humic acids (HAs) have positive effects on plant physiology, but the molecular mechanisms underlying these events are only partially understood. The induction of root growth and emission of lateral roots (LRs) promoted by exogenous auxin is a natural phenomenon. Exogenous auxins are also associated with HA. Gas nitric oxide (NO) is a secondary messenger produced endogenously in plants. It is associated with metabolic events dependent on auxin. With the application of auxin, NO production is significantly increased, resulting in positive effects on plant physiology. Thus it is possible to evaluate the beneficial effects of the application of HA as an effect of auxin. To investigate the effects of HA the parameters of root growth, Zea mays was studied by evaluating the application of 3 mM C L⁻¹ of HA extracted from Oxisol and 100 µM SNP (sodium nitroprusside) and the NO donor, subject to two N-NO₃⁻, high dose (5.0 mM N-NO₃⁻) and low dose (5.0 mM N-NO₃⁻). Treatments with HA and NO were positively increased, regardless of the N-NO₃⁻ taken, as assessed by fresh weight and dry root, issue of LRs. The effects were more pronounced in the treatment with a lower dose of N-NO₃⁻. Detection of reactive oxygen species (ROS) in vivo and catalase activity were evaluated; these tests were associated with root growth. Under application of the bioactive substances tested, detection of ROS and catalase activity increased, especially in treatments with lower doses of N-NO₃⁻. The results of this experiment indicate that the effects of HA are dependent on ROS generation, which act as a messenger that induces root growth and the emission of LRs.

  1. Membrane lipid defects are responsible for the generation of reactive oxygen species in peripheral blood mononuclear cells from vitiligo patients.

    PubMed

    Dell'Anna, Maria Lucia; Ottaviani, Monica; Bellei, Barbara; Albanesi, Veronica; Cossarizza, Andrea; Rossi, Luisa; Picardo, Mauro

    2010-04-01

    The pathogenesis of vitiligo, an acquired depigmenting disease of the skin, involves oxidative stress. Based on that, the generation of reactive oxygen species (ROS) by the mitochondria may be relevant in the pathogenesis of vitiligo. Here, we evaluate the biochemical and functional alterations involved in the defective activity that has been previously described both in melanocytes and peripheral blood mononuclear cells (PBMC) from vitiligo patients. Moreover, we used a freeze-thaw test as a mild stress stimulus to disclose any latent defects in the assembly of membrane lipids that may compromise the functionality of the membrane itself. We show that the lipid constitution of the membrane is altered in vitiligo. Specifically, the cardiolipin (CL) level in the mitochondrial inner membrane is reduced and the level of cholesterol is increased. Furthermore, an increase in the expression level of 3-hydroxy-3methyl-glutaryl-CoenzymeA-reductase (HMG-CoA reductase), the rate-limiting enzyme for cholesterol biosynthesis, was also seen. Associated with that, the expression of electron transport chain (ETC) lipid-dependent subunits was also modified, and their expression was further affected by the freeze-thaw stress. The expression of CL-independent mitochondrial proteins, such as porin and Bcl2, were unaffected in vitiligo PBMC. These data confirm that ETC protein expression mainly correlates with lipid arrangement and that loss of their expression is not due to generalized or random oxidative-mediated damage. We suggest that the modification of membrane lipid components in vitiligo cells may be the biochemical basis for the mitochondrial impairment and the subsequent production of intracellular ROS following the exposure to a mild stress. J. Cell. Physiol. 223: 187-193, 2010. (c) 2009 Wiley-Liss, Inc.

  2. UNCOUPLING PROTEIN DOWNREGULATION IN DOXORUBICIN INDUCED HEART FAILURE IMPROVES MITOCHONDRIAL COUPLING BUT INCREASES REACTIVE OXYGEN SPECIES GENERATION

    PubMed Central

    Bugger, Heiko; Guzman, Cinthia; Zechner, Christoph; Palmeri, Monica; Russell, Kerry S.; Russell, Raymond R.

    2010-01-01

    PURPOSE Doxorubicin-based chemotherapy is limited by the development of dose-dependent left ventricular dysfunction and congestive heart failure caused by reactive oxygen species (ROS). Uncoupling proteins (UCP) can inhibit mitochondrial ROS production as well as decrease myocyte damage from exogenous ROS. Prior studies have shown that cardiac UCP2 and UCP3 mRNA expression is decreased with acute doxorubicin treatment. However, the expression of UCP protein in hearts with doxorubicin cardiotoxicity and the resultant changes in mitochondrial function and oxidant stress have not been determined. METHODS Heart failure was induced in Sprague-Dawley rats with intraperitoneal injections of doxorubicin (2 mg/kg t.i.w., total dose: 18 mg/kg). Mitochondria were isolated from mice receiving doxorubicin or saline injections for determination of UCP2 and UCP3 expression. In addition, mitochondrial respiration, ATP synthesis and ROS production were determined. RESULTS Doxorubicin-induced heart failure was associated with significant decreases in UCP2 and UCP3 protein expression compared to nonfailing hearts (p<0.05). While the rates of state 3 and state 4 respiration and ATP synthesis were lower in mitochondria isolated from failing hearts, the respiratory control ratio was 15% higher (p<0.05) and the ratio of ATP production to oxygen consumption was 25% higher (p<0.05) in mitochondria from failing hearts, indicating greater coupling between citric acid cycle flux and mitochondrial ATP synthesis. However, the decrease in UCP expression was associated with 50% greater mitochondrial ROS generation (p<0.05). CONCLUSIONS Downregulation of myocardial UCP2 and UCP3 in the setting of doxorubicin-induced heart failure is associated with improved efficiency of ATP synthesis, which might compensate for abnormal energy metabolism. However, this beneficial effect is counterbalanced by greater oxidant stress. PMID:20809120

  3. 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.

  4. Reactive oxygen species generated in chloroplasts contribute to tobacco leaf infection by the necrotrophic fungus Botrytis cinerea.

    PubMed

    Rossi, Franco R; Krapp, Adriana R; Bisaro, Fabiana; Maiale, Santiago J; Pieckenstain, Fernando L; Carrillo, Néstor

    2017-09-14

    Reactive oxygen species (ROS) play fundamental roles in plant responses to pathogen infection, including modulation of cell death processes and defense-related gene expression. Cell death triggered as part of the hypersensitive response enhances resistance to biotrophic pathogens, but favors virulence of necrotrophs. Even though the involvement of ROS in the orchestration of defense responses is well established, the relative contribution of specific subcellular ROS sources to plant resistance against microorganisms with different pathogenesis strategies is not completely known. The aim of this work was to investigate the role of chloroplastic ROS in plant defense against a typical necrotrophic fungus, Botrytis cinerea. For this purpose, we used transgenic tobacco lines expressing a plastid-targeted cyanobacterial flavodoxin (pfld lines), which accumulate lower chloroplastic ROS in response to different stresses. Tissue damage and fungal growth were significantly reduced in infected leaves of pfld plants, as compared to infected wild-type (WT) counterparts. ROS build-up triggered by Botrytis infection and associated to chloroplasts was significantly decreased (70-80%) in pfld leaves relative to the wild type. Phytoalexin accumulation and expression of pathogenesis-related genes were induced to a lower degree in pfld plants than in WT siblings. The impact of fungal infection on photosynthetic activity was also lower in pfld leaves. The results indicate that chloroplast-generated ROS play a major role in lesion development during Botrytis infection. This work demonstrates that the modulation of chloroplastic ROS levels by expression of a heterologous antioxidant protein can provide a significant degree of protection against a canonical necrotrophic fungus. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  5. Premature senescence in human breast cancer and colon cancer cells by tamoxifen-mediated reactive oxygen species generation.

    PubMed

    Lee, Young-Hoon; Kang, Beom Sik; Bae, Young-Seuk

    2014-03-03

    Cellular senescence is an important tumor suppression process in vivo. Tamoxifen is a well-known anti-breast cancer drug; however, its molecular function is poorly understood. Here, we examined whether tamoxifen promotes senescence in breast cancer and colon cancer cells for the first time. Human breast cancer MCF-7, T47D, and MDA-MB-435 and colorectal cancer HCT116 cells were treated with tamoxifen. Cellular senescence was measured by SA-β-gal staining and based on the protein expression of p53 and p21(Cip1/WAF1). The production of reactive oxygen species (ROS) was determined by staining with CM-H2DCFDA and dihydroethidium (DHE). CK2 activity was assessed with a specific peptide substrate. Tamoxifen promoted senescence phenotype and ROS generation in MCF-7 and HCT116 cells. The ROS scavenger, N-acetyl-l-cysteine (NAC), and the NADPH oxidase inhibitor, apocynin, almost completely abolished this event. Tamoxifen inhibited the catalytic activity of CK2. Overexpression of CK2α antagonized senescence mediated by tamoxifen, indicating that tamoxifen induced senescence via a CK2-dependent pathway. A well-known CK2 inhibitor, 5,6-dichloro-1-β-d-ribofuranosylbenzimidazole (DRB), also stimulated ROS production and senescence in MCF-7 cells. Finally, experiments using T47D (wild-type p53) and MDA-MB-435 (mutant p53) cell lines suggested that tamoxifen induces p53-independent ROS production as well as p53-dependent senescence in breast cancer cells. These results demonstrate that tamoxifen promotes senescence through a ROS-p53-p21(Cip1/WAF1) dependent pathway by inhibiting CK2 activity in breast cancer and colon cancer cells. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Photochemical formation and chemistry of long-lived adamantylidene-quinone methides and 2-adamantyl cations.

    PubMed

    Basarić, Nikola; Zabcić, Ivana; Mlinarić-Majerski, Kata; Wan, Peter

    2010-01-01

    Hydroxymethylphenols strategically substituted with the 2-hydroxy-2-adamantyl moiety, AdPh 8-10, were synthesized, and their photochemical reactivity was investigated. On excitation to the singlet excited state, AdPh 8 undergoes intramolecular proton transfer coupled with a loss of H(2)O giving quinone methide 8QM. The presence of 8QM has been detected by laser flash photolysis (CH(3)CN-H(2)O 1:1, tau = 0.55 s) and UV-vis spectroscopy. Singlet excited states of AdPh 9 and 10 in the presence of H(2)O dehydrate giving 9QM and 10QM. Photochemically formed QMs are trapped by nucleophiles giving the addition products (e.g., Phi for methanolysis of 8 is 0.55). In addition, the zwitterionic 9QM undergoes an unexpected rearrangement involving transformation of the 2-phenyl-2-adamantyl cation into the 4-phenyl-2-adamantyl cation (Phi approximately 0.03). An analogous rearrangement was observed with methoxy derivatives 9a and 10a. Zwitterionic 9QM was characterized by LFP in 2,2,2-trifluoroethanol (tau = 1 mus). In TFE, in the ground state, AdPh 10 is in equilibrium with 10QM, which allowed for recording the (1)H and (13)C NMR spectra of the QM. Introduction of the adamantyl substituent into the o-hydroxymethylphenol moiety increased the quantum yield of the associated QM formation by up to 3-fold and significantly prolonged their lifetimes. Furthermore, adamantyl substituent made the study of the alkyl-substituted quinone methides easier by LFP by prolonging their lifetimes and increasing the quantum yields of formation.

  7. Enhanced dechlorination of carbon tetrachloride by Geobacter sulfurreducens in the presence of naturally occurring quinones and ferrihydrite.

    PubMed

    Doong, Ruey-an; Lee, Chun-chi; Lien, Chia-min

    2014-02-01

    The effect of naturally occurring quinones including lawsone (LQ), ubiquinone (UQ), juglone (JQ), and 1,4-naphthoquinone (NQ) on the biotransformation of carbon tetrachloride (CT) in the presence of Geobacter sulfurreducens and ferrihydrite was investigated. AQDS was used as the model compound for comparison. The reductive dissolution of ferrihydrite by G. sulfurreducens was enhanced by AQDS, NQ, and LQ. However, addition of UQ and JQ had little enhancement effect on Fe(II) production. The bioreduction efficiency and rate of ferrihydrite was highly dependent on the natural property and concentration of quinone compounds and the addition of low concentrations of LQ and NQ significantly accelerated the biotransformation rate of CT. The pseudo-first-order rate constants for CT dechlorination (kobsCT) in AQDS-, LQ- and NQ-amended batches were 5.4-5.8, 4.6-7.4 and 2.4-5.8 times, respectively, higher than those in the absence of quinone. A good relationship between kobsCT for CT dechlorination and bioreduction ratio of ferrihydrite was observed, indicating the important role of biogenic Fe(II) in dechlorination of CT under iron-reducing conditions. Spectroscopic analysis showed that AQDS and NQ could be reduced to semiquinones and hydroquinones, while only hydroquinones were generated in LQ-amended batches.

  8. NADH-quinone oxidoreductase: PSST subunit couples electron transfer from iron–sulfur cluster N2 to quinone

    PubMed Central

    Schuler, Franz; Yano, Takahiro; Di Bernardo, Salvatore; Yagi, Takao; Yankovskaya, Victoria; Singer, Thomas P.; Casida, John E.

    1999-01-01

    The proton-translocating NADH-quinone oxidoreductase (EC 1.6.99.3) is the largest and least understood enzyme complex of the respiratory chain. The mammalian mitochondrial enzyme (also called complex I) contains more than 40 subunits, whereas its structurally simpler bacterial counterpart (NDH-1) in Paracoccus denitrificans and Thermus thermophilus HB-8 consists of 14 subunits. A major unsolved question is the location and mechanism of the terminal electron transfer step from iron–sulfur cluster N2 to quinone. Potent inhibitors acting at this key region are candidate photoaffinity probes to dissect NADH-quinone oxidoreductases. Complex I and NDH-1 are very sensitive to inhibition by a variety of structurally diverse toxicants, including rotenone, piericidin A, bullatacin, and pyridaben. We designed (trifluoromethyl)diazirinyl[3H]pyridaben ([3H]TDP) as our photoaffinity ligand because it combines outstanding inhibitor potency, a suitable photoreactive group, and tritium at high specific activity. Photoaffinity labeling of mitochondrial electron transport particles was specific and saturable. Isolation, protein sequencing, and immunoprecipitation identified the high-affinity specifically labeled 23-kDa subunit as PSST of complex I. Immunoprecipitation of labeled membranes of P. denitrificans and T. thermophilus established photoaffinity labeling of the equivalent bacterial NQO6. Competitive binding and enzyme inhibition studies showed that photoaffinity labeling of the specific high-affinity binding site of PSST is exceptionally sensitive to each of the high-potency inhibitors mentioned above. These findings establish that the homologous PSST of mitochondria and NQO6 of bacteria have a conserved inhibitor-binding site and that this subunit plays a key role in electron transfer by functionally coupling iron–sulfur cluster N2 to quinone. PMID:10097178

  9. Sequential reduction of mitochondrial transmembrane potential and generation of reactive oxygen species in early programmed cell death

    PubMed Central

    1995-01-01

    Programmed cell death (PCD) is a physiological process commonly defined by alterations in nuclear morphology (apoptosis) and/or characteristic stepwise degradation of chromosomal DNA occurring before cytolysis. However, determined characteristics of PCD such as loss in mitochondrial reductase activity or cytolysis can be induced in enucleated cells, indicating cytoplasmic PCD control. Here we report a sequential disregulation of mitochondrial function that precedes cell shrinkage and nuclear fragmentation. A first cyclosporin A-inhibitable step of ongoing PCD is characterized by a reduction of mitochondrial transmembrane potential, as determined by specific fluorochromes (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbocyanine++ + iodide; 3,3'dihexyloxacarbocyanine iodide). Cytofluorometrically purified cells with reduced mitochondrial transmembrane potential are initially incapable of oxidizing hydroethidine (HE) into ethidium. Upon short-term in vitro culture, such cells acquire the capacity of HE oxidation, thus revealing a second step of PCD marked by mitochondrial generation of reactive oxygen species (ROS). This step can be selectively inhibited by rotenone and ruthenium red yet is not affected by cyclosporin A. Finally, cells reduce their volume, a step that is delayed by radical scavengers, indicating the implication of ROS in the apoptotic process. This sequence of alterations accompanying early PCD is found in very different models of apoptosis induction: glucocorticoid-induced death of lymphocytes, activation-induced PCD of T cell hybridomas, and tumor necrosis factor-induced death of U937 cells. Transfection with the antiapoptotic protooncogene Bcl-2 simultaneously inhibits mitochondrial alterations and apoptotic cell death triggered by steroids or ceramide. In vivo injection of fluorochromes such as 5,5',6,6'-tetrachloro-1,1',3,3'- tetraethylbenzimidazolcarbocyanine iodide; 3,3'dihexyloxacarbocyanine iodide; or HE allows for the detection of

  10. Silver nanoparticles synthesized from Adenium obesum leaf extract induced DNA damage, apoptosis and autophagy via generation of reactive oxygen species.

    PubMed

    Farah, Mohammad Abul; Ali, Mohammad Ajmal; Chen, Shen-Ming; Li, Ying; Al-Hemaid, Fahad Mohammad; Abou-Tarboush, Faisal Mohammad; Al-Anazi, Khalid Mashay; Lee, Joongku

    2016-05-01

    Silver nanoparticles (AgNPs) are an important class of nanomaterial used for a wide range of industrial and biomedical applications. Adenium obesum is a plant of the family Apocynaceae that is rich in toxic cardiac glycosides; however, there is scarce information on the anticancer potential of its AgNPs. We herein report the novel biosynthesis of AgNPs using aqueous leaf extract of A. obesum (AOAgNPs). The synthesis of AOAgNPs was monitored by color change and ultraviolet-visible spectroscopy (425 nm). It was further characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The FTIR spectra for the AOAgNPs indicated the presence of terpenoids, long chain fatty acids, secondary amide derivatives and proteins that could be responsible for the reduction and capping of the formed AOAgNPs. X-ray diffraction confirmed the crystallinity of the AgNPs. The TEM images revealed mostly spherical particles in the size range of 10-30 nm. The biological properties of novel AOAgNPs were investigated on MCF-7 breast cancer cells. Cell viability was determined by the MTT assay. Generation of reactive oxygen species (ROS), DNA damage, induction of apoptosis and autophagy were assessed. A dose-dependent decrease in the cell viability was observed. The IC50 value was calculated as 217 μg/ml. Both qualitative and quantitative evaluation confirmed about a 2.5 fold increase in the generation of ROS at the highest concentration of 150 μg/ml. A significant (p<0.05) increase in the DNA damage evaluated by comet assay was evident. Flow cytometry revealed an increase in the apoptotic cells (24%) in the AOAgNPs treated group compared to the control. Acridine orange staining of acidic vesicles in exposed cells confirmed the induction of autophagy. These findings suggest that AOAgNPs increased the level of ROS resulting in heightened the DNA damage, apoptosis and autophagy in MCF-7 cells.

  11. Phototoxicity of nano titanium dioxides in HaCaT keratinocytes—Generation of reactive oxygen species and cell damage

    SciTech Connect

    Yin, Jun-Jie; Liu, Jun; Ehrenshaft, Marilyn; Roberts, Joan E.; Fu, Peter P.; Mason, Ronald P.; Zhao, Baozhong

    2012-08-15

    Nano-sized titanium dioxide (TiO{sub 2}) is among the top five widely used nanomaterials for various applications. In this study, we determine the phototoxicity of TiO{sub 2} nanoparticles (nano-TiO{sub 2}) with different molecular sizes and crystal forms (anatase and rutile) in human skin keratinocytes under UVA irradiation. Our results show that all nano-TiO{sub 2} particles caused phototoxicity, as determined by the MTS assay and by cell membrane damage measured by the lactate dehydrogenase (LDH) assay, both of which were UVA dose- and nano-TiO{sub 2} dose-dependent. The smaller the particle size of the nano-TiO{sub 2} the higher the cell damage. The rutile form of nano-TiO{sub 2} showed less phototoxicity than anatase nano-TiO{sub 2}. The level of photocytotoxicity and cell membrane damage is mainly dependent on the level of reactive oxygen species (ROS) production. Using polyunsaturated lipids in plasma membranes and human serum albumin as model targets, and employing electron spin resonance (ESR) oximetry and immuno-spin trapping as unique probing methods, we demonstrated that UVA irradiation of nano-TiO{sub 2} can induce significant cell damage, mediated by lipid and protein peroxidation. These overall results suggest that nano-TiO{sub 2} is phototoxic to human skin keratinocytes, and that this phototoxicity is mediated by ROS generated during UVA irradiation. Highlights: ► We evaluate the phototoxicity of nano-TiO{sub 2} with different sizes and crystal forms. ► The smaller the particle size of the nano-TiO{sub 2} the higher the cell damage. ► The rutile form of nano-TiO{sub 2} showed less phototoxicity than anatase nano-TiO{sub 2}. ► ESR oximetry and immuno-spin trapping techniques confirm UVA-induced cell damage. ► Phototoxicity is mediated by ROS generated during UVA irradiation of nano-TiO{sub 2}.

  12. Program for certification of waste from contained firing facility: Establishment of waste as non-reactive and discussion of potential waste generation problems

    SciTech Connect

    Green, L.; Garza, R.; Maienschein, J.; Pruneda, C.

    1997-09-30

    Debris from explosives testing in a shot tank that contains 4 weight percent or less of explosive is shown to be non-reactive under the specified testing protocol in the Code of Federal Regulations. This debris can then be regarded as a non-hazardous waste on the basis of reactivity, when collected and packaged in a specified manner. If it is contaminated with radioactive components (e.g. depleted uranium), it can therefore be disposed of as radioactive waste or mixed waste, as appropriate (note that debris may contain other materials that render it hazardous, such as beryllium). We also discuss potential waste generation issues in contained firing operations that are applicable to the planned new Contained Firing Facility (CFF). The goal of this program is to develop and document conditions under which shot debris from the planned Contained Firing Facility (CFF) can be handled, shipped, and accepted for waste disposal as non-reactive radioactive or mixed waste. This report fulfills the following requirements as established at the outset of the program: 1. Establish through testing the maximum level of explosive that can be in a waste and still have it certified as non-reactive. 2. Develop the procedure to confirm the acceptability of radioactive-contaminated debris as non-reactive waste at radioactive waste disposal sites. 3. Outline potential disposal protocols for different CFF scenarios (e.g. misfires with scattered explosive).

  13. Hydrolysis of the quinone methide of butylated hydroxytoluene in aqueous solutions.

    PubMed

    Willcockson, Maren Gulsrud; Toteva, Maria M; Stella, Valentino J

    2013-10-01

    Butylated hydroxytoluene or BHT is an antioxidant commonly used in pharmaceutical formulations. BHT upon oxidation forms a quinone methide (QM). QM is a highly reactive electrophilic species that can undergo nucleophilic addition. Here, the kinetic reactivity of QM with water at various apparent pH values in a 50% (v/v) water-acetonitrile solution at constant ionic strength of I = 0.5 (NaCl)4 , was studied. The hydrolysis of QM in the presence of added acid, base, sodium chloride, and phosphate buffer resulted in the formation of only one product--the corresponding 3,5-di-tert-butyl-4-hydroxybenzyl alcohol (BA). The rate of BA formation was catalyzed by the addition of acid and base, but not chloride and phosphate species. Nucleophilic excipients, used in the pharmaceutical formulation, or nucleophilic groups on active pharmaceutical ingredient molecule may form adducts with QM, the immediate oxidative product of BHT degradation, thus having implications for drug product impurity profiles. Because of these considerations, BHT should be used with caution in formulations containing drugs or excipients capable of acting as nucleophiles. © 2013 Wiley Periodicals, Inc. and the American Pharmacists Association.

  14. Design and Synthesis of Novel Isoxazole Tethered Quinone-Amino Acid Hybrids

    PubMed Central

    Ravi Kumar, P.; Sambaiah, M.; Kandula, Venu; Payili, Nagaraju; Jaya Shree, A.; Yennam, Satyanarayana

    2014-01-01

    A new series of isoxazole tethered quinone-amino acid hybrids has been designed and synthesized involving 1,3-dipolar cycloaddition reaction followed by an oxidation reaction using cerium ammonium nitrate (CAN). Using this method, for the first time various isoxazole tethered quinone-phenyl alanine and quinone-alanine hybrids were synthesized from simple commercially available 4-bromobenzyl bromide, propargyl bromide, and 2,5-dimethoxybenzaldehyde in good yield. PMID:25709839

  15. Application of simultaneous active and reactive power modulation of superconducting magnetic energy storage unit to damp turbine-generator subsynchronous oscillations

    SciTech Connect

    Wu, Chijui; Lee, Yuangshung )

    1993-03-01

    An active and reactive power (P-Q) simultaneous control scheme which is based on a superconducting magnetic energy storage (SMES) unit is designed to damp out the subsynchronous resonant (SSR) oscillations of a turbine-generator unit. In order to suppress unstable torsional mode oscillations, a proportional-integral-derivative (PID) controller is employed to modulate the active and reactive power input/output of the SMES unit according to speed deviation of the generator shaft. The gains of the proposed PID controller are determined by pole assignment approach based on modal control theory. Eigenvalue analysis of the studied system shows that the PID controller is quite effective over a wide range of operating conditions. Dynamic simulations using the nonlinear system model are also performed to demonstrate the damping effect of the proposed control scheme under disturbance conditions.

  16. Evidence for the formation of a quinone methide during the oxidation of the insect cuticular sclerotizing precursor 1,2-dehydro-N-acetyldopamine.

    PubMed

    Sugumaran, M; Semensi, V; Kalyanaraman, B; Bruce, J M; Land, E J

    1992-05-25

    1,2-Dehydro-N-acetyldopamine (dehydro-NADA) is an important catecholamine derivative involved in the cross-linking of insect cuticular components during sclerotization. Since sclerotization is a vital process for the survival of insects, and is closely related to melanogenesis, it is of interest to unravel the chemical mechanisms participating in this process. The present paper reports on the mechanism by which dehydro-NADA is oxidatively activated to form reactive intermediate(s) as revealed by pulse radiolysis, electron spin resonance spectroscopy, high performance liquid chromatography, and ultraviolet-visible spectroscopic analysis. Pulse radiolytic one-electron oxidation of dehydro-NADA by N3. (k = 5.3 x 10(9) M-1 s-1) or Br2.- (k = 7.5 x 10(8) M-1 s-1) at pH6 resulted in the rapid generation of the corresponding semiquinone radical, lambda max 400 nm, epsilon = 20,700 M-1 cm-1. This semiquinone decayed to form a second transient intermediate, lambda max 485 nm, epsilon = 8000 M-1 cm-1, via a second order disproportionation process, k = 6.2 x 10(8) M-1 s-1. At pH 6 in the presence of azide, the first order decay of this second intermediate occurred over milliseconds; the rate decreases at higher pH. At pH 6 in the presence of bromide, the intermediate decayed much more slowly over seconds, k = 0.15 s-1. Under such conditions, the dependence of the first order decay constant upon parent dehydro-NADA concentration led to a second order rate constant of 8.5 x 10(2) M-1 s-1 for reaction of the intermediate with the parent, probably to form benzodioxan "dimers." (The term dimer is used for convenience; the products are strictly bisdehydrodimers of dehydro-NADA (see "Discussion" and Fig. 11)) Rate constants of 5.9 x 10(5), 4.5 x 10(5), 2.8 x 10(4) and 3.5 x 10(4) M-1 s-1 were also obtained for decay of the second intermediate in the presence of cysteine, cysteamine, o-phenylenediamine, and p-aminophenol, respectively. By comparison with the UV-visible spectroscopic

  17. Compositions comprising a polypeptide having cellulolytic enhancing activity and a quinone compound and uses thereof

    DOEpatents

    Quinlan, Jason; Xu, Feng; Sweeney, Matthew

    2016-03-01

    The present invention relates to compositions comprising: a polypeptide having cellulolytic enhancing activity and a quinone compound. The present invention also relates to methods of using the compositions.

  18. Catalytic asymmetric diels-alder reaction of quinone imine ketals: a site-divergent approach.

    PubMed

    Hashimoto, Takuya; Nakatsu, Hiroki; Maruoka, Keiji

    2015-04-07

    The catalytic asymmetric Diels-Alder reaction of quinone imine ketals with diene carbamates catalyzed by axially chiral dicarboxylic acids is reported herein. A variety of primary and secondary alkyl-substituted quinone derivatives which have not been applied in previous asymmetric quinone Diels-Alder reactions could be employed using this method. More importantly, we succeeded in developing a strategy to divert the reaction site in unsymmetrical 3-alkyl quinone imine ketals from the inherently favored unsubstituted C=C bond to the disfavored alkyl-substituted C=C bond. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Sum-Frequency Generation Spectroscopy for Studying Organic Layers at Water-Air Interfaces: Microlayer Monitoring and Surface Reactivity

    NASA Astrophysics Data System (ADS)

    Laß, Kristian; Kleber, Joscha; Bange, Hermann; Friedrichs, Gernot

    2015-04-01

    The sea surface microlayer, according to commonly accepted terminology, comprises the topmost millimetre of the oceanic water column. It is often enriched with organic matter and is directly influenced by sunlight exposure and gas exchange with the atmosphere, hence making it a place for active biochemistry and photochemistry as well as for heterogeneous reactions. In addition, surface active material either is formed or accumulates directly at the air-water interface and gives rise to very thin layers, sometimes down to monomolecular thickness. This "sea surface nanolayer" determines the viscoelastic properties of the seawater surface and thus may impact the turbulent air-sea gas exchange rates. To this effect, this small scale layer presumably plays an important role for large scale changes of atmospheric trace gas concentrations (e.g., by modulating the ocean carbon sink characteristics) with possible implications for coupled climate models. To date, detailed knowledge about the composition, structure, and reactivity of the sea surface nanolayer is still scarce. Due to its small vertical dimension and the small amount of material, this surfactant layer is very difficult to separate and analyse. A way out is the application of second-order nonlinear optical methods, which make a direct surface-specific and background-free detection of this interfacial layer possible. In recent years, we have introduced the use of vibrational sum frequency generation (VSFG) spectroscopy to gain insight into natural and artificial organic monolayers at the air-water interface. In this contribution, the application of VSFG spectroscopy for the analysis of the sea surface nanolayer will be illustrated. Resulting spectra are interpreted in terms of layer composition and surfactant classes, in particular with respect to carbohydrate-containing molecules such as glycolipids. The partitioning of the detected surfactants into soluble and non-soluble ("wet" and "dry") surfactants will be

  20. Type-II NADH:quinone oxidoreductase from Staphylococcus aureus has two distinct binding sites and is rate limited by quinone reduction.

    PubMed

    Sena, Filipa V; Batista, Ana P; Catarino, Teresa; Brito, José A; Archer, Margarida; Viertler, Martin; Madl, Tobias; Cabrita, Eurico J; Pereira, Manuela M

    2015-10-01

    A prerequisite for any rational drug design strategy is understanding the mode of protein-ligand interaction. This motivated us to explore protein-substrate interaction in Type-II NADH:quinone oxidoreductase (NDH-2) from Staphylococcus aureus, a worldwide problem in clinical medicine due to its multiple drug resistant forms. NDHs-2 are involved in respiratory chains and recognized as suitable targets for novel antimicrobial therapies, as these are the only enzymes with NADH:quinone oxidoreductase activity expressed in many pathogenic organisms. We obtained crystal and solution structures of NDH-2 from S. aureus, showing that it is a dimer in solution. We report fast kinetic analyses of the protein and detected a charge-transfer complex formed between NAD(+) and the reduced flavin, which is dissociated by the quinone. We observed that the quinone reduction is the rate limiting step and also the only half-reaction affected by the presence of HQNO, an inhibitor. We analyzed protein-substrate interactions by fluorescence and STD-NMR spectroscopies, which indicate that NADH and the quinone bind to different sites. In summary, our combined results show the presence of distinct binding sites for the two substrates, identified quinone reduction as the rate limiting step and indicate the establishment of a NAD(+)-protein complex, which is released by the quinone.

  1. Photoinduced reduction of divalent mercury by quinones in the presence of formic acid under anaerobic conditions.

    PubMed

    Berkovic, Andrea M; Bertolotti, Sonia G; Villata, Laura S; Gonzalez, Mónica C; Pis Diez, Reinaldo; Mártire, Daniel O

    2012-11-01

    The laser flash photolysis technique (λ(exc)=355 nm) was used to investigate the mechanism of the HgCl(2) reduction mediated by CO(2)(-) radicals generated from quenching of the triplet states of 1,4-naphthoquinone (NQ) by formic acid. Kinetic simulations of the experimental signals support the proposed reaction mechanism. This system is of potential interest in the development of UV-A photoinduced photolytic procedures for the treatment of Hg(II) contaminated waters. The successful replacement of NQ with a commercial fulvic acid, as a model compound of dissolved organic matter, showed that the method is applicable to organic matter-containing waters without the addition of quinones.

  2. Reactions of oxygen radicals with the quinone ring of coenzyme Q.

    PubMed

    Fiorentini, D; Cabrini, L; Sechi, A M; Landi, L

    1991-01-01

    Coenzyme Q, besides its role in electron transfer reactions, may act as a radical scavenger. The effect of oxygen radicals produced by ultrasonic irradiation on the quinone ring was investigated. Aqueous solutions of a Q homologue, completely lacking the side chain, were irradiated and the modifications were spectrophotometrically followed. The experimental results show that both degradation and reduction of the benzoquinone ring took place when the irradiation was performed in water. Data obtained when ultrasonic irradiation was carried out in the presence of OH. scavengers, as formate, organic and inorganic buffers, suggest: a) the responsible species for most the ubiquinol generated by sonication appeared to be the superoxide radical b) addition reactions of OH. radicals with the aromatic ring led probably to the degradation of Coenzyme Q molecules.

  3. Formation of long-lived reactive species of blood serum proteins induced by low-intensity irradiation of helium-neon laser and their involvement in the generation of reactive oxygen species.

    PubMed

    Ivanov, Vladimir E; Usacheva, Anna M; Chernikov, Anatoly V; Bruskov, Vadim I; Gudkov, Sergey V

    2017-09-14

    It was demonstrated that low-intensity radiation of helium-neon (He-Ne) laser at 632.8nm, which leads to the transition of oxygen to a singlet state, causes the formation of reactive oxygen species (ROS) - hydrogen peroxide, hydroxyl and superoxide (hydroperoxide) radicals - in aqueous solutions. The oxygen effect - dependence of hydrogen peroxide formation on the concentration of molecular oxygen - was shown, and the participation of singlet oxygen, hydroxyl radicals and superoxide (hydroperoxide) radicals in this process was testified. Laser radiation-induced ROS in solutions of blood serum proteins, bovine serum albumin and bovine gamma-globulin, cause the formation of long-lived reactive protein species (LRPS) with a half-life of about 4h. The generation of LRPS caused by laser irradiation results in prolonged several-hour generation of ROS - hydrogen peroxide, hydroxyl and superoxide radicals. As affected by LRPS, coupled radical reactions lead to conversion of dissolved molecular oxygen to hydrogen peroxide. Irradiation with light sources away from the oxygen absorption band is not attended by formation of ROS and LRPS. A consideration is provided for the possible molecular mechanisms of ROS formation under the influence of He-Ne laser irradiation, the role of proteins in their generation and the biological significance of these processes. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Menaquinone as pool quinone in a purple bacterium

    PubMed Central

    Schoepp-Cothenet, Barbara; Lieutaud, Clément; Baymann, Frauke; Verméglio, André; Friedrich, Thorsten; Kramer, David M.; Nitschke, Wolfgang

    2009-01-01

    Purple bacteria have thus far been considered to operate light-driven cyclic electron transfer chains containing ubiquinone (UQ) as liposoluble electron and proton carrier. We show that in the purple γ-proteobacterium Halorhodospira halophila, menaquinone-8 (MK-8) is the dominant quinone component and that it operates in the QB-site of the photosynthetic reaction center (RC). The redox potentials of the photooxidized pigment in the RC and of the Rieske center of the bc1 complex are significantly lower (Em = +270 mV and +110 mV, respectively) than those determined in other purple bacteria but resemble those determined for species containing MK as pool quinone. These results demonstrate that the photosynthetic cycle in H. halophila is based on MK and not on UQ. This finding together with the unusual organization of genes coding for the bc1 complex in H. halophila suggests a specific scenario for the evolutionary transition of bioenergetic chains from the low-potential menaquinones to higher-potential UQ in the proteobacterial phylum, most probably induced by rising levels of dioxygen 2.5 billion years ago. This transition appears to necessarily proceed through bioenergetic ambivalence of the respective organisms, that is, to work both on MK- and on UQ-pools. The establishment of the corresponding low- and high-potential chains was accompanied by duplication and redox optimization of the bc1 complex or at least of its crucial subunit oxidizing quinols from the pool, the Rieske protein. Evolutionary driving forces rationalizing the empirically observed redox tuning of the chain to the quinone pool are discussed. PMID:19429705

  5. Quinones and aromatic chemical compounds in particulate matter induce mitochondrial dysfunction: implications for ultrafine particle toxicity.

    PubMed

    Xia, Tian; Korge, Paavo; Weiss, James N; Li, Ning; Venkatesen, M Indira; Sioutas, Constantinos; Nel, Andre

    2004-10-01

    Particulate pollutants cause adverse health effects through the generation of oxidative stress. A key question is whether these effects are mediated by the particles or their chemical compounds. In this article we show that aliphatic, aromatic, and polar organic compounds, fractionated from diesel exhaust particles (DEPs), exert differential toxic effects in RAW 264.7 cells. Cellular analyses showed that the quinone-enriched polar fraction was more potent than the polycyclic aromatic hydrocarbon (PAH)-enriched aromatic fraction in O2 .- generation, decrease of membrane potential (Delta-Psi m), loss of mitochondrial membrane mass, and induction of apoptosis. A major effect of the polar fraction was to promote cyclosporin A (CsA)-sensitive permeability transition pore (PTP) opening in isolated liver mitochondria. This opening effect is dependent on a direct effect on the PTP at low doses as well as on an effect on Delta-Psi m at high doses in calcium (Ca2+)-loaded mitochondria. The direct PTP effect was mimicked by redox-cycling DEP quinones. Although the aliphatic fraction failed to perturb mitochondrial function, the aromatic fraction increased the Ca2+ retention capacity at low doses and induced mitochondrial swelling and a decrease in Delta-Psi m at high doses. This swelling effect was mostly CsA insensitive and could be reproduced by a mixture of PAHs present in DEPs. These chemical effects on isolated mitochondria could be reproduced by intact DEPs as well as ambient ultrafine particles (UFPs). In contrast, commercial polystyrene nanoparticles failed to exert mitochondrial effects. These results suggest that DEP and UFP effects on the PTP and Delta-Psi m are mediated by adsorbed chemicals rather than the particles themselves.

  6. Quinones and Aromatic Chemical Compounds in Particulate Matter Induce Mitochondrial Dysfunction: Implications for Ultrafine Particle Toxicity

    PubMed Central

    Xia, Tian; Korge, Paavo; Weiss, James N.; Li, Ning; Venkatesen, M. Indira; Sioutas, Constantinos; Nel, Andre

    2004-01-01

    Particulate pollutants cause adverse health effects through the generation of oxidative stress. A key question is whether these effects are mediated by the particles or their chemical compounds. In this article we show that aliphatic, aromatic, and polar organic compounds, fractionated from diesel exhaust particles (DEPs), exert differential toxic effects in RAW 264.7 cells. Cellular analyses showed that the quinone-enriched polar fraction was more potent than the polycyclic aromatic hydrocarbon (PAH)–enriched aromatic fraction in O2•− generation, decrease of membrane potential (ΔΨm), loss of mitochondrial membrane mass, and induction of apoptosis. A major effect of the polar fraction was to promote cyclosporin A (CsA)–sensitive permeability transition pore (PTP) opening in isolated liver mitochondria. This opening effect is dependent on a direct effect on the PTP at low doses as well as on an effect on ΔΨm at high doses in calcium (Ca2+)-loaded mitochondria. The direct PTP effect was mimicked by redox-cycling DEP quinones. Although the aliphatic fraction failed to perturb mitochondrial function, the aromatic fraction increased the Ca2+ retention capacity at low doses and induced mitochondrial swelling and a decrease in ΔΨm at high doses. This swelling effect was mostly CsA insensitive and could be reproduced by a mixture of PAHs present in DEPs. These chemical effects on isolated mitochondria could be reproduced by intact DEPs as well as ambient ultrafine particles (UFPs). In contrast, commercial polystyrene nanoparticles failed to exert mitochondrial effects. These results suggest that DEP and UFP effects on the PTP and ΔΨm are mediated by adsorbed chemicals rather than the particles themselves. PMID:15471724

  7. Terpenoids from Diplophyllum taxifolium with quinone reductase-inducing activity.

    PubMed

    Wang, Xiao; Zhang, Jiao-Zhen; Zhou, Jin-Chuan; Shen, Tao; Lou, Hong-Xiang

    2016-03-01

    Two new ent-prenylaromadendrane-type diterpenoids, diplotaxifols A (1) and B (2), a new ent-eudesmol, ent-eudesma-4(15),11(13)-dien-6α,12-diol (3), eight new eudesmanolides enantiomers (4-11) of the corresponding compounds from higher plants along with four known ent-eudesmanolides (12-15) were isolated from the 95% EtOH extract of Chinese liverwort Diplophyllum taxifolium. Their structures were elucidated on the basis of MS, NMR and IR spectral data, and confirmed by single-crystal X-ray diffraction analysis. The quinone reductase-inducing activity of the compounds was evaluated.

  8. A new sesquiterpenoid quinone with cytotoxicity from Abelmoschus sagittifolius.

    PubMed

    Chen, De-Li; Zhang, Xiao-Po; Ma, Guo-Xu; Wu, Hai-Feng; Yang, Jun-Shan; Xu, Xu-Dong

    2016-01-01

    A new sesquiterpenoid quinone, Acyl hibiscone B (1), together with five known compounds, (R)-lasiodiplodin (2), (R)-de-O-methyllasiodiplodin, (3) dibutyl phthalate (4), (R)-9-phenylnonan-2-ol (5) and hibiscone B (6), was obtained from the stem tuber of Abelmoschus sagittifolius. The structure of compound 1 was elucidated by analysing its (1)H and (13)C NMR, (1)H-(1)H COSY, HSQC, HMBC, NOESY and HR-ESI-MS values. Compound 1 showed significant cytotoxicity against Hela and HepG-2 human cancer cell lines.

  9. Liquid Quinones for Solvent-Free Redox Flow Batteries.

    PubMed

    Shimizu, Akihiro; Takenaka, Keisuke; Handa, Naoyuki; Nokami, Toshiki; Itoh, Toshiyuki; Yoshida, Jun-Ichi

    2017-09-08

    Liquid benzoquinone and naphthoquinone having diethylene glycol monomethyl ether groups are designed and synthesized as redox active materials that dissolve supporting electrolytes. The Li-ion batteries based on the liquid quinones using LiBF4 /PC show good performance in terms of voltage, capacity, energy efficiency, and cyclability in both static and flow modes. A battery is constructed without using intentionally added organic solvent, and its high energy density (264 W h L(-1) ) demonstrates the potential of solvent-free organic redox flow batteries using liquid active materials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Electronic Connection Between the Quinone and Cytochrome c Redox Pools and Its Role in Regulation of Mitochondrial Electron Transport and Redox Signaling

    PubMed Central

    Sarewicz, Marcin; Osyczka, Artur

    2015-01-01

    Mitochondrial respiration, an important bioenergetic process, relies on operation of four membranous enzymatic complexes linked functionally by mobile, freely diffusible elements: quinone molecules in the membrane and water-soluble cytochromes c in the intermembrane space. One of the mitochondrial complexes, complex III (cytochrome bc1 or ubiquinol:cytochrome c oxidoreductase), provides an electronic connection between these two diffusible redox pools linking in a fully reversible manner two-electron quinone oxidation/reduction with one-electron cytochrome c reduction/oxidation. Several features of this homodimeric enzyme implicate that in addition to its well-defined function of contributing to generation of proton-motive force, cytochrome bc1 may be a physiologically important point of regulation of electron flow acting as a sensor of the redox state of mitochondria that actively responds to changes in bioenergetic conditions. These features include the following: the opposing redox reactions at quinone catalytic sites located on the opposite sides of the membrane, the inter-monomer electronic connection that functionally links four quinone binding sites of a dimer into an H-shaped electron transfer system, as well as the potential to generate superoxide and release it to the intermembrane space where it can be engaged in redox signaling pathways. Here we highlight recent advances in understanding how cytochrome bc1 may accomplish this regulatory physiological function, what is known and remains unknown about catalytic and side reactions within the quinone binding sites and electron transfers through the cofactor chains connecting those sites with the substrate redox pools. We also discuss the developed molecular mechanisms in the context of physiology of mitochondria. PMID:25540143

  11. Reactivity of Cations and Zwitterions Formed in Photochemical and Acid-Catalyzed Reactions from m-Hydroxycycloalkyl-Substituted Phenol Derivatives.

    PubMed

    Cindro, Nikola; Antol, Ivana; Mlinarić-Majerski, Kata; Halasz, Ivan; Wan, Peter; Basarić, Nikola

    2015-12-18

    Three m-substituted phenol derivatives, each with a labile benzylic alcohol group and bearing either protoadamantyl 4, homoadamantyl 5, or a cyclohexyl group 6, were synthesized and their thermal acid-catalyzed and photochemical solvolytic reactivity studied, using preparative irradiations, fluorescence measurements, nanosecond laser flash photolysis, and quantum chemical calculations. The choice of m-hydroxy-substitution was driven by the potential for these phenolic systems to generate m-quinone methides on photolysis, which could ultimately drive the excited-state pathway, as opposed to forming simple benzylic carbocations in the corresponding thermal route. Indeed, thermal acid-catalyzed reactions gave the corresponding cations, which undergo rearrangement and elimination from 4, only elimination from 5, and substitution and elimination from 6. On the other hand, upon photoexcitation of 4-6 to S1 in a polar protic solvent, proton dissociation from the phenol, coupled with elimination of the benzylic OH (as hydroxide ion) gave zwitterions (formal m-quinone methides). The zwitterions exhibit reactivity different from the corresponding cations due to a difference in charge distribution, as shown by DFT calculations. Thus, protoadamantyl zwitterion has a less nonclassical character than the corresponding cation, so it does not undergo 1,2-shift of the carbon atom, as observed in the acid-catalyzed reaction.

  12. Nebivolol prevents ethanol-induced reactive oxygen species generation and lipoperoxidation in the rat kidney by regulating NADPH oxidase activation and expression.

    PubMed

    do Vale, Gabriel T; Gonzaga, Natália A; Simplicio, Janaina A; Tirapelli, Carlos R

    2017-03-15

    We studied whether the β1-adrenergic antagonist nebivolol would prevent ethanol-induced reactive oxygen species generation and lipoperoxidation in the rat renal cortex. Male Wistar rats were treated with ethanol (20% v/v) for 2 weeks. Nebivolol (10mg/kg/day; p.o. gavage) prevented both the increase in superoxide anion (O2(-)) generation and thiobarbituric acid reactive substances (TBARS) concentration induced by ethanol in the renal cortex. Ethanol decreased nitrate/nitrite (NOx) concentration in the renal cortex, and nebivolol prevented this response. Nebivolol did not affect the reduction of hydrogen peroxide (H2O2) concentration induced by ethanol. Nebivolol prevented the ethanol-induced increase of catalase (CAT) activity. Both SOD activity and the levels of reduced glutathione (GSH) were not affected by treatment with nebivolol or ethanol. Neither ethanol nor nebivolol affected the expression of Nox1, Nox4, eNOS, nNOS, CAT, Nox organizer 1 (Noxo1), c-Src, p47(phox) or superoxide dismutase (SOD) isoforms in the renal cortex. On the other hand, treatment with ethanol increased Nox2 expression, and nebivolol prevented this response. Finally, nebivolol reduced the expression of protein kinase (PK) Cδ and Rac1. The major finding of our study is that nebivolol prevented ethanol-induced reactive oxygen species generation and lipoperoxidation in the kidney by a mechanism that involves reduction on the expression of Nox2, a catalytic subunit of NADPH oxidase. Additionally, we demonstrated that nebivolol reduces NADPH oxidase-derived reactive oxygen species by decreasing the expression of PKCδ and Rac1, which are important activators of NADPH oxidase. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Evaluation of reactive oxygen species generating AirOcare system for reducing airborne microbial populations in a meat processing plant

    USDA-ARS?s Scientific Manuscript database

    The microbial contamination of meat and meat products is of continuing concern to the meat industry and regulatory agencies. Air has been established as a source of microbial contamination in slaughter and processing facilities. The objective of this research was to determine the efficacy of reactiv...

  14. Dietary pyrroloquinoline quinone (PQQ) alters indicators of inflammation and mitochondrial-related metabolism in human subjects.

    PubMed

    Harris, Calliandra B; Chowanadisai, Winyoo; Mishchuk, Darya O; Satre, Mike A; Slupsky, Carolyn M; Rucker, Robert B

    2013-12-01

    Pyrroloquinoline quinone (PQQ) influences energy-related metabolism and neurologic functions in animals. The mechanism of action involves interactions with cell signaling pathways and mitochondrial function. However, little is known about the response to PQQ in humans. Using a crossover study design, 10 subjects (5 females, 5 males) ingested PQQ added to a fruit-flavored drink in two separate studies. In study 1, PQQ was given in a single dose (0.2 mg PQQ/kg). Multiple measurements of plasma and urine PQQ levels and changes in antioxidant potential [based on total peroxyl radical-trapping potential and thiobarbituric acid reactive product (TBAR) assays] were made throughout the period of 48 h. In study 2, PQQ was administered as a daily dose (0.3 mg PQQ/kg). After 76 h, measurements included indices of inflammation [plasma C-reactive protein, interleukin (IL)-6 levels], standard clinical indices (e.g., cholesterol, glucose, high-density lipoprotein, low-density lipoprotein, triglycerides, etc.) and (1)H-nuclear magnetic resonance estimates of urinary metabolites related in part to oxidative metabolism. The standard clinical indices were normal and not altered by PQQ supplementation. However, dietary PQQ exposure (Study 1) resulted in apparent changes in antioxidant potential based on malonaldehyde-related TBAR assessments. In Study 2, PQQ supplementation resulted in significant decreases in the levels of plasma C-reactive protein, IL-6 and urinary methylated amines such as trimethylamine N-oxide, and changes in urinary metabolites consistent with enhanced mitochondria-related functions. The data are among the first to link systemic effects of PQQ in animals to corresponding effects in humans. © 2013.

  15. Syntheses of covalently-linked porphyria-quinone complexes. I

    SciTech Connect

    Kong, J.L.Y.; Loach, P.A.

    1980-06-01

    A synthetic route for the preparation of covalently-linked prophyin-quinone and metalloporphyrinquinone complexes as models for the phototrap in bacterial photosynthesis is described. 5(5-Carboxyphenyl)-10,15,20-tritolylporphyrin, prepared by a mixed aldehyde approach, was attached to benzoquinone center with a propanediol bridge by means of ester linkages. The starting point for the benzoquinone moiety was 2,5-dihydroxyphenylacetic acid, whose hydroquinone function was first protected by preparing its dimethyl ether. The spacing between the two centers of the complex could be altered simply by varying the length of the bridging group (a diol) employed. Boron tribomide was used to unmask the quinol derivatives in the final coupled products. The zinc(II) derivative of porphyrin-quinone complex was prepared by addition of a saturated solution of zinc acetate in methanol to a solution of the corresponding prophyrin-hydroqyuinone complex in dichloromethane at room temperature. The structures of these complexes were confirmed by nmr spectroscopy, uv-visible absorption, and mass spectroscopy. Oxidation of the quinol moiety in the covalently-linked complex to its corresponding quinonoid derivative was accomplished by treating a solution of the complex in dichloromethane with a stoichiometric amount of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, a high potential benzoquinone.

  16. Atypical features of Thermus thermophilus succinate:quinone reductase.

    PubMed

    Kolaj-Robin, Olga; Noor, Mohamed R; O'Kane, Sarah R; Baymann, Frauke; Soulimane, Tewfik

    2013-01-01

    The Thermus thermophilus succinate:quinone reductase (SQR), serving as the respiratory complex II, has been homologously produced under the control of a constitutive promoter and subsequently purified. The detailed biochemical characterization of the resulting wild type (wt-rcII) and His-tagged (rcII-His(8)-SdhB and rcII-SdhB-His(6)) complex II variants showed the same properties as the native enzyme with respect to the subunit composition, redox cofactor content and sensitivity to the inhibitors malonate, oxaloacetate, 3-nitropropionic acid and nonyl-4-hydroxyquinoline-N-oxide (NQNO). The position of the His-tag determined whether the enzyme retained its native trimeric conformation or whether it was present in a monomeric form. Only the trimer exhibited positive cooperativity at high temperatures. The EPR signal of the [2Fe-2S] cluster was sensitive to the presence of substrate and showed an increased rhombicity in the presence of succinate in the native and in all recombinant forms of the enzyme. The detailed analysis of the shape of this signal as a function of pH, substrate concentration and in the presence of various inhibitors and quinones is presented, leading to a model for the molecular mechanism that underlies the influence of succinate on the rhombicity of the EPR signal of the proximal iron-sulfur cluster.

  17. Study of quinones reactions with wine nucleophiles by cyclic voltammetry.

    PubMed

    Oliveira, Carla M; Barros, António S; Ferreira, António C S; Silva, Artur M S

    2016-11-15

    Quinones are electrophilic species which can react with various nucleophiles, like wine antioxidants, such as sulfur dioxide or ascorbic acid, thiols, amino acids, and numerous polyphenols. These reactions are very important in wine aging because they mediate oxygen reactions during both production and bottle aging phases. In this work, the major challenge was to determine the interaction between ortho-quinones and wine nucleophiles (amino acids, thiols, and the antioxidants SO2 and ascorbic acid), by cyclic voltammetry. Wine-model solutions with gallic acid, caffeic acid, or (+)-catechin and nucleophilic compounds were used. To understand the effect of nucleophilic addition in wine, a white wine with the same added nucleophiles was also analysed. Cyclic voltammograms were taken with glassy carbon electrode or screen-printed carbon electrodes, respectively, for wine-model and white wines solutions, in the absence and in the presence of nucleophiles. A nucleophilic order profile related to the cathodic current intensity decrease was observed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Crystal structure and characterization of pyrroloquinoline quinone disodium trihydrate

    PubMed Central

    2012-01-01

    Background Pyrroloquinoline quinone (PQQ), a tricarboxylic acid, has attracted attention as a growth factor, and its application to supplements and cosmetics is underway. The product used for these purposes is a water-soluble salt of PQQ disodium. Although in the past, PQQ disodiumpentahydrates with a high water concentration were used, currently, low hydration crystals of PQQ disodiumpentahydrates are preferred. Results We prepared a crystal of PQQ disodium trihydrate in a solution of ethanol and water, studied its structure, and analyzed its properties. In the prepared crystal, the sodium atom interacted with the oxygen atom of two carboxylic acids as well as two quinones of the PQQ disodium trihydrate. In addition, the hydration water of the prepared crystal was less than that of the conventional PQQ disodium crystal. From the results of this study, it was found that the color and the near-infrared (NIR) spectrum of the prepared crystal changed depending on the water content in the dried samples. Conclusions The water content in the dried samples was restored to that in the trihydrate crystal by placing the samples in a humid environment. In addition, the results of X-ray diffraction (XRD) and X-ray diffraction-differential calorimetry (XRD-DSC) analyses show that the phase of the trihydrate crystal changed when the crystallization water was eliminated. The dried crystal has two crystalline forms that are restored to the original trihydrate crystals in 20% relative humidity (RH). This crystalline (PQQ disodium trihydrate) is stable under normal environment. PMID:22713213

  19. Enhancing the Performance of Vanadium Redox Flow Batteries using Quinones

    NASA Astrophysics Data System (ADS)

    Mulcahy, James W., III

    The global dependence on fossil fuels continues to increase while the supply diminishes, causing the proliferation in demand for renewable energy sources. Intermittent renewable energy sources such as wind and solar, require electrochemical storage devices in order to transfer stored energy to the power grid at a constant output. Redox flow batteries (RFB) have been studied extensively due to improvements in scalability, cyclability and efficiency over conventional batteries. Vanadium redox flow batteries (VRFB) provide one of the most comprehensive solutions to energy storage in relation to other RFBs by alleviating the problem of cross-contamination. Quinones are a class of organic compounds that have been extensively used in chemistry, biochemistry and pharmacology due to their catalytic properties, fast proton-coupled electron transfer, good chemical stability and low cost. Anthraquinones are a subcategory of quinones and have been utilized in several battery systems. Anthraquinone-2, 6-disulfonic acid (AQDS) was added to a VRFB in order to study its effects on cyclical performance. This study utilized carbon paper electrodes and a Nafion 117 ion exchange membrane for the membrane-electrode assembly (MEA). The cycling performance was investigated over multiple charge and discharge cycles and the addition of AQDS was found to increase capacity efficiency by an average of 7.6% over the standard VRFB, while decreasing the overall cycle duration by approximately 18%. It is thus reported that the addition of AQDS to a VRFB electrolyte has the potential to increase the activity and capacity with minimal increases in costs.

  20. Universal quinone electrodes for long cycle life aqueous rechargeable batteries

    NASA Astrophysics Data System (ADS)

    Liang, Yanliang; Jing, Yan; Gheytani, Saman; Lee, Kuan-Yi; Liu, Ping; Facchetti, Antonio; Yao, Yan

    2017-08-01

    Aqueous rechargeable batteries provide the safety, robustness, affordability, and environmental friendliness necessary for grid storage and electric vehicle operations, but their adoption is plagued by poor cycle life due to the structural and chemical instability of the anode materials. Here we report quinones as stable anode materials by exploiting their structurally stable ion-coordination charge storage mechanism and chemical inertness towards aqueous electrolytes. Upon rational selection/design of quinone structures, we demonstrate three systems that coupled with industrially established cathodes and electrolytes exhibit long cycle life (up to 3,000 cycles/3,500 h), fast kinetics (>=20C), high anode specific capacity (up to 200-395 mAh g-1), and several examples of state-of-the-art specific energy/energy density (up to 76-92 Wh kg-1/ 161-208 Wh l-1) for several operational pH values (-1 to 15), charge carrier species (H+, Li+, Na+, K+, Mg2+), temperature (-35 to 25 °C), and atmosphere (with/without O2), making them a universal anode approach for any aqueous battery technology.

  1. Antiprotozoal isoflavan quinones from Abrus precatorius ssp. africanus.

    PubMed

    Hata, Yoshie; Raith, Melanie; Ebrahimi, Samad Nejad; Zimmermann, Stefanie; Mokoka, Tsholofelo; Naidoo, Dashnie; Fouche, Gerda; Maharaj, Vinesh; Kaiser, Marcel; Brun, Reto; Hamburger, Matthias

    2013-04-01

    A library of 206 extracts from selected South African plants was screened in vitro against a panel of protozoan parasites, Plasmodium falciparum, Trypanosoma brucei rhodesiense, and Leishmania donovani. A CH2Cl2/MeOH (1 : 1) extract of Abrus precatorius L. ssp. africanus strongly inhibited P. falciparum (98 %), T. b. rhodesiense (100 %), and L. donovani (76 %) when tested at a concentration of 10.0 µg/mL. The active constituents were tracked by HPLC-based activity profiling and isolated by preparative and semipreparative RP-HPLC chromatography. Structures were established by HR-ESIMS, and 1D and 2D NMR (1H, 13C, COSY, HMBC, HSQC, and NOE difference spectroscopy). Five compounds were obtained and identified as two isoflavan hydroquinones, abruquinone H (1) and abruquinone G (2), and three isoflavan quinones, abruquinone I (3), abruquinone B (4), and 7,8,3''5'-tetramethoxyisoflavan-1',4'-quinone (5). Compounds 1 and 3 were new natural products. The absolute configuration of compounds was determined by comparison of electronic circular dichroism spectra with calculated ECD data. Compounds 3 and 4 showed strong activity against T. b. rhodesiense (IC50 values of 0.30 and 0.16 µM, respectively) and good selectivity (selectivity indices of 73.7 and 50.5, respectively). Georg Thieme Verlag KG Stuttgart · New York.

  2. GIPC mediates the generation of reactive oxygen species and the regulation of cancer cell proliferation by insulin-like growth factor-1/IGF-1R signaling.

    PubMed

    Choi, Ji Seung; Paek, A Rome; Kim, Soo Youl; You, Hye Jin