Generation Of Anion Radical Research Articles

Inhibition of diabetic-cataract by vitamin K1 involves modulation of hyperglycemia-induced alterations to lens calcium homeostasis

This study investigated the potential of vitamin K1 against streptozotocin-induced diabetic cataract in Wistar rats. A single, intraperitoneal injection of streptozotocin (STZ) (35 mg/kg) resulted in hyperglycemia, accumulation of sorbitol and formation of advanced glycation end product (AGE) in eye lens. Hyperglycemia in lens also resulted in superoxide anion and hydroxyl radical generation and less reduced glutathione suggesting oxidative stress in lens. Hyperglycemia also resulted in increase in lens Ca2+ and significant inhibition of lens Ca2+ ATPase activity. These changes were associated with cataract formation in diabetic animals. By contrast treatment of diabetic rats with vitamin K1 (5 mg/kg, sc, twice a week) resulted in animals with partially elevated blood glucose and with transparent lenses having normal levels of sorbitol, AGE, Ca2+ ATPase, Ca2+, and oxidative stress. Vitamin K 1 may function to protect against cataract formation in the STZ induced diabetic rat by affecting the homeostasis of blood glucose and minimizing subsequent oxidative and osmotic stress. Thus, these results show that Vitamin K1 inhibits diabetic-cataract by modulating lens Ca2+ homeostasis and its hypoglycemic effect through its direct action on the pancreas.

Effects of endogenous signals and Fusarium oxysporum on the mechanism regulating genistein synthesis and accumulation in yellow lupine and their impact on plant cell cytoskeleton.

The aim of the study was to examine cross-talk interactions of soluble sugars (sucrose, glucose and fructose) and infection caused by Fusarium oxysporum f.sp. lupini on the synthesis of genistein in embryo axes of Lupinus luteus L.cv. Juno. Genistein is a free aglycone, highly reactive and with the potential to inhibit fungal infection and development of plant diseases. As signal molecules, sugars strongly stimulated accumulation of isoflavones, including genistein, and the expression of the isoflavonoid biosynthetic genes. Infection significantly enhanced the synthesis of genistein and other isoflavone aglycones in cells of embryo axes of yellow lupine with high endogenous sugar levels. The activity of β-glucosidase, the enzyme that releases free aglycones from their glucoside bindings, was higher in the infected tissues than in the control ones. At the same time, a very strong generation of the superoxide anion radical was observed in tissues with high sugar contents already in the initial stage of infection. During later stages after inoculation, a strong generation of semiquinone radicals was observed, which level was relatively higher in tissues deficient in sugars than in those with high sugar levels. Observations of actin and tubulin cytoskeletons in cells of infected embryo axes cultured on the medium with sucrose, as well as the medium without sugar, showed significant differences in their organization.

An ESR study on superoxide radical anion generation and its involvement in the photooxidative degradation of poly-3-hexylthiophene in chlorobenzene solution

The photooxidative degradation of poly-3-hexylthiophene (P3HT) in chlorobenzene solution containing dissolved oxygen was performed at room temperature. The generation of superoxide radical anion (O2−) during the photooxidation of P3HT was verified by ESR measurements using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as the spin trap. The changes in mass spectra determined by MALDI-TOF MS showed that P3HT photodegradation was prevented in the presence of DMPO. Kinetics analysis shows that the prevention of P3HT photodegradation is due to the scavenging of O2− by DMPO. Therefore, the involvement of O2− in the initial step of P3HT photodegradation could be concluded.

The role of reactive oxygen species and calcium ions in the implementation of the stress-protective effect of brassinosteroids on plant cells

The effect of the brassinosteroids (BS) 24-epibrassiniolide and 24-epicastasterone on the thermoresistance of wheat coleoptile (Triticum aestivum L.) and their generation of the superoxide anion radical and antioxidant enzymes activity were investigated. The treatment of coleoptiles with 10 nM solutions of BS caused a transient increase in O2·- generation and a subsequent increase in the activity of superoxide dismutase and catalase and an improvement in heat resistance. Pretreatment of coleoptiles with the NADPH oxidase inhibitor imidazole leveled the increase in production of the superoxide anion radical and prevented an increase in the activity of antioxidant enzymes and the development of cell thermostability. The investigated effects of BS were also depressed by the pretreatment of coleoptile segments with extracellular calcium chelator EGTA and inhibitor of ADP-ribosyl cyclase nicotinamide. A conclusion was made about the participation of calcium ions and reactive oxygen species generated by the action of NADPH oxidase in the implementation of the stress-protective effect of the BS in the cells of wheat coleoptile.

Fast synthesis of high-quality reduced graphene oxide at room temperature under light exposure.

An approach of presenting new reducing reagents, sodium-benzophenone (Na-B) or Na-B in the presence of the hydrazine (Na-B-H) system under light exposure could produce rGOs with/without N-doping at room temperature in both the solution phase and on a solid substrate. Benzophenone activated those solutions acting as a photosensitizer under light. It was assumed that the newly generated radical anions with electrons from Na-B under light can reduce GO to rGO sheets (rGONa-B1). In addition, the Na-B-H system can allow a higher degree of reduction with the doping of nitrogen atoms by the introduction of hydrazine to produce radical anions and electrons with a sodium hydrazide complex, which helps decrease the sheet resistance of the as-made rGONa-B-H2. The excellent properties (very low oxygen content (C/O ∼16.2), and low sheet resistance (∼130 Ω square(-1))) of the rGOs were confirmed by XPS, XRD, IR, Raman spectroscopy, TGA, wettability, and sheet resistance measurements. High-quality rGO films on flexible substrates could be prepared by directly immersing the GO films in these solutions for several minutes.

Ciprofloxacin oxidation by UV-C activated peroxymonosulfate in wastewater

This work aimed at demonstrating the advantages to use sulfate radical anion for eliminating ciprofloxacin residues from treated domestic wastewater by comparing three UV-254nm based advanced oxidation processes: UV/persulfate (PDS), UV/peroxymonosulfate (PMS) and UV/H2O2. In distilled water, the order of efficiency was UV/PDS>UV/PMS>UV/H2O2 while in wastewater, the most efficient process was UV/PMS followed by UV/PDS and UV/H2O2 mainly because PMS decomposition into sulfate radical anion was activated by bicarbonate ions. CIP was fully degraded in wastewater at pH 7 in 60min for a [PMS]/[CIP] molar ratio of 20. Nine transformation products were identified by liquid chromatography–high resolution-mass spectrometry allowing for the establishment of degradation pathways in the UV/PMS system. Sulfate radical anion attacks prompted transformations at the piperazinyl ring through a one electron oxidation mechanism as a major pathway while hydroxyl radical attacks were mainly responsible for quinolone moiety transformations as a minor pathway. Sulfate radical anion generation has made UV/PMS a kinetically effective process in removing ciprofloxacin from wastewater with the elimination of ciprofloxacin antibacterial activity.

Beneficial Effect of Sesame Oil on Heavy Metal Toxicity

Heavy metals become toxic when they are not metabolized by the body and accumulate in the soft tissue. Chelation therapy is mainly for the management of heavy metal-induced toxicity; however, it usually causes adverse effects or completely blocks the vital function of the particular metal chelated. Much attention has been paid to the development of chelating agents from natural sources to counteract lead- and iron-induced hepatic and renal damage. Sesame oil (a natural edible oil) and sesamol (an active antioxidant) are potently beneficial for treating lead- and iron-induced hepatic and renal toxicity and have no adverse effects. Sesame oil and sesamol significantly inhibit iron-induced lipid peroxidation by inhibiting the xanthine oxidase, nitric oxide, superoxide anion, and hydroxyl radical generation. In addition, sesame oil is a potent inhibitor of proinflammatory mediators, and it attenuates lead-induced hepatic damage by inhibiting nitric oxide, tumor necrosis factor-α, and interleukin-1β levels. Because metal chelating therapy is associated with adverse effects, treating heavy metal toxicity in addition with sesame oil and sesamol may be better alternatives. This review deals with the possible use and beneficial effects of sesame oil and sesamol during heavy metal toxicity treatment.

Role of hydrogen peroxide in generation of a signal inducing heat tolerance of wheat seedlings

The effects of 1-min-long exposure to 42°C (hardening heating) on heat tolerance and dynamics of ROS (superoxide anion radical and hydrogen peroxide) generation were investigated in the wheat (Triticum aestivum L., cv. Elegiya) seedlings. During the initial 5–30 min after the onset of hyperthermia, ROS generation by roots and shoots was intensified, and superoxide dismutase (SOD) was activated. During the first hour after hardening heating, the seedling tolerance to injurious 10-min-long treatment with high temperature (46°C) decreased but subsequently it gradually rose, reaching maximum in 24 h. Transient accumulation of hydrogen peroxide induced by hardening was suppressed by seedling treatment with H2O2 scavenger dimethylthiourea, by inhibitors of NADPH-oxidase (imidazole) and DDC (sodium diethyldithiocarbamate). These compounds considerably reduced favorable effect of hardening on seedling heat tolerance. It was concluded that generation of a signal inducing the development of heat tolerance depended on NADPH-oxidase producing superoxide anion radical and SOD that transforms it into hydrogen peroxide (more stable ROS performing signaling functions).

Isolation of Neutrophils/Assay of O2- (Superoxide Anion Radical)Generation by Cytochrome-C Reduction

.(superoxide anion radical) adherence to endothelial cells, migration, lysosomal enzyme release, and cytocidal activity. The enhancement of neutrophil responses in this fashion has been termed ‘priming'. Here, we describe procedures for the preparation of human peripheral neutrophils and for the analysis of cytokine-induced priming of neutrophils monitored by measuring . O 2 generation. Protocol Isolation of neutrophils

Stable Radical Trianions from Reversibly Formed Sigma-Dimers of Selenadiazoloquinolones Studied by In Situ EPR/UV–vis Spectroelectrochemistry and Quantum Chemical Calculations

The redox behavior of the series of 7-substituted 6-oxo-6,9-dihydro[1,2,5]selenadiazolo[3,4-h]quinolines and 8-substituted 9-oxo-6,9-dihydro[1,2,5]selenadiazolo[3,4-f]quinolines with R(7), R(8) = H, COOC(2)H(5), COOCH(3), COOH, COCH(3), and CN has been studied by in situ EPR and EPR/UV-vis spectroelectrochemistry in dimethylsulfoxide. All selenadiazoloquinolones undergo a one-electron reduction process to form the corresponding radical anions. Their stability strongly depends on substitution at the nitrogen atom of the 4-pyridone ring. The primary generated radical anions from N-ethyl-substituted quinolones are stable, whereas for the quinolones with imino hydrogen, the initial radical anions rapidly dimerize to produce unusually stable sigma-dimer (σ-dimer) dianions. These are reversibly oxidized to the initial compounds at potentials considerably less negative than the original reduction process in the back voltammetric scan. The dimer dianion can be further reduced to the stable paramagnetic dimer radical trianion in the region of the second reversible reduction step. The proposed complex reaction mechanism was confirmed by in situ EPR/UV-vis cyclovoltammetric experiments. The site of the dimerization in the σ-dimer and the mapping of the unpaired spin density both for radical anions and σ-dimer radical trianions with unusual unpaired spin distribution have been assigned by means of density functional theory calculations.

Covalently synthesized graphene oxide-aptamer nanosheets for efficient visible-light photocatalysis of nucleic acids and proteins of viruses

A novel photocatalyst, graphene oxide (GO) functioned aptamer, was covalently synthesized and characterized as being composed of photosensitive GO and target recognition aptamer. Aptamer enhanced photocatalytic activities of GO were studied under broad visible-light spectrum. The complex photocatalyst effectively inactivated viruses, and damaged the proteins capsid and nucleic acids of viruses in irradiation. Subsequently, the proteins posed carbonylation and the nucleic acid bases (especially for guanosine) received oxidized modification. GO was reduced by loss of oxygen elements. GO-aptamer and viruses constituted a redox system under visible-light irradiation. The photocatalysis paths involved energy transfer (generation of singlet oxygen), electron transfer (generation of anion radicals) and water dissociation (generation of the precursor to the hydrated electron). GO-aptamer is a smart photocatalyst to selectively photocatalyze of nucleic acids and proteins, which is attractive in environment protection, biochemical engineering and phototherapy.

Inhibitory Effects and Mechanisms of Hydrilla verticillata (Linn.f.) Royle Extracts on Freshwater Algae

To pursue an effective way to control freshwater algae, four extracts from a submerged macrophyte Hydrilla verticillata (Linn.f.) Royle were tested to study its inhibitory effects on Anabaena flos-aquae FACHB-245 and Chlorella pyrenoidosa Chick FACHB-9. Extract with the highest inhibiting ability was further studied in order to reveal the inhibitory mechanism. The results demonstrated that H. verticillata extracts inhibited the growth of A. flos-aquae and C. pyrenoidosa, and methanol extract had the highest inhibiting ability. The mechanism underlying the algal growth inhibition involves the superoxide anion radical generation that induces the damage of cell wall and release of intracellular components.

Evaluation of Antioxidative Activity between CoQ10-Nanostructured Lipid Carrier and CoQ10 Cosmetic

Coenzyme Q10 (CoQ10) is a poorly water-soluble active ingredient with intrinsic chemical instability, but holds strongly antioxidative capacity. The CoQ10-NLC aqueous dispersion has been prepared, the antioxidative activity between CoQ10-NLC and CoQ10 cosmetic have been investigated, and several employed methods such as scavenging efficiency on DPPH radical and inhibition of superoxide anion and hydroxyl radical generation illustrated its potentially antioxidative activity. The test results displayed that CoQ10-NLC aqueous dispersion indicated higher antioxidative activity than commercially available CoQ10 cosmetic.

Detailed Electrochemical Analysis of the Redox Chemistry of Tetrafluorotetracyanoquinodimethane TCNQF4, the Radical Anion [TCNQF4]•–, and the Dianion [TCNQF4]2– in the Presence of Trifluoroacetic Acid

The electrochemistry of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (TCNQF(4)), [TCNQF(4)](•-), and [TCNQF(4)](2-) have been studied in acetonitrile (0.1 M [Bu(4)N][ClO(4)]). Transient and steady-state voltammetric techniques have been utilized to monitor the generation of [TCNQF(4)](•-) and [TCNQF(4)](2-) anions as well as their reactions with trifluoroacetic acid (TFA). In the absence of TFA, the reduction of TCNQF(4) occurs via two, diffusion controlled, chemically and electrochemically reversible, one-electron processes where the reversible formal potentials are 0.31 and -0.22 V vs Ag/Ag(+). Unlike the TCNQ analogues, both [TCNQF(4)](•-) and [TCNQF(4)](2-) are persistent when generated via bulk electrolysis even under aerobic conditions. Voltammetric and UV-vis data revealed that although the parent TCNQF(4) does not react with TFA, the electrochemically generated radical anion and dianion undergo facile protonation to yield [HTCNQF(4)](•), [HTCNQF(4)](-) and H(2)TCNQF(4) respectively. The voltammetry can be simulated to give a complete thermodynamic and kinetic description of the complex, coupled redox and acid-base chemistry. The data indicate dramatically different equilibrium and rate constants for the protonation of [TCNQF(4)](•-) (K(eq) = 3.9 × 10(-6), k(f) = 1.0 × 10(-3) M(-1) s(-1)) and [TCNQF(4)](2-) (K(eq) = 3.0 × 10(3), k(f) = 1.0 × 10(10) M(-1) s(-1)) in the presence of TFA.

Integration of the cyanobacterial DesA gene for Δ12-acyl-lipid desaturase improves potato tolerance to paraquat-induced oxidative stress

The effect of potato plant (Solanum tuberosum L., cv. Desnitsa) transformation with the desA gene from Synechocystis sp. PCC 6803, encoding Δ12 acyl-lipid desaturase, on the development of plant tolerance to oxidative stress was studied. To initiate oxidative stress, plants were treated with 1 mM paraquat; this treatment enhanced oxidative processes in both wild-type and transformed potato plants via the activation of superoxide anion-radical generation. This resulted in the activated oxidation of membrane lipids and the formation of a great amount of fatty acids with coupled double bonds (conjugated dienes, CD), further breakdown of lipid molecules, and enhanced production of MDA in tissues of wild-type and transformed plants. The characteristics of oxidative stress, including lipid peroxidation, were less pronounced in transformants as compared with wild-type plants. After treatment with paraquat, activities of main antioxidant enzymes (superoxide dismutase, catalase, and peroxidase) were much higher in wild-type than in transformed plants. Thus, expression of inserted heterologous desA gene for Δ12 acyl-lipid desaturase in potato plants resulted in improved tolerance of transformants to oxidative stress due to the more efficient maintenance of stable cell membrane structure functioning, and this permits prevention of electron “jump” to oxygen and, as a result, of accelerated ROS generation. More developed and regularly arranged chloroplast membrane system in transformants may also favor their improved tolerance.

Vitamin K3 and vitamin C alone or in combination induced apoptosis in leukemia cells by a similar oxidative stress signalling mechanism

BackgroundSecondary therapy-related acute lymphoblastic leukemia might emerge following chemotherapy and/or radiotherapy for primary malignancies. Therefore, other alternatives should be pursued to treat leukemia.ResultsIt is shown that vitamin K3- or vitamin C- induced apoptosis in leukemia cells by oxidative stress mechanism involving superoxide anion radical and hydrogen peroxide generation, activation of NF-κB, p53, c-Jun, protease caspase-3 activation and mitochondria depolarization leading to nuclei fragmentation. Cell death was more prominent when Jurkat and K562 cells are exposed to VC and VK3 in a ratio 1000:1 (10 mM: 10 μM) or 100:1 (300 μM: 3 μM), respectively.ConclusionWe provide for the first time in vitro evidence supporting a causative role for oxidative stress in VK3- and VC-induced apoptosis in Jurkat and K562 cells in a domino-like mechanism. Altogether these data suggest that VK3 and VC should be useful in the treatment of leukemia.

Response of blood platelets to resveratrol during a model of hyperhomocysteinemia

Resveratrol (3,4’,5-trihydroxystilben), a phenolic antioxidant synthesized in grapes and other plants, and also present in wine, has been suggested to help prevent cardiovascular events. In this study the influence of resveratrol on platelet aggregation during a model of hyperhomocysteinemia was investigated. We induced hyperhomocysteinemia using a reduced form of Hcys (final dose, 0.1 mM) and the most reactive form of Hcys, its cyclic thioester, homocysteine thiolactone (HTL, 1 µM). The aim of our study in vitro was also to investigate superoxide anion radical () generation after incubation of platelets with Hcys, HTL, and resveratrol. We have observed that HTL, like its precursor Hcys, stimulated the generation of in platelets and caused an augmentation of platelet aggregation induced by the strong physiological agonist thrombin. Our results in vitro also demonstrated that resveratrol reduced the toxic action of Hcys and HTL on blood platelet aggregation and superoxide anion radical production in platelets, suggesting its potential protective effects on hemostasis are negatively influenced by homocysteine and its derivatives.

Generation of Naphthoquinone Radical Anions by Electrospray Ionization: Solution, Gas-Phase, and Computational Chemistry Studies

Radical anions are present in several chemical processes, and understanding the reactivity of these species may be described by their thermodynamic properties. Over the last years, the formation of radical ions in the gas phase has been an important issue concerning electrospray ionization mass spectrometry studies. In this work, we report on the generation of radical anions of quinonoid compounds (Q) by electrospray ionization mass spectrometry. The balance between radical anion formation and the deprotonated molecule is also analyzed by influence of the experimental parameters (gas-phase acidity, electron affinity, and reduction potential) and solvent system employed. The gas-phase parameters for formation of radical species and deprotonated species were achieved on the basis of computational thermochemistry. The solution effects on the formation of radical anion (Q(•-)) and dianion (Q(2-)) were evaluated on the basis of cyclic voltammetry analysis and the reduction potentials compared with calculated electron affinities. The occurrence of unexpected ions [Q+15](-) was described as being a reaction between the solvent system and the radical anion, Q(•-). The gas-phase chemistry of the electrosprayed radical anions was obtained by collisional-induced dissociation and compared to the relative energy calculations. These results are important for understanding the formation and reactivity of radical anions and to establish their correlation with the reducing properties by electrospray ionization analyses.

Charged States of 1,3,5-Triazine Molecules as Models for Star-shaped Molecular Architecture: A DFT and Spectroelectrochemcial Study

The density functional theory calculations of molecular structure and spectroscopic and electronic properties of charged states in four triazine-heteroaryl star-shaped compounds are presented. The molecules end-capped with different heteroaryl groups, i.e., thiophene (TTT1), furan (TFT2), 3,4-ethylenedioxythienyl (TET3), and thiazole (TSNT4), were studied by electrochemical and in situ ESR/UV-vis-NIR spectroelectrochemical techniques in tetrahydrofuran/(TBA)BF(4). The charged states of monomers were created by cathodic reduction and the stability of generated anion radicals was characterized in detail both experimentally and theoretically. The TET3 molecule resulted in a star-shaped hyperbranched polymer formed anodically which in turn can be reversibly oxidized up to the tetracation. The nature and charge distribution of charge carriers at each redox state in the as-prepared polymer was clarified by calculations for the model (TET3)(3) trimer structure.

Exploring by Pulsed EPR the Electronic Structure of Ubisemiquinone Bound at the QH Site of Cytochrome bo3 from Escherichia coli with in Vivo13C-Labeled Methyl and Methoxy Substituents

The cytochrome bo(3) ubiquinol oxidase from Escherichia coli resides in the bacterial cytoplasmic membrane and catalyzes the two-electron oxidation of ubiquinol-8 and four-electron reduction of O(2) to water. The one-electron reduced semiquinone forms transiently during the reaction, and the enzyme has been demonstrated to stabilize the semiquinone. The semiquinone is also formed in the D75E mutant, where the mutation has little influence on the catalytic activity, and in the D75H mutant, which is virtually inactive. In this work, wild-type cytochrome bo(3) as well as the D75E and D75H mutant proteins were prepared with ubiquinone-8 (13)C-labeled selectively at the methyl and two methoxy groups. This was accomplished by expressing the proteins in a methionine auxotroph in the presence of l-methionine with the side chain methyl group (13)C-labeled. The (13)C-labeled quinone isolated from cytochrome bo(3) was also used for the generation of model anion radicals in alcohol. Two-dimensional pulsed EPR and ENDOR were used for the study of the (13)C methyl and methoxy hyperfine couplings in the semiquinone generated in the three proteins indicated above and in the model system. The data were used to characterize the transferred unpaired spin densities on the methyl and methoxy substituents and the conformations of the methoxy groups. In the wild type and D75E mutant, the constraints on the configurations of the methoxy side chains are similar, but the D75H mutant appears to have altered methoxy configurations, which could be related to the perturbed electron distribution in the semiquinone and the loss of enzymatic activity.