Oxygen Peroxide Research Articles

Effect of Electrolyte Contaminants and Surface Roughness on the Constant Phase Element

The origin of constant phase element (CPE) to explain electrode/electrolyte interface is subject of debate in the literature. CPE behavior is generally attributed to the presence of reactivity, surface inhomogeneity, various crystal planes and atomic scale defects in the crystal; all these may lead to dispersion of local capacitance at the electrode/electrolyte interface. Therefore, electrode/electrolyte interface of polycrystalline Pt (Pt-PC) and smooth glassy carbon disk electrode (GCE) are investigated in ultra-pure H2SO4 (0.5 M) electrolyte[1]. The surface of GCE is roughened mechanically to test the effect of roughness. The effect of intentional and unintentional contaminants are investigated using halide (Cl˗, Br-, I-) ions[2]. It is found that the CPE is affected by the concentration and nature of anion in the electrolyte. Unintentional impurities and cations do not affect the CPE behavior.[1] Singh, R. K., Devivaraprasad, R., Kar, T., Chakraborty, A., & Neergat, M. (2015). Electrochemical impedance spectroscopy of oxygen reduction reaction (ORR) in a rotating disk electrode configuration: effect of ionomer content and carbon-support. Journal of The Electrochemical Society, 162(6), F489.[2] Devivaraprasad, R., Ramesh, R., Naresh, N., Kar, T., Singh, R. K., & Neergat, M. (2014). Oxygen reduction reaction and peroxide generation on shape-controlled and polycrystalline platinum nanoparticles in acidic and alkaline electrolytes. Langmuir, 30(29), 8995-9006. Figure 1

Site-directed mutagenesis (P61G) of copper, zinc superoxide dismutase enhances its kinetic properties and tolerance to inactivation by H2O2

Superoxide dismutases (SODs) protect the cells by catalyzing the dismutation of harmful superoxide radicals (O2•-) into molecular oxygen (O2) and hydrogen peroxide (H2O2). Here, a Cu, Zn SOD (WT) from a high altitude plant (Potentilla atrosanguinea) was engineered by substituting a conserved residue proline to glycine at position 61 (P61G). The computational analysis showed higher structural flexibility and clusters in P61G than WT. The P61G exhibited moderately higher catalytic efficiency (Km = 0.029 μM, Vmax = 1488) than WT protein (Km = 0.038 μM, Vmax = 1290.11). P61G showed higher thermostability as revealed from residual activity (72.25% for P61G than 59.31% for WT after heating at 80 °C for 60 min), differential calorimetry scanning and CD-spectroscopic analysis. Interestingly, the P61G mutation also resulted in enhanced tolerance to H2O2 inactivation than WT protein. The finding on enhancing the biophysico-chemical properties by mutating conserved residue could stand as an example to engineer other enzymes. Also, the reported mutant can be exploited in food and pharmaceutical industries.

Muscle mitochondrial catalase expression prevents neuromuscular junction disruption, atrophy, and weakness in a mouse model of accelerated sarcopenia.

BackgroundOxidative stress and damage are associated with a number of ageing phenotypes, including age‐related loss of muscle mass and reduced contractile function (sarcopenia). Our group and others have reported loss of neuromuscular junction (NMJ) integrity and increased denervation as initiating factors in sarcopenia, leading to mitochondrial dysfunction, generation of reactive oxygen species and peroxides, and loss of muscle mass and weakness. Previous studies from our laboratory show that denervation‐induced skeletal muscle mitochondrial peroxide generation is highly correlated to muscle atrophy. Here, we directly test the impact of scavenging muscle mitochondrial hydrogen peroxide on the structure and function of the NMJ and muscle mass and function in a mouse model of denervation‐induced muscle atrophy CuZnSOD (Sod1 −/− mice, Sod1KO).MethodsWhole‐body Sod1KO mice were crossed to mice with increased expression of human catalase (MCAT) targeted specifically to mitochondria in skeletal muscle (mMCAT mice) to determine the impact of reduced hydrogen peroxide levels on key targets of sarcopenia, including mitochondrial function, NMJ structure and function, and indices of muscle mass and function.ResultsFemale adult (~12‐month‐old) Sod1KO mice show a number of sarcopenia‐related phenotypes in skeletal muscle including reduced mitochondrial oxygen consumption and elevated reactive oxygen species generation, fragmentation, and loss of innervated NMJs (P < 0.05), a 30% reduction in muscle mass (P < 0.05), a 36% loss of force generation (P < 0.05), and a loss of exercise capacity (305 vs. 709 m in wild‐type mice, P < 0.05). Muscle from Sod1KO mice also shows a 35% reduction in sarco(endo)plasmic reticulum ATPase activity (P < 0.05), changes in the amount of calcium‐regulating proteins, and altered fibre‐type composition. In contrast, increased catalase expression in the mMCAT × Sod1KO mice completely prevents the mitochondrial and NMJ‐related phenotypes and maintains muscle mass and force generation. The reduction in exercise capacity is also partially inhibited (~35%, P < 0.05), and the loss of fibre cross‐sectional area is inhibited by ~50% (P < 0.05).ConclusionsTogether, these striking findings suggest that scavenging of mitochondrial peroxide generation by mMCAT expression efficiently prevents mitochondrial dysfunction and NMJ disruption associated with denervation‐induced atrophy and weakness, supporting mitochondrial H2O2 as an important effector of NMJ alterations that lead to phenotypes associated with sarcopenia.

Fe(III) superoxide radicals in halloysite nanotubes for visible-light-assisted benzyl alcohol oxidation and oxidative C[sbnd]C coupling of 2-naphthol

Selective oxidation of benzyl alcohols to aldehydes and 2-naphthol to BINOL was achieved by activation of molecular oxygen (O2) and hydrogen peroxide (H2O2) over an iron-oxide catalyst embedded in halloysite nanotube. Electron spin resonance spectroscopy (ESR), Raman and in situ FTIR spectroscopic analysis provided direct evidence for the involvement of superoxide radical bound FeIII species in the oxidation reaction. Both the analysis suggested the end-on binding of superoxide radical with FeIII-centre. The stability of such radical bound FeIII-species in halloysite nanotube was analyzed through density functional theory (DFT) calculations. Results suggested that end-on (η1) binding was favourable by 13.5 kcal/ mol than the side-on (η2) binding mode. The formation of such reactive species was believed to play the crucial role in bringing the high selectivity in the catalytic oxidation of benzyl alcohol and oxidative CC coupling of 2-naphthol. UV–Vis spectroscopic studies on the oxidation of benzyl alcohol suggested for the initial adsorption of substrate molecule on the catalyst surface followed by its interaction with FeIII -superoxide/hydroperoxide species generated upon photoirradiation with visible light in presence of O2. The presence of a suitable band gap ∼2.14 eV enabled the catalyst to catalyze the reaction under visible light irradiation. Both the reactions (benzyl alcohol and 2-naphthol oxidation) were tested in presence of both O2 and H2O2 as oxidants at ambient temperature. The influence of different parameters like rate of oxygen flow, amount of peroxide, nature of solvent, and catalyst amount on the conversion and selectivity of the reactions were studied to understand their role in the catalytic reactions. Successful oxidation of 2-naphthol with H2O2 as oxidant was a real success to overcome the limitations associated with this reaction using H2O2 as oxidant.

Investigation on Potential Efficacy of Methanol Extract of Lawsonia inermis L. against Carbon Tetrachloride Induced Hepatotoxicity in Wistar Albino Rats

Carbon tetrachloride (CCl4) a pharmacological tool was used to induce liver damage in Wistar albino rats. Silymarin (100 mg/kg) and methanol extract of Lawsonia inermis Linn. family Lythraceae (known to possess hepatoprotective compounds) was used to reverse the liver damage caused due to CCl4 (induced toxicity). Hydroalcholic extract of stem bark and leaf of Lawsonia inermis Linn. was evaluated, for its restorative efficacy against CCl4 induced hepatotoxicity which was assessed in terms of biochemical and histopathological parameters. CCl4 produce the altitude levels of serum marker enzymes of alanine aminotransferase (ALT), asparate aminotransferase (AST), alanine phosphatase (ALP) and bilirubin in blood serum. Due to the toxicity of CCl4 cause turbine hepatic cell architecture, necrosis, inflammatory cell infiltration, congestion, and sinusoidal dilatation along with reduction of superoxide dismutase (SOD), catalase, Glutathione-S-transferase (GST) and glutathione peroxidase (GPx) appeared in liver tissue. SOD is the primary step in the defense mechanism involved in the antioxidant system against the oxidative stress. It diminishes by converting the superoxide radical in to peroxide and molecular oxygen. CAT or GPx reactions, also exert a similar effect thereby reducing the level of cellular damage. By oral administration of methanol extract of Lawsonia inermis Linn. plant extracts, i.e., stem bark extract (250 mg/kg b.wt.) and leaf extract (250 mg/kg b. wt.) the levels of these parameters was restored to near controlled (untreated) levels. Thus, the present study revealed that the extracts of stem bark and leaf of Lawsonia inermis Linn. offered protection against hepatotoxicity induced by CCl4.

Expression Profiling of Flavonoid Biosynthesis Genes and Secondary Metabolites Accumulation in Populus under Drought Stress.

Flavonoids are key secondary metabolites that are biologically active and perform diverse functions in plants such as stress defense against abiotic and biotic stress. In addition to its importance, no comprehensive information has been available about the secondary metabolic response of Populus tree, especially the genes that encode key enzymes involved in flavonoid biosynthesis under drought stress. In this study, the quantitative real-time polymerase chain reaction (qRT-PCR) analysis revealed that the expression of flavonoid biosynthesis genes (PtPAL, Pt4-CL, PtCHS, PtFLS-1, PtF3H, PtDFR, and PtANS) gradually increased in the leaves of hybrid poplar (P. tremula × P. alba), corresponding to the drought stress duration. In addition, the activity and capacity of antioxidants have also increased, which is positively correlated with the increment of phenolic, flavonoid, anthocyanin, and carotenoid compounds under drought stress. As the drought stress prolonged, the level of reactive oxygen species such as hydrogen peroxide (H2O2) and singlet oxygen (O2−) too increased. The concentration of phytohormone salicylic acid (SA) also increased significantly in the stressed poplar leaves. Our research concluded that drought stress significantly induced the expression of flavonoid biosynthesis genes in hybrid poplar plants and enhanced the accumulation of phenolic and flavonoid compounds with resilient antioxidant activity.

Modification of Gold Zeolitic Supports for Catalytic Oxidation of Glucose to Gluconic Acid.

Activity of gold supported catalysts strongly depends on the type and composition of support, which determine the size of Au nanoparticles (Au NPs), gold-support interaction influencing gold properties, interaction with the reactants and, in this way, the reaction pathway. The aim of this study was to use two types of zeolites: the three dimensional HBeta and the layered two-dimensional MCM-36 as supports for gold, and modification of their properties towards the achievement of different properties in oxidation of glucose to gluconic acid with molecular oxygen and hydrogen peroxide. Such an approach allowed establishment of relationships between the activity of gold catalysts and different parameters such as Au NPs size, electronic properties of gold, structure and acidity of the supports. The zeolites were modified with (3-aminopropyl)-trimethoxysilane (APMS), which affected the support features and Au NPs properties. Moreover, the modification of the zeolite lattice with boron was applied to change the strength of the zeolite acidity. All modifications resulted in changes in glucose conversion, while maintaining high selectivity to gluconic acid. The most important findings include the differences in the reaction steps limiting the reaction rate depending on the nature of the oxidant applied (oxygen vs. H2O2), the important role of porosity of the zeolite supports, and accumulation of negative charge on Au NPs in catalytic oxidation of glucose.

Seminal Plasma Does Not Influence Canine Semen Stored at 5°C for Long-Term Conservation.

Seminal plasma has several components that protect the sperm cells and assist in the fertilization process. In contrast, the exact role carried out by seminal plasma during the cooling of canine semen remains controversial. Moreover, concerning the long estrus period, the possibility to store chilled semen at 5°C for more than 72 hours and maintain good sperm quality for additional inseminations could increase fertilization rates. Thus, this study aimed to evaluate the seminal plasma influence on quality and oxidative stress of the extended canine semen stored at 5°C for 7 days. Three ejaculate pools from eight healthy dogs were collected by digital manipulation of the penis. The sperm kinetics, sperm vitality (eosin/nigrosin stain), integrity of plasma and acrosomal membranes, morphology, superoxide and hydrogen peroxide production, mitochondrial potential, lipid peroxidation, and oxygen reactive species production (induced and spontaneous thiobarbituric acid [thiobarbituric acid reactive substances, TBARS] assay) were evaluated every 48 hours (M0, M48, M96, and M168) until 7 days (168 hours) in cooled extended (TRIS egg yolk) semen of dogs at 5°C with (+SP) or without (-SP) autologous seminal plasma. No statistical difference was found for sperm kinetics in cooled samples with +SP and -SP during the experimental time period, except for the progressive motility of +SP samples that was higher at M48 than M96 (p = 0.023). The seminal plasma did not influence any other evaluated sperm characteristics. Finally, our results demonstrated that the presence or lack of seminal plasma during cooling the semen of dogs does not influence sperm quality at 5°C. Moreover, the components of the semen extender may contribute to maintaining good sperm quality and low reactive oxygen species production during the long period of the dog's semen cooling, even after semen centrifugation.

High removal efficiency of industrial toxic compounds through stable catalytic reactivity in water treatment system

We identified optimal conditions for the disposal of high concentration of organic contaminants within a short time using a hybrid advanced oxidation process (AOP) combining various oxidizing agents. Plasma-treated water (PTW) containing many active species, that play dominant roles in the degradation of organic substances like hydroxyl radicals, atomic oxygen, ozone, and hydrogen peroxide, was used in this study as a strategy to improve degradation performance without the use of expensive chemical reagents like hydrogen peroxide. In particular, the optimal decomposition conditions using PTW, which were combined with 10 mg/h ozone, 2 g/L iron oxide, and 4 W UV light, demonstrated excellent removal abilities of a high concentration of reactive black 5 (RB5; 100 mg/L, >99%, [k] = 4.15 h−1) and tetracycline (TC; 10 mg/L, >96.5%, [k] = 3.35 h−1) for 25 min, approximately 1.5 times higher than that without PTW (RB5; 100 mg/L, 94%, [k] = 2.80 h−1). These results confirmed that the production of strong reactive hydroxyl radicals from the decomposition process, as well as various reactive species included in PTW efficiently attacked pollutant substances, resulting in a higher removal rate. This suggests that a water treatment system with this optimal condition based on complex AOP systems using PTW could be useful in critical environmental and biomedical applications.

Enhanced electron transfer and hydrogen peroxide activation capacity with N, P-codoped carbon encapsulated CeO2 in heterogeneous electro-Fenton process

Designing catalysts that can effectively activate oxygen and hydrogen peroxide is a huge challenge in electro-Fenton (EF) process. Considering the superior ability of electrons transport and activation of H2O2, ceria encapsulated with N, P-codoped carbon material was a promising catalyst for EF reaction. Herein, CeO2-NPCTX (where T and X represented the calcination temperature and the initial mass of CeO2, respectively) materials were synthesized via pyrolysis process and used as catalysts to degrade ciprofloxacin (CIP) in EF process. The results indicated that CeO2-NPC1000100 catalyst had good degradation performance under the optimal conditions. Compared with CeO2 and CeO2-NC1000100 catalysts, CeO2-NPC1000100 catalyst had more content of graphite N and more oxygen vacancies, which were beneficial to activation of oxygen and hydrogen peroxide. Scavenging experiments and electron paramagnetic resonance analysis confirmed ·O2− and ·OH were the main reactive oxygen species in the CIP degradation process. And three logical degradation routes of CIP were given. In addition, CeO2-NPC1000100 catalyst still had good stability after three times of continuous operation, and presented good universality for the treatment of a variety of antibiotic wastewaters. Finally, a convincing mechanism in the EF system with CeO2-NPC1000100 for CIP degradation was proposed.

Abstract MP234: Novel Mybpc3 Variant Disrupts Myosin S2 Binding And Induces Heart Failure

Rationale: Cardiac m yosin binding protein-C regulates a ctomyosin interaction in striated muscle, but mutations in the MYBPC3 gene can lead to hypertrophic cardiomyopathy (HCM) as seen in some South Asians living in the USA carrying a novel variant wherein an aspartic acid is mutated to a valine at position 389 (D389V). Individuals and iPSC-derived cardiomyocytes carrying D389V display hypercontractility, indicating early onset of HCM. However, the mechanisms underlying the pathophysiology of this mutant in the context of HCM are unknown. Objective: To define the pathophysiological consequences D389V on myosin and cardiac function in vivo . Methods and Results: Compared with wild-type controls, our D389V knock-in homozygous mouse model showed decreased cardiac function by percentage of ejection fraction (-23%, P&lt;0.01), but increased systolic left ventricular volume (+39%, P&lt;0.01) at 3 and 6 months of age. Heart weight to tibia length ratio was significantly increased (+ 15%, P=0.05), demonstrating distinct pathogenicity. Using recombinant proteins carrying D389V substitution at the N-terminal MYBPC3 domains (rC0C2 D389V ), cosedimentation and solid-phase binding assays showed significantly reduced binding rate of rC0C2 D389V to the myosin S2 region (-55% and -23%, P&lt;0.05, respectively), but in vitro actin motility over myosin increased 24% (P&lt;0.05) compared to rC0C2 WT control, indicating a causal relationship between variant and decreased MYBPC3 binding to myosin. Human iPSC-derived D389V het cardiomyocytes display an increase in lipid peroxide and reactive oxygen species by +3- and +7-fold P&lt;0.01, respectively, compared to noncarrier controls. Conclusion: D389V decreases interaction between MYBPC3 and myosin S2, causing reduced cardiac function and providing mechanistic evidence that it contributes to the etiology of HCM.

Combining pieces: a thorough analysis of light activation boosting power and co-substrate preferences for the catalytic efficiency of lytic polysaccharide monooxygenase MtLPMO9A

Cost-efficient plant biomass conversion using biochemical and/or chemical routes is essential for transitioning to sustainable chemical technologies and renewable biofuels. Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes that make part of modern hydrolytic cocktails destined for plant biomass degradation. Here, we characterized MtLPMO9A from Thermothelomyces thermophilus M77 (formerly Myceliophthora thermophila) and demonstrated that it could be efficiently driven by chlorophyllin excited by light in the presence of a reductant agent. However, in the absence of chemical reductant, chlorophyllin and light alone do not lead to a significant release of the reaction products by the LPMO, indicating a low capacity of MtLPMO9A reduction (either via direct electron transfer or via superoxide ion, O2•-). We showed that photocatalysis could significantly increase the LPMO activity against highly crystalline and recalcitrant cellulosic substrates, which are poorly degraded in the absence of chlorophyllin and light. We also evaluated the use of co-substrates by MtLPMO9A, revealing that the enzyme can use both hydrogen peroxide (H2O2) and molecular oxygen (O2) as co-substrates for cellulose catalytic oxidation.

ASSESSMENT OF SUPEROXIDE DISMUTASE, CATALASE, AND PEROXIDASE ACTIVITIES IN ASPERGILLUS SP. AND CLADOSPORIUM SP.

Antioxidative enzymes are a family of powerful free radical scavenging proteins, naturally synthesized by all aerobic organisms. Family of antioxidant enzymes include superoxide dismutase (SOD), catalase (CAT), peroxidase (PRX), thioredoxins /thioredoxin reductase (TrxR), and glutaredoxins/glutathione reductase (GPx). These oxidative enzymatic machineries, sequentially sequester singlet oxygen (O2 −) and Hydrogen Peroxide, which are the well-known reactive oxygen species. These enzymes can be intracellular as well as extracellular. In the present study, two most common soil fungi namely, Aspergillus Sp. and Cladosporium Sp. were cultivated by submerged cultivation on Potato dextrose broth and pellets were separated by filtration. Pellets were disrupted by detergent lysis method (0.5% Triton X 100, 1% CTAB, 1.5% Tween 80, 5% SDS). Culture media and cellular extracts were analyzed for intracellular and extracellular total proteins and their panel of antioxidative enzymes. Enzyme activity of SOD was carried out by Beauchamp and Fridovich method. Catalase and Peroxidase activities were determined by simple spectrophotometric method. In Aspergillus Sp.1.33 U of superoxide dismutase, 0.115 U catalase, 0.00097 U peroxidase activities per mg of protein was observed. Similarly, in Cladosporium Sp. 1.38 U Superoxide dismutase, 0.1460 U catalase, and 0.00150 U peroxidase activities per mg protein was recorded. Significant amount of antioxidative enzyme activity observed in both the test cultures. And comparatively, Cladosporium Sp has given promising results. Probably, with altered culture conditions and improved extraction procedures, still higher amounts of antioxidative enzymes would be expected.

In vitro evaluation of a novel oxygen-generating biomaterial for chronic rhinosinusitis therapy.

Hypoxia due to closure at the ostiomeatal complex is widely considered one of the major pathogenic mechanisms leading to chronic inflammation in chronic rhinosinusitis (CRS). The objective of this study was to develop and characterize an oxygen-generating biomaterial (OGB) as an innovative treatment strategy for CRS. An OGB was fabricated by coating hydrophobic beeswax (BW, 15mg or 30mg) on the surface of calcium peroxide - catalase complex (CPO-CA, 30mg) and characterized using scanning electron microscopy (SEM). In vitro releases of both oxygen and hydrogen peroxide (H2 O2 ) were spectrophotometrically quantified, and cytotoxicity in human sinonasal epithelial cells (HSNECs) was evaluated. The influence of OGB on transepithelial Cl- secretion was also determined by pharmacologically manipulating HSNECs, cultured under hypoxic conditions, in Ussing chambers. Three groups of OGBs: (1) CPO only; (2) CPO coated with CA and BW (1:1 ratio, CPO-CA(1)-BW(1)); and (3) CPO coated with CA and BW (1:0.5 ratio, CPO-CA(1)-BW(0.5) were analyzed for accumulated oxygen release over 7 days: highest release (mmol/mg) was observed in CPO-CA(1)-BW(1)=0.11±0.003, followed by CPO-CA(1)-BW(0.5)=0.08 ± 0.010, and CPO=0.05 ± 0.004 (p<0.0001). H2 O2 production (mM) was significantly higher in CPO (1.87±0.50) compared to CPO-CA (1)-BW(1) (0.00±0.00) (p<0.001) after 24h. CPO-CA(1)-BW(1) showed significantly reduced cytotoxicity and increased Cl- transport compared to the CPO group. A novel OGB (CPO-CA-BW complex) exhibited sustained oxygen release over 7 days without significant cytotoxicity after 24h in vitro. Preclinical studies evaluating the efficacy of OGB in CRS are warranted, especially for potential therapy in an obstruction-based CRS model.

Acid leaching of LiCoO2 enhanced by reducing agent. Model formulation and validation

In this work, a model has been formulated to describe the complex process of LiCoO2 leaching through the participation of competing reactions in acid media including the effect of H2O2 as reducing agent. The model presented here describes the extraction of Li and Co in the presence and absence of H2O2, and it takes into account the different phenomena affecting the controlling mechanisms. In this context, the model predicts the swift from kinetic control to diffusion control. The model has been implemented and solved to simulate the leaching process. To validate the model and to estimate the model parameters, a set of 12 (in triplicate) extraction experiments were carried out varying the concentration of hydrochloric acid (within the range of 0.5–2.5 M) and hydrogen peroxide (range 0–0.6%v/v). The simulation results match fairly well with the experimental data for a wide range of conditions. Furthermore, the model can be used to predict results with different solid-liquid ratios as well as different acid and oxygen peroxide concentrations. This model could be used to design or optimize a LiCoO2 extraction process facilitating the corresponding economical balance of the treatment.

Protective effects of lycopene on mitochondrial oxidative injury and dysfunction in the liver of aflatoxin B1-exposed broilers

This study was conducted to investigate the effects of lycopene (LYC) on mitochondrial oxidative injury and dysfunction in the liver of aflatoxin B1 (AFB1)-exposed broilers. A total of 192 healthy 1-day-old male broilers were randomly divided into 3 groups with 8 replicates of 8 birds each. Birds in the 3 groups were fed basal diet (control), basal diet with 100 µg/kg AFB1, and basal diet with 100 µg/kg AFB1 and 200 mg/kg LYC, respectively. The experiment lasted 42 d. The results showed that AFB1 decreased average daily body weight gain (ADG), average daily feed intake, and gain to feed ratio (G :F) compared to the control group, the LYC supplementation increased ADG and G/F compared to AFB1 group (P < 0.05). Broilers in the AFB1 group had lower mitochondrial glutathione (mGSH) concentration and glutathione peroxidase (GSH-Px), manganese superoxide dismutase (MnSOD), and thioredoxin reductase activities, and higher hydrogen peroxide (H2O2) and reactive oxygen species (ROS) concentrations than the control group (P < 0.05). The LYC increased mGSH concentration and GSH-Px and MnSOD activities, and decreased H2O2 and ROS concentrations compared to AFB1 group (P < 0.05). Broilers fed the AFB1 diet showed increased mitochondrial swelling and decreased adenosine triphosphate concentration than the control group, and LYC had opposite effects (P < 0.05). The AFB1 decreased the activities of mitochondrial electron transfer chain (ETC) complexes I, II, III, and V, downregulated the mRNA expression levels of hepatic MnSOD, thioredoxin 2, thioredoxin reductase, peroxiredoxin-3, peroxisome proliferator-activated receptor γ coactivator 1α, nuclear respiratory factor 1, and mitochondrial transcription factor A compared with the control group (P < 0.05), and LYC increased activities of mitochondrial ETC complexes III and V, and upregulated mRNA expression levels of these genes in comparison to AFB1 group (P < 0.05). In conclusion, the LYC protected broilers from AFB1-induced liver mitochondrial oxidative injury and dysfunction by stimulating mitochondrial antioxidant capacity and maintaining mitochondrial biogenesis.

Reaction frequency of solvated electrons in water interacting with atmospheric-pressure helium plasma jet

We employed the charge transfer to solvent (CTTS) transition of iodine negative ions to investigate the reactivity of solvated electrons in water interacting with an atmospheric-pressure helium plasma jet. A dye laser pulse at 225 nm was injected into the solution of potassium iodide, which was irradiated with an atmospheric-pressure helium plasma jet, and the reaction frequency of solvated electrons produced by the CTTS transition was measured by optical absorption spectroscopy. We observed the temporal and spatial variations of the reaction frequency of solvated electrons. We found that the reaction frequency of solvated electrons was determined by the concentrations of dissolved oxygen and hydrogen peroxide. We detected a high reaction frequency of solvated electrons in the limited depth region from the solution surface, indicating that hydrogen peroxide is localized near the plasma-liquid interface.

Valorization of Small Alkanes by Biocatalytic Oxyfunctionalization.

The oxidation of alkanes into valuable chemical products is a vital reaction in organic synthesis. This reaction, however, is challenging, owing to the inertness of C-H bonds. Transition metal catalysts for C-H functionalization are frequently explored. Despite chemical alternatives, nature has also evolved powerful oxidative enzymes (e. g., methane monooxygenases, cytochrome P450 oxygenases, peroxygenases) that are capable of transforming C-H bonds under very mild conditions, with only the use of molecular oxygen or hydrogen peroxide as electron acceptors. Although progress in alkane oxidation has been reviewed extensively, little attention has been paid to small alkane oxidation. The latter holds great potential for the manufacture of chemicals. This Minireview provides a concise overview of the most relevant enzyme classes capable of small alkanes (C<6 ) oxyfunctionalization, describes the essentials of the catalytic mechanisms, and critically outlines the current state-of-the-art in preparative applications.

Detection of Oxidative Stress Induced by Nanomaterials in Cells-The Roles of Reactive Oxygen Species and Glutathione.

The potential of nanomaterials use is huge, especially in fields such as medicine or industry. Due to widespread use of nanomaterials, their cytotoxicity and involvement in cellular pathways ought to be evaluated in detail. Nanomaterials can induce the production of a number of substances in cells, including reactive oxygen species (ROS), participating in physiological and pathological cellular processes. These highly reactive substances include: superoxide, singlet oxygen, hydroxyl radical, and hydrogen peroxide. For overall assessment, there are a number of fluorescent probes in particular that are very specific and selective for given ROS. In addition, due to the involvement of ROS in a number of cellular signaling pathways, understanding the principle of ROS production induced by nanomaterials is very important. For defense, the cells have a number of reparative and especially antioxidant mechanisms. One of the most potent antioxidants is a tripeptide glutathione. Thus, the glutathione depletion can be a characteristic manifestation of harmful effects caused by the prooxidative-acting of nanomaterials in cells. For these reasons, here we would like to provide a review on the current knowledge of ROS-mediated cellular nanotoxicity manifesting as glutathione depletion, including an overview of approaches for the detection of ROS levels in cells.

Clinical Attestation and Redox Mechanism of Ascorbic Acid in the Treatment of Cancer

Ascorbic acid (Vitamin C) is an essential micro-nutrient, an outstanding antioxidant and an essential co-factor in different mammalian enzymatic processes. There is considerable clinical attestation that, high dose of intravenous ascorbic acid can improve cancer patients with or without extant therapeutic involvements. Ascorbic acid in high intravenous doses serves as pro-oxidant and promotes the generation of hydrogen peroxide (H2O2) and other reactive oxygen species (ROS) with oxidative stress-induced toxicity selectively to cancer cells. This effect also hampers the bioenergetics and angiogenesis of malignant cells, resulting in cancer cell death. Large doses of ascorbic acid are safe and well-tolerated. On account of its antioxidant effect, ascorbic acid supplementation may be applied as an adjuvant with regular cancer therapy to minimize complications. Nevertheless, there is a necessity for further mechanistic studies and randomized controlled clinical trials to evaluate the benefit of ascorbic acid in the treatment of cancer.