Oxygen-centered Free Radicals Research Articles

Evaluating Possible Formation Mechanisms of Criegee Intermediates during the Heterogeneous Autoxidation of Squalene.

Organic molecules in the environment oxidatively degrade by a variety of free radical, microbial, and biogeochemical pathways. A significant pathway is heterogeneous autoxidation, in which degradation occurs via a network of carbon and oxygen centered free radicals. Recently, we found evidence for a new heterogeneous autoxidation mechanism of squalene that is initiated by hydroxyl (OH) radical addition to a carbon-carbon double bond and apparently propagated through pathways involving Criegee Intermediates (CI) produced from β-hydroxy peroxy radicals (β-OH-RO2•). It remains unclear, however, exactly how CI are formed from β-OH-RO2•, which could occur by a unimolecular or bimolecular pathway. Combining kinetic models and multiphase OH oxidation measurements of squalene, we evaluate the kinetic viability of three mechanistic scenarios. Scenario 1 assumes that CI are formed by the unimolecular bond scission of β-OH-RO2•, whereas Scenarios 2 and 3 test bimolecular pathways of β-OH-RO2• to yield CI. Scenario 1 best replicates the entire experimental data set, which includes effective uptake coefficients vs [OH] as well as the formation kinetics of the major products (i.e., aldehydes and secondary ozonides). Although the unimolecular pathway appears to be kinetically viable, future high-level theory is needed to fully explain the mechanistic relationship between CI and β-OH-RO2• in the condensed phase.

Relating Paramagnetic Properties to Molecular Parameters of Humic Acids Isolated from Permafrost Peatlands in the European Arctic.

Free radicals (FRs) are intermediate participants in the transformation process of soil organic matter, and free radical activity is a fundamental property of humic substances. The aim of this work was to conduct a comparative study of the paramagnetic properties of humic acids (HAs) isolated from Histosols by electron paramagnetic resonance (EPR) spectroscopy. The studied Histosols are found in permafrost peatlands in four natural geographic subzones of the European Arctic (from forest tundra to northern tundra). The results obtained showed that in anaerobic conditions on the peatlands in the tundra zone, the formation of semiquinone-type radicals occurs through the reduction of quinone fragments of HAs and leads to an increase in the concentration of paramagnetic centres within HAs. PCA analysis allowed us to reveal relationships between the properties of the initial raw peat samples, the molecular composition of the isolated HAs, and their paramagnetic parameters. It was found that FR localization occurs predominantly on aromatic fragments of lignin nature, which are confined to the low molecular weight fraction of HAs. The g-factor values of the EPR spectra of HAs indicate the presence of carbon- and oxygen-centred FRs in the HA structure, with a predominance of the latter.

Novel electrochemiluminescence aptasensor based on AuNPs-ABEI encapsulated TiO2 nanorod for the detection of acetamiprid residues in vegetables

Gold nanoparticles (AuNPs)@N-(4-aminobutyl)-N-ethylisoluminol (ABEI)@Titanium dioxide nanorods (TiO2NRs) were used as sensing materials to produce a unique encapsulated nanostructure aptasensor for the detection of acetamiprid residues in this work. ABEI, an analog of luminol, was extensively used as an electrochemiluminescence (ECL) reagent. The ECL mechanism of ABEI- hydrogen peroxide (H2O2) system had connections to a number of oxygen-centered free radicals. TiO2NRs improved ECL response with high electron transfer and a specific surface area. AuNPs were easy to biolabel and could catalyze H2O2 to enhance ECL signal. AuNPs were wrapped around TiO2NRs by utilizing the reduction property of ABEI to form wrapped modified nanomaterials. The sulfhydryl-modified aptamer bound to the nanomaterial by forming gold-sulfur (Au–S) bonds. The aptamer selectively bound to its target with the addition of acetamiprid, which caused a considerable decrease in ECL intensity and enabled quantitative detection of acetamiprid. The aptasensor showed good stability, repeatability and specificity with a broad detection range (1×10−2-1×103 nM) and a lower limit of detection (3 pM) for acetamiprid residues in vegetables. Overall, this aptasensor presents a simple and highly sensitive method for ECL detecting acetamiprid, with potential applications in vegetable safety monitoring.

Comparative 6+studies of environmentally persistent free radicals on nano-sized coal dusts

Coal dust is the major hazardous pollutant in the coal mining environment. Recently environmentally persistent free radicals (EPFRs) were identified as one of the key characteristics which could impart toxicity to the particulates released into the environment. The present study used Electron Paramagnetic Resonance (EPR) spectroscopy to analyze the characteristics of EPFRs present in different types of nano-size coal dust. Further, it analyzed the stability of the free radicals in the respirable nano-size coal dust and compared their characteristics in terms of EPR parameters (spin counts and g-values). It was found that free radicals in coal are remarkably stable (can remain intact for several months). Also, Most of the EPFRs in the coal dust particles are either oxygenated carbon centered or a mixture of carbon and oxygen-centered free radicals. EPFRs concentration in the coal dust was found to be proportional to the carbon content of coal. The characteristic g-values were found to be inversely related to the carbon content of coal dust. The spin concentrations in the lignite coal dust were between 3.819 and 7.089 μmol/g, whereas the g-values ranged from 2.00352 to 2.00363. The spin concentrations in the bituminous coal dust were between 11.614 and 25.562 μmol/g, whereas the g-values ranged from 2.00295 to 2.00319. The characteristics of EPFRs present in coal dust identified by this study are similar to the EPFRs, which were found in other environmental pollutants such as combustion-generated particulates, PM2.5, indoor dust, wildfires, biochar, haze etc., in some of the previous studies. Considering the toxicity analysis of environmental particulates containing EPFRs similar to those identified in the present study, it can be confidently hypothesized that the EPFRs in the coal dust might play a major role in modulating the coal dust toxicity. Hence, it is recommended that future studies should analyze the role of EPFR-loaded coal dust in mediating the inhalation toxicity of coal dust.

Molecular characteristics of microalgal extracellular polymeric substances were different among phyla and correlated with the extracellular persistent free radicals

Extracellular polymeric substance (EPS) plays essential roles in microalgal adaptation to the external environment and aggregate formation. The molecular characteristics of EPS and extracellular persistent free radicals (PFRs) of 15 microalgal species belonging to three phyla were analyzed using Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), three-dimensional fluorescence excitation-emission matrices combined with parallel factor analysis (EEM-PARAFAC), and Electron Paramagnetic Resonance Spectrometer (EPR). Lignin accounted for the highest proportion of EPS for Cyanophyta and the proportion of lipids was higher for Bacillariophyta. The presence of PFRs was detected on the cell surfaces of all microalgae species (excluding Cyclotella sp.). The intensity of carbon-centered PFRs was positively correlated with the proportions of humic-like component and lignin, but was negatively correlated with the proportion of lipids in microalgal EPS. Following EPS extraction, carbon- and oxygen-centered free radicals were still detectable on the surface of microalgae. Given the high intensity of PFRs produced by Cyanophyta, the level of PFRs in eutrophic lakes and reservoirs predominated by Cyanophyta may be considerably high. Other organisms in the water column, such as bacteria and zooplankton are bound to be stressed by elevated level of PFRs. The ecological functions and environmental risks of PFRs carried by microalgae still need to be explored in follow-up research.

Effect of controlled temperature and biomass addition on the formed environmental persistent free radicals (EPFRs) in sewage sludge-based biochar from pyrolysis treatment

Sludge-based biochar derived from pyrolysis treatment is often utilized into soil agricultural fertilizer and soil amendment. While recent studies found that a new class of emerging environmental pollutant, environmental persistent free radicals (EPFRs) could be produced in combustion-based particles and airborne particulate matter. This study was aimed to determine if similar radicals were present in biochar derived from the pyrolyzed organic solid waste. The formation of EPFRs in sludge-based biochar during the pyrolysis treatment were in detailed characterized. EPFRs in biochar derived from sewage sludge pyrolysis at 200–600 ℃ and with various biomass addition were identified by using Electron paramagnetic resonance spectrometer. Three types of EPFRs were mainly spotted in the obtained biochar, including oxygen-centered, carbon-centered and F-centered radicals. Results revealed that the spin concentration of EPFRs decreased with temperature, and an increasing pyrolysis temperature could inhibit the formation of EPFRs. Lower pyrolysis temperature (＜400 ℃) favored the production of carbon-centered radicals, whereas higher temperature (＞400 ℃) mainly produced oxygen-centered radicals. Adding biomass also significantly affected the spin concentration and types of EPFRs. The spin concentration of EPFRs reached the highest value when adding 50% of biomass. The g-values of EPFRs in biochar were all less than 2.0030, indicating that carbon-centered and F-centered free radicals had occupied the dominance. In addition, the determination on the half-lives of EPFRs indicated that carbon-centered EPFRs were almost transformed to oxygen-centered EPFRs with storage time increased. The oxygen-centered free radicals became the dominant type of EPFRs after 100 days and even 200 days storage. The obtained findings imply the ecotoxicity of sludge-based biochar and give in-depth insight on the formation EPFRs, thus guiding the innocuous utilization of sludge.

Adsorption and catalytic degradation of preservative parabens by graphene-family nanomaterials

Parabens pose increasing threats to human health due to endocrine disruption activity. Adsorption and degradation of parabens by three types of graphene-family nanomaterials (GFNs) were therefore investigated. For a given paraben, the maximum adsorption capacities (Q0) followed the order of reduced graphene oxide (RGO) > multilayered graphene (MG) > graphene oxide (GO); for a given GFN, Q0 followed the order of butylparaben (BuP) > propylparaben (PrP) > ethylparaben (EtP) > methylparaben (MeP), dominated by hydrophobic interaction. MeP removal by all the three GFNs was highly enhanced (0.55–4.37 times) with the assistance of H2O2 due to additional catalytic degradation process, and MG showed the highest removal enhancement. ∙OH was confirmed as the dominant radicals responsible for parabens degradation. For MG and RGO, the metal impurities (Fe, Cu, Mn, and Co) initiated Fenton-like reaction with H2O2 to generate ∙OH. GO contained oxygen-centered free radicals, which were responsible for ∙OH formation via transferring electron to H2O2. Four degradation byproducts of MeP were identified, including oxalic, propanedioic, fumaric, and 2,5-dihydroxybenzoic acids. Combined with density function theory calculations, the degradation sites and pathways were identified and confirmed. These findings provide useful information on mechanistic understanding towards the adsorption and degradation of parabens by GFNs.

Reactive Sterol Electrophiles: Mechanisms of Formation and Reactions with Proteins and Amino Acid Nucleophiles.

Radical-mediated lipid oxidation and the formation of lipid hydroperoxides has been a focal point in the investigation of a number of human pathologies. Lipid peroxidation has long been linked to the inflammatory response and more recently, has been identified as the central tenet of the oxidative cell death mechanism known as ferroptosis. The formation of lipid electrophile-protein adducts has been associated with many of the disorders that involve perturbations of the cellular redox status, but the identities of adducted proteins and the effects of adduction on protein function are mostly unknown. Both cholesterol and 7-dehydrocholesterol (7-DHC), which is the immediate biosynthetic precursor to cholesterol, are oxidizable by species such as ozone and oxygen-centered free radicals. Product mixtures from radical chain processes are particularly complex, with recent studies having expanded the sets of electrophilic compounds formed. Here, we describe recent developments related to the formation of sterol-derived electrophiles and the adduction of these electrophiles to proteins. A framework for understanding sterol peroxidation mechanisms, which has significantly advanced in recent years, as well as the methods for the study of sterol electrophile-protein adduction, are presented in this review.

Free radical scavenging mechanism of 1,3,4-oxadiazole derivatives: thermodynamics of O–H and N–H bond cleavage

The thermodynamics of free radical scavenge of 1,3,4-oxadiazole derivatives towards oxygen-centred free radicals were investigated by the density functional theory (DFT) method in the gas phase and aqueous solution. Three mechanisms of free radical scavenge namely, hydrogen atom transfer (HAT), single electron transfer followed by proton transfer (SET-PT) and sequential proton loss electron transfer (SPLET) were considered. The antioxidant descriptors that characterize these mechanisms such as, bond dissociation enthalpy (BDE), adiabatic ionization potential (AIP), proton dissociation enthalpy (PDE), proton affinity (PA) and electron transfer enthalpy (ETE) were evaluated. The sequence of electron donation as predicted by the HOMO results were in good agreement with the sequence of ETE for the considered molecules at their favoured sites of free radical scavenge. The reaction Gibbs free energy for inactivation of the selected peroxyl radicals, show that 1,3,4-oxadiazole antioxidants are more efficient radical scavengers by HAT and SPLET mechanisms than SET-PT mechanism in vacuum. In aqueous solution, the SET-PT mechanism was observed to be the dominant reaction pathway.

Formation and Evolution of Solvent-Extracted and Nonextractable Environmentally Persistent Free Radicals in Fly Ash of Municipal Solid Waste Incinerators.

Environmentally persistent free radicals (EPFRs) are emerging contaminants occurring in combustion-borne particulates and atmospheric particulate matter, but information on their formation and behavior on fly ash from municipal solid waste (MSW) incinerators is scarce. Here, we have found that MSW-associated fly ash samples contain an EPFR concentration of 3-10 × 1015 spins g-1, a line width (ΔHp-p) of ∼8.6 G, and a g-factor of 2.0032-2.0038. These EPFRs are proposed to be mixtures of carbon-centered and oxygen-centered free radicals. Fractionation of the fly ash-associated EPFRs into solvent-extracted and nonextractable radicals suggests that the solvent-extracted part accounts for ∼45-73% of the total amount of EPFRs. Spin densities of solvent-extracted EPFRs correlate positively with the concentrations of Fe, Cu, Mn, Ti, and Zn, whereas similar correlations are comparatively insignificant for nonextractable EPFRs. Under natural conditions, these two types of EPFRs exhibit different stabilization that solvent-extracted EPFRs are relatively unstable, whereas the nonextractable fraction possesses a long life span. Significant correlations between concentrations of solvent-extracted EPFRs and generation of hydroxyl and superoxide radicals are found. Overall, our results suggest that the fractionated solvent-extracted and nonextractable EPFRs may experience different formation and stabilization processes and health effects.

20 The polyphenol delphinidin induces antioxidant effects in human umbilical vein endothelial cells through activation of endogenous glutathione: importance of using relevant concentration in in vitro systems

Polyphenols are regarded to have a wide range of health-promoting effects. Increased consumption of polyphenol-rich food is known to be associated with numerous cardioprotective effects. Polyphenols have been shown to improve endothelial function, inhibit abnormal platelet aggregation, reduce inflammation and improve plasma lipid profiles. Moreover, polyphenols have been widely recognised as powerful antioxidants. Given that oxidative stress plays a key role in initiation and progression of atherosclerosis, antioxidant therapy with polyphenols has potential. However, the concentrations required to mediate sufficient antioxidant effect appear to be unattainable under in vivo conditions. Polyphenols are characterised by poor absorption, rapid degradation and extensive metabolism, culminating in poor bioavailability (~1 µM). In addition, they can also exhibit paradoxical pro-oxidant activities. Spectrophotometric and mass spectrometry (LC-MS/MS) analysis of the phenolic compound, delphinidin, confirmed its low stability and rapid degradation (t 1 / 2 ~30 min) under physiologically relevant conditions. Delphinidin degraded to smaller phenolics: gallic acid and phloroglucinol aldehyde. Moreover, both the parent compound and its main metabolite, gallic acid, generated oxygen-centred free radicals at concentrations≥10 µM, as determined by electron paramagnetic resonance spectrometry (EPR). Interestingly, the tested phenolics offered significant protection to human umbilical endothelial cells (HUVECs) against chemically induced oxidative stress. The protective effect of both phenolics were hormesic in profile; supraphysiological concentrations (100 µM) were cytotoxic, whereas physiologically relevant concentrations (100 nM – 1 µM) were protective against oxidative stress. The observed protection was associated with increased intracellular glutathione. The results confirm that physiologically relevant concentrations of delphinidin and its major metabolite, gallic acid, are sufficient to induce antioxidant benefits, but via an indirect, xenobiotic mechanism that induces upregulation of endogenous antioxidant capacity. The findings emphasis that stability, rate of absorption, distribution and metabolism of phenolic compound needs to be taken into consideration when designing in vitro studies to test their mechanism of action.

Sulfite triggers sustained calcium overload in cultured cortical neurons via a redox-dependent mechanism.

Sulfite is a compound commonly used as preservative in foods and pharmaceuticals. Many studies have examined the neurotoxicity of sulfite, but its effect on neuronal calcium homeostasis has not yet been reported. Here, we observed the effect of sulfite on the cytosolic free calcium concentration ([Ca(2+)]i) in cultured cortical neurons using Fura-2/AM based calcium imaging technique. Sulfite (250-1000μM) caused a sustained increase in [Ca(2+)]i in the neurons via a dose-dependent manner. In Ca(2+)-free solution, sulfite failed to increase [Ca(2+)]i. After the depletion of the intracellular calcium store, the effect of sulfite on the [Ca(2+)]i was largely abolished. Pharmacological inhibition of phospholipase C (PLC)-inositol 1,4,5-triphosphate (IP3) signaling pathway blocked sulfite-induced increase of [Ca(2+)]i. Interestingly, antioxidants such as trolox and dithiothreitol, abolished the increase of [Ca(2+)]i induced by sulfite. Exposure to sulfite triggered generation of sulfur- and oxygen-centered free radicals in neurons and increased oxidative stress both in the cultured cortical neurons and the prefrontal cortex of rats. Furthemore, sulfite decreased cell viability in cultured cortical neurons via a calcium-dependent manner. Thus, our current study suggests that the redox-dependent calcium overload triggered by sulfite in cortical neuronsmay be involved in its neurotoxicity.

Catechol degradation on hematite/silica-gas interface as affected by gas composition and the formation of environmentally persistent free radicals.

Environmentally persistent free radicals (EPFRs) formed on a solid particle surface have received increasing attention because of their toxic effects. However, organic chemical fate regulated by EPFRs has rarely been investigated, and this information may provide the missing link in understanding their environmental behavior. Previous studies have suggested that the reduction of transition metals is involved in EPFRs formation. We thus hypothesize that an oxidative environment may inhibit EPFRs formation in particle-gas interface, which will consequently release free radicals and accelerate organic chemical degradation. Our result indicates that a 1% hematite coating on a silica surface inhibited catechol degradation in N2, especially at low catechol loadings on solid particles (SCT). However, under an O2 environment, catechol degradation decreased when SCT was <1 μg/mg but increased when SCT was >1 μg/mg. Stable organic free radicals were observed in the N2 system with g factors in the 2.0035–2.0050 range, suggesting the dominance of oxygen-centered free radicals. The introduction of O2 into the catechol degradation system substantially decreased the free radical signals and decreased the Fe(II) content. These results were observed in both dark and light irradiation systems, indicating the ubiquitous presence of EPFRs in regulating the fate of organic chemicals.

Ultraviolet-B radiation applied to detached peach fruit: A study of free radical generation by EPR spin trapping

In peaches, phenolic compounds are the major sources of antioxidants, and cyanidin-3-O-glucoside is the main anthocyanin present, above all in the skin. Anthocyanin content has been shown to increase after UV-B irradiation, which may be very harmful for all biological organisms due to the induction of the generation of reactive oxygen species (ROS). Peach fruits (cv. ‘Suncrest’) were exposed during post-harvest to supplemental ultraviolet-B radiation. A spin-trapping technique was used to monitor the generation of free radicals under UV-B, and 5-(diethoxy-phosphoryl)-5-methyl-1-pyrroline-N-oxide (DEPMPO) was used as the spin trap. The flesh of peaches was essentially unaffected by the treatment, whereas the skin was responsive at the end of the treatment, accumulating ascorbate, flavonoids, cyanidin-3-O-glucoside, and showing a higher antioxidant activity. The levels of stable free radicals were also lower at the end of treatment. Carbon-centred radicals contributed the most to the total amounts of free radicals, whereas hydroxyl radicals and oxygen-centred free radicals contributed minimally. The carbon-centred free radical identified was the same as the one obtained after irradiation of authentic cyanidin-3-O-glucoside. During UV-B treatment cyanidin-3-O-glucoside increased and was capable of radicalization protecting the other organic molecules of the cell from oxidation. ROS, among which hydroxyl radicals, were thus maintained to minimal levels. This ability of cyanidin-3-O-glucoside displayed the mechanism underlined the tolerance to UV-B irradiation indicating that shelf life can be prolonged by the presence of anthocyanins. Thus, UV-B technique results a good approach to induce antioxidant production in peach fruits increasing their nutraceutical properties.

The Effect of Hydroxycinnamic Acids on Oxy-Radical Generating Iodide–Hydrogen Peroxide Reaction

Abstract The influence of hydroxycinnamic acids (HCA) on the oxy-radical generated system, potassium iodide/hydrogen peroxide, was investigated through the enhancement of triiodide (I3−) yield. Caffeic acid, chlorogenic acid, and p-coumaric acid were used as typical representatives of HCA. A linear correlation, with positive slopes, was found between absorption maximum of I3− at 351 nm and HCA concentration in all cases. The magnitude of enhanced I3− production was found to increase in the following order: p-coumaric acid &amp;lt; chlorogenic acid ≤ caffeic acid. A reaction mechanism, which includes negative influence of oxygen-centered free radicals on the I3− yield, was proposed. The enhanced production of I3− by HCA is attributed to their radical scavenging activity. Supported by literature data, results obtained in this study have showed the correlation between radical scavenging activities of HCA and their ability to enhanced I3− generation.

Covalent modification of carbon surfaces with cyclodextrins by mediated oxidation of β-cyclodextrin monoanions

The covalent grafting of glassy carbon and highly oriented pyrolytic graphite with cyclodextrins is reported in this work. The modification procedure is based in the concept that oxidation of organic anions generates radicals which react with carbon surfaces. These radical species are generated through a redox catalysis mechanism involving the formation of ferrocenium ion, which in turn oxidizes the cyclodextrin monoanion to afford an oxygen-centered free radical that ultimately reacts either in solution or with the surface, affording a strong attachment of cyclodextrin molecules to the carbon surface. The intervention of this radical was established from spectroelectrochemical EPR experiments. Atomic force microscopy imaging showed that the attached organic layer is thick while cyclic voltammetry experiments confirmed that this modified surface behaves as an ultramicroelectrode array. This kind of modification allows incorporate cyclodextrin to an electrode surface without a binder, making the modified electrode useful to be tested in forthcoming sensor studies.

Chemical Constituents from the Branches of Carpinus turczaninowii with Antioxidative Activities

Korean hornbeam Carpinus turczaninowii is a deciduous woody plant belonging to the family Betulaceae. This flora is endemic to Korea, and can reach a height of 15 m. In the autumn, the fallen leaves of C. turczaninowii display a beautiful orange-red color and the tree is commonly used for bonsai in Korea. The wood is very hard, dense and fine textured, and has been used for making agricultural tools and furniture. Previous chemical investigation on this plant indicated only the existence of flavonoids such as naringenin and quercetin glycosides from the leaves. 1 We have recently reported the isolation diarylheptanoids possessing anti-inflammatory activities from the ethanol extract of C. turczaninowii. 2 Reactive oxygen species (ROS) are chemically reactive substances which can attack biomolecules, lipids, proteins and nucleic acid within living organisms. ROS can be classified into two groups: oxygen-centered free radicals (O2 ·� , HO·, RO· and ROO·), and non-radical molecules ( 1 O2 and H2O2). It is known that the formation of ROS is the normal metabolic processes. 3 However, produced in excess or in certain physiological conditions, the generated ROS can cause destructive and harmful effects to human tissues, causing various diseases which are mainly associated with aging. 4 Humans have evolved defense systems which employ antioxidative enzymes to prevent detrimental oxidation. Along with this endogenous protective mechanism, it is believed that exogenous antioxidants are necessary to decrease the cumulative effects of ROS-related damage. Important antioxidants in diet include vitamins and flavonoids from plant sources. Antioxidants are also utilized in the food and cosmetic industries in order to protect from damages associated with ROS. Due to their beneficial effects in broad areas, novel antioxidative agents especially from natural sources have attracted much attention in terms of their ecologically friendly properties. 5 We are continuously conducting research projects to find biologically active natural products from plants growing in Jeju Island, a place of great biodiversity located at the southernmost part of Korea. 6 During our investigation, we observed that the ethanol extract prepared from the branches of C. turczaninowii exhibited significant DPPH radical scavenging activities. Therefore, we decided to carry out a full phytochemical investigation of the extract to determine the bioactive metabolites. We herein described the isolation and structure determination of the chemical constituents. In addition, antioxidative properties for the isolates were examined using the DPPH and ABTS + radical scavenging activity tests.

Antioxidant capacity and total phenolic content of Stachys aucheri endemic plant to Persia

Oxidation is essential to many living organisms for the production of energy to fuel biological processes. However, oxygen-centered free radicals and other reactive oxygen species (ROS), which are continuously, produced in vivo, result in cell death and tissue damage. Anti-oxidants are vital substances which possess the ability to protect the body from damage caused by free radical induced oxidative stress 1. Hence, compounds especially from natural sources capable of protecting against ROS mediated damage may have potential application in prevention and/or curing of diseases. The phenolic compounds in herbs act as antioxidants due to their redox properties. According to the studiese about antioxidant capacity of others species of Stachys, Stachys aucheri Benth. that has not yet been studied was choosed. Total extract of aerial parts was tested by FRAP (ferric reducing antioxidant power) and DPPH2 (1,1-diphenyl -2-picrylhydrazyl) methods. Quantitation of total phenolic content, Folin Ciocalteu method was used. DPPH IC50 (an antioxidant concentration which is capable to inhibit 50% of generated DPPH free radicals) in DPPH method and, EC1 (antioxidant concentration which can change the absorption equal to one mM of Fe2+) in FRAP method and, Total phenolic (equal mg gallic acid) per 100g herb were used for expression of the results. IC50 of hydroalcoholic extract was1.20mg/ml and EC1, was 14.21 mmol Fe 2+ equal per 100g of herb powder. Results show that this plant is good antioxidant candidate to be used in Food industry and as neutriceutical.

Exercise‐induced lipid peroxidation: Implications for deoxyribonucleic acid damage and systemic free radical generation

Exercise-induced deoxyribonucleic acid (DNA) damage is often associated with an increase in free radicals; however, there is a lack of evidence examining the two in parallel. This study tested the hypothesis that high-intensity exercise has the ability to produce free radicals that may be capable of causing DNA damage. Twelve apparently healthy male subjects (age: 23 ± 4 years; stature: 181 ± 8 cm; body mass: 80 ± 9 kg; and VO(2max) : 49 ± 5 ml/kg/min) performed three 5 min consecutive and incremental stages (40, 70, and 100% of VO(2max) ) of aerobic exercise with a 15-min period separating each stage. Blood was drawn after each bout of exercise for the determination of ex vivo free radicals, DNA damage, protein carbonyls, lipid hydroperoxide (LOOH) concentration, and a range of lipid-soluble antioxidants. Lipid-derived oxygen-centered free radicals (hyperfine coupling constants a(Nitrogen) = 13.7 Gauss (G) and aβ(Hydrogen) = 1.8 G) increased as a result of acute moderate and high-intensity exercise (P < 0.05), while DNA damage was also increased (P < 0.05). Systemic changes were observed in LOOH and for lipid-soluble antioxidants throughout exercise (P < 0.05); however, there was no observed change in protein carbonyl concentration (P > 0.05). These findings identify lipid-derived free radical species as possible contributors to peripheral mononuclear cell DNA damage in the human exercising model. This damage occurs in the presence of lipid oxidation but in the absence of any change to protein carbonyl concentration. The significance of these findings may have relevance in terms of immune function, the aging process, and the pathology of carcinogenesis.

Preservation of primary stable isotope signatures of peat-forming plants during early decomposition — observation along an altitudinal transect

The preservation of the primary stable isotope compositions of peat-forming plants in peat was tested along a short (< 3.5 km), steep (739–1393 m asl) altitudinal transect. The stable isotope compositions in plant cube samples taken from the surface of mires were compared with the stable isotope compositions in cube samples of the underlying young peat for the following elements: hydrogen, carbon, nitrogen, oxygen and sulfur (HCNOS). Electron paramagnetic resonance (EPR) measurements were also compared. Statistically significant correlations (p ≤ 0.03) for the pairs of plant-peat samples among all analyzed elements suggested that the stable isotope compositions of peat are primarily determined by the stable isotope compositions of the peat-forming plants. This implies that preservation of the plants' primary stable isotope variations (e.g., from the time of plant growth) is well preserved in young peat and that the overall decomposition during peat formation has only a secondary influence on the final peat stable isotope composition. We were able to detect relative variations in stable isotope composition between plants growing in different conditions and/or at different times. The EPR results confirmed the more anoxic conditions of decomposition at lower altitudes and more oxic conditions at higher altitudes, which involved an increase in oxygen centered free radicals. The observed correlations between the stable isotope compositions of plants and altitude indicated that the δ 13C value of peat-forming plants is primarily controlled by growing season temperature, while the δ 2H and δ 18O values are controlled by stable isotope composition of surface water. The δ 15N and δ 34S values appear to reflect different distributions and concentrations of anthropogenic pollution at the sites of peat-forming plant growth. A strong and statistically significant correlation between altitude/temperature and δ 13C of plants and peats indicates a good preservation of primary stable carbon isotope composition. Thus, the analysis of peat stable isotope compositions could be useful for paleoclimate and paleoenvironmental evaluations.