Fenton Reaction System Research Articles

Fluorometric determination of hydrogen peroxide in milk by using a Fenton reaction system

A simple and highly sensitive fluorometric method is proposed for the determination of H 2O 2 in milk samples. In this method, non-fluorescent coumarin is oxidised to highly fluorescent 7-hydroxycoumarin by hydroxyl radicals ( OH) generated in a Fenton reaction, and the oxidation product has strong fluorescence with a maximum intensity at 456 nm and can be used as a fluorescence probe for H 2O 2. Under the optimal conditions (2.5 × 10 −4 mol L −1 iron(II) ions, 4.0 × 10 −4 mol L −1 coumarin, solution pH 3.0, reaction time 9 min, and excitation at 346 nm), the proposed method presents wide linear responses between the fluorescence intensity and H 2O 2 concentration in a wide range from 2.0 × 10 −8 to 2.0 × 10 −5 mol L −1, with a detection limit ( S/ N = 3) of 5.0 × 10 −9 mol L −1. After possible interferences are evaluated for a series of chemical substances, the present method has been applied to the determination of hydrogen peroxide in milk with satisfactory results.

Biomimetic oxidative treatment of spruce wood studied by pyrolysis–molecular beam mass spectrometry coupled with multivariate analysis and 13C-labeled tetramethylammonium hydroxide thermochemolysis: implications for fungal degradation of wood

In this work, pyrolysis-molecular beam mass spectrometry analysis coupled with principal components analysis and (13)C-labeled tetramethylammonium hydroxide thermochemolysis were used to study lignin oxidation, depolymerization, and demethylation of spruce wood treated by biomimetic oxidative systems. Neat Fenton and chelator-mediated Fenton reaction (CMFR) systems as well as cellulosic enzyme treatments were used to mimic the nonenzymatic process involved in wood brown-rot biodegradation. The results suggest that compared with enzymatic processes, Fenton-based treatment more readily opens the structure of the lignocellulosic matrix, freeing cellulose fibrils from the matrix. The results demonstrate that, under the current treatment conditions, Fenton and CMFR treatment cause limited demethoxylation of lignin in the insoluble wood residue. However, analysis of a water-extractable fraction revealed considerable soluble lignin residue structures that had undergone side chain oxidation as well as demethoxylation upon CMFR treatment. This research has implications for our understanding of nonenzymatic degradation of wood and the diffusion of CMFR agents in the wood cell wall during fungal degradation processes.

Absolute configuration of ceriporic acids, the iron redox-silencing metabolites produced by a selective lignin-degrading fungus, Ceriporiopsis subvermispora

Ceriporic acids are a class of alk(en)ylitaconic acids produced by a selective lignin-degrading fungus, Ceriporiopsis subvermispora. The unique function of alkylitaconic acid is the redox silencing of the Fenton reaction system by inhibiting reduction of Fe 3+. Ceriporic acids have an asymmetric centre at carbon-3, but absolute configuration has not been determined. We have isolated a series of ceriporic acids from the cultures of C. subvermispora, and measured their NMR spectra using a chiral shift reagent. In comparison with NMR spectra of ( R)-(−)- and ( S)-(+)-methylsuccinic acid and those of natural and chemically synthesized racemic mixtures of ceriporic acids, we have determined the absolute configuration of ceriporic acids as ( R)-3-tetradecylitaconic acid (ceriporic acid A), ( R)-3-hexadecylitaconic acid (ceriporic acid B) and ( R, Z)-2-(hexadec-7-enyl)-3-itaconic acid (ceriporic acid C). We herein discuss their stereoselective biosynthetic pathway and the structural diversity of fungal secondary metabolites.

Amino Acid Composition and Antioxidative Peptides from Protein Hydrolysates of Yellow Stripe Trevally (Selaroides leptolepis)

Hydrolysates from yellow stripe trevally meat with 15% degree of hydrolysis (DH) obtained using Alcalase (HA) and Flavourzyme (HF) following pH-stat method were characterized. Both hydrolysates, HA and HF, contained glutamic acid and glutamine as the major amino acids, while glycine was the dominant amino acid in fish flesh. Hydrolysates were also rich in aspartic acid, asparagine, alanine, lysine, and leucine. Essential amino acid/nonessential amino acid ratios were 0.55, 0.63, and 0.62 for flesh, HA, and HF, respectively. After separation on a Sephadex G-50 column, antioxidative activity of hydrolysate fractions was determined as Trolox equivalent antioxidant capacity. The fraction of HF with molecular weight (MW) of 1.77 kDa exhibited the strongest antioxidative activity, compared with other fractions. Among all fractions of HA, the one having a MW of 2.44 kDa showed the highest antioxidative activity. Thereafter, the selected Sephadex G-50 fractions from both HA and HF were further chromatographed using a Sephadex C-25 column, followed by HPLC. MW of antioxidative peptides from HA and HF determined by Maldi TOF/TOF was 656 and 617 Da, respectively. However, peptides isolated from both HA and HF possessed a lower antioxidative activity than Trolox at the same concentration (P < 0.05). HA and HF prevented DNA oxidative damage in Fenton reaction system tested by in vitro plasmid DNA relaxation assay. These results indicate that hydrolysates from yellow stripe trevally can be used as an important source of amino acids and serve as alternative natural antioxidants.

Free Radical Scavenging Activity and Inhibitory response of Ziziphus mauritiana (Lamk.) Seed Extract on Alcohol-Induced Oxidative Stress

The antioxidant activity within the body has been well correlated with the body’s defense mechanism against toxic free radicals. Alcohol ingestion increases the generation of free radicals. The present study was conducted to assess antioxidant potential of seed extract of Ziziphus mauritiana, which was standardized with HPLC. DPPH assay and Fenton reaction system was applied to assess free radical scavenging potential. The Swiss albino mice were used to evaluate the inhibitory activity of extract on oxidative stress induced by alcohol. The animals were treated with graded doses of extract (100-400 mg/kg body weight) before the administration of alcohol. After 6 weeks animals were sacrificed and their livers were assessed for catalase, superoxide dismutase, glutathione and lipid peroxidation. The results indicated that the extract of Ziziphus mauritiana potentially scavenged the free radicals in a concentration-dependent manner. The pretreatment of animals with Ziziphus mauritiana extract inhibited lipid peroxidation significantly, and increased the levels of reduced glutathione, catalase activity and superoxide dismutase in all extract treated groups (p&lt;0.05) as compared to alcohol treated groups. The plant provides protection against the induction of oxidative stress by alcohol either by converting free radicals into stable products or by strengthening the antioxidant system.

De novo synthesis of ( Z)- and ( E)-7-hexadecenylitaconic acids by a selective lignin-degrading fungus, Ceriporiopsis subvermispora

Ceriporic acids are a class of alk(en)ylitaconic acids produced by a selective lignin-degrading fungus, Ceriporiopsis subvermispora. Their structural units have similarity with biologically important lichen acids, such as chaetomellic and protolichesterinic acids. The unique function of alkylitaconic acid is the redox silencing of the Fenton reaction system by inhibiting reduction of Fe 3+. As estimated by the catalytic function of Δ9-desaturases, 7-hexadecenyl derivatives bearing a trans configuration have not been reported in the family of alk(en)ylitaconic acids, i.e. the structurally similar lichen acids—alk(en)ylcitraconic and paraconic acids. In this paper, we discuss the isolation of an itaconic acid derivative with an ( E)-7-hexadecenyl chain from cultures of C. subvermispora. To identify the natural metabolite, ( E)- and ( Z)-7-hexadecenylitaconic acids were chemically synthesised. The isolated metabolite was identical to the synthetic ( E)-hexadecenylitaconic acid and was designated as ceriporic acid D. Administration of 13C-[U]-glucose demonstrated that ceriporic acid C and trans-7-hexadecenylitaconic acid (ceriporic acid D) were biosynthesised de novo by C. subvermispora.

Rapid quantitative determination of hydrogen peroxide by oxidation decolorization of methyl orange using a Fenton reaction system

In this study, a sensitive and rapid method for hydrogen peroxide (H 2O 2) determination has been developed with the aid of oxidation decolorization of methyl orange (MO) by using Fenton reactions, because the decolorization extent of MO solution (at the maximum absorption wavelength of 507 nm) is proportion to the concentration of H 2O 2. Under optimum conditions, this spectrophotometric method for the H 2O 2 analysis yields a dynamic range of H 2O 2 concentration from 5.0 × 10 −7 to 1.0 × 10 −4 mol L −1 ( r = 0.997) and a detection limit (3 σ/ k) of 2.0 × 10 −7 mol L −1. This method for the determination of H 2O 2 (0.04 mmol L −1) is able to tolerate the interference from NaCl (0–5.0 mmol L −1), Na 2SO 4 (0–5.0 mmol L −1), MgCl 2 (0–5.0 mmol L −1), sodium humate (0–0.1 mmol L −1), benzene (0–0.2 mmol L −1), toluene (0–0.2 mmol L −1), chlorobenzene (0–0.2 mmol L −1) and chloroform (0–0.2 mmol L −1). The analysis results for practical rainwater samples are in good agreement with the classical N, N-diethyl- p-phenylenediamine (DPD) method for H 2O 2 determination.

Extraction and Characterization of Antioxidant Compositions From Fermented Fruit Juice of Morinda citrifolia (Noni)

Extraction and characterization of antioxidative compositions from the extracts of fermented Xisha Noni ( Morinda citrifolia L.) juice were studied. The antioxidative constituents of 184.6 g freeze-dried extracts of naturally fermented Xisha Noni juice were isolated successfully by petroleum ether, EtOAc and n-BuOH solvents, and the antioxidative effects were measured according to scavenging activity against hydroxyl generated in Fenton reaction system and superoxide anion radicals in pyrogallol autoxidation system. The EtOAc extract exhibited most significantly higher ( P < 0.01) antioxidative activity than mannitol or vitamin C, while the petroleum ether and n-BuOH extracts showed lower activities compared to mannitol. Three antioxidant phenolic compounds, isoscopoletin, aesculetin and 3, 3′, 4′, 5, 7-pentahydroxyflavone (quercetin) were isolated from the EtOAc extract by several chromatography techniques for the first time. The results suggest that several compounds, in particular, the phenolic compounds, contribute separately or synergistically to the antioxidative activity of fermented Noni fruit juice.

Clindamycin phosphate scavenges hydroxyl radical

Clindamycin phosphate (CLDMP) is effective against Gram-positive and anaerobic bacteria, and is known to have anti-inflammatory properties. To further study the anti-inflammatory properties of CLDMP, we examined the scavenging effects on superoxide anion and hydroxyl radical using an electron spin resonance (ESR) spin trapping method. In a hypoxanthine-xanthine oxidase reaction system, CLDMP did not scavenge superoxide anion. In a Fenton reaction system, however, CLDMP reduced the level of hydroxyl radical, and the scavenging activity of CLDMP against hydroxyl radical was more potent than that of mannitol. As the concentration which inhibits the formation of hydroxyl radical by 50% (IC(50)) of CLDMP was changed by the addition of a 10-fold amount of a spin trapping agent, 5,5-dimethyl-1-pyrroline-N-oxide, it is strongly suggested that CLDMP scavenges hydroxyl radical directly. This is the first report of the direct scavenging effect of CLDMP on hydroxyl radical, and the effect may improve the inflammatory response caused by invading bacteria.

Antioxidant Potential, Lipid Peroxidation Inhibition and Antimicrobial Activities of Satureja montana L. subsp. kitaibelii Extracts

The antioxidant activity of different Satureja montana L. subsp. kitaibelii extracts was tested by measuring their ability to scavenge reactive hydroxyl radical during the Fenton reaction, using ESR spectroscopy. Also, the influence of these extracts on lipid peroxyl radicals obtained during lipid peroxidation of: (I) sunflower oil (37°C, 3h) inducedby 4,4'-azobis(4-cyanovaleric acid) (ACVA) and (II) liposomes induced by 2,2'-azobis(2-amidino-propane)dihydrochloride (AAPH) was studied. n-Butanol extract had the bestantioxidant activity (100% at 0.5 mg/mL in Fenton reaction system; 89.21% at 5 mg/mL in system I; 83.38% at 5 mg/mL in system II). The antioxidant activities of the extracts significantly correlated with total phenolic content. The antimicrobial activity of Satureja montana L. subsp. kitaibelii extracts was investigated. Petroleum ether, chloroform and ethyl acetate extracts expressed a wide range of inhibiting activity against both gram-positive and gram-negative bacteria.

Reactive Effect of Low Intensity He-Ne Laser upon Damaged Ultrastructure of Human Erythrocyte Membrane in Fenton System by Atomic Force Microscopy

To find out the mechanism of modulating the deformability of erythrocytes with low intensity He-Ne laser action, we studied the effect of low intensity He-Ne laser on the ultrastructure of human erythrocyte membrane. Erythrocytes were treated with free radicals from a Fenton reaction system before exposing them to low intensity He-Ne laser. The ultrastructure of damaged erythrocyte membrane was examined by atomic force microscopy. The results showed that the erythrocyte membrane became very rough and the molecules on the surface of the membrane congregated into particles of different magnitudes sizes after treating with free radicals. Comparing the degree of congregation of the molecular particles in the non-irradiated group and the He-Ne laser irradiated (9 mW and 18 mW) group, we found the average size of molecular particles in the laser irradiated group was smaller than that in the non-irradiated group, indicating that the low intensity laser had repairing function to the damage of erythrocyte membrane produced by the free radicals.

In vitro scavenging activity for reactive oxygen species by N‐substituted indole‐2‐carboxylic acid esters

The hydroxyl radical (HO*)- and superoxide anion radical (O* (2))-scavenging activity, as well as the singlet oxygen ((1)O(2))-quenching property of N-substituted indole-2-carboxylic acid esters (INDs) were investigated by deoxyribose degradation assay, a chemiluminescence method and the electron spin resonance (ESR) spin-trapping technique. This novel group of compounds was developed as a search for cyclooxygenase-2 (COX-2)-selective enzyme inhibitors. The results obtained demonstrated that of the 16 compounds examined, five inhibited light emission from the superoxide anion radical (O* (2))-DMSO system by at least 60% at a concentration of 1 mmol/L, nine prevented the degradation of deoxyribose induced by the Fenton reaction system (range 3-78%) or scavenged hydroxyl radicals (HO*) directly (range 8-93%) and 14 showed the (1)O(2)-quenching effect (range 10-74%). These results indicate that majority of the indole esters tested possess the ability to scavenge O(-) (2) and HO radicals and to quench (1)O(2) directly, and consequently may be considered effective antioxidative agents.

Antioxidant activity of water and alcohol extracts of Thuja orientalis leaves

Water and alcohol extracts were prepared from dried and powdered leaves of Thuja orientalis (T. orientalis). The reducing power, total phenolic content, the 1,1-diphenyl-2-picrylhydrazyl scavenging activity, inhibitory effect on Fe (II)-EDTA-<TEX>$H_{2}O_{2}$</TEX> (Fenton reaction system) induced DNA damage and inhibitory effect on human red blood cell (RBC) hemolysis were evaluated in the present study. At a concentration of 200 mg, water and alcohol extracts of T. orientalis inhibited the hydrolysis of DNA by 72.859% and 65.312%, respectively. Water and alcohol extracts of T. orientalis also inhibited 2,2'-Azobis(2-amidinopropane) dihydrochloride induced RBC hemolysis to the extent of 69.30% and 54.55%, respectively. The reducing power and antioxidative activity of water extract was found to be more than that of alcohol extract. This is attributable to the presence of higher amount of phenolic compounds in water extract. The present results indicate that the T. orientalis extracts are rich sources of natural antioxidants and can protect DNA and human red blood cells against free radical induced oxidative damage.

Redox silencing of the Fenton reaction system by an alkylitaconic acid, ceriporic acid B produced by a selective lignin-degrading fungus, Ceriporiopsis subvermispora

The selective lignin-degrading fungus, Ceriporiopsis subvermispora secretes alkylitaconic acids (ceriporic acids) during wood decay. We reported that ceriporic acid B (hexadecylitaconic acid) was protective against the depolymerization of cellulose by the Fenton reaction. To understand the redox silencing effects, we analyzed the physicochemical and redox properties of itaconic, octylitaconic and hexadecylitaconic acids. The initial rate of HO production by the Fenton system with Fe(3+), H(2)O(2) and L-cysteine was suppressed by hexadecylitaconic and octylitaconic acids by 0.04 and 0.16 of the reaction rate without chelators. ESR, O(2) uptake and the assay of Fe(2+) with BPS demonstrated that Fe(3+) reduction by L-cysteine was suppressed by hexadecylitaconic and octylitaconic acids while the reaction of Fe(2+) with H(2)O(2) was not suppressed by the two alkylitaconic acids. Ligand exchange experiments with NTA demonstrated that Fe(3+) chelation by two carboxyl groups of alkylitaconic acids is a critical step in iron redox modulation. In stark contrast, the production of HO* and reduction of Fe(3+) were not suppressed by itaconic acid due to HO*--initiated degradation of the chelator. The strong redox silencing effects by a series of alkylitaconic acids have attracted interest in controlling microbial plant cell wall degradation and chemoprotection against cellular oxidative injury.

Antioxidant activities of different Teucrium montanum L. Extracts

SummaryThe sequential extraction of Teucrium montanum L. was realised with five solvents of different polarities (70% methanol, petroleum ether, chloroform, ethyl acetate, and n‐butanol) and HPLC method was used for identification of phenolic compounds. The total phenolic content of the extracts was determined spectrophotometrically according to the Folin–Ciocalteau procedure and range from 0 to 296 mg g−1. The antioxidant activity of extracts was tested by measuring their ability to scavenge reactive hydroxyl radical during the Fenton reaction, using electron spin resonance (ESR) spectroscopy. Moreover, the influence of these extracts on lipid peroxyl radicals obtained during lipid peroxidation of: (1) sunflower oil (37 °C, 3 h) induced by 4,4′‐azobis(4‐cyanovaleric acid) (ACVA) and (2) liposomes induced by 2,2′‐azobis(2‐amidino‐propane)dihydrochloride (AAPH) was studied. n‐Butanol extract, because of the highest content of total phenolic compounds (296 mg g−1) had the best antioxidant activity (100% at 0.16 mg mL−1 in Fenton reaction system; 90.57% at 5 mg mL−1 in system I; 100% at 5 mg mL−1 in system II).

Are the biological properties of kaempferol determined by its oxidation products?

Although flavonoid molecules have attracted considerable interest in recent years because of their antioxidant effect, there are considerable differences in their chemical properties. Electron paramagnetic resonance (EPR) spectroscopy was used to compare the oxidative free radical chemistry of two such molecules, kaempferol and luteolin, which have the same empirical formula but differ in the position of one OH group. Whereas the basic flavonoid structure remains intact in luteolin, structural changes occur in kaempferol after one-electron oxidation. Autoxidation of kaempferol in alkaline solution and oxidation by at pH 7 led to rapid fragmentation. In contrast, oxidation by horseradish peroxidase/hydrogen peroxide, xanthine/xanthine oxidase (X/XO) or a Fenton reaction system produced a radical whose structure appeared to be based on dimerisation of either the original or a fragment of the flavonoid. Hence, the biological properties of kaempferol are likely to be determined by the chemistry of its oxidation products.

Plant phenolic metabolites as the free radical scavengers and mutagenesis inhibitors

Plant secondary metabolites are involved in versatile functions on different levels in the plant organism. One of the roles is the scavenging of free radicals and the protection against excess oxidation caused by UV irradiation, chemical oxidants or pathogen attack or other kinds of stress. Involved are phenolic compounds from different classes such as numerous phenol carboxylic acids, hydroxylated flavonoids such as flavones, flavonols, leucocyanidins, anthocyanins and procyanidins as well as isoflavonoids. Many of these substances have been isolated from plant species possessing valuable and intensively studied medicinal properties. For assessment of the free radical scavenging and antioxidant capacity of phenolic complexes in plants the chemical in vitro (cell free) tests can be used for their relative simplicity and sometimes reasonable cost. Here, we describe the application of several antioxidant and anti-free radical spectrophotometric assays for testing the antioxidant abilities of some rarely studied plant species containing different classes of polyphenols. In addition, the antimutagenic bacterial assays were used to examine the in vivo genoprotective activity of these compounds against chemical mutagens. Among the investigated compounds there are lipophilic flavones and their glucuronides from Scutellaria baicalensis and Iridaceae-type isoflavonoids from Belamcanda chinensis. Phenolic acids, procyanidins and flavonols containing Lamiaceae species such as Leonurus sp, Lamium sp., Stachys officinalis, Marrubium vulgare, Galeopsis speciosa have been also studied to comprise wider spectrum of different types of polyphenolics. The assays used address the different aspects of antioxidant properties such as: free radical scavenging in aqueous and non-aqueous environment (ABTS and DPPH colorimetric tests), scavenging of enzymatically generated superoxide anion radical, transition metal reduction ability by phosphomolybdenum complex formation [2], protection against hydroxyl radical induced polyunsaturated lipid peroxidation in the Fenton reaction system. It is important to employ several antioxidant assays for each object as there are usually different mechanisms of the antioxidation involved that results in varying outcome depending on the test used. For example the polyphenolic mixture from Stachys officinalis showed the weakest potential in the DPPH discoloration test whereas was the strongest one in molybdate reduction assay what clearly indicates the complexity of the involved mechanisms. The antimutagenic activity of the extracted phenol complexes and isolated compounds correlates with free radical scavenging. In the Ames bacterial assays [1] the direct mutagenesis by chemical mutagens can be distinguished from the mutagenesis induced by activation of pro-mutagen with cytochrome P-450 enzymatic fractions. The aglycones were clearly more efficient than glycosides in inhibition of mutagenesis, the lipophilic flavone from Scutellaria baicalensis – baicalein being the most efficient. Other flavonoids were effective in inhibition of indirect mutagenesis that can be attributed to the inhibitory action against the pro-mutagen activating enzymes [3]. Free radical scavenging by the low molecular weight compounds can play an important role as the last line of defense against oxidative damage of the cells for they are more stable than enzymatic antioxidant apparatus and can be easily accumulated in stress conditions (e.g deposited in the cell wall or the vacuole). Superoxide scavenging can protect the cells against the production of deleterious peroxynitrite upon reaction of the relatively harmless superoxide with an important signaling molecule – nitric oxide. The activity of complex extracts is sometimes stronger than individual compounds, which can be interpreted as the necessity for preserving the native composition, more effective when acting in oxidation/reduction cascades and thereby able to reduce the formation of harmful oxidation end-products. The in planta function of the antioxidant and antigenotoxic compounds should be further explored in order to obtain the complete insight into their role in protecting the plant cell.

Investigation of the Molecular Nature of Low-molecular-mass Cobalt(II) Ions in Isolated Osteoarthritic Knee-joint Synovial Fluid

High field 1H NMR spectroscopy demonstrated that addition of Co(II) ions to osteoarthritic knee-joint synovial fluid (SF) resulted in its complexation by a range of biomolecules, the relative efficacies of these complexants/chelators being citrate ≫ histidine ∼ threonine≫glycine ∼ glutamate ∼ glutamine ∼ phenylalanine ∼ tyrosine > formate > lactate≫alanine > valine > acetate > pyruvate > creatinine, this order reflecting the ability of these ligands to compete for the available Co(II) in terms of (1) thermodynamic equilibrium constants for the formation of their complexes and (2) their SF concentrations. Since many of these SF Co(II) complexants (e.g. histidinate) serve as powerful •OH scavengers, the results acquired indicate that any of this radical generated from the Co(II) source in such complexes via Fenton or pseudo-Fenton reaction systems will be “site-specifically” scavenged. The significance of these observations with regard to cobalt toxicity and the in vivo corrosion of cobalt-containing metal alloy joint prostheses (e.g. CoCr alloys) is discussed.

Egg yolk phosvitin inhibits hydroxyl radical formation from the fenton reaction.

Phosvitin, a phosphoprotein known as an iron-carrier in egg yolk, binds almost all the yolk iron. In this study, we investigated the effect of phosvitin on Fe(II)-catalyzed hydroxyl radical ((.-)OH) formation from H(2)O(2) in the Fenton reaction system. Using electron spin resonance (ESR) with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and deoxyribose degradation assays, we observed by both assays that phosvitin more effectively inhibited (.-)OH formation than iron-binding proteins such as ferritin and transferrin. The effectiveness of phosvitin was related to the iron concentration, indicating that phosvitin acts as an antioxidant by chelating iron ions. Phosvitin accelerates Fe(II) autoxidation and thus decreases the availability of Fe(II) for participation in the (.-)OH-generating Fenton reaction. Furthermore, using the plasmid DNA strand breakage assay, phosvitin protected DNA against oxidative damage induced by Fe(II) and H(2)O(2). These results provide insight into the mechanism of protection of the developing embryo against iron-dependent oxidative damage in ovo.

Antioxidant capacity of cultured mammalian cells estimated by ESR method.

In the present study, the antioxidant capacity against hydrogen peroxide (H2O2), one of the stress-inducing agents, was investigated in two distinct cell lines: L-41 (human epithelial-like cells) and HLF (human diploid lung fibroblasts), which differ in tissue origin, life span in culture, proliferate activity, and special enzyme system activity. The cell antioxidant capacity against H2O2 was estimated by the electron spin resonance (ESR) spin-trapping technique in the Fenton reaction system via Fe+2 ion action with H2O2 resulting in hydroxyl radical generation. The effects of catalase inhibitors, such as sodium azide and 3-amino-1,2,4-triazole, on the antioxidant capacity of cells were tested. Based on our observation, it can be concluded that the defensive capacity of cells against H2O2 depends on the ratio between catalase/GPx/SOD and H2O2, especially at high-stress situations, and the intracellular balance of these enzymes are more important than the influence of the single component.