Superoxide Radical

To understand the biochemical events that control the generation of superoxide, the effect of inhibiting the respiratory complexes III and IV (C‐III and C‐IV) and alternative oxidase (AOX) on the rate of superoxide production was analyzed in mitochondria from maize seedlings. To increase superoxide production, it was required to inhibit C‐III or C‐IV by at least 30% or 50%, respectively. Below this inhibition threshold, AOX exerted the highest degree of control on superoxide production, whereas above it, the highest degree of control was exerted by C‐IV. The contribution of C‐III to control superoxide production became significant when AOX activity was modulated.

The 2,6-di-tert-butyl-4-methylphenol (1), and its analogues 2,6-di-tert-butylphenol (2), 2,4,6,-tri-tertbutylphenol (3), 2-tert-butylphenol (4), and 4-tert-butylphenol (5), were evaluated with respect to their reactivities with superoxide anion radical (O 2 -), using a variety of electrochemical methods including cyclic voltammetry and square wave voltammetry. The current intensity associated with anodic peak of O 2 -oxidation into O 2 (À1.16 ± 0.02 V) was used to measure effectiveness of compounds 1e5. All phenolic compounds reduced the anodic current intensity associated with O 2 -oxidation into O 2 . Compounds 2 and 4 produced reversible oxidation/reduction peaks associated with the corresponding quinones. The C 10% and C 60% values, related to the reduction of anodic O 2 -/O 2 current to 10% or 60% of its original value, were in 2.2e3.2 and 0.8e1.3 mM range, respectively. Compound 4 exhibited the lowest C 10% and C 60% values and was the most effective radical quencher. Data indicate that compounds belonging to the same class exhibited different radical activity (extent of reactivity with O 2 -), and that electrochemical methods are extremely useful in analyzing reactivity patterns in antioxidants of similar structures.

This research aimed to extract and describe a functional polymeric compound from Sepia kobiensis cuttlebone and investigate its potential to impede the oxidation process. Cuttlebone waste is readily available and regularly discarded, making it an ideal resource for extracting useful bioactive compounds. The isolation technique created a pure polymeric substance by solvent extraction, precipitation, and purification. Several analytical methods, such as Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM), were utilized to describe the isolated polymeric material. The study found that the separated material has a specific polymeric structure with functional groups linked to antioxidant action. Furthermore, the study evaluated the bioactivity of the isolated substance by measuring its ability to suppress oxidation processes in a model system. The material demonstrated high antioxidant activity by preventing reactive oxygen species (ROS) formation and scavenging free radicals. This action was attributed to the presence of antioxidant moieties within the structure as well as its polymeric nature. Finally, a bioactive polymeric substance with significant antioxidant properties was successfully isolated and characterized from the cuttlebone of Sepia kobiensis. The findings demonstrate how cuttlebone debris may be a valuable source of bioactive compounds and aid in the development of naturally occurring antioxidants for application in the culinary, cosmetic, and pharmaceutical industries. Further research is required to properly investigate its bioactivities and understand the underlying mechanisms of action.

The effects of supplemental ultraviolet-B (s-UV-B; 3.6 kJ m-2 day-1 above ambient) radiation on plant metabolite profile and free radical scavenging activities of Withania somnifera (an indigenous medicinal plant) under field conditions were investigated. The metabolite profiles of both leaves and roots were analyzed via GC-MS. The methanolic extracts were examined for their DPPH radical-, superoxide radical-, hydrogen peroxide-, hydroxyl radical-, and nitric oxide radical scavenging activities, ferrous ion chelating activity, and reducing power. GC-MS profile of leaves revealed increment in compounds such as isophytol (138.1 %), b-stigmasterol (183.05 %), trans-squalene (233.3 %), and Withaferin A (155.0 %), while compounds such as eugenol, b-carotene, lycopene, and vitamin E were detected in s-UV-B-treated leaves only. In roots, compounds such as ledol, neophytadiene, palmitic acid, retinol, sitosteryl oleate, and campesterol registered their presence only under s-UV-B. Methanolic extracts of treated plant organs were found to be more potent as free radical scavengers (their EC 50 values being lower than those of control extracts). Anomalies were observed for nitric oxide radical scavenging in both leaves and roots. The present study indicates that s-UV-B alters the composition and contents of plant metabolites leading to an increase in their free radical scavenging activities. Hence, s-UV-B-treated plant organs might be more effective in combating oxidative stress as well as from a nutritional and health perspective.

Context: The snail hemolymph is a multi-component mixture comprising various substances with pharmacological activity. Aims: To evaluate the antioxidant activity of hemocyanin and fractions isolated of hemolymph from garden snail Helix lucorum. Methods: The antioxidant activity was tested in chemical systems generating superoxide radicals (O2 •-) and hydroxyl radicals (• OH) and was presented as percent inhibition. The fractions' composition was analyzed by MALDI-TOF/TOF mass spectrometry. Results: At concentration of 90 µg/mL the hemolymph fraction with compounds with molecular weight (MW) <100kDa demonstrated the strongest O2 •-scavenger effect (82%), followed by the hemocyanin (58%), and hemolymph fraction with compounds with MW<1kDa (15%). The most powerful • OH scavenger effect at concentration of 90 µg/mL showed hemocyanin (43%) followed by MW<100kDa fraction (26%). No • OH scavenger effect was observed by the MW<1kDa fraction. The highest chelation properties (55%) were demonstrated by the MW<100kDa fraction at concentration of 130 µg/mL; both the hemocyanin and MW<1kDa hemolymph fraction showed 33% inhibitory effect at the same concentration. The analysis of the composition of the tested fractions revealed high content of hydrophobic surfaces in MW<1kDa fraction and presence of antioxidant enzymes-catalase, superoxide dismutase and glutathione peroxidase in MW<100kDa fraction that contribute to the overall antioxidant effect of H. lucorum hemolymph. Conclusions: The complex antioxidant effect of hemolymph from H. lucorum is thought to be related to the presence of low molecular weight peptides in the MW<1 kDa fraction including glutathione and mainly to the antioxidant enzymes in the MW<100 kDa fraction. Conclusiones: Los datos sugieren que el efecto antioxidante complejo de la hemolinfa de H. lucorum está relacionado con la presencia de péptidos de bajo peso molecular en la fracción de M<1 kDa que incluye glutatión y principalmente con la presencia de enzimas antioxidantes en el M<100 kDa fracción.

Medicinal plants are used by 80% of the world population as the only available medicines, especially in
the embryonic country. Stachytarpheta jamaicensis (S.jamaicensis) is widely known for its high medicinal
importance in traditional and folk medicinal systems in various countries. The objective of the present
study was designed to evaluate the fluorescent characters, presence of phytochemical composition,
quantify the total phenolic, alkaloids and flavonoid contents of aqueous extract of aerial part of
S.jamaicensis and its in vitro antioxidant potential against free radicals. The S.jamaicensis was powdered
and tested for fluorescence analysis, followed byextracted with aqueous and screened by qualitative and
quantitative phytochemicals analysis. The in vitro antioxidant potential of the extract was assessed by
using 1, 1-diphenyl-2-picryl-hydrazyl(DPPH), hydroxyl radical and superoxide radicals as free radical
scavengers by using the spectrophotometric method. During the preliminary phytochemical analysis of
this species exhibited the presence of phytochemical compounds like flavonoids, alkaloids, tannins,
triterpenoids, polyphenols and steroidsas major phytochemical groups while saponins and glycosides
were not detected. Alkaloids content of 12.78± 0.17 mg/100 gm, flavonoids and total phenolics content of
29.32 ±0.16 mg RE/ gm and 33.67 ±0.15 mg GAE/ gm respectively. The in vitro antioxidant activity of the
species, of S. jamaicensis aerial part extract required for 50% inhibition of DPPH radical scavenging effect
(IC50) was recorded as 172.87μg/mL,hydroxyl radical scavenging activity was recorded as 178.58 μg/mL
and superoxide radical scavenging activity was recorded as 232.79μg/mL. These findings clearly
demonstrated that the aerial part of the aqueous extract of S.jamaicensis possesses different bioactive compounds and has the potential to be a powerful antioxidant and appears to be an alternative to
synthetic antioxidants and this justifies its therapeutic usage.

The reactions of three hydroxy-and/or methoxy-substituted stilbenes with hydroxyl radicals (HO•) or with hydroxyl radicals and Superoxide radicals (HO• + Ο2 τ /Ηθ2•) under alkaline and acidic conditions have been studied. In this part, the course of the reactions other than cleavage of the conjugated double bond is described.

Using garnma-irradiation under carefully controlled conditions, the reactions of phenoxyl radicals from lignin model compounds of the guaiacoi and syringol types with Superoxide anion radicals (O 2 T) or their protonated forms, hydroperoxyl radicals (ΗΟ 2 •)< were studied. The reaction mixtures obtained after irradiation at different pFTs were analysed, and feasible pathways for the formation of the major products were proposed. The results reveal that, in alkaline media, Superoxide anion radicals mainly bring about opening of the aromatic rings, whereas in acidic media hydroperoxyl radicals may predominantly cause demethoxylation.

Eucommia ulmoides leaves were phytochemically and biologically studied for their antioxidant properties. Two new geniposides (ulmoside C and ulmoside D) and one known compound (10-O-acetylgeniposidic acid) were isolated from E. ulmoides. Evaluation of their free-radical scavenging activity with respect to DPPH, ABTS, and superoxide anions showed that ulmosides C and D possess outstanding properties with IC50 values of 6.5 ± 0.20 and 7.5 ± 0.01 mM (DPPH), 2.1 ± 0.007 and 3.5 ± 0.31 mM (ABTS), and 8.1 ± 0.17 and 10 ± 0.09 mM (superoxide anion), respectively.

Photoinduced electron-transfer oxygenation of 9,lO-dihydroanthracene was carried out with 2,4,6triphenylpyrylium tetrafluoroborate (TPP) and 9,lO-dicyanoanthracene (DCA) as sensitizers. The time course of the oxygenation products was studied, and the results showed that anthrone was formed as a primary product in the DCA-sensitized oxygenation whereas in the TPP-sensitized oxygenation anthracene was the primary, major product which under the reaction conditions was converted to anthrone. A mechanism involving proton transfer in the radical ion pair consisting of 9,10-dihydronathracene radical cation and superoxide radical anion, which cannot occur in the TPP-sensitized oxygenation, was proposed to rationalize the difference in the product distribution in the two sensitized oxygenation reactions.

DECPO, a new analogue of EMPO was synthesized through a two-step synthetic pathway. Its structure and its application to trap superoxide were investigated. The ESR detection of the DECPO-OOH spin adduct is easy even at low concentration of superoxide. In comparison with DEPMPO, the trapping of superoxide with DECPO is faster and the detection of DECPO-OOH can be performed using a very low nitrone concentration (0.5 mM).

Context: The snail hemolymph is a multi-component mixture comprising various substances with pharmacological activity. Aims: To evaluate the antioxidant activity of hemocyanin and fractions isolated of hemolymph from garden snail Helix lucorum. Methods: The antioxidant activity was tested in chemical systems generating superoxide radicals (O2 •-) and hydroxyl radicals (• OH) and was presented as percent inhibition. The fractions' composition was analyzed by MALDI-TOF/TOF mass spectrometry. Results: At concentration of 90 µg/mL the hemolymph fraction with compounds with molecular weight (MW) <100kDa demonstrated the strongest O2 •-scavenger effect (82%), followed by the hemocyanin (58%), and hemolymph fraction with compounds with MW<1kDa (15%). The most powerful • OH scavenger effect at concentration of 90 µg/mL showed hemocyanin (43%) followed by MW<100kDa fraction (26%). No • OH scavenger effect was observed by the MW<1kDa fraction. The highest chelation properties (55%) were demonstrated by the MW<100kDa fraction at concentration of 130 µg/mL; both the hemocyanin and MW<1kDa hemolymph fraction showed 33% inhibitory effect at the same concentration. The analysis of the composition of the tested fractions revealed high content of hydrophobic surfaces in MW<1kDa fraction and presence of antioxidant enzymes-catalase, superoxide dismutase and glutathione peroxidase in MW<100kDa fraction that contribute to the overall antioxidant effect of H. lucorum hemolymph. Conclusions: The complex antioxidant effect of hemolymph from H. lucorum is thought to be related to the presence of low molecular weight peptides in the MW<1 kDa fraction including glutathione and mainly to the antioxidant enzymes in the MW<100 kDa fraction. Conclusiones: Los datos sugieren que el efecto antioxidante complejo de la hemolinfa de H. lucorum está relacionado con la presencia de péptidos de bajo peso molecular en la fracción de M<1 kDa que incluye glutatión y principalmente con la presencia de enzimas antioxidantes en el M<100 kDa fracción.

RESUMEN Se extrajeron pigmentos de Attalea butyracea y se evaluó su contenido de fenoles, antocianinas y su capacidad atrapadora de los radicales libres DPPH•, encontrándose un Ic50 de 141.4 mg/l y una constante cinética k de 1.0512E-05 (g/L)-1s-1, en la evaluación de la capacidad atrapadora de los radicales superóxido (CARS) se encontró un Ic50 de 76 mg/L y la capacidad de inhibir la oxidación del β-caroteno fue pobre. Como patrones de referencia se utilizó BHA para DPPH• y β-caroteno, con un Ic50 de 5.6 mg/L y una k de 3.0372E-04 (g/L)-1s-1 y para CARS catequina, encontrándose un Ic50 de 72.3 mg/L.

The interaction of the oxazine dye gallocyanine with reactive oxygen (Н 2 О 2) and halogen (HOCl) species has been studied by spectrophotometry, mass spectrometry, and spectrofluorimetry. It has been shown that gallocyanine reacts with HOCl and (but not with Н 2 О 2) to form fluorescent products. It has been found using the inhibition assay that, both in the xanthine/xanthine oxidase system and in activated human blood neutrophils, the main contribution to the conversion of gallocyanine to a fluorophore comes from its reaction with The results obtained suggest that gallocyanine can act as a fluorogenic chemosensor and be used for estimating the activation of neutrophils and the NADPH-dependent production of superoxide anion radical by neutrophils and other blood cells, as well as for testing antioxidant drugs designed with the aim to correct diseases associated with oxidative stress.

While superoxide anion radical does not normally react with olefins, it does react with activated double bonds. Thus '0; oxidatively cleaves certain a&unsaturated ketones such as chalcones and tetracyclone and electron poor olefins such as 1.1-dicyano and 1.1-dinitro olcfins. Similarly '0; can react with substituted nitrobenzenes to yield the corresponding nitrophenols. EPR and oxygen labeling (KO:') experiments confirm an electron transfer mechanism.

Nitro Blue Tetrazolium (NBT) is a widely used chemical for the determination of superoxide anion radical (O 2-) and superoxide dismutase activity in many fundamental biological processes. Its reduction reaction with superoxide and the associated spectral absorption data of its reduction products, i.e., monoformazan (MF) and diformazan (DF), were studied in the current research. The molar extinction coefficient, ε, of each of these two reduction products in dimethyl sulfoxide (DMSO) were calculated to be 120 000 and 235 000 M-1 cm-1 , respectively. We propose quantifying these species as a means of obtaining superoxide anion radical concentration or as a general screening protocol for the efficacy of an antioxidant.

The mechanism of thymoquinone (2-isopropyl-5-methyl-1,4-benzoquinone) for scavenging peroxide radicals was explicated in gas phase and in liquid phase (benzene, water) using density functional theory approach. The calculated bond dissociation enthalpy, ionization potential, and proton dissociation enthalpy revealed that the H-atoms at positions 2-isopropyl and 5-methyl groups can be readily abstracted. In fact, the 2-isopropyl C-H bond dissociation enthalpy is lower than the 5-methyl C-H dissociation enthalpy. Analysis of spin density distribution indicates that H-atom abstraction in 2-isopropyl site generates more stable radical. The plots of highest occupied molecular orbital of thymoquinone demonstrate that the whole molecule can be easily attacked by electrophilic agents like radicals. In this paper, we studied the interaction of thymoquinone with hydroxyl, hydroperoxyl, and superoxide anion radicals, using potential energy surface scans and natural bond orbital analysis. Calculated potential energy barriers for hydroxyl radical attack (*2.5 kJ/ mol) revealed an instant scavenging by thymoquinone. Modeling of the reaction between thymoquinone and lipid peroxyl radical shows a barrier energy around 26.23 kJ/ mol.

Host animals in algal-invertebrate endosymbiotic associations are exposed to photosynthetically generated hyperoxia while in sunlight, conditions conducive to photodynamic excitations and production of cytotoxic oxygen-derived radicals such as the superoxide anion and the hydroxyl radical (.OH). All previous evidence of oxyradical production in symbiotic associations has been circumstantial. We here present direct evidence, from electron paramagnetic resonance studies on tissue homogenates of the photosymbiont-containing sea anemone Anthopleura elegantissima (Brandt), of substantial light-dependent .OH and production that is abolished by dichlorophenyldimethylurea (DCMU), an inhibitor of photosynthesis. Shade-adapted A. elegantissima lacking endosymbiotic algae likewise show .OH production upon illumination. The latter flux is not dependent on photosynthesis, and DCMU has no effect. Rather, .OH production in apozooxanthellate anemones is via direct photoexcitations. The selective re...

One-electron reduction of dihydroxyanthraquinone derivatives was studied in dimethylsulfoxide solution by means of electrochemical and spectrophotometric methods. It was found that dihydroxyanthraquinone reduction in the presence of oxygen occurs according to an EC mechanism, the second step being oxygen reaction with semiquinone anion radical. This mechanism was confirmed by the dependence of CV curves on dihydroxyanthraquinone and oxygen concentration. Supplementary spectrophotometric and electrochemical studies of the dihydroxyanthraquinone-potassium superoxide system have shown that no covalent compound is formed between seminquinone anion radical and molecular oxygen and therefore the reaction following dihydroxyanthraquinone reduction involves electron and proton transfer from semiquinone anion radical to molecular oxygen to form hydroperoxyl radical and deprotonated dihydroxyanthraquinone. The rate constants of the electron-transfer reactions from semiquinone anion radical to moleculax oxygen were determined from the dependence of anthraquinone cathodic reduction peak potential and the corresponding anodic peak current on oxygen concentration. It was found that the rate constants increase with decreasing pK a of the hydroxyanthraquinones, which confirms the postulated mechanism.

Liver microsomal cytochrome P4502E1-dependent p-nitrophenol (PNP) hydroxylation and expression of cytochrome P4502E1 were studied in rats subjected to γ-hexachlorocyclohexane (HCCH) or L-3,3 , ,5triiodothyronine (T 3) administration as a possible mechanism contributing to superoxide radical (O 2 .-) generation. HCCH treatment (a single dose of 40 mg/kg body wt) produced a 43% increase in the content of total cytochrome P450, whereas T 3 (daily doses of 0.1 mg/kg body wt for two consecutive days) led to a 37% decrease. NADPHdependent O 2 .generation was elevated by HCCH and T 3 , expressed as either per mg of protein or per nmol of cytochrome P450, with a 135% enhancement in the O 2 .production/superoxide dismutase (SOD) activity ratios being observed in both conditions. This was partly due to depression of SOD activity. Concomitantly, the molecular activity of NADPH-cytochrome p450 reductase was enhanced by 90 and 69% by HCCH and T 3 , respectively. In these conditions, microsomal PNP hydroxylation showed increases of 58 and 45% in HCCH-and T 3-treated rats over control values, respectively, with a parallel 31% (HCCH) and 41% (T 3) enhancement in the content of cytochrome P4502E1 assessed by western immunoblotting. We conclude that HCCH and T 3 enhance the expression and activity of cytochrome P4502E1 and that of NADPH-cytochrome P450 reductase in rat liver, regardless of the changes in total cytochrome P450 content, representing major contributory mechanisms to microsomal NADPH-dependent O 2 .generation.

Background: Quercetin is considered one of the most studied flavonols widely found in fruits and vegetables. Food preparation and storage affect the level of quercetin in food, as these processes can cause a partial or complete reduction in flavonol levels. Quercetin, as a bioactive compound, has beneficial effects on the human body and with various diseases due to its potent antioxidant properties. Quercetin is a scavenger of free radicals and exerts its effects in various body fluids (e.g., saliva, synovial fluid, blood). Because of this, it is essential to know the effect of pH on its antioxidant properties.

Objective: This study aims to determine the antioxidant capacity of quercetin against superoxide radicals depending on pH using a spectroscopic method.

Methods: The antioxidant properties of quercetin in the concentration range from 5 to 50 μg/ml against superoxide radicals were measured at pH values of 6.5 to 8. Superoxide radicals were generated in the photooxidation reaction of methionine with riboflavin. Inhibition of superoxide radicals by quercetin was detected spectrophotometrically in reaction with NTB.

Results: Quercetin is an effective superoxide radical scavenger with the highest antioxidant capacity observed at a slightly acidic pH of 6.5. The antioxidant activity of quercetin increased with increasing concentration; effective antioxidant capacity of quercetin was in the experiment at a concentration above 30 µg/ml.

Conclusion: Quercetin is a widely occurring flavonoid with many beneficial effects on the human body related to its antioxidant properties. Quercetin is an effective scavenger of superoxide radicals. Its correct dosage, processing, and storage, which significantly affect the antioxidant properties of quercetin, have a considerable impact on the effects of quercetin in the prevention and treatment of diseases. Since pH significantly affects biochemical processes in living organisms, our results could contribute to expanding information on the antioxidant properties of quercetin as a rich natural source of medicinal substances, depending on pH.

Keywords:quercetin, antioxidant, superoxide radical, spectrophotometry

Advanced oxidation processes (AOPs) have known increased application to treat wastewaters containing recalcitrant compounds that are hardly degraded by conventional technologies. AOPs are characterized by the formation of strong oxidants such as hydroxyl radicals, superoxide anions, hydroperoxyl radicals and singlet oxygen, which react with the contaminant, contributing to its degradation. This paper provides an overview of the determination methods of reactive oxygen species, ROS, in the application of AOPs; the methods developed in the available literature for the detection and quantification of ROS are reviewed as a first step in the assessment and detailed description of the mechanisms involved in the oxidation reactions, focusing on the critical analysis of the main strengths and weaknesses presented by the probe molecules employed in the evaluated studies.

Context: The snail hemolymph is a multi-component mixture comprising various substances with pharmacological activity. Aims: To evaluate the antioxidant activity of hemocyanin and fractions isolated of hemolymph from garden snail Helix lucorum. Methods: The antioxidant activity was tested in chemical systems generating superoxide radicals (O2 •-) and hydroxyl radicals (• OH) and was presented as percent inhibition. The fractions' composition was analyzed by MALDI-TOF/TOF mass spectrometry. Results: At concentration of 90 µg/mL the hemolymph fraction with compounds with molecular weight (MW) <100kDa demonstrated the strongest O2 •-scavenger effect (82%), followed by the hemocyanin (58%), and hemolymph fraction with compounds with MW<1kDa (15%). The most powerful • OH scavenger effect at concentration of 90 µg/mL showed hemocyanin (43%) followed by MW<100kDa fraction (26%). No • OH scavenger effect was observed by the MW<1kDa fraction. The highest chelation properties (55%) were demonstrated by the MW<100kDa fraction at concentration of 130 µg/mL; both the hemocyanin and MW<1kDa hemolymph fraction showed 33% inhibitory effect at the same concentration. The analysis of the composition of the tested fractions revealed high content of hydrophobic surfaces in MW<1kDa fraction and presence of antioxidant enzymes-catalase, superoxide dismutase and glutathione peroxidase in MW<100kDa fraction that contribute to the overall antioxidant effect of H. lucorum hemolymph. Conclusions: The complex antioxidant effect of hemolymph from H. lucorum is thought to be related to the presence of low molecular weight peptides in the MW<1 kDa fraction including glutathione and mainly to the antioxidant enzymes in the MW<100 kDa fraction. Conclusiones: Los datos sugieren que el efecto antioxidante complejo de la hemolinfa de H. lucorum está relacionado con la presencia de péptidos de bajo peso molecular en la fracción de M<1 kDa que incluye glutatión y principalmente con la presencia de enzimas antioxidantes en el M<100 kDa fracción.

To understand the biochemical events that control the generation of superoxide, the effect of inhibiting the respiratory complexes III and IV (C-III and C-IV) and alternative oxidase (AOX) on the rate of superoxide production was analyzed in mitochondria from maize seedlings. To increase superoxide production, it was required to inhibit C-III or C-IV by at least 30% or 50%, respectively. Below this inhibition threshold, AOX exerted the highest degree of control on superoxide production, whereas above it, the highest degree of control was exerted by C-IV. The contribution of C-III to control superoxide production became significant when AOX activity was modulated.

Pigments of Attalea butyracea were extracted and it evaluated his content of phenols, anthocyanins and its scavenger capacity of free radicals DPPH•, being a Ic50 of 141, 4 mg/l and one kinetic constant k of 1.0512E-05 (g/L) - 1 s -1 , in the evaluation of the scavenger capacity of the superoxide radical (SCSR) was a Ic50 of 76 mg/L and the capacity to inhibit the oxidation of β-carotene was poor.

Antioxidant activity of methanolic extract of Abutilon indicum leaves was investigated for its free radical scavenging activity by determining the nitric oxide and superoxide radical scavenging activity. Maximum scavenging of nitric oxide and superoxide radical found were 28.74 % and 49. 62 % respectively at 250 µg/ml concentration.

Antioxidant activity of chloroform extract of Aesculus indica leaves was investigated for its free radical scavenging activity by determining the nitric oxide and superoxide radical scavenging activity. Maximum scavenging of nitric oxide and superoxide radical found were 27.62% and 48.65% respectively at 250 µg/ml concentration.

Context: The snail hemolymph is a multi-component mixture comprising various substances with pharmacological activity. Aims: To evaluate the antioxidant activity of hemocyanin and fractions isolated of hemolymph from garden snail Helix lucorum. Methods: The antioxidant activity was tested in chemical systems generating superoxide radicals (O2 •-) and hydroxyl radicals (• OH) and was presented as percent inhibition. The fractions' composition was analyzed by MALDI-TOF/TOF mass spectrometry. Results: At concentration of 90 µg/mL the hemolymph fraction with compounds with molecular weight (MW) <100kDa demonstrated the strongest O2 •-scavenger effect (82%), followed by the hemocyanin (58%), and hemolymph fraction with compounds with MW<1kDa (15%). The most powerful • OH scavenger effect at concentration of 90 µg/mL showed hemocyanin (43%) followed by MW<100kDa fraction (26%). No • OH scavenger effect was observed by the MW<1kDa fraction. The highest chelation properties (55%) were demonstrated by the MW<100kDa fraction at concentration of 130 µg/mL; both the hemocyanin and MW<1kDa hemolymph fraction showed 33% inhibitory effect at the same concentration. The analysis of the composition of the tested fractions revealed high content of hydrophobic surfaces in MW<1kDa fraction and presence of antioxidant enzymes-catalase, superoxide dismutase and glutathione peroxidase in MW<100kDa fraction that contribute to the overall antioxidant effect of H. lucorum hemolymph. Conclusions: The complex antioxidant effect of hemolymph from H. lucorum is thought to be related to the presence of low molecular weight peptides in the MW<1 kDa fraction including glutathione and mainly to the antioxidant enzymes in the MW<100 kDa fraction. Conclusiones: Los datos sugieren que el efecto antioxidante complejo de la hemolinfa de H. lucorum está relacionado con la presencia de péptidos de bajo peso molecular en la fracción de M<1 kDa que incluye glutatión y principalmente con la presencia de enzimas antioxidantes en el M<100 kDa fracción.

5-Diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide (DEPMPO) is frequently used as a spin trap for the measurement of superoxide by EPR spectrometry. However, its half life is fairly short in room temperature. We here show that superoxide radicals trapped by DEPMPO can be successfully recorded at ؊196°C. Moreover, we show that the signal intensity remains unaltered for up to 7 days, when the samples are stored in liquid nitrogen. Our new approach for measurement of superoxide should greatly simplify the studies of this important radical in biological systems.

The process of implantation of the blastocyst in the endometrium is considered analogous to a "proinflammatory" response, and a possibility exists that any compound showing good anti-inflammatory activity may also possess a significant anti-implantation potential. Leaf extract from the shrub Vitex negundo Linn has previously been studied for its analgesic and anti-inflammatory activities. Hence, anti-implantation activity of the methanolic extract of leaves of Vitex negundo Linn was investigated. Pregnant female mice were dosed with the extract (500 mg/kg body weight) from Days 1 to 6 of pregnancy. No implantation sites were observed in treated animals when they were surgically opened on Day 15 of pregnancy. Biophysical alterations were observed in the endometrium in treated animals, especially on Day 5 (4:40 a.m.), the day of implantation. A sharp increase in superoxide anion radicals that was seen in the endometrium from control animals was altered in treated animals. Thus, the physiological alterations induced by extract of Vitex negundo Linn during the process of implantation may serve as a good lead for further research on natural contraceptive targets.

Host animals in algal-invertebrate endosymbiotic associations are exposed to photosynthetically generated hyperoxia while in sunlight, conditions conducive to photodynamic excitations and production of cytotoxic oxygen-derived radicals such as the superoxide anion (O2−) and the hydroxyl radical (OH). All previous vidence of oxyradical production in symbiotic associations has been circumstantial. We here present direct evidence, from electron paramagnetic resonance studies on tissue homogenates of the photosymbiont-containing sea anemone Anthopleura elegantissima (Brandt), of substantial light-dependent OH and O2 production that is abolished by dichlorophenyldimethylurea (DCMU), an inhibitor of photosynthesis. Shade-adapted A. elegantissima lacking endosymbiotic algae likewise show OH production upon illumination. The latter flux is not dependent on photosynthesis, and DCMU has no effect. Rather, OH production in apozooxanthellate anemones is via direct photoexcitations. The selectiv...

The integrity of DNA purine bases was herein used to evaluate the antioxidant capacity. Unlike other DNA-based antioxidant sensors reported so far, the damaging agent chosen was the O ÅÀ 2 radical enzymatically generated by the xanthine/xanthine oxidase system. An adenine-rich oligonucleotide was adsorbed on carbon paste electrodes and subjected to radical damage in the presence/absence of several antioxidant compounds. As a result, partial damage on DNA was observed. A minor product of the radical oxidation was identified by cyclic voltammetry as a diimine adenine derivative also formed during the electrochemical oxidation of adenine/guanine bases. The protective efficiency of several antioxidant compounds was evaluated after electrochemical oxidation of the remaining unoxidized adenine bases, by measuring the electrocatalytic current of NADH mediated by the adsorbed catalyst species generated. A comparison between O ÅÀ 2 and OH Å radicals as a source of DNA lesions and the scavenging efficiency of various antioxidant compounds against both of them is discussed. Finally, the antioxidant capacity of beverages was evaluated and compared with the results obtained with an optical method.

Context: The snail hemolymph is a multi-component mixture comprising various substances with pharmacological activity. Aims: To evaluate the antioxidant activity of hemocyanin and fractions isolated of hemolymph from garden snail Helix lucorum. Methods: The antioxidant activity was tested in chemical systems generating superoxide radicals (O2 •-) and hydroxyl radicals (• OH) and was presented as percent inhibition. The fractions' composition was analyzed by MALDI-TOF/TOF mass spectrometry. Results: At concentration of 90 µg/mL the hemolymph fraction with compounds with molecular weight (MW) <100kDa demonstrated the strongest O2 •-scavenger effect (82%), followed by the hemocyanin (58%), and hemolymph fraction with compounds with MW<1kDa (15%). The most powerful • OH scavenger effect at concentration of 90 µg/mL showed hemocyanin (43%) followed by MW<100kDa fraction (26%). No • OH scavenger effect was observed by the MW<1kDa fraction. The highest chelation properties (55%) were demonstrated by the MW<100kDa fraction at concentration of 130 µg/mL; both the hemocyanin and MW<1kDa hemolymph fraction showed 33% inhibitory effect at the same concentration. The analysis of the composition of the tested fractions revealed high content of hydrophobic surfaces in MW<1kDa fraction and presence of antioxidant enzymes-catalase, superoxide dismutase and glutathione peroxidase in MW<100kDa fraction that contribute to the overall antioxidant effect of H. lucorum hemolymph. Conclusions: The complex antioxidant effect of hemolymph from H. lucorum is thought to be related to the presence of low molecular weight peptides in the MW<1 kDa fraction including glutathione and mainly to the antioxidant enzymes in the MW<100 kDa fraction.

Myrica gale L. (sweet gale) fruit leachate contains myrigalone A (MyA), a rare C-methylated dihydrochalcone and putative allelochemical, which is known to be a phytotoxin impeding seedling growth. We found that MyA inhibited Lepidium sativum L. seed germination in a dose-dependent manner. MyA did not affect testa rupture, but inhibited endosperm rupture and the transition to subsequent seedling growth. MyA inhibited micropylar endosperm cap (CAP) weakening and the increase in the growth potential of the radical/hypocotyl region (RAD) of the embryo, both being key processes required for endosperm rupture. We compared the contents of abscisic acid (ABA) and gibberellins in the tissues and found that the major bioactive forms of gibberellin in L. sativum seed tissues were GA(4) and GA(6), while GA(8) and GA(13) were abundant inactive metabolites. MyA did not appreciably affect the ABA contents, but severely interfered with gibberellin metabolism and signaling by inhibiting important steps catalyzed by GA3 oxidase, as well as by interfering with the GID1-type gibberellin signaling pathway. The hormonally and developmentally regulated formation of apoplastic superoxide radicals is important for embryo growth. Specific zones within the RAD were associated with accumulation of apoplastic superoxide radicals and endoreduplication indicative of embryo cell extension. MyA negatively affected both of these processes and acted as a scavenger of apoplastic reactive oxygen species. We propose that MyA is an allelochemical with a novel mode of action on seed germination.

Myrica gale L. (sweet gale) fruit leachate contains myrigalone A (MyA), a rare C-methylated dihydrochalcone and putative allelochemical, which is known to be a phytotoxin impeding seedling growth. We found that MyA inhibited Lepidium sativum L. seed germination in a dose-dependent manner. MyA did not affect testa rupture, but inhibited endosperm rupture and the transition to subsequent seedling growth. MyA inhibited micropylar endosperm cap (CAP) weakening and the increase in the growth potential of the radical/hypocotyl region (RAD) of the embryo, both being key processes required for endosperm rupture. We compared the contents of abscisic acid (ABA) and gibberellins in the tissues and found that the major bioactive forms of gibberellin in L. sativum seed tissues were GA 4 and GA 6 , while GA 8 and GA 13 were abundant inactive metabolites. MyA did not appreciably affect the ABA contents, but severely interfered with gibberellin metabolism and signaling by inhibiting important steps catalyzed by GA3 oxidase, as well as by interfering with the GID1-type gibberellin signaling pathway. The hormonally and developmentally regulated formation of apoplastic superoxide radicals is important for embryo growth. Specific zones within the RAD were associated with accumulation of apoplastic superoxide radicals and endoreduplication indicative of embryo cell extension. MyA negatively affected both of these processes and acted as a scavenger of apoplastic reactive oxygen species. We propose that MyA is an allelochemical with a novel mode of action on seed germination.