共查询到20条相似文献,搜索用时 31 毫秒
1.
V Roginsky 《Free radical research》2001,35(1):55-62
2-tert-butyl-(1), 2,6-dimethyl-(2), 2,5-dimethyl-(3), trimethyl-(4), and 2,3-dimethoxy-5-methyl-(5) substituted p-hydroquinones (QH2) were tested as a chain-breaking antioxidant during the oxidation of methyl linoleate (ML) in dodecyl sulfate micellar solution, pH 7.40, at 37 degrees C. In the absence of superoxide dismutase (SOD), all the studied QH2 displayed very moderate if any antioxidant capability. When 5-25 U/ml SOD was added, QH2 showed a pronounced ability to inhibit ML oxidation. The stoichiometric factor of inhibition was found to be about one for all the tested QH2 in the presence of SOD. The reactivities of QH2 to the ML peroxy radical increase in the order QH2 5 < QH2 3 < QH2 1 approximately QH2 2 < QH2 4; reactivity of QH2 4 exceeds that reported for the majority of phenolic antioxidants. The features of QH2 as an antioxidant in aqueous environment is likely associated with the reactivity of semiquinone (O.-) formed due to attack of the peroxy radical to QH2. O.- reacts readily with molecular oxygen with formation of superoxide (O2.-); in turn, O2.- attacks both to QH2 and ML (likely, as HO2.) that results in fast depleting QH2 and chain propagation, respectively. The addition of SOD results in purging a reaction mixture from O2.- and, as a corollary, in depressing undesirable reactions with the participation of O2.-. Under these conditions, QH2 displays the theoretically highest inhibitory activity which is determined solely by the reactivity of QH2 to the peroxy radical. 相似文献
2.
Karin A. Simon Giavarotti Luciano Rodrigues Tania Rodrigues Virginia B.C. Junqueira Luis A. Videla 《Free radical research》2013,47(1):35-42
Liver microsomal functions related to xenobiotic biotransformation and free radical production were studied in control rats and in animals subjected to L-3,3′,5-triiodothyronine (T3) and/or lindane administration as possible mechanisms contributing to oxidative stress, in relation to the activity of enzymes (superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), and glucose-6-phosphate dehydrogenase (G-6PDH)) and content of lipid-soluble vitamins (α-tocopherol, β-carotene, and lycopene) affording antioxidant protection. Lindane treatment in euthyroid rats at a dosage of 20 mg/kg did not modify the content of liver microsomal cytochromes P450 and b5, the activity of NADPH-cytochrome P450 reductase and NADH-cytochrome b5 reductase, and the production of superoxide radical (O·-2), as well as antioxidant systems, except for the reduction in lycopene levels. Hyperthyroidism elicited a calorigenic response and increased specific and molecular activities of NADPH-cytochrome P450 reductase, O·-2 generation, and G-6PDH activity, concomitantly with diminution in liver SOD and catalase activities and in α-tocopherol, β-carotene, and lycopene levels. The administration of lindane to hyperthyroid animals led to a further increase in the molecular activity of NADPH-cytochrome P450 reductase and in the O·-2 production/SOD activity ratio, and decrease of hepatic α-tocopherol content, in a magnitude exceeding the sum of effects elicited by the separate treatments, as previously reported for reduced glutathione depletion. Collectively, these data support the contention that the increased susceptibility of the liver to the toxic effects of acute lindane treatment in hyperthyroid state is conditioned by potentiation of the hepatic oxidative stress status. 相似文献
3.
To improve photodynamic activity of the parent hypocrellin B (HB), a tetra-brominated HB derivative (compound 1) was synthesized in high yield. Compared with HB, compound 1 has enhanced red absorption and high molar extinction coefficients. The photodynamic action of compound 1, especially the generation mechanism and efficiencies of active species (Sen·-, O·-2 and 1O2) were studied using electron paramagnetic resonance (EPR) and spectrophotometric methods. In the deoxygenated DMSO solution of compound 1, the semiquinone anion radical of compound 1 is photogenerated via the self-electron transfer between the excited and ground state species. The presence of electron donor significantly promotes the reduction of compound 1. When oxygen is present, superoxide anion radical (O·-2) is formed via the electron transfer from Sens·- to the ground state molecular oxygen. The efficiencies of Sens·- and O·-2 generation by compound 1 are about three and two times as much as that of HB, respectively. Singlet oxygen (1O2) can be produced via the energy transfer from triplet compound 1 to ground state oxygen molecules. The quantum yield of singlet oxygen (1O2) is 0.54 in CHCl3 similar to that of HB. Furthermore, it was found that the accumulation of Sens·- would replace that of O·-2 or 1O2 with the depletion of oxygen in the sealed system. 相似文献
4.
M.-C. Toufektsian S. Tanguy A. Jeunet J.G. de Leiris F.R. Boucher 《Free radical research》2013,47(4):393-405
Oxygen radical scavengers have been shown to prevent the development of ischemic preconditioning, suggesting that reactive oxygen species (ROS) might be involved in this phenomenon. In the present study, we have investigated whether direct exposure to ROS produced by photoactivated Rose Bengal (RB) could mimic the protective effects of ischemic preconditioning.Methods In vitro generation of ROS from photoactivated RB in a physiological buffer was first characterised by ESR spectroscopy in the presence of 2,2,6,6-tetramethyl-1-piperidone (oxoTEMP) or 5,5-dimethyl-1-pyrroline-N-oxide (DMPO). In a second part of the study, isolated rat hearts were exposed for 2.5 min to photoactivated RB. After 5 min washout, hearts underwent 30 min no-flow normothermic ischemia followed by 30 min of reperfusion.Results and Conclusions The production of singlet oxygen (1O2) by photoactivated RB in the perfusion medium was evidenced by the ESR detection of the nitroxyl radical oxoTEMPO. Histidine completely inhibited oxoTEMPO formation. In addition, the use of DMPO has indicated that (i) superoxide anions (O·-2) are produced directly and (ii) hydroxyl radicals (HO·) are formed indirectly from the successive O·-2 dismutation and the Fenton reaction. In the perfusion experiments, myocardial post-ischemic recovery was dramatically impaired in hearts previously exposed to the ROS produced by RB photoactivation (1O2, O·-2, H2O2 and HO·) as well as when 1O2 was removed by histidine (50 mM) addition. However, functional recovery was significantly improved when hearts were exposed to photoactivated RB in presence of superoxide dismutase (105 IU/L) and catalase (106 IU/L).Further studies are now required to determine whether the cardioprotective effects of Rose Bengal in presence of O·-2 and H2O2 scavengers are due to singlet oxygen or to other species produced by Rose Bengal degradation. 相似文献
5.
《Free radical research》2013,47(1):90-100
AbstractThe pharmacological activity of polyphenolic silibinin from milk thistle (Silybum marianum) is primarily due to its antioxidant property. However, this study found that silibinin promoted sustained superoxide (O2·–) production that was specifically scavenged by exogenous superoxide dismutase (SOD) in MCF-7 cells, while the activity of endogenous SOD was not changed by silibinin. Previous work proved that silibinin induced MCF-7 cell apoptosis through mitochondrial pathway and this study further proved that O2·– generation induced by silibinin was also related to mitochondria. It was found that respiratory chain complexes I, II and III were all involved in silibinin-induced O2·– generation. Moreover, it was found that silibinin-induced O2·– had protective effect, as exogenous SOD markedly enhanced silibinin-induced apoptosis. 相似文献
6.
R. Santus L.K. Patterson M. Bazin J.C. Mazière P. Morlière 《Free radical research》2013,47(5):409-419
The reaction of the superoxide radical anion (O-·2), with the semi-oxidized tryptophan neutral radical (Trp·) generated from tryptophan (Trp) by pulse radiolysis has been observed in a variety of functionalized Trp derivatives including peptides. It is found that the reaction proceeds 4–5 times faster in positively charged peptides, such as Lys-Trp-Lys, Lys-Gly-Trp-Lys and Lys-Gly-Trp-Lys-O-tert-butyl, than in solutions of the negatively charged N-acetyl tryptophan (NAT). However, the reactivity of O-·2 with the Trp· radical is totally inhibited upon binding of these peptides to micelles of negatively charged SDS and is reduced upon binding to native DNA. By contrast, no change in reactivity is observed in a medium containing CTAB, where the peptides cannot bind to the positively charged micelles. On the other hand, the reactivity of the Trp· radical formed from NAT with O-·2 is reduced to half that of the free Trp· in buffer but is markedly increased in CTAB micelles. The models studied here incorporate elements of the complex environment in which Trp· and O-·2 may be concomitantly formed in biological system and demonstrate the magnitude of the influence such elements may have on the kinetics of reactions involving these two species. 相似文献
7.
The effects of excess copper (Cu) on the accumulation of hydrogen peroxide (H2O2) and antioxidant enzyme activities in roots of the Cu accumulator Elsholtzia haichowensis Sun were investigated. Copper at 100 and 300 μM significantly increased the concentrations of malondialdehyde and H2O2, and the activities of catalase (E.C. 1.11.1.6), ascorbate peroxidase (E.C. 1.11.1.11), guaiacol peroxidase (GPOD, E.C. 1.11.1.7)
and superoxide dismutase (SOD, E.C. 1.15.1.1). Isoenzyme pattern and inhibitor studies showed that, among SOD isoforms, only
copper–zinc superoxide dismutase (CuZn–SOD) increased. Excess Cu greatly increased the accumulation of superoxide anion (O2
·−) and H2O2 in E. haichowensis roots. This study also provides the first cytochemical evidence of an accumulation of H2O2 in the root cell walls as a consequence of Cu treatments. Experiments with diphenyleneiodonium as an inhibitor of NADPH oxidase,
1,2-dihydroxybenzene-3,5-disulphonic acid as an O2
·− scavenger, and N-N-diethyldithiocarbamate as an inhibitor of SOD showed that the source of H2O2 in the cell walls could partially be NADPH oxidase. The enzyme can use cytosolic NADPH to produce O2
·−, which rapidly dismutates to H2O2 by SOD. Apoplastic GPOD and CuZn–SOD activities were induced in roots of E. haichowensis with 100 μM Cu suggesting that these two antioxidant enzymes may be responsible for H2O2 accumulation in the root apoplast. 相似文献
8.
Q. Zhang J. Z. Zhang W. S. Chow L. L. Sun J. W. Chen Y. J. Chen C. L. Peng 《Photosynthetica》2011,49(2):201-208
Low temperature (LT) is one of the major factors that limit crop production and reduce yield. To better understand the cold-tolerance
mechanism in the plantains, a sensitive cultivar Williams (Musa acuminata AAA cv. Williams) and a tolerant cultivar Cachaco (Musa paradisiaca ABB cv. Dajiao) were used. LT resulted in increased malondialdehyde (MDA) content, elevated contents of hydrogen peroxide
(H2O2) and superoxide radical (O2·−), and decreased photochemical efficiency (Fv/Fm) and net photosynthetic rate (P
N), but cv. Cachaco showed better LT tolerance than cv. Williams. After LT treatment for 120 h, total scavenging capability (DPPH· scavenging capability) in Williams showed a significant decrease but no significant alternations was found in Cachaco. Ascorbate
peroxidase (APX) and peroxidase (POD) displayed a significant increase but superoxide dismutase (SOD) showed no significant
alternations and catalase (CAT) showed a significant decrease in Cachaco after 120 h of LT treatment. All the four antioxidant
enzymes above showed a significant decrease in Williams after 120 h of LT treatment. Our results suggest that higher activities
of APX, POD, SOD, and DPPH· scavenging capability to a certain extent can be used to explain the higher cold tolerance in the plantain, which would provide
a theoretical guidance for bananas production and screening cold-resistant variety. 相似文献
9.
SummaryReactive oxygen species (ROS) such as hydrogen peroxide (H2O2), superoxide anion (O2?), and hydroxyl radical (OH?) have been implicated in mediating various pathological events such as cancer, atherosclerosis, diabetes, ischemia, inflammatory diseases, and the aging process. The glutathione (GSH) redox cycle and antioxidant enzymes—superoxide dismutase (SOD) and catalase (CAT)—play an important role in scavenging ROS and preventing cell injury. Pycnogenol has been shown to protect endothelial cells against oxidant-induced injury. The present study determined the effects of pycnogenol on cellular metabolism of H2O2 and O2? and on glutathione-dependent and -independent antioxidant enzymes in bovine pulmonary artery endothelial cells (PAEC). Confluent monolayers of PAEC were incubated with pycnogenol, and oxidative stress was triggered by hypoxanthine and xanthine oxidase or H2O2. Pycnogenol caused a concentration-dependent enhancement of H2O2 and O2? clearance. It increased the intracellular GSH content and the activities of GSH peroxidase and GSH disulfide reductase. It also increased the activities of SOD and CAT. The results suggest that pycnogenol promotes a protective antioxidant state by upregulating important enzymatic and nonenzymatic oxidant scavenging systems. 相似文献
10.
Nitric oxide, a gaseous free radical, is poorly reactive with most biomolecules but highly reactive with other free radicals. Its ability to scavenge peroxyl and other damaging radicals may make it an important antioxidant in vivo, particular in the cardiovascular system, although this ability has been somewhat eclipsed in the literature by a focus on the toxicity of peroxynitrite, generated by reaction of O·-2 with NO· (or of NO- with O2). On balance, experimental and theoretical data support the view that ONOO- can lead to hydroxyl radical (OH·) generation at pH 7.4, but it seems unlikely that OH· contributes much to the cytotoxicity of ONOO-. The cytotoxicity of ONOO- may have been over-emphasized: its formation and rapid reaction with antioxidants may provide a mechanism of using NO· to dispose of excess O·-2, or even of using O·-2 to dispose of excess NO·, in order to maintain the correct balance between these radicals in vivo. Injection or instillation of “bolus” ONOO- into animals has produced tissue injury, however, although more experiments generating ONOO- at steady rates in vivo are required. The presence of 3-nitrotyrosine in tissues is still frequently taken as evidence of ONOO- generation in vivo, but abundant evidence now exists to support the view that it is a biomarker of several “reactive nitrogen species”. Another under-addressed problem is the reliability of assays used to detect and measure 3-nitrotyrosine in tissues and body fluids: immunostaining results vary between laboratories and simple HPLC methods are susceptible to artefacts. Exposure of biological material to low pH (e.g. during acidic hydrolysis to liberate nitrotyrosine from proteins) or to H2O2 might cause artefactual generation of nitrotyrosine from NO-2 in the samples. This may be the origin of some of the very large values for tissue nitrotyrosine levels quoted in the literature. Nitrous acid causes not only tyrosine nitration but also DNA base deamination at low pH: these events are relevant to the human stomach since saliva and many foods are rich in nitrite. Several plant phenolics inhibit nitration and deamination in vitro, an effect that could conceivably contribute to their protective effects against gastric cancer development. 相似文献
11.
K. B. Shumaev V. Z. Lankin G. G. Konovalova M. A. Grechnikova A. K. Tikhaze 《Doklady. Biochemistry and biophysics》2016,469(1):305-308
Methylglyoxal at a concentration of 5 mM caused a significant inhibition of superoxide anion radical (O2·-) comparable to the effect of Tirone. In the process of O2·- generation in the system of egg phosphatidylcholine liposome peroxidation induced by the azo-initiator AIBN, a marked inhibition of chemiluminescence in the presence of 100 mM methylglyoxal was found. At the same time, methylglyoxal did not inhibit free radical peroxidation of low-density lipoprotein particles, which indicates the absence of interaction with methylglyoxal alkoxyl and peroxyl polyenoic lipid radicals. These findings deepen information about the role of methylglyoxal in the regulation of free radical processes. 相似文献
12.
Evren Yildiztugay Ceyda Ozfidan-Konakci Mustafa Kucukoduk 《Journal of plant research》2013,126(5):729-742
Sphaerophysa kotschyana is a Turkish endemic and endangered plant that grows near Salt Lake, in Konya, Turkey. However, little is known about the ability of this plant to generate/remove reactive oxygen species (ROS) or its adaptive biochemical responses to saline environments. After exposure of S. kotschyana to 0, 150, and 300 mM NaCl for 7 and 14 days, we investigated (1) the activities and isozyme compositions of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX), and glutathione reductase (GR); (2) the oxidative stress parameters NADPH oxidase (NOX) activity, lipid peroxidation (MDA), total ascorbate (tAsA) content, and total glutathione content (tGlut); and (3) ROS levels for superoxide anion radical (O 2 ·? ), hydrogen peroxide (H2O2), hydroxyl radicals (OH·), and histochemical staining of O 2 ·? and H2O2. H2O2 content increased after 14 days of salt stress, which was consistent with the results from histochemical staining and NOX activity measurements. In contrast, oxidative stress induced by 150 mM NaCl was more efficiently prevented, as indicated by low malondialdehyde (MDA) levels and especially at 7 days, by increased levels of SOD, POX, APX, and GR. However, at 300 mM NaCl, decreased levels of protective enzymes such as SOD, CAT, POX, and GR, particularly with long-term stress (14 days), resulted in limited ROS scavenging activity and increased MDA levels. Moreover, at 300 mM NaCl, the high H2O2 content caused oxidative damage rather than inducing protective responses against H2O2. These results suggest that S. kotschyana is potentially tolerant to salt-induced damage only at low salt concentrations. 相似文献
13.
《Luminescence》2003,18(1):49-57
The chemiluminescence reaction of lucigenin (Luc2+?2NO3?, N,N′‐dimethyl‐9,9′‐biacridinium dinitrate) at gold electrodes in dioxygen‐saturated alkaline aqueous solutions (pH 10) was investigated in detail by the use of electrochemical emission spectroscopy. We noted that both O2 and Luc2+ are reduced on a gold electrode in aqueous solution of pH 10 in almost the same potential region. From this fact, we expected chemiluminescence based on a radical–radical coupling reaction of superoxide ion (O2·?) and one‐electron reduced form of Luc2+ (Luc·+, a radical cation). Chemiluminescence was actually observed in the potential range where O2 and Luc2+ were simultaneously reduced at the electrodes. The effects were examined upon addition of enzymes, i.e. superoxide dismutase (SOD) and catalase, into the solution and the substitution of heavy water (D2O) for light water (H2O) as a solvent on the chemiluminescence. In the presence of native and active SOD, chemiluminescence was completely absent. On the other hand, chemiluminescence was observed, unchanged in the presence of either denatured and inert SOD or catalase. In addition, the amount of chemiluminescence in D2O solution was about three times greater than that in H2O solution. These results, together with cyclic voltammetric results, suggest that O2·? participates directly in the chemiluminescence but H2O2 does not, and the chemiluminescence results from the coupling reaction between O2·? and Luc·+ under the present experimental conditions. These chemically unstable species, O2·? and Luc·+, are produced during the simultaneous electroreduction of O2 and Luc2+. The coupling reaction between those radical species would lead to the formation of a dioxetane‐type intermediate and, finally, to chemiluminescence. The chemiluminescence reaction mechanism is discussed. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
14.
Effects of deficient (20mmol m?3) and sufficient (1000 mmol m?3) magnesium (Mg) supply and of varied light intensity (100 μmol m?2 s?1 to 580 μmol m?2 s?1) on paraquat-dependent chlorophyll destruction in bean (Phaseolus vulgaris) plants grown in nutrient solution were studied over a 12-d period using leaf discs or intact primary leaves. Treatment of leaf discs with 10mmol m 3 paraquat for 15h caused severe chlorophyll loss, especially with increasing light intensity. This chlorophyll destruction by paraquat was very much higher in Mg-sufficient than Mg-deficient leaves. The occurrence of paraquat resistance in Mg deficient leaves was already apparent after 6d growth in nutrient solution, i.e. before any decrease in chlorophyll or growth by Mg deficiency was evident. Also, following foliar application of paraquat (10–140 mmol m?3) to intact plants, Mg-deficient plants were much more resistant to paraquat, even following longer exposure duration (72 h) and four to 14 times higher paraquat concentrations than those received by Mg sufficient plants. From experiments where exogenous scavengers of superoxide radical (O2.-), hydroxyl radical (OH·) and singlet oxygen (1O2) were applied to leaf discs, it appears that O2.-, and partly, OH· are the main O2 species which contribute to chlorophyll destruction by paraquat. The results demonstrate that Mg-deficient bean plants become highly resistant to O2.--mediated and light-induced paraquat injury. The mode of this paraquat resistance is attributed to well-known stimulative effects of Mg deficiency on O2.- and H2O2 scavenging enzymes and antioxidants. 相似文献
15.
Raj K. Sairam Kumutha Dharmar S. Lekshmy Viswanathan Chinnusamy 《Acta Physiologiae Plantarum》2011,33(3):735-744
This study was conducted to examine the extent of oxidative stress and the role of antioxidant enzymes on hypoxia tolerance
in highly tolerant wild species Vigna luteola, and mung bean (Vigna radiata) cvs. T 44 (tolerant) and Pusa Baisakhi (susceptible). Two days of water-logging caused about 40–50% decline in superoxide
radical (O2
·−) and hydrogen peroxide (H2O2) contents in all the genotypes, however, further water-logging to 8 days caused significant increase in O2
·− and H2O2 contents, and the values were 80–90% of the control values. In control and revived plants O2
·− and H2O2 contents were higher in Pusa Baisakhi, while under water-logging stress T 44 and V. luteola showed greater increases in the O2
·− and H2O2 contents. Hypoxia induced increase in superoxide dismutase, ascorbate peroxidase, and glutathione reductase activities were
higher in T 44 and V. luteola compared with Pusa Baisakhi; and the increases in T 44 and V. luteola continued up to 8th day of water-logging, while in case of Pusa Baisakhi, the maximum increase was observed only on the 2nd
day of water-logging. Gene expression studies showed enhanced expression of cytosolic-Cu/Zn-superoxide dismutase (SOD) and cytosolic-ascorbate peroxidase (APX) in the roots of waterlogged V. luteola and T 44, while little expression was observed in control or treated plants of Pusa Baisakhi. PCR band products were cloned and
sequenced, and partial cDNAs of Cu/Zn-SOD and APX, respectively, were obtained. Results suggest that increase in the activity of antioxidant enzymes is to scavenge reactive
oxygen species produced both during and after relief from water-logging stress. 相似文献
16.
René Santus Larry K. Patterson Gordon L. Hug Marc Bazin Jean-Claude Mazière Patrice Morlière 《Free radical research》2013,47(4):383-391
The kinetics of O·-2 reaction with semi-oxidized tryptophan radicals in lysozyme, Trp·(Lyz) have been investigated at various pHs and conformational states by pulse radiolysis. The Trp·(Lyz) radicals were formed by Br·-2 oxidation of the 3–4 exposed Trp residues in the protein. At pH lower than 6.2, the apparent bimolecular rate is about 2 × 108M-1s-1; but drops to 8 × 107M-1s-1 or less above pH 6.3 and in CTAC micelles. Similarly, the apparent bimolecular rate constant for the intermolecular Trp·(Lyz) + Trp·(Lyz) recombination reaction is about (4-7 × 106M-1s-1) at/or below pH 6.2 then drops to 1.3-1.6 × 106M-1s-1 at higher pH or in micelles. This behavior suggests important conformational and/or microenvironmental rearrangement with pH, leading to less accessible semioxidized Trp· residues upon Br·-2 reaction. The kinetics of Trp·(Lyz) with ascorbate, a reducing species rather larger than O·-2 have been measured for comparison. The well-established long range intramolecular electron transfer from Tyr residues to Trp radicals-leading to the repair of the semi-oxidized Trp·(Lyz) and formation of the tyrosyl phenoxyl radical is inhibited by the Trp·(Lyz)+O·-2 reaction, as is most of the Trp·(Lyz)+Trp·(Lyz) reaction. However, the kinetic behavior of Trp·(Lyz) suggests that not all oxidized Trp residues are involved in the intermolecular recombination or reaction with O·-2. As the kinetics are found to be quite pH sensitive, this study demonstrates the effect of the protein conformation on O·-2 reactivity. To our knowledge, this is the first report on the kinetics of a protein-O·-2 reaction not involving the detection of change in the redox state of a prosthetic group to probe the reactivity of the superoxide anion. 相似文献
17.
Eve de Lamirande Geneviève Lamothe Michèle Villemure 《Free radical biology & medicine》2009,46(10):1420-1427
We studied the modulation of superoxide anion (O2·?) and nitric oxide (NO·) generation during human sperm capacitation (changes needed for the acquisition of fertility). The production of NO· (diaminofluorescein-2 fluorescence assay), but not that of O2·? (luminescence assay), related to sperm capacitation was blocked by inhibitors of protein kinase C, Akt, protein tyrosine kinase, etc., but not by those of protein kinase A. Extracellular calcium (Ca2+) controlled O2·? synthesis but extra- and intracellular Ca2+ regulated NO· formation. Zinc inhibited capacitation and formation of O2·? and NO·. Zinc chelators (TPEN and EDTA) and sulfhydryl-targeted compounds (diamide and N-ethylmaleimide) stimulated capacitation and formation of O2·? and NO·; superoxide dismutase (SOD) and nitric oxide synthase inhibitor (L-NMMA) prevented these events. Diphenyliodonium (flavoenzyme inhibitor) blocked capacitation and related O2·? synthesis but promoted NO· formation, an effect canceled by SOD and L-NMMA. NADPH induced capacitation and NO· (but not O2·?) synthesis and these events were blocked by L-NMMA and not by SOD. Integration of these data on O2·? and NO· production during capacitation reinforces the concept that a complex, but flexible, network of factors is involved and probably is associated with rescue mechanisms, so that spermatozoa can achieve successful fertilization. 相似文献
18.
《Luminescence》2004,19(1):1-7
Indole‐2 and 3‐carboxamides (IDs) are proposed to be selective cyclooxygenase inhibitors. Since cyclooxygenase‐1 may be involved in reactive oxygen species (ROS) production, we hypothesize that these indole derivatives have antioxidative properties. We have employed chemiluminescence (CL) and electron spin resonance (ESR) spin trapping to examine this hypothesis. We report here the results of a study of reactivity of 10 selected indole derivatives towards ROS. The following generators of ROS were applied: potassium superoxide (KO2) as a source of superoxide radicals (O2·?), the Fenton reaction (Co‐EDTA/H2O2) for hydroxyl radicals (HO·), and a mixture of alkaline aqueous H2O2 and acetonitrile for singlet oxygen (1O2). Hydroxyl radicals were detected as 5,5‐dimethyl‐1‐pyrroline‐N‐oxide (DMPO) spin adduct, whereas 2,2,6,6‐tetramethyl‐piperidine (TEMP) was used as a detector of 1O2. Using the Fenton reaction, 0.5 mmol/L IDs were found to inhibit DMPO‐?H radical formation in the range 7–37%. Furthermore the tested compounds containing the thiazolyl group also inhibited the 1O2‐dependent TEMPO radical, generated in the acetonitrile + H2O2 system. About 20% inhibition was obtained in the presence of 0.5 mmol/L IDs. 1 mmol/L IDs caused an approximately 13–70% decrease in the CL sum from the O2·? generating system (1 mmol/L). The aim of this paper is to evaluate these indole derivatives as antioxidants and their abilities to scavenge ROS. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
19.
喀斯特石生穗枝赤齿藓抗氧化防御系统对干旱胁迫的响应 总被引:2,自引:0,他引:2
为科学选择石漠化环境恢复治理的植物材料和深入了解岩生植物的耐旱机制,以喀斯特石生穗枝赤齿藓(Erythrodoutium juluceum)为实验材料,研究了干旱胁迫对其抗氧化酶防御系统的影响。结果表明:超氧化酶歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)活性,超氧阴离子(O-2·)、丙二醛(MDA)含量呈现出先升后降的趋势;类胡萝卜素(Car)含量一直升高,质膜相对透性呈现出"抛物线"的变化趋势,可溶性蛋白含量波动变化。因此,干旱胁迫早期由于O-2·等活性氧的增加而启动活性氧清除系统进行清除,是抵御干旱的一种协同反应;后期穗枝赤齿藓依然保持较强的自由基清除能力,具有极强的耐旱能力。所以在长期的进化过程中,喀斯特石生藓类形成具有适合干旱变化的系列生理和代谢机制,通过形态上的变化来降低水分的散失,通过生理上的调整来应付环境的恶劣变化,这对于在石漠化地区揭示苔藓植物的抗逆机制,利用苔藓植物的先锋拓荒作用治理石漠化生态环境以及对退化生态系统进行人工恢复治理具有重要价值。 相似文献
20.
红麻细胞质雄性不育系与保持系花药活性氧代谢差异比较 总被引:2,自引:0,他引:2
以红麻细胞质雄性不育系L23A及其保持系L23B为材料,比较其花药淀粉及可溶性糖含量变化并分析呼吸速率、活性氧产生速率、丙二醛(MDA)含量以及活性氧清除酶(POD、SOD)含量变化,来探讨活性氧伤害与红麻雄性不育的关系。结果表明:在小孢子发育的单核期,不育系呼吸速率与保持系差异不明显,但不育系花药O-2·含量高于保持系; 在双核期,不育系的呼吸速率明显低于其保持系,但不育系花药O-2·含量与保持系花药相近; 不育系在单核期和双核期的呼吸速率几乎没有变化,而保持系同一时期的呼吸速率呈明显增高趋势; 在不育系败育过程中,药隔维管组织中的大颗粒淀粉含量几乎不变,且不育系花药中的可溶性糖含量在单核期和双核期均低于保持系。推测是由于不育系花药中抗氰呼吸降低,一方面导致花药物质代谢和能量代谢的紊乱,不育系花药不能利用药隔组织中的淀粉粒,另一方面不能有效将细胞内过多电子通过抗氰呼吸传至O2,引致不育花药中O-2·升高,从而导致MDA含量在单核期和双核期均高于保持系,同时POD的活性在单核期及双核期均低于保持系,而SOD活性在单核期高于保持系,在双核期则低于保持系。不育系花药在发育中,花药O-2·和MDA过量积累,以及SOD和POD酶活性降低,导致活性氧产生与清除失去平衡,花粉败育。 相似文献