共查询到20条相似文献,搜索用时 15 毫秒
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Henry D. Connor Wenshi Gao Ronald P. Mason Ronald G. Thurman 《Free radical biology & medicine》1994,16(6):871-875
-(4-pyridyl-1-oxide)-N-t-butylnitrone (4-POBN) radical adducts from Folch (chloroform:methanol) extraction of blood of transplanted livers exhibited a large 6-line electron paramagnetic resonance (EPR) spectrum. Slow EPR sample preparation involving freezing and thawing prior to extraction over 15 min yielded a spectrum assigned as a lipid-derived free radical species, whereas rapid (< min) extraction without a freeze-thaw cycle yielded a mixture of radicals, one with coupling constants similar to the -hydroxymethyl-4-POBN adduct (4-POBN/.CH2OH). Extraction with purified chloroform, however, yielded a much weaker, probably lipid-derived signal. Use of 13C-methanol in the Folch extracting solution yielded a 12-line EPR spectrum, indicating that a new, highly reactive oxidant species from blood following liver transplantation can convert organic solvents used in tissue extractions to free radicals. This hypothesis was supported by simulation of EPR spectra of free radicals extracted rapidly with Folch, which indicated that the spectrum contained two carbon-centered species, one with hyperfine coupling constants similar to the -methylhydroxyl-4-POBN adduct, the other probably lipid-derived. Because the former originates from methanol in the Folch, extraction of samples with alcohol-free organic solvent is most likely superior when the potential for formation of stable oxidant species exists, such as after liver transplantation. 相似文献
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《Free radical research》2013,47(3-6):399-405
A review of the principal interactions of nitroxides with cells suggests that if these same phenomena occur with spin adducts the result could be considerable experimental confusion and error. In particular, these could lead to differential rates of loss of spin adducts, thereby potentially invalidating conclusions on the amounts or even the types of free radicals that are trapped. In addition. shuttling of electrons between nitroxides and hydroxylamines also very significantly could alter the amounts and types of spin adducts that are observed. 相似文献
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The effect of free radicals generated by PMS was studied for membrane damage in the presence of different ions in the erythrocyte model. The degree of membrane damage depended on the quality of ionic composition in the incubation medium. We supposed that the degree of membrane damage depends on the average life and concentration and/or reactivity of the free radicals generated. For control of this supposition free radicals were generated by PMS in the presence of Sodium-di-thionite in isosmotic, waterly systems with different ionic composition. At different time intervals the concentration of free radicals was measured by the ESR method. It seams that concentration of radicals depends on the qualitative composition of ionic milieu. The increase of the average life of free radicals generated by PMS is accompanied by decrease in their reactivity. This is reflected by a moderate membrane damage. 相似文献
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Native and high pressure-treated (water suspensions, 650 MPa) waxy maize starch, containing mainly amylopectin, and Hylon VII, rich in amylose, were studied for their ability to generate free radicals upon thermal treatment at 180–230 °C. The electron paramagnetic resonance (EPR) spectroscopy was used to characterize the nature, number and stability of radicals. Various stable and short living (stabilized by N-tert-butyl-α-phenylnitrone (PBN) spin trap) radical species were formed. It was found, that at given conditions the waxy maize starch reveals higher ability to generate radicals, than Hylon VII. The presence of water and high pressure pretreatment of starches, both resulted in the reduction of the amount of thermally generated radicals. The decrease in crystallinity of waxy maize starch and of Hylon VII, occurring upon high pressure treatment, leads to the increase of the relative amount of fast rotating component in the EPR spectrum of both types of starches. 相似文献
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A Kh Kogan V I Ershov I Ia Sokolova G R Alekperova 《Biulleten' eksperimental'no? biologii i meditsiny》1992,113(6):582-584
The paper is concerned with studies on generation of free radicals by donor leukocytes in plasma rich or poor in platelets. NBT test and chemiluminescence were employed. Platelets are shown to inhibit generation of free radicals. Changes in free radicals generation were studied under stimulation by zymosan and addition of washed platelet fraction. The conclusion is made that platelets inhibit leukocyte generation of free radicals by adsorption factors necessary for this process from plasma. 相似文献
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Free radicals are essential for the vasopressin (AVP) response to plasmatic hyperosmolarity. Noradrenergic afferents are the major projections on the supraoptic nucleus (SON) of the hypothalamus and stimulate the expression of AVP via a nitric oxide (NO) pathway. In this study, we investigated the mechanisms linking free radicals and noradrenaline (NA)-induced regulation of AVP. Analysis of Tg8 transgenic mice, invalidated for the monoamine oxidase-A gene and with consequently high levels of brain monoamines and AVP in the SON, showed that free radicals are more abundant in their SON than in that of wild-type mice (WT). Antioxidant superoxide dismutase 1 and 2 and catalase enzyme activities were also higher in these mice than in WT. This may explain the observed absence of cytotoxicity that would otherwise be associated with such high level of free radicals. Treatment of Tg8 mice with α-MPT, a blocking agent for NA synthesis, decreased both the production of free radicals and the AVP levels in the SON. Furthermore, incubation of ex vivo slices including the SON with NA increased the production of free radicals and AVP levels in wild-type mice. When NA was associated with α-lipoic acid, an antioxidant blocking the production of free radicals, AVP remained at its control level, indicating that free radicals are required for the effect of NA on the expression of AVP. In slices incubated with SNP, a producer of NO, free radicals and AVP levels increased. When NA was associated with L-NAME (a NO synthase blocker), the levels of free radicals and AVP were the same as in controls. Thus, the noradrenaline–NO pathway, which stimulates the expression of vasopressin, involves free radicals. This study provides further evidence of the physiological importance of free radicals, which should no longer be considered solely as cytotoxic factors. 相似文献
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K. T. Yamaguchi R. J. Stewart H. M. Wang S. E. Hudson M. Vierra A. Akhtar C. Hoffman D. George 《Free radical research》1992,16(3):167-174
Research in smoke inhalation has established that free radicals are produced from gases released during combustion and these species impair lung function. Using spin traps and their adducts in an animal model free radicals were measured. Various hyperbaric oxygen regimens were tested in an attempt to attenuate pulmonary damage caused by free radical reactions. Our data demonstrated that persistent oxygen- and carbon-centered free radicals are detectable in intravascular fluids after smoke inhalation. The smoke inhalation model showed however, clearing of spin trap adducts one hour after smoke exposure. Other researchers have found that when 100% oxygen is given at 1 atmosphere absolute (ATA) for 1 h, free radicals were not detectable. However, oxygen given at 2.5 ATA does produce detectable free radicals. With continued exposure at this pressure, the levels of free radicals increase for up to 60min. This study suggests that the level of free radical induced oxygen toxicity may be a function of oxygen pressure and duration of oxygen exposure. 相似文献
9.
超氧化物歧化酶在氧自由基所引起的癌变中的作用 总被引:1,自引:0,他引:1
詹嘉红 《氨基酸和生物资源》1997,19(3):48-50
超氧化物歧化酶是一类抗氧化酶,它能催化超氧阴离子自由基的歧化反应,对机体起保护作用。氧自由基在某些情况下会对机体产生损伤作用。文章就氧自由基的产生、氧自由基与致癌的关系,以及超氧化物歧化酶在氧自由基所引起的癌变中的作用等方面进行了综述。 相似文献
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Etsuo Niki 《Free radical research》2013,47(6):693-704
Remarkable progress has been achieved in the past 100 years in the field of free radical chemistry, biology and medicine since the discovery of free radicals in 1900. Free radical-mediated processes play a major role in the present industrial chemistry, but they also cause deleterious effects on rubber, plastics, oil products and foods. The importance of free radicals in vivo has been recognized increasingly from both positive and negative sides. Free radicals play an important role in phagocytosis, the production of some biologically essential compounds and possibly cell signaling. At the same time, they may cause oxidative modification of biological molecules, which leads to oxidative damage and eventually to various diseases, cancer and aging. The role and beneficial effects of antioxidants against such oxidative stress support this view. Furthermore, novel issues have been continuously found in this fascinating and yet controversial field of free radicals in biology. In this short article, the past work, present problems and future perspectives of free radicals in life science will be briefly discussed. 相似文献
12.
Free radicals in the 1900's: from in vitro to in vivo 总被引:3,自引:0,他引:3
Niki E 《Free radical research》2000,33(6):693-704
Remarkable progress has been achieved in the past 100 years in the field of free radical chemistry, biology and medicine since the discovery of free radicals in 1900. Free radical-mediated processes play a major role in the present industrial chemistry, but they also cause deleterious effects on rubber, plastics, oil products and foods. The importance of free radicals in vivo has been recognized increasingly from both positive and negative sides. Free radicals play an important role in phagocytosis, the production of some biologically essential compounds and possibly cell signaling. At the same time, they may cause oxidative modification of biological molecules, which leads to oxidative damage and eventually to various diseases, cancer and aging. The role and beneficial effects of antioxidants against such oxidative stress support this view. Furthermore, novel issues have been continuously found in this fascinating and yet controversial field of free radicals in biology. In this short article, the past work, present problems and future perspectives of free radicals in life science will be briefly discussed. 相似文献
13.
HyoBong Hong Hans Joachim Krause SungWon Sohn TaiKyong Baik Jong Hyun Park SungWoong Shin ChiHu Park DaeYong Song 《Analytical biochemistry》2014
Frequency mixing magnetic detection (FMMD) was used to detect superoxide from hypoxanthine and xanthine reaction and to detect hydroxyl radical from the Fenton reaction. FMMD was also applied to measure the reactive oxygen species (ROS) level released from microglial cells. We could assess the formation and extinction of the free radicals without a spin trap reagent. The FMMD signal amplitude scaled with the concentration of the radicals. It was verified that no signals are obtained from the substrates and reagents. Based on the observations and on previous research, we suggest that the FMMD signals originate from superoxide and hydroxyl radicals, indicating that FMMD can be used to detect O-centered radicals. Subsequent analysis of free radicals generated from living microglial cells showed that there were significant differences between the activated microglial cells and resting ones. The results of this research are promising regarding the applications of FMMD for in situ measurement of free radicals from various sources, including the cell. 相似文献
14.
Lipid peroxyl radicals resulting from the peroxidation of polyunsaturated fatty acids by soybean lipoxygenase were directly detected by the method of rapid mixing, continuous-flow electron spin resonance spectroscopy. When air-saturated borate buffer (pH 9.0) containing linoleic acid or arachidonate acid was mixed with lipoxygenase, fatty acid-derived peroxyl free radicals were readily detected; these radicals have a characteristic g-value of 2.014. An organic free radical (g = 2.004) was also detected; this may be the carbon-centered fatty acid free radical that is the precursor of the peroxyl free radical. The ESR spectrum of this species was not resolved, so the identification of this free radical was not possible. Fatty acids without at least two double bonds (e.g. stearic acid and oleic acid) did not give the corresponding peroxyl free radicals, suggesting that the formation of bisallylic carbon-centered radicals precedes peroxyl radical formation. The 3.8-G doublet feature of the fatty acid peroxyl spectrum was proven (by selective deuteration) to be a hyperfine coupling due to a gamma-hydrogen that originated as a vinylic hydrogen of arachidonate. Arachidonate peroxyl radical formation was shown to be dependent on the substrate, active lipoxygenase, and molecular oxygen. Antioxidants are known to protect polyunsaturated fatty acids from peroxidation by scavenging peroxyl radicals and thus breaking the free radical chain reaction. Therefore, the peroxyl signal intensity from micellar arachidonate solutions was monitored as a function of the antioxidant concentration. The reaction of the peroxyl free radical with Trolox C was shown to be 10 times slower than that with vitamin E. The vitamin E and Trolox C phenoxyl radicals that resulted from scavenging the peroxyl radical were also detected. 相似文献
15.
Viña J Gimeno A Sastre J Desco C Asensi M Pallardó FV Cuesta A Ferrero JA Terada LS Repine JE 《IUBMB life》2000,49(6):539-544
Exhaustive exercise generates free radicals. However, the source of this oxidative damage remains controversial. The aim of this paper was to study further the mechanism of exercise-induced production of free radicals. Testing the hypothesis that xanthine oxidase contributes to the production of free radicals during exercise, we found not only that exercise caused an increase in blood xanthine oxidase activity in rats but also that inhibiting xanthine oxidase with allopurinol prevented exercise-induced oxidation of glutathione in both rats and in humans. Furthermore, inhibiting xanthine oxidase prevented the increases in the plasma activity of cytosolic enzymes (lactate dehydrogenase, aspartate aminotransferase, and creatine kinase) seen after exhaustive exercise. Our results provide evidence that xanthine oxidase is responsible for the free radical production and tissue damage during exhaustive exercise. These findings also suggest that mitochondria play a minor role as a source of free radicals during exhaustive physical exercise. 相似文献
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Masanori Kaneko Hisamichi Masuda Hideki Suzuki Yuji Matsumoto Akira Kobayashi Noboru Yamazaki 《Molecular and cellular biochemistry》1993,125(2):163-169
This study was undertaken to investigate the effects of oxygen free radicals on myofibrillar creatine kinase activity. Isolated rat heart myofibrils were incubated with xanthine+xanthine oxidase (a superoxide anion radical-generating system) or hydrogen peroxide and assayed for creatine kinase activity. To clarify the involvement of changes in sulfhydryl groups in causing alterations in myofibrillar creatine kinase activity, 1) effects of N-ethylmaleimide (sulfhydryl groups reagent) on myofibrillar creatine kinase activity, 2) effect of oxygen free radicals on myofibrillar sulfhydryl groups content, and 3) protective effects of dithiothreitol (sulfhydryl groups-reducing agent) on the changes in myofibrillar creatine kinase activity due to oxygen free radicals were also studied. Xanthine+xanthine oxidase inhibited creatine kinase activity both in a time-and a concentration-dependent manner. Superoxide dismutase (SOD) showed a protective effect on the depression in creatine kinase activity caused by xanthine+xanthine oxidase. Hydrogen peroxide inhibited creatine kinase activity in a concentration-dependent manner; this inhibition was prevented by the addition of catalase. N-ethylmaleimide reduced creatine kinase activity in a dose-dependent manner. The content of myofibrillar sulfhydryl groups was decreased by xanthine+xanthine oxidase; this reduction was protected by SOD. Furthermore, the depression in myofibrillar creatine kinase activity by xanthine+xanthine oxidase was protected by the addition of dithiothreitol. Oxygen free radicals may inhibit myofibrillar creatine kinase activity by modifying sulfhydryl groups in the enzyme protein. The reduction of myofibrillar creatine kinase activity may lead to a disturbance of energy utilization in the heart and may contribute to cardiac dysfunction due to oxygen free radicals. 相似文献
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Yang L Gong J Wang F Zhang Y Wang Y Hao X Wu X Bai H Stöckigt J Zhao Y 《Journal of enzyme inhibition and medicinal chemistry》2006,21(4):399-404
In this work, we evaluated the antioxidant properties of the eight novel silybin analogues for their capacity to scavenge free radicals including superoxide anion radicals and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals in vitro. Compound 7d demonstrated an excellent antioxidant effect in scavenging superoxide anion free radical with an IC50 value of 26.5 microM, while the IC50 of quercetin (the reference compound) was 38.1 microM. Compounds 7b, 7e, 7h showed certain scavenging activities for both types of free radicals. 相似文献
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N E Polyakov T V Leshina T A Konovalova L D Kispert 《Free radical biology & medicine》2001,31(3):398-404
The spin trapping EPR technique was used to study the influence of carotenoids (beta-carotene, 8'-apo-beta-caroten-8'-al, canthaxanthin, and ethyl 8'-apo-beta-caroten-8'-oate) on the yield of free radicals in the Fenton reaction (Fe(2+) + H(2)O(2) --> Fe(3+) + .OH + -OH) in the organic solvents, DMSO, and methanol. DMPO and PBN were used as spin trapping agents. It was demonstrated that carotenoids could increase or decrease the total yield of free radicals depending on the oxidation potential of the carotenoids and the nature of the radicals. A reaction mechanism is suggested which includes the reduction of Fe(3+) to Fe(2+) by carotenoids. The effectiveness of this carotenoid-driven Fenton reaction increases with a decrease of the scavenging rates for free radicals and with decreasing oxidation potentials of carotenoids. 相似文献
19.
The major unexplained phenomenon in fibrotic conditions is an increase in replicating fibroblasts. In this report we present evidence that oxygen free radicals can both stimulate and inhibit proliferation of cultured human fibroblasts, and that fibroblasts themselves release superoxide (O2.-) free radicals. Fibroblasts released O2.- in concentrations which stimulated proliferation, a finding confirmed by a dose-dependent inhibition of proliferation by free radical scavengers. Oxygen free radicals released by a host of agents may thus provide a very fast, specific and sensitive trigger for fibroblast proliferation. Prolonged stimulation may result in fibrosis, and agents which inhibit free radical release may have a role in the prevention of fibrosis. 相似文献
20.
The aging brain, metals and oxygen free radicals. 总被引:4,自引:0,他引:4
In this overview we bring together certa in facts and concepts that support the theory that the aging of "disease-free" brain is a consequence of the accumulated cellular-molecular modifications caused by oxygen free radicals. The relevance of transition metals, especially iron ions, in the production of oxygen free radicals, initiation of oxidative chain-reactions and in site-specific molecular modifications is documented. Mitochondria are identified as the major source of oxygen free radicals, and mitochondrial DNA is a likely target. Special attention is given to iron-sulfur clusters as sources of reactive iron and sites of modifications. Potential mechanisms by which oxygen free radicals can alter membrane receptors and intracellular signaling are cited. Although the evidence is still correlative, the oxygen free radical theory has strong experimental support and has promise for facilitating a better understanding of the "disease-free", aging brain. 相似文献