共查询到20条相似文献,搜索用时 31 毫秒
1.
Takuo Shiraishi Masao Makiuchi Katsuko Kakinuma Humio Inaba 《Photochemistry and photobiology》1998,68(1):16-19
Abstract— We report the detection of a weak near-infrared light emission originating from 8 nM singlet molecular oxygen (1 O2 ) produced in a mixture of 1 m M hypochlorite (OC1- ) and 8 n M hydrogen peroxide (H2 O2 ). The measurements were made with a highly sensitive detection system for ultraweak light emission in the 1.0-1.5 μm wavelength region. The emission intensity exhibited linear dependence for H2 O2 concentrations in the range of 8-670 n M . The mixture containing a lower concentration (33 μ M ) of OCl- pseudocontinuously emitted near-infrared light for 5 s. The rate constant for 1 O2 production obtained from the kinetic analysis agrees with that previously reported. Our results demonstrate the possibility of measuring very low concentrations of 1 O2 in a OCi-/H2 O2 mixture as well as 1 O2 production in intact living systems. 相似文献
2.
Kinetic and mechanistic aspects of the vitamin B2 (riboflavin [Rf])-sensitized photo-oxidation of the imidazoline derivates (IDs) naphazoline (NPZ) and tetrahydrozoline (THZ) were investigated in aqueous solution. The process appears as important on biomedical grounds, considering that the vitamin is endogenously present in humans, and IDs are active components of ocular medicaments of topical application. Under aerobic visible light irradiation, a complex picture of competitive interactions between sensitizer, substrates and dissolved oxygen takes place: the singlet and triplet (3 Rf*) excited states of Rf are quenched by the IDs: with IDs concentrations ca. 5.0 m m and 0.02 m m Rf, 3 Rf* is quenched by IDs, in a competitive fashion with dissolved ground state oxygen. Additionally, the reactive oxygen species: O2 (1 Δg ), O2 •− , HO• and H2 O2 , generated from 3 Rf* and Rf •− , were detected with the employment of time-resolved methods or specific scavengers. Oxygen uptake experiments indicate that, for NPZ, only H2 O2 was involved in the photo-oxidation. In the case of THZ, O2 •− , HO• and H2 O2 were detected, whereas only HO• was unambiguously identified as THZ oxidative agents. Upon direct UV light irradiation NPZ and THZ generate O2 (1 Δg. ), with quantum yields of 0.2 (literature value, employed as a reference) and 0.08, respectively, in acetonitrile. 相似文献
3.
GARY J. BACHOWSKI KIM M. MOREHOUSE ALBERT W. GIROTTI 《Photochemistry and photobiology》1988,47(5):635-645
Abstract— Photooxidation reactions in ascorbate (AH)-containing erythrocyte membrane suspensions have been studied in broad perspective by simultaneously monitoring lipid peroxidation in the membrane compartment and formation of hydrogen peroxide (H2 O2 ) and hydroxyl radical (OH) in the aqueous compartment. Non-bound uroporphyrin (UP) and membrane-bound protoporphyrin (PP) were used as sensitizers. Photoreduction of UP to the radical anion (UP- ) was detected by electron spin resonance when UP/AH/membrane mixtures were irradiated anaerobically. Aerobic irradiation resulted in a strong AH- -stimulation of lipid peroxidation, H2 O2 formation, and OH- generation (detected with 2-deoxyribose (DOR) and the spin trap 5,5-dimethyl-l-pyrroline-N-oxide). Use of diagnostic agents (e.g. catalase, desferrioxamine, mannitol) revealed that OH- is involved in light-stimulated DOR oxidation, but not in lipid peroxidation. Similar irradiation in the presence of PP resulted in far greater lipid peroxidation than observed with UP, but less DOR oxidation, and insignificant accumulation of H2 O2 . This suggests that photoreduction of membrane-bound PP is less efficient, possibly due to hindered access of AH- . 相似文献
4.
PROOXIDANT and ANTIOXIDANT EFFECTS OF ASCORBATE ON PHOTOSENSITIZED PEROXIDATION OF LIPIDS IN ERYTHROCYTE MEMBRANES 总被引:1,自引:0,他引:1
Albert W. Girotti James P. Thomas John E. Jordan 《Photochemistry and photobiology》1985,41(3):267-276
Abstract— Continuous blue light irradiation of resealed erythrocyte ghosts at 37°C in the presence of uroporphyrin or protoporphyrin results in 1 O2 -mediated (azide inhibitable) lipid peroxidation and membrane lysis. Lipid peroxidation was assessed by thiobarbituric acid reactivity and by quantitation of total hydroperoxides, while lysis was measured in terms of trappedglucose–6-P release. Low concentrations of ascorbate, AH- (e.g. 0.5 m M ). present at the start of irradiation, significantly enhanced the rates of lysis and peroxidation, whereas relatively high concentrations of AH- (e.g. 15 m M ) inhibited both processes. By way of contrast. AH- produced only a dose-dependent inhibition of the photoinactivation of lysozyme, added as an extramembranous target. No significant AH- induced lipid peroxidation was observed in dark or light controls, plus porphyrin or minus porphyrin, respectively. Stimulation of peroxidation and lysis by low levels of AH- was enhanced by added Fe(III), abolished by EDTA. but unaffected by catalase or superoxide dismutase. A plausible explanation for these results is as follows. At low concentrations of AH- prooxidant activity is favored. Redox metal-mediated breakdown of photoperoxides occurs, which tends to amplify lipid peroxidation. Neither O2 - nor H2 O2 appears to be involved. At significantly high concentrations, AH- acts predominantly as an antioxidant by intercepting 1 O2 and/or sensitizer triplet, or by scavenging free radical intermediates of lipid peroxidation. 相似文献
5.
Wolf Krauss † Gabriele Schiebel Dagmar Eberl Achim Hager 《Photochemistry and photobiology》1987,45(S1):837-844
Abstract— Irradiation (λmax 447 nm; 58.5 W m-2 ) of a microsomal membrane fraction of corn coleoptiles for 5 min in the presence of the in vivo concentration of riboflavin inactivates the tonoplast-type H+ -ATPase. This inhibition is O2 -dependent, is enhanced in D2 O and suppressed by NaN3 , indicating participation of singlet molecular oxygen in the inactivating mechanism. Besides singlet oxygen, the superoxide anion (O2 - ) is generated during irradiation, which obviously has no effect on the H+ -pumping activity. However, in the presence of superoxide dismutase (SOD), O2 - is transformed into H2 O2 which causes an additional strong inhibition of H+ . ATPase activity. This inhibition can be increased by ethylenediaminetetraacetic acid (EDTA), which is known to be an electron donor of the excited flavin molecule. In contrast, catalase prevents the H2 O2 -mediated photoinactivation of the H+ -ATPase. The light dependent inactivation of H+ -transport does not occur if reduced glutathion (GSH) is added prior to or after irradiation. These results indicate that the blue light mediated inhibition of the H+ -ATPase is mediated by singlet oxygen and H2 O2 which oxidize essential SH-groups of the enzyme into disulfides. Reduction of the formed disulfides by GSH restores the activity of the enzyme. 相似文献
6.
Abstract In the presence of the photosensitizer riboflavin at high fluence rates a photoproduct, most probably H2 O2 , is formed which causes negative phototaxis in the colorless flagellate Polytomella magna . The aim of this study was to find out whether H2 O2 is produced in a type I or II reaction. As has been shown, 1 O2 quenchers either do not influence the photodynamic action of riboflavin (furfuryl ethanol, DPBF, l -histidine, crocetin) or show slight quenching effects only at very high concentrations ≧ 10−2 M (DABCO, DMF, imidazole). D2 O is toxic to P. magna even in 1:1 and 1:2 mixtures with H2 O. On the other hand, the quenching effect of 1,4-benzoquinone, highly indicative for the type I pathway, is more than two orders of magnitude stronger than the one of the above mentioned 1 O2 quenchers. The results suggest that H2 O2 is produced in a type I reaction. Superoxide does not seem to be involved since superoxide dismutase does not diminish the photodynamic effect of riboflavin. 相似文献
7.
LUMIFLAVIN-SENSITIZED PHOTOOXYGENATION OF INDOLE 总被引:1,自引:0,他引:1
Abstract— The lumiflavin-sensitized photooxygenation of indole in aqueous solutions has been investigated by means of steady light photolysis and flash photolysis. The semiquinone of lumiflavin and the half-oxidized radical of indole were formed by the reaction between triplet lumiflavin and indole (3.7 times 109 M -1 s-1 ). The semiquinone anion radical of lumiflavin reacted with oxygen to form superoxide radical. The triplet state of lumiflavin also reacted with oxygen forming singlet oxygen, 1 O2 . But the reaction between 1 O2 and indole (7 times 107 M_l s_1 ; estimated from steady light photolysis using Rose Bengal as a sensitizer) was far less efficient than the reaction between indole and triplet lumiflavin. The quantum yield of the lumiflavin-sensitized photooxygenation of dilute indole via radical processes was much higher than that via 1 O2 processes, though appreciable 1 O2 was formed. 相似文献
8.
Dolores J. Fatur † Richard H. C. San † Allan J. Davison † Hans F. Stich † 《Photochemistry and photobiology》1987,45(3):413-420
Abstract— Maximum chemiluminescence in a system containing 6-hydroxydopamine (6-OHDA) and H2 O2 required the addition of Fe2+ :EDTA, oxygen, and lucigenin. In this system luminescence was strongly inhibited by catalase (91% inhibition) or 50 m M mannitol (83%), whereas superoxide dismutase or ascorbate did not significantly change the reaction rate. In the absence of lucigenin, 50 m M mannitol (78%), catalase (76%), or ascorbate (73%) inhibited strongly, while superoxide dismutase inhibited by 60%. Removing EDTA from the lucigenin-containing system caused a 79% decrease in luminescence, while the substitution of desferoxamine for EDTA decreased luminescence by 55%. In the presence of desferoxamine plus EDTA the luminescence increased by 30% in comparison with that seen with EDTA alone. Luminescence in the system containing 6-hydroxydopamine, H2 O2 , Fe2+ :EDTA and lucigenin required the presence of oxygen (93% inhibition anaerobically), consistent with a mechanism involving reductive oxygenation of the lucigenin. It is concluded that luminescence in the presence of lucigenin involves a substantial contribution from H2 O2 and Fe2+ mediated by a mannitol-sensitive intermediate (conceivably Fenton-derived hydroxyl radicals). In the absence of lucigenin, superoxide and an ascorbate-labile component are additional important participants in the process. 相似文献
9.
MECHANISM OF PHOTOSENSITIZATION BY PHEOPHORBIDE a STUDIED BY PHOTOHEMOLYSIS OF ERYTHROCYTES AND ELECTRON spIN RESONANCE SPECTROSCOPY 总被引:1,自引:0,他引:1
Abstract Phcophorbide a (PPa), a causal substance of food intoxication, when excited by exposure to light wavelengths of over 600 nm, caused the photohemolysis of goat erythrocytes in proportion to the incubation time of the cells. The addition of N-3 , an effective scavenger of 1 O2 , to the medium markedly inhibited the hemolysis of erythrocytes in a concentration-dependent manner, whereas the addition of superoxide dismutase (SOD) and catalase, inhibitors of O- 2 and H2 O2 generation, respectively, to the medium had little effect on it.
Methods for converting1 O2 to a nitroxide radical by 2,2,6,6-tetramethyl-4-piperidone (TMPD) and for trapping O- 2 and OH by 5,5-dimethyl-l-pyrroline-A'-oxide (DMPO) were employed to observe directly these activated oxygens by electron spin resonance (ESR). The methods provided evidence that only 1 O2 , was produced by PPa, which was excited by light wavelengths of over 600 nm. Both the addition of N3 to the solution and the removal of oxygen from the solution inhibited the generation of 1 O2 .
These results led us to conclude that1 O2 was mainly responsible for the hemolysis of erythrocytes by photoexcited PPa. 相似文献
Methods for converting
These results led us to conclude that
10.
HYDROGEN PEROXIDE INDUCED RESISTANCE TO BROAD-SPECTRUM NEAR-ULTRAVIOLET LIGHT(300–400 nm) INACTIVATION IN Escherichia coli 总被引:5,自引:0,他引:5
Abstract— Strains of Escherichia coli carrying the four possible combinations of the alleles nur, nur+ , uvrAb, and uvrA + were either untreated or pretreated with a sublethal dose of H2 02 prior to inactivation with NUV radiation. Pretreated cells exhibited a greater resistance to NUV than did untreated cells. Pretreatment with H2 O2 did not induce resistance to FUV radiation. The induction of resistance to NUV inactivation by H2 O2 pretreatment apparently leads to protection against the damage caused by NUV radiation. Although pretreatment of cells with H2 02 leads to resistance of such cells to inactivation by H2 O2 and NUV, survival of H2 O2 treated bacteriophage PI cml clr100 is not enhanced when assayed on H2 O2 pretreated E. coli host cells. 相似文献
11.
William E. Antholine Tadeusz Sarna † Roger C. Sealy Balaraman Kalyanaraman Glen D. Shields David H. Petering 《Photochemistry and photobiology》1985,41(4):393-399
Abstract— Irradiation of bleomycin with light (λ > 320 nm) leads to a decrease in absorbance at 290 nm, which is suppressed by metal ions and by oxygen. Light-induced oxygen consumption is diminished by the enzymes superoxide dismutase and catalase, implying that toxic reduced species of oxygen (O2 and H2 O2 ) are formed during irradiation. Spin-trapping measurements with 5,5-dimethyl-1-pyrroline-1-oxide and 2-methyl-2-nitrosopropane demonstrated that hydroxyl radical and methyl radical adducts also are generated in the system. In addition, direct ESR measurements have shown that methyl radicals are produced during irradiation of bleomycin solutions at low temperatures, together with radicals probably derived from the bithiazole moiety of the bleomycin. The latter are also produced from irradiation of the model compound bithia. Radical production is diminished by complexation of bleomycin with metal ions. 相似文献
12.
The photooxidation of N,N -diethylhydroxylamine (DEHA) by Rose Bengal (RB) has been investigated in micellar and nonmicellar aqueous solutions. We measured the quantum yield of oxygen consumption forming H2 O2 and monitored two intermediates, the superoxide and diethylnitroxide radicals. When the pH was vaned, the quantum yield of oxidation remained constant for 6 < pH < 10.5, decreased in acidic pH, and increased considerably in NaOH solution; these changes could be attributed to the protonation and dissociation processes of the >N-OH moiety of DEHA. The formation of diethylnitroxide radical was enhanced by superoxide dismutase or strong alkaline solution. Around neutral pH, the oxidation proceeded mainly via electron transfer from DEHA to the RB triplet ( k q = 107 M -1 s-1 ) with little 1 O2 participation ( kq < 105 M -1 s-1 ). However, when RB was incorporated into micelles in alkaline solution, the contribution of the singlet oxygen pathway increased at the expense of electron transfer, which was inhibited by the less polar micellar environment. Dark autoxidation of DEHA was accelerated by heavy metal impurities and increased very strongly in NaOH solution. 相似文献
13.
M. Delmelle 《Photochemistry and photobiology》1978,27(6):731-734
Abstract— All -trans retinal is dissolved in alcohols and illuminated at 365 nm in the presence of a singlet oxygen acceptor, 2,5-dimethylfuran. Illumination produces the photosensitized oxidation of the acceptor which is measured by the disappearance of its 215 nm absorption band. A kinetic study is carried out and βDMF is 1.6 × 10- -4 M . The quantum yield of 1 O2 production from the light-excited retinal is estimated to 0.096. The retinal sensitized photooxidation of dimethylfuran is inhibited by a 1 O2 quencher, 1,4-diazabicyclo(2,2,2)-octane, and enhanced by deuteration of the solvent. Deuterated solvents are known to increase 1 O2 lifetime.
The production of1 O2 from retinal is briefly discussed in relation to the damage which may be induced by light in the visual cells. 相似文献
The production of
14.
Abstract —In vivo participation of singlet excited oxygen (1 O2 , 1 Δ9) in the photodynamic inactivation and induction of genetic changes (gene conversion) in acridine orange-sensitized yeast cells was investigated by using N3 - , an efficient 1 O2 quencher, and D2 O, a known agent for the enhancement of the lifetime of 1 O2 . The addition of N3 - protected the cells from both photodynamic actions. From an analysis of the concentration-dependent protection, about 80% of the induction of the genetic change is explainable on the basis of 1 O2 mechanism. The quantitative estimation of the N3 - protection in the inactivation was not possible because of the sigmoidal nature of the inactivation curve. The replacement of H2 O with D2 O during illumination was effective in enhancing the photodynamic inactivation but almost completely ineffective for the gene conversion induction. The deuterium effect with the cell system was clearly not as large as would be expected from in vitro experiments. This, however, could be explained from the kinetic consideration that natural quenchers of l O2 in the cell would mask the deuterium effect. By experiments with different cell stages it was demonstrated that these two modifying effects were dependent on the intracellular reaction environment. The conclusion is that 1 O2 must be the major intermediate responsible for the photodynamic actions in acridine orangesensitized yeast cells. 相似文献
15.
The influence of singlet oxygen (1 O2 ), generated by red light irradiation of oxygenated suspensions containing aluminium phthalocyanine sulphonate, on the membrane bound enzyme β-hydroxybutyrate dehydrogenase was investigated. The inactivation rates were measured using a spectrophotometry assay which involves disruption of the mitochondria. A novel NMR assay was also used to measure the activity of the enzyme in intact mitochondria. Relatively high inactivation rates of around 109 M −1 s−1 were observed in H2 O buffer, and rates in D2 O were a factor of 1.7 faster. Significant differences in enzyme inactivation rates by 1 O2 were observed, not only between disrupted and intact mitochondria but also between the NMR assay results and the spectrophotometric assay results. The results indicate the value of a specific assay which does not require the disruption of the biological system. 相似文献
16.
Abstract— –In the light, isolated spinach thylakoids consumed O2 in the presence of methylviologen, and ascorbate was found to interact with this reaction in various ways. Chelating-resin was used to remove metal impurities from the assay medium. Ascorbate diminished the H2 02 pool in resin-untreated solutions, while in resin-treated solutions ascorbate had no effect on H2 O2 concentrations. A Fenton catalyst (Fe-EDTA) increased O2 uptake in the presence of ascorbate and decreased the amount of O2 recovered by catalase. Ascorbate tripled the rate of the methylviologen-mediated Mehler reaction, and the O2 consumed was liberated to 50% of its original concentration by catalase. Superoxide dismutase reversed the effects of ascorbate on the Mehler reaction rates. These results indicate that ascorbate can stimulate Mehler reactions indirectly by promoting a Fenton-type reaction as well as stimulating Mehler reactions directly by reducing 2O2 - to 2H2 O2 . The promotion of a Fenton-type reaction by ascorbate appears to be the cause of H2 O2 depletion in resin-untreated solutions. 相似文献
17.
Abstract— A novel method for the determination of singlet oxygen reaction rate constants is described and applied to studies of cyclohexadiene in methanol and gelatins in H2 O and D2 O. The technique uses tris (2,2'-bipyridine) ruthenium(II) dication (Ru(bipy)32+ ) as both singlet oxygen sensitizer and in situ oxygen concentration monitor during irradiation of sealed samples. Because of the high efficiency with which the luminescence of Ru(bipy)3 2+* can be detected, and the fact that emission lifetimes are used, the method offers some advantages over those previously described. The advantages and disadvantages of the method are discussed. A rate constant of 2.1 (±0.3) x 106 mol-1 dm3 s-1 has been determined for the reaction of 1 O2 with cyclohexadiene in methanol. For two different photographic gelatins the sums of reaction and quenching rate constants are 2.0 (±0.4) x 106 and 3.1 (±2.0) x 105 mol-1 dm3 s-1 ; for swine skin gelatin this value is 3.9 (±2.4) × 105 mol-1 dm3 s-1 . Chemical reaction, rather than physical quenching, is the dominant reaction route for gelatins and 1 O2 . 相似文献
18.
Abstract— A very efficient quenching of singlet oxygen (1 O2 ) by N3 - ions has been applied to the determination of rate constants of reactions of 1 O2 with various substrates (A). This determination has been made possible by choosing experimental conditions which give simple competition between N3 - and A for 1 O2 formed in the steady state irradiation of convenient sensitizing dye (S). The consumption of oxygen by the substrate, as followed with an oxygen analyzer, decreases in the presence of low concentrations of N3 - . Using neutral air saturated aqueous solutions containing the dye phenosafranine + A and varying concentrations of N3 - , the 1 O2 rate constants for reactions with biological substrates and some radiation protective agents have been determined. 相似文献
19.
Abstract— In many biological systems, the role of O2 - in hydroxylation and toxic processes was assumed to be due to the formation of OH radicals. The Haber-Weiss reaction (Haber and Weiss, 1934)—(H2 O2 + O2 - → OH + OH- + O2 ) was suggested as the origin of this activity.
In this study it is shown that this reaction pathway is too slow, and that OH is probably formed from the reaction of complexed superoxide with H2 O2 or/and from the reduction of Fe(III), bound to biological compounds, by O2 - ; the reduced Fe(II) can then react with H2 O2 as a Fenton reagent, to yield OH.
It is also shown that singlet oxygen cannot be formed in these biological systems neither from the dismutation of OJ nor from the reaction of O2 - with OH. Singlet oxygen may be formed from the reduction of metal complexes by O2 - . 相似文献
In this study it is shown that this reaction pathway is too slow, and that OH is probably formed from the reaction of complexed superoxide with H
It is also shown that singlet oxygen cannot be formed in these biological systems neither from the dismutation of OJ nor from the reaction of O
20.
EFFECT OF INTENSITY AND WAVELENGTH OF FLUORESCENT LIGHT ON CHROMOSOME DAMAGE IN CULTURED MOUSE CELLS 总被引:2,自引:0,他引:2
Ram Parshad Katherine K. Sanford William G. Taylor Robert E. Tarone Gary M. Jones Anne E. Baeck 《Photochemistry and photobiology》1979,29(5):971-975
Abstract—A single 3- to 20-hr exposure of line NCTC 9266 mouse cells to cool-white fluorescent light (4.6 W/m2 ) produces chromatid breaks and exchanges. The effective wavelength is in the visible range and coincides with the mercury emission peak at 405 nm. Increasing light intensity from 4.6 W to 15.3 W/m2 for 20 h causes a concomitant increase both in production of chromosome damage and formation of hydrogen peroxide (H2 O2 ) in the serum-free medium. Cells washed free of medium and illuminated in saline for 3 h show chromosome damage to the same extent as cells illuminated in culture medium. Addition of catalase during the exposure period of 3 h eliminates the light-induced damage. We conclude that the light-induced chromatid breaks and exchanges result from H2 O2 production within the cell and that exogenous catalase can enter the cell and prevent the damage. 相似文献