首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
A range of nitrogen-containing compounds (alkyl amines, piperazines, cyclohexylamines and nitrogen heterocyclics) were investigated for generation of hydrogen peroxide from dopamine and detection by peroxyoxalate chemiluminescence. Imidazole, ethyleneurea and allantoin among the nitrogen heterocyclic compounds tested generated hydrogen peroxide from dopamine following incubation at 60°C, pH 9.5–10.5, for 0–30 min. Imidazole was the most effective for generation of hydrogen peroxide, but imidazole derivatives with a primary amine side chain (histamine) or thiol (ethylenethiourea) were not effective. The presence of a ketone group (ethyleneurea, allantoin) did not hinder the reaction. Under optimal conditions (30 min incubation, 50 mmol/L imidazole) 10.5 nmol of dopamine could be detected. The cyclohexylamines tested produced low amounts of hydrogen peroxide (0.09–2.74% of light intensity with imidazole), and the piperazines and the alkyl amines tested produced no detectable hydrogen peroxide. Imidazole reacts with the phenolic groups of dopamine in a different manner from monoamine oxidase, and a reagent containing imidazole, ethyleneurea or allantoin was useful for non-enzymatic detection of dopamine by peroxyoxalate chemiluminescence.© John Wiley & Sons, Ltd.  相似文献   

2.
A series of diaryl and bis(4-styrylphenyl) oxalates with electron-donating substituents or fluorescent moieties were subjected to the peroxyoxalate chemiluminescence (PO-CL) reaction, some of which were found to behave in a unprecedented manner. The reaction of bis(p-methyoxyphenyl) oxalate, as a representative example, emits light due not only to the emission from the externally added excited fluorophore, but also from the presumable excimer of p-methoxyphenol. Also, during the reaction of the bis(4-styrylphenyl) oxalates, the emission based on the fluorescence as well as the excimer of the eliminating group were observed. These experimental results suggest that such emitting species would be formed by an intra- and intermolecular electronic interaction with a high-energy intermediate, such as a dioxetanone.  相似文献   

3.
The preparation of a fluorescent labelled oligonucleotide and its photographic detection by peroxyoxalate chemiluminescence (PO-CL) are described. Fluorescent labelling of an oligonucleotide (15-mer) was performed with naphthalene-2,3-dicarboxaldehyde to give an N-substituted 1-cyanobenz[f]isoindole (CBI) derivative (CBI-15-mer). For the photographic detection of CBI-15-mer, the bis(2,6-difluorophenyl) oxalate (DFPO)-dimethyl phthalate (DMP) system was selected to obtain a long-lived CL emission. After optimizing the conditions for the CL reaction, the system was applied to the photographic detection, and as little as 250 fmol per spot of CBI-15-mer on a membrane were detected as a visible spot with an instant photographic film. © 1998 John Wiley & Sons, Ltd.  相似文献   

4.
This paper describes a novel high-performance liquid chromatographic (HPLC) method for the determination of aromatic compounds with peroxyoxalate chemiluminescence (PO-CL ) detection following on-line UV irradiation. Aromatic compounds were UV irradiated (254 nm, 15 W) to generate hydrogen peroxide, which was determined via PO-CL detection using a mixture of bis(2,4,6-trichlorophenyl)oxalate (aryloxalate) and 2,4,6,8-tetrathiomorpholinopyrimido[5,4-d]pyrimidine (fluorophore) as a post-column CL reagent. Generation of hydrogen peroxide from aromatic compounds was confirmed using a flow injection analysis (FIA) system incorporating an enzyme column reactor immobilized with catalase. The conditions for UV irradiation were optimized using benzene and monosubstituted benzenes (phenol, benzaldehyde, nitrobenzene and N,N-dimethylaniline) by an HPLC system to evaluate the analytical performance of the proposed system. The detection limits for benzene and monosubstituted benzenes were in the range 2.1-124 pmol/injection at signal:noise (S:N) ratio = 3. Monocyclic and polycyclic hydrocarbons were also employed to investigate their CL properties. The possibility of PO-CL detection for a wide variety of aromatic compounds was shown for the first time.  相似文献   

5.
《Luminescence》2003,18(4):203-206
A method for reactivation of inactivated horseradish peroxidase (HRP) was studied and exploited in an assay for hydrogen peroxide (H2O2). Addition of imidazole into a mobile phase made continuous determination of hydrogen peroxide (H2O2) possible by micro?ow injection based on horseradish‐catalysed luminol chemiluminescence. For reproducible determination of H2O2 with HRP, the inactivation of HRP via protonation of the active sites of HRP caused by reaction with H2O2 must be avoided. We successfully reactivated protonated HRP (inactive HRP) with exogenous imidazole in the mobile phase of the micro?ow injection system. The imidazole successfully removed the attached proton from the inactive sites of the HRP. This assay was reproducible (within‐run reproducibility, CV = 4.0%) and the detection limit for H2O2 was 5 pmol. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

6.
An isoluminol assay is utilized for the detection. of hydrogen peroxide and lipid hydroperoxides in biological samples. The combination of this assay as a post-column detection for HPLC avoids interference of antioxidants and enables characterization of hydroperoxides at picomole levels. Two useful HPLC conditions for the separation of hydrogen peroxide, lipid hydroperoxides, antioxidants, and unoxidized lipids are described.  相似文献   

7.
We report the first detailed study of the characteristics of an octahydro‐Schiff base derivative as a new luminophor in the peroxyoxalate chemiluminescence (POCL) system. The effect of reagents on this new POCL system was investigated. In addition, the response surface methodology was used for evaluating the relative significance of variables in this POCL system, establishing models and determining optimal conditions. The quenching effect of some cations and compounds such as Cu2+, Fe3+, Hg2+, imidazole, histidine and cholesterol on an optimized POCL reaction were studied. The dynamic ranges were up to approximaterly 100 and 175 × 10?6 M for Cu2+ and cholesterol respectively. The detection limits were 3.3 × 10?6 m and 2.58 × 10?6 m for Cu2+ and histidine, respectively. In all cases the relative standard deviations were 4–5% (n = 4). Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

8.
The overproduction of hydrogen peroxide is implicated in the progress of numerous life-threatening diseases and there is a great need for the development of contrast agents that can detect hydrogen peroxide in vivo. In this communication, we present a new contrast agent for hydrogen peroxide, termed peroxalate micelles, which detect hydrogen peroxide through chemiluminescence, and have the physical/chemical properties needed for in vivo imaging applications. The peroxalate micelles are composed of amphiphilic peroxalate based copolymers and the fluorescent dye rubrene, they have a ‘stealth’ polyethylene glycol (PEG) corona to evade macrophage phagocytosis, and a diameter of 33 nm to enhance extravasation into permeable tissues. The peroxalate micelles can detect nanomolar concentrations of hydrogen peroxide (>50 nM) and thus have the sensitivity needed to detect physiological concentrations of hydrogen peroxide. We anticipate numerous applications of the peroxalate micelles for in vivo imaging of hydrogen peroxide, given their high sensitivity, small size, and biocompatible PEG corona.  相似文献   

9.
The chemiluminescence of luminol (3-aminophthalhydrazide) with H2O2 has been used to quantify endogenous amounts of H2O2 in plant tissues. The reaction is linear over at least three orders of magnitude between 10?5 and 10?2M H2O2. Interference by coloured compounds in the crude extract is calibrated by a purification step with Dowex AG 1-X8. The extract is calibrated with an internal H2O2 standard, and the specificity verified by H2O2 purging with catalase. The minimum delectability for H2O2 of this assay is at least 1 ng, corresponding to 0.1–1 g fresh material. Data are presented for the levels of H2O2 in potatoes after treatment with oxygen and ethylene, in tomatoes before and after ripening and in untreated germinating castor beans as well as in beans treated with aminotriazol to inhibit catalase activity. Though data using the titanium test are generally confirmed, the method presented here has the advantage of higher sensitivity and specificity.  相似文献   

10.
Relativistic density functional calculations of uranyl complexes with alcohols were carried out to study how phenolic and aliphatic hydroxyl groups of humic substances may contribute to uranyl complexation by humic substances. According to recent experimental work, blocking of phenolic OH groups decreases the loading capacity, but has no effect on the key geometric parameters of uranyl humate complexes. This can be understood on the basis of our calculations which showed uranium-oxygen distances to be very similar for complexes with rather different types of O-donor ligands, with average U-Oeq ∼ 237 pm for fivefold coordinated uranyl (VI) complexes, both for O and OH functional groups. Uranyl complexation by alcohol moieties seems unlikely at environmental conditions as a high pH is required for the deprotonation of these groups; we confirm an alternative complexation mechanism that overcomes the ligand deprotonation problem. Similarities in structures and energetic suggest that complexes of both aliphatic and phenolic alcoholates may well contribute in comparable fashion to the complexation of uranyl by humic acids.  相似文献   

11.
We explored the behaviour of a series of phenolic acids used as enhancers or inhibitors of luminol chemiluminescence by three different methods to determine if behaviour was associated with phenolic acid structure and redox character. All the phenolic acids inhibited chemiluminescence when hexacyanoferrate(III) was reacted with the phenolic acids before adding luminol. The redox character of these compounds was clearly related to structure. When hexacyanoferrate(III)-luminol-O2 chemiluminescence was initiated by phenolic acid-luminol mixtures some phenolic acids behaved as enhancers of chemiluminescence, and others as inhibitors. We propose a mechanism to explain these findings. We found direct relationships between the redox character of the phenolic acids and the enhancement or inhibition of the chemiluminescence of the luminol–H2O2–peroxidase system and we propose mechanism to explain these phenomena.  相似文献   

12.
The reactivity of flow-injection (FI)-horseradish peroxidase (HRP)-catalysed imidazole chemiluminescence (CL) was studied for continuous determination of hydrogen peroxide (H(2)O(2)) and serum glucose with immobilized glucose oxidase. Light emission by the HRP-catalysed imidazole CL was obtained when immobilized HRP, alkaline imidazole (in Tricine solution, pH 9.3) and H(2)O(2) were reacted at room temperature. The optimal pH for the CL reaction was 9.3 and the optimal concentration of imidazole was 100 micromol/L. When no imidazole was added, the light intensity of the same H(2)O(2) specimen decreased to a level that could not be quantitatively determined. The spectrum of the light emitted by imidazole CL was in the range 400-600 nm with a peak at 500 nm. The calibration equation for determination of H(2)O(2) was y = 9860x(2) + 3830x + 11,700, where y = light intensity (RLU) and x = concentration of H(2)O(2) (micromol/L). The detection limit of H(2)O(2) was 5 pmol, and the reproducibility of the H(2)O(2) assay was 2.3% of the coefficient of variation (H(2)O(2) 48 micromol/L, n = 13). The CL method was successfully applied to assay glucose after on-line generation of H(2)O(2) with the immobilized glucose oxidase column, resulting in good reproducibility (CV = 3.3% and 1.0% for the standard glucose and the control serum, respectively).  相似文献   

13.
The oxidation of catechol in neutral and slightly alkaline aqueous solutions (pH 7-9.6) by excess hydrogen peroxide (0.002-0.09 mol/L) in the presence of Co(II) (2.10(-7)-2.10(-5) mol/L) is accompanied by abrupt formation of red purple colouration, which is subsequently decolourized within 1 h. The electron spectra of the reaction mixture are characterized by a broad band covering the whole visible range (400-700 nm), with maximum at 485 nm. The reaction is initiated by catechol oxidation to its semiquinone radical and further to 1,2-benzoquinone. By nucleophilic addition of hydrogen peroxide into the p-position of benzoquinone C=O groups, hydroperoxide intermediates are formed, which decompose to hydroxylated 1,4-benzoquinones. It was confirmed by MS spectroscopy that monohydroxy-, dihydroxy- and tetrahydroxy-1,4-benzoquinone are formed as intermediate products. As final products of catechol decomposition, muconic acid, its hydroxy- and dihydroxy-derivatives and crotonic acid were identified. In the micellar environment of hexadecyltrimethylammonium bromide the decomposition rate of catechol is three times faster, due to micellar catalysis, and is accompanied by chemiluminescence (CL) emission, with maxima at 500 and 640 nm and a quantum yield of 1 x 10(-4). The CL of catechol can be further sensitized by a factor of 8 (maximum) with the aid of intramicellar energy transfer to fluorescein.  相似文献   

14.
The chemiluminescent oxidation of luminol and an isoluminol cortisol conjugate (ABICOR) by hydrogen peroxide has been studied in cetyltrimethylammonium bromide (CTAB) reversed micelles in octane-chloroform (1 : 1). The maximum chemiluminescence intensity of both compounds is dependent on the initial concentrations of the H2O2 and substrates, the pH value of the micelle polar phase and the H2O/CTAB ratio. The optimum pH ranged from 8.5 to 9.5. Under comparable conditions, the chemiluminescence intensity for luminol was 15-fold higher than for the ABI-COR conjugate. A mechanism of oxidation of the substrates in reversed micelles is proposed and the possible mechanisms of inhibition by the substrate and oxidant is discussed.  相似文献   

15.
A novel effect of the inhibition of the decomposition of amino acids to carbonates on addition of imidazole (HIm) to a reacting system containing equimolar amounts of copper and zinc metal powders, an amino acid [glycine (Hgly), aspartic acid (H2Asp) or glycylglycine (H2gg)] (1:1:2) and excess hydrogen peroxide (H2O2) resulting in formation of a mixed metal mixed ligand peroxo complex compound was observed, because in the absence of imidazole the corresponding reaction system yields only a mixed metal peroxo carbonate. For the resulting complex compounds, the homogeneity, i.e. [Cu(Zn)(O2 2–)(Gly)2(HIm)(H2O)], [Cu(Zn)(O2 2–)(Asp)(HIm)(H2O)2] or [Cu(Zn)2(O2 2–)2(gg)(HIm)(H2O)4], molecular formula, presence of peroxo group and coordination environment were established by combined physicochemical evidence from elemental and thermogravimetric analysis in air and argon atmospheres, electron spin resonance and electronic and IR spectral data. It is noteworthy to mention that the corresponding carboxylic acids of the above-mentioned amino acids, i.e. acetic and succinic acids, either do not decompose to carbonates in the absence of imidazole or form novel homogeneous peroxo mixed metal mixed ligand complex compounds as described above in the presence of imidazole. This suggests an important and significant mutual influence (in vitro) of biologically active chromophores like peroxo ions, imidazole and amino groups in the above-mentioned chemical reactions containing bioactive metals such as copper and zinc.  相似文献   

16.
In the present work, the generation mechanism of reactive oxygen species (ROS) on calcium peroxide (CaO(2)) was studied. A very intense chemiluminescence (CL) signal was observed when adding an aqueous solution of luminol or 2-methyl-6-(4-methoxyphenyl)-3,7-dihydroimidazo[1,2alpha]-pyrazin-3-one hydrochloride (MCLA) to a suspension of CaO(2). The ROS released on CaO(2) were thought to be oxidizing agents leading to CL, and were characterized by CL, UV-visible (UV-vis) spectra and the effective scavengers of the special ROS. From experimental results, the hydroxyl (.OH) and superoxide (.O(2) (-)) radicals were suggested to exist on the surface of CaO(2). A reaction scheme for the formation of the ROS on CaO(2) was also proposed and discussed. Of more interest was the finding that the CaO(2) which released the .OH and .O(2) (-) on the surface exhibited good transition properties compared with alkaline-earth metal peroxides of the same group (MgO(2), BaO(2)).  相似文献   

17.
Many papers in the literature have described complex effects of flavonoids and other polyphenols on cells in culture. In this paper we show that hydroxytyrosol, delphinidin chloride and rosmarinic acid are unstable in three commonly-used cell culture media (Dulbecco’s modified Eagle’s medium (DMEM), RPMI 1640 (RPMI) and Minimal Essential Medium Eagle (MEM)) and undergo rapid oxidation to generate H2O2. This may have confounded some previous studies on the cellular effects of these compounds. By contrast, apigenin, curcumin, hesperetin, naringenin, resveratrol and tyrosol did not generate significant H2O2 levels in these media. Nevertheless, curcumin and, to a lesser extent, resveratrol (but not tyrosol) were also unstable in DMEM, so the absence of detectable H2O2 production by a compound in cell culture media should not be equated to stability of that compound. Compound instability and generation of H2O2 must be taken into account in interpreting effects of phenolic compounds on cells in culture.  相似文献   

18.
Effects of hydrogen peroxide on morphological characteristics, proliferation index, and menadione-dependent lucigenin-enhanced chemiluminescence of C6 glioma cells were studied. It was established that H2O2 at 5 × 10?7?1 × 10?8 M concentrations acted as a regulator of morphological and functional properties of astrocytes, inducing their reactivation, which is manifested as cell body hypertrophy and an increase of proliferative activity and menadione-induced production of superoxide anion radicals (O 2 ?? ). Cytodestructive action of hydrogen peroxide at a concentration higher than 1 × 10?6 M on C6 glioma cells shows itself as a decrease of their proliferation index and the ability to generate O 2 ?? under the effect of menadione. Use of lipopolysaccharide B as a functional stimulator has shown that H2O2 modifies signaling pathways leading to an increase of mitotic activity of C6 glioma cells and decreases the yield of lucigenin-dependent chemiluminescence of astrocytes under the action of menadione to the level of control values.  相似文献   

19.
An isoluminol assay is utilized for the detection of hydrogen peroxide and lipid hydroperoxides in biological samples. The combination of this assay as a post-column detection for HPLC avoids interference of antioxidants and enables characterization of hydroperoxides at picomole levels. Two useful HPLC conditions for the separation of hydrogen peroxide, lipid hydroperoxides, antioxidants, and unoxidized lipids are described.  相似文献   

20.
Hydrogen peroxide amplifies the chemiluminescence in the oxidation of luminol by sodium hypochlorite. A linear relationship between concentration of hydrogen peroxide and light intensity was found in the concentration range 5 × 10?8?7.5 × 10?6 mol/l. At 7.5 × 10?6 mol/l H2O2 the chemiluminescence is amplified 550—fold. The chemiluminescence spectra of these reactions have a wavelength maximum at 431 nm independent of the concentration of hydrogen peroxide. The results indicate that hydrogen peroxide is a necessary component in the chemiluminescent oxidation of the luminol by sodium hypochlorite.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号