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PubMed1985

Anthracycline-induced oxygen consumption and oxidative damage in rat liver microsomes are not necessarily coupled. A study with 8 structurally related anthracyclines.

The stimulative effect of 8 anthracyclines (the parent compounds daunorubicin and doxorubicin and 6 structurally closely related anthracyclines) on the production of thiobarbituric acid (TBA)-reactive material was investigated in liver microsomes. Except for daunorubicinone and doxorubicinone, all derivatives stimulated NADPH-dependent production of TBA-reactive material. Doxorubicinone had no effect, daunorubicinone inhibited TBA-reactivity at concentrations up to 50 microM. However, the latter two compounds stimulated oxygen consumption in the presence of EDTA to a degree comparable to that induced by the parent compounds. Since the oxygen uptake under these circumstances represents redox cycling of the drugs, apparently redox cycling and production of TBA-reactive material were not coupled for these compounds. Spectral measurements showed no decisive role for interaction with free iron (Fe3+) ions in the non-coupling of redox cycling and production of TBA reactive material. Evidence for a role of bound iron ions was not obtained. It is discussed that for the aglycones oxygen consumption and production of TBA reactive material might be non-coupled through their different interaction with microsomal RNA.

Animals↗
PubMed1986

Deoxyhypusine hydroxylase from rat testis. Partial purification and characterization.

Deoxyhypusine hydroxylase, the enzyme that catalyzes the formation of hypusine from deoxyhypusine in eukaryotic initiation factor 4D, has been partially purified from rat testis. The partially purified enzyme requires only the addition of certain sulfhydryl compounds for catalytic activity, dithiothreitol being the most effective. Its lack of dependency on the alpha-keto acid-dependent dioxygenase cofactors, Fe2+, alpha-ketoglutarate, and ascorbic acid, its failure to decarboxylate stoichiometrically alpha-ketoglutarate with deoxyhypusine hydroxylation, and its strong and specific inhibition by Fe2+ all suggest a catalytic mechanism of this enzyme unlike that of the prolyl and lysyl hydroxylases.

Animals↗
PubMed1993

Evaluation of activity of putative superoxide dismutase mimics. Direct analysis by stopped-flow kinetics.

By stopped-flow kinetic analysis, we have directly evaluated the superoxide dismutase (SOD) activity of a number of organic nitroxides and iron- and manganese-based complexes that have been attributed with having SOD activity based upon competition experiments with cytochrome c. In 60 mM HEPES buffer, pH 8.1, or 50 mM potassium phosphate buffer, pH 7.8, Mn(II) and manganese complexes of desferal had no detectable SOD activity by stopped-flow analysis (catalytic rate constant (kcat) < 10(5.5) M-1 s-1), whereas Mn(II) and manganese complexes of desferal inhibited the reduction of cytochrome c by superoxide generated by the xanthine/xanthine oxidase system. Fe(II)-N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (FeTPEN) was eight times more active than Fe(III)-tris[N-(2-pyridylmethyl)-2-aminoethyl]amine(Fe-TPAA) in the cytochrome c assay, but only FeTPAA catalyzed the first-order decay of superoxide (kcat = 2.15 x 10(6) M-1 s-1) by stopped-flow. Fe(III)-tetrakis(4-N-methylpyridyl)porphine (FeTMPP) was active at low micromolar concentrations in both the cytochrome c and stopped-flow assays. At high micromolar concentrations, the organic nitroxides 2,2,6,6-tetramethylpiperidin-1-yloxy (TEMPO) and 4-hydroxy-2,2,6,6-tetramethylpiperidin-1-yloxy (TEMPOL) were inhibitory in the cytochrome c assay, but showed no detectable SOD activity by stopped-flow. None of the tested compounds inhibited xanthine oxidase activity as shown by the measurement of urate production. Under the conditions of the cytochrome c assay, FeTPEN, TEMPO, and TEMPOL oxidized reduced cytochrome c which rationalizes the false positives for these compounds in this assay. The inhibitory activities of Mn(II) and the manganese desferal complexes in the cytochrome c assay appear to be due to a stoichiometric, not catalytic, reaction with superoxide as catalytic amounts of these agents do not induce a first-order decay of superoxide as shown by stopped-flow.

Cyclic N-Oxides↗
PubMed2004

Monitoring cell therapy using iron oxide MR contrast agents.

Given the remarkable progress that has recently been obtained in animal studies, the clinical use of stem and progenitor cells to correct or replace defective cell populations may soon become a reality. In order to develop effective cell therapies, the location and distribution of these cells must be determined in a non-invasive manner. Magnetic resonance (MR) tracking of magnetically labeled cells following transplantation or transfusion may fulfill this requirement. Indeed, a series of recent studies indicate that MRI cell tracking has great potential for further evaluation and optimization of cell therapy. Due to its biocompatibility and strong effects on T2(*) relaxation, iron oxide nanoparticles appear to be the contrast agent of choice, and several methods now exist to shuttle sufficient amount of these compounds into cells. Most of the tracking work has been carried out in disease models of the central nervous system, but, recently, the infarcted heart has also received attention. With its excellent spatial resolution and the ability to track labeled cells over prolonged periods of time, MR monitoring of cell therapy is likely to become an important technique in the foreseeable future.

Animals↗
PubMed2003

[Octanhydroxamate of iron: synthesis, analysis and investigation of stability].

Hydroxamic acids are found as chelates in plants, as metabolites of bacteria and funges. Some aerobic microorganisms synthesize hydroxamic acids, which transmit iron from environment to the cells of the plants. Fourteen hydroxamic acids were synthesized and their interaction with iron (II and III) was investigated. The purpose of this investigation was synthesis of hydroxamic acids, creation of stable iron chelate with one of these acids, preparation of the methods of analysis, investigation of the stability of chelate and application for prophylaxis and treatment of iron deficiency anemia. We used octanhydroxamic acid for creation of chelate with iron. The synthesis of this acid was the cheapest and compound with iron appeared stable. Iron chelates after acid hydrolysis were analyzed by quantity of iron (9.8-12.3%). We used complexometric titration method with dinatrium salt of ethylendiamintetraacetic acid without indication for quantitative analysis. Iron (II) chelate is less stable, therefore, we used Fe (III) octanhydroxamate for further investigations. Preliminary trials with rabbits confirm rapid assimilation of iron (III) chelate from gastrointestinal tract and activation of erythropoiesis.

Anemia, Iron-Deficiency↗
PubMed2006

A novel peroxy radical based oxidative stressing system for ranking the oxidizability of drug substances.

A novel oxidative stressing system is described which generates high levels of peroxy radicals in solution at room temperature, without the use of azonitrile initiators. The oxidative stressing system is composed of a 10% solution of Tween 80 in water to which FeCl3 x 6H2O is added. The Tween 80 acts as a solubilizing agent for drug compounds, and also contains substantial amounts of organic hydroperoxides. It is shown that the Fe III/ Fe II couple operates on the hydroperoxide concentration to effectively generate new peroxy radicals, which then propagate in the Tween 80 solution. Key features of the Tween 80/Fe III system are investigated, and the oxidizability of seven known compounds and ten developmental compounds are examined. Relative reaction rates span a 300-fold range, from benzoic acid (nonreactive, defined as <0.5% reacted per day) to Vitamin D3 (7% reacted per hour). Oxidizability "rankings" thus generated are shown to agree well with azonitrile initiated oxidative stress. The potential for general correlations between this type of oxidizability data and actual oxidative performance in LFC and solid oral dosage forms is discussed.

Chlorides↗
PubMed1988

Adriamycin and its iron(III) and copper(II) complexes. Glutathione-induced dissociation; cytochrome c oxidase inactivation and protection; binding to cardiolipin.

Some reactions of adriamycin (doxorubicin) and its Fe3+ and Cu2+ complexes were investigated with a view to understanding the mechanisms by which metal ion-adriamycin complexes damage cellular components. The ability of adriamycin in the presence of Cu2+ to inactivate the mitochondrial enzyme cytochrome c oxidase was effectively prevented by physiologic levels of glutathione. This result is explained by the observation that glutathione reacts with the Cu2+-adriamycin complex to produce free adriamycin. As sulfhydryl compounds are, in contrast, known to promote Fe3+-adriamycin-induced damage to cellular components, these results suggest that the response of a metal ion-adriamycin system to the presence of sulfhydryl compounds may be indicative of whether or not Cu2+-adriamycin is the damaging species. The partition of adriamycin into the octanol phase of an octanol-water two-phase system was greatly enhanced by the presence of cardiolipin. This result can be explained by the formation of a strong adriamycin-cardiolipin complex in the octanol phase which is one-half formed at an adriamycin concentration of 6 microM.

Cardiolipins↗
PubMed2004

Determination of quantum yields for the photolysis of Fe(III)-hydroxo complexes in aqueous solution using a novel kinetic method.

The determination of quantum yields for the photolysis of Fe(III)-hydroxo complexes is important for the quantitative investigation of hydroxyl radical (*OH) production, not only in a natural water body, but also in the photo-Fenton process. A novel kinetic method, using a *OH probe compound, was established for the determination of the quantum yields in this study. The method was based on measuring the pseudo-first-order rate constant of the photodecomposition of dimethylsulfoxide (DMSO) in which DMSO and its primary products scavenged the *OH at an identical rate. The preliminary experiments for the photodecomposition kinetics supported the suitability of DMSOs as a probe compound for determining quantum yields. The individual quantum yields for the photolysis of the monomeric Fe(III) complexes, in the wavelength range 240-380 nm, were determined by the photodecomposition kinetics of the hydroxyl radical (*OH) probe compound (DMSO). The determined values of the individual quantum yields were 0.046+/-0.00052 for Fe3+ (H2O)6 (hexaaquo ion) and 0.69+/-0.025 for Fe(OH)2+ (H2O)5 (hydroxypentaaquo ion) at 254 nm, and showed decreasing values with increasing wavelength, in the ranges of 240-380 nm. The quantum yields between 240 and 280 nm were newly reported in this study, and the values obtained between 280 and 380 nm were in good agreement with the literature values.

Dimethyl Sulfoxide↗
PubMed2005

Absence of a detectable intermediate in the compound I formation of horseradish peroxidase at ambient temperature.

A microsecond-resolved absorption spectrometer was developed to investigate the elementary steps in hydrogen peroxide (H(2)O(2)) activation reaction of horseradish peroxidase (HRP) at ambient temperature. The kinetic absorption spectra of HRP upon the mixing with various concentrations of H(2)O(2) (0.5-3 mm) were monitored in the time range from 50 to 300 mus. The time-resolved spectra in the Soret region possessed isosbestic points that were close to those between the resting state and compound I. The kinetic changes in the Soret absorbance could be well fitted by a single exponential function. Accordingly, no distinct spectrum of the putative intermediate between the resting state and compound I was identified. These results were consistent with the proposal that the O-O bond activation in heme peroxidases is promoted by the imidazolium form of the distal histidine that exists only transiently. It was estimated that the rate constant for the breakage of the O-O bond in H(2)O(2) by HRP is significantly faster than 1 x 10(4) s(-1).

Chemical Phenomena↗
PubMed1996

Toxicity of iron oxides and metabolites of benzo[a]pyrene alone or in combination in cells culture and identification by laser microprobe mass spectrometry.

The goal of the gas-phase studies of well-characterized transition-metal systems is to enhance our understanding of the chemistry and sometimes of the toxic, carcinogenic effects of transition metal oxide clusters and compounds. The analysis of inorganic solids by time of flight laser microprobe mass spectrometry (TOF-LMMS) shows the formation of clusters in the mass spectra which can be used for the identification of inorganic particles. First, we have applied non-resonance ionization (delta = 226 nm) or resonant ionization (delta = 293.7 nm) of iron to study the non stoichiometric Fe1-xO, Fe3O4, Fe2O3 compounds in positive mode by TOF-LMMS. The positive mass spectra are characterized by many differences between the clusters detected and their intensities. Then, we have analysed the benzo[a]pyrene (BaP), the 1-hydroxbenzo[a]pyrene (1-OH-BaP) and the 3-hydroxybenzo[a]pyrene (3-OH-BaP) of TOF-LMMS and by Fourier Transform Irons Cyclotron Resonance Mass Spectrometry (FT-ICR-MS). It is possible to distinguish these different compounds by their respective fingerprint. Later on, we have studied toxic effects of iron oxides (Hematite Fe2O3 and Magnetite Fe3O4), benzo[a]pyrene (BaP) and Pyrene, alone or in combination. The LC50 was appreciated by colony-forming cell culture method. Cells were observed by electron microscopy and the valence of particles was analysed by TOF-LMMS. With Fe2O3 we have observed a significant decrease (20%) at higher concentration (0.5 mmol/l) and smaller quantities of BaP were highly toxic. The association of BaP at the LC10 dose (0.05 mumol/l) with growing doses of Fe2O3 or Fe3O4 (0.0125; 0.025; 0.05; 0.1; 0.2 mmol/l), appeared to increase the toxic effect of BaP 3 to 4 times. These results suggest that Fe2O3 and Fe3O4 alone are not very toxic but the association of one of these compounds with BaP increases the toxicity of the latter. On the other hand, TOF-LMMS seems to show a metabolization of iron oxide into reduced form. But, it is necessary to raise the ambiguity about the iron which is always in the cells present. For that purpose, studies with iron oxides enriched by 54Fe isotope have begun.

Benzo(a)pyrene↗
PubMed2003

Short-term inhalation of particulate transition metals has little effect on the electrocardiograms of dogs having preexisting cardiac abnormalities.

There is growing epidemiological evidence for statistical associations between increases in air pollution, especially particulate matter, and increases in cardiovascular morbidity and mortality. Laboratory studies have shown that transition metals contribute strongly to the effects of high lung doses of model particles on changes in the electrocardiograms of animals. The present study evaluated the effects of short-term inhalation exposure to respirable particles of specific oxide and sulfate forms of transition metals on heart rate and the electrocardiogram of old dogs having preexisting cardiac abnormalities. Conscious beagle dogs were exposed by oral inhalation for 3 h on each of 3 successive days to aerosols of manganese, nickel, vanadium, iron, and copper oxides, and nickel and vanadium sulfates as single compounds at concentrations of 0.05 mg/m(3). Electrocardiograms were recorded and evaluated for exposure-related changes in heart rate, heart rate variability, and abnormalities of waveforms. Although the electrocardiograms of this population of dogs having potential age and cardiovascular susceptibility factors reflected their underlying clinical abnormalities, no significant effect of exposure to the transition metal aerosols was observed.

Administration, Inhalation↗
PubMed2001

Enterobactin: the characteristic catecholate siderophore of Enterobacteriaceae is produced by Streptomyces species.(1).

Enterobactin is described in the literature as the typical iron-chelating compound (siderophore) produced by bacteria of the family Enterobacteriaceae. In the course of a HPLC with diode array detection screening programme for detection of novel secondary metabolites, enterobactin, its biosynthetic precursor 2,3-dihydroxy-N-benzoylserine and its linear dimer and trimer condensation products were found to be produced by two Streptomyces strains besides the trihydroxamate-type siderophores desferri-ferrioxamine B and E.

Chromatography, High Pressure Liquid↗
PubMed1996

In vivo biological activity of antioxidative aminothiazole derivatives.

For the development of novel antioxidants having therapeutic utility, a new series of condensed 4- and 5-aminothiazole derivatives has been synthesized using simple methods. Condensed 4-aminothiazoles were prepared by the reaction of alpha-bromolactams with thioamides in ethanol and 5-aminothiazole derivatives were obtained by the treatment of 3-(acylamino)lactams with a thiating agent such as phosphorous pentasulfide and Lawesson's reagent in pyridine. In vitro assay of the condensed 5-aminothiazole derivatives showed them to be potent inhibitors of lipid peroxidation. In order to evaluate these compounds in an in vivo system, we devised a simple and reproducible method in which the inhibition of characteristic behaviors induced by spinal injection of FeCl2 was expressed numerically. Compounds having strong in vitro activity protected the central nervous system form injury caused by iron-dependent lipid peroxidation. The results suggest that the in vivo assay developed in this study should be useful as a screening method for antioxidants and also that condensed 5-aminothiazole derivatives are promising candidates for the treatment of traumatic and ischemic injury of the central nervous system.

Animals↗
PubMed2003

Synthesis, structure, and spectroscopy of phenylacetylenylene rods incorporating meso-substituted dipyrrin ligands.

The synthesis, structure, and spectroscopic characterization of a series of phenylacetylenylene rodlike molecules containing dipyrromethene (dipyrrin) ligands are described. The combination of the phenylacetylenylene groups with the porphyrinogenic dipyrrin moieties results in a rich absorption spectroscopy for these compounds, although the fluorescence of the phenylacetylenylene moiety is quenched by presence of the dipyrrin chelator. The Cu(2+) and Fe(3+) complexes of these ligands have been prepared and three of these compounds have been structurally characterized by using single-crystal X-ray diffraction. Unlike other octahedral metal-dipyrrin complexes described to date, one of the iron complexes demonstrates ideal threefold symmetry in the solid-state. The elongated structure and high symmetry of these complexes suggests the use of these meso-substituted phenylacetylenylene ligands as an interesting class of extended, branched molecules for the construction of supramolecular architectures.

Acetylene↗
PubMed2001

Carbon monoxide adducts of KatG and KatG(S315T) as probes of the heme site and isoniazid binding.

KatG, the catalase peroxidase from Mycobacterium tuberculosis, is important in the activation of the antitubercular drug, isoniazid. About 50% of isoniazid-resistant clinical isolates contain a mutation in KatG wherein the serine at position 315 is substituted with threonine, KatG(S315T). The heme pockets of KatG and KatG(S315T) and their interactions with isoniazid are probed using resonance Raman (rR) spectroscopy to characterize their ferrous CO complexes. Three vibrational modes, C-O and Fe-C stretching and Fe-CO bending, are assigned using 12CO and 13CO isotope shifts. Two conformers are observed for KatG-CO and KatG(S315T)-CO. Resonance Raman features assigned to form I are consistent with it having a neutral proximal histidine ligand and the Fe-C-O moiety hydrogen bonded to a distal residue. The nu(C-O) band for form I is sharp, consistent with a conformationally homogeneous Fe-CO unit. Form II also has a neutral proximal histidine ligand but is not hydrogen bonded. This appears to result in a conformationally disordered Fe-CO unit, as evidenced by a comparatively broad C-O stretching band. The 13CO-sensitive bands assigned to form II are predominant in the KatG(S315T)-CO rR spectrum. Isoniazid binding is apparent from the resonance Raman signatures of both WT KatG-CO and KatG(S315T)-CO. Moreover, isoniazid binding elicits an increase in the form I population of wild-type KatG-CO while having little, if any, effect on the already low population of form I of KatG(S315T)-CO. Since oxyKatG (compound III) also contains a low-spin diatomic ligand-heme adduct (heme-O2), it is reasonable to suggest that it too would exist as a mixture of conformers. Because the small form I population of KatG(S315T)-CO correlates with its inability to activate INH, we hypothesize that form I plays a role in INH activation.

Amino Acid Substitution↗
PubMed2003

Antioxidant and free radical scavenging activity of isoflavone metabolites.

1. Soy isoflavones have been extensively studied because of their possible health-promoting effects. Genistein and daidzein, the major isoflavone aglycones, have received most attention; however, they undergo extensive metabolism in the gut and liver, which might affect their biological properties. 2. The antioxidant activity, free radical-scavenging properties and selected cellular effects of the isoflavone metabolites equol, 8-hydroxydaidzein, O-desmethylangiolensin, and 1,3,5 trihydroxybenzene were investigated in comparison with their parent aglycones, genistein and daidzein. 3. Electron spin resonance spectroscopy indicated that 8-hydroxydaidzein was the most potent scavenger of hydroxyl and superoxide anion radicals. Isoflavone metabolites also exhibited higher antioxidant activity than parent compounds in standard antioxidant (FRAP and TEAC) assays. However, for the suppression of nitric oxide production by activated macrophages, genistein showed the highest potency, followed by equol and daidzein. 4. The metabolism of isoflavones affects their free radical scavenging and antioxidant properties, and their cellular activity, but the effects are complex.

Animals↗
PubMed1987

Artifacts caused by cosmetics in MR imaging of the head.

Cosmetics can produce severe distortion of the orbital contents in MR imaging. This distortion, typical of compounds that exhibit a permanent magnetic moment, results from iron oxide in the pigments used to produce dark shades of makeup. In general, the artifact created by cosmetics does not interfere with interpreting routine head scans. However, if the orbital contents are the subject of clinical concern, the images may then be rendered nondiagnostic. The artifact created by the makeup is propagated along the frequency-encoding axis of the images.

Cosmetics↗
PubMed2005

Transformation of carbon tetrachloride by bisulfide treated goethite, hematite, magnetite, and kaolinite.

This study investigated the transformation of carbon tetrachloride (CT) by goethite, hematite, magnetite, and kaolinite treated with bisulfide to form coatings of iron monosulfide (FeS) and other Fe(II) species. These coatings contribute to abiotic natural attenuation in anaerobic environments. Batch kinetic experiments were performed under anoxic conditions at pH 8.0. Surface-area-normalized pseudo-first-order rate constants for CT transformation did not differ significantly for the three HS- treated iron oxides, but the rate of CT transformation by bisulfide-treated kaolinite was significantly lower, most likely due to kaolinite's lower iron content. The yield of chloroform (CF) from CT transformation was typically approximately 1%. There was negligible or only slight adsorption of several natural organic matter (NOM) model compounds to the surface of HS- treated goethite, and these compounds had no influence on CT transformation rate constants or CF yields. Juglone, on the other hand, adsorbed to a greater extent, and also significantly influenced the CF yield, increasing it by a factor of approximately 20 for HS- treated hematite. We speculate that juglone or its HS- addition product adsorbed to the mineral surface and acted as a hydrogen atom donor that reacted with the trichloromethyl radical intermediate, increasing the CF yield.

Adsorption↗