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PubMed2002

Synthesis, structure, properties, and phosphatase-like activity of the first heterodinuclear Fe(III)Mn(II) complex with the unsymmetric ligand H(2)BPBPMP as a model for the PAP in sweet potato.

The new heterodinuclear mixed valence complex [Fe(III)Mn(II)(BPBPMP)(OAc)(2)]ClO(4) (1) with the unsymmetrical N(5)O(2) donor ligand 2-bis[((2-pyridylmethyl)-aminomethyl)-6-((2-hydroxybenzyl)(2-pyridylmethyl))-aminomethyl]-4-methylphenol (H(2)BPBPMP) has been synthesized and characterized. Compound 1 crystallizes in the monoclinic system, space group P2(1)/c, and has an Fe(III)Mn(II)(mu-phenoxo)-bis(mu-carboxylato) core. Two quasireversible electron transfers at -870 and +440 mV versus Fc/Fc(+) corresponding to the Fe(II)Mn(II)/Fe(III)Mn(II) and Fe(III)Mn(II)/Fe(III)Mn(III) couples, respectively, appear in the cyclic voltammogram. The dinuclear Fe(III)Mn(II) center has weakly antiferromagnetic coupling with J = -6.8 cm(-1) and g = 1.93. The (57)Fe Mössbauer spectrum exhibits a single doublet, delta = 0.48 mm s(-1) and DeltaE(Q) = 1.04 mm s(-1) for the high spin Fe(III) ion. Phosphatase-like activity at pH 6.7 with the substrate 2,4-bis(dinitrophenyl)phosphate reveals saturation kinetics with the following Michaelis-Menten constants: K(m) = 2.103 mM, V(max) = 1.803 x 10(-5) mM s(-1), and k(cat) = 4.51 x 10(-4) s(-1).

Acid Phosphatase↗
PubMed2004

A comparative study of the effects of chloride, sulfate and nitrate ions on the rates of decomposition of H2O2 and organic compounds by Fe(II)/H2O2 and Fe(III)/H2O2.

The effects of chloride, nitrate, perchlorate and sulfate ions on the rates of the decomposition of hydrogen peroxide and the oxidation of organic compounds by the Fenton's process have been investigated. Experiments were conducted in a batch reactor, in the dark at pH < or = 3.0 and at 25 degrees C. Data obtained from Fe(II)/H2O2 experiments with [Fe(II)]0/[H2O2]0 > or = 2 mol mol(-1), showed that the rates of reaction between Fe(II) and H2O2 followed the order SO4(2-) > ClO4(-) = NO3- = Cl-. For the Fe(III)/H2O2 process, identical rates were obtained in the presence of nitrate and perchlorate, whereas the presence of sulfate or chloride markedly decreased the rates of decomposition of H2O2 by Fe(III) and the rates of oxidation of atrazine ([atrazine]0 = 0.83 microM), 4-nitrophenol ([4-NP]0 = 1 mM) and acetic acid ([acetic acid]0 = 2 mM). These inhibitory effects have been attributed to a decrease of the rate of generation of hydroxyl radicals resulting from the formation of Fe(III) complexes and the formation of less reactive (SO4(*-)) or much less reactive (Cl2(*-)) inorganic radicals.

Acetic Acid↗
PubMed1981

Effect of siderophores on virulence of Neisseria gonorrhoeae.

The virulence of Neisseria gonorrhoeae for chicken embryos can be modified in a predictable manner by the addition of microbial siderophores to the inoculum. "Meningobactin" and "gonobactin," siderophores isolated from iron-limited cultures of meningococci and gonococci, respectively, enhance the virulence of the relatively avirulent colony type 3 (T3) organisms, but have essentially no effect on the virulence of T1 organisms. Both of these compounds were found previously to stimulate in vitro growth of the pathogenic Neisseria spp. under conditions made iron limiting by the addition of conalbumin, the transferrin counterpart of chickens. Similarly, ferrated schizokinen and arthrobactin, both dihydroxamate siderophores which stimulated growth in iron-limited conditions in vitro, also enhanced virulence of T3 organisms, whereas desferrioxamine B mesylate (Desferal), a trihydroxamate previously shown to be inhibitory in vitro, decreased the virulence of the T1 colony form. This was due to the iron-binding function of the molecule, as the iron-saturated form, ferrioxamine B mesylate, did not affect virulence. An additional trihydroxamate siderophore, ferrichrome A, which was inactive on Neisseria spp. in either the deferri- or ferrated forms in vitro, likewise did not affect virulence in the chicken embryo model. The neisserial siderophores were more effective than the other microbial siderophores in enhancing virulence of T3 gonococci. The results add to the evidence that the ability to acquire iron is an important determinant of virulence.

Animals↗
PubMed1993

Inhibitory effect of dioxopiperazine compounds on malondialdehyde formation induced by doxorubicin in rat liver mitochondria in vitro.

The isolated rat liver mitochondria were used in vitro to study the effect of doxorubicin on lipid peroxidation. We found that NADH-dependent mitochondrial peroxidation, measured by thiobarbituric acid (TBA) method, was stimulated to fourfold by doxorubicin (50 mumol.L-1). The addition of Fe3+ produced a significant increase of malondialdehyde (MDA) formation induced by doxorubicin. Doxorubicin enhanced the peroxidation of lipids in liver mitochondria through enzymatic mechanism especially in the presence of Fe3+. Probimane, bimolane, dexrazoxane (dioxopiperazine compounds), and edetic acid (EDTA) inhibited the formation of MDA in doxorubicin or doxorubicin+FeCl3 systems in a concentration-dependent manner. The inhibitory rates of MDA formation by probimane at the concentrations of 0.01, 0.05, 0.1, and 0.25 mmol.L-1 were 27.80%, 25.19%, 47.80%, and 59.77% respectively; bimolane were 21.04%, 25.55%, 24.83%, and 54.13%; dexrazoxane were 11.29%, 20.68%, 34.94%, and 58.65%; EDTA were 57.52%, 55.67%, 61.62%, and 63.16% in Dox and FeCl3 system. The inhibitory rates of MDA formation by probimane at concentration 0.01, 0.05, 0.1, and 0.25 mmol.L-1 were 19.27, 39.02, 59.60, and 58.63% respectively; bimolane were 6.10, 17.19, 41.58, and 53.22%; dexrazoxane were 27.24, 33.26, 58.21, and 59.11%; EDTA were 63.76, 67.43, 61.68, and 63.27% respectively in Dox system. These results suggested that protection against cardiotoxicity of doxorubicin afforded by probimane, bimolane, and dexrazoxane may be related to their ability to combine with the complex iron so that the iron was no longer able to take part in free radical reactions.

Animals↗
PubMed1975

Mu-induced polarity in the Escherichia coli K-12 ent gene cluster: evidence for a gene (entG) involved in the biosynthesis of enterochelin.

A strain of Escherichia coli K-12 has been isolated that carries a Mu bacteriophage-induced mutation in the ent gene cluster. Nutritional tests together with examination of the compounds accumulated by the mutant strain indicated that the mutant was blocked both in the synthesis of 2,3-dihydroxy-benzoate and its subsequent conversion into enterochelin. Enzymic complementation assays of the mutant with several mutants each affected in one of the ent genes showed that the Mu-induced mutant was entA-, entB-, entC+, entD+, entE+, and entF+. Since the mutant produced the entD, entE, and entF gene products but was unable to produce enterochelin from 2,3-dihydroxybenzoate, it must therefore be affected in an additional protein concerned with this conversion. It is therefore postulated that the Mu-induced mutation affects a previously unrecognized gene, entG. Genetic experiments indicate that the mutation in strain AN462 which affects the three ent genes is the result of a single insertion of Mu in the ent gene cluster. This polarity mutant therefore provides evidence that three of the ent genes are part of an operon.

Alcohol Oxidoreductases↗
PubMed2004

[Preparation and feasibility of superparamagnetic dextran iron oxide nanoparticles as gene carrier].

BACKGROUND & OBJECTIVE: Application of magnetic nano- particles as gene carrier in gene therapy of tumor has developed quickly. To obtain a new type non-viral gene introduction and therapy system,which is convenient,and can drive target gene to express highly and stably,this study was designed to explore the preparation of superparamagnetic dextran iron oxide nanoparticles(SDION),and the feasibility of SDION used as gene carrier in vitro. METHODS: SDION were prepared by chemical co-precipitation,separated by gel filtration chromatography on Sephacryl S-300HR,and centrifugation techniques,characterized by transmission electron microscopy,laser scattering system,and vibrating sample magnetometer signal processor. The green fluorescent protein-C2 (GFP-C2) plasmid was used as target gene. SDION-GFP- C2 compounds were synthesized by oxidation-reduction reaction. The connection rate of SDION and GFP-C2 was analyzed by agarose electrophoresis,and evaluated by measuring concentration of GFP in the supernatant after centrifugation. Liposome transfection was used as control,the efficiencies of SDION and liposome in transferring GFP gene into human bladder cancer BIU-87 cells were evaluated under fluorescence microscope in vitro. RESULTS: The diameter of SDION ranged from 3 nm to 8 nm, the effective diameter was 59.2 nm, and the saturation magnetization was 0.23 emu/g. After oxidized by sodium periodate of 10 mmol/L,and deoxidized by sodium hydride boron of 0.5 mol/L, SDION could connect with GFP in maximum degree,the transfection efficiency of SDION as gene carrier was about 45%, even higher than that of liposome (about 30%). CONCLUSION: SDION could connect with GFP plasmid by oxidation- reduction reaction,and success to transfer GFP gene into human bladder cancer BIU-87 cells in vitro.

Dextrans↗
PubMed2001

Monooxygenation mechanism by cytochrome p-450.

The substrate oxygenation mechanism by an ultimate species in monooxygenation by cytochrome P-450 (compound I) was investigated by the density functional theory method. An initial model compound was constructed from a structure obtained by 300-ps molecular dynamics simulation of compound I-formed P-450cam under physiologic conditions, and it consisted of porphine for protoporphyrin IX, S(-)-CH(3) for the side chain of Cys357 of the fifth ligand of heme, a methane molecule for the substrate, a heme iron, and an oxygen atom of the sixth ligand of heme. The results of the calculation revealed that the substrate oxygenation mechanism had four elementary processes, i.e., (1) formation of [FeOH](3+) and a substrate radical by hydrogen atom abstraction from the substrate caused by [FeO](3+), (2) rotation of the OH group of the sixth ligand of [FeOH](3+) produced by process 1, (3) substrate radical binding with the [FeOH](3+), and (4) elimination of the oxygenated substrate formed at the sixth ligand binding site. The rate-determining step is process 1, hydrogen atom abstraction from the substrate, and the activation energy was determined to be about 15 kcal/mol. For this reason, it is thought that this reaction occurs in vivo.

Binding Sites↗
PubMed2004

[The UV spectra of heterocyclic selenium compounds and metallic ions in ethanol solutions].

The UV spectra of heterocyclic selenium compounds and metallic ions in ethanol solutions were investigated in this paper. Heterocyclic selenium compounds included 4,5-benzopiazselenole (BP), anthra [1,2-c][1,2,5] selenadiazol-6,11-dione (AS), piazselenole (PS), 5-methyl-piazselenole (MP), 4,6-diBr-piazselenole (DBP) and 4,4-dipiazselenole (DP). Several important results were obtained: (1) The absorption wavelengthslambda of piazselenoles were bathochromic and their epsilon increased with the increased conjugative effect; (2) Sn(IV) enhanced the UV absorption of piazselenoles at higher frequencies with the ratio of nSn(IV)/nPS at 1; (3) The UV absorption of BP was obviously enhanced by Sn(IV), Cd(II), Cr(III), Sb(III), Fe(III), Fe(II) and Cu(II), while Zn(II) had little effect on the UV of BP; (4) The UV absorption of piazselenoles at higher frequencies was enhanced by Sn(IV), Cr(III) and Sb (III), and the peak of MP at 233 nm was blunt in MP-M solutions.

Antimony↗
PubMed2006

Oxidative renal tubular injuries induced by aminocarboxylate-type iron (III) coordination compounds as candidate renal carcinogens.

Oxidative renal tubular injuries and carcinogenesis induced by Fe(III)-nitrilotriacetate (NTA) and Fe(III)-ethylenediamine-N,N'-diacetate (EDDA) have been reported in rodent kidneys, but the identity of iron coordination structure essential for renal carcinogenesis, remains to be clarified. We compared renal tubular injuries caused by various low molecular weight aminocarboxylate type chelators with injuries due to NTA and EDDA. We found that Fe(III)-iminodiacetate (IDA), a novel iron-chelator, induced acute tubular injuries and lipid peroxidation to the same extent. We also prepared Fe(III)-IDA solutions at different pHs, and studied resultant oxidative injuries and physicochemical properties. The use of Fe(III)-IDA at pH 5.2, 6.2, and 7.2 resulted in renal tubular necrosis and apoptotic cell death, but neither tubular necrosis nor apoptosis was observed at pH 8.2. Spectrophotometric data suggested that Fe(III)-IDA had the same dimer structure from pH 6.2 to 7.2 as Fe(III)-NTA; but at a higher pH, iron polymerized and formed clusters. Fe(III)-IDA was crystallized, and this was confirmed by X-ray analysis and magnetic susceptibility measurements. These data indicated that Fe(III)-IDA possessed a linear mu-oxo bridged dinuclear iron (III) around neutral pH.

Animals↗
PubMed2007

Infrared multiphoton dissociation of the siderophore enterobactin and its Fe(III) complex. Influence of Fe(III) binding on dissociation kinetics and relative energetics.

The dissociation pathways of the siderophore enterobactin and its complex with Fe(III) were examined using infrared multiphoton dissociation (IRMPD). Under experimental conditions (pH = 3.5), both compounds' electrospray spectra exhibited exclusively singly-charged anions. The compositions of the dissociation products were characterized by accurate mass measurements using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The primary dissociation channel for both species was determined to be the loss of one serine group from the precursor molecules. To further investigate the influence of Fe(III) binding on the intramolecular interactions, dissociation kinetics and relative energetics for the loss of this serine group were determined using the focused radiation for gaseous multiphoton energy-transfer (FRAGMENT) method. From the kinetic data, it was found that enterobactin was approximately seven times more reactive than its Fe(III) complex over the range of laser intensities investigated. The relative activation energies, however, exhibited similar values, approximately 7 kcal.mol(-1). These results suggest that at pH = 3.5, Fe(III) interacts with only two of the three serine groups. The results from the present work are believed to be valuable for the characterization of novel siderophores as well as their associated metabolites and synthetic analogues.

Enterobactin↗
PubMed2004

Dissimilatory Fe(III) and Mn(IV) reduction.

Dissimilatory Fe(III) and Mn(IV) reduction has an important influence on the geochemistry of modern environments, and Fe(III)-reducing microorganisms, most notably those in the Geobacteraceae family, can play an important role in the bioremediation of subsurface environments contaminated with organic or metal contaminants. Microorganisms with the capacity to conserve energy from Fe(III) and Mn(IV) reduction are phylogenetically dispersed throughout the Bacteria and Archaea. The ability to oxidize hydrogen with the reduction of Fe(III) is a highly conserved characteristic of hyperthermophilic microorganisms and one Fe(III)-reducing Archaea grows at the highest temperature yet recorded for any organism. Fe(III)- and Mn(IV)-reducing microorganisms have the ability to oxidize a wide variety of organic compounds, often completely to carbon dioxide. Typical alternative electron acceptors for Fe(III) reducers include oxygen, nitrate, U(VI) and electrodes. Unlike other commonly considered electron acceptors, Fe(III) and Mn(IV) oxides, the most prevalent form of Fe(III) and Mn(IV) in most environments, are insoluble. Thus, Fe(III)- and Mn(IV)-reducing microorganisms face the dilemma of how to transfer electrons derived from central metabolism onto an insoluble, extracellular electron acceptor. Although microbiological and geochemical evidence suggests that Fe(III) reduction may have been the first form of microbial respiration, the capacity for Fe(III) reduction appears to have evolved several times as phylogenetically distinct Fe(III) reducers have different mechanisms for Fe(III) reduction. Geobacter species, which are representative of the family of Fe(III) reducers that predominate in a wide diversity of sedimentary environments, require direct contact with Fe(III) oxides in order to reduce them. In contrast, Shewanella and Geothrix species produce chelators that solubilize Fe(III) and release electron-shuttling compounds that transfer electrons from the cell surface to the surface of Fe(III) oxides not in direct contact with the cells. Electron transfer from the inner membrane to the outer membrane in Geobacter and Shewanella species appears to involve an electron transport chain of inner-membrane, periplasmic, and outer-membrane c-type cytochromes, but the cytochromes involved in these processes in the two organisms are different. In addition, Geobacter species specifically express flagella and pili during growth on Fe(III) and Mn(IV) oxides and are chemotactic to Fe(II) and Mn(II), which may lead Geobacter species to the oxides under anoxic conditions. The physiological characteristics of Geobacter species appear to explain why they have consistently been found to be the predominant Fe(III)- and Mn(IV)-reducing microorganisms in a variety of sedimentary environments. In comparison with other respiratory processes, the study of Fe(III) and Mn(IV) reduction is in its infancy, but genome-enabled approaches are rapidly advancing our understanding of this environmentally significant physiology.

Archaea↗
PubMed1994

Liver iron quantification: studies in aqueous iron solutions, iron overloaded rats, and patients with hereditary hemochromatosis.

For the noninvasive liver iron quantification by MRI in human iron overload diseases, fundamental proton relaxation mechanisms were studied in aqueous solutions with ferritin and other iron compounds, in experimentally iron overloaded rats, and in patients with iron overload diseases. MR-relaxation rates as a function of iron concentrations in the range of 0-7.5 mg Fe/g aqueous iron solutions, 0-5.4 mg Fe/g rat liver in vivo, and 0.16-4.9 mg Fe/g human liver in vivo were determined from multi- and sets of single-spin echo sequences (1.5 T imager). As predicted by theory, transverse relaxation rates (1/T2) in aqueous iron solutions, in liver tissue of rats, and in human liver tissue increased linearly with the iron concentration. A preliminary calibration for the liver iron quantification by MRI was performed from in vivo measurements of liver 1/T2-relaxation rates and liver iron quantification by atomic absorption spectroscopy in biopsies from 13 patients. With the single spin-echo method, precise in vivo liver iron quantification in humans also above 2.0 mg Fe/g liver tissue (T2 < 15 ms) should be accomplished on any imager with shortest spin-echo time available, at least TE < 20 ms.

Adult↗
PubMed2003

Antioxidant isoflavones in Osage orange, Maclura pomifera (Raf.) Schneid.

Recent findings that many human chronic diseases are associated with oxidative stresses have instigated the search for dietary antioxidants. Many phytochemicals, particularly phenolic compounds, have been found to possess strong antioxidant activity and reduce the risks of those diseases. Isoflavones, a special phenolic group found in soybean, have been found to act as antioxidants in some model systems. This study investigated the isoflavone content in a unique nonedible tree fruit, Osage orange [Maclura pomifera (Raf.) Schneid], and methods for the extraction, identification, and quantification of the two major isoflavones, osajin and pomiferin, were developed. The ethyl acetate extract contained 25.7% osajin and 36.2% pomiferin, and the two isoflavones were at 9.5 g kg(-1) of fresh Osage orange. Two model systems, FRAP and beta-CLAMS, were used to measure the antioxidant activity of these two isoflavones. Pomiferin was found to be a strong antioxidant in both systems, comparable to the antioxidant vitamins C and E and the synthetic antioxidant BHT. Osajin and the two soybean isoflavones (genistein and daidzein) showed no antioxidant activity. Although the Osage orange fruit is not a food source, it is considered to be safe and, therefore, a potentially good source of an antioxidant nutraceutical and functional food ingredient.

Acrolein↗
PubMed2005

MR techniques for in vivo molecular and cellular imaging.

MR-based molecular imaging is a science in infancy. Current clinical contrast agents are often geared toward the assessment of gross physiologic function, rather than targeting specific biochemical pathways. The development of specific targeted smart contrast agents for Food and Drug Administration approval or clinical trials has only begun. The fact that MR imaging can obtain images of extremely high resolution, coupled with its ability to simultaneously assess structure and function through the use of targeted contrast agents indicates that MR will play a pivotal role in clinical molecular imaging of the future. Many of the challenges that face MR imaging and spectroscopy are inherent to all modalities in the rapidly growing field of molecular imaging. The development of smart contrast agents to report on receptor function, and to monitor gene expression or the results of gene therapy in humans is paramount. These compounds need to undergo rigorous testing to be approved for clinical use: the assessment of acute toxicity, pharmacokinetics, long-term accumulation, and subsequent chronic effects. For receptor-targeted contrast agents, the degree of receptor occupancy and the intrinsic agonist or antagonist properties of the probe that may affect normal cellular function need to be determined to avoid undesired side effects. The particular problems that face MR imaging, those of sensitivity and target specificity, need to be overcome. Signal amplification achieved through high relaxivity contrast agents containing multiple paramagnetic centers, or of larger superparamagnetic particles, is the first step in this direction. The modulation of relaxivity through oligomerization, or other modifications that cause restriction of rotational motions, shows great promise for improving the discriminative powers of MR imaging, and may permit multiple targets to be assessed simultaneously. Moreover, the introduction of smart indicators that lead to changes in spectroscopic properties will allow further discrimination to be achieved through the implementation of chemical shift or spectroscopic imaging. The growing number of MR imaging applications in this rapidly expanding field point to a bright future for MR imaging in molecular imaging.

Cells↗
PubMed2003

Formation of volatile iodinated alkanes in soil: results from laboratory studies.

Volatile iodinated organic compounds play an important role in the tropospheric photochemical system, but the current knowledge of the known sources and sinks of these alkyl iodides is still incomplete. This paper describes a new source of alkyl iodides from the pedosphere. Different organic-rich soils and humic acid were investigated for their release of volatile organoiodides. Six volatile organoiodides, iodomethane, iodoethane, 1-iodopropane, 2-iodopropane, 1-iodobutane and 2-iodobutane were identified and their release rates were determined. We assume an abiotic reaction mechanism induced by the oxidation of organic matter by iron(III). The influence of iron(III), iodide and pH on the formation of alkyl iodides was investigated. Additionally, different organic substances regarded as monomeric constituents of humus were examined for the production of alkyl iodides. Two possible reaction pathways for the chemical formation of alkyl iodides are discussed. As humic acids and iron(III) are widespread in the terrestrial environment, and the concentration of iodide in soil is strongly enriched (compared to seawater), this soil source of naturally occurring organoiodides is suggested to contribute significantly to the input of iodine into the troposphere.

Ferric Compounds↗
PubMed2004

Bismercaptoethanediazacyclooctane as a N2S2 chelating agent and Cys-X-Cys mimic for Fe(NO) and Fe(NO)2.

The N-protonated bismercaptoethanediazacyclooctane serves as a bidentate dithiolate ligand to oxidized Fe(NO)(2) of Enemark-Feltam notation, E-F [Fe(NO)(2)],(9) mimicking Cys-X-Cys binding of Fe(NO)(2) to proteins or thio-biomolecules. The neutral compound is characterized by the well-known g = 2.03 EPR signal which is a hallmark of dinitrosyl iron complexes, DNIC's. The Fe(NO)(2) unit can be removed from the chelate by excess PhS(-), producing (PhS)(2)Fe(NO)(2)(-). Transfer of NO from Fe(H(+)bme-daco)(NO)(2) (nu(NO) = 1740, 1696 cm(-)(1)) to Fe(II) of [(bme-daco)Fe](2) yields the five-coordinate, square-pyramidal N(2)S(2)Fe(NO) (nu(NO) = 1649 cm(-)(1)), where NO is in the apical position. Its isotropic EPR signal at g = 2.05 is consistent with E-F [Fe(NO)](7) formulation. In excess NO, Roussin's red ester-type molecules are formed as dinuclear or tetranuclear species, [(micro-SRS)[Fe(2)(NO)(4)]](n)() (n =1, 2). These well-characterized molecules furnish reference points for positions and patterns in nu(NO) vibrational spectroscopy expected to be useful for in vivo studies of NO degradation of iron-sulfur clusters in ferredoxins.

Chelating Agents↗
PubMed1994

NaFe3+EDTA as a food fortificant: influence on zinc, calcium and copper metabolism in the rat.

The general acceptance of NaFe3+EDTA for food Fe fortification has been partly restricted by concern over the influence of EDTA on the metabolism of other nutritionally important trace elements and minerals. We have investigated the influence of NaFe3+EDTA, and of increasing dietary levels of Na2EDTA, on Zn, Cu and Ca metabolism in rats fed on Zn-sufficient and Zn-deficient soya-bean-isolate-based diets. With the Zn-deficient diets, changing the dietary Fe compound from FeSO4 to NaFe(3+)-EDTA significantly (P < 0.05) increased mean apparent Zn absorption from 50.2 to 67.4%, urinary Zn excretion from 2.0 to 4.0% of intake, and Zn retention from 48.2 to 63.4%. Increasing the dietary EDTA level to 1000 mg/kg further increased Zn absorption to 78.1%, urinary Zn excretion to 15.6% of intake and Zn retention to 62.5%. Increased Zn retention was accompanied by a significant increase in weight gain indicating that the extra Zn was available for normal metabolic processes. With rats fed on the Zn-sufficient diet, NaFe3+EDTA and Na2EDTA similarly increased the absorption, urinary excretion and retention of Zn but to a lesser extent. NaFe3+EDTA, however, had no influence on the absorption, urinary excretion and retention of Cu and Ca, and additional Na2EDTA caused only minor increases in Cu absorption and retention and in the urinary excretion of Ca. We conclude that using NaFe3+EDTA as a food fortificant would have no detrimental effect on the metabolism of Zn, Cu and Ca and, in some situations, could improve Zn absorption and retention from low-bioavailability diets.

Animals↗
PubMed2004

Enhanced remediation of carbon tetrachloride by Fe(II)-Fe(III) systems in the presence of copper ions.

The effect of Cu(II) ion on the dechlorination of carbon tetrachloride (CT) by Fe(II) associated with various iron oxides was investigated. Iron oxides including goethite, hematite, ferrihydrite and magnetite were selected as the model compounds. CT was dechlorinated to chloroform (CF) by 3 mM Fe(II) in iron oxide suspensions at pH 7.2. The dechlorination followed pseudo first-order kinetics and the pseudo first-order rate constants (k(obs)) were 0.048 h(-1), 0.0836 h(-1), 0.0609 h(-1) and 0.0144 h(-1) in goethite-, hematite-, ferrihydrite- and magnetite-amended systems, respectively. Addition of Cu(II) into systems increased the k(obs) for CT dechlorination significantly. A 3- to 120-fold increase in k(obs) relative to the systems without Cu(II) was observed when 0.5 mM Cu(II) was added to the Fe(II)-Fe(III) suspensions. The pH of the system is an important factor controlling the dechlorination rate of CT. The increase in concentrations of Fe(II) and iron oxides also enhanced the dechlorination efficiency and rate of CT. Moreover, a linear relationship between the k(obs) and Cu(II) concentration ranging between 0 and 0.4 mM was observed. Results obtained demonstrate the feasibility of using surface-bound iron species with Cu(III) for the detoxification of chlorinated solvents in the contaminated aquifers.

Carbon Tetrachloride↗