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PubMed1985

[Differential analysis of the binding forms of iron in various plant foodstuffs].

In fourteen plant foodstuffs of various composition a differentiation of iron contents according to water soluble, in ethylacetate extractable, in labile contents and iron(II) or Fe(III) species in the water extract are carried out by the spectrophotometric Ferrozine method. High water-soluble labile iron parts and high iron(II) contents were found in fruit, high complexed parts in the water extract and ethylacetate extractable iron contents in protein rich foodstuffs. The iron total contents are situated between 1 and 90 ppm, the water soluble parts amount to 6 up to 60% of the total content according to the foodstuffs.

Acetates↗
PubMed1989

Membrane damage in acute brain trauma.

Among a number of biochemical disturbances occurring in the acute phase of brain insults, the destruction of membrane phospholipids and its consequences on the function of membrane-bound proteins is likely to be one of the most important. In the cryogenic type of injury which is classically considered as a relevant animal model of brain contusive lesions in human traumatology, the initial attack of membranes could consist in a peroxidative damage triggered by blood ferrous compounds. This in turn would lead to an activation of phospholipase A2. As a consequence of phospholipid disruption a number of enzymes involved in energy production within the mitochondria are severely impaired. Nevertheless, the level of available ATP within the cell remains normal and even higher than normal. This paradoxical findings suggests that energy utilization is even more lowered than energy production. In fact, the Na+-K+-ATPase activity which normally utilizes approximately 70% of the total amount of cellular energy is severely reduced. We assume that Na+-K+-ATPase impairment is directly responsible for the retention of intracellular Na+ accompanied by osmotically driven water, though admittedly other biochemical disturbances, including tissue acidosis and liberation of excitatory amino-acids, would contribute to the same result. Lastly, a striking feature of these biochemical events is the early activation of those enzymes necessary for phospholipid resynthesis. This should mean that repair processes are at work immediately after the insult allowing resumption of Na+-K+-ATPase function, clearing up of brain edema and restoration of cation exchanges essential for brain work.

Animals↗
PubMed1999

Potential carcinogenicity of some transition metal ions.

Potential carcinogenicity of some transition metal ions was tested using a direct-current polarography method. The measurements were based on the reduction of tested compounds in an anhydrous solution using alpha-lipoic acid as the detection compound. The potential carcinogenicity was expressed in terms of the parameter tg alpha, which is known to directly correlate with the carcinogenicity of tested compounds. For the metal ions tested, tg alpha was found to decrease in the following sequence: Fe(III) > Pb(II) > V(IV) > Fe(II) > Mn(II) > Cu(II). Zero values of tg alpha were found for Cd(II) and Mn(III).

Animals↗
PubMed1994

Studies on lipid oxidation in fish phospholipid liposomes.

Fish phospholipid liposomes were prepared and used as an artificial membrane system to study factors influencing lipid oxidation. The extent of lipid oxidation was indexed by measuring the amount of thiobarbituric acid reactive substances (TBARS) produced. Fe2+, Fe3+, and Cu2+ were potent prooxidants in catalysing lipid oxidation. These metal ions induced lipid oxidation in a dose dependent manner. However, Zn2+, Ni2+, and Mn2+ did not significantly (p > 0.05) affect lipid oxidation at all the concentrations (1, 10, or 100 microM) studied. Morin, luteolin (flavonoids), butein (chalcone), tannic acid, ellagic acid (polyphenols), butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT) (synthetic antioxidants) were potent antioxidants (producing < 50% TBARS compared to control) of Fe(2+)-catalyzed lipid oxidation. Morin, luteolin, and butein possess two hydroxyl substituents, a C4 ketone structure and a 2-3 double bond, all of which contributed to their antioxidative potential. Fe2+ caused some losses of polyunsaturated fatty acids (PUFA), whereas tannic acid protected the oxidation of several of the PUFA including C 16:1 (Palmitoleic acid), C 18:3 (Linolenic acid), C 20:4 (Arachidonic acid), C 20:5 (Eicosapentaenoic acid), and C 22:6 (Docosahexaenoic acid).

Animals↗
PubMed1999

The application of ion chromatographic method for bioavailability and stability test of iron preparations.

Postabsorptive serum iron level was determined after oral administration of the compounds to human. In serum and whole blood, Fe3+ was measured by ion chromatography (IC) using a pyridine-2,6-dicarboxylic acid (PDCA) as an eluent. The serum sample solutions were pretreated with I N HCI and 50% TCA. The whole blood sample solutions were treated with 3 N HCI for 30 min at 125 degrees C. The limit of detection (LOD) of the IC technique is 0.2 microM for Fe2- and 0.1 microM for Fe3+. The area under concentration (AUC) can be obtained by the above analytical condition. In addition, to compare the stability of Fe2+ to that of Fe3+ in pharmaceutical preparations, accelerated stability test was carried out. After storing the samples under 40 degrees C, 75%RH in light-resistant container for various time intervals, the contents of iron of different valencies were determined separately by the IC technique and the change and/or the interchange of among those iron species in preparations was investigated. Iron raw materials are stable, but Fe2+ in Fe3+ source materials was slightly converted to Fe3+ by oxidation. Fe2+ in Fe3+ source raw materials and Fe3+ in Fe2+ raw materials are determined as impurities. Therefore, IC technique is found to be an appropriate method for comparative evaluation of dissimilar bioavailability of Fe2+ and Fe3+, stability of Fe2+ and Fe3+ raw materials and preparations.

Biological Availability↗
PubMed1998

Inhibitory effects of oxyradicals on surfactant function: utilizing in vitro Fenton reaction.

The inhibitory effects of reactive oxygen species (ROS) on the surface tension-lowering abilities of three surfactants were compared: natural lung surfactant (NLS), KL4 surfactant containing synthetic peptide resembling the hydrophobic/hydrophilic domains of SP-B in an aqueous dispersion of phospholipids, and Survanta (SUR) containing SP-B and SP-C. The inhibitory concentrations of Fenton reactants (i.e. 0.65 mM FeCl2, 0.65 mM EDTA, 30 mM H2O2), deduced from dose-response plots of FeCl2 on minimum surface tension (MST) of SUR, were used to assess the Fenton effect on biophysical properties of various surfactants. Neither H2O2 (30 mM) nor FeCl2 with EDTA (both 0.65 mM) alone affected surfactant function, but when mixed together significantly increased (p < 0.01) the MST of SUR compared with KL4 (p < 0.05) in a FeCl2 concentration-dependent manner. This effect on NLS was not significant (p = 0.05) at similar phospholipid concentrations. Also, the range of increases in surface adsorption in mN/m at equilibrium surface tension (EST) was 27-40 for SUR, 36-44 for KL4, and 24-25 for NLS. We speculate that the presence of SP-A and the catalase content in NLS may have protective effects on inactivation of NLS by ROS. We conclude that the in vitro Fenton effect could be a valuable test system for comparing the inactivation range of surfactants by oxyradicals.

Animals↗
PubMed2001

Simultaneous determination of Fe(II) and Fe(III) in waters by capillary isotachophoresis.

An ITP method for the simultaneous determination of Fe(II) and Fe(III) in waters, based on separation of their EDTA and fluoride complexes, respectively, was developed. The leading electrolyte used consists of chlorides, La(III) as co-counter ion and is buffered with beta-alanine to pH = 3.5. The terminating electrolyte contains caproic acid and L-histidine (pH = 4.5). The method was validated and tested with samples of artificial, ground and treated water with good results, comparable to those obtained by other analytical techniques. Fe(II) and Fe(III) up to 20 mg/L were measured with an RSD = 1.4-1.5% and detection and determination limits of 0.8-0.9 and 3.0-3.5 mg/L, respectively. The ITP method can be recommended for routine utilization in hydroanalytical laboratories.

Chemistry Techniques, Analytical↗
PubMed2001

Flow-injection manifold for the simultaneous spectrophotometric determination of Fe(II) and Fe(III) using 2,2'-dipyridyl-2-pyridylhydrazone and a single-line double injection approach.

A simple and rapid flow-injection (FI) method is reported for the simultaneous spectrophotometric determination of Fe(II) and Fe(III) in pharmaceutical products. The method is based on the reaction of Fe(II) with 2,2'-dipyridyl-2-pyridylhydrazone (DPPH) in acidic medium to form a water-soluble reddish complex (lambdamax=535 nm). Fe(III) reacts with DPPH under flow conditions only after its on-line reduction by ascorbic acid (AsA). Both analytes were determined in the same run via a double-injection valve, which enabled the simultaneous injection of two sample volumes in the same carrier stream (,,single-line double-injection" approach). The two well-defined peaks produced corresponded to total iron [Fe(II)+Fe(III)] and Fe(II). Speciation of the analytes in their mixtures was achieved by multiple regression analysis. The calibration curves obtained were linear over the ranges 0-30 and 0-50 mg L(-1) for Fe(II) and Fe(II), respectively, and the precision [s(r)=1.0% for Fe(II) and 1.5% for Fe(III)] was satisfactory. The method proved to be selective and adequately sensitive (cL=0.25 and 0.17 mg L(-1) for Fe(III) and Fe(II), respectively, in mixtures). Application of the method to the analysis of pharmaceutical samples resulted in excellent accuracy; the percent mean recoveries were in the range 99.0-102.0% for both Fe(II) and Fe(III) and the mean relative error was e(r)=1.0%.

2,2'-Dipyridyl↗
PubMed2006

Structure of microbial communities performing the simultaneous reduction of Fe(II)EDTA.NO2- and Fe(III)EDTA -.

BioDeNOx is a combined physicochemical and biological process for the removal of nitrogen oxides (NOx) from flue gas. In the present study, two anaerobic bioreactors performing BioDeNOx were run consecutively (RUN-1 and RUN-2) at a dilution rate of 0.01 h(-1) with Fe(II)EDTA.NO(2-) and Fe(III)EDTA(-) as electron acceptors and ethanol as electron donor. The measured protein concentration of the reactor biomass of both runs was 120 mg/l. Different molecular methods were used to determine the identity and abundance of the bacterial populations in both bioreactors. Bacillus azotoformans strain KT-1 was recognized as a key player in Fe(II)EDTA.NO(2-) reduction. PCR-denaturing gradient gel electrophoresis analysis of the reactor biomass showed a greater diversity in RUN-2 than in RUN-1. Enrichments of Fe(II)EDTA.NO(2-) and Fe(III)EDTA(-) reducers and activity assays were conducted using the biomass from RUN-2 as an inoculum. The results on substrate turnover, overall microbial diversity, and enrichments and finally activity assays confirmed that ethanol was used as electron donor for Fe(II)EDTA.NO(2-) reduction. In addition, the Fe(III)EDTA(-) reduction rate of the microbial community proved to be feasible enough to run the bioreactors, ruling out the chemical reduction of Fe(III)EDTA(-) with sulfide as was proposed by other researchers.

Anaerobiosis↗
PubMed2000

Sequestration of iron by Lewy bodies in Parkinson's disease.

Central to the oxidative stress hypothesis of Parkinson's disease (PD) pathogenesis is the ability of iron to generate hydroxyl radicals via the Fenton reaction, and the consistent demonstration of iron elevation in the pars compacta region of the substantia nigra. However, uncertainty exists as to whether the excess iron exists in a state suitable for redox chemistry. Here, using a method we developed that detects redox-active iron in situ, we were able to demonstrate strong labeling of Lewy bodies in substantia nigra pars compacta neurons in PD. In contrast, cortical Lewy bodies in cases of Lewy body variant of Alzheimer's disease were unstained. While the presence of elevated iron in PD substantiates the oxidative stress hypothesis, one must remember that these are viable neurons, indicating that Lewy bodies may act to sequester iron in PD brains in a protective, rather than degenerative, mechanism. The absence of redox-active iron in neocortical Lewy bodies highlights a fundamental difference between cortical and brain stem Lewy bodies.

Aged↗
PubMed1999

Oral iron is sufficient for erythropoietin treatment of very low birth-weight infants.

UNLABELLED: The aim of this study was to compare two different doses and means of administration of iron in recombinant human erythropoietin (rHuEPO)-treated very low birth-weight (VLBW) infants. VLBW infants (n = 41) were randomized to one of three groups. Fourteen infants were treated with rHuEPO (300 IU/kg three times a week s.c.) and oral iron (ferrofumarate, 6 mg of iron/kg per day). Another 14 infants received the same erythropoietin dose and intramuscular iron (ferroxypolymaltose, once 12 mg of iron/kg weekly). Thirteen infants were treated with the same dose of intramuscular iron but did not receive rHuEPO. After the 3-week study period, haemoglobin concentrations and reticulocyte counts were similar in the rHuEPO-treated groups and both were higher than in the group not receiving rHuEPO (P < 0.001). In both rHuEPO-treated groups the transferrin receptor concentration increased from 6.8-7.2 mg/l to 10.5-11.3 mg/l. CONCLUSION: In erythropoietin-treated very low birth weight infants the iron need for erythropoiesis can be met by oral administration of iron.

Administration, Oral↗
PubMed1999

Iron enhancement of experimental infection of mice by Tritrichomonas foetus.

The ability of a microbial invader to acquire iron from its vertebrate host has been recognized as an important virulence mechanism in some pathogenic bacteria. We examined the involvement of similar mechanisms in an experimental infection of mice by a protozoan pathogen of cattle, Tritrichomonas foetus. In a series of experiments, outbred ICR mice were inoculated intraperitoneally with two strains of T. foetus, the moderately virulent KV-1 (approximately 5% mortality rate) and the highly virulent LUB-1MIP (approximately 80% mortality rate). Treatment of mice with ferric ammonium citrate (FeAC) (100 mg/kg per day intraperitoneally) increased the mortality rate caused by the KV-1 infection up to the level determined for the highly virulent strain. The treatment effect was dose dependent and required early administration of FeAC after inoculation of parasites and its continued supply for at least 3 subsequent days. Daily sampling of peritoneal exudate showed that the infection-enhancing effect of iron overload was associated with a stimulation of parasite multiplication, which in the case of KV-1 infection was strongly suppressed in untreated mice. Consistent with these findings, the strain of lower virulence (KV-1) showed considerably lower efficiency accumulating radiolabeled iron from transferrin and a low-molecular source [Fe(III)nitrilotriacetic acid] in vitro. The results indicate an involvement of iron uptake mechanisms by the parasite as a virulence factor in T. foetus infection.

Animals↗
PubMed2005

Self-hydroxylation of taurine/alpha-ketoglutarate dioxygenase: evidence for more than one oxygen activation mechanism.

2-Aminoethanesulfonic acid (taurine)/alpha-ketoglutarate (alphaKG) dioxygenase (TauD) is a mononuclear non-heme iron enzyme that catalyzes the hydroxylation of taurine to generate sulfite and aminoacetaldehyde in the presence of O2, alphaKG, and Fe(II). Fe(II)TauD complexed with alphaKG or succinate, the decarboxylated product of alphaKG, reacts with O2 in the absence of prime substrate to generate 550- and 720-nm chromophores, respectively, that are interconvertible by the addition or removal of bound bicarbonate and have resonance Raman features characteristic of an Fe(III)-catecholate complex. Mutagenesis studies suggest that both reactions result in the self-hydroxylation of the active-site residue Tyr73, and liquid chromatography nano-spray mass spectrometry/mass spectrometry evidence corroborates this result for the succinate reaction. Furthermore, isotope-labeling resonance Raman studies demonstrate that the oxygen atom incorporated into the tyrosyl residue derives from H2 18O and 18O2 for the alphaKG and succinate reactions, respectively, suggesting distinct mechanistic pathways. Whereas the alphaKG-dependent hydroxylation likely proceeds via an Fe(IV) = O intermediate that is known to be generated during substrate hydroxylation, we propose Fe(III)-OOH (or Fe(V) = O) as the oxygenating species in the succinate-dependent reaction. These results demonstrate the two oxygenating mechanisms available to enzymes with a 2-His-1-carboxylate triad, depending on whether the electron source donates one or two electrons.

Bicarbonates↗
PubMed2005

Cooperativity and intermediates in the equilibrium reactions of Fe(II,III) with ethanethiolate in N-methylformamide solution.

The reaction of FeCl(2) or FeCl(3) with sodium ethanethiolate (SEt) in N-methylformamide (NMF) has been reevaluated to rectify a previous Fe(II) oxidation artifact. On titrating Fe(II) with EtS(-) concentrations up to 12 mol Eq, new features in the UV/vis spectrum (epsilon(344)=(3.1+/-0.2)x10(3) M(-1) cm(-1); epsilon(486)=(4.5+/-0.1)x10(2) M(-1) cm(-1)) indicated that the first observable step was the formation of a single complex different from the known tetrahedral tetrathiolate, [Fe(SEt)(4)](2-) . As the EtS(-) concentration increased past 12.5 mol Eq the UV/vis spectrum gradually transformed to that of [Fe(SEt)(4)](2-) (lambda(max)=314 nm). A Hill-formalism fit to the titration data of the initially formed complex indicated cooperative ligation by three ethanethiolate ions, with K(coop)=(1.7+/-0.1)x10(3) M(-3) and Hill "n"=2.4+/-0.1 (r=0.997). The 3:1 EtS(-)-Fe(II) complex is proposed to be [Fe(2)(SEt)(6)](2-). Titration of Fe(III) with EtS(-) showed direct cooperative formation of [Fe(SEt)(4)](-) [epsilon(340)=(3.4+/-0.5)x10(3) M(-1) cm(-1)] with a Hill-formalism K(coop)=(4.3+/-0.1)x10(2) M(-4) and a Hill coefficient "n"=3.7+/-0.2 (r=0.996). Further ligation past [Fe(SEt)(4)](-) was observed at EtS(-) concentrations above 35 mol Eq. The Fe(III) Hill constants are at variance with our previous report. However, the UV/vis spectrum of Fe(III) in NMF solution was found to change systematically over time, consistent with a slow progressive deprotonation of [Fe(nmf)](3+). The observed time-to-time differences in the equilibrium chemistry of Fe(III) with ethanethiolate in NMF thus reflect variation in the microscopic solution composition of FeCl(3) in alkaline NMF solvent. These results are related to the chemistry of nitrogenase FeMo cofactor in alkaline NMF solution.

Azotobacter vinelandii↗