Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Iron Compounds”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 811 records · Page 45Linked to original sources
PubMed1990

Chelators affecting iron absorption in mice.

The effect of natural and synthetic chelators on iron (59Fe) absorption in mice has been studied in three different experiments using single or repeated intragastric administrations of chelator iron (59Fe) complexes of different chelator doses. The amount of 59Fe in whole animals, their excretions and also distribution of 59Fe in blood, liver, spleen and heart was measured at one, three and eight weeks following the 59Fe-chelator administrations and compared to controls which received the same amount of iron (59Fe) but no chelator. 2-Hydroxy-4-methoxypyridine-1-oxide and maltol, which form lipophilic iron complexes, were found to cause an increase of 59Fe absorption while other chelators caused a decrease either by precipitating iron eg. 2-hydroxypyridine-1-oxide or by forming non absorbable soluble iron complexes eg. desferrioxamine, mimosine, EDTA. 1,2-Dimethyl-3-hydroxypyrid-4-one caused a decrease in iron absorption at a high dose (10 mg) by comparison to the control group but it did not significantly alter iron absorption at a lower dose (2 mg). It is suggested that natural and synthetic iron chelating compounds influence the absorption of iron and some may have a use in the treatment of diseases associated with gastro-intestinal iron absorption imbalance.

Animals↗
PubMed1990

Novel effect of aromatic compounds on the iron-dependent expression of the Escherichia coli K12 manganese superoxide dismutase (sodA) gene.

In Escherichia coli, the superoxide dismutase genes (sodA and sodB) sense the availability of Fe through the action of the fur locus [E. C. Niederhoffer, C. M. Naranjo, K. L. Bradley, J. A. Fee (1990) Control of Escherichia coli superoxide dismutases (sodA and sodB) genes by the ferric uptake regulation (fur) locus, J. Bacteriol. 172, 1930-1938]. Previous work from other laboratories has shown that a variety of metal chelators and of redox-active aromatic compounds can dramatically induce expression of sodA. Here we show that non-redox-active, non-metal-chelating aromatic compounds also enhance expression of a chromosomal sodA gene fusion and that these effects are strongly modulated by the Fur phenotype (Fur +/-) and by the availability of iron in the culture medium. The compounds studied were ethidium bromide, hemin, 2,2'-bipyridine, 1,10-phenantroline, 4,7-phenantroline, rhodamine B1, rhodamine 6G, and, for comparison to previous studies, Paraquat.

Ethidium↗
PubMed1997

Synthesis, Structure, Magnetic Behavior, and Mössbauer Spectroscopy of Two New Iron(II) Spin-Transition Compounds with the Ligand 4-Isopropyl-1,2,4-triazole. X-ray Structure of [Fe(3)(4-isopropyl-1,2,4-triazole)(6)(H(2)O)(6)](tosylate)(6).2H(2)O.

Two new iron(II) compounds with the formula [Fe(3)(iptrz)(6)(H(2)O)(6)]X(6).xH(2)O (with iptrz = 4-isopropyl-1,2,4-triazole and X = p-toluenesulfonate (Tos) or trifluoromethanesulfonate (Trifl)) were synthesized. The crystal structure of [Fe(3)(iptrz)(6)(H(2)O)(6)](Tos)(6).2H(2)O (I) has been solved at room temperature. Crystals of I are triclinic, space group P&onemacr; with a = 12.8820(11) Å, b = 15.580(2) Å, c = 24.445(4) Å, alpha = 79.270(12) degrees, beta = 86.688(11) degrees, gamma = 83.007(8) degrees, Z = 2. The structure of I consists of linear trinuclear cations with a +6 charge and noncoordinated anions and lattice water molecules. The central iron ion is located on an inversion center and is coordinated by 6 nitrogen atoms of 6 iptrz molecules bridging via the nitrogen atoms in the 1,2-positions. Each external iron atom completes its coordination sphere with three coordinated water molecules. The temperature dependent magnetic measurements of compound I and [Fe(3)(iptrz)(6)(H(2)O)(6)](Trifl)(6) (II) show that both compounds exhibit a gradual spin conversion of the central iron ion centered at T(1/2) = 242 K for I and 187 K for II. Temperature dependent Mössbauer spectroscopy measurements on I show the behavior expected for a compound of this nature. The measurements on II indicate a strong influence of the spin conversion of the central iron ion on both external iron ions. The nature of this phenomenon is proposed to be connected to a very rigid lattice structure (ionic, H-bonding) connecting the trinuclear units.

Journal Article↗
PubMed1975

Effect of vanadium on growth, chlorophyll formation and iron metabolism in unicellular green algae.

In the presence of vanadium, growth of Scenedesmus obliquus and Chlorella pyrenoidosa was increased five to sixfold as determined by dry weight, when cultured under autotrophic conditions for 7 days. The stimulation by vanadium decreased with increasing stability towards hydrolysis of the iron(III)-compounds added. Pentavalent vanadium (20 mug V/1 as NH4VO3) was able to overcome completely a limited iron-deficiency in the algae following growth in presence of 1.8 - 10(-5) m ferric chloride. Vanadium did not alter the iron uptake into the algal cells. 90% of offered 48V was taken up by Scenedesmus obliquus during 5 days of growth, and 21% thereof were found in the chloroplast fraction. In presence of vanadium, the chlorophyll formation was stimulated in Scenedesmus obliquus. This stimulation by vanadium was found to be light-dependent but occurred to a certain extent in the dark also. The main porphyrin of the yellow mutant 211-11h/20 of Chlorella vulgaris was identified as protoporphyrin-IX. The formation of this compound was stimulated by vanadium within 10 days up to 83%. The role of vanadium in the biosynthesis of chlorophylls is discussed.

Chlorella↗
PubMed1990

Effect of EDTA on the bioavailability to rats of fortification iron used in Egyptian balady bread.

The effectiveness of EDTA compounds on iron fortificants for potential use in Egyptian balady bread was tested in sixty Sprague-Dawley weanling male rats by the haemoglobin regeneration efficiency (HRE) method. To confirm HRE-derived findings, eight groups of ten animals were repleted with a modified American Institute of Nutrition (1977; AIN) 76A diet, fortified with ferric phosphate, electrolytic Fe, carbonyl Fe or ferrous sulphate, with and without ascorbic acid. Results without ascorbic acid were comparable to findings of a human study by Forbes et al. (1989). Bioavailability of EDTA-enhanced fortificants, FeSO4 + Na2EDTA and NaFe(III)EDTA, was compared with that of FeSO4 in six groups of ten animals repleted with a ground Egyptian bread meal or a casein-based AIN diet fortified with one of the three compounds. Addition of either EDTA compound significantly increased bioavailability of Fe in Egyptian balady bread. When present in the less inhibitory casein meal, however, FeSO4 + Na2EDTA fortification was significantly less effective than NaFe(III)EDTA or the reference FeSO4. Results indicate that NaFe(III)EDTA may be the fortificant of choice in a mixed diet. Further study of EDTA-enhanced Fe fortificants is needed.

Anemia, Hypochromic↗
PubMed1993

Ascorbate-dependent formation of hydroxyl radicals in the presence of iron chelates.

The autoxidation of L-ascorbate on incubation in saline phosphate buffer (pH 7.4) is accompanied by hydroxyl radical (.OH) generation. The metal chelator EDTA showed significant inhibition of ascorbate autoxidation and ascorbate-dependent .OH release. On the other hand, Fe2+ (EDTA) greatly augmented both ascorbate autoxidation and ascorbate-dependent .OH production. The biological iron chelating compounds such as ATP, ADP, citrate and pyrophosphate suppressed both ascorbate autoxidation and ascorbate-mediated .OH production, thereby indicating that these compounds suppress the activating effect of iron. Ascorbate autoxidation and ascorbate-dependent .OH formation, stimulated by Fe2+ (EDTA) were significantly inhibited by .OH scavengers, namely mannitol, thiourea and sodium formate, as well as by catalase and to a lesser extent by bovine serum albumin, superoxide dismutase (native and heat denatured) and heat denatured catalase.

Adenosine Diphosphate↗
PubMedDate not supplied

Structure of a new tetranuclear iron(III) complex with an oxo-bridge; factors to govern formation and stability of oxo-bridged iron(III) species in the L-subunit of ferritin.

We have investigated the reaction products of several iron(III) compounds with hydrogen peroxide, and have found that hydrogen peroxide promotes the formation of an oxo-bridged iron(III) species in the presence of methanol (electron donor), and carboxyl groups of the ligand systems play a role to give the tetranuclear iron(III) compound containing a bent Fe-O-Fe unit (O: oxo oxygen atom). Based on the present results and the facts that L-chains of human ferritins lack ferroxidase activity, but are richer in carboxyl groups (glutamates) exposed on the cavity surface, it seems reasonable to conclude that (i) the hydrogen peroxide released in the H-subunit may contribute to the formation of a diferric oxo-hydrate in the L-subunit, (ii) the formation of a bent oxo-bridged iron(III) species is essentially important in the L-subunit, and (iii) rich carboxyl groups in L-subunits contribute to facilitate iron nucleation and mineralization through the capture and activation of the peroxide ion, and formation of a stable bent oxo-bridged iron(III) species.

Ceruloplasmin↗
PubMed2007

Metal-chelating compounds produced by ectomycorrhizal fungi collected from pine plantations.

AIMS: To investigate the in vitro production of metal-chelating compounds by ectomycorrhizal fungi collected from pine plantations in southern Chile. METHODS AND RESULTS: Scleroderma verrucosum, Suillus luteus and two isolates of Rhizopogon luteolus were grown in solid and liquid modified Melin-Norkans (MMN) media with and without iron addition and the production of iron-chelating compounds was determined by Chrome Azurol S (CAS) assay. The presence of hydroxamate and catecholate-type compounds and organic acids was also investigated in liquid medium. All isolates produced iron-chelating compounds as detected by CAS assay, and catecholates, hydroxamates as well as oxalic, citric and succinic acids were also detected in all fungal cultures. Scleroderma verrucosum produced the greatest amounts of catecholates and hydroxamates whereas the highest amounts of organic acids were detected in S. luteus. Nevertheless, the highest catecholate, hydroxamate and organic acid concentrations did not correlate with the highest CAS reaction which was observed in R. luteolus (Yum isolate). CONCLUSIONS: Ectomycorrhizal fungi produced a variety of metal-chelating compounds when grown in liquid MMN medium. However, the addition of iron to all fungi cultures reduced the CAS reaction, hydroxamate and organic acid concentrations. Catecholate production was affected differently by iron, depending on the fungal isolate. SIGNIFICANCE AND IMPACT OF THE STUDY: The ectomycorrhizal fungi described in this study have never been reported to produce metal-chelating compound production. Moreover, apart from some wood-rotting fungi, this is the first evidence of the presence of catecholates in R. luteolus, S. luteus and S. verrucosum cultures.

Basidiomycota↗
PubMed1984

Vibriobactin, a siderophore from Vibrio cholerae.

A novel siderophore (microbial iron transport compound) has been isolated from low iron cultures of Vibrio cholerae. Belonging to the catecholamide family of chelators, it has been shown to contain three residues of 2,3-dihydroxybenzoic acid and two residues of threonine. Both threonine moieties are present in the form of oxazoline rings. Furthermore, the polyamine backbone of the molecule was proved to be not spermidine, but the rare N-(3-aminopropyl)-1,3-diaminopropane, norspermidine. The structure of the new siderophore has been determined to be N-[3-(2,3-dihydroxybenzamido)propyl]-1, 3-bis[2,3-dihydroxyphenyl)-trans-5-methyl-2-oxazoline-4-carboxamido]prop ane. The compound has been given the trivial name vibriobactin. Mutants defective in the synthesis and utilization of vibriobactin were isolated. In an iron-limited environment V. cholerae was found to respond more strongly to vibriobactin, agrobactin, and ferrichrome than to enterobactin.

Catechols↗
PubMed1981

Iron transfer form transferrin to ferritin mediated by polyphosphate compounds.

We have studied iron transfer from transferrin to ferritin in the presence of ATP, GTP, ADP, AMP and 2,3-diphosphoglycerate. These compounds, with the exception of AMP, can release iron from transferrin at pH 7.4 and form a stable Fe(III)-phosphate complex. From these complexes, only a limited number of Fe(III) atoms can be incorporated into ferritin. Ascorbate enhances iron transfer from transferrin to ferritin at the beginning of the process but subsequently inhibits further iron deposition in ferritin.

Adenine Nucleotides↗
PubMed2006

Caged-iron chelators a novel approach towards protecting skin cells against UVA-induced necrotic cell death.

Exposure of human skin cells to solar UVA radiation leads to an immediate dose-dependent increase of labile iron that subsequently promotes oxidative damage and necrotic cell death. Strong iron chelators have been shown to suppress cell damage and necrotic cell death by moderating the amount of labile iron pool (LIP), but chronic use would cause severe side effects owing to systemic iron depletion. Prodrugs that become activated in skin cells at physiologically relevant doses of UVA, such as "caged-iron chelators", may provide dose- and context-dependent release. Herein, we describe prototypical iron chelator compounds derived from salicylaldehyde isonicotinoyl hydrazone and pyridoxal isonicotinoyl hydrazone and demonstrate that the intracellular LIP and subsequent necrotic cell death of human skin fibroblasts is significantly decreased upon exposure to a combination of the prototypical compounds and physiologically relevant UVA doses. Iron regulatory protein bandshift and calcein fluorescence assays reveal decreased intracellular LIP following irradiation of caged-chelator-treated cells, but not in control samples where either UVA light, or caged-chelator is absent. Furthermore, flow cytometry shows that these compounds have no significant toxicity in the skin fibroblasts. This novel light-activated prodrug strategy may therefore be used to protect skin cells against the deleterious effects of sunlight.

Cells, Cultured↗
PubMedDate not supplied

The significance of iron in infection.

The iron-binding proteins transferrin and lactoferrin restrict the amount of ionic iron available in body fluids to 10(-18) M. This amount is insufficient for normal bacterial growth, and pathogens acquire iron either by producing iron-chelating agents or by utilizing heme compounds. Iron-binding proteins, in combination with antibodies, often have powerful bacteriostatic effects in vitro and are essential for protection against many infections. Lactoferrin appears to be essential for the bactericidal function of polymorphonuclear leukocytes against Pseudomonas aeruginosa. Fever lowers the concentration of iron in serum and favors resistance to infection. Liberation of heme compounds can enhance clinical infections.

Adaptation, Physiological↗
PubMed1980

Iron acquisition by Neisseria meningitidis in vitro.

Assays employing iron-limited solid and liquid, defined and complex media were devised to test the iron requirements of Neisseria meningitidis. A variety of tests yielded no evidence for the secretion of a soluble iron-binding substance (siderophore) by the meningococci. The meningococci were unable to use iron bound to some common hydroxamate- and catechol-type siderophores or even compete with them for iron in the growth medium. A total of 20 strains of meningococci, differing widely in their virulence for mice, were similar in ability to acquire iron from a variety of iron-containing substances; the iron in such compounds as hog gastric mucin, citrate, hemoglobin, and myoglobin was easily acquired, whereas the iron in compounds such as ferrioxamine B, ferrichrome,ferritin, Imferon, cytochrome c, FePO4, and [Fe(OH)3]n was not readily available. No correlation was noted between the ability of particular strains to obtain iron from compounds and virulence in mice. Iron complexed or chelated with a number of metabolic organic acids, polyphosphates, and several synthetic polycarboxylic acids was readily available to all strains, even though some of the compounds used had high effective binding constants for iron and all were in 3- or 10-fold molar excess over the iron present. The addition of some of these iron-complexing substances (e.g., citrate and pyrophosphate) in iron-free form made many biologically important iron compounds that are normally inaccessible to the meningococci readily available.

Animals↗
PubMed1985

Efficacy of sulfhydryl compounds as inhibitors of iron-dependent doxorubicin-enhanced lipid peroxidation.

The ability of sulfhydryl compounds to inhibit doxorubicin enhanced lipid peroxidation in the presence of added iron was evaluated. Optimal conditions for doxorubicin-enhanced lipid peroxidation were 25 microM doxorubicin, 2 mM ADP and 250 microM ferric chloride at pH 8.0. Lipid peroxidation was inhibited by EDTA (500 microM), SKF 525 A (100 microM) and vitamin E (0.1 unit/ml). Cysteamine (1 mM) stimulated basal lipid peroxidation but produced net inhibition of lipid peroxidation with doxorubicin. Cysteamine (10 mM) was more efficacious at inhibiting lipid peroxidation. N-acetylcysteine at 1 and 10 mM was a potent stimulator of lipid peroxidation and was ineffective at inhibiting lipid peroxidation in the presence of doxorubicin either at optimal or suboptimal concentrations of iron. In contrast, glutathione (1 mM) was a potent inhibitor of lipid peroxidation. The data suggests that N-acetylcysteine protects against doxorubicin by prior conversion to glutathione.

Acetylcysteine↗