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At least 145 records · Page 8Linked to original sources
PubMed1988

[Ferrocene, ruthenocene and rhodocene analogs in haloperidol synthesis and organ distribution after labeling with 103Ru and 103mRh].

Ferrocene-Haloperidol was synthesized by N-alkylation of 4-(4'-chlorophenyl)- 4-hydroxypiperidine with 1-ferrocenyl-4-chlor-butan-1-on. By heating the ferrocene-haloperidol with 103RuCl3 the 103Ru-labelled ruthenocene-haloperidol was obtained. This compound showed a high affinity for lung but not for brain in rats and mice. The decay of the 103Ru labelled compound results in the formation of the 103mRh labelled rhodocene-haloperidol, which is rapidly oxidized by air to the corresponding rhodocinium-haloperidol. This compound can be separated by extraction and TLC.

Animals↗
PubMed1988

[Improved diagnosis using deuterated radiopharmaceuticals?--A comparison of the brain affinity of amphetamine analogs].

Ruthenocene amphetamine analogues have the same brain uptake as iodo-labelled amphetamines. This paper compares the organ-distribution of 103Ru labelled ruthenocene- or ferrocene-amphetamine analogues in mice and rats with the same amphetamine in which H-atoms were partly substituted by D-atoms. The uptake in the brain is increased up to 180-200% for deuterium substituted compounds. The pattern of excreted metabolites leads to the conclusion that the deuterated amphetamines are more slowly metabolised than normal (H) compounds.

Amphetamine↗
PubMed1991

An approach to the use of stable isotopes for DNA sequencing.

The sequencing of DNA by current procedures involves the use of radioisotopic or fluorescent labels. We propose that stable isotopes can be used as such labels and that the large number of stable isotopes available would allow multiplexing so that many DNA segments could be sequenced simultaneously. We have developed methods to use 57Fe2O3 to synthesize ferrocene and to attach the ferrocene to the 5' end of oligonucleotides. The 57Fe-labeled M13 universal primer functioned normally in a Sanger sequencing procedure. When a 57Fe-labeled oligonucleotide had migrated on a polyacrylamide gel it was readily located on the dried gel by scanning with resonance ionization spectroscopy (RIS) coupled with mass spectrometry. Using a 57Fe-labeled primer in a PCR reaction a 2000-bp DNA was produced that was detected by RIS on nylon membrane after agarose electrophoresis. The rapid analysis features of RIS coupled with the multispectral multiplexing possibilities of stable isotopes should significantly increase the rate of determination of DNA sequences.

Base Sequence↗
PubMed1993

Local monitoring of proton spin diffusion in static and rotating samples via spy detection.

A method is described for investigating local proton "spin diffusion" by means of a 13C spin probe. The procedure does not require spectral resolution of proton resonance lines and can be applied in the laboratory frame of reference as well as in the rotating frame. Experimental results are presented for a static single crystal of ferrocene and for a powder sample under magic-angle spinning. The spin-diffusion rate constant is found to be proportional to the spinning speed in the range from 1 to 8 kHz.

Carbon↗
PubMed1994

Cross-polarization dynamics and spin diffusion in some aromatic compounds.

The inversion-recovery cross-polarization (IRCP) magic-angle spinning experiment has been applied to study the 13C-1H cross-polarization dynamics of protonated aromatic carbons in ferrocene, 5,6-dimethoxyindole (DMI) and some indole derivatives. Using the 13C-detected proton spin diffusion (SD) experiment recently developed by Zhang et al. [Solid State Nucl. Magn. Reson., 1 (1992) 313], the slow decaying or incoherent stage of the IRCP experiment is shown to be controlled by the spin diffusion process at the directly bound proton. Moreover, a simple phenomenological model treating spin diffusion as a relaxation process provides an excellent agreement with both the IRCP and SD experimental data for all the different C-H pairs of DMI and its derivatives. The resulting time constants of the non-exponential spin diffusion decays are related to the local intra- and intermolecular network of dipolar interactions. This model is nevertheless found to be inadequate for ferrocene because intramolecular spin diffusion then has an inhomogeneous character.

Diffusion↗
PubMed1992

Mediated amperometric determination of xylose and glucose with an immobilized aldose dehydrogenase electrode.

An enzyme electrode was constructed for amperometric determination of xylose and glucose. The electrode is based on the PQQ-dependent membrane-bound aldose dehydrogenase (ALDH) from Gluconobacter oxydans. ALDH was covalently immobilized on a graphite electrode. Immobilized dimethylferrocene, soluble ferrocene carboxylic acid and phenazine methosulphate were used as electron transfer mediators. When xylose was measured electrochemically using an electrode modified with ALDH and dimethylferrocene, the linear measurement range extended to 100 mM. For glucose measurement the linear measurement range was about one-tenth of that for xylose. The electrode showed fairly good stability; 50% of the original electrode response was still obtained after 5 days of intermittent use. The effect of possible leakage of adsorbed mediator was determined by measuring the response of an electrode with soluble mediator as a function of time. The reproducibility of the electrode was good, the standard deviation of the electrode response in ten measurements with the same electrode being only 2.7%.

Biosensing Techniques↗
PubMed1992

Amperometric enzyme electrode for determination of theophylline in serum.

This paper describes an amperometric enzyme electrode for the rapid determination of theophylline in serum. The method is based on the catalysed oxidation of theophylline by the haem-containing enzyme theophylline oxidase. Results are presented for two approaches. First, ferrocene monocarboxylic acid was used as a mediator. The second-order rate constant was 1.1 x 10(3) 1 mol-1 s-1. Secondly, the organic conducting salt NMP.TCNQ was used to construct enzyme electrodes. These electrodes were employed for the rapid (60 s) measurement of theophylline in serum at a working potential of +100 mV versus Ag/AgCl. Linear calibration curves were obtained over the clinically relevant range (y = 0.13x + 0.22, n = 8). Caffeine, theobromine and 3-methylxanthine at levels up to 100 mg l-1 do not interfere and 1-methylxanthine shows cross-reactivity at concentrations greater than 50 mg l-1.

Biosensing Techniques↗
PubMed1993

Non-leaking amperometric biosensors based on high-molecular ferrocene derivatives.

Poly(ethylene glycol)-bound ferrocene derivatives, synthesized after activation of ferrocene carboxylic acid with 1,1'-bis carbonyl diimidazol, are able to transfer electrons from the active site of reduced glucose oxidase to electrode surfaces. This opens a route to non-leaking mediated enzyme electrodes for the determination of glucose.

Biosensing Techniques↗
PubMed1995

A glucose sensor fabricated by the screen printing technique.

A novel glucose sensor employing ferrocene-modified glucose oxidase is fabricated using the screen printing technique. Glucose oxidase is covalently bound to the electron mediator ferrocenecarboxylic acid in order to obtain higher enzyme activity. The ferrocene-glucose oxidase shows an increased catalytic current because the ferrocene acts as an electron transfer relay between the active centre of the enzyme and the gold electrode. Glucose sensors employing enzymes modified with ferrocene in various ways are successfully fabricated using the screen printing technique. The ink component containing the ferrocene-glucose oxidase is specially developed to be applicable to the printing machine. The printed glucose sensor chip offers a stable calibration profile and stable electrochemical properties.

Biosensing Techniques↗
PubMed2025

Electrochemical sensor toolkit for simultaneous glutamate detection at edge of cleft and peri-soma.

Simultaneously monitoring glutamate (Glu) dynamic at edge of synaptic cleft and peri-soma is crucial for understanding Glu-related pathology. Here, we created an electrochemical Glu sensors toolkit with spatial resolution of ∼60 nm, combining biologically engineered Glu binding protein for specifically capturing Glu together with chemically designed ferrocene groups for signal labeling. Modulation conjugation approach between GluR and ferrocene significantly improved sensitivity up to 32-folds. More importantly, protein engineering of residue mutation and linker peptides flexibility expanded linear range from 10 μM to 6 mM, accelerated on/off times down to 35/40 ms. This toolkit realized real-time quantifying of Glu both at edge of cleft and peri-soma, we discovered that Glu was almost released through SLC7A11 channels in calyx of held synapse upon oxygen-glucose-deprivation, while Glu was mainly released through hemichannels upon β-amyloid42 stimulation. Our work provided a methodology for investigating Glu release and reuptake and offered insights for Glu related pathology.

Glutamic Acid↗
PubMed1999

Effects of desferrithiocin and its derivatives on peripheral iron and striatal dopamine and 5-hydroxytryptamine metabolism in the ferrocene-loaded rat.

Iron overload disorders, such as beta-thalassaemia, are currently treated with the iron chelator desferrioxamine (DFO) or 1,2-dimethyl-3-hydroxypyridin-4-one (L1), which is currently under clinical evaluation. However, DFO is inactive orally and needs to be administered by intramuscular infusion, whilst there are concerns over the long-term effectiveness and toxicity of L1. In addition, both DFO and L1 affect brain dopamine (DA) and 5-hydroxytryptamine (5-HT) metabolism. In this study, the 3,5,5-trimethylhexanoyl ferrocene rat model of iron overload was used to compare the iron-chelating capabilities of a novel orally active siderophore, desferrithiocin (DFT) and its desmethyl derivatives DFT-D and DFT-L, to that of DFO, along with their ability to affect brain DA and 5-HT metabolism. Chronic administration of ferrocene produced a 12-fold increase in liver iron levels, as assessed by electrothermal atomic absorption. Subsequent treatment with DFT over a two-week period produced a 37% reduction in liver iron levels, whereas similar treatment with DFT-D and DFT-L produced a more marked reduction in these levels (65% and 59%, respectively) in the ferrocene-treated animals. In contrast, using the same dosing regimen, DFO and L1 only produced a 16% and 18% reduction, respectively, in liver iron levels. Both DFT and its derivatives failed to affect either striatal DA or 5-HT metabolism when assessed by HPLC. In view of the previously described oral bioavailability of DFT, the marked ability of DFT and its derivatives to chelate hepatic iron, and their inability to affect brain DA or 5-HT metabolism, such siderophores appear potentially useful clinical iron chelators.

Administration, Oral↗
PubMed1997

Site-specific introduction of an electroactive label into a non-electroactive enzyme (beta-lactamase I).

A cysteine residue was introduced close to the active site of beta-lactamase I by site-directed mutagenesis to replace tyrosine-105 and was subsequently modified with an electroactive SH-specific reagent, N-(2-ferrocene-ethyl)maleimide. The resulting modified enzyme became electroactive, showing good quasireversible electrochemistry which was characteristic of the attached ferrocene moiety while retaining its specific enzymatic activity. In the presence of a suicide substrate, 6beta-iodopenicillanic acid, the redox potential shifted +20 mV suggesting that the label was sensitive to changes in the active site of the enzyme.

Bacillus cereus↗
PubMed1992

Chemical modification of proteins under high pressure. Preparation of ferrocene-attached bovine serum albumin and glucose oxidase.

High hydraulic pressure was used for denaturing proteins during chemical modifications. Bovine serum albumin and glucose oxidase were selected as the first targets of this unique technique and the ferrocene group was introduced into them, to obtain a macromolecular electron mediator and a self-electron-mediating oxidase, respectively. The result was compared with those obtained under non-denaturing conditions and under urea-denatured conditions. As for the number of ferrocene group linked to the protein, the pressure denaturation is superior to chemical denaturants, where ferrocenecarboxyaldehyde was used as the modifier. In both proteins the ferrocene group seemed to be introduced mainly inside the molecules with the pressure method, as the native conformation of the protein was restored when the high pressure was removed.

Ferrous Compounds↗
PubMed1998

An improved method for the detection of changes in brain extracellular glutamate levels.

We developed a method for in vivo real-time monitoring of the concentration of extracellular glutamate ([Glu]e) in the brain under anoxic conditions. A dialysis electrode (Sycopel Int., UK) was employed as a sensing device to measure the concentration of glutamate by enzyme amperometry, and an electron mediator, ferrocene, was introduced into the electrode together with glutamate oxidase. The ferrocene was covalently conjugated with a high molecular weight molecule, bovine serum albumin, to avoid outward diffusion through the dialysis membrane. With this set-up, the amperometric response was independent of the pO2 around the electrode in vitro up to 400 microM glutamate. Using this method, we investigated the dynamics of [Glu]e in the rat striatum during anoxia. [Glu]e increased rapidly at 102+/-5.4s (n = 6) after the start of nitrogen inhalation. The increase continued for about 30 s, and then [Glu]e decreased. The peak value of delta[Glu]e was 141+/-37 micro M. [Glu]e subsequently underwent another gradual increase, reaching 213+/-69 microM at 15 min after the start of nitrogen inhalation. This distinct biphasic profile was reproducible. We conclude that this method is very useful for monitoring [Glu]e in the brain under low pO2 conditions.

Animals↗
PubMed1999

Differential response of non-transferrin bound iron uptake in rat liver cells on long-term and short-term treatment with iron.

BACKGROUND: Uptake of non-transferrin-bound iron by the liver is important as a clearance mechanism in iron overload. In contrast to physiological uptake via receptor-mediated endocytosis of transferrin, no regulatory mechanisms for this process are known. This study compares the influence of long-term and short-term depletion and loading of hepatocytes with iron on the uptake of non-transferrin bound iron, its affinity, specificity and the interaction with the transferrin-mediated pathways. METHODS: Rats were fed iron-deficient, normal and 3,5,5-trimethylhexanoyl-ferrocene-containing diets to obtain livers with the corresponding desired status and the hepatocytes from these livers were used for transport studies. Hepatocytes from normal rats were depleted or loaded with iron by short-term treatment with desferrioxamine or ferric ammonium citrate, respectively. Uptake of non-transferrin bound iron was assayed from ferric citrate and from ferric diethylene triammine pentaacetate. RESULTS: Uptake of non-transferrin-bound iron in hepatocytes could be seen as consisting of a high-affinity (Km=600 nM) and a low-affinity component. Whereas in normal and in iron-starved rats the high-affinity component was more prominent, it disappeared altogether in hepatocytes from rats with iron overload resulting from prolonged feeding with TMH-ferrocene-enriched diet. Overloading also led to loss of inhibition by diferric transferrin, which occured in starved as well as normal cells. In contrast, short-term iron-depletion of isolated hepatocytes with desferrioxamine had only a weak stimulatory effect, whereas treatment with ferric ammonium citrate strongly increased the uptake rates. However, the inhibition by diferric transferrin also disappeared. In both cases, uptake of non-transferrin bound iron was inhibited by apotransferrin. CONCLUSIONS: Non-transferrin bound iron uptake in liver cells is apparently regulated by the iron status of the liver. The mode of response to iron loading depends on the method of loading in terms of time course and the form of iron used. It cannot be explained by the behavior of the iron regulatory protein, and it is complex, seeming to involve more than one transport system.

Animal Feed↗
PubMedDate not supplied

Synthetic ferrocenic mefloquine and quinine analoguesas potential antimalarial agents.

A few years ago we proposed a strategy for the synthesis of new ferrocene-chloroquine analogues replacing the carbon chain of chloroquine by hydrophobic ferrocenyl moieties. Now, this strategy has been applied to the antimalarial amino-alcohols class to afford new potentially active analogues of mefloquine and quinine bearing a substituted ferrocenic group. The pathway used for the synthesis of the mefloquine analogues includes the coupling of an aminomethyl substituted ferrocene carboxaldehyde with a lithio quinoline compound. On the other hand, the synthesis of quinine analogues was ensured by the 'inverse' reaction of a lithio aminomethyl ferrocene with a quinoline carboxaldehyde. The configurations of each diastereoisomer were unambiguously determined by spectroscopic data. The mechanistic interpretations were fully discussed. Ferrocenyl analogues of mefloquine and quinine exhibited a lower antimalarial activity than mefloquine and quinine themselves. Comparing optical isomers, those isomers dissimilar to ferrocenyl derivatives presented better antimalarial activities than those similar to ferrocenyl.

Animals↗