• Journal of Radiopharmaceuticals and Molecular Probes
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• v.5 no.2
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• pp.129-134
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• 2019

Over a few decades, copper radioisotopes and their chelation chemistry for radiopharmaceuticals have played crucial role in the radiopharmaceutical science area. A variety of chelators have been required for their stable targeting ability in physiological conditions. For radiolabeling with copper-64 into biomolecules, thermodynamic stability, kinetic inertness, pH stability, and redox stability should be considered. In this regard, many researchers have attempted to develop the chelators that can bind with copper more tightly, rapidly and stably for copper radiolabeling. This review discusses the chemistry of copper, its suitable chelators and characteristics, while elucidating the evaluations of each chelator for radiolabeling.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.2 no.1
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• pp.22-36
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• 2016

$^{68}Ga$ is a promising radionuclide for positron emission tomography (PET). It is a generator-produced ($^{68}Ge/^{68}Ga$-generator) radionuclide with a half-life of 68 min. The employment of $^{68}Ga$ for basic research and clinical applications is growing exponentially. Bifunctional chelators (BFCs) that can be efficiently radiolabeled with $^{68}Ga$ to yield complexes with good in vivo stability are needed. Given the practical advantages of $^{68}Ga$ in PET applications, gallium complexes are gaining increasing attention in biomedical imaging. However, new $^{68}Ga$-labeled radiopharmaceuticals that can replace $^{18}F$-labeled agents like [$^{18}F$]fluorodeoxyglucose (FDG) are needed. The majority of $^{68}Ga$-labeled derivatives currently in use consist of peptide agents, but the development of other agents, such as amino acid or nitroimidazole derivatives and glycosylated human serum albumin, is being actively pursued in many laboratories. Thus, the availability of new $^{68}Ga$-labeled radiopharmaceuticals with high impact is expected in the near future. Here, we present an overview of the different new classes of chelators for application in molecular imaging using $^{68}Ga$ PET.

• Nutrition Research and Practice
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• v.1 no.1
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• pp.29-35
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• 2007

Trace mineral studies involving metal ion chelators have been conducted in investigating the response of gene and protein expressions of certain cell lines but a few had really focused on how these metal ion chelators could affect the availability of important trace minerals such as Zn, Mn, Fe and Cu. The aim of the present study was to investigate the availability of Zn for the treatment of MC3T3-E1 osteoblast-like cells and the availability of some trace minerals in the cell culture media components after using chelexing resin in the FBS and the addition of N,N,N',N'-tetrakis-(2-pyridylmethyl)ethylenediamine (TPEN, membrane-permeable chelator) and diethylenetriaminepentaacetic acid (DTPA, membrane-impermeable chelator) in the treatment medium. Components for the preparation of cell culture medium and Zn-treated medium have been tested for Zn, Mn, Fe and Cu contents by atomic absorption spectrophotometer or inductively coupled plasma spectrophotometer. Also, the expression of bone-related genes (ALP, Runx2, PTH-R, ProCOL I, OPN and OC) was measured on the cellular Zn depletion such as chelexing or TPEN treatment. Results have shown that using the chelexing resin in FBS would significantly decrease the available Zn (p<0.05) $(39.4{\pm}1.5{\mu}M\;vs\;0.61{\pm}10.15{\mu}M)$ and Mn (p<0.05) $(0.74{\pm}0.01{\mu}M\;vs\;0.12{\pm}0.04{\mu}M)$. However, levels of Fe and Cu in FBS were not changed by chelexing FBS. The use of TPEN and DTPA as Zn-chelators did not show significant difference on the final concentration of Zn in the treatment medium (0, 3, 6, 9, $12{\mu}M$) except for in the addition of higher $15{\mu}M\;ZnCl_2$ which showed a significant increase of Zn level in DTPA-chelated treatment medium. Results have shown that both chelators gave the same pattern for the expression of the five bone-related genes between Zn and Zn+, and TPEN-treated experiments, compared to chelex-treated experiment, showed lower bone-related gene expression, which may imply that TPEN would be a stronger chelator than chelex resin. This study showed that TPEN would be a stronger chelator compared to DTPA or chelex resin and TPEN and chelex resin exerted cellular zinc depletion to be enough for cell study for Zn depletion.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.445.1-445
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• 2001

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2002.05a
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• pp.89-89
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• 2002

• Korean Journal of Clinical Laboratory Science
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• v.43 no.2
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• pp.33-42
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• 2011

Zinc plays a key role in genetic expression, cell division, and cell growth and is essential for the functions of more than 450 metalloenzyme. There are high concentrations of zinc in pigment epithelium in bullfrog eye. Zinc deficiency causes night blindness and abnormal dark adaptation. The purpose of this study was to identify ERG (electroretinogram) b-wave sensitivity during light and dark adaptation in bullfrog retina after zinc and zinc chelators treatment such as histidine and TSQ (N-(6-methoxy-8-qunolyl)-p-toluenesulfon amide). Especially, we focused whether histidine act as a zinc chelator in the Muller cell. The results of our study are summarized as follows: 1) Both zinc and histidine elevated ERG b-wave amplitude and threshold in Muller cells by accelerating rhodopsin regeneration time and increased a-peak absorbance during light adaptation. 2) TSQ reduced those by prolonging rhodopsin regeneration time and decrement of a-peak absorbance during light adaptation. 3) Zinc shortened rhodopsin regeneration time and prolonged a-peak absorbance. These results suggested that histidine may act as a zinc-mediated transporter in presynaptic Muller cell membrane rather than zinc chelator and acts as a GABA-receptor inhibitor which blocks $Cl^-$ influx to the postsynapse.

• Journal of the Korean Society of Clothing and Textiles
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• v.28 no.7
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• pp.873-881
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• 2004

This research was aimed to investigate the effect of enzyme and the addition of chelators on rotting of the Kenaf bast. Enzyme rotting was effective only when the chelators were added with the enzyme. EDTA was a more effective chelator than oxalic acid under 1% concentration. There was no difference in the rotting effect under different enzyme concentration levels, and under different treatment time and temperature. Therefore, it was found that enzyme rotting can be carried out with low enzyme concentration(0.125%) at room temperature. Retting time can be shortened when higher enzyme concentration and higher temperature are applied. Cellulose I structure of kenaf fiber did not change after enzyme rotting, and different enzyme concentration did not affect the crytallinity structure. Non-cellulosic matters such as hemicellulose, lignin, and pectin were present in the descending order in the enzyme rotted kenaf fiber, and there were no differences in their amounts due to enzyme concentration levels. There was no difference in the dyeabilities of kenaf fiber rotted with different enzyme concentration levels. Enzyme rotted kenaf fiber showed better cyeability when pectin, lignin, and hemicellulose were removed.

• Toxicological Research
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• v.33 no.4
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• pp.299-304
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• 2017

Thallium and its compounds are a class of highly toxic chemicals that cause wide-ranging symptoms such as gastrointestinal disturbances; polyneuritis; encephalopathy; tachycardia; skin eruptions; hepatic, renal, cardiac, and neurological toxicities; and have mutagenic and genotoxic effects. The present research aimed to evaluate the efficacy of the chelating agents deferasirox (DFX) and deferiprone (L1) in reducing serum and tissue thallium levels after the administration of thallium (III), according to two different dosing regimens, to several groups of Wistar rats for 60 days. It was hypothesized that the two chelators might be more efficient as a combined therapy than as monotherapies in removing thallium (III) from the rats' organs. The chelators were administered orally as either single or combined therapies for a period of 14 days. Serum and tissue thallium (III) and iron concentrations were determined by flame atomic absorption spectroscopy. Serum and tissue thallium (III) levels were significantly reduced by combined therapy with DFX and L1. Additionally, iron concentrations returned to normal levels and symptoms of toxicity decreased.

• Korean Journal of Materials Research
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• v.31 no.10
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• pp.569-575
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• 2021

The reactivity evaluation of copper is performed using ethylenediamine, aminoethanol, and piperidine to apply organic chelators to copper etching. It is revealed that piperidine, which is a ring-type chelator, has the lowest reactivity on copper and copper oxide and ethylenediamine, which is a chain-type chelator, has the highest reactivity via inductively coupled plasma-mass spectroscopy (ICP-MS). Furthermore, it is confirmed that the stable complex of copper-ethylenediamine can be formed during the reaction between copper and ethylenediamine using nuclear magnetic resonance (NMR) and radio-thin layer chromatography. As a final evaluation, the copper reactivity is evaluated by wet etching using each solution. Scanning electron micrographs reveal that the degree of copper reaction in ethylenediamine is stronger than that in any other chelator. This result is in good agreement with the evaluation results obtained by ICP-MS and NMR. It is concluded that ethylenediamine is a prospective etch gas for the dry etching of the copper.

• Natural Product Sciences
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• v.27 no.2
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• pp.78-85
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• 2021

Through bio-guided isolation, two natural iron chelators were isolated from Mangifera indica L. leaves, identified as mangiferin (1) and iriflophenone-3-C-𝛽-D-glucoside (2). Their iron-chelating activity was compared to that of Desferal^® using bipyridyl assay and EDTA as a standard. Mangiferin showed the highest activity with IC₅₀ value of 0.385 mM (162.85 ㎍/mL). Furthermore, two combinations of mangiferin with Desferal^® (M-D) and iriflophenone-3-C-𝛽-D-glucoside (M-I) were evaluated. The results showed that mangiferin potentiated the iron chelation activity of Desferal^® about 46%, also that M-I combination is a promising candidate formula for iron chelation therapy. In addition, mangiferin and Desferal-iron complexes were prepared and characterized by IR, UV, and Mass spectra to compare their mode of chelation to iron. Their structural stability was studied by DFT calculations. Furthermore, they displayed increased ABTS antioxidant activity when bound to iron as compared to their free form, which enhances their pharmacological importance.