A microwave-assisted extraction method combined with magnetic ionic liquid-based dispersive liquid-liquid microextraction for the extraction of chloramine-T from fish samples prior to its determination by high-performance liquid chromatography.

In the present work, a combination of microwave-assisted extraction with magnetic ionic liquid-based dispersive liquid-liquid microextraction was developed for the extraction of chloramine-T from fish samples. In this method, the sample was mixed with a hydrochloric acid solution and exposed to microwave irradiations. By doing so, chloramine-T was converted to p-toluenesulfonamide and extracted from the sample into an aqueous phase. Then, a mixture of acetonitrile (as a dispersive solvent) and magnetic ionic liquid (as an extraction solvent) was rapidly injected into the obtained solution. In the following, the magnetic solvent droplets including the extracted analytes were isolated from the aqueous solution in the presence of an external magnetic field and after diluting with acetonitrile injected into high-performance liquid chromatography equipped with a diode array detector. Under the optimum extraction conditions, high extraction recovery (78%), low limits of detection (7.2 ng/g) and quantification (23.9 ng/g), good repeatability (relative standard deviations ≤5.8 and 6.8% for intra- and inter-day precisions, respectively), and wide linear range (23.9-1000 ng/g) were obtained. Finally, various fish samples marketed in Tabriz city (East Azarbaijan, Iran) were analyzed with the suggested method.

Chloramine Trihydrate-Mediated Tandem Synthesis of New Pyrrole and/or Arene-Linked Mono- and Bis(1,3,4-Oxadiazole) Hybrids as Potential Bacterial Biofilm and MRSA Inhibitors.

A two-step tandem protocol was used to prepare new pyrrole and/or arene-linked bis(1,3,4-oxadiazoles) as well as their mono-analogs. The appropriate aldehydes and benzohydrazides were first condensed in ethanol at 80 °C to yield the corresponding N-benzoylhydrazones. Without isolation, the previous intermediates were subjected to a chloramine trihydrate-mediated oxidative cyclization in DMSO at 180 °C to yield the target molecules. The antibacterial potency of the (pyrrole-arene)-linked hybrids exceeded the arene-linked hybrids, and the bis(1,3,4-oxadiazoles) exceeded their mono-analogs against six different ATCC strains. Furthermore, the antibacterial efficacy of bis(1,3,4-oxadiazoles) 11c, and 11f, which are linked to pyrrole, and (p-tolylthio)methyl units, was highest against S. aureus, E. coli, and P. aeruginosa strains. Their MIC ranged between 3.8 and 3.9 µM, while their MBC values ranged between 7.7 and 15.8 µM. Additionally, they showed promising bacterial biofilm inhibitory activity against the same strains tested, with IC50 values ranging from 4.7 to 5.3 µM. They were also effective against MRSA ATCC : 33591, and ATCC : 43300 strains, with MIC, and MBC values ranging from 3.8-7.9 and 7.7-15.8 µM, respectively. When tested against the MCF-10A cell lines, hybrids 11c, and 11f are cytotoxic at concEntrations that are more than 6 and 13-fold higher than their MIC values against the S. aureus, E. coli, and P. aeruginosa strains, respectively. This lends support to both hybrids' potential as safe antibacterial agents.

Tandem synthesis, cytotoxicity, and in silico study of new 1,3,4-oxadiazoles as potential thymidylate synthase inhibitors.

A new series of pyrrole-linked mono- and bis(1,3,4-oxadiazole) hybrids, attached to various arene units, was prepared using a two-step tandem protocol. Therefore, a benzohydrazide derivative was condensed with the appropriate aldehydes in ethanol at 80°C for 60-150 min to give the corresponding N-(benzoylhydrazones). Without isolation, the previous intermediates underwent intramolecular oxidative cyclization in dimethyl sulfoxide at 180°C for 90-200 min in the presence of chloramine trihydrate to afford the target hybrids. The cytotoxicity of all hybrids was examined in vitro against the MCF-7, HEPG2, and Caco2 cell lines. Arene-linked hybrids 4i and 4j, attached to p-nitro and p-acetoxy units, were the most potent ones, with IC50 values ranging from 5.47 to 8.80 and 12.75 to 21.22 µM, respectively, when tested on the above cell lines. At the tested concentrations of 5 and 7.5 µM, hybrid 4i inhibited thymidylate synthase (TS) with the best inhibition percentages of 72.3 and 91.3, whereas hybrid 4j displayed comparable inhibitory activity to the reference pemetrexed. Hybrid 4j had inhibition percentages of 62.7 and 82.6, whereas pemetrexed had inhibition percentages of 59.2 and 80.2, respectively. The capability of hybrids 4i and 4j as potential TS inhibitors is supported by molecular docking studies, while SwissADME predicts their efficacy as drug-like scaffolds.

Study of Albumin Oxidation in COVID-19 Pneumonia Patients: Possible Mechanisms and Consequences.

Oxidative stress induced by neutrophils and hypoxia in COVID-19 pneumonia leads to albumin modification. This may result in elevated levels of advanced oxidation protein products (AOPPs) and advanced lipoxidation end-products (ALEs) that trigger oxidative bursts of neutrophils and thus participate in cytokine storms, accelerating endothelial lung cell injury, leading to respiratory distress. In this study, sixty-six hospitalized COVID-19 patients with respiratory symptoms were studied. AOPPs-HSA was produced in vitro by treating human serum albumin (HSA) with chloramine T. The interaction of malondialdehyde with HSA was studied using time-resolved fluorescence spectroscopy. The findings revealed a significantly elevated level of AOPPs in COVID-19 pneumonia patients on admission to the hospital and one week later as long as they were in the acute phase of infection when compared with values recorded for the same patients 6- and 12-months post-infection. Significant negative correlations of albumin and positive correlations of AOPPs with, e.g., procalcitonin, D-dimers, lactate dehydrogenase, aspartate transaminase, and radiological scores of computed tomography (HRCT), were observed. The AOPPs/albumin ratio was found to be strongly correlated with D-dimers. We suggest that oxidized albumin could be involved in COVID-19 pathophysiology. Some possible clinical consequences of the modification of albumin are also discussed.

Pretreatment Method for Chloramine-T Decon Sample Before GC Analysis of HD and VX.

Chloramine-T, especially its solution in weak acidity, is one of the decontaminants for chemical warfare agents (CWAs), HD, and VX. A high CWAs recovery from decontamination (decon) sample via pretreatment was essential for evaluating decontamination effects. This paper performed experiments to optimize pretreatment methods to extract residual CWAs from chloramine-T decon samples before GC analysis. Effects of two neutralization methods, destroying decon activity by 15% Na2SO3 or decreasing decon activity by 3% NH3·H2O or 4% NaOH, were studied. Results showed they were all suitable for the HD decon sample, but only 4% NaOH was ideal for the VX decon sample. As for extractant, compared with dichloromethane, petroleum ether was more suitable for recovering CWAs from decon samples. A high recovery above 80% could be obtained for HD and VX samples ranging from 10 mg/L to 10,000 mg/L when optimized neutralization and extraction methods were simultaneously carried out.

Oxidant-resistant LRRC8A/C anion channels support superoxide production by NADPH oxidase 1.

KEY POINTS: LRRC8A-containing anion channels associate with NADPH oxidase 1 (Nox1) and regulate superoxide production and tumour necrosis factor-α (TNFα) signalling. Here we show that LRRC8C and 8D also co-immunoprecipitate with Nox1 in vascular smooth muscle cells. LRRC8C knockdown inhibited TNFα-induced O2•- production, receptor endocytosis, nuclear factor-κB (NF-κB) activation and proliferation while LRRC8D knockdown enhanced NF-κB activation. Significant changes in LRRC8 isoform expression in human atherosclerosis and psoriasis suggest compensation for increased inflammation. The oxidant chloramine-T (ChlorT, 1 mM) weakly (∼25%) inhibited LRRC8C currents but potently (∼80%) inhibited LRRC8D currents. Substitution of the extracellular loop (EL1, EL2) domains of 8D into 8C conferred significantly stronger (69%) ChlorT-dependent inhibition. ChlorT exposure impaired subsequent current block by DCPIB, which occurs through interaction with EL1, further implicating external oxidation sites. LRRC8A/C channels most effectively sustain Nox1 activity at the plasma membrane. This may result from their ability to remain active in an oxidized microenvironment. ABSTRACT: Tumour necrosis factor-α (TNFα) activates NADPH oxidase 1 (Nox1) in vascular smooth muscle cells (VSMCs), producing superoxide (O2•- ) required for subsequent signalling. LRRC8 family proteins A-E comprise volume-regulated anion channels (VRACs). The required subunit LRRC8A physically associates with Nox1, and VRAC activity is required for Nox activity and the inflammatory response to TNFα. VRAC currents are modulated by oxidants, suggesting that channel oxidant sensitivity and proximity to Nox1 may play a physiologically relevant role. In VSMCs, LRRC8C knockdown (siRNA) recapitulated the effects of siLRRC8A, inhibiting TNFα-induced extracellular and endosomal O2•- production, receptor endocytosis, nuclear factor-κB (NF-κB) activation and proliferation. In contrast, siLRRC8D potentiated NF-κB activation. Nox1 co-immunoprecipitated with 8C and 8D, and colocalized with 8D at the plasma membrane and in vesicles. We compared VRAC currents mediated by homomeric and heteromeric LRRC8C and LRRC8D channels expressed in HEK293 cells. The oxidant chloramine T (ChlorT, 1 mM) weakly inhibited 8C, but potently inhibited 8D currents. ChlorT exposure also impaired subsequent current block by the VRAC blocker DCPIB, implicating external sites of oxidation. Substitution of the 8D extracellular loop domains (EL1, EL2) into 8C conferred significantly stronger ChlorT-mediated inhibition of 8C currents. Our results suggest that LRRC8A/C channel activity can be effectively maintained in the oxidized microenvironment expected to result from Nox1 activation at the plasma membrane. Increased ratios of 8D:8C expression may potentially depress inflammatory responses to TNFα. LRRC8A/C channel downregulation represents a novel strategy to reduce TNFα-induced inflammation.

3-Benzoylisoxazolines by 1,3-Dipolar Cycloaddition: Chloramine-T-Catalyzed Condensation of α-Nitroketones with Dipolarophiles.

In this study, 3-benzoylisoxazolines were synthesized by reacting alkenes with various α-nitroketones using chloramine-T as the base. The scope of α-nitroketones and alkenes is extensive, including different alkenes and alkynes to form various isoxazolines and isoxazoles. The use of chloramine-T, as the low-cost, easily handled, moderate base for 1,3-dipolar cycloaddition is attractive.

Chloramine-T-Mediated Oxidation of Benzylic Alcohols Using Indium(III) Triflate.

The efficient oxidation of benzylic alcohols to carbonyl compounds was performed using chloramine-T and a catalytic amount of indium(III) triflate. The primary benzylic alcohols were converted to the corresponding aldehydes in a good yield, and the secondary benzylic alcohols were oxidized to ketones in a high yield. The optimized reaction conditions required 0.3 eq of indium(III) triflate and the use of acetonitrile as a solvent.

Photoacoustic calorimetry studies of CO photo-dissociation from chloramine-T modified horse heart cytochrome-c.

Treatment of horse heart Cytochrome-c (Cc) with N-chloro-4-toluosulfonamide (Chloramine-t, CT) results in the oxidation of methionine (Met) residues to the corresponding sulfoxide including the distal heme ligand, Met80. The resulting Fe-sulfoxide coordination is sufficiently labile in the ferrous form to be displaced by gaseous ligands, including CO. Photolysis of the CO-CT-Cc complex provides an opportunity to examine ligand binding dynamics that are associated with a relatively rigid distal heme pocket. In this work, photoacoustic calorimetry (PAC) was utilized to obtain the kinetics as well as enthalpy and molar volume changes subsequent to CO photo-dissociation from CO-CT-Cc. Previous photolysis studies of CO-CT-Cc have led to a proposed model for ligand recombination in which the Met80-sulfoxide and CO recombine with the heme on relatively slow timescales (50 µs and ∼500 µs, respectively). The PAC data presented here reveals two additional kinetic phases with lifetimes of <20 ns and 534 ± 75 ns. The fast phase (<20 ns) is associated with an ΔH of 44 ± 5 kcal mol-1 and ΔV of -0.5 ± 0.5 mL mol-1, whereas the slower phase (534 ns) is associated with a small ΔH of 2 ± 3 kcal mol-1 and ΔV of 1 ± 0.5 mL mol-1.

Prick testing with chemicals in the diagnosis of occupational contact urticaria and respiratory diseases.

BACKGROUND: Little is known about the use of prick tests with chemicals in diagnosing occupational diseases. OBJECTIVE: To evaluate the use of prick tests in the diagnosis of occupational contact urticaria, asthma and rhinitis caused by chemicals (undertaken at the Finnish Institute of Occupational Health). MATERIAL AND METHODS: We retrospectively reviewed the patient and test files for the period 1 January 1991 to 31 May 2011. Prick tests were performed with chemical solutions and human serum albumin (HSA)-chemical conjugates. RESULTS: Positive prick test reactions to isocyanate-HSA conjugates were associated with isocyanate-specific IgE in all 20 patients, and 17 patients had a relevant occupational disease. Positive reactions to chloramine-T-HSA conjugates in 10 patients also indicated the presence of specific IgE, although occupational diseases were not always diagnosed. Eleven of 17 patients with positive reactions to persulfate solutions were diagnosed with an occupational disease. Methacrylates, colophonium-related substances, amine hardeners, ethanolamines, glutaraldehyde, glyoxal, pyrocatechol and ammonium thioglycolate did not elicit any relevant prick test reactions. No generalized reactions were detected. CONCLUSION: Prick tests can be safely used for diagnosing contact urticaria, asthma and rhinitis caused by isocyanates, chloramine-T, persulfates, and chlorhexidine, but the results should be carefully interpreted and related to clinical symptoms and other diagnostic tests.

Novel pyrazole integrated 1,3,4-oxadiazoles: synthesis, characterization and antimicrobial evaluation.

A novel series of 2-(5-methyl-1,3-diphenyl-1H-pyrazol-4-yl)-5-phenyl-1,3,4-oxadiazoles 7(a-m) were synthesized either by cyclization of N'-benzoyl-5-methyl-1,3-diphenyl-1H-pyrazole-4-carbohydrazide 4a using POCl3 at 120°C or by oxidative cyclization of hydrazones derived from various arylaldehyde and (E)-N'-benzylidene-5-methyl-1,3-diphenyl-1H-pyrazole-4-carbohydrazide 5(a-d) using chloramine-T as oxidant. Newly synthesized compounds were characterized by analytical and spectral (IR, (1)H NMR, (13)C NMR and LC-MS) methods. The synthesized compounds were evaluated for their antimicrobial activity and were compared with standard drugs. The compounds demonstrated potent to weak antimicrobial activity. Among the synthesized compounds, compound 7m emerged as an effective antimicrobial agent, while compounds 7d, 7f, 7i and 7l showed good to moderate activity. The minimum inhibitory concentration of the compounds was in the range of 20-50µgmL(-1) against bacteria and 25-55µgmL(-1) against fungi. The title compounds represent a novel class of potent antimicrobial agents.

Impacts of chloramine-T treatment on antioxidant enzyme activities and genotoxicity in rainbow trout, Oncorhynchus mykiss (Walbaum).

Juvenile rainbow trout Oncorhynchus mykiss (Walbaum) were exposed to therapeutic, and higher concentrations of chloramine-T (Cl-T) to assess the effects of this chemical on the antioxidant enzyme system and genetic structure. Red blood cells acetylcholinesterase, ∆-aminolevulinic acid dehydratase, paraoxonase and liver glutathione S-transferase activity were increased at 10 and 20 mg L(-1) Cl-T-exposed fish, while they were decreased at 30 mg L(-1) Cl-T-exposed fish. On the other hand, liver catalase activity and liver protein levels increased at 10 mg L(-1) and decreased at 20 and 30 mg L(-1) concentrations of Cl-T. Liver super-oxide dismutase activity decreased at 10 mg L(-1) and 20 mg L(-1) Cl-T and increased at 30 mg L(-1) of Cl-T. Compared to control, comet assay indicated that Cl-T did not cause significant DNA damage to red blood cells of the fish. Results indicate that 10 or 20 mg L(-1) Cl-T can be safely used to prevent or treat external parasitic and bacterial infection of rainbow trout.

Microbiota of laboratory channel catfish skin mucosa and aquaria water exposed to chloramine-T trihydrate.

Here, we describe the skin mucosa microbiome of channel catfish (Ictalurus punctatus) before and after exposure to chloramine-T trihydrate. We also describe the aquaria water microbiome after the post-treatment period. These data provide a unique baseline description of skin mucosa and aquaria water microbiome from catfish reared in research aquaria.

The in-vitro development of novel enzyme-based chemo-mechanical caries removal agents.

OBJECTIVES: Bromelain is a potent proteolytic enzyme that has a unique functionality makes it valuable for various therapeutic purposes. This study aimed to develop three novel formulations based on bromelain to be used as chemomechanical caries removal agents. METHODS: The novel agents were prepared using different concentrations of bromelain (10-40 wt. %), with and without 0.1-0.3 wt. % chloramine T or 0.5-1.5 wt. % chlorhexidine (CHX). Based on the enzymatic activity test, three formulations were selected; 30 % bromelain (F1), 30 % bromelain-0.1 % chloramine (F2) and 30 % bromelain-1.5 % CHX (F3). The assessments included molecular docking, Fourier-transform infrared spectroscopy (FTIR), viscosity and pH measurements. The efficiency of caries removal was assessed by DIAGNOdent pen, measuring the excavation time and number of applications, followed by a morphological evaluation of the remaining dentine using scanning electron microscopy (SEM). The results were compared to Brix 3000 as a control. RESULTS: The chloramine and chlorhexidine were chemically compatible with bromelain without compromising the enzyme activity. All experimental formulations showed higher viscosity and pH in comparison to Brix 3000. The DIAGNOdent readings were <20 in all groups, and the lowest readings were observed in F2. The excavation time and number of applications were lowest in F2 and F1. Both F2 and F3 produced smooth dentine surfaces with less tissue debris, but more patent dentine tubules were observed in F1 and F2. CONCLUSIONS: The bromelain-contained formulations showed a potential to be used as chemomechanical caries removal agents in vitro. Further laboratory and clinical studies are needed to validate this claim. CLINICAL SIGNIFICANCE: The bromelain from pineapple stem has broad specificity for cleavage the peptide bonds in denatured protein to facilitate their removal. The study proved the efficiency of this enzyme to remove the dental caries chemomechanically when used alone or conjugated with chloramine and/or chlorhexidine to enhance the disinfecting and cleansing properties.

Evaluation of Effective Chloramine-T Concentration to Be Incorporated in Dental Stone for Antimicrobial Activity.

Objective The objective of this study was to determine the antimicrobial activity of type III gypsum at three different chloramine-T concentrations and to ascertain the most effective concentration to be added for optimum inhibitory activity against Candida albicans. Method Ten discs of type III gypsum were fabricated for each group. Standard type III gypsum without any disinfectant was used for the control group. For the experimental group, an admixture of chloramine-T and standard dental stone was employed in varying w/w concentrations (0.1%, 0.25%, and 0.5%). Discs were placed in a petri dish containing Sabouraud dextrose agar lawned with Candida albicans culture and incubated for 24 hours. The zone of inhibition created around the discs was measured and evaluated. Result The mean zone of inhibition (mean ± standard deviation) in the control group was 0 mm; 0.70±1.05 mm in group 1 (0.1% w/w concentration), 2.70 ± 2.35 mm in group 2 (0.25% w/w concentration), and 20.80 ± 1.68 mm in group 3 (0.5% w/w concentration). A one-way ANOVA test showed that there was a significant difference in the inhibition zone created around all groups (p < 0.05), with the discs of group 3 yielding the most positive results. Conclusion The addition of 0.5% chloramine-T to type III gypsum showed the most promising result, out of the concentrations tested, as a self-disinfecting dental stone and could be used for further investigations.

Role of amino acid oxidation and protein unfolding in peroxyl radical and peroxynitrite-induced inactivation of glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides.

The mechanisms underlying the inactivation of Leuconostoc mesenteroides glucose 6-phosphate dehydrogenase (G6PDH) induced by peroxyl radicals (ROO●) and peroxynitrite (ONOO-), were explored. G6PDH was incubated with AAPH (2,2' -azobis(2-methylpropionamidine)dihydrochloride), used as ROO● source, and ONOO-. Enzymatic activity was assessed by NADPH generation, while oxidative modifications were analyzed by gel electrophoresis and liquid chromatography (LC) with fluorescence and mass detection. Changes in protein conformation were studied by circular dichroism (CD) and binding of the fluorescent dye ANS (1-anilinonaphthalene-8-sulfonic acid). Incubation of G6PDH (54.4 µM) with 60 mM AAPH showed an initial phase without significant changes in enzymatic activity, followed by a secondary time-dependent continuous decrease in activity to ∼59% of the initial level after 90 min. ONOO- induced a significant and concentration-dependent loss of G6PDH activity with ∼46% of the initial activity lost on treatment with 1.5 mM ONOO-. CD and ANS fluorescence indicated changes in G6PDH secondary structure with exposure of hydrophobic sites on exposure to ROO●, but not ONOO-. LC-MS analysis provided evidence for ONOO--mediated oxidation of Tyr, Met and Trp residues, with damage to critical Met and Tyr residues underlying enzyme inactivation, but without effects on the native (dimeric) state of the protein. In contrast, studies using chloramine T, a specific oxidant of Met, provided evidence that oxidation of specific Met and Trp residues and concomitant protein unfolding, loss of dimer structure and protein aggregation are involved in G6PDH inactivation by ROO●. These two oxidant systems therefore have markedly different effects on G6PDH structure and activity.

Nanocomposite matrix conjugated with carbon nanomaterials for photocatalytic wastewater treatment.

The problem of hazardous wastewater remediation is a complicated issue and a global challenge. Herein, a layered Co0.5Ni0.5Fe2O4/SiO2/TiO2 composite matrix was prepared and incorporated with three carbon nanomaterials having different dimensionalities, carbon dots (C-dots, 0D), single-walled carbon nanotubes (1D), and reduced graphene oxide (2D), in an effort to create effective photocatalytic nanocomposites for chloramine-T removal from water. Microstructural analyses confirmed the formation of nanocomposites and revealed their chemistry and structure. Elemental mapping revealed a uniform distribution of elements throughout the nanocomposite matrix that was free of impurities. The spherical shape of the matrix particles (average diameter ~90 nm) and their conjugation with the carbon nanomaterials were confirmed. Nitrogen adsorption-desorption isotherms revealed that the nanocomposites were mesoporous but also contained macropores. The surface chemical compositions of the nanocomposites were investigated and showed a range of available binding energies. The kinetics of photocatalysis by the system were studied, and the effects of different parameters (such as photocatalyst dose and charge-carrier scavengers) on the efficiency of chloramine-T degradation were also investigated. The nanocomposite loaded with 10% C-dots exhibited high UV-assisted photocatalytic activity for chloramine-T degradation (65% removal efficiency).

Antibacterial Effect of Endodontic Disinfections on Enterococcus Faecalis in Dental Root Canals-An In-Vitro Model Study.

Enterococcus faecalis (E. faecalis) is rather unsusceptible to many root canal disinfections which often cause a therapeutic problem. Therefore, the present in vitro study observed the efficiency of different endodontic antiseptics in their capability to suppress E. faecalis, especially inside dentinal tubules. Prior to any testing, root canals of extracted third human molars were inoculated with E. faecalis for 48 h. Antiseptic dressings with chloramine-T or calcium hydroxide (CaOH) for 24 h or irrigations with 1.3% sodium hypochlorite (NaOCl) were applied with n = 10 in each group. As control irrigation with normal saline was used. All treated canals were manually enlarged from size ISO 50 to 110 and the ablated dentin debris was subjected to microbial culture analysis. Bacterial colonization of the dentinal tubules up to 300 µm was verified by scanning electron microscopy and histological sample preparation. Application of crystalline chloramine-T caused total bacterial suppression inside the dentinal tubules. Dressings with CaOH showed only minor effects. Irrigation with NaOCl caused total eradication of bacteria adhering to the root canal walls, but also failed to completely suppress E. faecalis inside the dentinal tubules. The study showed that chloramine-T is of strong antiseptic activity and also efficient in suppressing E. faecalis inside dentinal tubules.

Synthesis, stability, and cellular uptake of 131I-estradiol against MCF7 and T-47D human cell lines as a radioligand for binding assay.

Estradiol is a steroid hormone that works as an agonist estrogen receptor (ER). This compound is widely used as a ligand and bind specifically to the ERα. Radioligand binding assay is an in vitro method for drug development from natural products by synthesizing estradiol through radiolabeling using the radioiodination method. Synthesis of 131I-estradiol was perfomed by direct method using chloramine T as an oxidizer and by indirect labeling using 131I-histamine. The purity of chemical was determined by thin-layer chromatography and paper electrophoresis, as well as its stability for 30 days of storage in refrigerator, freezer and room temperature. The cellular uptake test of the radioligands from both methods was carried out with MCF7 and T-47D cell lines at 60 min. The results exhibited that 131I-estradiol was succesfully obtained with radiochemical purity greater than 95% and more stable in the refrigerator until 21 days than freezer and room temperature. 131I-estradiol and 131I-his-estradiol were internalized higher in T-47D cells than MCF7 cells (44.34 ± 5.93% vs. 17.27 ± 1.71% and 45.34 ± 6.42% vs. 4.92 ± 1.59%, respectively). Furthermore, the radioligands can be used to binding assay in determining the agonist or antagonist to ER of new drugs development.