Equilibrium Studies of Iron (III) Complexes with Either Pyrazine, Quinoxaline, or Phenazine and Their Catecholase Activity in Methanol.

Currently, catalysts with oxidative activity are required to create valuable chemical, agrochemical, and pharmaceutical products. The catechol oxidase activity is a model reaction that can reveal new oxidative catalysts. The use of complexes as catalysts using iron (III) and structurally simple ligands such as pyrazine (pz), quinoxaline (qx), and phenazine (fz) has not been fully explored. To characterize the composition of the solution and identify the abundant species which were used to catalyze the catechol oxidation, the distribution diagrams of these species were obtained by an equilibrium study using a modified Job method in the HypSpec software. This allows to obtain also the UV-vis spectra calculated and the formation constants for the mononuclear and binuclear complexes with Fe3+ including: [Fe(pz)]3+, [Fe2(pz)]6+, [Fe(qx)]3+, [Fe2(qx)]6+, [Fe(fz)]3+, and [Fe2(fz)]6+. The formation constants obtained were log ß110 = 3.2 ± 0.1, log ß210 = 6.9 ± 0.1, log ß110 = 4.4 ± 0.1, log ß210 = 8.3 ± 0.1, log ß110 = 6.4 ± 0.2, and log ß210 = 9.9 ± 0.2, respectively. The determination of the catechol oxidase activity for these complexes did not follow a traditional Michaelis-Menten behavior.

Microbiome and oral squamous cell carcinoma: a possible interplay on iron metabolism and its impact on tumor microenvironment.

There is increasing evidence showing positive association between changes in oral microbiome and the occurrence of oral squamous cell carcinoma (OSCC). Alcohol- and nicotine-related products can induce microbial changes but are still unknown if these changes are related to cancerous lesion sites. In an attempt to understand how these changes can influence the OSCC development and maintenance, the aim of this study was to investigate the oral microbiome linked with OSCC as well as to identify functional signatures and associate them with healthy or precancerous and cancerous sites. Our group used data of oral microbiomes available in public repositories. The analysis included data of oral microbiomes from electronic cigarette users, alcohol consumers, and precancerous and OSCC samples. An R-based pipeline was used for taxonomic and functional prediction analysis. The Streptococcus spp. genus was the main class identified in the healthy group. Haemophilus spp. predominated in precancerous lesions. OSCC samples revealed a higher relative abundance compared with the other groups, represented by an increased proportion of Fusobacterium spp., Prevotella spp., Haemophilus spp., and Campylobacter spp. Venn diagram analysis showed 52 genera exclusive of OSCC samples. Both precancerous and OSCC samples seemed to present a specific associated functional pattern. They were menaquinone-dependent protoporphyrinogen oxidase pattern enhanced in the former and both 3',5'-cyclic-nucleotide phosphodiesterase (purine metabolism) and iron(III) transport system ATP-binding protein enhanced in the latter. We conclude that although precancerous and OSCC samples present some differences on microbial profile, both microbiomes act as "iron chelators-like" potentially contributing to tumor growth.

Non-enzymatic electrochemical determination of creatinine using a novel screen-printed microcell.

A low-cost and disposable microcell was constructed with a screen-printed electrode for the non-enzymatic electrochemical determination of creatinine. The working electrode was modified with carbon black and maintained in contact with paper-adsorbed iron (III) ions. A small sample volume of 3 µL was required for the device operation. Then, iron (III) ions were complexed in the presence of creatinine in a chemical step, followed by an electrochemical reduction of non-complexed metallic ions in excess. Cyclic voltammetry and differential-pulse voltammetry experiments were employed for the electrochemical characterizations and analytical performance evaluation of the microcell. The working electrode modification with carbon black provided a significant increase of analytical signal. The sensor presented a linear response for creatinine concentrations ranging from 0.10 to 6.5 mmol L-1, with a limit of detection of 0.043 mmol L-1. Experiments for creatinine determination in real samples were successful performed through of standard recovery in urine.

Data on study of hematite nanoparticles obtained from Iron(III) oxide by the Pechini method.

This article presents the data on α-Fe2O3 nanoparticles synthesized via Pechini method using iron(III) oxide precursor from steel industry. It is important to highlight the added value that is given to an industrial waste. The samples were characterized by thermal analysis (DTA, TG), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The TG showed three mass changes, whereas DTA resulted in three anomalies. X-ray diffraction pattern of the samples disclosed rhombohedral structure characteristic of the nanocrystalline α-Fe2O3 phase. The crystallite size was estimated for each thermal treatment. Fourier transform infrared spectroscopy confirms the phase purity of prepared nanoparticles. A detailed study on the local structure of the samples was carry out in the region of 800 and 400 cm-1, where the associated bands of Fe-O bonds are presents. The data have not been reported nor discussed for now.

Spectroscopic Studies on the Interaction of Metallic Ions with an Imidazolyl-Phenolic System.

A fluorescent imidazolyl-phenolic compound was applied on the detection of metallic species (Cu(2+), Al(3+), Cr(3+) and Fe(3+)) in a CH3CN/H2O (95/5, v/v) media. The presence and concentration of these cations altered significantly the emission profile of the probe, mainly lowering the signal intensity at 466 nm, while a new emission band around 395 nm appeared (for the trivalent ions). These results were rationalized as a combination of collisional quenching (KSV in the 10(3)-10(4) L mol(-1) range) and formation of a coordinated compound. The later disrupts the Excited State Intramolecular Proton Transfer that regulates the keto-enol tautomerism originally present on the free probe. Since the quenching efficiency and the obtained emission profiles are drastically different for Cu(2+) and Fe(3+) ions, this allows their differential recognition.

Using IR and Raman spectra to explain the catalytic activity of the Fe(II)/Fe(III) pair toward the cleavage of peptide bonds.

IR and Raman experiments of formamide (FA) solutions containing variable amounts of Fe(II) and Fe(III) salts were carried out. The νCO vibration is downshifted whereas the νCN mode is upshifted in the presence of the divalent ion. As the trivalent ion is added to the solvent, upshifts of both νCO and νCN vibrations are observed. These spectral patterns are related to the distinct FA forms that are stabilized by each ion. Fe(II) is surrounded by 6 ionic FA species while neutral ones coordinate to the trivalent ion with formation of [Fe(FA)3Cl](2+) and [Fe(FA)2(Cl)2](+). In higher salt compositions [FeCl4](-) is also identified in the spectra. Our vibrational results are very well corroborated by biological studies on the catalytic activity of the Fe(II)/Fe(III) pair in oxidative cleavage processes of polypeptides and proteins.

Synthesis, characterization, hydrolase and catecholase activity of a dinuclear iron(III) complex: Catalytic promiscuity.

Herein, we report the synthesis and characterization of the new di-iron(III) complex [(bbpmp)(H2O)(Cl)Fe(III)(µ-Ophenoxo)Fe(III)(H2O)Cl)]Cl (1), with the symmetrical ligand 2,6-bis{[(2-hydroxybenzyl)(pyridin-2-yl)methylamino]methyl}-4-methylphenol (H3bbpmp). Complexes 2 with the unsymmetrical ligand H2bpbpmp - {2-[[(2-hydroxybenzyl)(2-pyridylmethyl)]aminomethyl]-6-bis(pyridylmethyl) aminomethyl}-4-methylphenol and 3 with the ligand L(1)=4,11-dimethyl-1,8-bis{2-[N-(di-2-pyridylmethyl)amino]ethyl}cyclam were included for comparison purposes. Complex 1 was characterized through elemental analysis, X-ray crystallography, magnetochemistry, electronic spectroscopy, electrochemistry, mass spectrometry and potentiometric titration. The magnetic data show a very weak antiferromagnetic coupling between the two iron centers of the dinuclear complex 1 (J=-0.29cm(-1)). Due to the presence of labile coordination sites in both iron centers the hydrolysis of both the diester model substrate 2,4-BDNPP and DNA was studied in detail. Complex 1 was also able to catalyze the oxidation of the substrate 3,5-di-tert-butylcatechol (3,5-DTBC) to give the corresponding quinone, and thus it can be considered as a catalytically promiscuous system.

Bioactivity of pyridine-2-thiolato-1-oxide metal complexes: Bi(III), Fe(III) and Ga(III) complexes as potent anti-Mycobacterium tuberculosis prospective agents.

In the search for new therapeutic tools against tuberculosis and to further address the therapeutic potential of pyridine-2-thiol 1-oxide (Hmpo) metal complexes, two new octahedral [M(III)(mpo)3] complexes, with M = Ga or Bi, were synthesized and characterized in the solid state and in solution. Attempts to crystallize [Ga(III)(mpo)3] in CH2Cl2 led to single crystals of the reaction product [GaCl(mpo)2], where the gallium(III) ion is in a square basis pyramidal environment, trans-coordinated at the basis to two pyridine-2-thiolato 1-oxide anions acting as bidentate ligands through their oxygen and sulfur atoms. The biological activity of the new [M(III)(mpo)3] complexes together with that of the previously reported Fe(III) analogous compound and the pyridine-2-thiol 1-oxide sodium salt (Na mpo) was evaluated on Mycobacterium tuberculosis. The compounds showed excellent activity, both in the standard strain H37Rv ATCC 27294 (pan-susceptible) and in five clinical isolates that are resistant to the standard first-line anti-tuberculosis drugs isoniazid and rifampicin. These pyridine-2-thiol 1-oxide derivatives are promising compounds for the treatment of resistant tuberculosis.

Determinação de ferro (III) em produtos farmacêuticos por titulação fotométrica / Determination of iron (III) in pharmaceutical products by photometric titration

Este trabalho descreve a montagem de um sistema de titulação fotométrica simples e de baixo custo para a determinação de ferro (III) em produtos farmacêuticos. O sistema de titulação fotométrica foi construído utilizando-se a bomba peristáltica de um espectrofotômetro convencional. O procedimento é baseado na titulação de ferro (III) com EDTA e ácido salicílico como indicador. A absorção do complexo ferro (III)-ácido salicílico foi monitorada espectrofotometricamente em 525 nm. O limite de quantificação foi de 5 µg de ferro (III). O procedimento de titulação fotométrica foi aplicado para a determinação de ferro (III) em amostras contendo sulfato ferroso e hidróxido férrico polimaltosado. O procedimento mostrou sensibilidade, reprodutibilidade e precisão para a utilização em análise rotineira de ferro (III) em produtos farmacêuticos.

This paper describes a simple, precise and low-cost photometric titration method for iron (III) determination in pharmaceutical preparations. The photometric titration system was constructed using the peristaltic pump of a conventional spectrophotometer. The method is based on titration of iron (III) with EDTA using salicylic acid as indicator. The absorption of the iron (III)-salicylic acid complex was monitored spectrophotometrically at 525 nm. The limit of quantification was 5 µg of iron (III). The photometric titration procedure was applied for the determination of iron (III) in samples of ferrous sulfate and ferric hydroxide polymaltose complex. The procedure showed sensibility, reproducibility and accuracy for use as a method for the routine analysis of iron (III) in pharmaceutical formulations.

Avaliação da eficácia do uso intravenoso de sacarato de hidróxido de ferro III no tratamento de pacientes adultos com anemia ferropriva / Evaluation of the efficacy of intravenous iron III-hydroxide saccharate for treating adult patients with iron deficiency anemia

O objetivo desse estudo foi avaliar a eficácia do uso intravenoso de sacarato de hidróxido de ferro III no tratamento de pacientes adultos com anemia ferropriva. No período de janeiro de 2003 a dezembro de 2005, estudamos cinqüenta pacientes com anemia ferropriva que apresentaram intolerância e/ou resposta inadequada ao tratamento com ferro por via oral e/ou valor de hemoglobina inferior a 7,0 g/dL. Os principais exames laboratoriais realizados foram: hemograma completo, contagem de reticulócitos, ferro sérico, capacidade total de ligação de ferro e ferritina sérica. Os pacientes receberam uma dose semanal de 200 mg de sacarato de hidróxido de ferro III diluído em 250 mL de soro fisiológico a 0,9 por cento, administrado por via intravenosa em trinta minutos. O tratamento foi realizado até a obtenção do valor de hemoglobina igual ou maior que 12,0 g/dL para mulheres e 13,0 g/dL para homens, ou até a administração da dose total de ferro parenteral recomendada para cada paciente. A idade mediana dos cinqüenta pacientes estudados foi de 45 anos, variando entre 28 e 76 anos; quarenta (80,0 por cento) eram do sexo feminino. A causa mais comum de anemia ferropriva no sexo feminino foi sangramento uterino anormal observado em 25/40 pacientes (62,5 por cento) e, no sexo masculino, gastrectomia parcial em 7/10 (70,0 por cento). Vinte e quatro (48,0 por cento) pacientes foram incluídos nesse estudo por falta de resposta à terapia com ferro oral, 22 (44,0 por cento) por intolerância ao ferro oral e quatro (8,0 por cento) por hemoglobina < 7,0 g/dL. Os valores médios da hemoglobina e da ferritina sérica foram de 8,48 g/dL e 4,65 ng/mL (pré-tratamento) e 12,34 g/dL e 93,20 ng/mL (pós-tratamento)(p<0,001), respectivamente. O aumento médio de hemoglobina foi de 3,61 g/dL e de 4,83 g/dL para os sexos feminino e masculino, respectivamente. Correção da anemia foi obtida em 26 (65,0 por cento) das quarenta pacientes do sexo feminino e em nove (90,0 por cento)...

The objective of this study was to evaluate the efficacy of intravenous iron III-hydroxide saccharate to treat adult patients with iron deficiency anemia. Between January 2003 and December 2005 we studied 50 patients with iron deficiency anemia who presented intolerance or inadequate response to oral iron therapy, or hemoglobin level < 7 g/dL. The main laboratory tests performed were: complete blood cell count, reticulocyte count, serum iron, total iron-binding capacity and serum ferritin. The patients received a weekly dose of 200 mg of iron diluted in 250 mL of 0.9 percent sodium chloride solution administered intravenously during 30 minutes. It was performed until a hemoglobin level = 12.0 g/dL for women or13.0 g/dL for men was reached or completing the administration of the total dose of parenteral iron recommended for each patient. The median age of the patients studied was 45 years (age range from 18 to 76). Forty out of 25 patients (80 percent) were women. The most common cause of iron deficiency anemia was abnormal uterine bleeding observed in 62.5 percent of female patients (25 out of 40) and partial gastrectomy in 70 percent of male patients (7 out of 10). Twenty-four (48 percent) patients were included in this study due to a lack of response to oral iron therapy, 22 (44 percent) showed intolerance to oral iron and 2 (8 percent) presented with a hemoglobin level < 7.0 g/dL. The mean hemoglobin and ferritin values were 8.48 g/dL and 4.65 ng/mL (pretreatment) and 12.34 g/dL and 93.20 ng/mL (post-treatment) (p<0.001), respectively. The average increase of hemoglobin was 3.61 g/dL and 4.83 gdL for women and men, respectively. Correction of anemia was obtained in 26 out of 40 female patients (65 percent) and in 9 out of 10 male patients (90 percent). Six patients received blood transfusions before starting intravenous iron treatment. None of the 50 studied patients needed red blood cell transfusions during or after completing...