Oral iron chelators for clinical use

The Role of Magnesium in Pregnancy and in Fetal Programming of Adult Diseases

Magnesium is an essential trace metal and a necessary factor for multiple biochemical functions in humans. Its role in biology is fundamental in over 600 enzymatic reactions implicated in protein synthesis, mitochondrial functions, neuromuscular activity, bone formation, and immune system competence. Magnesium status is relevant in fetal development during gestation and in the newborn growth during the perinatal period. Moreover, magnesium is able to influence fetal programming and disease presentation in childhood or adulthood. The aim of this review is to focus on this metal homeostasis, analyzing its normal values, the causes of hypomagnesemia, the interaction with drugs and other conditions, and the diseases associated with magnesium value alteration during pregnancy, in order to study its role in fetal programming of adult diseases. The data here reported clearly indicated the existence of a connection between magnesium status and human pathology starting from intrauterine life and extending into childhood and adulthood.

Copper-Induced Epigenetic Changes Shape the Clinical Phenotype in Wilson's Disease

Wilson's disease is a congenital disorder of copper metabolism whose pathogenesis remains, at least in part, unknown. Subjects carrying the same genotype may show completely different phenotypes, differing for the age at illness onset or for the hepatic, neurologic or psychiatric clinical presentation. The inability to find a unequivocal correlation between the type of mutation in the ATPase copper transporting beta (ATP7B) gene and the phenotypic manifestation, has encouraged many authors to look for epigenetic factors interacting with the genetic changes. Here, the evidences regarding the ability of copper overload to change the global DNA methylation status are discussed.

Chelating Agents in Soil Remediation: A New Method for a Pragmatic Choice of the Right Chelator

Soil pollution by metal ions constitutes one of the most significant environmental problems in the world, being the ecosystems of extended areas wholly compromised. The remediation of soils is an impelling necessity, and different methodologies are used and studied for reaching this goal. Among them, the application of chelating agents is one of the most promising since it could allow the removal of metal ions while preserving the most meaningful properties of the original soils. The research in this field requires the joined contribute of different expertise spanning from biology to chemistry. In this work, we propose a parsimonious and pragmatic approach for screening among a range of potential chelating agents. This methodology, the Nurchi's method, is based on an extension of the Reilley procedure for EDTA titrations. This allows forecasting the binding ability of chelating agents toward the target polluting metal ions and those typically found in soils, based on the knowledge of the related protonation and complex formation constants. The method is thoroughly developed, and then tested by application to some representative cases. Its use and relevance in biomedical and industrial applications is also discussed.

New strong extrafunctionalizable tris(3,4-HP) and bis(3,4-HP) metal sequestering agents: synthesis, solution and in vivo metal chelation

Finding new multifunctional metal binders to be potentially used in diagnosis or therapy has been a subject of major challenge. Hydroxypyridinones have long been recognized as privileged chelating structures for the design of metal chelating drugs, especially towards hard metal ions, in view of their decorporation in metal overload disorders. Thus, pursuing our strategy of engineering new polydentate 3-hydroxy-4-pyridinones (3,4-HP) with extrafunctionalization capacity for sensing or targeting purposes, we report herein the synthesis and full characterization of a hexadentate (tris-3,4-HP) and a tetradentate (bis-3,4-HP) ligand, possessing three and two 3,4-HP arms N-attached to an aminomethanetrispropionic acid backbone, respectively. Thus, as compared with previously reported analogues, each ligand possesses an extra free amino group ready for further functionalization. Their chelating capacity towards Fe and Al was evaluated in aqueous solution, by potentiometric and spectroscopic techniques, and they proved to be strong sequestering agents for these metal ions without depletion of Zn, an essential biometal. Their excellent in vivo metal-decorporation capacity was also evidenced in mice injected with a radiotracer (⁶⁷Ga) as an animal model of metal overload pathological situations. These findings provide encouragement for further ongoing extrafunctionalizations in view of several potential biomedical applications.

Chemical features of in use and in progress chelators for iron overload

An excessive amount of iron may become extremely toxic both for its ability to generate reactive oxygen species, and for the lack of regulatory mechanisms for iron excretion in humans. Chelation therapy has been introduced in clinical practice in the 1970's to defend thalassemia patients from the effects of iron overload and it has dramatically changed both life expectancy and quality of life. The disadvantages of the drugs in clinical use make the research for new, more suitable iron chelating agents, urgent. This review defines the requirements of an iron chelator, then points out the principal chemical features of the iron chelators in use. Finally, a survey on the last ten years of the literature relative to iron chelators is done, and the most interesting ligands are presented, with particular emphasis to those that reached clinical trials.

RNA-Binding Efficacy of N-Phenylbenzohydroxamic Acid: An Invitro and Insilico Approach

RNA has attracted recent attention for its key role in gene expression and hence targeting by small molecules for therapeutic intervention. This study is aimed to elucidate the specificity of RNA binding affinity of parent compound of N-arylhydroxamic acids series, N-phenylbenzohydroxamic acid trivially named as PBHA,C6H5NOH.C6H5C˭O. The binding behavior was examined by various biophysical methods such as absorption, fluorescence, and viscosity measurements. Molecular docking was also done. The value of affinity constant and overall binding constant was calculated 5.79±0.03×10(4) M(-1) and K'=1.09±0.03×10(5) M(-1), respectively. The Stern-Volmer constant Ksv obtained was 2.28±0.04×10(4) M(-1). The compound (PBHA) shows a concentration-based enhancement of fluorescence intensity with increasing RNA concentration. Fluorescence quenching of PBHA-RNA complex in presence of K4 [Fe(CN)6] was also observed. Viscometric studies complimented the UV results where a continuous increase in relative viscosity of the RNA solution was observed with added optimal PBHA concentration. All the experimental evidences indicate that PBHA can strongly bind to RNA through an intercalative mode.

Iron Chelating Agents for Iron Overload Diseases

Although iron is an essential element for life, an excessive amount may become extremely toxic both for its ability to generate reactive oxygen species, and for the lack in humans of regulatory mechanisms for iron excretion. Chelation therapy has been introduced in clinical practice in the seventies of last century to defend thalassemic patients from the effects of iron overload and, in spite of all its limitations, it has dramatically changed both life expectancy and quality of life of patients. It has to be considered that the drugs in clinical use present some disadvantages too, this makes urgent new more suitable chelating agents. The requirements of an iron chelator have been better and better defined over the years and in this paper they will be discussed in detail. As a final point the most interesting ligands studied in the last years will be presented.

Anchoring group effects of surface ligands on magnetic properties of Fe₃ O₄ nanoparticles: towards high performance MRI contrast agents

The effect of the anchoring group of surface ligands on the magnetic properties, especially relaxometric properties, of PEGylated Fe₃ O₄ nanoparticles is investigated. Systematic experimental results together with in-depth theoretical analysis reveal that the ligand binding affinity can largely vary the saturation magnetization, whereas conjugated anchoring groups can remarkably enhance the transverse relaxivity, which highlights a novel approach for achieving high-performance MRI contrast agents.

Different approaches to the study of chelating agents for iron and aluminium overload pathologies

Our objective is to illustrate the activity of the groups operating in Italy involved in identification and study of new chelating agents, mainly intended for treatment of human pathology correlated with metal overload. The objective of "chelation therapy" is removal of toxic metal ions from the human body or attenuation of their toxicity by transforming them into less toxic compounds or by dislocating them from the site at which they exert a toxic action. Because most of this research activity is related to chelating agents for iron and aluminium, diseases related to these two metal ions are briefly treated. Iron overload is the most common metal toxicity disease worldwide. The toxicity of aluminium in dialysis patients was a serious problem for haemodialysis units in the seventies and eighties of the last century. In particular, this review focuses on research performed by the group at Cagliari and Ferrara, and by that at Padova. The former is studying, above all, bisphosphonate and kojic acid derivatives, and the latter is investigating 3,4-hydroxypyridinecarboxylic acids with differently substituted pyridinic rings.

New asymmetric heptaaza Schiff base macrocyclic complex of Mn(II): Crystal structure, biological and DFT studies

A new asymmetric heptaaza Schiff base macrocyclic bis(pendant donor) manganese(II) complex, [MnL(1)](ClO(4))(2).CH(3)CN (1), has been prepared and characterized by X-ray diffraction and spectroscopic methods. The antimicrobial activity of 1 and a series of its familiar symmetric heptaaza [15]pydieneN(5), [16]pydieneN(5), and [17]pydieneN(5)-based bis-(2-aminoethyl) pendant armed Schiff base macrocyclic complexes of Mn(II) were tested against Escherichia coli, Staphylococcus aureus and Candida albicans. The results showed that the symmetric heptaaza [16]pydieneN(5), and [17]pydieneN(5)-based Schiff base macrocyclic complexes of Mn(II) had remarkable inhibition zone on the culture of S. aureus and E. coli as compared with standard drugs. The optimized geometry of the prepared complex has been obtained from density functional method, DFT, using B3LYP/6-31G* basis set.

Potentiometric, spectrophotometric and calorimetric study on iron(III) and copper(II) complexes with 1,2-dimethyl-3-hydroxy-4-pyridinone

The iron(III)-1,2-dimethyl-3-hydroxy-4-pyridinone (Deferiprone) system is carefully characterized by a combined potentiometric-spectrophotometric procedure at 25 and 37 degrees C at different ionic strengths, and by thermochemical and quantum-chemical studies. The main purpose of this work was to determine how the temperature dependence of both complex-formation and protonation constants can affect the pFe values on going from 25 degrees C (pFe is normally calculated using 25 degrees C stability constants) to the physiological temperature of 37 degrees C at which chelating agents are active in vivo. The copper(II)-Deferiprone system is also studied and the iron(III)-Deferiprone distribution diagrams in presence of variable copper(II) amounts are shown so as to explain possible side effects due to a competing metal ion during the chelating therapy of iron overload.

Potentiometric and spectrophotometric equilibrium study on Fe(III) and new catechol-bisphosphonate conjugates

The coordination properties of mixed catechol-bisphosphonates towards Fe(III) are presented. From the potentiometric and spectroscopic results it was possible to state that iron coordination takes place only on the bisphosphonate moiety at acidic pH, and involves both catechol and bisphosphonate groups on two different iron(III) ions at higher pH values. Steric constracts keep both groups from chelating the same metal ion. Quantum mechanical calculations confirm this statement and allow to determine the minimum length of the linker for a stable conformation of complexes in which the same iron(III) ion is coordinated by both catechol and bisphosphonate.