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The novel ligand (H 2 L), N’-(2-cyanoacetyl)isonicotinohydrazide, has been synthesized via reacting the isonicotinic hydrazide with 1-cyanoacetyl-3,5-dimethylpyrazole. The keto-form of the free ligand has been evoked from its spectral data. Based on elemental analyses and mass spectra, the ligand formed 1:1 (M: L) metal complexes with the acetate salts of Cu(II), Co(II), Ni(II) and Zn(II). The complexes’ spectral analyses revealed that the ligand behaved as a mononegative bidentate via the hydrazonyl N 1 and deprotonated enolized acetyl oxygen. Moreover, the DFT quantum chemical calculations revealed that the ligand had higher HOMO and lower LUMO energies than metal complexes, implying an electron donating character. Furthermore, the in vitro anticancer activity against HepG2 and HCT-116 cell lines displayed that the ligand was more potent than doxorubicin against both cell lines, although the metal complexes displayed lower efficacy.

This chapter contains sections titled: Introduction Imine/Aminol‐Based Chemosensor Chemosensors Based on Reactions between Aldehydes and Alcohols or Other Nucleophiles Reagents Based on Irreversible Covalent Interactions Chemosensors Based on the Michael Addition Reaction Chemosensors Based on Metal‐Anion/Ligand Interactions References

Patients suffering from iron overload can experience serious complications. In such patients, various organs, such as endocrine glands and liver, can be damaged. Although iron is a crucial element for life, iron overload can be potentially toxic for human cells due to its role in generating free radicals. In the past few decades, there has been a major improvement in the survival of patients who suffer from iron overload due to the application of iron chelation therapy in clinical practice. In clinical use, deferoxamine, deferiprone, and deferasirox are the three United States Food and Drug Administration-approved iron chelators. Each of these iron chelators is well known for the treatment of iron overload in various clinical conditions. Based on several up-to-date studies, this study explained iron overload and its clinical symptoms, introduced each of the above-mentioned iron chelators, and evaluated their advantages and disadvantages with an emphasis on combination therapy, which in recent studies seems a promising approach. In numerous clinical conditions, due to the lack of accurate indicators, choosing a standard approach for iron chelation therapy can be difficult; therefore, further studies on the issue are still required. This study aimed to introduce each of these iron chelators, combination therapy, usage doses, specific clinical applications, and their advantages, toxicity, and side effects.

Inherited haemoglobin disorders, including thalassaemia and sickle-cell disease, are the most common monogenic diseases worldwide. Several clinical forms of α-thalassaemia and β-thalassaemia, including the co-inheritance of β-thalassaemia with haemoglobin E resulting in haemoglobin E/β-thalassaemia, have been described. The disease hallmarks include imbalance in the α/β-globin chain ratio, ineffective erythropoiesis, chronic haemolytic anaemia, compensatory haemopoietic expansion, hypercoagulability, and increased intestinal iron absorption. The complications of iron overload, arising from transfusions that represent the basis of disease management in most patients with severe thalassaemia, might further complicate the clinical phenotype. These pathophysiological mechanisms lead to an array of clinical manifestations involving numerous organ systems. Conventional management primarily relies on transfusion and iron-chelation therapy, as well as splenectomy in specific cases. An increased understanding of the molecular and pathogenic factors that govern the disease process have suggested routes for the development of new therapeutic approaches that address the underlying chain imbalance, ineffective erythropoiesis, and iron dysregulation, with several agents being evaluated in preclinical models and clinical trials.

Deferoxamine B is an outstanding molecule which has been widely studied in the past decade for its ability to bind iron and many other metal ions. The versatility of this metal chelator makes it suitable for a number of medicinal and analytical applications, from the well-known iron chelation therapy to the most recent use in sensor devices. The three bidentate hydroxamic functional groups of deferoxamine B are the centerpiece of its metal binding ability, which allows the formation of stable complexes with many transition, lanthanoid and actinoid metal ions. In addition to the ferric ion, in fact, more than 20 different metal complexes of deferoxamine b have been characterized in terms of their chemical speciation in solution. In addition, the availability of a terminal amino group, most often not involved in complexation, opens the way to deferoxamine B modification and functionalization. This review aims to collect and summarize the available data concerning the complex-formation equilibria in solutions of deferoxamine B with different metal ions. A general overview of the progress of its applications over the past decade is also discussed, including the treatment of iron overload-associated diseases, its clinical use against cancer and neurodegenerative disorders and its role as a diagnostic tool.

Four novel ligand-metal complexes were synthesized through the reaction of Fe(III), pleaseCo(II), Zn(II), and Zr(IV) with Schiff base gemifloxacin reacted with ortho-phenylenediamine (GMFX-o-phdn) to investigate their biological activities. Elemental analysis, FT-IR, 1H NMR, UV-visible, molar conductance, melting points, magnetic susceptibility, and thermal analyses have been carried out for insuring the chelation process. The antimicrobial activity was carried out against Monilinia fructicola, Aspergillus flavus, Penicillium italicum, Botrytis cinerea, Escherichia coli, Bacillus cereus, Pseudomonas fluorescens, and P. aeruginosa. The radical scavenging activity (RSA%) was in vitro evaluated using ABTS method. FT-IR spectra indicated that GMFX-o-phdn chelated with metal ions as a tetradentate through oxygen of carboxylate group and nitrogen of azomethine group. The data of infrared, 1H NMR, and molar conductivity indicate that GMFX–o-phdn reacted as neutral tetra dentate ligand (N2O2) with metal ions through the two oxygen atoms of the carboxylic group (oxygen containing negative charge) and two nitrogen atoms of azomethine group (each nitrogen containing a lone pair of electrons) (the absent of peak corresponding to ν(COOH) at 1715 cm−1, the shift of azomethine group peak from 1633 cm−1 to around 1570 cm−1, the signal at 11 ppm of COOH and the presence of the chloride ions outside the complex sphere). Thermal analyses (TG-DTG/DTA) exhibited that the decaying of the metal complexes exists in three steps with the final residue metal oxide. The obtained data from DTA curves reflect that the degradation processes were exothermic or endothermic. Results showed that some of the studied complexes exhibited promising antifungal activity against most of the tested fungal pathogens, whereas they showed higher antibacterial activity against E. coli and B. cereus and low activity against P. fluorescens and P. aeruginosa. In addition, GMFX-o-phdn and its metal complexes showed strong antioxidant effect. In particular, the parent ligand and Fe(III) complex showed greater antioxidant capacity at low tested concentrations than that of other metal complexes where their IC50 were 169.7 and 164.6 µg/mL, respectively.

Precious metal complexes with the d6 valence electron configuration often exhibit luminescent metal-to-ligand charge transfer (MLCT) excited states, which form the basis for many applications in lighting, sensing, solar cells and synthetic photochemistry. Iron(ii) has received much attention as a possible Earth-abundant alternative, but to date no iron(ii) complex has been reported to show MLCT emission upon continuous-wave excitation. Manganese(i) has the same electron configuration as that of iron(ii), but until now has typically been overlooked in the search for cheap MLCT luminophores. Here we report that isocyanide chelate ligands give access to air-stable manganese(i) complexes that exhibit MLCT luminescence in solution at room temperature. These compounds were successfully used as photosensitizers for energy- and electron-transfer reactions and were shown to promote the photoisomerization of trans-stilbene. The observable electron transfer photoreactivity occurred from the emissive MLCT state, whereas the triplet energy transfer photoreactivity originated from a ligand-centred 3π–π* state.Manganese(i) is isoelectronic to iron(ii) but has typically been overlooked as a cheap Earth-abundant metal for the development of 3d6 metal-to-ligand charge transfer (MLCT) emitters and photosensitizers. Now, using chelating isocyanide ligands, air-stable manganese(i) complexes have been obtained that exhibit MLCT luminescence, as well as energy- and electron-transfer photoreactivity.

Many microbial enzymes are metal-dependent, and the microbe must acquire scarce metals from the environment. Microbes that use methane as a carbon source have a copper-dependent enzyme that oxidizes the methane. Peptides known as methanobactins (Mbns) acquire copper by using a pair of ligands comprising a nitrogen-containing ring and an adjacent thioamide. Kenney et al. describe the biosynthetic machinery that adds the copper-binding groups to a precursor peptide. This involves a complex of two homologs: MbnB, a member of a functionally uncharacterized protein family that includes a diiron cluster, and MbnC, which is even less well characterized. The iron cofactor is required for ligand synthesis. MbnB and MbnC homologs are encoded in many genomes, suggesting that they may have roles beyond Mbn biosynthesis. Science , this issue p. 1411 An enzyme complex uses iron and dioxygen to generate copper-binding ligands in the methanobactin family of natural products. Metal homeostasis poses a major challenge to microbes, which must acquire scarce elements for core metabolic processes. Methanobactin, an extensively modified copper-chelating peptide, was one of the earliest natural products shown to enable microbial acquisition of a metal other than iron. We describe the core biosynthetic machinery responsible for the characteristic posttranslational modifications that grant methanobactin its specificity and affinity for copper. A heterodimer comprising MbnB, a DUF692 family iron enzyme, and MbnC, a protein from a previously unknown family, performs a dioxygen-dependent four-electron oxidation of the precursor peptide (MbnA) to install an oxazolone and an adjacent thioamide, the characteristic methanobactin bidentate copper ligands. MbnB and MbnC homologs are encoded together and separately in many bacterial genomes, suggesting functions beyond their roles in methanobactin biosynthesis.

Background Despite significant therapeutic advancements in recent decades, colorectal cancer (CRC) continues to exhibit high rates of mortality and morbidity. Chemoresistance and cancer recurrence remain substantial challenges, underscoring the need for novel treatment approaches. Iron chelation therapy has gained profound interest over the years as a potential cancer treatment, leveraging the increased iron demand by tumors. This review evaluates the effects of iron chelation therapy on CRC progression and the underlying mechanisms. Method A comprehensive review of in vivo and in vitro studies was conducted to assess the effectiveness of iron chelation therapy in CRC. The literature search covered PubMed, Scopus, Medline (via Web of Science), and EMBASE between January 1995 and March 2024. Results Several in vitro and in vivo studies have investigated the impact of iron chelators, such as deferoxamine, deferasirox, thiosemicarbazone‐based chelators, quilamine‐based chelators, and other novel compounds on CRC. Natural plant extracts with iron‐chelating properties have also been explored as potential treatments. Most studies indicate that iron chelation can inhibit the proliferation of colon cancer cells, though some studies suggest cancer‐promoting effects. Mechanistically, iron chelation affects several hallmarks of CRC by modulating histone methylation, upregulating NDRG1, and influencing the Wnt/β‐catenin and p53 signaling pathways. However, certain iron chelators may inhibit TRAIL‐mediated apoptosis and activate the hypoxia‐inducible factor (HIF), potentially accelerating CRC progression. Conclusion Future exploration of iron chelation therapy in CRC should focus on extensive in vitro, in vivo, and clinical studies to elucidate the precise mechanisms involved. A deeper understanding of the genetic and cellular alterations induced by iron chelation will enhance the development of effective therapeutic strategies for CRC. Iron chelation is a promising yet underexplored strategy for colorectal cancer (CRC) treatment. Iron chelators have a dual role in inhibiting and potentially promoting cancer progression. Iron chelation affects key CRC pathways, including histone methylation, NDRG1 upregulation, Wnt/β‐catenin, and p53 modulation. Comprehensive in vitro and in vivo analyses reveal the need for additional studies to fully understand the antiproliferative mechanisms and cellular targets of iron chelators.

Heavy metals are essential for a wide range of biological processes, including the growth and reproduction of cells, synthesis of biomolecules, many enzymatic reactions, and the body’s immunity, but their excessive intake is harmful. Specifically, they cause oxidative stress (OS) and generate free radicals and reactive oxygen species (ROS) in metabolism. In addition, the accumulation of heavy metals in humans can cause serious damage to different organs, especially respiratory, nervous and reproductive and digestive systems. Biologically, metal chelation therapy is often used to treat metal toxicity. This process occurs through the interaction between the ligand and a central metal atom, forming a complex ring-like structure. After metals are chelated with appropriate chelating agents, their damage in metabolism can be prevented and efficiently removed from the body. On the other hand, heavy metals, including Zn, Fe and Cu, are necessary for the suitable functioning of different proteins including enzymes in metabolism. However, when the same metals accumulate at levels higher than the optimum level, they can easily become toxic and have harmful effects toward biomolecules. In this case, it induces the formation of ROS and nitrogen species (RNS) resulting in peroxidation of biological molecules such as lipids in the plasma membrane. Antioxidants have an increasing interest in many fields due to their protective effects, especially in food and pharmaceutical products. Screening of antioxidant properties of compounds needs appropriate methods including metal chelating assay. In this study, a general approach to the bonding and chelating properties of metals is described. For this purpose, the basic principles and chemical principles of metal chelation methods, both in vivo and in vitro, are outlined and discussed. Hence, in the main sections of this review, the descriptions related to metal ions, metal chelating, antioxidants, importance of metal chelating in biological system and definitions of metal chelating assays as widely used methods to determine antioxidant ability of compounds are provided. In addition, some chemical properties, technical and critical details of the used chelation methods are given.