A Crucial Role of Proteolysis in the Formation of Intracellular Dinitrosyl Iron Complexes.

Dinitrosyl iron complexes (DNICs) stabilize nitric oxide in cells and tissues and constitute an important form of its storage and transportation. DNICs may comprise low-molecular-weight ligands, e.g., thiols, imidazole groups in chemical compounds with low molecular weight (LMWDNICs), or high-molecular-weight ligands, e.g., peptides or proteins (HMWDNICs). The aim of this study was to investigate the role of low- and high-molecular-weight ligands in DNIC formation. Lysosomal and proteasomal proteolysis was inhibited by specific inhibitors. Experiments were conducted on human erythroid K562 cells and on K562 cells overexpressing a heavy chain of ferritin. Cell cultures were treated with •NO donor. DNIC formation was monitored by electron paramagnetic resonance. Pretreatment of cells with proteolysis inhibitors diminished the intensity and changed the shape of the DNIC-specific EPR signal in a treatment time-dependent manner. The level of DNIC formation was significantly influenced by the presence of protein degradation products. Interestingly, formation of HMWDNICs depended on the availability of LMWDNICs. The extent of glutathione involvement in the in vivo formation of DNICs is minor yet noticeable, aligning with our prior research findings.

Radiation and Radical Grafting Compatibilization of Polymers for Improved Bituminous Binders-A Review.

This review scrutinizes current research on new methods for enhancing bituminous binder performance through radiation and radical grafting of polymer modifiers of bitumen. It investigates innovative methods, including using waste polymers as modifiers and applying radiation for polymer grafting, to overcome challenges like high costs, low aging resistance, and storage stability issues, of which separation of phases polymer/bitumen is the most significant obstacle. These advanced modification techniques promise sustainability through the decrease of the carbon footprint of transportation systems by improving the properties and durability of binders. Additionally, this review discusses the parameters and mechanistic aspects from a scientific perspective, shedding light on the underlying processes that contribute to the improved performance of modified bituminous binders.

Fe(III) and Cu(II) Complexes of Chlorogenic Acid: Spectroscopic, Thermal, Anti-/Pro-Oxidant, and Cytotoxic Studies.

Complexes of chlorogenic acid (5-CQA) with copper(II) and iron(III) were synthesized in a solid state and examined by means of FT-IR, thermogravimetric, and elemental analyses. The molar stoichiometric ratios of metal:ligand for the solid forms of the complexes were established as Cu(II):L = 1:2 and Fe(III):L = 2:3 (L: 5-CQA), with the possible coordination through the carboxylate group and the hydroxyl group from the catechol moiety. In an aqueous solution at pH = 7.4, the composition of the complexes was Cu(II):L = 1:1, and Fe(III):L = 1:1 and 1:2. The Cu(II) and Fe(III) complexes with 5-CQA showed lower antioxidant properties, as estimated by the spectrophotometric methods with DPPH•, ABTS•+, and HO• radicals, than the ligand alone, whereas in the lipid peroxidation inhibition assay, the metal complexes revealed a higher antioxidant activity than 5-CQA. Cu(II) 5-CQA showed the highest pro-oxidant activity in the Trolox oxidation assays compared to the other studied compounds. The lipophilic parameters of the compounds were estimated using the HPLC method. 5-CQA and its complexes with Fe(III) and Cu(II) were not toxic to HaCaT cells in a tested concentration range of 0.15-1000 nM after a 24 h incubation time.

Radical Composition and Radical Reaction Kinetics in the Probe-Irradiated XLPE Samples as a Potential Source of Information on Their Aging Degree.

Polyethylene is a model polyolefin, and a widely used material for the manufacture of many products, including cable sheaths. Understanding degradation mechanisms at the atomic scale leading to oxidation during aging is crucial for many long-term applications. The concentrations of radicals derived from oxidation and chain scission during radio-oxidation, as well as their ratio, are important parameters controlling the predominance of chain scission or crosslinking of the polymer. In this work, we propose a cryogenic EPR technique for measuring oxidation- and fragmentation-derived radicals as a less-destructive method for the evaluation of cable insulation aging and performance capability. We investigate the effect of the low-dose and high-dose radiation aging on the formation of free radicals in the polymer matrix that are both unprotected and protected by antioxidants. The stability of radicals after aging is a determinant of macroscopic processes and structural changes during aging. Under the conditions of the higher dose rate, the peroxy radical buildup is lower per dose. Peroxy radical buildup is followed by decay during aging, in accordance with POOH content. Our results allow the prediction of the capability of the antioxidant to protect the XLPE material in the function of dose and time.

Abdominoplasty Skin-Based Dressing for Deep Wound Treatment-Evaluation of Different Methods of Preparation on Therapeutic Potential.

The management of hard-to-heal wounds is a significant clinical challenge. Acellular dermal matrices (ADMs) have been successfully introduced to enhance the healing process. Here, we aimed to develop protocol for the preparation of novel ADMs from abdominoplasty skin. We used three different decellularization protocols for skin processing, namely, 1M NaCl and sodium dodecyl sulfate (SDS, in ADM1); 2M NaCl and sodium dodecyl sulfate (SDS, in ADM1); and a combination of recombinant trypsin and Triton X-100 (in hADM 3). We assessed the effectiveness of decellularization and ADM's structure by using histochemical and immunochemical staining. In addition, we evaluated the therapeutic potential of novel ADMs in a murine model of wound healing. Furthermore, targeted transcriptomic profiling of genes associated with wound healing was performed. First, we found that all three proposed methods of decellularization effectively removed cellular components from abdominoplasty skin. We showed, however, significant differences in the presence of class I human leukocyte antigen (HLA class I ABC), Talin 1/2, and chondroitin sulfate proteoglycan (NG2). In addition, we found that protocols, when utilized differentially, influenced the preservation of types I, III, IV, and VII collagens. Finally, we showed that abdominoplasty skin-derived ADMs might serve as an effective and safe option for deep wound treatment. More importantly, our novel dressing (ADM1) improves the kinetics of wound closure and scar maturation in the proliferative and remodeling phases of wound healing. In conclusion, we developed a protocol for abdominoplasty skin decellularization suitable for the preparation of biological dressings. We showed that different decellularization methods affect the purity, structure, and therapeutic properties of ADMs.

Plant-Derived and Dietary Hydroxybenzoic Acids-A Comprehensive Study of Structural, Anti-/Pro-Oxidant, Lipophilic, Antimicrobial, and Cytotoxic Activity in MDA-MB-231 and MCF-7 Cell Lines.

Seven derivatives of plant-derived hydroxybenzoic acid (HBA)-including 2,3-dihydroxybenzoic (2,3-DHB, pyrocatechuic), 2,4-dihydroxybenzoic (2,4-DHB, ß-resorcylic), 2,5-dihydroxybenzoic (2,5-DHB, gentisic), 2,6-dihydroxybenzoic (2,6-DHB, γ-resorcylic acid), 3,4-dihydroxybenzoic (3,4-DHB, protocatechuic), 3,5-dihydroxybenzoic (3,5-DHB, α-resorcylic), and 3,4,5-trihydroxybenzoic (3,4,5-THB, gallic) acids-were studied for their structural and biological properties. Anti-/pro-oxidant properties were evaluated by using DPPH• (2,2-diphenyl-1-picrylhydrazyl), ABTS•+ (2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), FRAP (ferric-reducing antioxidant power), CUPRAC (cupric-reducing antioxidant power), and Trolox oxidation assays. Lipophilicity was estimated by means of experimental (HPLC) and theoretical methods. The antimicrobial activity against Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa), Staphylococcus aureus (S. aureus), Bacillus subtilis (B. subtilis), Salmonella enteritidis (S. enteritidis), and Candida albicans (C. albicans) was studied. The cytotoxicity of HBAs in MCF-7 and MDA-MB-231 cell lines was estimated. Moreover, the structure of HBAs was studied by means of experimental (FTIR, 1H, and 13C NMR) and quantum chemical DFT methods (the NBO and CHelpG charges, electrostatic potential maps, and electronic parameters based on the energy of HOMO and LUMO orbitals). The aromaticity of HBA was studied based on the calculated geometric and magnetic aromaticity indices (HOMA, Aj, BAC, I6, NICS). The biological activity of hydroxybenzoic acids was discussed in relation to their geometry, the electronic charge distribution in their molecules, their lipophilicity, and their acidity. Principal component analysis (PCA) was used in the statistical analysis of the obtained data and the discussion of the dependency between the structure and activity (SAR: structure-activity relationship) of HBAs. This work provides valuable information on the potential application of hydroxybenzoic acids as bioactive components in dietary supplements, functional foods, or even drugs.

Optimization of Novel Human Acellular Dermal Dressing Sterilization for Routine Use in Clinical Practice.

Gamma rays and electrons with kinetic energy up to 10 MeV are routinely used to sterilize biomaterials. To date, the effects of irradiation upon human acellular dermal matrices (hADMs) remain to be fully elucidated. The optimal irradiation dosage remains a critical parameter affecting the final product structure and, by extension, its therapeutic potential. ADM slides were prepared by various digestion methods. The influence of various doses of radiation sterilization using a high-energy electron beam on the structure of collagen, the formation of free radicals and immune responses to non-irradiated (native) and irradiated hADM was investigated. The study of the structure changes was carried out using the following methods: immunohistology, immunoblotting, and electron paramagnetic resonance (EPR) spectroscopy. It was shown that radiation sterilization did not change the architecture and three-dimensional structure of hADM; however, it significantly influenced the degradation of collagen fibers and induced the production of free radicals in a dose-dependent manner. More importantly, the observed effects did not disrupt the therapeutic potential of the new transplants. Therefore, radiation sterilization at a dose of 35kGy can ensure high sterility of the dressing while maintaining its therapeutic potential.

Crystal Structure, Spectroscopic Characterization, Antioxidant and Cytotoxic Activity of New Mg(II) and Mn(II)/Na(I) Complexes of Isoferulic Acid.

The Mg(II) and heterometallic Mn(II)/Na(I) complexes of isoferulic acid (3-hydroxy-4-methoxycinnamic acid, IFA) were synthesized and characterized by infrared spectroscopy FT-IR, FT-Raman, electronic absorption spectroscopy UV/VIS, and single-crystal X-ray diffraction. The reaction of MgCl2 with isoferulic acid in the aqueous solutions of NaOH resulted in synthesis of the complex salt of the general formula of [Mg(H2O)6]⋅(C10H9O4)2⋅6H2O. The crystal structure of this compound consists of discrete octahedral [Mg(H2O)6]2+ cations, isoferulic acid anions and solvent water molecules. The hydrated metal cations are arranged among the organic layers. The multiple hydrogen-bonding interactions established between the coordinated and lattice water molecules and the functional groups of the ligand stabilize the 3D architecture of the crystal. The use of MnCl2 instead of MgCl2 led to the formation of the Mn(II)/Na(I) complex of the general formula [Mn3Na2(C10H7O4)8(H2O)8]. The compound is a 3D coordination polymer composed of centrosymmetric pentanuclear subunits. The antioxidant activity of these compounds was evaluated by assays based on different antioxidant mechanisms of action, i.e., with •OH, DPPH• and ABTS•+ radicals as well as CUPRAC (cupric ions reducing power) and lipid peroxidation inhibition assays. The pro-oxidant property of compounds was measured as the rate of oxidation of Trolox. The Mg(II) and Mn(II)/Na(I) complexes with isoferulic acid showed higher antioxidant activity than ligand alone in DPPH (IFA, IC50 = 365.27 µM, Mg(II) IFA IC50 = 153.50 µM, Mn(II)/Na(I) IFA IC50 = 149.00 µM) and CUPRAC assays (IFA 40.92 µM of Trolox, Mg(II) IFA 87.93 µM and Mn(II)/Na(I) IFA 105.85 µM of Trolox; for compounds' concentration 10 µM). Mg(II) IFA is a better scavenger of •OH than IFA and Mn(II)/Na(I) IFA complex. There was no distinct difference in ABTS•+ and lipid peroxidation assays between isoferulic acid and its Mg(II) complex, while Mn(II)/Na(I) complex showed lower activity than these compounds. The tested complexes displayed only slight antiproliferative activity tested in HaCaT human immortalized keratinocyte cell line within the solubility range. The Mn(II)/Na(I) IFA (16 µM in medium) caused an 87% (±5%) decrease in cell viability, the Mg salt caused a comparable, i.e., 87% (±4%) viability decrease in a concentration of 45 µM, while IFA caused this level of cell activity attenuation (87% ± 5%) at the concentration of 1582 µM (significant at α = 0.05).

The effect of ethanolic extract of Brazilian green propolis and artepillin C on aFGF-1, Eselectin, and CD40L secreted by human gingival fibroblasts.

INTRODUCTION: Periodontal diseases are among the most common diseases of the oral cavity in the worldwide population. The prevention of gingivitis and periodontitis is based on the removal of bacterial plaque from the teeth with use of toothpaste containing active substances. Noteworthy is the ethanolic extract of Brazilian green propolis (EEP-B), which, due to the high content of artepillin C, has anti-inflammatory, antibacterial, or immunostimulatory effects. Little is known about interactions between EEP-B and gingival fibroblasts within the oral cavity. The purpose of the article is to determine the role of acidic fibroblast growth factor (aFGF-1), E-selectin, and ligand of CD40 (CD40L) secreted by human gingival fibroblasts (HGF-1) in the gingiva. MATERIAL AND METHODS: We performed our experiments on gingival fibroblasts (HGF-1), which are an ideal in vitro model for studying the processes taking place within the gingiva. We incubated cells with EEP-B or artepillin C at the concentrations of 1 µg/ml and 10 µg/ml. The aFGF-1, E-selectin, and CD40L were detected using the Bio-Plex Magnetic Luminex Assay and the Bio-Plex 200 System. RESULTS: Ethanolic extract of Brazilian green propolis and artepillin C increased the levels of aFGF-1 secreted by HGF-1. Moreover, EEP-B decreased the levels of E-selectin in both tested concentrations, which was not proved for artepillin C. No changes in the concentration of CD40L released by HGF-1 were observed. CONCLUSIONS: The obtained results may suggest that EEP-B, due to the mixture of various compounds including flavonoids, accelerates the wound healing effects and has anti-inflammatory activity.

New Polyphenol-Containing LDL Nano-Preparations in Oxidative Stress and DNA Damage: A Potential Route for Cell-Targeted PP Delivery.

Low-density lipoprotein (LDL) preparations of the chosen polyphenols (PPs) were prepared for the first time in the literature. The solubility of the PPs in the lipidic core of the LDL increased with the increase of their lipophilicity. The anti-/pro-oxidative properties and toxicity of LDL-entrapped PPs toward A 2780 human ovarian cancer cells were examined. The obtained preparations were found to be stable in PBS, and characterized by low toxicity. A binding affinity study revealed that the uptake of PP-loaded LDL particles is non-receptor-specific under experimental conditions. The antioxidative potential of the obtained PPs-doped LDL preparations was shown to be higher than for the PPs themselves, probably due to facilitating transport of LDL preparations into the cellular milieu, where they can interact with the cellular systems and change the redox status of the cell. The PPs-loaded LDL displayed the highest protective effect against Fenton-type reaction induced oxidative DNA damage.

Correlations between molecular structure and biological activity in "logical series" of dietary chromone derivatives.

The research was conducted in the "logical series" of seven ligands: chromone, flavone, 3-hydroxyflavone, 3,7-dihydroxyflavone, galangin, kaempferol and quercetin. Each subsequent ligand differs from the previous one, among others by an additional hydroxyl group. The studied chromone derivatives are plant secondary metabolites which play an important role in growth, reproduction, and resistance to pathogens. They are important food ingredients with valuable pro-health properties. The studies of the relationships between their molecular structure and biological activity facilitate searching for new chemical compounds with important biological properties not by trial and error, but concerning the impact of specific changes in their structure on the compound properties. Therefore several pectroscopic methods (FT-IR, FT-Raman, 1H and 13C NMR) were applied to study the molecular structure of the compounds in the series. Moreover the quantum-chemical calculations at B3LYP/6-311++G** were performed to obtained the theoretical NMR spectra, NBO atomic charge, global reactivity descriptors and thermodynamic parameters. The antioxidant activity of the compounds was tested in the DPPH and FRAP assays and the mechanism of antioxidant activity was discussed based on the results on theoretical calculations. The cytotoxicity of the ligands toward human epithelial colorectal adenocarcinoma Caco2 cells was estimated and correlated with the lipophilicity of the compounds. The principal component analyses (PCA) and hierarchical cluster analysis were used to study the dependency between the molecular structure of ligands and their biological activity. The experimental data were related to the theoretical ones. The found regular changes in physicochemical properties correlated well with the systematic changes in antioxidant and biological properties.

LDL dinitrosyl iron complex acts as an iron donor in mouse macrophages.

[Fe(NO)2] - modified nanoparticles of low-density protein (DNICLDL) can serve as conveyors of iron in the form of stable complexes with ApoB100 protein. As reported recently, in human hepatoma cells DNICLDL significantly increased the total iron content, while showing low toxicity. In the present work, we focused on the effects of internalization of DNIC-modified lipoproteins in macrophages, with special regards to cytotoxicity. DNICLDL was administered to a model macrophage cell line, RAW 264.7. Administration of DNICLDL considerably increased total iron content. High increase of iron was accompanied by moderate toxicity. As shown by in vitro plasmid nicking assay, chelation of iron in the form of DNIC strongly reduced the iron-related reactive oxygen species (ROS) -induced DNA damage. In addition, DNICLDL, plausibly due to its NO-donating activity, did not induce inducible nitric oxide synthase (iNOS) expression, as opposed to other forms of low-density protein (LDL).

LDL dinitrosyl iron complex: A new transferrin-independent route for iron delivery in hepatocytes.

In view of the interrelations between NO, Fe, and LDL in the cardiovascular system it appears interesting to find out, if the lipoprotein particles undergo the process of iron-nitrosylation, commonly observed for other proteins and what is the biological fate of iron-nitrosylated LDL particles. Iron-nitrosylated LDL preparation containing Fe(NO)2 motif (DNICLDL) was obtained and characterized for the first time. In order to test its interactions with potential target cells, DNICLDL was administered to the hepatoma HepG2 cells. The effects were referred to those induced by native LDL (nLDL) and oxidized LDL (oxLDL) particles. DNICLDL administration considerably increased total iron content in the studied cell line, but did not influence the level of calcein-chelatable ions. DNICLDL was found to be low toxic to cells. The study suggests that DNICLDL might be a potential transducer of iron. © 2017 BioFactors, 44(2):192-201, 2018.

The role of natural polyphenols in cell signaling and cytoprotection against cancer development.

The cytoprotective and anticancer action of dietary in-taken natural polyphenols has for long been attributed only to their direct radical scavenging activities. Currently it is well supported that those compounds display a broad spectrum of biological and pharmacological outcomes mediated by their complex metabolism, interaction with gut microbiota as well as direct interactions of their metabolites with key cellular signaling proteins. The beneficial effects of natural polyphenols and their synthetic derivatives are extensively studied in context of cancer prophylaxis and therapy. Herein we focus on cell signaling to explain the beneficial role of polyphenols at the three stages of cancer development: we review the recent proceedings about the impact of polyphenols on the cytoprotective antioxidant response and their proapoptotic action at the premalignant stage, and finally we present data showing how phenolic acids (e.g., caffeic, chlorogenic acids) and flavonols (e.g., quercetin) hamper the development of metastatic cancer.

Formation of glutathionyl dinitrosyl iron complexes protects against iron genotoxicity.

Dinitrosyl iron(i) complexes (DNICs), intracellular NO donors, are important factors in nitric oxide-dependent regulation of cellular metabolism and signal transduction. It has been shown that NO diminishes the toxicity of iron ions and vice versa. To gain insight into the possible role of DNIC in this phenomenon, we examined the effect of GS-DNIC formation on the ability of iron ions to mediate DNA damage, by treatment of the pUC19 plasmid with physiologically relevant concentrations of GS-DNIC. It was shown that GS-DNIC formation protects against the genotoxic effect of iron ions alone and iron ions in the presence of a naturally abundant antioxidant, GSH. This sheds new light on the iron-related protective effect of NO under the circumstances of oxidative stress.

Spectroscopic (FT-IR, FT-Raman, 1H- and 13C-NMR), theoretical and microbiological study of trans o-coumaric acid and alkali metal o-coumarates.

This work is a continuation of research on a correlation between the molecular structure and electronic charge distribution of phenolic compounds and their biological activity. The influence of lithium, sodium, potassium, rubidium and cesium cations on the electronic system of trans o-coumaric (2-hydroxy-cinnamic) acid was studied. We investigated the relationship between the molecular structure of the tested compounds and their antimicrobial activity. Complementary molecular spectroscopic techniques such as infrared (FT-IR), Raman (FT-Raman), ultraviolet-visible (UV-VIS) and nuclear magnetic resonance (1H- and 13C-NMR) were applied. Structures of the molecules were optimized and their structural characteristics were calculated by the density functional theory (DFT) using the B3LYP method with 6-311++G** as a basis set. Geometric and magnetic aromaticity indices, atomic charges, dipole moments and energies were also calculated. Theoretical parameters were compared to the experimental characteristics of investigated compounds. Correlations between certain vibrational bands and some metal parameters, such as electronegativity, ionization energy, atomic and ionic radius, were found. The microbial activity of studied compounds was tested against Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa, Staphylococcus aureus, Proteus vulgaris and Candida albicans.

Coordination of iron ions in the form of histidinyl dinitrosyl complexes does not prevent their genotoxicity.

Formation of dinitrosyl iron complexes (DNICs) was observed in a wide spectrum of pathophysiological conditions associated with overproduction of NO. To gain insight into the possible genotoxic effects of DNIC, we examined the interaction of histidinyl dinitrosyl iron complexes (HIS-DNIC) with DNA by means of circular dichroism. Formation of DNIC was monitored by EPR and FT/IR spectroscopy. Vibrational bands for aquated HIS-DNIC are reported. Dichroism results indicate that HIS-DNIC changes the conformation of the DNA in a dose-dependent manner in 10mM phosphate buffer (pH 6). Increase of the buffer pH or ionic strength decreased the effect. Comparison of HIS-DNIC DNA interaction with the effect of hydrated Fe(2+) ion revealed many similarities. The importance of iron ions in HIS-DNIC induced genotoxicity is confirmed by plasmid nicking assay. Treatment of pUC19 plasmid with 1µM HIS-DNIC did not affect the plasmid supercoiling. Higher concentrations of HIS-DNIC induced single strand breaks. The effect was completely abrogated by addition of deferoxamine, a specific strong iron chelator. Our data reveal that formation of HIS-DNIC does not prevent DNA from iron-induced damage and imply that there is no direct interrelationship between iron-NO coordination and their mutual toxicity modulation.

Nitrosyl iron complexes--synthesis, structure and biology.

Nitrosyl complexes of iron are formed in living species in the presence of nitric oxide. They are considered a form in which NO can be stored and stabilized within a living cell. Upon entering a topic in bioinorganic chemistry the researcher faces a wide spectrum of issues concerning synthetic methods, the structure and chemical properties of the complex on the one hand, and its biological implications on the other. The aim of this review is to present the newest knowledge on nitrosyl iron complexes, summarizing the issues that are important for understanding the nature of nitrosyl iron complexes, their possible interactions, behavior in vitro and in vivo, handling of the preparations etc. in response to the growing interest in these compounds. Herein we focus mostly on the dinitrosyl iron complexes (DNICs) due to their prevailing occurrence in NO-treated biological samples. This article reviews recent knowledge on the structure, chemical properties and biological action of DNICs and some mononitrosyls of heme proteins. Synthetic methods are also briefly reviewed.

[Dinitrosyl iron complexes--structure and biological functions]. / Dinitrozylowe kompleksy zelaza--budowa i znaczenie biologiczne.

Formation of dinitrosyl iron complexes (DNICs), which can be described by general formula Fe(NO)2(L)2, where L is carbonyl-, nitrosyl- or imino- complexing ligand, was observed in many kinds of living organisms, in a wide spectrum of physiological conditions associated with inflammation, ischemia/reperfusion and cancer. Accumulation of DNICs coincides with intensified production of nitric oxide in macrophages, neurons, endothelial cells, Langerhans' cells and hepatocytes. Low-molecular thiol-containing DNICs (DNIC-(RS)2) show vasodilatory action and they are proposed to play a role of nitric oxide transducers and stabilizers. DNICs have been shown to modulate redox potential of the cell via inhibition of glutathione-dependent enzymes, such as glutathione reductase, S-transferase and peroxidase. Although there is a convincing experimental evidence for their NO and NO+ donating function, the nature of DNICs formed in biological systems, their stability and biological role is still a matter of discussion.

Variable inhibitory effects on the formation of dinitrosyl iron complexes by deferoxamine and salicylaldehyde isonicotinoyl hydrazone in K562 cells.

A prerequisite of dinitrosyl iron complexes (DNIC) formation is the presence of nitric oxide (NO), iron (Fe) and thiol/imidazole groups. The aim of this study was to investigate the influence of Fe chelators on the formation of DNIC in erythroid K562 cells. The cells were treated with lipophilic salicylaldehyde isonicotinoyl hydrazone (SIH) (0.1 mM) and hydrophilic deferoxamine mesylate (DFO) (1 mM), a membrane permeable and non permeable Fe chelator, respectively. Dinitrosyl Fe complexes were generated by addition of 0.07 mM diethylamine NO. The DNIC formation was recorded using electron paramagnetic resonance (EPR). Both chelators inhibited DNIC formation up to 50% after 6 hours of treatment. Taken together, our data suggest that an intracellular low molecular weight labile Fe pool (LIP) and protein-bound Fe participate in DNIC formation in K562 cells to a similar extent.