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Mononuclear complexes of N-methylpropanoate-N,N-bis-(2-pyridylmethyl)amine (MPBMPA) and N-propanoate-N,N-bis-(2-pyridylmethyl)amine (HPBMPA) with first row transition metals from Mn to Cu were synthesized and characterized by spec...
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Mononuclear complexes of N-methylpropanoate-N,N-bis-(2-pyridylmethyl)amine (MPBMPA) and N-propanoate-N,N-bis-(2-pyridylmethyl)amine (HPBMPA) with first row transition metals from Mn to Cu were synthesized and characterized by spectroscopy (infrared, UV-visible), electrochemistry (cyclic voltammetry), microanalysis and in four cases X-ray crystallography. Structure of the complexes revealed high flexibility of these ligands that can adopt facial (Fe) and meridional (Cu) geometry. Activity in the degradation of reactive oxygen species (superoxide radical anion: superoxide dismutase (SOD)-like activity and hydrogen peroxide: catalase-like activity) was tested throughout the complex series in aqueous solutions. In connection with the catalytic dismutation of H_2O_2, bleaching tests with morin were also conducted in water. Comparison of the two ligands helped in elucidating the possible role of the carboxylate moiety in the different catalytic reactions. Although no general trends could be revealed between reactivity and constitution of the first coordination sphere, plausible explanations for differences are discussed individually for SOD like, catalase-like and bleaching activity.
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In the present work, 13 p-substituted phenols with different functional groups have been systematically evaluated as metHb substrates by means of HPLC analysis. Non-hyperbolic kinetics were observed and Hill coefficients in the 0....
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In the present work, 13 p-substituted phenols with different functional groups have been systematically evaluated as metHb substrates by means of HPLC analysis. Non-hyperbolic kinetics were observed and Hill coefficients in the 0.37-1.00 range were obtained. The catalytic constants and the Hill coefficients were found to be quantitatively correlated with two independent variables: the energy level of the highest-occupied molecular orbital (Ehomo), which describes the intrinsic redox activity of the substrates and the pK_a-values, which are related to substrate ionization. Oxygen evolution in the presence of each phenol derivative was also measured, and good correlation between peroxidase-like and catalase-like activities of the protein was observed. It is also shown that bovine metHb, although less active than other peroxi-dases, may represent a good alternative from an economical point of view for phenol removal processes. The equations here obtained may serve as a basis to further explore the potential use of metHb-mediated reactions in the treatment of phenols in wastewaters and to predict which phenol will be removed most efficiently under this treatment with satisfactory reliability.
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Bacterial infection has become a global health issue.The misuseantibiotics has been resulting in increased drug resistance and bioaccumulation.Therefore,developing a highly safe antibacterial agent,with high antibacterial performa...
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Bacterial infection has become a global health issue.The misuseantibiotics has been resulting in increased drug resistance and bioaccumulation.Therefore,developing a highly safe antibacterial agent,with high antibacterial performance is demanding.Inspired by the natural motors performing automated tasks in complicated living environments,we demonstrate tadpole-like nanoparticles(TNPs)with several functions,including high photothermal conversion efficiency,peroxidase-like catalytic activity,glutathione peroxidase-like activity,and catalase-like activity.TNPs produce hydroxyl radical(>>OH)at an extremely low concentrationhydrogen peroxide0.006%,which can damage bacterial cell membranes,proteins,and DNA.Moreover,the glutathione peroxidase-like activity disrupts the anti-oxidative mechanismbacteria and improves the permeabilitythe cell membranes,consequently enhancing the killing effectROS.In addition,TNPs possess tadpole-like asymmetry to overcome Brownian motion,demonstrating strong directional motion propelled by 02.The in vivo experiments indicate that TNPs could also shorten the inflammatory period and promote angiogenesis,making them a very promising antibacterial agent.
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Due to possessing an extremely small size and a large surface area per unit of volume, nanomaterials have specific characteristic physical, chemical, photochemical, and biological properties that are very useful in many new applic...
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Due to possessing an extremely small size and a large surface area per unit of volume, nanomaterials have specific characteristic physical, chemical, photochemical, and biological properties that are very useful in many new applications. Nanoparticles' catalytic activity and intrinsic ability in generating or scavenging reactive oxygen species in general can be used to mimic the catalytic activity of natural enzymes. Many nanoparticles with enzyme-like activities have been found, potentially capable of being applied for commercial uses, such as in biosensors, pharmaceutical processes, and the food industry. To date, a variety of nanoparticles, especially those formed from noble metals, have been determined to possess oxidase-like, peroxidase-like, catalase-like, and/or superoxide dismutase-like activity. The ability of nanoparticles to mimic enzymatic activity, especially peroxidase mimics, can be used in a variety of applications, such as detection of glucose in biological samples and waste water treatment. To study the enzyme-like activity of nanoparticles, the electron spin resonance method represents a critically important and convenient analytical approach for zero-time detection of the reactive substrates and products as well as for mechanism determination.
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AuNPs with enzyme-like features have received strong attention in different areas, although limited data is available in literature on their biological/industrial functions. NPs especially Au counterparts have been shown to functi...
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AuNPs with enzyme-like features have received strong attention in different areas, although limited data is available in literature on their biological/industrial functions. NPs especially Au counterparts have been shown to functionally mimic the activity of antioxidant enzyme. Indeed, due to low cytotoxicity and SPR characteristics of AuNPs, there are a great number of reports in which Au nanozymes yield promising responses in biomedical applications. In this review, we aim to overview the enzymatic activity of Au nanozymes along with their regulatory and controlling mechanisms. We have reviewed the effect of various factors such as dimension, morphology, functionalization and presence of hybrid materials on the catalytic activity of Au nanozymes as well as a detail survey on the oxidase, peroxidase, SOD, and CAT-like activities of Au nanozyme. Finally, the significance of Au nanozymes in mitigating oxidative stress followed by conclusion and challenges were reported. Based on this paper, we envision that Au nanozymes can be used as a promising material to prevent oxidative stress-stimulated disorders. (C) 2019 Elsevier B.V. All rights reserved.
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Nanozyme-based tumor catalytic therapy has attracted widespread attention in recent years. However, its therapeutic outcomes are diminished by many factors in the tumor microenvironment (TME), such as insufficient endogenous hydro...
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Nanozyme-based tumor catalytic therapy has attracted widespread attention in recent years. However, its therapeutic outcomes are diminished by many factors in the tumor microenvironment (TME), such as insufficient endogenous hydrogen peroxide (H2O2) concentration, hypoxia, and immunosuppressive microenvironment. Herein, an immunomodulation-enhanced nanozyme-based tumor catalytic therapy strategy is first proposed to achieve the synergism between nanozymes and TME regulation. TGF-beta inhibitor (TI)-loaded PEGylated iron manganese silicate nanoparticles (IMSN) (named as IMSN-PEG-TI) are constructed to trigger the therapeutic modality. The results show that IMSN nanozyme exhibits both intrinsic peroxidase-like and catalase-like activities under acidic TME, which can decompose H(2)O(2)into hydroxyl radicals (center dot OH) and oxygen (O-2), respectively. Besides, it is demonstrated that both IMSN and TI can regulate the tumor immune microenvironment, resulting in macrophage polarization from M2 to M1, and thus inducing the regeneration of H2O2, which can promote catalytic activities of IMSN nanozyme. The potent antitumor effect of IMSN-PEG-TI is proved by in vitro multicellular tumor spheroids (MCTS) and in vivo CT26-tumor-bearing mice models. It is believed that the immunomodulation-enhanced nanozyme-based tumor treatment strategy is a promising tool to kill cancer cells.
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? 2023 Elsevier B.V.In this study, a new Schiff base (H2L), which has not been recorded in the literature, and its metal complexes with general formula [ML].(H2O) [M: Cu(II) and Mn(II)] were synthesized and their structures were e...
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? 2023 Elsevier B.V.In this study, a new Schiff base (H2L), which has not been recorded in the literature, and its metal complexes with general formula [ML].(H2O) [M: Cu(II) and Mn(II)] were synthesized and their structures were elucidated. Techniques such as 1H- and 13C-NMR, FT-IR, UV–vis, TG-DTG, molar conductivity, magnetic susceptibility, ICP-OES, and elemental analysis were used to characterize the structures of the Schiff base and metal complexes. According to the analysis's findings, the complexes' metal:ligand ratio was 1:1. Additionally, the 6-311G(d,p) and LANL2DZ basis sets of the DFT/B3LYP method were used to calculate the optimized molecular geometries of the H2L and its metal complexes, respectively. Additionally, the synthesized compounds' molecular electrostatic potential (MEP) diagrams, frontier molecular orbitals (HOMO-LUMO), chemical shift values for the 1H- and 13C-NMR, vibrational frequencies, and wavelengths of electronic transitions were all determined. Experimentally obtained results were verified with theoretical data that matched well. [CuL].(H2O) and [MnL].(H2O) were examined for their catalase-like and catecholase-like enzymatic activities using volumetric and spectrophotometric techniques, respectively. For this objective, the catalytic activities of the synthesized molecules in the disproporsion reaction of H2O2 in the presence of 1-methylimidazole and the oxidation reaction of 3,5-di-tert-butylcatechol to 3,5-di-tert-butylquinone in aerobic medium were investigated. According to the enzyme-like studies, [MnL].(H2O) was more catalytically active than [CuL].(H2O) in both of the mentioned reactions.
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Chronic wounds caused by bacterial infections are a major challenge in
medical fields. The hypoxia condition extremely induces reactive oxygen
species (ROS) generation and upregulates the expression of hypoxia-inducible
factor,...
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Chronic wounds caused by bacterial infections are a major challenge in
medical fields. The hypoxia condition extremely induces reactive oxygen
species (ROS) generation and upregulates the expression of hypoxia-inducible
factor, both of which can increase the pro-inflammatory M1 subtype
macrophages production while reducing the anti-inflammatory M2 subtype
macrophages. Besides, bacteria-formed biofilms can hinder the penetration of
therapeutic agents. Encouraged by natural motors automatically executing
tasks, hypothesized that supplying sufficient oxygen (O_2) would
simultaneously drive therapeutic agent movement, rescue the hypoxic
microenvironment, and disrupt the vicious cycle of inflammation. Here, small
organic molecule-based nanoparticles (2TT-mC6B@Cu_(5.4)O NPs) that possess
high photothermal conversion efficiency and enzymatic activities are
developed, including superoxide dismutase-, catalase-, and glutathione
peroxidase-like activity. 2TT-mC6B@Cu_(5.4)O NPs exhibit superior
ROS-scavenging and O_2 production abilities that synergistically relieve
inflammation, alleviate hypoxia conditions, and promote their deep
penetration in chronic wound tissues. Transcriptome analysis further
demonstrates that 2TT-mC6B@Cu5.4O NPs inhibit biological activities inside
bacteria. Furthermore, in vivo experiments prove that 2TT-mC6B@Cu_(5.4)O
NPs-based hyperthermia can effectively eliminate bacteria in biofilms to
promote wound healing.
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The preparation of two homoleptic manganese(II)complexes [Mn(4'R-ind)2] [ind is the anion of 1,3-bis(2-pyridylimino)isoindoline,R = H(1),Me(2)] is described.Both complexes have been structurally characterized by UV-Vis and IR spec...
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The preparation of two homoleptic manganese(II)complexes [Mn(4'R-ind)2] [ind is the anion of 1,3-bis(2-pyridylimino)isoindoline,R = H(1),Me(2)] is described.Both complexes have been structurally characterized by UV-Vis and IR spectroscopies.Crystallographic characterization of the [Mn(ind)2](1)complex has shown that the overall geometry around the six-coordinate manganese(II)ion is described as a slightly distorted octahedron in an N6 donor set.These complexes represent functional model systems for manganese catalases.
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Stable nitroxide radicals have multiple biological effects, although the mechanisms underlying them are not fully understood. Their protective effect against oxidative damage has been mainly attributed to scavenging deleterious ra...
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Stable nitroxide radicals have multiple biological effects, although the mechanisms underlying them are not fully understood. Their protective effect against oxidative damage has been mainly attributed to scavenging deleterious radicals, oxidizing reduced metal ions and reducing oxyferryl centers of heme proteins. Yet, the potential of nitroxides to protect heme proteins against inactivation while suppressing or enhancing their catalytic activities has been largely overlooked. We have studied the effect of nitroxides, including TPO (2,2,6,6-tetramethylpiperidin-N-oxyl), 4-OH-TPO, 4-oxo-TPO and 3-carbamoyl proxyl, on the peroxidase-like activity of metmyoglobin (MbFe(III)) and methemoglobin (HbFe(III)) using nitrite as an electron donor by following heme absorption, H2O2 consumption, O-2 evolution and nitrite oxidation. The results demonstrate that the peroxidase-like activity is accompanied by a progressive heme inactivation where MbFeIII is far more resistant than HbFeIII. Nitroxides convert the peroxidase-like activity into catalase-like activity while inhibiting heme inactivation and nitrite oxidation in a dose-dependent manner. The nitroxide facilitates H2O2 dismutation, yet none of its reactions with any of the intermediates formed in these systems is rate-determining, and therefore its effect on the rate of the catalysis is hardly dependent on the kind of the nitroxide derivative and its concentration. The nitroxide at mu M concentrations range catalytically inhibits nitrite oxidation, and consequently prevents tyrosine nitration induced by heme protein/H2O2/ nitrite due to its fast oxidation by (NO2)-N-center dot forming the respective oxoammonium cation, which is reduced back to the nitroxide by H2O2 and by superoxide radical. The nitroxides are superior over common antioxidants, which their reaction with (NO2)-N-center dot always yields secondary radicals leading eventually to consumption of the antioxidant. A mechanism is proposed, and the kinetic simulations fit very well the experimental data in the case of MbFeIII where most of the rate constants of the reactions involved are independently known.
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