scholarly journals Ortho Isomeric Mn(III) N-Alkyl- and Alkoxyalkylpyridylporphyrins—Enhancers of Hyaluronan Degradation Induced by Ascorbate and Cupric Ions

2021 ◽  
Vol 22 (16) ◽  
pp. 8608
Author(s):  
Katarína Valachová ◽  
Peter Rapta ◽  
Nuno M. M. Moura ◽  
Ines Batinic-Haberle ◽  
Ladislav Šoltés
Keyword(s):  
Degradation Kinetics ◽  
Oxidative Degradation ◽  
Physiological Solution ◽  
Paramagnetic Resonance ◽  
Redox Active ◽  
Poor Outcomes ◽  
The Impact ◽  
Electron Paramagnetic ◽  
Insight Into ◽  
Biological Milieu

High levels of hyaluronic acid (HA) in tumors correlate with poor outcomes with several types of cancers due to HA-driven support of adhesion, migration and proliferation of cells. In this study we explored how to enhance the degradation of HA into low-molecular fragments, which cannot prevent the immune system to fight tumor proliferation and metastases. The physiological solution of HA was exposed to oxidative degradation by ascorbate and cupric ions in the presence of either one of three ortho isomeric Mn(III) substituted N-alkyl- and alkoxyalkylpyridylporphyrins or para isomeric Mn(III) N-methylpyridyl analog, commonly known as mimics of superoxide dismutase. The changes in hyaluronan degradation kinetics by four Mn(III) porphyrins were monitored by measuring the alteration in the dynamic viscosity of the HA solution. The ortho compounds MnTE-2-PyP5+ (BMX-010, AEOL10113), MnTnBuOE-2-PyP5+ (BMX-001) and MnTnHex-2-PyP5+ are able to redox cycle with ascorbate whereby producing H2O2 which is subsequently coupled with Cu(I) to produce the •OH radical essential for HA degradation. Conversely, with the para analog, MnTM-4-PyP5+, no catalysis of HA degradation was demonstrated, due to its inertness towards redox cycling with ascorbate. The impact of different Mn(III)-porphyrins on the HA decay was further clarified by electron paramagnetic resonance spectrometry. The ability to catalyze the degradation of HA in a biological milieu, in the presence of cupric ions and ascorbate under the conditions of high tumor oxidative stress provides further insight into the anticancer potential of redox-active ortho isomeric Mn(III) porphyrins.

scholarly journals The impact of particulate electron paramagnetic resonance oxygen sensors on fluorodeoxyglucose imaging characteristics detected via positron emission tomography

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Philip E. Schaner ◽  
Ly-Binh-An Tran ◽  
Bassem I. Zaki ◽  
Harold M. Swartz ◽  
Eugene Demidenko ◽  
...  
Keyword(s):  
Fdg Pet ◽  
Oxygen Sensor ◽  
Oxygen Sensors ◽  
Paramagnetic Resonance ◽  
Imaging Characteristics ◽  
Positron Emission ◽  
Pet Ct ◽  
Fdg Pet Ct ◽  
The Impact ◽  
Electron Paramagnetic

AbstractDuring a first-in-humans clinical trial investigating electron paramagnetic resonance tumor oximetry, a patient injected with the particulate oxygen sensor Printex ink was found to have unexpected fluorodeoxyglucose (FDG) uptake in a dermal nodule via positron emission tomography (PET). This nodule co-localized with the Printex ink injection; biopsy of the area, due to concern for malignancy, revealed findings consistent with ink and an associated inflammatory reaction. Investigations were subsequently performed to assess the impact of oxygen sensors on FDG-PET/CT imaging. A retrospective analysis of three clinical tumor oximetry trials involving two oxygen sensors (charcoal particulates and LiNc-BuO microcrystals) in 22 patients was performed to evaluate FDG imaging characteristics. The impact of clinically used oxygen sensors (carbon black, charcoal particulates, LiNc-BuO microcrystals) on FDG-PET/CT imaging after implantation in rat muscle (n = 12) was investigated. The retrospective review revealed no other patients with FDG avidity associated with particulate sensors. The preclinical investigation found no injected oxygen sensor whose mean standard uptake values differed significantly from sham injections. The risk of a false-positive FDG-PET/CT scan due to oxygen sensors appears low. However, in the right clinical context the potential exists that an associated inflammatory reaction may confound interpretation.

scholarly journals Anomalous chemically induced electron spin polarization in proton-coupled electron transfer reactions: insight into radical pair dynamics

2020 ◽  
Vol 11 (24) ◽  
pp. 6268-6274
Author(s):  
Alexander M. Brugh ◽  
Malcolm D. E. Forbes
Keyword(s):  
Electron Transfer ◽  
Ruthenium Complex ◽  
Transfer Reactions ◽  
Electron Spin Polarization ◽  
Paramagnetic Resonance ◽  
Time Resolved ◽  
Proton Coupled Electron Transfer ◽  
Chemically Induced ◽  
Electron Paramagnetic ◽  
Insight Into

Time-resolved electron paramagnetic resonance (TREPR) spectroscopy has been used to study the proton coupled electron transfer (PCET) reaction between a Ruthenium complex (Ru(bpz)(bpy)2) and several substituted hydroquinones (HQ).

scholarly journals Electron Paramagnetic Resonance - A Powerful Tool of Medical Biochemistry in Discovering Mechanisms of Disease and Treatment Prospects

2010 ◽  
Vol 29 (3) ◽  
pp. 175-188 ◽  
Author(s):  
Ivan Spasojević
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Epr Spectroscopy ◽  
Human Organism ◽  
Efficient Tool ◽  
Paramagnetic Resonance ◽  
Beneficial Effects ◽  
Ascorbyl Radical ◽  
Antioxidative Therapy ◽  
Electron Paramagnetic ◽  
Insight Into

Electron Paramagnetic Resonance - A Powerful Tool of Medical Biochemistry in Discovering Mechanisms of Disease and Treatment ProspectsIn pathophysiological conditions related to oxidative stress, the application of selected antioxidants could have beneficial effects on human health. Electron paramagnetic resonance (EPR) spectroscopy is a technique that provides unique insight into the redox biochemistry, due to its ability to: (i) distinguish and quantify different reactive species, such as hydroxyl radical, superoxide, carbon centered radicals, hydrogen atom, nitric oxide, ascorbyl radical, melanin, and others; (ii) evaluate the antioxidative capacity of various compounds, extracts and foods; (iii) provide information on other important parameters of biological systems. A combination of EPR spectroscopy and traditional biochemical methods represents an efficient tool in the studies of disease mechanisms and antioxidative therapy prospects, providing a more complete view into the redox processes in the human organism.

Relationship Between Spectroscopic and Structural Properties of Poly(meta/para Phenylene)

1999 ◽  
Vol 598 ◽  
Author(s):  
Cherif. Dridi ◽  
Joël. Davenas ◽  
Ahmed. Touhami ◽  
Hafedh. Ben Ouada ◽  
Hassen. Mâaref ◽  
...  
Keyword(s):  
Conjugated Polymer ◽  
Quantum Confinement ◽  
Blue Shift ◽  
Film Morphology ◽  
Energy Band Gap ◽  
Paramagnetic Resonance ◽  
Force Microscopy ◽  
Atomic Force ◽  
Electron Paramagnetic ◽  
Insight Into

ABSTRACTWe have used electron paramagnetic resonance (EPR) spectroscopy for investigating the properties of spins, such as those carried by polarons which carry both spin and charge in an electrosynthesized poly (meta/para phenylene) PMPP.Indeed, the study of their mobility provides an insight into the charge transport properties of the conjugated polymer in a microscopic scale.Moreover, we report a correlation between thin film morphology, chainlength and optical gap.Particularly, we show a blue shift upon decreasing chainlength. Furthermore, we have observed a blue shift of the energy band gap with the decrease of the surface grain size deduced from atomic force microscopy (AFM) analyses. This result has been explained in terms of quantum confinement.

Redox-active crown ethers. Electrochemical and electron paramagnetic resonance studies on alkali metal complexes of quinone crown ethers

1992 ◽  
Vol 114 (23) ◽  
pp. 8983-8991 ◽  
Author(s):  
Milagros Delgado ◽  
Robert E. Wolf ◽  
JudithAnn R. Hartman ◽  
Gillian McCafferty ◽  
Rahmi Yagbasan ◽  
...  
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Alkali Metal ◽  
Metal Complexes ◽  
Crown Ethers ◽  
Paramagnetic Resonance ◽  
Redox Active ◽  
Electron Paramagnetic ◽  
Alkali Metal Complexes

scholarly journals Interaction of iron ions with melanin

2019 ◽  
Author(s):  
Andrzej Czesław Żądło ◽  
Tadeusz Sarna
Keyword(s):  
Redox Reactions ◽  
Transition Metal Ions ◽  
Iron Binding ◽  
Iron Ions ◽  
Paramagnetic Resonance ◽  
Redox Active ◽  
Active Transition ◽  
Electron Paramagnetic ◽  
Aerobic And Anaerobic ◽  
Anaerobic System

One of the antioxidant roles of melanin is binding redox-active transition metal ions. The aim of this study was to examine the redox reactions accompanying iron binding by melanin. Two kinds of synthetic eumelanin were mixed with iron (II) and iron (III) in the presence and absence of citrate and ADP in the aerobic and anaerobic system. The iron binding was examined by electron paramagnetic resonance (EPR) spectroscopy and thiocyanate assay. Obtained results indicate that although melanin reduces iron (III) that is unbound to this polymer, binding of iron (II) is accompanied by its oxidation by melanin.

scholarly journals Electrochemically addressable trisradical rotaxanes organized within a metal–organic framework

2015 ◽  
Vol 112 (36) ◽  
pp. 11161-11168 ◽  
Author(s):  
Paul R. McGonigal ◽  
Pravas Deria ◽  
Idan Hod ◽  
Peyman Z. Moghadam ◽  
Alyssa-Jennifer Avestro ◽  
...  
Keyword(s):  
Solid State ◽  
Near Infrared ◽  
De Novo ◽  
Metal Organic Framework ◽  
Paramagnetic Resonance ◽  
Interlocked Molecules ◽  
Redox Active ◽  
Metal Organic ◽  
Electron Paramagnetic ◽  
Organic Framework

The organization of trisradical rotaxanes within the channels of a Zr6-based metal–organic framework (NU-1000) has been achieved postsynthetically by solvent-assisted ligand incorporation. Robust ZrIV–carboxylate bonds are forged between the Zr clusters of NU-1000 and carboxylic acid groups of rotaxane precursors (semirotaxanes) as part of this building block replacement strategy. Ultraviolet–visible–near-infrared (UV-Vis-NIR), electron paramagnetic resonance (EPR), and 1H nuclear magnetic resonance (NMR) spectroscopies all confirm the capture of redox-active rotaxanes within the mesoscale hexagonal channels of NU-1000. Cyclic voltammetry measurements performed on electroactive thin films of the resulting material indicate that redox-active viologen subunits located on the rotaxane components can be accessed electrochemically in the solid state. In contradistinction to previous methods, this strategy for the incorporation of mechanically interlocked molecules within porous materials circumvents the need for de novo synthesis of a metal–organic framework, making it a particularly convenient approach for the design and creation of solid-state molecular switches and machines. The results presented here provide proof-of-concept for the application of postsynthetic transformations in the integration of dynamic molecular machines with robust porous frameworks.

New insight into the photophysics and reactivity of trigonal and tetrahedral arylboron compounds

2016 ◽  
Vol 15 (9) ◽  
pp. 1124-1137 ◽  
Author(s):  
Willy G. Santos ◽  
João Pina ◽  
Douglas H. Burrows ◽  
Malcolm D. E. Forbes ◽  
Daniel R. Cardoso
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Steady State ◽  
Dft Calculations ◽  
Transient Absorption ◽  
Spin Trapping ◽  
Paramagnetic Resonance ◽  
Steady State Fluorescence ◽  
Ultrafast Transient Absorption ◽  
Electron Paramagnetic ◽  
Insight Into

The photophysics and reactivity of two tetraphenylborate salts and triphenylborane have been studied using ultrafast transient absorption, steady-state fluorescence, electron paramagnetic resonance with spin trapping, and DFT calculations.

scholarly journals Teas: Direct Test on Quality and Antioxidant Activity using Electron Paramagnetic Resonance Spectroscopy

2002 ◽  
Vol 16 (3-4) ◽  
pp. 371-378 ◽  
Author(s):  
M. A. Morsy
Keyword(s):  
Antioxidant Activity ◽  
Electron Paramagnetic Resonance ◽  
Green Tea ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Oxidative Degradation ◽  
Paramagnetic Species ◽  
Resonance Spectroscopy ◽  
Stable Free Radical ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic

The manufactured teas may conveniently be divided into three classes: Green teas, Oolongs (delicate black teas), and Black Teas. Several indirect methods are employed to measure the antioxidant activity of tea extracts that is basically takes place by monitoring the inhibition of oxidation of a suitable substrate using the extracts of antioxidant materials from the studies systems. This study is concerned with the results of electron paramagnetic resonance (EPR) spectroscopy that is utilized to investigate several categories of green and black teas: Twining Green Tea (TGT) of London, Rabea Green Tea (RGT) of Saudia, Chinese Green Tea (CGT) of China, English Breakfast Tea (EBT) of Ahmed Tea-London, and Rabea Black Tea (RBT) of Saudia. Three EPR signals from all the studied samples are observed. The assignment of these signals will discussed and correlated with the quality of leaves. Mainly, two paramagnetic species are considered to be responsible for the observed EPR signals; manganese(II)–protein system of the leaves and a stable free radical of aromatic origin. The study will provide facts on the dependency of radical signal on the oxidative degradation procedures of the studied samples. The intensity and feature of Mn(II)-EPR-signal is found to be related to the disintegration of tea leaves.

scholarly journals EPR Study of KO2 as a Source of Superoxide and •BMPO-OH/OOH Radical That Cleaves Plasmid DNA and Detects Radical Interaction with H2S and Se-Derivatives

Antioxidants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1286
Author(s):  
Anton Misak ◽  
Vlasta Brezova ◽  
Miroslav Chovanec ◽  
Karol Luspai ◽  
Muhammad Jawad Nasim ◽  
...  
Keyword(s):  
Plasmid Dna ◽  
Water Solution ◽  
Biological Effects ◽  
Physiological Solution ◽  
Oh Radicals ◽  
Paramagnetic Resonance ◽  
Superoxide Radical Anion ◽  
Epr Spin Trapping ◽  
Electron Paramagnetic ◽  
Radical Interaction

Superoxide radical anion (O2•−) and its derivatives regulate numerous physiological and pathological processes, which are extensively studied. The aim of our work was to utilize KO2 as a source of O2•− and the electron paramagnetic resonance (EPR) spin trapping 5-tert-butoxycarbonyl-5-methyl-1-pyrroline N-oxide (BMPO) technique for the preparation of •BMPO-OOH and/or •BMPO-OH radicals in water solution without DMSO. The method distinguishes the interactions of various compounds with •BMPO-OOH and/or •BMPO-OH radicals over time. Here, we show that the addition of a buffered BMPO-HCl mixture to powdered KO2 formed relatively stable •BMPO-OOH and •BMPO-OH radicals and H2O2, where the •BMPO-OOH/OH ratio depended on the pH. At a final pH of ~6.5–8.0, the concentration of •BMPO-OOH radicals was ≥20 times higher than that of •BMPO-OH, whereas at pH 9.0–10.0, the •BMPO-OH radicals prevailed. The •BMPO-OOH/OH radicals effectively cleaved the plasmid DNA. H2S decreased the concentration of •BMPO-OOH/OH radicals, whereas the selenium derivatives 1-methyl-4-(3-(phenylselanyl) propyl) piperazine and 1-methyl-4-(4-(phenylselanyl) butyl) piperazine increased the proportion of •BMPO-OH over the •BMPO-OOH radicals. In conclusion, the presented approach of using KO2 as a source of O2•−/H2O2 and EPR spin trap BMPO for the preparation of •BMPO-OOH/OH radicals in a physiological solution could be useful to study the biological effects of radicals and their interactions with compounds.

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