scholarly journals Design of an Antioxidant Nitrone Scaffold Based on Plant Pigments

2021 ◽  
Author(s):  
Amanda Capistrano Pinheiro ◽  
Rodrigo Boni Fazzi ◽  
Larissa Cerrato Esteves ◽  
Caroline Oliveira Machado ◽  
Felipe Augusto Dörr ◽  
...  
Keyword(s):  
Transient Absorption ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Hydrolytic Stability ◽  
Nitroxide Radical ◽  
Natural Antioxidants ◽  
Transient Absorption Spectroscopy ◽  
Alkaline Media ◽  
Phenolic Antioxidants ◽  
Radical Scavenger ◽  
Resonance Spectroscopy

<div> <div> <div> <p>Nitrones derived from natural antioxidants are emerging as highly specific therapeutics against various human diseases, including stroke, neurodegenerative pathologies, and cancer. However, the development of useful pseudo-natural nitrones requires the judicious choice of a secondary metabolite as the precursor. Betalains are nitrogen-containing natural pigments that exhibit marked antioxidant capacity and pharmacological properties and, hence, are ideal candidates for designing multifunctional nitrones. In this work, we describe the semisynthesis and properties of a biocompatible, antioxidant betalain-nitrone called OxiBeet. This bio-based compound is a better radical scavenger than ascorbic acid, gallic acid, and most non-phenolic antioxidants and undergoes concerted proton-coupled electron transfer. The autoxidation of OxiBeet produces a persistent nitroxide radical, which, herein, is studied via electron paramagnetic resonance spectroscopy. In addition, femtosecond transient absorption spectroscopy reveals that excited state formation is not required for the oxidation of OxiBeet. The results are compared with those obtained using betanin, a natural betalain, and pBeet, the imine analog of OxiBeet. The findings of this study will enable the development of antioxidant nitrones based on the novel N-oxide 1,7-diazaheptamethinium scaffold and betalain dyes with enhanced hydrolytic stability in aqueous alkaline media. </p> </div> </div> </div>

scholarly journals Design of an Antioxidant Nitrone Scaffold Based on Plant Pigments

2021 ◽  
Author(s):  
Amanda Capistrano Pinheiro ◽  
Rodrigo Boni Fazzi ◽  
Larissa Cerrato Esteves ◽  
Caroline Oliveira Machado ◽  
Felipe Augusto Dörr ◽  
...  
Keyword(s):  
Transient Absorption ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Hydrolytic Stability ◽  
Nitroxide Radical ◽  
Natural Antioxidants ◽  
Transient Absorption Spectroscopy ◽  
Alkaline Media ◽  
Phenolic Antioxidants ◽  
Radical Scavenger ◽  
Resonance Spectroscopy

Nitrones derived from natural antioxidants are emerging as highly specific therapeutics for the treatment of various human diseases, including stroke, neurodegenerative pathologies, and cancer. However, the development of useful pseudo-natural nitrones requires the judicious choice of a secondary metabolite as precursor. Betalains are nitrogen-containing natural pigments that exhibit marked antioxidant and pharmacological properties and, hence, are ideal candidates for the design of multifunctional nitrones. In this work, we describe the semisynthesis and properties of a biocompatible and antioxidant betalain-nitrone named OxiBeet. This bio-based compound is a better radical scavenger than ascorbic acid, gallic acid and most non-phenolic antioxidants and undergoes concerted proton-coupled electron transfer. The autoxidation of OxiBeet gives rise to a persistent nitroxide radical, which was studied by electron paramagnetic resonance spectroscopy. Femtosecond transient absorption spectroscopy reveals that excited state formation is not required for the oxidation of OxiBeet. The results are compared with those obtained using betanin, a natural betalain, and pBeet, the imine analogue of OxiBeet. The findings in this study will enable the development of antioxidant nitrones based on the novel <i>N</i>-oxide 1,7-diazaheptamethinium scaffold and betalain dyes with enhanced hydrolytic stability in aqueous alkaline media.

scholarly journals Design of an Antioxidant Nitrone Scaffold Based on Plant Pigments

2021 ◽  
Author(s):  
Amanda Capistrano Pinheiro ◽  
Rodrigo Boni Fazzi ◽  
Larissa Cerrato Esteves ◽  
Caroline Oliveira Machado ◽  
Felipe Augusto Dörr ◽  
...  
Keyword(s):  
Transient Absorption ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Hydrolytic Stability ◽  
Nitroxide Radical ◽  
Natural Antioxidants ◽  
Transient Absorption Spectroscopy ◽  
Alkaline Media ◽  
Phenolic Antioxidants ◽  
Radical Scavenger ◽  
Resonance Spectroscopy

<div> <div> <div> <p>Nitrones derived from natural antioxidants are emerging as highly specific therapeutics against various human diseases, including stroke, neurodegenerative pathologies, and cancer. However, the development of useful pseudo-natural nitrones requires the judicious choice of a secondary metabolite as the precursor. Betalains are nitrogen-containing natural pigments that exhibit marked antioxidant capacity and pharmacological properties and, hence, are ideal candidates for designing multifunctional nitrones. In this work, we describe the semisynthesis and properties of a biocompatible, antioxidant betalain-nitrone called OxiBeet. This bio-based compound is a better radical scavenger than ascorbic acid, gallic acid, and most non-phenolic antioxidants and undergoes concerted proton-coupled electron transfer. The autoxidation of OxiBeet produces a persistent nitroxide radical, which, herein, is studied via electron paramagnetic resonance spectroscopy. In addition, femtosecond transient absorption spectroscopy reveals that excited state formation is not required for the oxidation of OxiBeet. The results are compared with those obtained using betanin, a natural betalain, and pBeet, the imine analog of OxiBeet. The findings of this study will enable the development of antioxidant nitrones based on the novel N-oxide 1,7-diazaheptamethinium scaffold and betalain dyes with enhanced hydrolytic stability in aqueous alkaline media. </p> </div> </div> </div>

scholarly journals Oxidative stability of the lipid fraction in cookies – the EPR study

Nukleonika ◽  
2015 ◽  
Vol 60 (3) ◽  
pp. 469-473 ◽  
Author(s):  
Katarzyna Zawada ◽  
Mariola Kozłowska ◽  
Anna Żbikowska
Keyword(s):  
Electron Paramagnetic Resonance Spectroscopy ◽  
Lipid Fraction ◽  
Natural Antioxidants ◽  
Biologically Active ◽  
Rosemary Extract ◽  
Resonance Spectroscopy ◽  
Bakery Products ◽  
Paramagnetic Resonance ◽  
Electron Paramagnetic ◽  
Active Substances

Abstract Cookies are a group of convenient food products that are popular among consumers. They may contain high amounts of fats, which can be prone to oxidation. To retard the oxidative deterioration, synthetic and natural antioxidants may be added. Herb and spice extracts can be sources of natural biologically active substances with antioxidant activity. In this work, electron paramagnetic resonance spectroscopy was used to monitor the lipid oxidation in cookies with rosemary and thyme extracts subjected to the storage in elevated temperature. It was shown that thyme extract can be used as a natural antioxidant source for the preparation of bakery products, while the rosemary extract should be used with care in fat-rich products exposed to high temperatures.

scholarly journals A Comparison of Cysteine-Conjugated Nitroxide Spin Labels for Pulse Dipolar EPR Spectroscopy

Molecules ◽  
2021 ◽  
Vol 26 (24) ◽  
pp. 7534
Author(s):  
Katrin Ackermann ◽  
Alexandra Chapman ◽  
Bela E. Bode
Keyword(s):  
Materials Science ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Protein Structures ◽  
Nitroxide Radical ◽  
Structural Heterogeneity ◽  
Site Directed Mutagenesis ◽  
Spin Labels ◽  
Resonance Spectroscopy ◽  
Side Chains ◽  
Distance Distributions

The structure-function and materials paradigms drive research on the understanding of structures and structural heterogeneity of molecules and solids from materials science to structural biology. Functional insights into complex architectures are often gained from a suite of complementary physicochemical methods. In the context of biomacromolecular structures, the use of pulse dipolar electron paramagnetic resonance spectroscopy (PDS) has become increasingly popular. The main interest in PDS is providing long-range nanometre distance distributions that allow for identifying macromolecular topologies, validating structural models and conformational transitions as well as docking of quaternary complexes. Most commonly, cysteines are introduced into protein structures by site-directed mutagenesis and modified site-specifically to a spin-labelled side-chain such as a stable nitroxide radical. In this contribution, we investigate labelling by four different commercial labelling agents that react through different sulfur-specific reactions. Further, the distance distributions obtained are between spin-bearing moieties and need to be related to the protein structure via modelling approaches. Here, we compare two different approaches to modelling these distributions for all four side-chains. The results indicate that there are significant differences in the optimum labelling procedure. All four spin-labels show differences in the ease of labelling and purification. Further challenges arise from the different tether lengths and rotamers of spin-labelled side-chains; both influence the modelling and translation into structures. Our comparison indicates that the spin-label with the shortest tether in the spin-labelled side-group, (bis-(2,2,5,5-Tetramethyl-3-imidazoline-1-oxyl-4-yl) disulfide, may be underappreciated and could increase the resolution of structural studies by PDS if labelling conditions are optimised accordingly.

Thymine Dimerization Induced by Oxidative DNA Lesions and Epigenetic Intermediates via Triplet-Triplet Energy Transfer

2020 ◽  
Author(s):  
Mauricio Lineros-Rosa ◽  
Antonio Francés-Monerris ◽  
Antonio Monari ◽  
Miguel Angél Miranda ◽  
Virginie Lhiaubet-Vallet
Keyword(s):  
Energy Transfer ◽  
Excitation Energy ◽  
Transient Absorption ◽  
Theoretical Calculations ◽  
Dna Lesions ◽  
Transient Absorption Spectroscopy ◽  
Triplet Energy ◽  
Pyrimidine Dimers ◽  
Triplet Energy Transfer ◽  
Dna Nucleobases

Interaction of nucleic acids with light is a scientific question of paramount relevance not only in the understanding of life functioning and evolution, but also in the insurgence of diseases such as malignant skin cancer and in the development of biomarkers and novel light-assisted therapeutic tools. This work shows that the UVA portion of sunlight, not absorbed by canonical DNA nucleobases, can be absorbed by 5-formyluracil (ForU) and 5-formylcytosine (ForC), two ubiquitous oxidative lesions and epigenetic intermediates present in living beings in natural conditions. We measure the strong propensity of these molecules to populate triplet excited states able to transfer the excitation energy to thymine-thymine dyads, inducing the formation of the highly toxic and mutagenic cyclobutane pyrimidine dimers (CPDs). By using steady-state and transient absorption spectroscopy, NMR, HPLC, and theoretical calculations, we quantify the differences in the triplet-triplet energy transfer mediated by ForU and ForC, revealing that the former is much more efficient in delivering the excitation energy and producing the CPD photoproduct. Although significantly slower than ForU, ForC is also able to harm DNA nucleobases and therefore this process has to be taken into account as a viable photosensitization mechanism. The present findings evidence a rich photochemistry crucial to understand DNA photodamage and of potential use in the development of biomarkers and non-conventional photodynamic therapy agents.

Excited-State Dynamics in the RNA Nucleotide Uridine 5’-Monophosphate Investigated by Femtosecond Broadband Transient Absorption Spectroscopy

2019 ◽  
Author(s):  
Matthew M. Brister ◽  
Carlos Crespo-Hernández
Keyword(s):  
Excited State ◽  
Excited States ◽  
Ground State ◽  
Transient Absorption ◽  
Electronic Energy ◽  
Transient Absorption Spectroscopy ◽  
Electronic Relaxation ◽  
Vibrationally Excited ◽  
Excited State Dynamics ◽  
Π State

<p></p><p> Damage to RNA from ultraviolet radiation induce chemical modifications to the nucleobases. Unraveling the excited states involved in these reactions is essential, but investigations aimed at understanding the electronic-energy relaxation pathways of the RNA nucleotide uridine 5’-monophosphate (UMP) have not received enough attention. In this Letter, the excited-state dynamics of UMP is investigated in aqueous solution. Excitation at 267 nm results in a trifurcation event that leads to the simultaneous population of the vibrationally-excited ground state, a longlived <sup>1</sup>n<sub>O</sub>π* state, and a receiver triplet state within 200 fs. The receiver state internally convert to the long-lived <sup>3</sup>ππ* state in an ultrafast time scale. The results elucidate the electronic relaxation pathways and clarify earlier transient absorption experiments performed for uracil derivatives in solution. This mechanistic information is important because long-lived nπ* and ππ* excited states of both singlet and triplet multiplicities are thought to lead to the formation of harmful photoproducts.</p><p></p>

In vitro Lipolysis as a Tool for the Establishment of IVIVC for Lipid-Based Drug Delivery Systems

2019 ◽  
Vol 16 (8) ◽  
pp. 688-697
Author(s):  
Ravinder Verma ◽  
Deepak Kaushik
Keyword(s):  
Drug Delivery ◽  
Ph Value ◽  
Electron Paramagnetic Resonance Spectroscopy ◽  
Rapid Screening ◽  
Resonance Spectroscopy ◽  
Fed State ◽  
In Vitro Lipolysis ◽  
Ph Stat

: In vitro lipolysis has emerged as a powerful tool in the development of in vitro in vivo correlation for Lipid-based Drug Delivery System (LbDDS). In vitro lipolysis possesses the ability to mimic the assimilation of LbDDS in the human biological system. The digestion medium for in vitro lipolysis commonly contains an aqueous buffer media, bile salts, phospholipids and sodium chloride. The concentrations of these compounds are defined by the physiological conditions prevailing in the fasted or fed state. The pH of the medium is monitored by a pH-sensitive electrode connected to a computercontrolled pH-stat device capable of maintaining a predefined pH value via titration with sodium hydroxide. Copenhagen, Monash and Jerusalem are used as different models for in vitro lipolysis studies. The most common approach used in evaluating the kinetics of lipolysis of emulsion-based encapsulation systems is the pH-stat titration technique. This is widely used in both the nutritional and the pharmacological research fields as a rapid screening tool. Analytical tools for the assessment of in vitro lipolysis include HPLC, GC, HPTLC, SEM, Cryo TEM, Electron paramagnetic resonance spectroscopy, Raman spectroscopy and Nanoparticle Tracking Analysis (NTA) for the characterization of the lipids and colloidal phases after digestion of lipids. Various researches have been carried out for the establishment of IVIVC by using in vitro lipolysis models. The current publication also presents an updated review of various researches in the field of in vitro lipolysis.

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