scholarly journals High-Field/High-Frequency EPR spectroscopy on synthetic melanin: on the origin of carbon-centered radicals

2021 ◽  
Author(s):  
João Vitor Paulin ◽  
Augusto Batagin-Neto ◽  
Boris Naydenov ◽  
Klaus Lips ◽  
Carlos F. O. Graeff
Keyword(s):  
Antioxidant Activity ◽  
Physicochemical Properties ◽  
Epr Spectroscopy ◽  
High Frequency ◽  
High Field ◽  
Broad Band ◽  
Metal Chelation

Among all pigments found in nature, melanin draws considerable attention for bioelectronics applications due to a set of physicochemical properties such as antioxidant activity, metal chelation, biocompatibility, broad-band absorbance throughout...

EPR Spectra from “EPR-Silent” Species:  High-Frequency and High-Field EPR Spectroscopy of Pseudotetrahedral Complexes of Nickel(II)

2002 ◽  
Vol 41 (17) ◽  
pp. 4478-4487 ◽  
Author(s):  
J. Krzystek ◽  
Ju-Hyun Park ◽  
Mark W. Meisel ◽  
Michael A. Hitchman ◽  
Horst Stratemeier ◽  
...  
Keyword(s):  
Epr Spectroscopy ◽  
High Frequency ◽  
High Field ◽  
Epr Spectra

Investigation of a Neat versus Magnetically Diluted Powdered Mononuclear MnII Complex by High-Field and High-Frequency EPR Spectroscopy

2004 ◽  
Vol 2004 (19) ◽  
pp. 3880-3886 ◽  
Author(s):  
Claire Mantel ◽  
Christian Philouze ◽  
Marie-Noëlle Collomb ◽  
Carole Duboc
Keyword(s):  
Epr Spectroscopy ◽  
High Frequency ◽  
High Field

High-frequency/high-field EPR spectroscopy of the high-spin ferrous ion in hexaaqua complexes

2005 ◽  
Vol 43 (S1) ◽  
pp. S130-S139 ◽  
Author(s):  
Joshua Telser ◽  
Joris van Slageren ◽  
Suriyakan Vongtragool ◽  
Martin Dressel ◽  
William M. Reiff ◽  
...  
Keyword(s):  
High Spin ◽  
Epr Spectroscopy ◽  
High Frequency ◽  
High Field ◽  
Ferrous Ion

scholarly journals Relationships Linking the Colour and Elemental Concentrations of Blossom Honeys with Their Antioxidant Activity: A Chemometric Approach

Agriculture ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 702
Author(s):  
Monika Kędzierska-Matysek ◽  
Anna Teter ◽  
Małgorzata Stryjecka ◽  
Piotr Skałecki ◽  
Piotr Domaradzki ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Physicochemical Properties ◽  
Black Locust ◽  
Antioxidant Properties ◽  
Principal Component ◽  
Botanical Origin ◽  
Antioxidant Parameters ◽  
Colour Parameters ◽  
Hue Angle ◽  
Chemometric Approach

The antioxidant activity of honey depends on the botanical origin, which also determines their physicochemical properties. In this study, a multivariate analysis was used to confirm potential relationships between the antioxidant properties and colour parameters, as well as the content of seven elements in five types of artisanal honey (rapeseed, buckwheat, linden, black locust, and multifloral). The type of honey was found to significantly influence most of its physicochemical properties, colour parameters, and the content of potassium, manganese and copper. Antioxidant parameters were shown to be significantly positively correlated with redness and concentrations of copper and manganese, but negatively correlated with the hue angle and lightness. The principal component analysis confirmed that the darkest buckwheat honey had the highest antioxidant activity in combination with its specific colour parameters and content of antioxidant minerals (manganese, copper and zinc). The level of these parameters can be potentially used for the identification of buckwheat honey.

scholarly journals Insights into the Antioxidant Mechanism of Newly Synthesized Benzoxazinic Nitrones: In Vitro and In Silico Studies with DPPH Model Radical

Antioxidants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1224
Author(s):  
Stefania Marano ◽  
Cristina Minnelli ◽  
Lorenzo Ripani ◽  
Massimo Marcaccio ◽  
Emiliano Laudadio ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Epr Spectroscopy ◽  
Point Of View ◽  
Uv Spectrophotometry ◽  
Design And Synthesis ◽  
Antioxidant Mechanism ◽  
Primary Mechanism ◽  
In Silico Studies ◽  
Wide Range

Synthetic nitrone spin-traps are being explored as therapeutic agents for the treatment of a wide range of oxidative stress-related pathologies, including but not limited to stroke, cancer, cardiovascular, and neurodegenerative diseases. In this context, increasing efforts are currently being made to the design and synthesis of new nitrone-based compounds with enhanced efficacy. The most researched nitrones are surely the ones related to α-phenyl-tert-butylnitrone (PBN) and 5,5-dimethyl-1-pyrroline N-oxide (DMPO) derivatives, which have shown to possess potent biological activity in many experimental animal models. However, more recently, nitrones with a benzoxazinic structure (3-aryl-2H-benzo[1,4]oxazin-N-oxides) have been demonstrated to have superior antioxidant activity compared to PBN. In this study, two new benzoxazinic nitrones bearing an electron-withdrawing methoxycarbonyl group on the benzo moiety (in para and meta positions respect to the nitronyl function) were synthesized. Their in vitro antioxidant activity was evaluated by two cellular-based assays (inhibition of AAPH-induced human erythrocyte hemolysis and cell death in human retinal pigmented epithelium (ARPE-19) cells) and a chemical approach by means of the α,α-diphenyl-β-picrylhydrazyl (DPPH) scavenging assay, using both electron paramagnetic resonance (EPR) spectroscopy and UV spectrophotometry. A computational approach was also used to investigate their potential primary mechanism of antioxidant action, as well as to rationalize the effect of functionalization on the nitrones reactivity toward DPPH, chosen as model radical in this study. Further insights were also gathered by exploring the nitrone electrochemical properties via cyclic voltammetry and by studying their kinetic behavior by means of EPR spectroscopy. Results showed that the introduction of an electron-withdrawing group in the phenyl moiety in the para position significantly increased the antioxidant capacity of benzoxazinic nitrones both in cell and cell-free systems. From the mechanistic point of view, the calculated results closely matched the experimental findings, strongly suggesting that the H-atom transfer (HAT) is likely to be the primary mechanism in the DPPH quenching.

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