Reducing Activity of Polyphenols with Stable Radicals of the TTM Series. Electron Transfer versus H-Abstraction Reactions in Flavan-3-ols

Jiménez, Aurora; Selga, Ariadna; Torres, Josep Lluís; Juliá, Luís

doi:10.1021/ol048015f

Cited by 72 publications

(51 citation statements)

References 31 publications

(17 reference statements)

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“…ORAC, TRAP, and chemiluminescence are hydrogen atom transfer-based methods, whereas FRAP and CUPRAC are single electron transfer methods [85]. DPPH and TEAC methods were regarded as methods using both hydrogen and single electron transfer, as the radicals in these cases can be scavenged by either electron reduction or radical quenching that involves hydrogen transfer [85, 86]. DPPH scavenging, TEAC assay, ferric reducing antioxidant power, OH • scavenging, the phosphomolybdenum method, and beta-carotene linoleate bleaching are applied in vitro , while the lipid peroxidase, catalase, and glutathione peroxidase activity assays are techniques used in vivo [18].…”

Section: Analytical Methods Applied To Antioxidant Content and Antmentioning

confidence: 99%

Antioxidant Capacity Determination in Plants and Plant‐Derived Products: A Review

Pisoschi

Cîmpeanu

et al. 2016

Oxidative Medicine and Cellular Longevity

215

149

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The present paper aims at reviewing and commenting on the analytical methods applied to antioxidant and antioxidant capacity assessment in plant-derived products. Aspects related to oxidative stress, reactive oxidative species' influence on key biomolecules, and antioxidant benefits and modalities of action are discussed. Also, the oxidant-antioxidant balance is critically discussed. The conventional and nonconventional extraction procedures applied prior to analysis are also presented, as the extraction step is of pivotal importance for isolation and concentration of the compound(s) of interest before analysis. Then, the chromatographic, spectrometric, and electrochemical methods for antioxidant and antioxidant capacity determination in plant-derived products are detailed with respect to their principles, characteristics, and specific applications. Peculiarities related to the matrix characteristics and other factors influencing the method's performances are discussed. Health benefits of plants and derived products are described, as indicated in the original source. Finally, critical and conclusive aspects are given when it comes to the choice of a particular extraction procedure and detection method, which should consider the nature of the sample, prevalent antioxidant/antioxidant class, and the mechanism underlying each technique. Advantages and disadvantages are discussed for each method.

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Section: Analytical Methods Applied To Antioxidant Content and Antmentioning

confidence: 99%

Antioxidant Capacity Determination in Plants and Plant‐Derived Products: A Review

Pisoschi

Cîmpeanu

et al. 2016

Oxidative Medicine and Cellular Longevity

215

149

View full text Add to dashboard Cite

show abstract

“…The DPPH assay is classified as a single-electron transfer reaction that may be neutralized by the antioxidant either by direct reduction via electron transfers or by radical quenching via H atom transfer [23]. One of the limitations of this assay is the poor correlation between DPPH chemical structure with free radicals produced in biological systems [24].…”

Section: Introductionmentioning

confidence: 99%

Comparison of Brazilian Plants Used to Treat Gastritis on the Oxidative Burst ofHelicobacter pylori-Stimulated Neutrophil

Bonacorsi

Fonseca

Raddi

et al. 2013

Evidence-Based Complementary and Alternative Medicine

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Ten Brazilian medicinal plants used to treat gastritis and ulcers were carefully selected on the basis of ethnopharmacological importance and antiulcerogenic activity previously described. The antioxidant activity of the methanolic extracts was determined in analysis conditions that simulate a real biological activity on inhibition of the oxidative burst induced in neutrophils using Helicobacter pylori as activator, by a luminol-amplified chemiluminescence assay. The extracts, at low concentration (5 μg/mL), exhibited a large variation in inhibitory effects of H. pylori-induced oxidative burst ranging from 48% inhibition to inactive, but all extracts, excluding Byrsonima intermedia, had inhibitory activity over 80% at the concentration of 100 μg/mL. The total suppressive antioxidant capacity measured as the effective concentration, which represents the extract concentration producing 50% inhibition of the chemiluminescence induced by H. pylori, varies from 27.2 to 56.8 μg/mL and was in the following order: Qualea parviflora > Qualea multiflora > Alchornea triplinervia > Qualea grandiflora > Anacardium humile > Davilla elliptica > Mouriri pusa > Byrsonima basiloba > Alchornea glandulosa > Byrsonima intermedia. The main groups of compounds in tested extracts are presented. Differences in the phytochemical profile, quantitatively and qualitatively, of these plants can explain and justify their protective effect on the gastric mucosa caused by the neutrophil-generated ROS that occurs when H. pylori displays its evasion mechanisms.

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“…The DPH • assay was used to investigate the ability of the L ligand and Ln–L complexes to quench the stable DPPH • radical. DPPH • can be converted by antioxidant to 2,2‐diphenyl‐1‐picryl hydrazine either by radical quenching via hydrogen atom transfer (HAT) or by direct reduction through electron transfer (EA) mechanisms . Figure clearly shows that Ln–L complexes are more effective than L in quenching DPPH.…”

Section: Resultsmentioning

confidence: 99%

Synthesis, density functional theory calculations and luminescence of lanthanide complexes with 2,6‐bis[(3‐methoxybenzylidene)hydrazinocarbonyl] pyridine Schiff base ligand

et al. 2017

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A pyridine-diacylhydrazone Schiff base ligand, L = 2,6-bis [(3-methoxy benzylidene) hydrazinocarbonyl]pyridine was prepared and characterized by single crystal X-ray diffraction. homogeneous and heterogeneous catalysis. [16][17][18] Following our recently published work towards the complexation of lanthanide(III) nitrate salts with dimethyl pyridine-2,6-dicarboxylate, we were interested in the synthesis of a 2,6-bis [(3-methoxybenzylidene)hydrazine carbonyl]pyridine L ligand derived from dimethyl pyridine-2,6-dicarboxylate ligand. [19] In comparison with dimethyl pyridine-2,6-dicarboxylate ligand, the L ligand possesses more coordination sites that can bind and stabilize different lanthanide metal ions with high coordination numbers. Moreover it has flexible groups that can accommodate and protect lanthanide metal atoms from solvent molecules, which avoid non-radiative deactivation processes. [20] Moreover, L is efficient in the displacement of water molecules present in the coordination sphere of lanthanide ions that quenches the luminescence by absorption of the emitted radiation in the vibrational excitation processes via the vibrational levels of the O-H of water molecules. [21] This work reports the synthesis of the L ligand by a condensation reaction between 2-methoxybenzaldehyde and 2,6-bis(hydrazinocarbonyl)pyridine in ethanol and describes its crystal structure. Additionally the coordinating behavior of L with lanthanide metals (Ln = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy and Er) has been investigated by elemental analysis, conductivity measurements, spectral analysis (IR, NMR, UV-Vis and mass) and thermal studies.The antioxidant activity and photoluminescence properties of L and Ln-L have been investigated.

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Reducing Activity of Polyphenols with Stable Radicals of the TTM Series. Electron Transfer versus H-Abstraction Reactions in Flavan-3-ols

Cited by 72 publications

References 31 publications

Antioxidant Capacity Determination in Plants and Plant‐Derived Products: A Review

Antioxidant Capacity Determination in Plants and Plant‐Derived Products: A Review

Comparison of Brazilian Plants Used to Treat Gastritis on the Oxidative Burst ofHelicobacter pylori-Stimulated Neutrophil

Synthesis, density functional theory calculations and luminescence of lanthanide complexes with 2,6‐bis[(3‐methoxybenzylidene)hydrazinocarbonyl] pyridine Schiff base ligand

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