Study of Antioxidant Properties of Agents from the Perspective of Their Action Mechanisms

The creation and analysis of a large variety of existing methods for the evaluation of integrated antioxidant properties are quite relevant in connection with a range of biological mechanisms of the antioxidants (AO) action. In this work, the existing methods are correlated with mechanisms of antioxidant action. It is shown that the results obtained by various methods are mainly incomparable. This can be connected with the implementation of various mechanisms of antioxidant action in methods. The analysis of the literature data presented in this review indicates the difficulty of creating a universal method and the feasibility of using integrated approaches based on the use of several methods that implement and combine various mechanisms of the chemical conversion of antioxidants. This review describes methods for studying the chelating ability of antioxidants, except for methods based on electron and hydrogen atom transfer reactions, which are currently not widely covered in modern literature. With the description of each mechanism, special attention is paid to electrochemical methods, as the interaction of active oxygen metabolites of radical and non-radical nature with antioxidants has an electron/proton/donor-acceptor nature, which corresponds to the nature of electrochemical methods and suggests that they can be used to study the interaction.

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Structural and Antioxidant Properties of Compounds Obtained from Fe2+Chelation by Juglone and Two of Its Derivatives: DFT, QTAIM, and NBO Studies

Bioinorganic Chemistry and Applications ◽

10.1155/2016/8636409 ◽

2016 ◽

Vol 2016 ◽

pp. 1-13 ◽

Cited By ~ 5

Author(s):

Aymard Didier Tamafo Fouegue ◽

Julius Numbonui Ghogomu ◽

Désiré Bikélé Mama ◽

Nyiang Kennet Nkungli ◽

Elie Younang

Keyword(s):

Gas Phase ◽

Antioxidant Properties ◽

Nbo Analysis ◽

Hydrogen Atom Transfer ◽

Basis Sets ◽

Free Energies ◽

Dissociation Enthalpy ◽

B3lyp Level ◽

Ligand Charge Transfer ◽

Chelating Ability

The chelating ability of juglone and two of its derivatives towards Fe2+ion and the antioxidant activity (AOA) of the resulting chelates and complexes (in the presence of H2O and CH3OH as ligands) in gas phase is reported via bond dissociation enthalpy, ionization potential, proton dissociation enthalpy, proton affinity, and electron transfer enthalpy. The DFT/B3LYP level of theory associated with the 6-31+G(d,p) and 6-31G(d) Pople-style basis sets on the atoms of the ligands and the central Fe(II), respectively, was used. Negative chelation free energies obtained revealed that juglone derivatives possessing the O-H substituent (L2) have the greatest ability to chelate Fe2+ion. Apart from1B, thermodynamic descriptors of the AOA showed that the direct hydrogen atom transfer is the preferred mechanism of the studied molecules. NBO analysis showed that the Fe-ligand bonds are all formed through metal to ligand charge transfer. QTAIM studies revealed that among all the Fe-ligand bonds, the O1-Fe bond of1Ais purely covalent. The aforementioned results show that the ligands can be used to fight against Fe(II) toxicity, thus preserving human health, and fight against the deterioration of industrial products. In addition, most of the complexes studied have shown a better AOA than their corresponding ligands.

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Electron Donor–Acceptor Capacity of Selected Pharmaceuticals against COVID-19

Antioxidants ◽

10.3390/antiox10060979 ◽

2021 ◽

Vol 10 (6) ◽

pp. 979

Author(s):

Ana Martínez

Keyword(s):

Electron Donor ◽

Electron Acceptor ◽

Antioxidant Properties ◽

Free Radical Scavengers ◽

The Road ◽

Action Mechanisms ◽

First Case ◽

Donor Acceptor ◽

On The Road ◽

Acceptor Capacity

More than a year ago, the first case of infection by a new coronavirus was identified, which subsequently produced a pandemic causing human deaths throughout the world. Much research has been published on this virus, and discoveries indicate that oxidative stress contributes to the possibility of getting sick from the new SARS-CoV-2. It follows that free radical scavengers may be useful for the treatment of coronavirus 19 disease (COVID-19). This report investigates the antioxidant properties of nine antivirals, two anticancer molecules, one antibiotic, one antioxidant found in orange juice (Hesperidin), one anthelmintic and one antiparasitic (Ivermectin). A molecule that is apt for scavenging free radicals can be either an electron donor or electron acceptor. The results I present here show Valrubicin as the best electron acceptor (an anticancer drug with three F atoms in its structure) and elbasvir as the best electron donor (antiviral for chronic hepatitis C). Most antiviral drugs are good electron donors, meaning that they are molecules capable of reduzing other molecules. Ivermectin and Molnupiravir are two powerful COVID-19 drugs that are not good electron acceptors, and the fact that they are not as effective oxidants as other molecules may be an advantage. Electron acceptor molecules oxidize other molecules and affect the conditions necessary for viral infection, such as the replication and spread of the virus, but they may also oxidize molecules that are essential for life. This means that the weapons used to defend us from COVID-19 may also harm us. This study posits the idea that oxide reduction balance may help explain the toxicity or efficacy of these drugs. These results represent a further advance on the road towards understanding the action mechanisms of drugs used as possible treatments for COVID-19. Looking ahead, clinical studies are needed to define the importance of antioxidants in treating COVID-19.

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Comparative Study of Antioxidant Potential of Selected Dietary Vitamins; Computational Insights

Molecules ◽

10.3390/molecules24091646 ◽

2019 ◽

Vol 24 (9) ◽

pp. 1646 ◽

Cited By ~ 2

Author(s):

Dinesh R. Pandithavidana ◽

Samith B. Jayawardana

Keyword(s):

Electron Transfer ◽

Hydrogen Atom ◽

Aqueous Phase ◽

Density Functional ◽

Antioxidant Properties ◽

Hydrogen Atom Transfer ◽

Atom Transfer ◽

Antioxidant Action ◽

Polarized Continuum Model ◽

Primary Antioxidant

Density functional theory (DFT) was used to explore the antioxidant properties of some naturally occurring dietary vitamins, and the reaction enthalpies related to various mechanisms of primary antioxidant action, i.e., hydrogen atom transfer, single electron transfer–proton transfer, and sequential proton loss–electron transfer were discussed in detail. B3LYP, M05-2X, and M06-2X functionals were utilized in this work. For aqueous phase studies, the integral equation formalism polarized continuum model (IEF–PCM) was employed. From the outcomes, hydrogen atom transfer (HAT) was the most probable mechanism for the antioxidant action of this class of compounds. Comparison of found results with experimental data (available in literature), vitamin C possesses the lowest enthalpy values for both proton affinity (PA) and bond dissociation energy (BDE)in the aqueous phase, suggesting it as the most promising candidate as an antioxidant. Accordingly, these computational insights encourage the design of structurally novel, simple vitamins which will be more economical and beneficial in the pharmaceutical industry.

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How to express the antioxidant properties of substances properly?

Chemical Papers ◽

10.1007/s11696-021-01799-1 ◽

2021 ◽

Author(s):

Małgorzata Olszowy-Tomczyk

Keyword(s):

Oxidative Stress ◽

Reactive Oxygen Species ◽

Literature Review ◽

Antioxidant Activities ◽

Antioxidant Properties ◽

Reactive Oxygen ◽

The Body ◽

Universal Method ◽

Oxygen Species ◽

Good Tool

AbstractOxidative stress, associated with an imbalance between the oxidants (reactive oxygen species) and the antioxidants in the body, contributes to the development of many diseases. The body’s fight against reactive oxygen species is supported by antioxidants. Nowadays, there are too many analytical methods, but there is no one universal technique for assessing antioxidant properties. Moreover, the applied different ways of expressing the results lead to their incompatibility and unreasonable interpretation. The paper is a literature review concerning the most frequent ways of antioxidant activities expression and for an easy and universal method of the obtained results discussion. This paper is an attempt to point out their disadvantages and advantages. The manuscript can support the searching interpretation of the obtained results which will be a good tool for the development of a number of fields, especially medicine what can help in the future detection and treatment of many serious diseases. Graphic abstract

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Repeatable adhesion by proton donor-acceptor interaction of polymer brushes

Polymer ◽

10.1016/j.polymer.2017.05.035 ◽

2017 ◽

Vol 119 ◽

pp. 167-175 ◽

Cited By ~ 9

Author(s):

Hayato Yoshioka ◽

Chiharu Izumi ◽

Miki Shida ◽

Kazuo Yamaguchi ◽

Motoyasu Kobayashi

Keyword(s):

Polymer Brushes ◽

Proton Donor ◽

Acceptor Interaction ◽

Donor Acceptor

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Evaluation of Antioxidant Properties ofPhaulopsis fascisepalaC.B.Cl. (Acanthaceae)

Evidence-based Complementary and Alternative Medicine ◽

10.1093/ecam/nem098 ◽

2009 ◽

Vol 6 (2) ◽

pp. 227-231 ◽

Cited By ~ 28

Author(s):

S. A. Adesegun ◽

A. Fajana ◽

C. I. Orabueze ◽

H. A. B. Coker

Keyword(s):

Ascorbic Acid ◽

Leaf Extract ◽

Antioxidant Activities ◽

Antioxidant Properties ◽

Radical Scavenging ◽

Reducing Power ◽

Total Phenolic ◽

Chelating Ability

The antioxidant activities of crude extract ofPhaulopsis fascisepalaleaf were evaluated and compared with α-tocopherol and BHT as synthetic antioxidants and ascorbic acid as natural-based antioxidant.In vitro, we studied its antioxidative activities, radical-scavenging effects, Fe2+-chelating ability and reducing power. The total phenolic content was determined and expressed in gallic acid equivalent. The extract showed variable activities in all of thesein vitrotests. The antioxidant effect ofP. fascisepalawas strongly dose dependent, increased with increasing leaf extract dose and then leveled off with further increase in extract dose. Compared to other antioxidants used in the study, α-Tocopherol, ascorbic acid and BHT,P. fascisepalaleaf extract showed less scavenging effect on α,α,-diphenyl-β-picrylhydrazyl (DPPH) radical and less reducing power on Fe3+/ferricyanide complex but better Fe2+-chelating ability. These results revealed thein vitroantioxidant activity ofP.fascisepala.Further investigations are necessary to verify these activitiesin vivo.

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Thermodynamics of primary antioxidant action of flavonols in polar solvents

Acta Chimica Slovaca ◽

10.2478/acs-2019-0016 ◽

2019 ◽

Vol 12 (1) ◽

pp. 108-118 ◽

Cited By ~ 2

Author(s):

Martin Michalík ◽

Ján Rimarčík ◽

Vladimír Lukeš ◽

Erik Klein

Keyword(s):

Reaction Pathway ◽

Hydrogen Atom Transfer ◽

Antioxidant Effect ◽

Antioxidant Action ◽

Polar Solvents ◽

Polar Media ◽

Primary Antioxidant ◽

Intramolecular Hydrogen

Abstract Very recently, a report on the antioxidant activity of flavonoids has appeared, where authors concluded that Hydrogen Atom Transfer mechanism represents the thermodynamically preferred mechanism in polar media (https://doi.org/10.1016/j.foodres.2018.11.018). Unfortunately, serious errors in the theoretical part of the paper led to incorrect conclusions. For six flavonols (galangin, kaempferol, quercetin, morin, myricetin, and fisetin), reaction enthalpies related to three mechanisms of the primary antioxidant action were computed. Based on the obtained results, the role of intramolecular hydrogen bonds (IHB) in the thermodynamics of the antioxidant effect is presented. Calculations and the role of solvation enthalpies of proton and electron in the determination of thermodynamically preferred mechanism is also briefly explained and discussed. The obtained results are in accordance with published works considering the Sequential Proton-Loss Electron-Transfer thermodynamically preferred reaction pathway.

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Theoretical insight into the substituent effects on the antioxidant properties of 8-hydroxyquinoline derivatives in gas phase and in polar solvents

Canadian Journal of Chemistry ◽

10.1139/cjc-2017-0457 ◽

2018 ◽

Vol 96 (5) ◽

pp. 453-458

Author(s):

Anes El-Hadj Saïd ◽

Sidi Mohamed Mekelleche ◽

Taki-Eddine Ahmed Ardjani

Keyword(s):

Electron Transfer ◽

Gas Phase ◽

Antioxidant Properties ◽

Substituent Effects ◽

Hydrogen Atom Transfer ◽

Polar Solvents ◽

Antioxidant Power ◽

Theoretical Insight ◽

Insight Into

The objective of this work is to perform a theoretical analysis of the antioxidant properties of a series of 8-hydroxyquinolines (8-HQs) to rationalize the available experimental results and to design new potent 8-HQ derivatives. The study was carried out in gas phase and in methanol at the DFT/B3LYP/ 6-311++G(d,p) computational level. The formation of stable ArO• radicals is discussed on the basis of different mechanisms, namely, hydrogen atom transfer (HAT), single electron transfer followed by proton transfer (SET-PT), and single proton loss electron transfer (SPLET). The obtained results show that the HAT mechanism is, thermodynamically, more favoured in gas phase, whereas the SPLET pathway is more favoured in polar solvents. The calculated thermochemical descriptors allow classification of the antioxidant power of the studied compounds.

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Products Derived from Buchenavia tetraphylla Leaves Have In Vitro Antioxidant Activity and Protect Tenebrio molitor Larvae against Escherichia coli-Induced Injury

Pharmaceuticals ◽

10.3390/ph13030046 ◽

2020 ◽

Vol 13 (3) ◽

pp. 46

Author(s):

Tiago Fonseca Silva ◽

José Robson Neves Cavalcanti Filho ◽

Mariana Mirelle Lima Barreto Fonsêca ◽

Natalia Medeiros dos Santos ◽

Ana Carolina Barbosa da Silva ◽

...

Keyword(s):

Escherichia Coli ◽

Lethal Dose ◽

Antioxidant Properties ◽

Tenebrio Molitor ◽

Antioxidant Compounds ◽

Antioxidant Action ◽

Leaf Extracts ◽

E Coli ◽

Tenebrio Molitor Larvae

The relevance of oxidative stress in the pathogenesis of several diseases (including inflammatory disorders) has traditionally led to the search for new sources of antioxidant compounds. In this work, we report the selection of fractions with high antioxidant action from B. tetraphylla (BT) leaf extracts. In vitro methods (DPPH and ABTS assays; determination of phenolic and flavonoid contents) were used to select products derived from B. tetraphylla with high antioxidant action. Then, the samples with the highest potentials were evaluated in a model of injury based on the inoculation of a lethal dose of heat-inactivated Escherichia coli in Tenebrio molitor larvae. Due to its higher antioxidant properties, the methanolic extract (BTME) was chosen to be fractionated using Sephadex LH-20 column-based chromatography. Two fractions from BTME (BTFC and BTFD) were the most active fractions. Pre-treatment with these fractions protected larvae of T. molitor from the stress induced by inoculation of heat-inactivated E. coli. Similarly, BTFC and BTFD increased the lifespan of larvae infected with a lethal dose of enteroaggregative E. coli 042. NMR data indicated the presence of aliphatic compounds (terpenes, fatty acids, carbohydrates) and aromatic compounds (phenolic compounds). These findings suggested that products derived from B. tetraphylla leaves are promising candidates for the development of antioxidant and anti-infective agents able to treat oxidative-related dysfunctions.

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Artificial Intelligence (AI) to the Rescue: Deploying Machine Learning to Bridge the Biorelevance Gap in Antioxidant Assays

SLAS TECHNOLOGY Translating Life Sciences Innovation ◽

10.1177/2472630320962716 ◽

2020 ◽

pp. 247263032096271

Author(s):

Sunday Olakunle Idowu ◽

Amos Akintayo Fatokun

Keyword(s):

Oxidative Stress ◽

Artificial Intelligence ◽

Machine Learning ◽

Antioxidant Capacity ◽

Unmet Need ◽

Hydrogen Atom Transfer ◽

Support Vector ◽

Antioxidant Action ◽

Predictive Tool

Oxidative stress induced by excessive levels of reactive oxygen species (ROS) underlies several diseases. Therapeutic strategies to combat oxidative damage are, therefore, a subject of intense scientific investigation to prevent and treat such diseases, with the use of phytochemical antioxidants, especially polyphenols, being a major part. Polyphenols, however, exhibit structural diversity that determines different mechanisms of antioxidant action, such as hydrogen atom transfer (HAT) and single-electron transfer (SET). They also suffer from inadequate in vivo bioavailability, with their antioxidant bioactivity governed by permeability, gut-wall and first-pass metabolism, and HAT-based ROS trapping. Unfortunately, no current antioxidant assay captures these multiple dimensions to be sufficiently “biorelevant,” because the assays tend to be unidimensional, whereas biorelevance requires integration of several inputs. Finding a method to reliably evaluate the antioxidant capacity of these phytochemicals, therefore, remains an unmet need. To address this deficiency, we propose using artificial intelligence (AI)-based machine learning (ML) to relate a polyphenol’s antioxidant action as the output variable to molecular descriptors (factors governing in vivo antioxidant activity) as input variables, in the context of a biomarker selectively produced by lipid peroxidation (a consequence of oxidative stress), for example F2-isoprostanes. Support vector machines, artificial neural networks, and Bayesian probabilistic learning are some key algorithms that could be deployed. Such a model will represent a robust predictive tool in assessing biorelevant antioxidant capacity of polyphenols, and thus facilitate the identification or design of antioxidant molecules. The approach will also help to fulfill the principles of the 3Rs (replacement, reduction, and refinement) in using animals in biomedical research.

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