scholarly journals Synthesis, DFT Calculations, and In Vitro Antioxidant Study on Novel Carba-Analogs of Vitamin E

Antioxidants ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 589 ◽  
Author(s):  
Aneta Baj ◽  
Jakub Cedrowski ◽  
Ewa Olchowik-Grabarek ◽  
Artur Ratkiewicz ◽  
Stanislaw Witkowski
Keyword(s):  
Antioxidant Activity ◽  
Electron Transfer ◽  
Vitamin E ◽  
Density Functional ◽  
Lone Pair ◽  
Hydrogen Atom Transfer ◽  
Hydroxyl Group ◽  
Styrene Oxidation ◽  
Chain Breaking

Vitamin E is the most active natural lipophilic antioxidant with a broad spectrum of biological activity. α-Tocopherol (α-T), the main representative of the vitamin E family, is a strong inhibitor of lipid peroxidation as a chain-breaking antioxidant. Antioxidant and antiradical properties of vitamin E result from the presence of a phenolic hydroxyl group at the C-6 position. Due to stereoelectronic effects in the dihydropyranyl ring, the dissociation enthalpy for phenolic O–H bond (BDEOH) is reduced. The high chain-breaking reactivity of α-T is mainly attributed to orbital overlapping of the 2p-type lone pair on the oxygen atom (O1) in para position to the phenolic group, and the aromatic π-electron system. The influence of the O1 atom on the antioxidant activity of vitamin E was estimated quantitatively. The all-rac-1-carba-α-tocopherol was synthesized for the first time. Along with model compounds, 1-carba-analog of Trolox and its methyl ester were screened for their in vitro antioxidant activity by inhibition of styrene oxidation, and for the radical-reducing properties by means of 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH) scavenging assay. To study the antioxidant activity, density functional theory (DFT) was also applied. Reaction enthalpies related to HAT (hydrogen atom transfer), SET–PT (sequential electron transfer—proton transfer), and SPLET (sequential proton loss—electron transfer) mechanisms were calculated.

scholarly journals Green One-Pot Synthesis of Coumarin-Hydroxybenzohydrazide Hybrids and Their Antioxidant Potency

Antioxidants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1106
Author(s):  
Marko R. Antonijević ◽  
Dušica M. Simijonović ◽  
Edina H. Avdović ◽  
Andrija Ćirić ◽  
Zorica D. Petrović ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Electron Transfer ◽  
Density Functional ◽  
Electron Transfer Reaction ◽  
Hydrogen Atom Transfer ◽  
Special Importance ◽  
Theory Approach ◽  
One Pot ◽  
Antioxidant Potency

Compounds from the plant world that possess antioxidant abilities are of special importance for the food and pharmaceutical industry. Coumarins are a large, widely distributed group of natural compounds, usually found in plants, often with good antioxidant capacity. The coumarin-hydroxybenzohydrazide derivatives were synthesized using a green, one-pot protocol. This procedure includes the use of an environmentally benign mixture (vinegar and ethanol) as a catalyst and solvent, as well as very easy isolation of the desired products. The obtained compounds were structurally characterized by IR and NMR spectroscopy. The purity of all compounds was determined by HPLC and by elemental microanalysis. In addition, these compounds were evaluated for their in vitro antioxidant activity. Mechanisms of antioxidative activity were theoretically investigated by the density functional theory approach and the calculated values of various thermodynamic parameters, such as bond dissociation enthalpy, proton affinity, frontier molecular orbitals, and ionization potential. In silico calculations indicated that hydrogen atom transfer and sequential proton loss–electron transfer reaction mechanisms are probable, in non-polar and polar solvents respectively. Additionally, it was found that the single-electron transfer followed by proton transfer was not an operative mechanism in either solvent. The conducted tests indicate the excellent antioxidant activity, as well as the low potential toxicity, of the investigated compounds, which makes them good candidates for potential use in food chemistry.

scholarly journals Flavones’ and Flavonols’ Antiradical Structure–Activity Relationship—A Quantum Chemical Study

Antioxidants ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 461 ◽  
Author(s):  
Maciej Spiegel ◽  
Tadeusz Andruniów ◽  
Zbigniew Sroka
Keyword(s):  
Electron Transfer ◽  
Hydrogen Bonding ◽  
Density Functional ◽  
Hydrogen Abstraction ◽  
Quantum Chemical Study ◽  
Hydrogen Atom Transfer ◽  
Hydroxyl Group ◽  
Water Solvent ◽  
Intramolecular Hydrogen ◽  
Catechol Moiety

Flavonoids are known for their antiradical capacity, and this ability is strongly structure-dependent. In this research, the activity of flavones and flavonols in a water solvent was studied with the density functional theory methods. These included examination of flavonoids’ molecular and radical structures with natural bonding orbitals analysis, spin density analysis and frontier molecular orbitals theory. Calculations of determinants were performed: specific, for the three possible mechanisms of action—hydrogen atom transfer (HAT), electron transfer–proton transfer (ETPT) and sequential proton loss electron transfer (SPLET); and the unspecific—reorganization enthalpy (RE) and hydrogen abstraction enthalpy (HAE). Intramolecular hydrogen bonding, catechol moiety activity and the probability of electron density swap between rings were all established. Hydrogen bonding seems to be much more important than the conjugation effect, because some structures tends to form more intramolecular hydrogen bonds instead of being completely planar. The very first hydrogen abstraction mechanism in a water solvent is SPLET, and the most privileged abstraction site, indicated by HAE, can be associated with the C3 hydroxyl group of flavonols and C4’ hydroxyl group of flavones. For the catechol moiety, an intramolecular reorganization to an o-benzoquinone-like structure occurs, and the ETPT is favored as the second abstraction mechanism.

scholarly journals Structure-antioxidant Activity Relationships of Dendrocandin Analogues Determined Using Density Functional Theory

2021 ◽  
Author(s):  
Ning Zhang ◽  
Yilong Wu ◽  
Miao Qiao ◽  
Wenjuan Yuan ◽  
Xingyu Li ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Antioxidant Activity ◽  
Electron Transfer ◽  
Molecular Orbital ◽  
Density Functional ◽  
Antioxidant Properties ◽  
Hydrogen Atom Transfer ◽  
Antioxidant Compounds ◽  
Functional Theory ◽  
Chemical Structures

Abstract Quantum-chemical calculations based on the density functional theory (DFT) at the B3LYP/6–311++G(2d,2p)//B3LYP/6–31G(d,p) level were employed to study the relationship between the antioxidant properties and chemical structures of six dendrocandin (DDCD) analogues in the gas phase and two solvents (methanol and water). The hydrogen atom transfer (HAT), electron-transfer-proton-transfer (ET-PT), and sequential proton-loss-electron-transfer (SPLET) mechanisms are explored. The highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), reactivity indices (η, μ, ω, ω+, and ω–), and molecular electrostatic potentials (MEPs) were also evaluated. The results suggest that the D ring plays an important role in mediating the antioxidant activity of DDCDs. For all the studied compounds, indicating that HAT was identified as the most favorable mechanism, whereas the SPLET mechanism was the most thermodynamically favorable pathway in polar solvents. The results of our study should aid in the development of new or modified antioxidant compounds.

scholarly journals Biological Evaluation of 4-(1H-triazol-1-yl)benzoic Acid Hybrids as Antioxidant Agents: In Vitro Screening and DFT Study

2021 ◽  
Vol 11 (24) ◽  
pp. 11642
Author(s):  
Hatem A. Abuelizz ◽  
Hanan A. A. Taie ◽  
Ahmed H. Bakheit ◽  
Mohamed Marzouk ◽  
Mohamed M. Abdellatif ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Electron Transfer ◽  
Benzoic Acid ◽  
Antioxidant Properties ◽  
Biological Evaluation ◽  
Hydrogen Atom Transfer ◽  
Scavenging Activity ◽  
Antioxidant Agents ◽  
Power Capability

Fourteen triazole benzoic acid hybrids were previously characterized. This work aimed to screen their in vitro antioxidant activity using different assays, i.e., DPPH (1,1-diphenyl-1-picrylhydrazyl), reducing the power capability, FRAP (ferric reducing antioxidants power) and ABTS (2,2′-azino-bis(3-ethylben zothiazoline-6-sulfonate) radical scavenging. The 14 compounds showed antioxidant properties in relation to standard BHA (butylated hydroxylanisole) and Trolox (6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid). Higher antioxidant activity was observed by the parent (1) at a concentration of 100 µg/mL (89.95 ± 0.34 and 88.59 ± 0.13%) when tested by DPPH and ABTS methods in relation to BHA at 100 µg/mL (95.02 ± 0.74 and 96.18 ± 0.33%). The parent (2) demonstrated remarkable scavenging activity when tested by ABTS (62.00 ± 0.24%), however, 3 was less active (29.98 ± 0.13%). Compounds 5, 6, 9, and 11 exhibited good scavenging activity compared to 1. DFT studies were performed using the B3LYP/6-311++g (2d,2p) level of theory to evaluate different antioxidant descriptors for the targets. Three antioxidant mechanisms, i.e., hydrogen atom transfer (HAT), sequential electron transfer proton transfer (SETPT) and sequential proton loss electron transfer (SPLET) were suggested to describe the antioxidant properties of 1–14. Out of the 14 triazole benzoic acid hybrids, 5, 9, 6, and 11 showed some good theoretical results, which were in agreement with some experimental outcomes. Based on the computed (PA and ETE) and (BDE and IP) values in (SPLET) and (HAT and SETPT) mechanisms, respectively, compound 9 emerged has having good antioxidant activity.

scholarly journals SYNTHESIS, IN VITRO ANTIOXIDANT AND ANTIMICROBIAL EVALUATION OF 3-HYDROXY CHROMONE DERIVATIVES

2018 ◽  
Vol 11 (3) ◽  
pp. 259
Author(s):  
Pallavi Kamble ◽  
Sailesh Wadher
Keyword(s):  
Antioxidant Activity ◽  
Double Bond ◽  
Antifungal Activity ◽  
Phenolic Hydroxyl ◽  
Hydroxyl Group ◽  
Antibacterial And Antifungal Activity ◽  
Activity Data ◽  
Group 4 ◽  
Antibacterial And Antifungal

 Objective: The objective of the present study was to synthesize a series of 3-hydroxychromone derivatives and to evaluate its in vitro antioxidant and antimicrobial activities.Methods: 3-hydroxy chromones were synthesized using an algar flynn oyamada method which includes oxidative cyclization of 2-hydroxy chalcones in basic solution by hydrogen peroxide. 2-hydroxy chalcones were synthesized by Claisen-Schmidt condensation of substituted 2-hydroxy acetophenones with substituted aromatic aldehydes using polyethylene glycol-400 as a recyclable solvent. The synthesized compounds were evaluated for in vitro antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl radical scavenging assay. In addition, these compounds were also screened for in vitro antibacterial and antifungal activity by agar cup method and Poison plate method, respectively.Results: The structures of the synthesized compounds were characterized by infrared, 1H nuclear magnetic resonance and mass spectroscopy. The antioxidant activity data revealed that all the synthesized derivatives exhibited good activity due to the presence of phenolic hydroxyl group, 4-oxo group and 2,3-double bond. Further, the activity increased with the introduction of a more phenolic hydroxyl group and adjacent methoxy group in the structure. The antimicrobial activity data showed that the compounds possess better antibacterial and antifungal activity which is attributed to the presence of phenolic hydroxyl group and 4-oxo group in the structure.Conclusions: The use of inexpensive, eco-friendly and readily available reagents, easy work-up and high purity of products makes the procedure a convenient and robust method for the synthesis of title compounds. The presence of phenolic hydroxyl group, 4-oxo group, and 2,3-double bond in the structure is responsible for their good antioxidant and antimicrobial activities.

scholarly journals A Theoretical Study of the Adsorption Process of B-aflatoxins Using Pyracantha koidzumii (Hayata) Rehder Biomasses

Toxins ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 283
Author(s):  
Abraham Méndez-Albores ◽  
René Escobedo-González ◽  
Juan Manuel Aceves-Hernández ◽  
Perla García-Casillas ◽  
María Inés Nicolás-Vázquez ◽  
...  
Keyword(s):  
Functional Groups ◽  
Electrostatic Interactions ◽  
Density Functional ◽  
Ph Value ◽  
Theoretical Calculations ◽  
Basis Set ◽  
Hydroxyl Group ◽  
Biosorption Process

Employing theoretical calculations with density functional theory (DFT) using the B3LYP/6-311++G(d,p) functional and basis set, the interaction of the aflatoxin B1 (AFB1) molecule and the functional groups present in the Pyracantha koidzumii biosorbent was investigated. Dissociation free energy and acidity equilibrium constant values were obtained theoretically both in solution (water) and gas phases. Additionally, the molecular electrostatic potential for the protonated molecules was calculated to verify the reactivity. Thus, methanol (hydroxyl group), methylammonium ion (amino group), acetate ion (carboxyl group), and acetone (carbonyl group), were used as representatives of the substrates present in the biomass; these references were considered using the corresponding protonated or unprotonated forms at a pH value of 5. The experimental infrared spectrophotometric data suggested the participation of these functional groups in the AFB1 biosorption process, indicating that the mechanism was dominated by electrostatic interactions between the charged functional groups and the positively charged AFB1 molecule. The theoretical determination indicated that the carboxylate ion provided the highest interaction energy with the AFB1 molecule. Consequently, an enriched biosorbent with compounds containing carboxyl groups could improve the yield of the AFB1 adsorption when using in vitro and in vivo trials.

scholarly journals Theoretical investigations on the antioxidant potential of a non-phenolic compound thymoquinone: a DFT Approach

2021 ◽  
Author(s):  
Jewel Hossen ◽  
M. Abbas Ali ◽  
Sultanur Reza
Keyword(s):  
Antioxidant Activity ◽  
Free Radical ◽  
Density Functional ◽  
Nigella Sativa ◽  
Radical Scavenging ◽  
Hydroxyl Group ◽  
Black Cumin ◽  
Theoretical Investigations ◽  
Water Media ◽  
Thermochemical Parameters

Abstract Thymoquinone (TQ) is a natural compound occurred in black cumin ( Nigella sativa L.), which possesses potent antioxidant activity without having any phenolic hydroxyl group believed to be responsible for antioxidant activity of a molecule. In the present study, computational calculation based on Density Functional Theory (DFT) have been executed to assess systematically the worth of antioxidant behavior of this compound. Geometrical characteristics, HOMO-LUMO and MEP surface have been studied. Thermochemical parameters correlated to the leading antioxidant mechanisms such as HAT, SETPT and SPLET have been studied in gas and water media. In addition, the changes of thermochemical parameters such as ∆G and ∆H have been computed for HA from TQ to hydroxyl radical in gas and water phases to investigate its free radical scavenging potency. The low and comparable values of BDE, PDE, IP, PA and ETE suggest the antioxidant activity. The ∆G and ∆H also convey apposite thermodynamic evidence in favor of antiradical capability of TQ. The attack of the free radical takes place preferentially at 3CH position of the molecule.

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