scholarly journals Investigation of Reaction Mechanisms and Kinetics of the Radical Scavenging Ability of 5-Tert-Butylbenzene-1,2,3-Triol and 3,5-di-Tert-Butylbenzene-1,2-Diol Compounds Towards OOH Radical

2018 ◽  
Vol 43 (2) ◽  
pp. 101-111
Author(s):  
Anes El-Hadj Saïd ◽  
Sidi Mohamed Mekelleche
Keyword(s):  
Gas Phase ◽  
Density Functional ◽  
Radical Scavenging Activity ◽  
Antioxidant Properties ◽  
Radical Scavenging ◽  
Hydrogen Atom Transfer ◽  
System A ◽  
Radical Adduct ◽  
Scavenging Capacity ◽  
Radical Scavenging Ability

The antioxidant properties of the synthesised 5- tert-butylbenzene-1,2,3-triol (system A) and the designed 3,5-di -tert-butylbenzene-1,2-diol (system B) have been explored through density functional theory at the M05-2X/6-31+G(d,p) level of theory. The quantum mechanics-based test for overall free radical scavenging activity (QM- ORSA) protocol has been employed to account for their radical-scavenging capacity against the hydroperoxyl radical (HOO•) in the gas phase and in toluene solvent as a mimic lipid medium. The different mechanisms of the chemical reactions of the studied systems with HOO• have been considered, namely (i) the hydrogen atom transfer (HAT), (ii) the single electron transfer followed by proton transfer and (iii) the radical adduct formation. Our calculations provide evidence that HAT is the most favoured reaction mechanism in both the gas phase and in lipid media and the calculated thermodynamic and kinetic parameters indicate that the designed compound is more efficient than the synthesised system A and the reference system (α-tocopherol).

scholarly journals Antioxidant and UV-radiation absorption activity of aaptamine derivatives – Potential application for natural organic sunscreens

2021 ◽  
Author(s):  
Thi Le Anh Nguyen ◽  
Thi Hoai Nam Doan ◽  
Dinh Hieu Truong ◽  
Nguyen Thi Ai Nhung ◽  
Duong Tuan Quang ◽  
...  
Keyword(s):  
Density Functional ◽  
Antioxidant Activities ◽  
Radical Scavenging Activity ◽  
Antioxidant Properties ◽  
Radical Scavenging ◽  
Hydrogen Atom Transfer ◽  
Radiation Absorption ◽  
Chelating Activity ◽  
Radical Adduct ◽  
Potential Applications

Antioxidant and UV absorption activities of three marine product originated - aaptamine derivatives including piperidine[3,2-b]demethyl(oxy)aaptamine (<b>C1</b>), 9-amino-2-ethoxy-8-methoxy-3H-benzo[de][1,6]naphthyridine-3-one (<b>C2</b>), and 2-(sec-butyl)-7,8-dimethoxybenzo[de]imidazo[4,5,1-ij][1,6]-naphthyridin-10(9H)-one (<b>C3</b>) were theoretically studied by density functional theory (DFT). Direct antioxidant activities of C1–C3 were firstly evaluated via their intrinsic thermochemical properties and radical scavenging activity of the potential antioxidants with the HOO●/HO● radicals via four mechanisms, including: hydrogen atom transfer (HAT), single electron transfer (SET), proton loss (PL) and radical adduct formation (RAF). Kinetic calculation reveals that HOO● scavenging in water is occurred via HAT mechanism with C1 (kapp, 7.13x10<sup>6</sup> M-1 s-1) while RAF is more dominant with C2 (k<sub>app</sub>, 1.40x10<sup>5</sup> M-1 s-1) and C3 (kapp, 2.90x10<sup>5</sup> M-1 s-1). Antioxidant activity of aaptamine derivatives can be classified as <b>C1 </b>> <b>C3 </b>> <b>C2</b>. Indirect antioxidant properties based on Cu(I) and Cu(II) ions chelating activity were also investigated in aqueous phase. All three studied compounds show spontaneous and favorable Cu(I) ion chelating activity with DG0 being -15.4, -13.7, and -15.7 kcal.mol-1, whereas DG0 for Cu(II) chelation are -10.4, -10.8, and -2.2 kcal.mol-1 for C1, C2 and C3, respectively. In addition, all compounds show UVA and UVB absorption; in which the excitations are determined mostly as π-π* transition. Overall, the results suggest the potential applications of the aaptamines in pharmaceutics and cosmetics, i.e. as sunscreen and antioxidant ingredient.<br>

scholarly journals Radical-Scavenging and UV-Radiation Absorption Activities of Aaptamine Derivatives: DFT and TD-DFT Studies

2021 ◽  
Author(s):  
Thi Hoai Nam Doan ◽  
Thi Le Anh Nguyen ◽  
Nguyen Thi Ai Nhung ◽  
Duong Tuan Quang ◽  
Duy Quang Dao
Keyword(s):  
Density Functional ◽  
Antioxidant Activities ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Hydrogen Atom Transfer ◽  
Radiation Absorption ◽  
Functional Theory ◽  
Radical Adduct ◽  
Td Dft ◽  
Potential Applications

Antioxidant and UV absorption activities of three aaptamine derivatives including piperidine[3,2-b]demethyl(oxy)aaptamine (C1), 9-amino-2-ethoxy-8-methoxy-3H-benzo[de][1,6]naphthyridine-3-one (C2), and 2-(sec-butyl)-7,8-dimethoxybenzo[de]imidazo[4,5,1-ij][1,6]-naphthyridin-10(9H)-one (C3) were theoretically studied by density functional theory (DFT). Optimized geometries of C1C3 and theirs intrinsic thermochemical properties such as bond dissociation energy, proton affinity, and ionization potential were calculated at DFT/M05-2X/6-311++G(d,p) level of theory in vacuo and in water. The results show that C1C3 exhibited similar potent antioxidant activities, which are comparable to well-known antioxidants such as Trolox or cembrene. The radical scavenging activity of the antioxidants were then investigated by evaluation the Gibbs free energy (ΔrG0) of the reaction between C1C3 and the HOO●/HO● radicals via four mechanisms, including: hydrogen atom transfer (HAT), single electron transfer (SET), proton loss (PL) and radical adduct formation (RAF). Kinetic calculation reveals that HOO● scavenging in water is occurred via HAT mechanism with C1@C19 while RAF is more dominant with C2 and C3. Antioxidant activity of aaptamine derivatives can be classified as C1 > C3 > C2. In addition, all compounds are active in UV-Vis absorption; the excitations of which are determined as π-π* transition. Overall, the results suggest the potential applications of the aaptamines in pharmaceutics and cosmetics, i.e. as sunscreen and antioxidant ingredient<br>

THERMODYNAMICS OF THE ANTIOXIDANT ACTIVITY OF HUMULONES AND OTHER ANTIOXIDANTS FROM BEER – A MOLECULAR MODELING APPROACH

2021 ◽  
Author(s):  
Ilija Cvijetić ◽  
◽  
Miljan Bigović ◽  
Petar Ristivojević ◽  
Maja Vitorović-Todorović ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Free Radicals ◽  
Gas Phase ◽  
Density Functional ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Hydrogen Atom Transfer ◽  
Structural Basis ◽  
Recent Experimental Study ◽  
Cis And Trans

Recent experimental study identified eight potent antioxidants in German beers, including isoxanthohumol, (R)- and (S)-adhumulone, cis– and trans-iso-adhumulone, cis– and trans-iso- n-humulone, and desdimetyhyl-octahydro-iso-cohumulone. To provide insights into the structural basis of their radical scavenging activity, we calculated the thermodynamic feasibility of two common antioxidant mechanisms, hydrogen atom transfer (HAT) and single electron transfer followed by proton transfer (SET-PT), using the density functional theory (DFT) with B3LYP/6-311g++(2d,2p) method in the gas phase and implicit solvation model of water. The calculated bond dissociation enthalpies (BDEs) and ionization potential (IP) of all compounds were compared with the corresponding values for resveratrol, a highly potent antioxidant found in red wine. The fully reduced humulone isomer, desdimetyhyl-octahydro-iso-cohumulone, could scavenge free radicals via HAT as revealed by BDEs 5.1 and 23.9 kJ/mol lower than the values for resveratrol in gas phase and water, respectively. Furthermore, the enolic –OH group was identified as the pharmacophoric hotspot for the interaction of humulones with the reactive free radicals. The HAT potency of this group is significantly reduced through the formation of strong intramolecular hydrogen bond (IHB) with the β-keto group. Moreover, the SET-PT mechanism was thermodynamically favorable for isoxanthohumol. These results strongly suggest higher antioxidant activity of beers with the increased content of the reduced forms of humulones and their isomers.

scholarly journals Antioxidant Properties of Camphene-Based Thiosemicarbazones: Experimental and Theoretical Evaluation

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1192
Author(s):  
Lijuan Yang ◽  
Haochuang Liu ◽  
Dasha Xia ◽  
Shifa Wang
Keyword(s):  
Density Functional ◽  
Peroxyl Radical ◽  
Biological Activities ◽  
Radical Scavenging Activity ◽  
Antioxidant Properties ◽  
Radical Scavenging ◽  
Theoretical Data ◽  
Hydrogen Atom Transfer ◽  
Theoretical Evaluation ◽  
Wide Range

The thiosemicarbazone derivatives have a wide range of biological activities, such as antioxidant activity. In this study, the antiradical activities of six camphene-based thiosemicarbazones (TSC-1~6) were investigated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and peroxyl radical scavenging capacity (PSC) assays, respectively, and the results reveal that TSC1~6 exhibited good abilities for scavenging free radicals in a dose-dependent way. Compound TSC-2 exhibited the best effect of scavenging DPPH radical, with the lowest EC50 (0.208 ± 0.004 mol/mol DPPH) as well as the highest bimolecular rate constant Kb (4218 M−1 s−1), which is 1.18-fold higher than that of Trolox. Meanwhile, TSC-2 also obtained the lowest EC50 (1.27 µmol of Trolox equiv/µmol) of scavenging peroxyl radical. Furthermore, the density functional theory (DFT) calculation was carried out to further explain the experimental results by calculating several molecular descriptors associated with radical scavenging activity. These theoretical data suggested that the electron-donating effect of the diethylamino group in TSC-2 leads to the enhancement of the scavenging activities and the studied compounds may prefer to undergo the hydrogen atom transfer process.

scholarly journals Radical Scavenging Activity of Puerarin: A Theoretical Study

Antioxidants ◽  
2019 ◽  
Vol 8 (12) ◽  
pp. 590 ◽  
Author(s):  
Huakang Zhou ◽  
Xiangzhou Li ◽  
Yaxuan Shang ◽  
Kai Chen
Keyword(s):  
Electron Transfer ◽  
Density Functional ◽  
Theoretical Study ◽  
Wide Spectrum ◽  
Radical Scavenging Activity ◽  
Antioxidant Properties ◽  
Radical Scavenging ◽  
Hydrogen Atom Transfer ◽  
Scavenging Activity ◽  
Dissociation Enthalpy

Puerarin is a C-glycoside of daidzein, one of the major bioactive ingredients isolated from the root of Pueraria lobata, which has a wide spectrum of pharmacological effects. Although puerarin is well-known for its effective antioxidant activity, there is seldom a systematic theoretical study on its radical scavenging activity. Herein, the free radical scavenging ability of puerarin was investigated systematically by density functional theory (DFT) calculations. The reaction activity was compared with daidzein as well. Three reaction pathways: hydrogen atom transfer (HAT), single electron transfer followed by proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET) were discussed and compared by thermodynamic parameters such as bond dissociation enthalpy (BDE), ionization potential (IP), proton dissociation enthalpy (PDE), proton affinity (PA), and electron transfer enthalpy (ETE). The reaction kinetics of puerarin with special radicals •OH and •OOH were also studied. The results obtained may be of great significance for better understanding the relationship between the antioxidant properties and structural design of puerarin, as well as other antioxidants.

scholarly journals Radical-Scavenging and UV-Radiation Absorption Activities of Aaptamine Derivatives: DFT and TD-DFT Studies

2021 ◽  
Author(s):  
Thi Hoai Nam Doan ◽  
Thi Le Anh Nguyen ◽  
Nguyen Thi Ai Nhung ◽  
Duong Tuan Quang ◽  
Duy Quang Dao
Keyword(s):  
Density Functional ◽  
Antioxidant Activities ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Hydrogen Atom Transfer ◽  
Radiation Absorption ◽  
Functional Theory ◽  
Radical Adduct ◽  
Td Dft ◽  
Potential Applications

Antioxidant and UV absorption activities of three aaptamine derivatives including piperidine[3,2-b]demethyl(oxy)aaptamine (C1), 9-amino-2-ethoxy-8-methoxy-3H-benzo[de][1,6]naphthyridine-3-one (C2), and 2-(sec-butyl)-7,8-dimethoxybenzo[de]imidazo[4,5,1-ij][1,6]-naphthyridin-10(9H)-one (C3) were theoretically studied by density functional theory (DFT). Optimized geometries of C1C3 and theirs intrinsic thermochemical properties such as bond dissociation energy, proton affinity, and ionization potential were calculated at DFT/M05-2X/6-311++G(d,p) level of theory in vacuo and in water. The results show that C1C3 exhibited similar potent antioxidant activities, which are comparable to well-known antioxidants such as Trolox or cembrene. The radical scavenging activity of the antioxidants were then investigated by evaluation the Gibbs free energy (ΔrG0) of the reaction between C1C3 and the HOO●/HO● radicals via four mechanisms, including: hydrogen atom transfer (HAT), single electron transfer (SET), proton loss (PL) and radical adduct formation (RAF). Kinetic calculation reveals that HOO● scavenging in water is occurred via HAT mechanism with C1@C19 while RAF is more dominant with C2 and C3. Antioxidant activity of aaptamine derivatives can be classified as C1 > C3 > C2. In addition, all compounds are active in UV-Vis absorption; the excitations of which are determined as π-π* transition. Overall, the results suggest the potential applications of the aaptamines in pharmaceutics and cosmetics, i.e. as sunscreen and antioxidant ingredient<br>

Peripherally substituted soluble nickel phthalocyanines: Synthesis, characterization, aggregation behavior and antioxidant properties

2019 ◽  
Vol 23 (11n12) ◽  
pp. 1478-1485
Author(s):  
Senem Çolak Yazıcı ◽  
Sibel Kahraman ◽  
Salih Z. Yıldız ◽  
Mahmut D. Yılmaz
Keyword(s):  
Sulfonic Acid ◽  
Antioxidant Activities ◽  
Radical Scavenging Activity ◽  
Antioxidant Properties ◽  
Radical Scavenging ◽  
Scavenging Activity ◽  
The Novel ◽  
Diammonium Salt ◽  
Ft Ir ◽  
Radical Scavenging Ability

Tetra-zwitterionic-substituted nickel(II) phthalocyanine derivatives were newly synthesized starting from nonionic 2(3),9(10),16(17),23(24)-tetrakis-[2-([Formula: see text]-((3-dimethylamino)propyl)carbamate)oxyethyl)phthalocyaninato nickel (II). The novel compounds have been characterized by a combination of UV-vis, FT-IR and mass spectroscopies and elemental analysis. The critical micelle concentrations of the prepared compounds were measured, and the antioxidant activities were analyzed with radical scavenging ability of 1,1-diphenyl-2-picrylhydrazyl (DPPH) and with 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS). The zwitterionic molecules showed aggregated spectra in the UV-vis region, and they might be good surfactant candidates for the detergent industry with their appropriate critical micelle concentration (CMC) properties in water. The compounds exhibited ABTS radical scavenging activity and thus they have antioxidant activity.

scholarly journals DFT Studies on the Antioxidant Activity of Naringenin and Its Derivatives: Effects of the Substituents at C3

2019 ◽  
Vol 20 (6) ◽  
pp. 1450 ◽  
Author(s):  
Yan-Zhen Zheng ◽  
Geng Deng ◽  
Rui Guo ◽  
Da-Fu Chen ◽  
Zhong-Min Fu
Keyword(s):  
Antioxidant Activity ◽  
Density Functional ◽  
Radical Scavenging Activity ◽  
Resonance Effect ◽  
Antioxidant Properties ◽  
Radical Scavenging ◽  
Dft Method ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Selection Of

The radical scavenging activity of a flavonoid is largely influenced by its structure. The effects of the substituents at C3 position on the antioxidant activity of naringenin were carried out using the density functional theory (DFT) method. The reaction enthalpies related with the three well-established mechanisms were analyzed. Excellent correlations were found between the reaction enthalpies and Hammett sigma constants. Equations obtained from the linear regression can be helpful in the selection of suitable candidates for the synthesis of novel naringenin derivatives with enhanced antioxidant properties. In the gas and benzene phases, the antioxidant activity of naringenin was enhanced by the electron-donating substituents via weakening the bond dissociation enthalpy (BDE). In the water phase, it was strengthened by electron-withdrawing groups—via lowering the proton affinity (PA). The electronic effect of the substituent on the BDE of naringenin is mainly governed by the resonance effect, while that on the ionization potential (IP) and PA of naringenin is mainly controlled by the field/inductive effect.

Density Functional Theory Calculations of the Radical Scavenging Activity of Alkannin Derivatives

2012 ◽  
Vol 189 ◽  
pp. 225-231
Author(s):  
Xiang Peng Guo ◽  
Rui Fa Jin
Keyword(s):  
Density Functional ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Density Functional Theory Calculations ◽  
Hydrogen Atom Transfer ◽  
Scavenging Activity ◽  
Functional Theory ◽  
Hydrogen Bond Formation ◽  
Structural And Electronic Properties ◽  
The One

The structural and electronic properties of alkannin and its derivatives and their radicals were investigated at density functional level. It turned out that the presence of the dihydroxy functionality increases the radical stability through hydrogen bond formation. The hydrogen atom transfer for alkannin derivatives is difficult to occur compared with zero compound phenol. However, alkannin derivatives appear to be good candidates for the one-electron-transfer, particularly for alkannin derivatives with –OCOCH=CH(CH3)2 and –OCOCH2CH(CH3)2 groups. It suggests that 1–7 are expected to be the promising candidates for radical scavenging activity compounds because The ionization potential (IP) values of 1–7 are lower than that of the zero compound phenol.

scholarly journals Radical Scavenging Activity and Pharmacokinetic Properties of Coumarin–Hydroxybenzohydrazide Hybrids

2022 ◽  
Vol 23 (1) ◽  
pp. 490
Author(s):  
Marko R. Antonijević ◽  
Edina H. Avdović ◽  
Dušica M. Simijonović ◽  
Žiko B. Milanović ◽  
Ana D. Amić ◽  
...  
Keyword(s):  
Spin State ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Hydrogen Atom Transfer ◽  
Skin Permeability ◽  
Scavenging Activity ◽  
Coumarin Derivatives ◽  
Pharmacokinetic Properties ◽  
Low Toxicity ◽  
Radical Scavenging Ability

Free radicals often interact with vital proteins, violating their structure and inhibiting their activity. In previous studies, synthesis, characterisation, and the antioxidative properties of the five different coumarin derivatives have been investigated. In the tests of potential toxicity, all compounds exhibited low toxicity with significant antioxidative potential at the same time. In this paper, the radical scavenging activity of the abovementioned coumarin derivatives towards ten different radical species was investigated. It was found that all investigated compounds show good radical scavenging ability, with results that are in correlation with the results published in the previous study. Three additional mechanisms of radical scavenging activity were investigated. It was found that all three mechanisms are thermodynamically plausible and in competition. Interestingly, it was found that products of the Double Hydrogen Atom Transfer (DHAT) mechanism, a biradical species in triplet spin state, are in some cases more stable than singlet spin state analogues. This unexpected trend can be explained by spin delocalisation over the hydrazide bridge and phenolic part of the molecule with a low probability of spin pairing. Besides radical-scavenging activity, the pharmacokinetic and drug-likeness of the coumarin hybrids were investigated. It was found that they exhibit good membrane and skin permeability and potential interactions with P-450 enzymes. Furthermore, it was found that investigated compounds satisfy all criteria of the drug-likeness tests, suggesting they possess a good preference for being used as potential drugs.

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