scholarly journals Defining a standardized methodology for the determination of the antioxidant capacity: case study of Pistacia atlantica leaves

The Analyst ◽  
2020 ◽  
Vol 145 (2) ◽  
pp. 557-571 ◽  
Author(s):  
Ziyad Ben Ahmed ◽  
Yousfi Mohamed ◽  
Viaene Johan ◽  
Bieke Dejaegher ◽  
Kristiaan Demeyer ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Electron Transfer ◽  
Hydrogen Atom ◽  
Antioxidant Capacity ◽  
Hydrogen Atom Transfer ◽  
Single Electron ◽  
Single Electron Transfer ◽  
Pistacia Atlantica

Antioxidant activity can be measured by a variety of methods, that include hydrogen atom transfer (HAT) and single electron transfer (ET) methods.

scholarly journals Regio- and chemoselective Csp3–H arylation of benzylamines by single electron transfer/hydrogen atom transfer synergistic catalysis

2018 ◽  
Vol 9 (44) ◽  
pp. 8453-8460 ◽  
Author(s):  
Takafumi Ide ◽  
Joshua P. Barham ◽  
Masashi Fujita ◽  
Yuji Kawato ◽  
Hiromichi Egami ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Hydrogen Atom ◽  
Hydrogen Atom Transfer ◽  
Single Electron ◽  
Atom Transfer ◽  
Single Electron Transfer ◽  
Synergistic Catalysis

Catalyst controlled regio-, and chemo-selective C-H arylation of benzylamines.

scholarly journals Cytochrome P450-catalyzed dealkylation of atrazine byRhodococcussp. strain NI86/21 involves hydrogen atom transfer rather than single electron transfer

2014 ◽  
Vol 43 (32) ◽  
pp. 12175-12186 ◽  
Author(s):  
Armin H. Meyer ◽  
Agnieszka Dybala-Defratyka ◽  
Peter J. Alaimo ◽  
Inacrist Geronimo ◽  
Ariana D. Sanchez ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Cytochrome P450 ◽  
Hydrogen Atom ◽  
Isotope Effects ◽  
Hydrogen Atom Transfer ◽  
Single Electron ◽  
Atom Transfer ◽  
Single Electron Transfer ◽  
Position Specificity

Isotope effects and position-specificity of hydroxylation pinpoint hydrogen atom transfer (HAT) as prevailing mechanism in P450 catalyzed N-dealkylation of atrazine.

Nature of transients produced on hydrogen atom transfer from capsaicin

2018 ◽  
Vol 17 (05) ◽  
pp. 1850036
Author(s):  
Ravi Joshi
Keyword(s):  
Electron Transfer ◽  
Hydrogen Atom ◽  
Dissociation Energy ◽  
Density Functional ◽  
Hydrogen Atom Transfer ◽  
Single Electron ◽  
Basis Set ◽  
Atom Transfer ◽  
Field Calculation ◽  
Single Electron Transfer

Structure and energies of capsaicin and its probable transients formed in oxidation processes (single electron transfer and hydrogen atom transfer) have been investigated using theoretical calculations. Molecular geometries and energies of truncated and complete capsaicin structures have been optimized using density functional theory (DFT) with Becke three-parameter Lee-Yang-Parr (B3LYP) functional and 6–31[Formula: see text]G(d) basis set. The stable geometries have been confirmed by vibrational analysis. The calculations suggest that single-electron transfer takes place at phenolic O-atom in the first step followed by delocalization of positive charge over the whole molecule. Further, the first step of hydrogen atom abstraction should take place at phenolic group due to lowest dissociation energy but post-optimization bond dissociation energy is least for benzylic group in the side chain as compared to other transients. Effect of water as a solvent on the energies has also been studied using self-consistent reaction field calculation. Similar results are obtained for truncated and complete capsaicin structures. The present study also includes Mulliken spin, charge, vibrational frequencies and assignments of frequencies of the transients. The present study provides explanation for the observation of phenoxyl radical in fast kinetic studies using pulse radiolysis study and, formation of breakdown and dimeric products in other studies.

Transition-Metal-Free C(sp3)–H Coupling of Cycloalkanes Enabled by Single-Electron Transfer and Hydrogen Atom Transfer

2021 ◽  
Vol 23 (5) ◽  
pp. 1714-1719
Author(s):  
Linlin Zhang ◽  
Zhengfen Liu ◽  
Xun Tian ◽  
Yujin Zi ◽  
Shengzu Duan ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Hydrogen Atom ◽  
Transition Metal ◽  
Hydrogen Atom Transfer ◽  
Single Electron ◽  
Atom Transfer ◽  
Single Electron Transfer ◽  
Metal Free

scholarly journals Radical Biocatalysis: Using Non-Natural Single Electron Transfer Mechanisms to Access New Enzymatic Functions

Synlett ◽  
2019 ◽  
Vol 31 (03) ◽  
pp. 248-254 ◽  
Author(s):  
Todd K. Hyster
Keyword(s):  
Electron Transfer ◽  
Active Sites ◽  
Hydrogen Atom Transfer ◽  
Single Electron ◽  
Great Promise ◽  
Single Electron Transfer ◽  
Radical Intermediates ◽  
Redox Activation ◽  
Transfer Mechanisms ◽  
Ground State Electron

Exploiting non-natural reaction mechanisms within native enzymes is an emerging strategy for expanding the synthetic capabilities of biocatalysts. When coupled with modern protein engineering techniques, this approach holds great promise for biocatalysis to address long-standing selectivity and reactivity challenges in chemical synthesis. Controlling the stereochemical outcome of reactions involving radical intermediates, for instance, could benefit from biocatalytic solutions because these reactions are often difficult to control by using existing small molecule catalysts. General strategies for catalyzing non-natural radical reactions within enzyme active sites are, however, undeveloped. In this account, we highlight three distinct strategies developed in our group that exploit non-natural single electron transfer mechanisms to unveil previously unknown radical biocatalytic functions. These strategies allow common oxidoreductases to be used to address the enduring synthetic challenge of asymmetric hydrogen atom transfer.1 Introduction2 Photoinduced Electron Transfer from NADPH3 Ground State Electron Transfer from Flavin Hydroquinone4 Enzymatic Redox Activation in NADPH-Dependent Oxidoreductases5 Conclusion

scholarly journals COMPARATIVE ANTIRADICAL ACTIVITY AND MOLECULAR DOCKING STUDY OF BERGAPTOL AND XANTHOTOXOL

2020 ◽  
pp. 71-84
Author(s):  
Žiko Milanović ◽  
Marko Antonijević ◽  
Jelena Đorović ◽  
Dejan Milenković
Keyword(s):  
Antioxidant Activity ◽  
Electron Transfer ◽  
Molecular Docking ◽  
Free Radical ◽  
Hydrogen Atom ◽  
Antiradical Activity ◽  
Docking Study ◽  
Hydrogen Atom Transfer ◽  
Molecular Docking Study ◽  
Anionic Species

The antioxidant activity of bergaptol (4-hydroxyfuro[3,2-g]chromen-7-one, BER) and xanthotoxol (9-hydroxyfuro[3,2-g]chromen-7-one, XAN) was investigated in water and benzene, as solvents. For this purpose, the density functional theory (DFT) was used. The free radical scavenging potency of investigated compounds towards different reactive oxygen species (ROS) was performed. Antioxidative mechanism of investigated compounds – hydrogen atom transfer (HAT), single-electron transfer–proton transfer (SET-PT) and sequential proton loss electron transfer (SPLET) were examined using M06-2X/6-311++G(d,p) theoretical model. The important thermodynamic parameters (BDE, IP, PDE, PA, ETE) and Gibbs free energies of reactions, were used to determine the most probable antioxidant mechanism of action. The obtained thermodynamic parameters suggested that Hydrogen Atom Transfer (HAT) is the most probable reaction pathway in benzene, while Sequential Proton Loss Electron Transfer (SPLET) was favorized in water. The obtained results indicate that the favorable mechanism of antiradical activity depends on the polarity of medium and the nature of free radical species. By comparing the antioxidant activity of investigated compounds, it can be concluded that bergaptol exhibits better antioxidant properties. Molecular docking study of neutral and anionic species of investigated compounds was performed according to Estrogen receptor alpha (ERα). In both cases, bergaptol showed better inhibitory potency. All the anionic species showed a higher inhibition constant, indicating lower inhibition potency than corresponding parent molecules.

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