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.

DFT study of free radical scavenging activity of erodiol

2013 ◽  
Vol 67 (11) ◽  
Author(s):  
Zoran Marković ◽  
Jelena Đorović ◽  
Milan Dekić ◽  
Milanka Radulović ◽  
Svetlana Marković ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Hydrogen Atom Transfer ◽  
Free Radical Scavenging ◽  
Single Electron Transfer ◽  
Transfer Energy ◽  
Dissociation Enthalpy ◽  
Proton Dissociation ◽  
Transfer Mechanisms

AbstractAntioxidant activity of erodiol was examined at the M05-2X/6-311+G(d,p) level of theory in the gas and aqueous phases. The structure and energy of radicals and anions of the most stable erodiol rotamer were analyzed. To estimate antioxidant potential of erodiol, different molecular properties were examined: bond dissociation enthalpy, proton affinity together with electron transfer energy, and ionization potential followed by proton dissociation enthalpy. It was found that hydrogen atom transfer is the prevailing mechanism of erodiol behavior in gas; whereas single electron transfer followed by proton transfer and sequential proton loss electron transfer mechanisms represent the thermodynamically preferred reaction paths in water.

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.

DFT Study of Structure and Radical Scavenging Activity of Natural Pigment Delphinidin and Derivatives

2021 ◽  
Author(s):  
Sumayya Pottachola ◽  
Arifa Kaniyantavida ◽  
Muraleedharan Karuvanthodiyil
Keyword(s):  
Antioxidant Activity ◽  
Electron Transfer ◽  
Gas Phase ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Scavenging Activity ◽  
Natural Pigment ◽  
Physiochemical Parameters ◽  
Dissociation Enthalpy ◽  
Spin Density Calculation

A theoretical evaluation of the antioxidant activity of natural pigment delphinidin (1a) and derivatives 1b, 1c, 1d & 1e was performed using the DFT-B3LYP/6–311 + G (d, p) level of theory. Three potential working mechanisms, hydrogen atom transfer (HAT), stepwise electron transfer proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET), have been investigated. The physiochemical parameters, including O–H bond dissociation enthalpy (BDE), ionization potential (IP), proton dissociation enthalpy (PDE), proton affinity (PA), and electron transfer enthalpy (ETE), have been calculated in the gas phase and aqueous phase. The study found that the most suitable mechanism for explaining antioxidant activity is HAT in the gas phase and SPLET in the aqueous medium in this level of theory. Spin density calculation and delocalization index of studied molecules also support the radical scavenging activity. When incorporated into natural pigment delphinidin, the gallate moiety can enhance the activity and stability of the compounds.

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 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 Substituent Effects on the Radical Scavenging Activity of Isoflavonoid

2019 ◽  
Vol 20 (2) ◽  
pp. 397 ◽  
Author(s):  
Yan-Zhen Zheng ◽  
Geng Deng ◽  
Rui Guo ◽  
Da-Fu Chen ◽  
Zhong-Min Fu
Keyword(s):  
Electron Transfer ◽  
Density Functional ◽  
Antioxidative Activity ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Substituent Effects ◽  
Hydrogen Atom Transfer ◽  
Electronic Effects ◽  
Antioxidative Properties ◽  
Electronic Effects Of Substituents

Understanding the role of substituents is of great importance for the preparation of novel phenolic compounds with enhanced antioxidative properties. In this work, the antioxidative activity of isoflavonoid derivatives with different substituents placed at the C2 position was determined by density functional theory (DFT) calculations. The bond dissociation enthalpy (BDE), ionization potential (IP), and proton affinity (PA) related to hydrogen atom transfer (HAT), single electron transfer-proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET) mechanisms were calculated. The strongest antioxidative group of isoflavonoid is not altered by the substituents. Excellent correlations were found between the BDE/IP/PA and Hammett sigma constants. Equations obtained from linear regression can be useful in the selection of suitable candidates for the synthesis of novel isoflavonoids derivatives with enhanced antioxidative properties. In the gas and benzene phases, the electron-donating substituents would enhance the antioxidative activity of isoflavonoids via weakening the BDE of 4′−OH. In water phase, they will reduce the antioxidative by strengthening the PA of 7−OH. Contrary results occur for the electron-withdrawing groups. In addition, the electronic effects of substituents on the BDE/IP/PA have also been analyzed.

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).

Radical scavenging activity of hydroxycinnamic acids in polar and nonpolar solvents: A computational investigation

2020 ◽  
Vol 19 (08) ◽  
pp. 2050032
Author(s):  
Hadjer Mansouri ◽  
Sidi Mohamed Mekelleche
Keyword(s):  
Electron Transfer ◽  
Computational Study ◽  
Reaction Pathway ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Hydrogen Atom Transfer ◽  
Hydroxycinnamic Acids ◽  
Scavenging Activity ◽  
Strong Electron ◽  
Nonpolar Solvents

The aim of this work is to perform a computational study of the radical scavenging activity of a series of common hydroxycinnamic acids (HCAs) in polar and nonpolar solvents in order to rationalize the experimental order obtained in ethanol and to analyze the solvent effect on mechanism and radical scavenging capacity. The thermodynamics of the main mechanisms, namely, hydrogen atom transfer (HAT), sequential proton loss followed by electron transfer (SPLET), and single electron transfer followed by proton transfer (SET-PT) were investigated at the M05-2X/6-31[Formula: see text]G([Formula: see text]) level of theory using the SMD solvation model. This study shows that the SET-PT mechanism is disfavored in all media, whereas HAT is the most thermodynamically favored mechanism in gas phase and SPLET is the preferred reaction pathway in pentyl ethanoate, ethanol and water. The thermodynamically preferred site of antioxidant action and the radical scavenging order are predicted using the BDE[Formula: see text] and (PA[Formula: see text]ETE)[Formula: see text] descriptors corresponding to the HAT and SPLET mechanisms, respectively. The obtained results point out that the mechanism and the radical scavenging potency are influenced by solvent polarity and our predictions are in agreement with the experimental measurements performed in ethanol giving the following descending order: caffeic [Formula: see text] [Formula: see text] [Formula: see text]-coumaric acid. Our results also show that the ortho substitution of caffeic acid by strong electron donating groups leads to a notable increase of their radical scavenging activity and new potent HCA derivatives are designed.

scholarly journals Strobilanthes heyneanus root extract as a potential source for antioxidant and antimicrobial activity

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Vijayakumar Sundaram ◽  
Selvaraju Sadhasivam ◽  
Sivaraj Chandrasekaran ◽  
Raaman Nanjian ◽  
Arjun Pandian
Keyword(s):  
Dermal Fibroblast ◽  
Radical Scavenging Activity ◽  
Antioxidant Properties ◽  
Radical Scavenging ◽  
Reducing Power ◽  
Fibroblast Cell ◽  
Phytochemical Analysis ◽  
Root Extract ◽  
Scavenging Activity ◽  
Medicinal Uses

Abstract Background Strobilanthes heyneanus (Nilgirianthus heyneanus) belongs to the family Acanthaceae that contains many species with potential for diverse medicinal uses. It is also called ‘Karun kurinji’ and is commonly found in the South-West regions of India. The species are commonly used in rheumatic complaints, sprain of the ankle, and hernia. The objectives of the study were to evaluate the antioxidant activity, phytochemical analysis, and antibacterial activities of the root extract of S. heyneanus. Results The radical scavenging and reduction assays such as DPPH● radical and OH● radical scavenging assays, as well as phosphomolybdenum reduction and Fe3+ reducing power assays, were determined for the root extract. The highest DPPH● radical scavenging activity was 88.23 ± 1.32 at 120 μg/mL concentration, and the calculated IC50 was 38.52 μg/mL concentration. The highest OH● radical scavenging activity was 51.28 ± 1.06 at 120 μg/mL concentration, and the calculated IC50 was 51.28 μg/mL concentration. The highest ABTS●+ radical scavenging activity was 91.28 ± 1.12 at 30 μg/mL concentration, and the calculated IC50 was 33.92 μg/mL concentration. The highest phosphomolybdenum reduction was 87.43 ± 0.90 at 120 μg/mL concentration, and the calculated RC50 was 24.74 μg/mL concentration. The highest Fe3+ reduction was 89.38 ± 0.98 at 120 μg/mL concentration, and the calculated RC50 was 31.06 μg/mL concentration. The antibacterial activity of S. heyneanus showed the highest zone of inhibition of 24 mm for Salmonella typhi with 500 μg/mL concentration. The cytotoxicity limits of the root extracts were tested by MTT assay using human dermal fibroblast cell lines, reflecting > 90% cell viability at a concentration of 500 μg/mL. Conclusions The current study showed that the root extract of S. heyneanus has better antioxidant properties and potential anti-bacterial compounds. The phytochemical analysis of the root extract showed the presence of alkaloids, steroids, terpenoids, phenols, flavonoids, tannins, saponins, glycosides, and carbohydrates, which are responsible for the antibacterial root extract of S. heyneanus synergistically.

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