Chain-breaking phenolic antioxidants: steric and electronic effects in polyalkylchromanols, tocopherol analogs, hydroquinones, and superior antioxidants of the polyalkylbenzochromanol and naphthofuran class

1993 ◽  
Vol 58 (26) ◽  
pp. 7416-7420 ◽  
Author(s):  
L. R. C. Barclay ◽  
M. R. Vinqvist ◽  
K. Mukai ◽  
S. Itoh ◽  
H. Morimoto
Keyword(s):  
Phenolic Antioxidants ◽  
Electronic Effects ◽  
Chain Breaking

scholarly journals Electronic and Hydrogen Bonding Effects on the Chain-Breaking Activity of Sulfur-Containing Phenolic Antioxidants

2006 ◽  
Vol 71 (17) ◽  
pp. 6325-6332 ◽  
Author(s):  
Riccardo Amorati ◽  
Maria Grazia Fumo ◽  
Stefano Menichetti ◽  
Veronica Mugnaini ◽  
Gian Franco Pedulli
Keyword(s):  
Hydrogen Bonding ◽  
Phenolic Antioxidants ◽  
Chain Breaking ◽  
Sulfur Containing

scholarly journals Computational Study of Ortho-Substituent Effects on Antioxidant Activities of Phenolic Dendritic Antioxidants

Antioxidants ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 189 ◽  
Author(s):  
Choon Young Lee ◽  
Ajit Sharma ◽  
Julius Semenya ◽  
Charles Anamoah ◽  
Kelli N. Chapman ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Electron Transfer ◽  
Antioxidant Activities ◽  
Computational Study ◽  
Radical Scavenging ◽  
Substituent Effects ◽  
Phenolic Antioxidants ◽  
Electronic Effects ◽  
Total Enthalpy ◽  
Structure Activity

Antioxidants are an important component of our ability to combat free radicals, an excess of which leads to oxidative stress that is related to aging and numerous human diseases. Oxidative damage also shortens the shelf-life of foods and other commodities. Understanding the structure–activity relationship of antioxidants and their mechanisms of action is important for designing more potent antioxidants for potential use as therapeutic agents as well as preservatives. We report the first computational study on the electronic effects of ortho-substituents in dendritic tri-phenolic antioxidants, comprising a common phenol moiety and two other phenol units with electron-donating or electron-withdrawing substituents. Among the three proposed antioxidant mechanisms, sequential proton loss electron transfer (SPLET) was found to be the preferred mechanism in methanol for the dendritic antioxidants based on calculations using Gaussian 16. We then computed the total enthalpy values by cumulatively running SPLET for all three rings to estimate electronic effects of substituents on overall antioxidant activity of each dendritic antioxidant and establish their structure–activity relationships. Our results show that the electron-donating o-OCH3 group has a beneficial effect while the electron-withdrawing o-NO2 group has a negative effect on the antioxidant activity of the dendritic antioxidant. The o-Br and o-Cl groups did not show any appreciable effects. These results indicate that electron-donating groups such as o-methoxy are useful for designing potent dendritic antioxidants while the nitro and halogens do not add value to the radical scavenging antioxidant activity. We also found that the half-maximal inhibitory concentration (IC50) values of 2,2-diphenyl-1-picrylhydrazyl (DPPH) better correlate with the second step (electron transfer enthalpy, ETE) than the first step (proton affinity, PA) of the SPLET mechanism, implying that ETE is the better measure for estimating overall radical scavenging antioxidant activities.

Radical Chain Breaking Bis( ortho ‐organoselenium) Substituted Phenolic Antioxidants

2021 ◽  
Vol 16 (8) ◽  
pp. 966-973
Author(s):  
Aditya Upadhyay ◽  
Bhagat Singh Bhakuni ◽  
Rahul Meena ◽  
Sangit Kumar
Keyword(s):  
Phenolic Antioxidants ◽  
Radical Chain ◽  
Chain Breaking

scholarly journals Natural Chain-Breaking Antioxidants and Their Synthetic Analogs as Modulators of Oxidative Stress

Antioxidants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 624
Author(s):  
Vessela D. Kancheva ◽  
Maria Antonietta Dettori ◽  
Davide Fabbri ◽  
Petko Alov ◽  
Silvia E. Angelova ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Free Radicals ◽  
Density Functional ◽  
Quantitative Structure Activity Relationship ◽  
Structure Activity Relationship ◽  
Oxidation Products ◽  
Activity Relationship ◽  
Phenolic Antioxidants ◽  
Structure Activity ◽  
Chain Breaking

Oxidative stress is associated with the increased production of reactive oxygen species or with a significant decrease in the effectiveness of antioxidant enzymes and nonenzymatic defense. The penetration of oxygen and free radicals in the hydrophobic interior of biological membranes initiates radical disintegration of the hydrocarbon “tails” of the lipids. This process is known as “lipid peroxidation”, and the accumulation of the oxidation products as peroxides and the aldehydes and acids derived from them are often used as a measure of oxidative stress levels. In total, 40 phenolic antioxidants were selected for a comparative study and analysis of their chain-breaking antioxidant activity, and thus as modulators of oxidative stress. This included natural and natural-like ortho-methoxy and ortho-hydroxy phenols, nine of them newly synthesized. Applied experimental and theoretical methods (bulk lipid autoxidation, chemiluminescence, in silico methods such as density functional theory (DFT) and quantitative structure–activity relationship ((Q)SAR) modeling) were used to clarify their structure–activity relationship. Kinetics of non-inhibited and inhibited lipid oxidation in close connection with inhibitor transformation under oxidative stress is considered. Special attention has been paid to chemical reactions resulting in the initiation of free radicals, a key stage of oxidative stress. Effects of substituents in the side chains and in the phenolic ring of hydroxylated phenols and biphenols, and the concentration were discussed.

Comparison of the Efficiencies of the Fused Heterocyclic Compounds, 9H-Xanthene-2,7-diols, and Related Chain-Breaking Phenolic Antioxidants

1996 ◽  
Vol 69 (6) ◽  
pp. 1713-1717 ◽  
Author(s):  
Tatsuo Yamamura ◽  
Takafumi Ishida ◽  
Hiroyuki Ueyama ◽  
Hirokazu Hayashida ◽  
Takuya Ishimaru ◽  
...  
Keyword(s):  
Heterocyclic Compounds ◽  
Phenolic Antioxidants ◽  
Chain Breaking
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