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 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

Antimalarial Drugs Exacerbate Rat Liver Microsomal Lipid Peroxidation in the Presence of Oxidants

2001 ◽  
Vol 21 (3) ◽  
pp. 353-359 ◽  
Author(s):  
E. Olatunde Farombi ◽  
Stanley Adoro ◽  
Samuel Uhunmwangho
Keyword(s):  
Lipid Peroxidation ◽  
Rat Liver ◽  
Lipid Hydroperoxide ◽  
Antimalarial Drugs ◽  
Oxygen Species ◽  
Radical Chain ◽  
Microsomal Lipid Peroxidation ◽  
Hydroperoxide Formation ◽  
Chain Breaking

The study was undertaken to evaluate the effect of prior treatment of rats with the antimalarial drugs amodiaquine (AQ) mefloquine (MQ) and halofantrine (HF) on rat liver microsomal lipid peroxidation in the presence of 1 mM FeSO4, 1 mM ascorbate and 0.2 mM H2O2 (oxidants). Ingestion of α-tocopheral, a radical chain-breaking antioxidant was also included to assess the role of antioxidants in the drug treatment. In the presence of oxidants AQ, MQ and HF elicited 288%, 175% and 225% increases in malondialdehyde (MDA) formation while the drugs induced 125%, 63% and 31% increases in the absence of oxidants respectively. Similarly, AQ, MQ and HF induced lipid hydroperoxide formation by 380%, 256%, 360% respectively in the presence of oxidants and 172%, 136% and 92% in the absence of exogenously added oxidants respectively. α-tocopherol reduced AQ, MQ and HF-induced MDA formation by 40%, 55% and 52% respectively and lipid hydroperoxide formation by 53%, 59% and 54% respectively. Similarly, α-tocopherol attenuated the AQ, MQ and HF-induced MDA formation by 49%, 51% and 51% in the presence of oxidants and lipid hydroperoxide formation by 61%, 62% and 47% respectively. The results indicate that rat liver microsomal lipid peroxidation could be enhanced by antimalarial drugs in the presence of reactive oxygen species and this effect could be ameliorated by treatment with antioxidants.

The antioxidant activities of phenolic antioxidants in free radical peroxidation of phospholipid membranes

1990 ◽  
Vol 68 (12) ◽  
pp. 2258-2269 ◽  
Author(s):  
Lawrence Ross Coates Barclay ◽  
Kimberly Ann Baskin ◽  
Kelly Andrea Dakin ◽  
Steven Jefffrey Locke ◽  
Melinda Ruth Vinqvist
Keyword(s):  
Hydrogen Bonding ◽  
Free Radical ◽  
Rate Constants ◽  
Antioxidant Activities ◽  
Hydrogen Abstraction ◽  
Peroxyl Radicals ◽  
Phenolic Antioxidants ◽  
Inhibition Rate ◽  
Radical Chain ◽  
Tert Butyl

Autoxidation of dilinoleoylphosphatidylcholine (DLPC) bilayers photoinitiated by benzophenone takes place by a free radical chain mechanism according to product studies of the cis, trans and trans, trans-9- and -13-linoleate hydroperoxides formed and kinetic studies of the reaction order as a function of light intensity. The absolute rate constant for hydrogen abstraction from DLPC bilayers by peroxyl radicals is found to be 36.1 M−1 s−1 at 37 °C. Preliminary measurements of activities of phenolic antioxidants, α-tocopherol (α-T), 2,2,5,7,8-pentamethyl-6-hydroxychroman (PMHC), 2,5,7,8-tetramethyl-6-hydroxychroman-2-carboxylate (Trolox), and 2,6-di-tert-butyl-4-methylphenol (BHT) by oxygen uptake studies during inhibition periods using photoinitiation gave uncorrected inhibition rate constants, Kinh, for α-T, PMHC, and Trolox several orders of magnitude lower than observed earlier in chlorobenzene. Three series of phenolic antioxidants, (a) polyalkyl-6-hydroxychromans, (b) polyalkyl-4-methoxyphenols, and (c) trialkylphenols, were examined for their antioxidant activities in DLPC membranes during thermally initiated autoxidation by azobis-2,4-dimethylvaleronitrile (DMVN). The corrected inhibition rate constants, kinh, observed in (a), α-T (5.8 × 103), PMHC (17.8 × 103), Trolox (5.8 × 103), 2,2-dimethyl-5,7-diisopropyl-6-hydroxychroman, 4a (55 × 103), and 2,2,5-trimethyl-7-tert-butyl-6-hydroxychroman, 5a (61 × 103) M−1 s−1, are dramatically lower, by several orders of magnitude, than those measured earlier in chlorobenzene and significantly lower (about 1/40–1/10) than those measured in solution in tert-butyl alcohol and less than kinh measurements (1/2–1/5) in aqueous SDS micelles. The kinh values for series (b) were 2,3,5,6-tetramethyl-4-methoxyphenol (TTMMP) (2.1 × 103), 2,3,6-trimethyl-4-methoxyphenol (TMMP) (10.4 × 103), and 2,6-di-tert-butyl-4-methoxyphenol (DBHA) (27.5 × 103) M−1 s−1 and for (c) were 2,6-di-tert-butyl-4-methylphenol (BHT) (3.7 × 103) and 2,4,6-trimethylphenol (TMP) (0.56 × 103) M−1 s−1. The results show an overall leveling and depression of antioxidant activities in DLPC membranes in the series (a), (b), (c) compared to those reported in solution in chlorobenzene, where large differences were attributed to steroelectronic effects of the para ether oxygen stabilizing the derived phenoxyl radicals in (a) and (b) types. The results in aqueous micellar and membrane systems are interpreted in terms of polar solvation effects. Hydrogen bonding by water at both the ether and phenolic groups decreases the activity of the (a) series. Hydrogen bonding at the phenolic hydroxyl appears to be the more significant factor since steric hindrance to H-bonding at hydroxyl allows 4a and 5a to be the most active antioxidants of the α-tocopherol series (a) and DBHA to be the most active antioxidant of the (b) series. Keywords: antioxidant activities, phenols, membranes, peroxidation, kinetics.

The Role of Certain Organic Sulfur Compounds as Preventive Antioxidants

1974 ◽  
Vol 47 (4) ◽  
pp. 949-959 ◽  
Author(s):  
J. Reid Shelton
Keyword(s):  
Oxidative Degradation ◽  
Polymeric Materials ◽  
Chain Scission ◽  
Peroxy Radicals ◽  
Radical Chain ◽  
Organic Sulfur Compounds ◽  
Chain Breaking ◽  
Degradation Of Properties ◽  
Free Radical Chain Reaction ◽  
Crosslinking Reactions

Abstract The mechanism of autoxidation of organic materials by elemental oxygen is a free radical chain reaction initiated by hydroperoxide decomposition to form alkoxy and peroxy radicals. Chain scission and crosslinking reactions occur, along with the formation of hydroperoxide, resulting in degradation of properties of polymeric materials. The presence of unsaturation in natural and synthetic rubbers makes them particularly vulnerable to autoxidation, and antioxidants are thus essential to provide protection against oxidative degradation. There are two ways in which antioxidants can function to retard autoxidation. Preventive antioxidants act in some way to reduce the rate of initiation, while chain-breaking antioxidants intercept the chain-propagating peroxy free radicals and thus terminate the chain mechanism. Both types include a variety of compounds and possible modes of action as indicated in the following classification:

Phenolic betalain as antioxidants: meta means more

2020 ◽  
Vol 92 (2) ◽  
pp. 243-253 ◽  
Author(s):  
Letícia C. P. Gonçalves ◽  
Nathana B. Lopes ◽  
Felipe A. Augusto ◽  
Renan M. Pioli ◽  
Caroline O. Machado ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Hydrogen Atom Transfer ◽  
Antioxidant Potential ◽  
Human Consumption ◽  
Ph Effects ◽  
Radical Chain ◽  
Proton Coupled Electron Transfer ◽  
Chain Breaking ◽  
The Relationship ◽  
Transfer Mechanisms

AbstractBetalains are phytochemicals of nutraceutical importance that emerged as potent antioxidants, preventing radical chain propagation and the deleterious health effects of oxidative stress. However, despite the wide application of betalains as color additives in products for human consumption, little is known about the relationship between their structure and antioxidant potential. Here we investigate the mechanism of antioxidant action of three regioisomeric phenolic betalains and show that the meta isomer has higher antiradical capacity than most natural betalains, anthocyanins and flavonoids. Structural and pH effects on redox and antiradical properties were investigated and the results are rationalized in light of quantum chemical calculations. Our results demonstrate that hydrogen atom transfer/proton-coupled electron transfer or sequential proton loss electron transfer mechanisms are plausible to explain the radical chain breaking properties of phenolic betalains in water. Furthermore, mesomeric effects are responsible for the stabilization of the resulting radical phenolic betalains. These findings are useful for the design of biocompatible antioxidants and for the development of novel additives for functional foods and cosmetics with high antioxidant potential.

The importance of peroxy radical chain-breaking reactions in the cool flame domain

1979 ◽  
Vol 34 ◽  
pp. 153-159 ◽  
Author(s):  
K.A. Sahetchian ◽  
A. Heiss ◽  
G.M.L. Dumas ◽  
R.I. Ben-Aim
Keyword(s):  
Peroxy Radical ◽  
Radical Chain ◽  
Cool Flame ◽  
Chain Breaking
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