Antioxidants action mechanism

Schwetlick, K. Habicher, W. D. Antioxidant action mechanisms of hindered amine stabilizers. Polym. Degrad. Stab. 2002, 78, 35-40. 

Denisov, E. T." ATheoretical Approach to the Optimization of Antioxidant Action." Mechanisms of Polymer Degradation and Stabilization, edited by G. Scott. London Elsevier Applied Science, 1990. 

Formation of hydroperoxides that become potential chain reaction initiators is characteristic of the phenolic antioxidant action mechanism. They decompose at high temperature (100-150 C) and a portion of the antioxidant is consumed by their deactivation. Their decomposition to form radicals is accelerated by light [46]. For this reason phenolic antioxidants are usually not effective at high temperatures and special antioxidants must then be used. These stabilizers combine effective parts of phenolic antioxidants to fragments that function by destroying peroxidic compounds. 

K. Schwetlick and W.D. Habicher, Organophosphorus antioxidants action mechanisms and new trends, Angewandte Makromolekulare Chemie, 232(l) 1522-9505, January 1995. 

The ability of carotenoids to act as antioxidants is closely related to their long-chain conjugated polyene structures (see Section 2.2 in Chapter 2). Two main types of antioxidant actions can be distinguished singlet oxygen quenching and reactions with radicals. The first mechanism occurs in vivo in plants and has been extensively studied in vitro. Reactions with radicals of different types have also been extensively studied in vitro under different conditions but their occurrence in vivo is still a matter of discussion. 

Scheme II.1 Mechanism of antioxidant action. After Grassie and Scott [1]. From N. Grassie and G. Scott, Polymer Degradation and Stabilisation, Cambridge University Press, Cambridge (1988). Reproduced by permission of Cambridge University Press...

CL accompanies many reactions of the liquid-phase oxidation of hydrocarbons, ketones, and other compounds. It was discovered in 1959 for liquid-phase ethylbenzene oxidation [219,220]. This phenomenon was intensively studied in the 1960s and 1970s, providing foundation for several methods of study of oxidation, decay of initiators, and kinetics of antioxidant action [12,17,221], Later this technique was effectively used to study the mechanism of solid polymer oxidation (see Chapter 13). 

The mechanism of antioxidant action on the oxidation of carbon-chain polymers is practically the same as that of hydrocarbon oxidation (see Chapters 14 and 15 and monographs [29 10]). The peculiarities lie in the specificity of diffusion and the cage effect in polymers. As described earlier, the reaction of peroxyl radicals with phenol occurs more slowly in the polymer matrix than in the liquid phase. This is due to the influence of the polymeric rigid cage on a bimolecular reaction (see earlier). The values of rate constants of macromolecular peroxyl radicals with phenols are collected in Table 19.7. 

Wiseman H, Quinn P, Halliwell B (1993) Tamoxifen and related compounds decrease membrane fluidity in liposomes mechanism for the antioxidant action of tamoxifen and relevance to its anticancer and cardioprotective actions FEBS Lett 330( 1) 53—56... 

Estrogen administration in postmenopausal women has been observed to produce cardioprotective benefits. The exact biomolecular mechanisms for this cardioprotection are unclear but it is likely that actions mediated both through the estrogen receptors, such as the beneficial alteration in lipid profiles and upregulation of the low-density lipoprotein (LDL) receptor, and independently of the estrogen receptors, such as antioxidant action, contribute to the observed cardioprotective effects of estrogens. 

Antioxidant action is one of the mechanisms that may contribute to the cardiovascular protective effects of soy and soy isoflavones. Antioxidant properties have been reported for isoflavones both in vitro and in vivo (see Section 7.3.5). 

Possible Mechanisms of the Chlorogenic acids Antioxidizing Action... 

The aim of the present work was to characterize the antioxidants formed in the reaction between histidine and glucose in order to elucidate the mechanism of their antioxidative action. The combination histidine-glucose was chosen since it previously was found to be one of the most effective combinations in model systems (13). 

These findings are of interest with respect to the mechanism of the antioxidative action of the MRP. The stable free radicals of the MRP might interact with the free radicals formed in the lipid oxidation and thus lead to an inhibition of the lipid oxidation chain mechanism. 

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