Oxidation antioxidants

Cobalt(II) hydroxide [1307-86-4], Co(OH)2, is a pink, rhombic crystalline material containing about 61% cobalt. It is insoluble in water, but dissolves in acids and ammonium salt solutions. The material is prepared by mixing a cobalt salt solution and a sodium hydroxide solution. Because of the tendency of the cobalt(II) to oxidize, antioxidants (qv) are generally added. Dehydration occurs above 150°C. The hydroxide is a common starting material for the preparation of cobalt compounds. It is also used in paints and Hthographic printing inks and as a catalyst (see Paint). 

Figure 7.4. Schematic relationship showing effect of pro-oxidants, antioxidants and oxidation retarders on the oxygen uptake of a polymer...

The mechanism of secondary stabilization by antioxidants is demonstrated in Figure 15.5. TnT-nonylphenyl phosphites, derived from PCI3 and various alcohols, and thio-compounds are active as a secondary stabilizer [21], They are used to decompose peroxides into non-free-radical products, presumably by a polar mechanism. The secondary antioxidant is reacting with the hydroperoxide resulting in an oxidized antioxidant and an alcohol. The thio-compounds can react with two hydroperoxide molecules. 

Polyphosphazene Coated silica Magnesium oxide Antioxidants Peroxide... 

Fig. 2.2 Simplified scheme of oxidant/antioxidant regulation ofNF-KB activation. Different stimuli, leading to an increase of ROS generation inside the ceU, activate the phosphorylation of IkB inhibitory protein and the subsequent proteolysis. Thioredoxin (Trx) may reduce activated NF-kB proteins facilitating nuclear translocation.Qnce released from IkB, the NF-kB complex translocates into the nucleus and the binding to DNA domain in the promoters and enhancers of genes such as TNF-a, IL-1, proliferation and chemotactic factors, adhesion molecule. Some of these genes, in turn, may further induce NF-kB activation, leading to a vicious circle if the regulatory cellular system escapes from...

Evans P and Halliwell B. 2001. Micronutrients oxidant/antioxidant status. Br J Nutr 85 s67—s74. 

Arivazhagan S, Velmurugan B, Bhuvaneswari V and Nagini S. 2004. Effects of aqueous extracts of garlic (Allium sativum) and neem (Azadirachta indica) leaf on hepatic and blood oxidant-antioxidant status during experimental gastric carcinogenesis. J Med Food 7(3) 334—339. 

Because of the prevalence of degradation by oxidation, antioxidants are generally added. These antioxidants are generally compounds that readily react with free radicals or those that may act to lessen the effects of enticers such as UV radiation. 

Phenol-induced oxidative stress mediated by thiol oxidation, antioxidant depletion, and enhanced free radical production plays a key role in the deleterious activities of certain phenols. In this mode of DNA damage, the phenol does not interact with DNA directly and the observed genotoxicity is caused by an indirect mechanism of action induced by ROS. A direct mode of phenol-induced genotoxicity involves covalent DNA adduction derived from electrophilic species of phenols produced by metabolic activation. Oxidative metabolism of phenols can generate quinone intermediates that react covalently with N-1,N of dG to form benzetheno-type adducts. Our laboratory has also recently shown that phenoxyl radicals can participate in direct radical addition reactions with C-8 of dG to form oxygen (O)-adducts. Because the metabolism of phenols can also generate C-adducts at C-8 of dG, a case can be made that phenoxyl radicals display ambident (O vs. C) electrophilicity in DNA adduction. 

Inflamed tissue associated with an oxidative stress as a consequence of a disbalance in the pro-oxidant/antioxidant homeostasis in chronic wounds is thought to drive a deleterious sequence of events that finally results in the non-healing state [29]. Experimental studies showed that wounds of delayed healing type are accompanied... 

Ames, Shigenaga, and Hagen, Oxidants, Antioxidants, and the Degenerative Diseases of Aging. ... 

Folate is a relatively unstable nutrient processing and storage conditions that promote oxidation are of particular concern since some of the forms of folate found in foods are easily oxidized. The reduced forms of folate (dihydro- and tetrahydrofolate) are oxidized to p-aminobenzoylglutamic acid and pterin-6-carboxylic acid, with a concomitant loss in vitamin activity. 5-Methyl-H4 folate can also be oxidized. Antioxidants (particularly ascorbic acid in the context of milk) can protect folate against destruction. The rate of the oxidative degradation of folate in foods depends on the derivative present and the food itself, particularly its pH, buffering capacity and concentration of catalytic trace elements and antioxidants. 

According to the theory of free radical oxidation, antioxidizing activities of chlorogenic acids are stipulated by their participation in reaction with free radicals. Chlorogenic and caffeic acids have high stoichiometric numbers and reactivity with peroxyl radicals as compared with trolox, the water-soluble analogue of tocopherol [48]. Considering... 

Alfassi. Z.B, S-CenteredRadicals. John Wiley Sons. Inc., New York. NY. 1999. Baskin. S.I. Oxidants, Antioxidants, and Free Radicals. Taylor Fianus. Dallas,... 

Taking into account the important role of balance in oxidant-antioxidant phenomena for human health and interrelation between internal and external factors, evaluation of oxidant-antioxidant state of human body fluids and natural resources of antioxidants is essential for therapy and prevention of diseases and adverse effects of environment. Thus, analysis of ready-made food and production processes monitoring are of great importance. 

Wang S. J. and Chen H. H. (2007). Presynaptic mechanisms underlying the a-lipoic acid facilitation of glutamate exocytosis in rat cerebral cortex nerve terminals. Neurochem. Int. 50 51-60. Warner D. S., Sheng H. X., and Batinic-Haberle I. (2004). Oxidants, antioxidants and the ischemic brain. J. Exp. Biol. 207 3221-3231. 

B7. Benzie, I. F., Chung, W., and Tomlinson, B., Simultaneous measurement of allantoin and urate in plasma Analytical evaluation and potential clinical application in oxidant antioxidant balance studies. Clin. Chem. 45, 901—904 (1999). 

I., Magnesium status and parameters of the oxidant-antioxidant balance in patients with chronic fatigue Effects of supplementation with magnesium. J. Am. Coll. Nutr. 19, 374-382 (2000). 

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