Antirad compounds

Antirad compounds decrease the rate of reactions including both crosslinking and chain scission. As a result they often provide protection against polymer degradation. Antirads include aromatic amines, quinones, aromatic sulfur and nitrogen compounds. These materials are highly 

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Different model systems and different methods are used to evaluate the antioxidant properties of flavonoids. The stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH), which changes color after being reduced by an antiradical compound, was employed to study the antioxidant properties of isoflavones genistein (42) and daidzein (40), flavones apigenin (23) and lute-... 

Effect of Antirad Agents on the Scission Yield of a Natural Rubber Compound... 

Efforts to achieve a retardation of cross-linking in elastomers are based on the general assumption of a radical mechanism for retardation cross-linking and the possibility of its inhibition by a deactivation of the reactive macromolecular radical [33]. These compounds generally contain one or more labile hydrogen atoms, which after, donation of this atom, will form relatively inactive radicals. Typical antirad agents are quinones, hydroquinones, and aromatic amines (phenyl and napthylamines). 

In the context of the theoretically existing problems, a need exists to investigate the antiradical efficacy of compounds independent of pH value or polarity of the solvent, respectively. These problems are particularly relevant in the design of new pharmaceutical antioxidant preparations for specialized therapeutic applications. 

ACW—Integral Antiradical Capacity of Water-Soluble Compounds... 

The inhibition of lipid peroxidation by metalloporphyrins apparently depends on metal ions because only compounds with transition metals were efficient inhibitors. Therefore, the most probable mechanism of inhibitory effects of metalloporphyrins should be their disuniting activity. Manganese metalloporphyrins seem to be more effective inhibitors than Trolox (/5o = 204 pmol I 1) and rutin (/50 112 pmol I 1), and practically equal to SOD (/50= 15 pmol I 1). The mechanism of inhibitory activity of manganese and zinc metalloporphyrins might be compared with that of copper- and iron-flavonoid complexes [167,168], which exhibited enhanced antiradical properties due to additional superoxide-dismuting activity. 

Many of the studied radical-accepting compounds were found to reduce the yield of scissions. - The antirads tested proved effective not only in the presence of air but also in its absence (see Table 5.3). 

The system protecting organisms from free radical excess comprises enzymes with oxide reductive activity, non-enzyme proteins, polypeptides, water and oil-soluble vitamins, SH-containing amino acids, flavonoids, carotinoids, etc. [40], Most of these compounds prevent oxidative stress evolution by interrupting chain oxidative reactions. That is why these substances are called substances with antiradical activity as well as antioxidants (AO). Foodstuff, nutrients and some drugs are sources of most antioxidants. 

There is an increasing interest in the quantity and composition of phenols in maple sap and syrup, due to the antioxidant, antiradical, and antimutagenic activities of these compounds (Theriault et ah, 2006). 

Theriault, M., Caillet, S., Kermasha, S., and Lacroix, M. (2006). Antioxidant, antiradical and antimutagenic activities of phenolic compounds present in maple products. Food Chem. 98, 490-501. 

Compound TP-2 containing two OH groups has the highest antiradical activity, which agrees with the literature data that polyphenols of the pyrocat-echol series are characterized by the high values of the rate constant [ 16]. 

The presence of the oxygen atom in oposition with respect to the OH group of terpenephenols was found to decrease the antiradical activity of o-alkoxy compared o-alkyl substituted compounds by a factor of 6.5 for isobomylphenols and about 3.9 for isocamphylphenols owing to the intramolecular H-bond formation. 

Borneol is a major compound of Cinnamomum burmannii Nees leaves oil (Lauraceae), being present up to 78.6%. Other constituents are bornyl acetate, (-)-spathulenol, and eucalyptol. The oil was investigated for its antiradical properties in DPPH and ABTS assays and showed moderate... 

In both CL systems the key measured parameter for determining of the total water-soluble blood serum component AOA (ACW - integral antiradical capacity of water soluble compounds ) is the latent period. It decides as time from the oxidation initiation moment to a point of intersection on an axis of time of the tangent attached to CL-curve in the point corresponding to a maximum of its first derivative dl/dt (Figure 18.7). Calibration of devices was carried out on ascorbic acid, and the total AOA of water-soluble components (ACW) was expressed in the equivalent ascorbic acid content in one liter of blood serum (pmol/L). The measurement error of this parameter for the first device made no more than 20%, for the second didn t exceed 5%. 

FIGURE 18.4 Correlation of ACW measurement results for donors and recipients (ACW - integral antiradical capacity of water soluble compounds ) for model with hemoglobin (ACW, pmol/L (Hb)) and with ABAP (ACW, pmol/L (ABAP)) r-correlate coefficient. 

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