Carbohydrates/Radiolysis/O-glycoside bond/Cleavage. The formation of products resulting from the O-glycoside bond cleavage following radiolysis of aqueous solutions of methyl- α -D-glucopyranoside (I), 3-O-methyl- α -D-glucopyranose (II), maltose, lactose, gentiobiose and cellobiose were studied. Radiation-induced destruction yields were also determined for dextran, laminarin and trimethylcelulose upon irradiation of their aqueous solutions. Oxygen, quinones and compounds capable of forming quinoid structures were found to inhibit radiation-induced homolytic destruction processes taking place in glycosides, di- and polysaccharides. The data obtained in this study enabled the authors to demonstrate an important role played by the fragmentation reaction of C-2 radicals which were generated from the starting substances in the formation of final radiolysis products.

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Homolytic Cleavage of the O-glycoside Bond in Carbohydrates: A Steady-state Radiolysis Study

Route of glycerol conversion and product generation via TiO2-induced photocatalytic oxidation in the presence of H2O2

Reaction between lawsone and aminophenol derivatives: Synthesis, characterization, molecular structures and antiproliferative activity

Synthesis and biological evaluation of copper (II) complexes of sterically hindered o-aminophenol derivatives as antimicrobial agents.

Based on product yield data on radiolysis of hexane, ethanol and 3 M aqueous ethylene glycol solutions, the ability of a number of arylamine, aminophenol and quinonimine derivatives to affect processes involving peroxyl, alkyl or alpha-hydroxyalkyl radicals was assessed. It has been shown that the introduction of a hydroxyl group into aromatic amine structure enhances its antioxidant performance and makes it significantly more reactive with respect to carbon-centered organic radicals. Replacement of the hydrogen atom of a hydroxyl group by a methyl group decreases the anti-radical activity of aminophenols drastically. Compounds containing (or capable of forming) a quinonimine moiety interact with alkyl or alpha-hydroxyalkyl radicals most effectively, suppressing recombination and fragmentation reactions of the latter. In the sequence: aromatic amines--aminophenols--quinonimines, a trend towards enhancement of the ability of the compounds studied to react with carbon-centered radicals was noted. Also, this study presents for the first time evidence of riboflavin reactivity with respect to organic radicals.

Reactions of Arylamine and Aminophenol Derivatives, and Riboflavin with Organic Radicals

Investigation of effects produced by 26 various phenol and diphenol derivatives, including industrial and natural antioxidants (ionol, bis-phenol 2246, α-tocopherol), on final product yields of radiation-induced free-radical processes involving peroxyl, alkyl, α-hydroxyalkyl and α,β-dihydroxyalkyl radicals has been performed. Ionol and bis-phenol 2246 have been shown to be more effective than α-tocopherol or diphenol derivatives in suppressing hydrocarbon oxidation processes. At the same time, α-tocopherol and its water-soluble analogues, as well as diphenol-based substances, are more effective than phenol derivatives in regulating various homolytic processes involving carbon-centered radicals. This fact can be accounted for by taking into consideration the contribution to formation of the final product set and the respective yields made by semiquinone radicals and compounds with quinoid structure arising in the course of homolytic transformations in systems containing diphenol derivatives.

Effects of phenolic compounds on reactions involving various organic radicals.

Effects of quinones on free-radical processes of oxidation and fragmentation of hydroxyl-containing organic compounds

The radiation-chemical yields were determined for the products of γ-radiation induced oxidation of hexane and ethanol in the presence of natural and synthetic phenolic compounds and quinones. It was found that the commercial antioxidants ionol and bisphenol 2246 more effectively inhibit the hexane oxidation process while α-tocopherol and quinones are superior to other test compounds in the suppression of ethanol oxidation. The results indicate that the antioxidant properties of phenolic compounds and quinones depend not only on their structure but also on the nature of the oxidation substrate. The cause of this phenomenon is discussed.

Effect of phenolic compounds and quinones on radiation-induced oxidation processes of hexane and ethanol

In the course of radiation-induced free-radical transformations of hexane and ethanol, pyrocatechol and hydroquinone derivatives, as well as their respective quinones, are more effective than phenol and resorcinol derivatives in controlling reactions that involve alkyl and hydroxyalkyl radicals. The opposite result takes place in the inhibition by phenols of hexane oxidation in which the key role belongs to the peroxyl radicals generated from the starting compounds.

Reaction of Sterically Congested Phenols and Quinones with Organic Radicals

C6-Substituted derivatives of 3,5-di-tert-butyl-1,2-dihydroxybenzene have been synthesized, and their effect on radiation-induced free-radical oxidation of n-hexane and production of reactive oxygen and chlorine forms in neutrophils have been studied. It has been shown the introduction of the phenylhydrazone and phenylazomethine groups significantly increases the antioxidant activity of pyrocatechol derivatives. For six compounds, the ability to prevent the development of oxidative stress due to hyperproduction of active oxygen intermediates and HOCl/OCl− in neutrophils has been revealed.

Synthesis of 3,5-Di-tert-butyl-1,2-dihydroxybenzene Derivatives and Their Effect on Free-Radical Oxidation of Hexane and Oxygen Activation Ability of Neutrophils

N. I. Ostrovskaya

Papers

Effects of phenolic compounds on reactions involving various organic radicals.

Effects of quinones on free-radical processes of oxidation and fragmentation of hydroxyl-containing organic compounds

Effect of phenolic compounds and quinones on radiation-induced oxidation processes of hexane and ethanol

Reaction of Sterically Congested Phenols and Quinones with Organic Radicals

Synthesis of 3,5-Di-tert-butyl-1,2-dihydroxybenzene Derivatives and Their Effect on Free-Radical Oxidation of Hexane and Oxygen Activation Ability of Neutrophils