Sterically hindered phenol–dextran conjugates: radical scavenging activity in water and water–organic media

Arefiev, D.V.; Домнина, Н. С.; Komarova, E. A.; Bilibin, A. Yu.

doi:10.1016/s0014-3057(99)00134-2

Cited by 17 publications

(11 citation statements)

References 7 publications

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“…Kinetic study on the reaction of DPPH-SO 3 Na with a salt of A in dioxane-water mixtures with known ionizing powers revealed linear dependence on Y [2,4], which is consistent with radical ion mechanism. Furthermore, the calculated ionizing power of the solvate shell of dextran for samples of I-A (Y = 6.7 ± 0.4) exceeded the reference value Y = 3.4393 for pure water [2], which may be rationalized assuming destructuring of water in the solvate shell of dextran. Just that process is responsible for reduction of the energy necessary for rupture of hydrogen bonds upon solvation of radical cation.…”

Section: Structural Factors Responsible For the Activitysupporting

confidence: 68%

“…As a result, macromolecular antioxidants (conjugates) were obtained, which were characterized by different structural parameters: molecular weight (M) of the base polymer, concentration of phenol fragments in the polymeric chain (γ, mol %), and nature of the polymer-antioxidant linker [1][2][3][4]. Such polymers as dextran (I), hydroxyethyl starch (II), polyethylene glycol (III), and polyvinyl alcohol (IV) and functionalized derivatives of sterically hindered phenols, capable of forming covalent bonds with hydroxy groups in a polymer, β-(4-hydroxy-3,5-di-tert-butyl)-phenylpropionic acid A, 4-hydroxy-3,5-di-tert-butylcinnamic acid B, α-methyl-(4-hydroxy-3,5-di-tertbutyl)phenylacetic acid C, and derivatives of 4-hydroxy-3,5-di-tert-butylbenzyl alcohol D and 2-hydroxy-3,5-di-tert-butylbenzyl alcohol E, were used as co-reagents (Table 1).…”

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confidence: 99%

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Structural factors responsible for the activity of macromolecular phenolic antioxidants

et al. 2011

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Hybrid macromolecular antioxidants based on hydrophilic polymers with chemically grafted sterically hindered phenol fragments in aqueous solution exhibited considerably higher antiradical activity than that typical of compositions consisting of a polymer and low-molecular phenol analogs. The activity of the examined antioxidants is determined mainly by formation of supramolecular structures in solution, as well as by the position of the phenolic fragment inside or outside hydrate shell. An important structural factor is the size of the spacer connecting the redox-active phenol ring with the polymer. R = H, SO 3 Na.Synthesis of hybrid compounds containing functionally different fragments in a single structure is one of the most promising lines in the design of antioxidants of new generation for biology and medicine. Advantages of hybrid structures may be enhanced antioxidant efficiency, the possibility for its targeted delivery in a biosystem to be protected, controllable solubility, and reduced toxicity.Up to now, methods have been developed for chemical modification of hydrophilic bio-and synthetic polymers with derivatives of sterically hindered phenols. As a result, macromolecular antioxidants (conjugates) were obtained, which were characterized by different structural parameters: molecular weight (M) of the base polymer, concentration of phenol fragments in the polymeric chain (γ, mol %), and nature of the polymer-antioxidant linker [1][2][3][4]. Such polymers as dextran (I), hydroxyethyl starch (II), polyethylene glycol (III), and polyvinyl alcohol (IV) and functionalized derivatives of sterically hindered phenols, capable of forming covalent bonds with hydroxy groups in a polymer, β-(4-hydroxy-3,5-di-tert-butyl)-phenylpropionic acid A, 4-hydroxy-3,5-di-tert-butylcinnamic acid B, α-methyl-(4-hydroxy-3,5-di-tertbutyl)phenylacetic acid C, and derivatives of 4-hydroxy-3,5-di-tert-butylbenzyl alcohol D and 2-hydroxy-3,5-di-tert-butylbenzyl alcohol E, were used as co-reagents (Table 1). The amount of sterically hindered phenol fragments attached to a polymer was determined by UV spectrophotometry (by measuring the absorption intensity of the aromatic chromophore).The activity of macromolecular antioxidants in comparison with low-molecular analogs was estimated by measuring the rate constants for their reactions with

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Section: Structural Factors Responsible For the Activitysupporting

confidence: 68%

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confidence: 99%

Structural factors responsible for the activity of macromolecular phenolic antioxidants

et al. 2011

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“…Typical procedures for the synthesis, isolation, and purification of HMAO are described in Ref. 12. The number of SHP frag ments grafted to the polymer was determined by spectropho tometry from the absorption of the aromatic chromophore (λ max = 275 nm, EtOH -water (1 : 1)) and expressed in terms of γ (mol.%) defined as the fraction of substituted units in the total number of the monomer units in the polymer.…”

Section: Methodsmentioning

confidence: 99%

Hybrid macromolecular antioxidants based on hydrophilic polymers and sterically hindered phenols

et al. 2007

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A novel class of biologically active substances was created. These are hybrid macromolecu lar antioxidants (HMAO) based on hydrophilic polymers with chemically grafted sterically hindered phenols with different structural parameters. The antiradical activities of HMAO were assessed in reactions with 2,2 diphenyl 1 picrylhydrazyl and the corresponding sodium sulfonate in various solvents. The mechanism that explains the substantially enhanced activi ties of HMAO in water was proposed. The state of HMAO in solutions was studied by viscosim etry and photon correlation spectroscopy. HMAO were assayed in biological models.

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“…It should be noted that the difference in the reaction rate constants K for SHP1 and SHP2 becomes much larger after their addition to PEGs. The reason for the greater efficiency of the conjugates is associated with the presence of a hydration shell around the hydrophilic polymer chain in which this reaction proceeds [16]. The hydrate shell of any hydrophilic polymer, including PEGs, has an increased ionizing ability as compared to bulk water, which determines the high radical reaction rate in the solutions of both conjugates.…”

Section: Resultsmentioning

confidence: 99%

Molecular characteristics and antioxidant activity of polyethylene glycols modified by sterically hindered phenols

et al. 2011

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Chemical modification of polyethylene glycols by antioxidants belonging to the class of sterically hindered phenols is used to obtain water-soluble conjugates differing in the structure of the joined antioxidant and molecular weight. The inclusion of hydrophobic end groups in polyethylene glycol molecules leads to a decrease in the lower critical mixing point of the solution as compared to the original polymer. Dilute solution viscometry and light scattering are used to determine the molecular-mass characteristics of the polymers and the hydrodynamic radii of single conjugate molecules. The mass fraction of single molecules in aqueous solutions of the conjugates is greater than 95%. The aggregates are micellar-type particles whose core is formed by the hydrophobic moieties of sterically hindered phenols. It is shown that the antiradical activity of the antioxidants 3-(3-tert-butyl-4-hydroxy-5-methylphenyl)-propionic acid and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid, which are used for the modification, differs only slightly, whereas the activity of the relevant conjugates increases significantly.

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Sterically hindered phenol–dextran conjugates: radical scavenging activity in water and water–organic media

Cited by 17 publications

References 7 publications

Structural factors responsible for the activity of macromolecular phenolic antioxidants

Structural factors responsible for the activity of macromolecular phenolic antioxidants

Hybrid macromolecular antioxidants based on hydrophilic polymers and sterically hindered phenols

Molecular characteristics and antioxidant activity of polyethylene glycols modified by sterically hindered phenols

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