Reaction of polymethine dyes with hydroperoxides and free radicals

Zinatullina, K. M.; Касаикина, О. Т.; Кузьмин, В. А.; Khrameeva, N. P.; Shapiro, B. I.

doi:10.1007/s11172-016-1663-x

Cited by 12 publications

(3 citation statements)

References 10 publications

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“…In these conditions, the consumption rate of the acceptor will tend to expression (14), and the limiting value at an acceptor concentration tending to zero can be determined graphically. The value of k inh (15) can be estimated using the value of the recombination constant [ 28 ] equal to 2 k 2 = 5 × 10 4 (M·s −1 ). ln [InH] = ln [InH] 0 — a ·t a = k inh ·[RO 2 • ] at [InH] → 0 a → k inh ·(W i /2 k 2 ) 0.5 k inh = [dln(InH)/dt] C(InH)→0 /(W i /2 k 2 ) 0.5 …”

Section: Resultsmentioning

confidence: 99%

“…Therefore, the method, based on determining the initial slope of the semilogarithmic anamorphoses of the kinetic curves of the change in concentration on time in conditions of low acceptor concentrations, was used [28]. In this case, the consumption rate of the inhibitor will be described by the expression for the rate of the first-order reaction (12), where the coefficient a will be equal to expression (13).…”

Section: Determination Of the Reaction Rate Constant Of An Antioxidan...mentioning

confidence: 99%

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Kinetic Potentiometry as a Method for Studying the Interactions of Antioxidants with Peroxyl Radicals

Gerasimova,

Salimgareeva,

Magasumova

et al. 2023

Antioxidants

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This work presents a new method using kinetic potentiometry to study the thermodynamic and kinetic parameters of the reactions of antioxidants with peroxyl radicals. The rate constants of the reaction of antioxidants with radicals have been determined, and the groups of “fast” and “slow” antioxidants have been conventionally distinguished. Fast antioxidants include ascorbic, uric, gallic, chlorogenic, caffeic acids, glutathione, L-cysteine, and catechol with constant values from (1.05–9.25) × 103 M·s−1; “slow” antioxidants are α-tocopherol (in aqueous media), ionol, 2,6-ditretbutylphenol, and compounds of the azoloazine series, modified with polyphenolic fragments, with constant values from (4.00–8.50) × 102 M·s−1. It is shown that the value of the rate constant is directly related to the type of kinetic dependence of the potential recorded when an antioxidant is introduced into the solution of the radical initiator. It is shown that the method with the determination of the induction period is difficult in the study of “slow” antioxidants. It has been established that the area above the curve of the kinetic dependence Exp(∆E) is directly related to the amount of inhibited peroxyl radicals and can be used to assess the inhibitory properties of an antioxidant from a thermodynamic point of view. “Fixed time method” and “Initial rate method” were used. Positive correlations between the described method have been established. The utility of the parameter of the area above the curve of the kinetic dependence Exp(∆E) in the study of objects of complex composition is shown.

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Section: Resultsmentioning

confidence: 99%

Section: Determination Of the Reaction Rate Constant Of An Antioxidan...mentioning

confidence: 99%

Kinetic Potentiometry as a Method for Studying the Interactions of Antioxidants with Peroxyl Radicals

Gerasimova,

Salimgareeva,

Magasumova

et al. 2023

Antioxidants

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“…16 The rate of rad ical generation (W i ) in the ASH reaction with H 2 O 2 in deionized water were measured in a wide range of reagent concentrations by inhibitor method using a water-soluble acceptor (polymethine dye) with known spectral and kinetic properties. 15 Empirical functions of W i from thiol concentrations and H 2 O 2 for GSH (see lit. 10 ) and ASH can be represented as:…”

Section: Resultsmentioning

confidence: 99%

N-Acetylcysteine is an effective analog of glutathione in reactions with reactive oxygen species

et al. 2021

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The kinetic characteristics of the interaction of N-acetylcysteine (ASH) with reactive oxygen species (ROS), peroxyl radicals and hydrogen peroxide were determined. It was found that in terms of activity ASH in these reactions is similar to glutathione GSH, the main endogenous bioantioxidant. The kinetics of heat release in the interaction of GSH and ASH with H 2 O 2 was studied for the fi rst time by isothermal calorimetry. It is shown that the kinetic curves of heat release and changes in specifi c heat release rates practically coincide for both thiols taken in the stoichiometric ratio in the known reaction 2 TSH + H 2 O 2  TSST + 2 H 2 O.This indicates the relative autonomy of the S-H and S-S bonds in thiols and disulfi des, which are not aff ected by other groups in the molecule. At pH<7, ASH, like GSH, interacts with H 2 O 2 to form thiyl radicals, which initiate thiol-ene reactions with unsaturated phenol resveratrol. Under the same conditions, ASH ensures nearly the same radical initiation rates as GSH, and thiyl radicals from ASH are close in activity to GS • in chain propagation reactions.

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