A change in the number of micelles was found to affect the kinetics of oxygen absorption of the entire microheterogeneous system, primarily the type of chain termination (310 K) as evidenced by the results of the study of the oxidation of methyl linoleate (LH) in cetyltrimethylammonium bromide (CTAB) micelles. Mixed micelles are formed, and the probability of isomerization and decomposition of peroxyl radicals of the substrate (LO2•) with the formation of HO2• increases. Given the hydrophilic character of HO2•, it can be assumed that these radicals diffuse to the aqueous phase to a higher extent, whereas the disproportionation in the organic phase is less pronounced. This leads to a decrease in the chain termination rate, which is kinetically described as a formally linear chain termination. As a result, the LH oxidation rate in CTAB micelles increases.

By combining kinetic and physicochemical methods with computer simulation, new information was obtained on the oxidation of methyllinoleate (LH) in micelles of sodium dodecyl sulfate (SDS) at 323 K. The dynamics of the process is related to the nature of the change in the volume of the micellar phase (Vmic). A gradual increase in Vmic leads to a decrease in the concentration of the oxidation substrate. This change occurs not only due to chemical reactions, but also due to a change in the volume of the microreactor in which the chemical transformation takes place. The accumulation of hydroperoxides inside those micelles in which LH is oxidized leads to the transformation of their structure and the formation of mixed micelles. Kinetic analysis shows that chain termination can occur by a mixed mechanism. The reaction order according to the initiator varies from 0.61 to 0.71. Leading oxidation chains, peroxy radicals (LO2•), are involved in both quadratic and linear termination. Linear termination occurs with the participation of hydroperoxyl radicals (HO2•). The formation of HO2• is due to the reaction LO2• → → product + HO2• occurring in the organic phase. The resulting HO2• goes into the aqueous phase, where the rate of their disproportionation is very low. Formally, this is fixed as a linear open circuit.

The initiated oxidation of 4,7-dihydro-1,3-dioxepine and 2-isopropyl-4,7-dihydro-1,3-dioxepine with molecular oxygen in the liquid phase (323 K) was studied. Microvolumetry, IR Fourier-transform spectroscopy, 1H NMR spectroscopy, potentiometry in combination with computer simulation and quantum chemical calculations were used. It was found that during the oxidation process, continuation of chains is realized due to the abstraction of a hydrogen atom by the peroxyl radical from the CH bond of the cycloolefin weakened by conjugation.

The effect of catecholamines on the oxidation of methyl linoleate in Triton X-100 micelles is studied. It is established that catecholamines do not inhibit oxidation at a physiological pH value of 7.4. Inhibition is only possible in the presence of the superoxide dismutase enzyme or at lower pH levels. The reason for this effect is the interaction of anionic forms of phenols and phenoxyl radicals with oxygen to form superoxide anion radicals. The high values of the inhibition coefficients for catecholamines in the presence of superoxide dismutase are due to the reactions of the resulting orthoquinones, leading to the regeneration of OH groups.

The purpose of the paper is to analyze effects induced by confining molecules in molecular cages, nano-bubbles, and enzymatic sites. In the focus of the paper is the confinement of reagents by enzymes, which allows controlling their functioning and efficiency by isotopic substitution. By using nuclear magnetic ions of magnesium, calcium, and zinc, catalyzing enzymatic ATP and DNA synthesis, the new radical pair mechanism is discovered. It is induced by compression of enzymatic sites and strongly increases ATP yield by ATP synthesizing enzymes. It decreases by 3−5 times the rate of the DNA synthesis and even more strongly, by 30−50 times, increases mortality of the cancer cells. This discovery elucidates new frontiers in gene chemistry and medicine.

The rate constants and kinetic coefficients of inhibition (fkin) for olefins oxidized with the transition metal compounds (Mn) were measured by highly sensitive microvolumometry at 323 K in combination with kinetic modeling. The cyclic mechanism of the reactions of hydroxyl radicals with Mn leading to the multiple chain termination was confirmed as indicated by the observed effect of long-term inhibition of the oxidation of the substrates with Mn and obtained values of fkin > 102.

A kinetic model of polyunsaturated fatty acids (PUFAs) radical chain oxidation in micelles is presented, taking into account the diffusion of active intermediates between aqueous and organic phases, and its effect on the detailed mechanism of the process. The model made it possible to indirectly involve the structural changes of micelles and their kinetic characteristics by varying the actual values of the reactions rate constants. The modeling results are in good agreement with experimental data for the oxidation of methyl linoleate and linoleic acid.

The binding of aminoxyls to polymers extends their potential use as antioxidants and EPR-reporting groups and opens up new horizons for tailoring new smart materials. In this work, we synthesized and characterized non-sulfated and N-sulfated water-soluble amphiphilic chitosans with a critical micelle concentration of 0.02-0.05 mg/mL that contain 13-18% of aminoglycosides bound with various aminoxyls. Chitosan-polyaminoxyls (CPAs) formed micelles with hydrodynamic radii Rh of ca. 100 nm. The EPR spectra of CPAs were found to depend on the rigidity of the aminoxyl-polymer bond and structural changes caused by sulfation. CPAs demonstrated antioxidant capacity/activity in three tests against reactive oxygen species (ROS) of various nature. The charge of micelles and structure of aminoxyls significantly affected their antioxidant properties. CPAs were low toxic against tumor (HepG2, HeLa, A-172) and non-cancerous (Vero) cells (IC50 > 0.8 mM of aminoglycosides). Sulfated CPAs showed better water solubility and the ability of binding and retaining the anti-tumor antibiotic daunorubicin (DAU). DAU-loaded micelles of CPAs (CPAs-DAU) demonstrated a 1.5-4-fold potentiation of DAU cytotoxicity against several cell lines. CPAs-DAU micelles were found to affect the cell cycle in a manner markedly different from that of free DAU. Our results demonstrated the ability of CPAs to act as bioactive drug delivery vehicles.

Using the model of methyl linoleate (LH) oxidation in micelles, the effect of cysteine on the antioxidant activity of nitroxyl radicals (NR) in micelles is studied. It is found that cysteine enhances the antioxidant effect of NR with a low reduction potential of the oxoammonium cation + nitroxyl radical pair, which is due to the formation of the corresponding hydroxylamines (HA).

Highly sensitive microvolumometry at 323 K is used in combination with kinetic modeling to measure the rate constants (k4) and kinetic coefficients of inhibition (fkin) of the reaction of 1,4-substituted butadiene oxidation by hydroperoxyl radicals ( $${\text{HO}}_{2}^{ \bullet }$$ ) in the presence of antioxidants (InH): 1,4-hydroquinone and 1,4-benzoquinone. The cyclic mechanism of interaction between $${\text{HO}}_{2}^{ \bullet }$$ and InH is confirmed: it leads to multiple chain termination, as is demonstrated by the observed long-term inhibition of the oxidation of substrates by hydroquinone and benzoquinone, and the obtained fkin > 102. It is shown that the drop in the value of k4 upon replacing –C6H5 substituent at the double bond in 1,4-substituted butadiene with –COOCH3 is due to the influence of specific solvation.

Initiated and inhibited oxidation of 2-methyl-2-vinyl-gem-dichlorocyclopropane has been studied. It has been found that in the oxidation process, chain propagation occurs via the addition of a polyperoxy radical to the double bond. The studied monomer is close to methacrylic acid esters in activity. The inhibiting effect of phenol and amine antioxidants and stable nitroxyl radicals on the radical chain oxidation of 2-methyl-2-vinyl-gem-dichlorocyclopropane has been examined, and amines and nitroxyls have been shown to repeatedly terminate chains due to the regeneration of the inhibitor.

The kinetics of oxygen absorption during the oxidation of methyl linoleate in Triton X-100 micelles has been studied. The order of the reaction with respect to the initiator diminishes from 1 to 0.6 with an increase in the total content of Triton X-100 per the unit volume of solution, since by the time of reaching the maximum oxygen absorption rate, the system consists of mixed micelles, which intercept the radicals generated by the initiator. The results of the analysis can be used to assess the dynamics of solubilization of hydrophobic substrates for creating a technique to test the antioxidant activity of biologically important compounds.

Kinetics of the reduction of nitroxides with cysteine in the presence of a source of superoxide radicals was studied. The reactivity of nitroxides in this process is determined by the reduction potential of the N-oxoammonium cation / nitroxide pair. The rate-limiting step of the reaction is the nitroxide oxidation by the hydroperoxyl radical to the N-oxoammonium cation.

The conformations of molecules in a diene (butadiene, isoprene) complex with hydrogen peroxide and isopropyl alcohol, for which local energy minima are identified, and a mechanism of hydrogen peroxide decomposition have been studied by the quantum-chemical density functional theory method. It has been shown that depending on the initial multiplicity of the system, the decomposition can result in the formation of different intermediate and final products, which indicates the probability of singlet to triplet conversion of hydrogen peroxide in the real system.

The cytotoxicity and antioxidant effects of chitosan-(poly)nitoxides of different molecular weights containing a nitroxide radical of the piperidine structure were studied on tumor (HeLa, A172, and HepG2) and normal (Vero) cell lines. The chitosan-(poly)nitroxides exhibited low cytotoxicity. Under conditions of oxidative stress induced with tert -butyl hydroperoxide, the most pronounced decrease in ROS levels in the presence of chitosan-(poly)nitroxides was observed in normal cells. In cell homogenates, the decrease in malondialdehyde levels was observed only in the presence of low-molecular-weight chitosan-(poly)nitroxide irrespective of the cell line. Our data demonstrate that the cell-specific antioxidant properties of chitosan-(poly)nitroxides are related to their penetration into cells and interaction with intracellular membranes.

ABSTRACT A combination of microcalorimetry, the rotating sector method, and ESR at 323 K in the environment of 10 solvents of different polarities was used to measure rate constants of addition of hydroperoxide radicals ( ) to π bonds of trans ‐1,2‐diphenylethylene and trans,trans ‐1,4‐diphenylbutadiene‐1,3 ( k 2 ) and disproportionation rate constants of these radicals ( k 3 ). With increasing dielectric constant of the medium, k 2 values increase from 69 to 410 M −1 · s −1 , and k 3 values almost do not change and are in the range of (1.0 ± 0.2) × 10 8 M −1 · s −1 . A linear dependence of logarithm values of rate constants from the dielectric constant of the medium in the coordinates of the Kirkwood–Onsager equation was found that allows to make a conclusion about the effect of nonspecific solvation in the studied systems. The quantum‐chemical analysis (NWChem, DFT B3LYP/6‐311G**) of the detailed mechanism for addition shows that the influence of the medium polarity reflects the superposition of the effects of nonspecific and specific solvation. The scale of the polar effect will depend on how different solvation energies of the transition and the initial reaction complexes. If a value of the solvation energy of the transition complex is larger than the solvation energy of the initial reaction complex, then the reaction rate should increase with an increase of the solvent's polarity and decrease otherwise.