[A new approach to studying the autoxidation of adrenaline: possibility of the determination of superoxide dismutase activity and the antioxidant properties of various preparations by polarography]

Synthesis of Cerium Oxide Nanoparticles in a Bacterial Nanocellulose Matrix and the Study of Their Oxidizing and Reducing Properties

A soft synthesis of nanoceria with non-stoichiometric composition (33% Ce3+/67% Ce4+) named CeO2 NPs in bacterial cellulose (BC) matrix in the form of aerogel and hydrogel with controlled CeO2 NPs content was proposed. The advantage of CeO2 NPs synthesis in BC is the use of systemic antacid API–trisamine as a precursor, which did not destruct cellulose at room temperature and enabled a reduction in the duration of synthesis and the number of washes. Moreover, this method resulted in the subsequent uniform distribution of CeO2 NPs in the BC matrix due to cerium (III) nitrate sorption in the BC matrix. CeO2 NPs (0.1–50.0%) in the BC matrix had a fluorite structure with a size of 3–5 nm; the specific surface area of the composites was 233.728 m2/g. CeO2 NPs in the BC-CeO2 NPs composite demonstrated SOD-like activity in the processes of oxidation and reduction of cytochrome c (cyt c3+/cyt c2+), as well as epinephrine to inhibit its auto-oxidation in aqueous solutions by 33–63% relative to the control. In vitro experiments on rat blood showed a decrease in the MDA level and an increase in the activity of antioxidant defense enzymes–SOD by 24% and G6PDH by 2.0–2.5 times. Therefore, BC-CeO2 NPs can be proposed for wound healing as antioxidant material.

The Effect of Zinc Oxide Nanoparticles on Properties and Burn Wound Healing Activity of Thixotropic Xymedone Gels

Zinc oxide nanoparticles (ZnO NPs) modified by oxopyrymidine alcohol, also known as xymedone (Xym), were obtained and studied using FTIR, UV-vis, and fluorescent spectroscopy, and SEM, BET, powder XRD, and DLS analysis. A formulation of thixotropic hydrophilic gels containing Carbopol-based Xym and ZnO NPs was developed. A vertical Franz cell with a cellulose acetate membrane was used as a model to investigate the passive diffusion of the gel components by AAS. The gel components—Xym and ZnO NPs—were shown to penetrate through acetyl cellulose membrane within 5–7 h depending on an initial amount, and its values were in the range of 56–77%. The penetration of modified ZnO NPs by Xym was more effective in contrast to ZnO NPs without modification. The burn wound healing activity of ZnO NPs–Xym gel was demonstrated on a thermal burn wound model on rats. SOD and GR activity was increased by 30–35% during ZnO NPs–Xym gel treatment, the burn area on 10 postburn day decreased by 10% in contrast to a positive control, Methyluracyl®® ointment.

Antioxidant Activity of New Copolymer Conjugates of Methoxyoligo(Ethylene Glycol)Methacrylate and Betulin Methacrylate with Cerium Oxide Nanoparticles In Vitro

The synthesis of two new copolymer conjugates of methoxyoligo(ethylene glycol)methacrylate MPEGMA and betulin methacrylate BM was developed via RAFT polymerization. The molar content of BM units was equal to 9–10 and 13–16 mol%, respectively (HPLC, ¹H and ¹³C NMR); molar weights were equal to 75000–115000. CeO₂ NPs as a component of the hybrid material were synthesized for the preparation of the composition with copolymer conjugates of MPEGMA and BM. We showed a significant increase in G6PDH and GR activities by 21–51% and 9–132%, respectively, which was due to the increase in NADPH concentration under the action of copolymers in vitro. The actions of copolymers and CeO₂ NPs combination were stronger than those of the individual components: the SOD activity increased by more than 30%, the catalase activity increased dose-dependently from 13 to 45%, and the GR activity increased to 49%. The maximum increase in enzyme activity was observed for the G6PDH from 54% to 151%. The MDA level dose-dependently increased by 3–15% under the action of copolymers compared with the control, and dose-dependently decreased by 3–12% in samples containing CeO₂ NPs only. CeO₂ NP–copolymer compositions can be used for the design of new biomimetic medical products with controlled antioxidant properties.

The Effect of Low-Energy Laser-Driven Ultrashort Pulsed Electron Beam Irradiation on Erythropoiesis and Oxidative Stress in Rats

Anemia is a commonly observed consequence of whole-body exposure to a dose of X-ray or gamma irradiation of the order of the mean lethal dose in mammals, and it is an important factor for the determination of the survival of animals. The aim of this study was to unravel the effect of laser-driven ultrashort pulsed electron beam (UPEB) irradiation on the process of erythropoiesis and the redox state in the organism. Wistar rats were exposed to laser-driven UPEB irradiation, after which the level of oxidative stress and the activities of different antioxidant enzymes, as well as blood smears, bone marrow imprints and sections, erythroblastic islets, hemoglobin and hematocrit, hepatic iron, DNA, and erythropoietin levels, were assessed on the 1st, 3rd, 7th, 14th, and 28th days after irradiation. Despite the fact that laser-driven UPEB irradiation requires quite low doses and repetition rates to achieve the LD₅₀ in rats, our findings suggest that whole-body exposure with this new type of irradiation causes relatively mild anemia in rats, with subsequent fast recovery up to the 28th day. Moreover, this novel type of irradiation causes highly intense processes of oxidative stress, which, despite being relatively extinguished, did not reach the physiologically stable level even at the 28th day after irradiation due to the violations in the antioxidant system of the organism.

Zinc Oxide Nanoparticles Protected with Terpenoids as a Substance in Redox Imbalance Normalization in Burns

Preliminary protection of zinc oxide nanoparticles (ZnO NPs) with terpenoids such as betulin, its derivatives, and essential oils components has been proposed to produce gel-like oleophilic and hydrophilic formulations. We studied the properties of gel-like dispersions of ZnO NPs with immobilized terpenoids and their effects on the activity of LDH, GR, G6PDH, restoration of redox balance of co-enzyme pairs NAD+/NADH and NADP+/NADPH, as well as the activity of SOD, catalase, AlDH in erythrocytes in the treatment of burns in rats. Hysteresis loops on the rheograms of studied dispersions characterize their thixotropic properties. ZnO NPs with betulin diphosphate in the water-ethanol medium lead to a 20-fold increase in the hydrodynamic radius at pH 7.3 compared to the initial ZnO NPs, and facilitate the formation of Zn2+ ions and their penetration into the viable epidermis, unlike oleophilic dispersions. All dispersions reduce the healing time by one and a half times compared with the untreated control group, increase the activity of LDH, GR, G6PDH, SOD, catalase, AlDH, and contribute to the normalization of coenzyme balance. Normalization of the redox balance and wound state was more effective using hydrophilic dispersions due to Zn2 + penetration.

Wound Healing Composite Materials of Bacterial Cellulose and Zinc Oxide Nanoparticles with Immobilized Betulin Diphosphate

A design of new nanocomposites of bacterial cellulose (BC) and betulin diphosphate (BDP) pre-impregnated into the surface of zinc oxide nanoparticles (ZnO NPs) for the production of wound dressings is proposed. The sizes of crystalline BC and ZnO NPs (5-25%) corresponded to 5-6 nm and 10-18 nm, respectively (powder X-ray diffractometry (PXRD), Fourier-infrared (FTIR), ultraviolet (UV), atomic absorption (AAS) and photoluminescence (PL) spectroscopies). The biological activity of the wound dressings "BC-ZnO NPs-BDP" was investigated in rats using a burn wound model. Morpho-histological studies have shown that more intensive healing was observed during treatment with hydrophilic nanocomposites than the oleophilic standard (ZnO NPs-BDP oleogel; p < 0.001). Treatment by both hydrophilic and lipophilic agents led to increases in antioxidant enzyme activity (superoxide dismutase (SOD), catalase) in erythrocytes and decreases in the malondialdehyde (MDA) concentration by 7, 10 and 21 days (p < 0.001). The microcirculation index was restored on the 3rd day after burn under treatment with BC-ZnO NPs-BDP wound dressings. The results of effective wound healing with BC-ZnO NPs-BDP nanocomposites can be explained by the synergistic effect of all nanocomposite components, which regulate oxygenation and microcirculation, reducing hypoxia and oxidative stress in a burn wound.

The New Pharmaceutical Compositions of Zinc Oxide Nanoparticles and Triterpenoids for the Burn Treatment

We studied oleogels containing zinc oxide nanoparticles (ZnO NPs) and lupane triterpenoids in sunflower oil for the treatment of burns. The modification of ZnO was carried out by treatment with alcohol solutions of betulin, betulonic acid, betulin diacetate and betulin diphosphate. The properties of modified ZnO NPs were studied by powder XRD (average sizes of 10-20 nm), FTIR (νZnO 450 cm-1), UV-vis (345-360 nm), and blue-violet emission (380-420 nm). The identification and assay of modified ZnO NPs and triterpenoids were estimated. The treatment by oleogels of deep II-degree burns was studied on rats using histological studies, Doppler flowmetry and evaluation of enzymes activity and malonic dialdehyde (MDA) level. After the action of oleogels, burn wound area, and the necrosis decreased twice on the 10th day in comparison with the 1st day after burn. The microcirculation index in the near-wound zone by 20-30% improved compared with the group without treatment. Evaluation of the enzyme activity and the MDA level after treatment by oleogels during the course of 10 days showed them returning to normal. The improvement of antioxidant biochemical indexes, as well as wounds' healing, was mainly determined by the influence of zinc oxide nanoparticles.

[Effect of the sulfur-containing compounds on the quinoid process of adrenaline autoxidation; potential neuroprotectors]

The superoxide-generating reaction of adrenaline autoxidation in an alkaline medium, used in vitro to identify the antioxidant properties of various compounds, simulates the complex multistep process of quinoid oxidation of catecholamines (CA) in the body. Sulfur-containing cysteine (Cys) and reduced glutathione (GSH), as well as oxidized glutathione (GSSG), have been shown to inhibit this process. The studied substances were considered as inhibitors of quinoid oxidation and are evaluated as antioxidants. The IC50 values for Cys and GSH were close to 7.5 mM. Inhibition by GSSG was weaker; represented approximately 50-70% of Cys and GSH. Other sulfur-containing compounds that differ in chemical structure, the amino acids taurine and methionine were ineffective. The interest in this model and the search for effective compounds acting on this reaction is associated with one of the mechanisms of the etiopathogenesis of Parkinson's disease (PD) discussed in the literature, which occurs when the biochemical transformations of dopamine CA and its quinoid oxidation process are violated. Cys, GSH and GSSG in the model system inhibit quinoid oxidation of adrenaline, as a result of which the formation of superoxide (O2 ·-) is also inhibited. Experiments with the superoxide-generating enzymatic reaction xanthine xanthioxidase, the chemistry of which is different and not related to formation of quinoid metabolites, showed that the studied substances did not inhibit O2 ·- formation in this model. Thus, it was established that the biologically active sulfur-containing compounds Cys, GSH and GSSG are specific inhibitors of quinoid oxidation of CA, and are likely to be able to play the role of a neuroprotector. It is proposed to use these compounds in the treatment and prevention of PD by activating their biosynthesis in the body.

Betulin-3,28-diphosphate as a Component of Combination Cytostatic Drugs for the Treatment of Ehrlich Ascites Carcinoma In Vitro and In Vivo Experiments

The activity of betulin-3,28-diphosphate (BDP) in combination with the cytostatics such as 5-fluorouracil (5-FU) and hydrazine sulfate (HS) was demonstrated by using the transplanted Ehrlich ascites carcinoma (EAC) in mice. The dose-dependent effect of combination drugs BDP + HS and BDP + 5-FU was revealed by in vitro experiments on rats. The synergetic effect of HS and BDP on oxidative stress and energy metabolism was established. The malonic dialdehyde (MDA) level both in plasma and erythrocytes decreased by 87 ± 2%, and the superoxide dismutase (SOD) activity increased by 105 ± 7% in comparison with the control. The combination of BDP + HS promoted the increase of lactate dehydrogenase (LDH) activity in the reverse reaction by 195 ± 21% compared to the control. The combination drug of 5-FU with BDP caused the synergetic decrease of the lipid peroxidation (LPO) intensity estimated by the MDA level decrease up to 14 ± 4% compared to pure compounds. Betulin-3,28-diphosphate in combination with cytostatics for EAC treatment improved the animal health status, as well as decreased the cytostatics dose that can be used in palliative therapy.

[Involvement of carbonate/bicarbonate ions in the superoxide-generating reaction of adrenaline autoxidation]

An important role of carbonate/bicarbonate ions has been recognized in the superoxide generating reaction of adrenaline autooxidation in an alkaline buffer (a model of quinoid adrenaline oxidation in the body). It is suggested that these ions are directly involved not only in formation of superoxide anion radical (О(2)(-)) but also other radicals derived from the carbonate/bicarbonate buffer. Using various buffers it was shown that the rate of accumulation of adrenochrome, the end product of adrenaline oxidation, and the rate of О(2)(-)· formation depend on concentration of carbonate/bicarbonate ions in the buffer and that these ions significantly accelerate adrenaline autooxidation thus demonstrating prooxidant properties. The detectable amount of diformazan, the product of nitro blue tetrazolium (NBT) reduction, was significantly higher than the amount of adrenochrome formed; taking into consideration the literature data on О(2)(-)· detection by NBT it is suggested that adrenaline autooxidation is accompanied by one-electron reduction not only of oxygen dissolved in the buffer and responsible for superoxide formation but possible carbon dioxide also dissolved in the buffer as well as carbonate/bicarbonate buffer components leading to formation of corresponding radicals. The plots of the dependence of the inhibition of adrenochrome and diformazan formation on the superoxide dismutase concentration have shown that not only superoxide radicals are formed during adrenaline autooxidation. Since carbonate/bicarbonate ions are known to be universally present in the living nature, their involvement in free radical processes proceeding in the organism is discussed.

Use of nitro blue tetrazolium in the reaction of adrenaline autooxidation for the determination of superoxide dismutase activity

Addition of nitro blue tetrazolium (NBT) into the reaction of adrenaline autooxidation allows to identify directly superoxide anion formation (О · ) in this superoxide-generating system. The kinetics of formation of adrenochrome and О · were compared under the same conditions. Three possible approaches to the use the adrenaline autooxidation reaction for determining the activity of superoxide dismutase (SOD) and revealing the antioxidant properties of various compounds are discussed. Two of these approaches have been described previously: the spectrophotometric method of the registration of adrenochrome, the final product of adrenaline autoxidation, at 347 nm (Sirota, 1999) and the polarographic method, based on determination of oxygen consumption for О · formation (Sirota, 2011). Here, a novel approach to this problem is presented; it consists in the spectrophotometric determination of О · using NBT. The application of this approach enables one to lower the pH of carbonate buffer from 10.5 to 9.7 and to decrease (4-fold) the amount of added adrenaline, i.e., to generate milder and more effective conditions for revealing and studying the antioxidant properties of examined materials.