Search Results (18)

Exercise-induced fatigue involves oxidative stress and metabolic dysregulation. While the anti-aging protein α-Klotho regulates metabolism and oxidative stress, its role in exercise fatigue is unexplored. This study investigated whether α-Klotho supplementation mitigates cumulative exercise-induced fatigue and elucidated the underlying tissue-specific mechanisms. Male C57BL/6J mice were divided into three groups (n = 10 per group), the control group, fatigue treated with saline, or α-Klotho (0.2 mg/kg, i.p. daily) group. Fatigue was induced by a 6-day exhaustive swimming protocol (5% body weight load). Tissues were collected 24h post-final exercise. Assessments included daily exhaustion time, grip strength, serum creatine kinase (CK), urea nitrogen (BUN), oxidative stress markers (H₂O₂, MDA, SOD, GSH/GSSG), tissue glycogen, and pathway protein expression (Western blot). α-Klotho supplementation prevented exercise-induced weight loss and restored grip strength. While exhaustive exercise markedly increased serum CK and BUN levels, α-Klotho selectively normalized CK without effecting serum BUN. α-Klotho attenuated oxidative damage by reducing hydrogen peroxide levels while enhancing antioxidant capacity, accompanied by activation of the NRF2/HO-1 pathway and further upregulation of PGC-1α. Notably, α-Klotho induced striking hepatic glycogen supercompensation through activation of the AKT/GS signaling pathway and upregulation of GLUT4, whereas muscle glycogen levels remained unchanged. In conclusion, α-Klotho ameliorates cumulative exercise-induced fatigue through dual recovery-phase mechanisms: NRF2/HO-1-mediated antioxidant protection in skeletal muscle and AKT/GS-triggered hepatic glycogen supercompensation, thereby facilitating oxidative stress resolution and enhancing energy reserve restoration. Full article

Alzheimer’s disease (AD) is a neurodegenerative condition in which amyloid-beta (Aβ) plaques trigger oxidative stress (OS) and neuroinflammation, causing memory loss. OS and neurodegeneration can also be caused by reactive astrocytes, thereby promoting AD via toxic metabolite accumulation in the astrocytic urea cycle. However, the effect of molecular hydrogen (H₂) on this cycle remains unknown. Therefore, we investigated whether H₂ treatment could reduce OS-induced neurodegeneration and memory loss. 5xFAD (n = 14) and wild-type (n = 15) mice were randomized into four groups and treated with either 3% hydrogen gas (H₂) or vehicle for 60 days. Cognitive behaviors were evaluated using the Morris water maze and Y-maze tests. In addition, we used biochemical assays to measure ammonia and hydrogen peroxide (H₂O₂) levels in the hippocampi of the mice and AβO-treated primary mouse astrocytes. Aβ, γ-aminobutyric acid (GABA), and the expression of inflammatory markers were evaluated using immunohistochemistry (IHC) and quantitative real-time polymerase chain reaction (qRT-PCR). We observed that H₂ treatment significantly prevented cognitive deficits, oxidative stress, the accumulation of toxic metabolites, and the increase in inflammatory markers in 5xFAD mice. These results suggest that H₂ therapy can mitigate toxic metabolites in the astrocytic urea cycle, thereby reducing neurodegeneration and memory loss in AD. Full article

To comparatively study the effects of cold plasma activation and chemical treatment on the adsorption capacities of biomass carbon nanofiber membranes (BCNMs), microcrystalline cellulose (MCC) and chitosan (CS) were used to fabricate porous BCNMs by electrospinning and carbonization. Two modification methods, including oxygen (O₂) plasma activation and chemical treatment using nitric acid (HNO₃), sulfuric acid (H₂SO₄), hydrogen peroxide (H₂O₂), and urea, were further employed to enhance their adsorption performance. Various carbonyl group (C=O), ether bond (C-O), carboxyl group (O-C=O) and pyridinic nitrogen (N), pyrrolic N, and quaternary N functional groups were successfully introduced onto the surface of the BCNMs by the two methods. The BCNM-O₂ showed optimal formaldehyde absorption capacity (120.67 mg g⁻¹), corresponding to its highest contents of N, O-containing functional groups, and intact network structure. However, chemical treatment in strong acid or oxidative solutions destructed the microporous structures and changed the size uniformity of fibers in the BCNMs, resulting in a decline in formaldehyde adsorption capacity. A synergistically physical–chemical adsorption took place during formaldehyde adsorption by the modified biomass nanofiber membranes, due to the coexistence of suitable functional groups and porous structures in the membranes. Full article

The oxidation of imines may give several products, such as oxaziridines, nitrones, amides, and other rearranged compounds. Therefore, its selectivity is a challenge that various methods have to face. The controversial selectivity of the oxidation of imines using urea hydrogen peroxide (UHP) catalyzed by methyltrioxorhenium (MTO) is addressed by varying the solvent, temperature, reaction time, amount of oxidant, and catalyst used. The reactivity and selectivity of the oxidation of imines proved to be particularly sensitive to the type of solvent. The use of methanol furnished the corresponding nitrones as the exclusive products, except for very hindered N-tert-alkyl substituted substrates. Using the ionic liquid [bmim]BF₄ as a solvent resulted in a complete switch in reactivity and selectivity. N-methyl substituted imines gave the corresponding amides, while imines with bulkier substituents at nitrogen did not show any reactivity. An exception was the C-phenyl,N-tert-butyl imine—the only substrate that was oxidized to the corresponding oxaziridine, albeit with low conversion. The results reported herein reaffirm the oxidation of imines with UHP/MTO in MeOH as the method of choice for their interconversion to nitrones. Full article

This study investigated the effects of exogenous nitric oxide (NO) on growth, antioxidant enzymes, and key nitrogen metabolism enzymes in pepper seedlings under high-temperature stress. In addition, targeted metabolomics was used to study the differential accumulation of amino acid metabolites, thereby providing theoretical support for the use of exogenous substances to mitigate high-temperature stress damage in plants. The results showed that high-temperature stress increased soluble sugar, soluble protein, amino acids, proline, malondialdehyde (MDA), and hydrogen peroxide (H₂O₂) content, electrolyte leakage, and superoxide anion (O₂^·-) production rate while altering the activities of antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX)] and key nitrogen metabolism enzymes [nitrate reductase (NR), glutamine synthetase (GS), glutamate dehydrogenase (GDH), and nitric oxide synthase (NOS)]. c-PTIO (2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide, an NO scavenger) exacerbates oxidative stress and further reduces NO content and enzyme activities. However, exogenous SNP (sodium nitroprusside, an NO donor) effectively alleviated these adverse effects by enhancing antioxidant defense mechanisms, increasing NO content, and normalizing amino acid metabolite levels (kynurenine, N-acetyl-L-tyrosine, L-methionine, urea, and creatine), thereby maintaining normal plant growth. These findings suggest that SNP can enhance stress tolerance in pepper seedlings by improving osmotic regulation, antioxidant capacity, and nitrogen metabolism, effectively mitigating the damage caused by high-temperature stress. Full article

Selective oxidation of ethylbenzene to acetophenne is an important process in both organic synthesis and fine chemicals diligence. The cobalt-based catalysts combined with nitrogen-doped carbon have received great attention in ethylbenzene (EB) oxidation. Here, a series of cobalt catalysts with metallic cobalt nanoparticles (NPs) encapsulated in nitrogen-doped graphite-like carbon shells (Co@NC) have been constructed through the one-pot pyrolysis method in the presence of different nitrogen-containing compounds (urea, dicyandiamide and melamine), and their catalytic performance in solvent-free oxidation of EB with tert-butyl hydrogen peroxide (TBHP) as an oxidant was investigated. Under optimized conditions, the UCo@NC (urea as nitrogen source) could afford 95.2% conversion of EB and 96.0% selectivity to acetophenone, and the substrate scalability was remarkable. Kinetics show that UCo@NC contributes to EB oxidation with an apparent activation energy of 32.3 kJ/mol. The synergistic effect between metallic cobalt NPs and nitrogen-doped graphite-like carbon layers was obviously observed and, especially, the graphitic N species plays a key role during the oxidation reaction. The structure–performance relationship illustrated that EB oxidation was a free radical reaction through 1-phenylethanol as an intermediate, and the possible reaction mechanistic has been proposed. Full article

Oxidase and peroxidase enzymes have attracted attention in various biotechnological industries due to their ease of synthesis, wide range of applications, and operation under mild conditions. Their applicability, however, is limited by their poor stability in harsher conditions and their non-reusability. As a result, several approaches such as enzyme engineering, medium engineering, and enzyme immobilization have been used to improve the enzyme properties. Several materials have been used as supports for these enzymes to increase their stability and reusability. This review focusses on the immobilization of oxidase and peroxidase enzymes on metal and metal oxide nanoparticle-polymer composite supports and the different methods used to achieve the immobilization. The application of the enzyme-metal/metal oxide-polymer biocatalysts in biosensing of hydrogen peroxide, glucose, pesticides, and herbicides as well as blood components such as cholesterol, urea, dopamine, and xanthine have been extensively reviewed. The application of the biocatalysts in wastewater treatment through degradation of dyes, pesticides, and other organic compounds has also been discussed. Full article

Bleached bamboo pulp, as a kind of natural cellulose, has received significant attention in the field of biomass materials due to its advantages of environmental protection and the abundance of raw materials. Low-temperature alkali/urea aqueous system is a green dissolution technology for cellulose, which has promising application prospects in the field of regenerated cellulose materials. However, bleached bamboo pulp, with high viscosity average molecular weight (Mη) and high crystallinity, is difficult to dissolve in an alkaline urea solvent system, restraining its practical application in the textile field. Herein, based on commercial bleached bamboo pulp with high Mη, a series of dissolvable bamboo pulps with suitable Mη was prepared using a method of adjusting the ratio of sodium hydroxide and hydrogen peroxide in the pulping process. Due to the hydroxyl radicals being able to react with hydroxyls of cellulose, molecular chains are cut down. Moreover, several regenerated cellulose hydrogels and films were fabricated in an ethanol coagulation bath or a citric acid coagulation bath, and the relationship between the properties of the regenerated materials and the Mη of the bamboo cellulose was systematically studied. The results showed that hydrogel/film had good mechanical properties, as the Mη is 8.3 × 10⁴ and the tensile strength of a regenerated film and the film have values up to 101 MPa and 3.19 MPa, respectively. In this contribution, a simple method of a one-step oxidation of hydroxyl radicals to prepare bamboo cellulose with diversified Mη is presented, providing an avenue for a preparation of dissolving pulp with different Mη in an alkali/urea dissolution system and expanding the practical applications of bamboo pulp in biomass-based materials, textiles, and biomedical materials. Full article

The introduction of alloplastic materials (meshes) in hernia surgery has improved patient outcome by a radical reduction of hernia recurrence rate, but discussion about the biocompatibility of these implanted materials continues since observations of surface alterations of polypropylene and other alloplastic materials were published. This study intends to investigate if additives supplemented to alloplastic mesh materials merge into the solution and become analyzable. Four polypropylene and one polyester alloplastic material were incubated in different media for three weeks: distilled water, saline solution, urea solution, formalin, and hydrogen peroxide. No swelling or other changes were observed. Infrared spectroscopy scanning of incubated alloplastic materials and NMR studies of extracted solutions were performed to investigate loss of plasticizers. The surface of the mesh materials did not show any alterations independent of the incubation medium. FT-IR spectra before and after incubation did not show any differences. NMR spectra showed leaching of different plasticizers (PEG, sterically hindered phenols, thioester), of which there was more for polypropylene less for polyester. This could be the reason for the loss of elasticity of the alloplastic materials with consecutive physically induced surface alterations. A mixture of chemical reactions (oxidative stress with additive leaching from polymer fiber) in connection with physical alterations (increased elasticity modulus by loss of plasticizers) seem to be a source of these PP and PE alterations. Full article

Patients with acute kidney injury (AKI) have an increased risk of cardiovascular disease. The underlying mechanism of AKI-induced heart injury is not well-understood. Hydrogen sulfide (H₂S), at physiological concentrations, has been implicated in cardiovascular protection through redox balance and vessel relaxation. Cystathionine gamma-lyase (CSE) plays an essential role in H₂S production in the heart. The present study investigated the effect of AKI on H₂S production and oxidative stress in the heart. AKI was induced by kidney ischemia-reperfusion in male and female Sprague-Dawley rats, which led to an increase in plasma creatinine and blood urea nitrogen levels. There was a significant increase in lipid peroxidation and a decrease in glutathione (antioxidant) levels in the plasma and heart, indicating systemic and cardiac oxidative stress. Kidney ischemia-reperfusion reduced CSE expression and H₂S production in the heart. There was a decrease in antioxidant transcription factor Nrf2 level in the nucleus and an increase in inflammatory cytokine (IL-6, TNF-α) expression in the heart. These results suggest that AKI can down-regulate CSE-mediated H₂S production, reduce glutathione levels and increase oxidative stress in the heart. This may contribute to an increased risk of cardiovascular disease in AKI. Full article

Hydrogen peroxide is a low-reactivity reactive oxygen species (ROS); however, it can easily penetrate cell membranes and produce highly reactive hydroxyl radical species through Fenton’s reaction. Its presence in abnormal amounts can lead to serious diseases in humans. Although the development of a simple, ultrasensitive, and selective method for H₂O₂ detection is crucial, this remains a strategic challenge. The peroxidase mimetic activity of palladium nanoclusters (PdNCs) has not previously been evaluated. In this study, we developed an ultrasensitive and selective colorimetric detection method for H₂O₂ using PdNCs. An unprecedented eco-friendly, cost-effective, and facile biological method was developed for the synthesis of PdNCs. This is the first report of the biosynthesis of PdNCs. The synthesized nanoclusters had a significantly narrow size distribution profile and high stability. The nanoclusters were demonstrated to possess a peroxidase mimetic activity that could oxidize peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB). Various interfering substances in serum (100 μM phenylalanine, cysteine, tryptophan, arginine, glucose, urea, Na⁺, Fe²⁺, PO₄³⁻, Mn⁺², Ca²⁺, Mg²⁺, Zn²⁺, NH₄⁺, and K⁺) were included to evaluate the selectivity of the assay, and oxidation of TMB occurred only in the presence of H₂O₂. Therefore, PdNCs show an efficient nanozyme for the peroxidase mimetic activity. The assay produced a sufficient signal at the ultralow concentration of 0.0625 µM H₂O₂. This colorimetric assay provides a real-time, rapid, and easy-to-use platform for the detection of H₂O₂ for clinical purposes. Full article

The metal-free CDots/g-C₃N₄ composite, normally used as the photocatalyst in H₂ generation and organic degradation, can also be applied as an environmental catalyst by in-situ production of strong oxidant hydroxyl radical (HO·) via catalytic decomposition of hydrogen peroxide (H₂O₂) without light irradiation. In this work, CDots/g-C₃N₄ composite was synthesized via an electrochemical method preparing CDots followed by the thermal polymerization of urea. Transmission electron microscopy (TEM), X-Ray diffraction (XRD), Fourier Transform Infrared (FTIR), N₂ adsorption/desorption isotherm and pore width distribution were carried out for characterization. The intrinsic catalytic performance, including kinetics and thermodynamic, was studied in terms of catalytic decomposition of H₂O₂ without light irradiation. The second-order rate constant of the reaction was calculated to be (1.42 ± 0.07) × 10⁻⁹ m·s⁻¹ and the activation energy was calculated to be (29.05 ± 0.80) kJ·mol⁻¹. Tris(hydroxymethyl) aminomethane (Tris) was selected to probe the produced HO· during the decomposing of H₂O₂ as well as to buffer the pH of the solution. The composite was shown to be base-catalyzed and the optimal performance was achieved at pH 8.0. A detailed mechanism involving the adsorb-catalyze double reaction site was proposed. Overall, CDots/g-C₃N₄ composite can be further applied in advanced oxidation technology in the presence of H₂O₂ and the instinct dynamics and the mechanism can be referred to further applications in related fields. Full article

Oxidative stress is an important etiology of chronic diseases and many studies have shown that natural products might alleviate oxidative stress-induced pathogenesis. The study aims to evaluate the effect of Argan oil and Syzygium aromaticum essential oil on hydrogen peroxide (H₂O₂)-induced liver, brain and kidney tissue toxicity as well as biochemical changes in wistar rats. The antioxidant content of Argan oil and Syzygium aromaticum essential oil was studied with the use of gas chromatography. The animals received daily by gavage, for 21 days, either distilled water, Syzygium aromaticum essential oil, Argan oil, H₂O₂ alone, H₂O₂ and Syzygium aromaticum essential oil, or H₂O₂ and Argan oil. Blood samples were withdrawn on day 21 for the biochemical blood tests, and the kidney, liver and brain tissue samples were prepared for histopathology examination. The results showed that the content of antioxidant compounds in Syzygium aromaticum essential oil is higher than that found in Argan oil. H₂O₂ increased level of blood urea, liver enzymes, total cholesterol, Low Density Lipoprotein (LDL-C), Triglycerides (TG) and Very Low Density Lipoprotein (VLDL), and decreased the total protein, albumin and High Density Lipoprotein-cholesterol (HDL-C). There was no significant effect on blood electrolyte or serum creatinine. The histopathology examination demonstrated that H₂O₂ induces dilatation in the central vein, inflammation and binucleation in the liver, congestion and hemorrhage in the brain, and congestion in the kidney. The H₂O₂-induced histopathological and biochemical changes have been significantly alleviated by Syzygium aromaticum essential oil or Argan oil. It is concluded that the Argan oil and especially the mixture of Argan oil with Syzygium aromaticum essential oil can reduce the oxidative damage caused by H₂O_2, and this will pave the way to investigate the protective effects of these natural substances in the diseases attributed to the high oxidative stress. Full article

Recently, graphene and graphene-related materials have attracted a great deal of attention due their unique physical, chemical, and biocompatibility properties and to their applications in biotechnology and medicine. However, the reports on the potential toxicity of graphene oxide (GO) in biological systems are very few. The present study investigated the response of kidneys in male Sprague-Dawley rats following exposure to 0, 10, 20 and 40 mg/Kg GO for five days. The results showed that administration of GOs significantly increased the activities of superoxide dismutase, catalase and glutathione peroxidase in a dose-dependent manner in the kidneys compared with control group. Serum creatinine and blood urea nitrogen levels were also significantly increased in rats intoxicated with GO compared with the control group. There was a significant elevation in the levels of hydrogen peroxide and lipid hydro peroxide in GOs-treated rats compared to control animals. Histopathological evaluation showed significant morphological alterations of kidneys in GO-treated rats compared to controls. Taken together, the results of this study demonstrate that GO is nephrotoxic and its toxicity may be mediated through oxidative stress. In the present work, however, we only provided preliminary information on toxicity of GO in rats; further experimental verification and mechanistic elucidation are required before GO widely used for biomedical applications. Full article

Hydrogen peroxide was encapsulated into a silica xerogel matrix by the sol-gel technique. The composite was tested as an oxidizing agent both under conventional and microwave conditions in a few model reactions: Noyori’s method of octanal and 2-octanol oxidation and cycloctene epoxidation in a 1,1,1-trifluoroethanol/Na₂WO₄ system. The results were compared with yields obtained for reactions with 30% H₂O₂ and urea-hydrogen peroxide (UHP) as oxidizing agents. It was found that the composite has activity similar to 30% H₂O₂ and has a several advantages over UHP such as the fact that silica and H₂O are the only products of the composite decomposition or no contamination by urea or its derivatives occurs; the xerogel is easier to heated by microwave irradiation than UHP and could be used as both an oxidizing agent and as solid support for microwave assisted solvent-free oxidations. Full article