Search Results (749)

As a crucial reactive oxygen species, hydrogen peroxide (H₂O₂) serves as both a physiological regulator and a pathological indicator in human systems. Its urinary concentration has emerged as a valuable biomarker for assessing metabolic disorders and renal function. While conventional colorimetric determination methods predominantly employ enzymatic or nanozyme catalysts, we present an innovative non-catalytic approach utilizing the redox-responsive properties of organic neutral radicals. Specifically, we designed and synthesized a novel radical TTM-DMODPA based on the tris (2,4,6-trichlorophenyl) methyl (TTM) scaffold, which exhibits remarkable optical tunability and oxidative sensitivity. This system enables dual-mode H₂O₂ quantification: (1) UV-vis spectrophotometry (linear range: 2.5–250 μmol/L, LOD: 1.275 μmol/L) and (2) smartphone-based visual analysis (linear range: 2.5–250 μmol/L, LOD: 3.633 μmol/L), the latter being particularly suitable for point-of-care testing. Validation studies using urine samples demonstrated excellent recovery rates (96–104%), confirming the method’s reliability for real-sample applications. Our work establishes a portable, instrument-free platform for urinary H₂O₂ determination, with significant potential in clinical diagnostics and environmental monitoring. Full article

As widely used peroxidase-like nanozymes, Fe-based nanozymes still suffer from an unclear reaction mechanism, which limits their further application. In this work, through alkaline treatment and then the replacement or occupation of strong acid sites by isolated Fe species, porous ZSM-5-confined atomic Fe species nanozymes with separated medium acid sites (Al-OH) and isolated Fe-O₄ sites were prepared. And the structure and the state of Fe-O₄ confined by ZSM-5 were determined by AC-HAADF-STEM, XPS, and XAS. In the oxidation of 3, 3′, 5, 5′-tetramethylbenzidine (TMB) by the hydrogen peroxide (H₂O₂) process, the heterolysis of H₂O₂ to ∙OH mainly occurs at the isolated Fe-O₄ sites, and then the generated ∙OH can spill over to the Al-OH sites to oxidize the adsorbed TMB. The synergistic effect between Fe-O₄ sites and medium acid sites can significantly benefit the catalytic performance of Fe-based nanozymes. Full article

Controlled iron extraction from iron-based sludge (Fe-Sludge) drainage and its use as a Fenton’s reagent is investigated in the current study for eliminating organics from launderette discharge stream. The influences of the iron dosage, hydrogen peroxide concentration, and pH are assessed as treatment factors for their direct impact on the oxidation of organic compounds. Additionally, optimal oxidation conditions are determined using the response surface methodology (RSM) technique, and the ranges of treatment variables are analyzed. The optimum values of a pH of 2.0, Fe sludge concentration of 99 mg/L, and H₂O₂ content of 402 mg/L resulted in optimal organics removal of up to 98%, expressed as Chemical Oxygen Demand (COD) removal. The oxidation efficacy attained from the design is confirmed and the model validation is assessed, and the suggestive model is accepted since it possesses a correlation coefficient of 97.7%. The thermodynamic and kinetic models are also investigated, and the reaction showed that the temperature increases resulted in the oxidation efficiency being reduced. The oxidation efficiency expressed as COD reduction is clearly characterized by first-order reaction kinetics. The thermodynamic characteristics indicated that the oxidation reaction was exothermic and not spontaneous. Full article

Hericium erinaceus, a medicinal macrofungus, is renowned for its potential neuroprotective benefits. Here, we isolated and characterized secondary metabolites from H. erinaceus fruiting bodies and explored their neuroprotective effects and primary mechanisms of action. A novel terpenoid (4) and four known compounds (1, 2, 3, and 5) were identified. Their chemical structures were determined using nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HRMS), and x-ray diffraction (XRD). Bioactivity screening using PC12 cells indicated that (3R,4R)-4-acetyl-3,4-dihydro-6,8-dihydroxy-3-methoxy-5-methyl-1H-2-benzopyran (3) and the terpenoid, (1R,4S,8aS)-1,4-dihydroxy-2,5,5,8a-tetramethyl-1,4,4a,5,6,7,8,8a-octahydronaphthalene-1-carbaldehyde (4), demonstrated protective properties against hydrogen peroxide (H₂O₂)-induced damage. Transcriptomics, network pharmacology, and molecular docking showed that compound 4 counteracted H₂O₂-induced oxidative stress and inflammation by substantially attenuating pro-inflammatory cytokine (IL-1β, IL-6) expression, downregulating pro-oxidant factors (Aoc3, Dusp3), and decreasing reactive oxygen species levels, while boosting superoxide dismutase activity. Compound 4 exerted neuroprotective effects via the NF-κB pathway. H. erinaceus represents a valuable natural reservoir of bioactive compounds for treating and preventing neurodegenerative diseases. Full article

The kinetics of the depolymerization of natural rubber (NR) to hydroxyl-terminated natural rubber (HTNR) by hydrogen peroxide (H₂O₂) in the presence of a Fenton catalyst within an acidic milieu and under ultraviolet radiation has been rigorously examined utilizing infrared spectroscopy to determine the alterations in molar mass and the functional characteristics. The kinetic model was analyzed in accordance with the elementary reaction, encompassing the following mechanisms: the interaction between hydroxyl radicals and NR, producing radical NR and hydroxylated NR; the reaction wherein radical NR and hydroxyl radicals yield hydroxylated NR; and the subsequent reaction of hydroxylated NR with hydroxyl radicals producing lower radical NR, hydroxylated terminated NR, radical NR, and hydroxylated NR. The conversion of the NR polymer and the total hydroxyl content were discerned at the absorption bands of the CH₂-CH₂ and OH groups located at 850 cm⁻¹ and 3400 cm⁻¹, respectively. The absorption peak at 1850 cm⁻¹ attributed to CH₃ was employed as the reference group for calibration. The influence of the temperature on the depolymerization process conformed to the Arrhenius equation, characterized by activation energies of 750 K and 1200 K. The impact of the H₂O₂/Fenton ratio on the depolymerization process follows a power law with power coefficients of 1.97 and 1.82. Full article

A total of 1.6 million tons of personal protective equipment (PPE) waste has been generated daily since 2019 and this production has not abated since that time. Within PPEs, isolation gowns make up the largest percentage by weight of landfill waste. This study aimed to evaluate the effectiveness of rapid, reproducible disinfection protocols to help facilitate safe reuse and minimize risks from microbial contamination. Disinfection of isolation gowns via fogging with hydrogen peroxide (HP) and hypochlorous acid (HC) were evaluated in the present study compared to standard ethylene oxide (EO) sterilization. This study was conducted at VCA West Coast Specialty and Emergency Animal Hospital in the United States. Ten isolation gowns (control) were cultured on tryptic soy agar contact plates in 10 predetermined areas to determine microbial load and morphology/types on non-sterile gowns before use. Following this, 10 gowns were fogged with 12% HP, and then once drying was complete, they were cultured in the predetermined areas for microbial load and morphology/types. This procedure was repeated with another set of 10 gowns fogged with 500 ppm HC. Lastly, 10 gowns were sterilized with EO using standard protocol and cultures were performed similarly. Median CFU (colony-forming unit) counts at 48 h for control, EO, HP, and HC were 4.5, 0, 0, and 0; at 72 h, they were 107, 0, 0, and 0, respectively. No significant difference was noted between the disinfection groups; post hoc pairwise analysis showed that the CFU counts for the disinfection groups were significantly lower than those for the control. The median percent reduction at 48 h for EO, HP, and HC was 100, 100, and 100; at 72 h, it was 100, 100, and 100, respectively. No significant difference was detected among the groups. The median number of microbe types for control, EO, HP, and HC was 2.5, 0, 0, and 0; there was no difference between the disinfection groups, but the number of microbe types was significantly higher for the control than for the disinfection groups. EO is environmentally toxic, expensive, and carcinogenic; it requires prolonged disinfection cycle times, expensive equipment, and trained personnel. This study suggests that HP and HC provide a cost-effective, relatively nontoxic, environmentally safe, and comparatively short disinfection time option for the disinfection and reuse of isolation gowns that does not require trained personnel or specialized equipment. Full article

Strong UV-B radiation is one of the main climatic characteristics of the Qinghai–Tibet Plateau. Plants grown on the Tibetan Plateau are exposed to high-intensity UV radiation and therefore require effective mechanisms to adapt to these stresses. However, little attention has been paid to the response of grass–endophytic fungi symbiosis to UV-B radiation in this area. In this study, we investigated the relationship between Epichloë gansuensis and the growth and antioxidant responses of Achnatherum inebrians seedlings exposed to different UV-B doses, aiming to evaluate the growth and antioxidant capacity of A. inebrians seedlings under UV-B stress. The plant height, tillers, biomass, electrical conductivity, soluble sugars, malondialdehyde (MDA), proline, hydrogen peroxide (H₂O₂), superoxide dismutase (SOD), polyphenol oxidase (POD), and catalase (CAT) of A. inebrians seedlings were determined under different intensities of UV-B radiation treatments. The results showed that, with the increase in UV-B radiation intensity, the plant height, tiller and biomass of A. inebrians seedlings showed a decreasing trend, the electrical conductivity increased, malondialdehyde content increased, soluble sugar and proline content decreased, SOD, POD, and CAT activities showed a decreasing trend, and the content of H₂O₂ increased, which means that the UV-B radiation was able to inhibit the morphogenesis and aggravate the membrane lipid peroxidation of A. inebrians seedlings. The tolerance of the A. inebrians–E. gansuensis symbiont to UV-B may enable it to have a high infection rate on the Qinghai–Tibet Plateau. Full article

The fig (Ficus carica L.) is one of the oldest fruit crops cultivated in arid and semi-arid regions, valued for both its nutritional and economic importance; thus, ensuring sustainable fig production under climate change conditions is very important, as water scarcity increasingly affects fruit quality and production. Selecting and preserving resilient varieties among traditional varieties, representing centuries of local adaptation, is a vital strategy for addressing the challenges driven by climate change. In this context, this study assessed the physiological and biochemical parameters of the leaves of four fig landrace varieties (Fassi, Ghouddane, Nabout, and Ounq Hmam) grown in three different Mediterranean transitional zones of northern Morocco (Chefchaouen, Taounate, and Taza), during a single timepoint assessment conducted in late August 2023. The combined effects of location, variety, and their interactions on chlorophyll fluorescence (F_v/F_m), Soil Plant Analysis Development (SPAD) index, total chlorophyll content (ChlT), canopy temperature depression (CTD), proline content, protein content, total soluble sugar (TSS), hydrogen peroxide (H₂O₂), and malondialdehyde (MDA) were determined. Significant variation was observed among varieties and locations, with the location effect being observed for proline content, protein content, TSS, CTD, and ChlT, while variety had a stronger influence on SPAD, F_v/F_m, H₂O₂, and MDA. The results showed that Nabout and Ounq Hmam varieties had the greatest photosynthetic efficiency, as indicated by their elevated SPAD index, ChlT, and F_v/F_m values, and showed lower sensitivity to oxidative stress (low proline content, H₂O₂, and MDA levels). In contrast, Ghouddane and Fassi displayed better stress tolerance, presenting higher levels of oxidative stress markers. Among locations, Chefchaouen showed the highest protein, TSS, H₂O₂, and MDA levels, reflecting active stress tolerance mechanisms. These variations were confirmed by principal component analysis, which revealed a clear separation between photosynthetically efficient varieties (Nabout and Ounq Hmam) and stress-tolerant varieties (Ghouddane and Fassi). More than a conventional crop physiology study, this work highlights the adaptive strategies in traditional Mediterranean fig germplasm that could be crucial for climate change adaptation. While our findings are limited to a single season, they offer valuable, practical insights that can inform grower decision-making in the near term, especially when considered alongside local knowledge and additional research. Full article

Chitosan, a naturally occurring alkaline polysaccharide with excellent biocompatibility, non-toxicity, and renewability, has the ability to undergo cross-linking reactions with polyphenolic compounds. In this study, chitosan-encapsulated green tea extract microsphere resin (CS-GTEMR) was successfully prepared using chitosan and green tea extract via reversed-phase suspension cross-linking polymerization. The structural characterization of CS-GTEMR was conducted using Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). Additionally, its physical properties, swelling behavior, polyphenol content, and antioxidant activities were investigated. The results indicate that CS-GTEMR consists of reddish-brown microspheres with a smooth surface and dense pores. The study found that the total content of polyphenolic compounds encapsulated in CS-GTEMR was 50.485 ± 0.840 μg/g. The characteristic absorption peak of phenolic hydroxyl groups appeared in the FTIR spectrum, suggesting that the polyphenolic compounds had been successfully encapsulated within the CS-GTEMR. The equilibrium swelling ratio of CS-GTEMR was determined to be 229.7%, indicating their suitability for use in solutions with a pH range of 1–13. In simulated gastric and intestinal fluids, the release rates of polyphenolic compounds from CS-GTEMR were 24.934% and 3.375%, respectively, indicating that CS-GTEMR can exert a sustained-release effect on polyphenolic compounds. CS-GTEMR demonstrated antioxidant activities such as scavenging DPPH radicals, superoxide anion radicals, hydroxyl radicals, and hydrogen peroxide, as well as exhibiting iron-reducing and molybdenum-reducing powers. With its high mechanical strength, acid resistance, and organic solvent resistance, CS-GTEMR can protect polyphenolic compounds from damage. Therefore, CS-GTEMR can be utilized as a natural antioxidant or preventive agent in food, expanding the application scope of green tea extracts. Full article

Epigeal cotyledons with excised embryonic axes are often used as a model system to study the processes of cell division and expansion. These processes are regulated by diverse phytohormones and signaling molecules. Phytohormones modulate antioxidant defense systems and interact with reactive oxygen species (ROS) to synchronize normal plant cell growth. This study provides new information concerning alterations in enzymatic antioxidants linked to the production and scavenging of ROS in excised epigeal cotyledons of zucchini grown on solutions of methyl jasmonate (MeJA) and cytokinins (CKs)—N⁶-benzyl adenine and N₁-(2-chloropyridin-4-yl)-N₂-phenylurea—in the presence or absence of light under laboratory conditions. The cotyledon material was used to determine the dynamics of selected biochemical parameters starting from the 2nd to the 6th day of incubation. In general, our results revealed that exogenous MeJA caused a reduction in the content of hydrogen peroxide (H₂O₂) and free proline, as well as in the activity of superoxide dismutase (SOD), guaiacol peroxidase (POX) and catalase (CAT) in dark-grown cotyledons. Applied alone, both cytokinins increased most of the parameters studied, except proline and protein levels. However, when MeJA was combined with CKs, it acted in a diverse manner, ranging from antagonistic to synergistic depending on the cytokinin type, parameter measured and light regime. Similar alterations were also found in the levels of leaf pigments in the cotyledons grown under light conditions. In general, the changes in the antioxidant enzyme activities due to light were more intense than those observed in dark-grown cotyledons. The data obtained show, for the first time, the involvement of the hormonal interplay between MeJA and CKs on the biochemical changes in antioxidant defense during cotyledon growth under different light conditions. Full article

The endoplasmic reticulum mediates essential processes such as protein folding, transport, and post-translational modifications. Disruptions in endoplasmic reticulum function can lead to the accumulation of unfolded or misfolded proteins, initiating endoplasmic reticulum stress. This stress activates the unfolded protein response, a multifaceted signaling pathway aimed at restoring proteostasis, which is crucial for cellular survival and fate determination. This review summarizes the current knowledge of three major branches of the unfolded protein response: the IRE1, PERK, and ATF6 signaling pathways. A key novel component in endoplasmic reticulum stress adaptation is the redox-sensitive enzyme glutathione peroxidase 8 (GPX8), which plays a dual role in detoxifying hydrogen peroxide and supporting proper protein folding. By connecting unfolded protein response branches, GPX8 reduces oxidative damage while maintaining redox homeostasis, emphasizing its importance in endoplasmic reticulum stability. Furthermore, plant glutathione peroxidases exhibit parallel functions in endoplasmic reticulum redox homeostasis and unfolded protein response activation, highlighting the evolutionary conservation of this protective mechanism across kingdoms. Understanding the intricate relationship between GPX8, endoplasmic reticulum stress, and unfolded protein response signaling provides novel insights into therapeutic strategies for diseases characterized by protein folding defects and oxidative stress. Full article

Background: The Er:YAG laser has gained attention in dentistry for its potential to enhance microbial disinfection through targeted photothermal and photoacoustic mechanisms. Objective: This systematic review aimed to evaluate the antibacterial and bactericidal efficacy of Er:YAG laser therapy across clinically relevant oral pathogens in in vitro models. Methods: Following the PRISMA 2020 guidelines, a systematic search of PubMed, Embase, Scopus, and the Cochrane Library was conducted for studies published between 2015 and 2025. The review protocol was registered with PROSPERO (CRD420251031368). Eligibility criteria included in vitro or animal studies assessing the bactericidal effects of the Er:YAG laser on oral bacteria or fungi, either alone or in combination with chemical disinfectants. Study selection, data extraction, and quality assessment were conducted independently by multiple reviewers. Results: Ten in vitro studies met inclusion criteria. The Er:YAG laser demonstrated significant antibacterial effects against Enterococcus faecalis, Streptococcus mutans, Porphyromonas gingivalis, Candida albicans, and other species. Greater bacterial reduction was consistently observed when the laser was combined with adjunctive irrigants such as sodium hypochlorite or hydrogen peroxide. The laser was effective in reducing biofilm biomass and viable counts, particularly in complex anatomical settings. Most studies were rated as low risk of bias. Conclusions: Er:YAG laser therapy is a promising adjunctive tool for microbial disinfection in dentistry, particularly in challenging anatomical sites. Further well-designed in vivo and clinical studies are needed to confirm its efficacy and determine optimal treatment parameters. Full article

In rocketry today, conventional hypergolic propellant combinations typically use hydrazine-derived fuels and oxidizers based on nitrogen tetroxide. Due to their high toxicity and consequently expensive handling, safer alternatives, so-called “green hypergolics”, are currently being developed. The ionic liquid-based fuels [EMIM][SCN], HIP_11 and HIM_30, paired with highly concentrated hydrogen peroxide as an oxidizer, are three candidates for such green hypergolics, which are currently under research at the German Aerospace Center (DLR). These combinations have been shown to exhibit reliable hypergolic ignition. For a better understanding of the reaction process and to assess the risks in working with these propellants, it is desirable to determine their combustion products. A test setup was designed to extract the gaseous combustion products from hypergolic drop tests. The gas samples were analyzed using Fourier-transform infrared spectroscopy and the gaseous combustion products were determined from the infrared spectra. Additional tests with varied oxidizer concentration or alternative fuels were conducted to further investigate detailed aspects of the findings. It was concluded that [EMIM][SCN], HIP_11 and HIM_30 produce very similar sets of combustion products with hydrogen peroxide, including water vapor, carbon dioxide, carbon monoxide, hydrogen cyanide and sulfur dioxide. Finally, the combustion products were compared to the substances produced when thermally decomposing the fuels. This confirmed that the previously detected substances were caused by a reaction between hydrogen peroxide and the fuels, rather than by their thermal decomposition due to heating. Full article

This study highlights the significant environmental and health risks associated with heavy metal contamination (As, Cd, Cr, and Pb) in Oreochromis niloticus (Nile tilapia) from two locations: the Khon Kaen municipal landfill (study site) and the Thapra commercial fish farm (reference site). It also evaluates potential human health risks and investigates genotoxicity and oxidative stress markers, including malondialdehyde, hydrogen peroxide (H₂O₂), catalase (CAT), and superoxide dismutase (SOD) in fish. Heavy metal concentrations were analyzed using inductively coupled plasma optical emission spectrometry. To determine genetic differentiation, inter-simple sequence repeats with dendrogram construction and genomic template stability (%GTS) were applied. The results showed that the average concentrations of As, Cd, Cr, and Pb in water samples were 0.0848, 0.536, 1.23, and 0.73 mg/L, respectively. These values exceeded safety limits, and the average Cd in sediment (1.162 mg/kg) was above regulatory thresholds. In fish muscle, the average metal concentrations (mg/kg) followed the order Cr (1.83) > Pb (0.69) > Cd (0.096) > As (0.0758), with Pb exceeding food quality standards. The bioaccumulation factor ranked as Cr > Pb > As > Cd. Health risk assessments, including health risk index and carcinogenic risk, suggested Pb contamination poses significant health risks through fish consumption. From dendrogram results, the %GTS of O. niloticus from the landfill and reference sites were 46.34 to 71.67% and 87.34 to 96.00%, respectively. This suggests that fish from the landfill site exhibited greater genetic diversity compared to those from the reference site. Specific oxidative stress markers revealed higher levels of H₂O₂ and significantly lower activities of CAT and SOD in landfill O. niloticus than in the reference site. These results emphasize the urgent need for environmental monitoring, stricter pollution controls, and improved waste management strategies to protect aquatic ecosystems and human health. Full article

Metal complexes of endogenous metals, such as iron, copper, and zinc, offer a biocompatible, cost-effective, and eco-friendly alternative to heavy metals for drug design. This study presents the synthesis, structural characterization, and evaluation of the biological activity of eight novel iron(III) complexes with substituted salicylaldehydes as ligands. The characterization of the complexes involved spectroscopic and physicochemical methods. The structures of two complexes were determined using single-crystal X-ray crystallography. The biological studies of the complexes focused on the interaction of calf-thymus DNA, the (photo)cleavage of pBR322 plasmid DNA (pDNA), the affinity for bovine and human serum albumins, and the antioxidant activity. The complexes interacted with calf-thymus DNA via intercalation with high DNA-binding constants. The complexes exhibited high pDNA-cleavage ability, which is significantly enhanced upon exposure to UVA or UVB irradiation. The complexes can bind tightly and reversibly to both serum albumins, and their binding locations were identified. Finally, the complexes showed moderate ability to scavenge 1,1-diphenyl-picrylhydrazyl and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radicals with a high ability to reduce hydrogen peroxide. Full article