Search Results (2,495)

To demonstrate the applicability of the “dynamic self-vulcanization of bifunctional monomers” strategy for toughening polylactic acid (PLA), hydroxylated oleic acid (HOA) was synthesized via UV-initiated thiol–ene click chemistry, using oleic acid as the starting material. In the presence of an excess molar quantity of hexamethylene diisocyanate (HDI), the dynamic self-vulcanization of bifunctional monomers was employed to design PLA blends featuring extraordinary impact toughness. During the one-pot melt compounding, in situ formation and self-crosslinking of flexible poly(urethane-co-amide) (HPUA) toughening phase, together with its reactive compatibilization with the PLA matrix, were simultaneously accomplished. The aggregation of the HPUA domains enabled the morphological transformation of the PLA blend from a sea-island structure to a partially or fully bi-continuous one. At HPUA contents of 20 wt% or higher, the blend exhibited a bi-continuous morphology with a crosslinked HPUA network, attaining a notched impact strength exceeding 110 kJ/m² and an elongation at break above 200%. In particular, when the HPUA content reached 20 wt%, the resulting PLA blend exhibited optimal impact toughness, with a notched IS of 132.1 kJ/m² (30.7 times that of neat PLA). The primary toughening mechanism was determined to be the internal cavitation of the HPUA domains, which subsequently initiates the yielding of the surrounding PLA matrix. This study proposes an applicable and facile method for fabricating polymer materials that possess excellent impact toughness. Full article

Imidazo [2,1-b][1,3]thiazines and their fused analogues are an important class of nitrogen- and sulfur-containing heterocycles that exhibit a wide range of biological activities. Herein, a straightforward synthetic protocol for 2,3-dihydro-5H-imidazo [2,1-b][1,3]thiazin-5-one under catalyst-free, mild conditions is reported. The title compound was obtained via the regioselective heterocyclization of 4,5-dihydro-1H-imidazole-2-thiol with alkyl propiolates (methyl or ethyl) by stirring at room temperature for 24 h in ethanol. The structure of the synthesized compound and the regioselectivity of the reaction were confirmed through a combination of ¹H, ¹³C, and 2D NMR experiments (HSQC, HMBC), LC-MS, and elemental analysis. The synthesized title compound is of interest to synthetic organic and medicinal chemistry as a starting building block with potential for further core modification. Full article

Oxidative stress plays an important role in systemic lupus erythematosus (SLE). To elucidate whether it is already present in early phases, we investigate oxidative stress-related genes in incomplete SLE (iSLE) and quiescent SLE (qSLE, inactive disease), as well as the effect of nuclear factor erythroid-derived 2-like 2 (NRF2) activators on NRF2-related genes in peripheral blood mononuclear cells (PBMCs) and HaCaT keratinocytes. In total, 28 qSLE patients, 29 iSLE patients and 21 age- and sex-matched healthy controls (HCs) were included. Serum free thiols, reactive oxygen species (ROS) levels and NRF2-related antioxidant gene expression were measured. Furthermore, PBMCs and HaCaT keratinocytes were treated with the NRF2 activators sulforaphane (SFN) and dimethyl fumarate (DMF) in vitro to assess expression of antioxidant genes. Finally, NRF2 and Heme oxygenase-1 (HMOX1) proteins in non-sun-exposed skin sections were assessed. Thiols were significantly lower in qSLE patients compared to HCs. In whole blood, Kelch-like ECH-associating protein 1 (KEAP1) and catalase (CAT) mRNA levels were significantly reduced in iSLE and qSLE. Treatment with SFN or DMF in PBMCs upregulated HMOX1 and NAD(P)H quinone dehydrogenase-1 (NQO1) mRNA expression and downregulated CAT expression. In HaCaT cells, mRNA expression of HMOX1, NQO1 and thioredoxin was upregulated. There were no differences in protein expression of NRF2 and HMOX1 in skin tissues. In conclusion, in qSLE patients, oxidative stress is elevated, while antioxidant capacity is decreased. A similar trend, although not significant, is seen in iSLE patients, which indicates that redox imbalances are already present in early phases, but not as obvious as in established SLE. NRF2 activators upregulate antioxidant gene expression in PBMCs and HaCaT cells, highlighting their potential role to modulate oxidative stress pathways in SLE. Full article

Harvest timing is an important management factor associated with the volatile composition of wine. This one-vintage study investigated selected free aroma-related volatile compounds in Blaufränkisch and Pinot Noir wines produced under standardised microvinification from grapes harvested at early, standard and late maturity-related stages in four commercial vineyards. Free volatile polyfunctional thiols, six-carbon (C₆) alcohols, free monoterpenes, rotundone and free 13-carbon (C₁₃) norisoprenoids were quantified using gas chromatographic methods, and data were evaluated using exploratory univariate and multivariate statistics. Harvest-stage responses were compound-specific and depended on the investigated grape-variety/regional sample sets. The concentration of 1-hexanol generally decreased with advancing harvest stage, whereas 3-sulfanylhexan-1-ol (3-SH) tended to increase across several vineyard origins. An exploratory pooled correlation between 1-hexanol and 3-SH was weakly negative, indicating only a limited association between the two compounds in bottled wines. Free monoterpenes and free C₁₃-norisoprenoids showed non-linear, compound-dependent patterns, while rotundone showed no consistent overall harvest-stage response. Principal component analysis (PCA) separated the wines mainly according to grape-material background, with additional harvest-stage-related structuring. Overall, under the specific conditions of this one-vintage study, operationally defined maturity-related harvest timing was associated with compound- and background-dependent changes in selected free aroma-related volatile compounds in the investigated red wines. Full article

Oxidative stress is closely associated with mitochondrial dysfunction and contributes to the development of several human diseases. Among antioxidant compounds, ASC and NAC are widely used for their cytoprotective and redox-regulating properties; however, their direct effects on specific aspects of mitochondrial bioenergetics are only partially characterized. In the present study, we investigated the effects of ASC and NAC, individually and combined, on Mg²⁺-dependent F₁F_O-ATPase hydrolysis, mitochondrial free thiol content and respiration in isolated swine heart mitochondria. ASC significantly stimulated F₁F_O-ATPase activity in a concentration-dependent manner, whereas kinetic analysis indicated a mixed uncompetitive activation mechanism. In contrast, NAC alone did not significantly affect F₁F_O-ATPase activity but abolished the stimulatory effect of ASC when the two compounds were combined. Both ASC and NAC increased mitochondrial free thiol content, although no change was observed under combined treatment conditions. Mitochondrial oxygen consumption analysis revealed substrate-dependent effects of the two antioxidants on electron transport. Overall, ASC and NAC exerted distinct direct actions on isolated mitochondria, and their combination did not produce additive or synergistic effects. These findings provide new insights into the direct modulation of mitochondrial function by antioxidant compounds and may contribute to expanding understanding of their potential therapeutic and dietary supplement applications, particularly when combined. Full article

Ulcerative colitis is characterized by inflammation, oxidative stress, and excessive free radical production. This study investigated the antioxidant, anti-inflammatory, and protective effects of N-acetylcysteine (NAC), Tiron, and their fixed-ratio combination in acetic acid-induced colitis. An integrated approach was used, combining ligand–ligand docking, acellular antioxidant and protein-denaturation assays, and an in vivo model in male Wistar rats. Colitis was induced by intrarectal administration of 3% acetic acid after 14 days of intraperitoneal pretreatment with NAC, Tiron, or NAC–Tiron. Docking analysis suggested physicochemical compatibility through non-covalent interactions. In vitro, NAC, Tiron, and their combination showed antioxidant and anti-denaturation activities. NAC–Tiron displayed greater activity than the individual compounds in selected endpoints, particularly 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, but did not consistently outperform them across the other assays. In vivo, NAC, Tiron, and NAC–Tiron attenuated macroscopic and histological colonic damage, reduced inflammatory cell infiltration and edema, decreased lipid peroxidation and protein carbonylation, and helped preserve superoxide dismutase (SOD) activity, reduced glutathione (GSH), and total thiols. The treatments also attenuated increases in C-reactive protein (CRP) and free iron without evident worsening of the measured systemic biochemical parameters. Overall, these findings provide an exploratory proof of concept for fixed-ratio NAC–Tiron co-administration but do not establish pharmacological synergy or superiority over standard therapies. Full article

In this study, two epoxy-functional polysiloxanes were synthesized and applied for cotton hydrophobization using two modification routes: direct reactive deposition and thiol-crosslinking on the fiber surface. PS1 contained epoxy groups, whereas PS2 contained both epoxy groups and alkyl chains. The modified fabrics were characterized by add-on measurements, FT-IR spectroscopy, SEM-EDS, SEM imaging, washing tests, and static water contact angle measurements. Both modification strategies enabled the formation of polysiloxane-based layers on cotton, as confirmed by the presence of silicon in all modified samples and sulfur in thiol-crosslinked samples. SEM images showed continuous and relatively uniform coatings without visible fiber damage. All modified fabrics became hydrophobic and retained their properties after washing. Thiol-crosslinking was more effective than direct reactive deposition, giving WCA values up to 144°. PS1 provided stable hydrophobicity regardless of thiol type or concentration, while PS2 benefited from higher modifier concentration and the use of tetrafunctional thiol. The results show that epoxy-functional polysiloxanes, especially when crosslinked with multifunctional thiols, are effective modifiers for producing washable hydrophobic cotton fabrics. Full article

Background: Polymerization shrinkage stress remains one of the main limitations of methacrylate-based dental resin composites, as it may lead to marginal gap formation, interfacial debonding, and long-term restoration failure. In recent years, numerous experimental monomers and alternative polymerization strategies have been proposed to mitigate stress development during polymer network formation. This scoping review aimed to map and summarize experimental and modified monomer systems investigated for reducing polymerization shrinkage stress in dental methacrylate-based composites. Methods: A comprehensive literature search was conducted in PubMed/MEDLINE, Scopus, Web of Science Core Collection, Embase, and Google Scholar to identify relevant studies published between 2010 and 2025. The search strategy combined terms related to dental resins, polymerization shrinkage, shrinkage stress, and experimental monomers (1678 papers found). After duplicate removal and screening of titles and abstracts, potentially relevant articles were assessed for full-text eligibility according to predefined inclusion criteria. In vitro studies investigating experimental monomers or modified resin systems with reported polymerization shrinkage stress measurements were included. Data extraction focused on monomer composition, chemical strategy for stress reduction, measurement methods, and reported shrinkage stress values. Results: A total of 33 studies met the eligibility criteria and were included in the qualitative synthesis. The reviewed studies investigated a wide range of molecular strategies, including thiol–ene and thiourethane chemistries, addition–fragmentation chain transfer (AFCT) networks, ring-opening or expanding monomers, high-molecular-weight dimethacrylates, ether-based monomers, and alternative reactive diluents. Reported polymerization shrinkage stress outcomes varied widely across studies because of differences in testing methods, specimen geometry, system compliance, curing protocols, reporting units, and control materials. Therefore, the results were synthesized descriptively, with emphasis on within-study comparisons between experimental systems and their respective controls rather than on direct numerical comparisons across studies. Thiol-based systems and adaptive polymerization mechanisms consistently demonstrated the greatest reductions in shrinkage stress compared with conventional dimethacrylate resin matrices. Conclusions: Experimental monomer design represents a promising strategy for controlling polymerization shrinkage stress in dental composites. Chemical approaches that modify polymerization mechanisms or network architecture may significantly reduce stress development during curing. Further studies are required to evaluate the long-term chemical, physical, and mechanical stability, as well as the clinical applicability, of these experimental and modified resin systems. Full article

Background/Objectives: Chronic complications of diabetes mellitus are closely associated with increased oxidative stress and the formation of advanced glycation end products (AGEs). This study aimed to investigate the antioxidant and antiglycation potential of hesperetin-7-O-glucoside (HCD) and diosmetin-7-O-glucoside (DCD) formulations complexed with cyclodextrins, using in vitro and in silico experimental models to evaluate their efficacy in mitigating hyperglycemia-induced molecular damage. Methods: Antioxidant activity was assessed using chemical and erythrocyte-based oxidative stress models, whereas antiglycation activity was evaluated in BSA–fructose, BSA–methylglyoxal, and arginine–methylglyoxal models. Results: Both formulations showed measurable antioxidant effects, with concentration-dependent behavior observed in some of the evaluated assays. In the DPPH assay, HCD and DCD achieved maximum inhibition values of 30.71% and 26.61%, respectively. Furthermore, DCD exhibited higher total antioxidant capacity (102.80 µg vitamin C equivalents/mL) and nitric oxide scavenging activity (37.89%) than HCD. In a cellular model, both formulations (200 µg/mL) significantly reduced AAPH-induced hemolysis, with DCD providing superior protection (7.05% vs. 16.63% for HCD). Under oxidative stress induced by high glucose concentration in erythrocytes, HCD and DCD reduced non-protein thiol levels, and HCD significantly increased catalase enzyme activity. Regarding antiglycation activity, DCD demonstrated superior efficacy relative to HCD in the BSA-fructose system, achieving 43.23% inhibition. DCD also displayed concentration-dependent inhibition of fructosamine formation (up to 47.99%) and BSA glycation by methylglyoxal (up to 45.20%). Both formulations significantly reduced carbonylated protein levels and preserved free thiol groups. In the arginine–methylglyoxal model, DCD and HCD reached 44.03% and 48.82% inhibition, respectively. Molecular docking revealed high binding affinity of both flavonoids to the protein active site (−9.00 kcal/mol for hesperetin-7-O-glucoside and −9.04 kcal/mol for diosmetin-7-O-glucoside), suggesting a structural protective role. Conclusions: The HCD and DCD formulations demonstrated antioxidant and antiglycation activities that may contribute to attenuating molecular alterations associated with chronic hyperglycemia through complementary mechanisms, including antioxidant effects, protection against protein carbonylation, and inhibition of glycation. While these findings highlight the potential of the evaluated formulations, additional mechanistic and in vivo studies are required to establish their pharmacological applicability. Full article

To develop self-healing polyurethane materials with high transparency and superior mechanical performance, in this work, the poly(thiourethane) elastomers were prepared by incorporating the dynamic thiourethane bonds via thiol–isocyanate click reaction, followed by the addition of 1-(3-aminopropyl)imidazole (IZ), 3-hydroxypyridine (HP), and 2,4-diamino-6-hydroxypyrimidine (HPM) as ligands to produce three different polyurethane networks (named PTU-IZ, PTU-HP, and PTU-HPM). Zinc chloride (ZnCl₂) was further introduced to construct metal-coordinated crosslinking networks, recorded as PTU-IZ-Zn, PTU-HP-Zn, and PTU-HPM-Zn, respectively. The effects of ligands and Zn²⁺ coordination on the materials’ optical transmittance, mechanical properties, self-healing capability, and reprocessability were systematically investigated. The results demonstrate that HPM and Zn²⁺ will facilitate the formation of more effective crosslinking, which significantly enhances the mechanical properties of PTU-HPM from 4.61 MPa up to 9.04 MPa (PTU-HPM-Zn), while maintaining high transparency (89.0% light transmittance at 650 nm). Self-healing tests reveal that the PTU-HPM-Zn scratches can fully repair within 4 h at 70 °C. Reprocessability tests demonstrate that the internal crosslinked network of the material undergoes reversible dissociation, enabling a topological transition from a crosslinked to a linear structure and thereby imparting excellent thermal reprocessability. This study provides novel insights for the design and fabrication of high-performance transparent self-healing polyurethane materials. Full article

Redox homeostasis is driven by the ratio of the concentrations of cellular redox couples. The aim of this study was to reduce 2GSH/GSSG turnover in an ex vivo ileum by the irreversible inhibition of glutathione reductase (GR) activity (by BCNU) and evaluate its effects on contractility, antioxidant enzyme activity, and thiol levels. Increasing concentrations of BCNU as well as a single EC50 BCNU dose significantly reduced both contraction amplitude and GR activity. The addition of cumulative doses of both GSH and GSSG after EC50 BCNU caused further dose-dependent amplitude reduction, but turned GR activity to control levels and reduced CuZn-superoxide dismutase activity; cumulative doses of GSH also decreased catalase activity. Both GSH and GSSG cumulative doses decreased the contractility of non-treated control ileum in a dose-dependent manner, while GSH also increased glutathione peroxidase (GPx) activity. The correlation analysis showed a negative relationship between contractility and non-protein thiols, and positive correlations between catalase and GPx activities in BCNU treated ileum, as well as between GPx and non-protein thiols in solvent controls. The results present a framework for how glutathione turnover and ileum contractility are linked. Full article

Ascorbate (AsA), or vitamin C, is a central redox metabolite that functions as an antioxidant, enzyme cofactor, and electron donor. Its cellular function depends not only on biosynthesis or dietary uptake, but also on rapid recycling from its oxidized forms, monodehydroascorbate (MDHA) and dehydroascorbate (DHA). This requirement is especially evident in high-demand systems such as plant chloroplasts, which face continuous photosynthetic reactive oxygen species (ROS) production under illumination, and human neutrophils, which accumulate millimolar ascorbate to withstand NADPH oxidase-driven oxidative bursts in pathogen defense. Here, we revisit ascorbate recycling from a sulfur-centered perspective. Historical studies of plant, animal, and solution-chemistry pathways show that many DHA-reducing systems converge on sulfur chemistry, including glutathione (GSH), cysteine-dependent enzymes, H₂S, and modified thiols. We propose that ascorbate recycling is organized as a multilayered system in which nonenzymatic reactions are accelerated by enzymes, localized within cellular or extracellular compartments, and integrated with broader NAD(P)H-, glutathione-, sulfur-, and diet-dependent redox networks. Within this framework, the AsA/DHA couple can be viewed as a molecular redox capacitor that buffers transient oxidative pressure. Reactive sulfur species (RSS), including persulfides and polysulfides, represent chemically plausible but experimentally unresolved contributors to DHA reduction. Full article

Melatonin is a naturally occurring compound that regulates many aspects of plant growth and development. Recently, its stress-protective potential has been extensively studied. This study investigates the effect of exogenous melatonin on non-enzymatic antioxidants, gene expression, and activity of key antioxidant enzymes in young winter wheat plants subjected to 5 days of drought. Melatonin was root-supplemented 24 h before or after the stress. The parameters were analyzed in the leaves of two Bulgarian cultivars at the end of drought, and after recovery. Drought activated both enzymatic and non-enzymatic antioxidant defense in both cultivars, with distinct responses reflecting their tolerance. The drought-tolerant cv. Gines showed marked increase in total phenolics, thiol containing compounds, catalase (CAT) and glutathione reductase (GR) activities, and catalase (CATA, CAT3) and class III peroxidase (POX2) transcript levels. The less tolerant cv. Fermer exhibited more limited induction, primarily involving CATA, CAT3 and GR transcripts and the glutathione pool. Melatonin pre-treatment generally attenuated drought-induced antioxidant responses. This effect was more pronounced in cv. Fermer, where the most drought-responsive parameters were also the most alleviated by melatonin, whereas in cv. Gines only CATA expression, and CAT and GR activities were significantly influenced, suggesting cultivar-dependent modulation of antioxidant systems by melatonin. During recovery, both pre- and post-drought melatonin applications produced comparable effects on the antioxidant defense. The post-treatment selectively enhanced the studied transcripts in a cultivar-specific manner. Full article

Diabetic kidney disease (DKD) is characterized by progressive renal dysfunction driven by oxidative stress, inflammation, and hemodynamic alterations. Photobiomodulation (PBM) has emerged as a potential non-invasive therapeutic strategy targeting these pathways. To evaluate the effects of PBM on kidney function, hemodynamics, oxidative stress, and inflammatory profile in a rat model of DKD. Adult male Wistar rats were randomly assigned to four groups: control (Ct), Ct + PBM, DKD, and DKD + PBM. Diabetes was induced by streptozotocin (60 mg/kg, i.v.). PBM (808 nm, 100 mW) was applied transcutaneously (3 J per point; 30.48 J/cm²), bilaterally over the renal region, three times per week for six weeks. Kidney function (inulin clearance, serum creatinine, albuminuria), hemodynamics (mean arterial pressure, renal blood flow, renal vascular resistance), oxidative stress markers (urinary H₂O₂, NOx, thiols, Nrf2), and IL-1β levels were evaluated. DKD animals showed impaired kidney function, increased oxidative stress, and elevated inflammatory markers. PBM treatment significantly improved inulin clearance, reduced albuminuria and serum creatinine, increased renal blood flow, and decreased mean arterial pressure and vascular resistance. Oxidative stress markers and IL-1β levels were attenuated, with partial restoration of antioxidant capacity. No significant histological differences were observed. PBM improves kidney function and modulates redox and inflammatory pathways in experimental DKD, supporting its potential as a non-invasive adjunct therapy. Full article

Ultrasound-assisted xylose glycation is found to be an effective method to improve the gel properties, functional properties and structural characteristics of meat proteins, and to some extent minimize the generation of protein cross-linking. The effects of dual-frequency ultrasound-assisted (20/25, 20/28, 25/28, 20/40, 25/40, 28/40, 28/68, and 40/68 kHz) xylose glycation on beef myofibrillar proteins (MPs) were evaluated in the study. Compared with the control, dual-frequency ultrasound promoted glycation in a frequency-dependent manner. The highest grafting degree was observed at 20/25 and 25/40 kHz, reaching 37.05% and 38.47%, respectively. For gel-type applications, 25/28 kHz ultrasound provided the most balanced performance. It reduced cooking loss from 79.80% to 73.77%, increased hardness from 1388.18 to 1743.38 g, and increased chewiness from 673.03 to 939.84 g. This treatment also showed favorable emulsifying behavior. The strongest LAL inhibition occurred at 25/40 kHz, where LAL decreased from 7961.24 to 4868.88 mg/kg, corresponding to a 38.8% reduction. Structural analyses indicated that ultrasound-assisted glycation induced MP unfolding, thiol exposure, hydrophobic rearrangement, and oxidative modification to different extents. Overall, 25/28 kHz may be more suitable when balanced gel quality, emulsifying performance, and safety control are required. In contrast, 25/40 kHz may be preferred when LAL reduction is the primary objective. Full article