Search Results (311)

Tellurite (TeO₃²⁻) is a highly soluble and toxic oxyanion that inhibits the growth of Escherichia coli at concentrations as low as ~1 µg/mL. This toxicity has been primarily attributed to the generation of reactive oxygen species (ROS) during its intracellular reduction by thiol-containing molecules and NAD(P)H-dependent enzymes. However, under anaerobic conditions, E. coli exhibits significantly increased tellurite tolerance—up to 100-fold in minimal media—suggesting the involvement of additional, ROS-independent mechanisms. In this study, we combined chemical-genomic screening, untargeted metabolomics, and targeted biochemical assays to investigate the effects of tellurite under both aerobic and anaerobic conditions. Our findings reveal that tellurite perturbs amino acid and nucleotide metabolism, leading to intracellular imbalances that impair protein synthesis. Additionally, tellurite induces notable changes in membrane lipid composition, particularly in phosphatidylethanolamine derivatives, which may influence biophysical properties of the membrane, such as fluidity or curvature. This membrane remodeling could contribute to the increased resistance observed under anaerobic conditions, although direct evidence of altered membrane fluidity remains to be established. Overall, these results demonstrate that tellurite toxicity extends beyond oxidative stress, impacting central metabolic pathways and membrane-associated functions regardless of oxygen availability. Full article

Redox signaling is central to plant adaptation, influencing metabolic regulation, stress responses, and developmental processes through thiol-based oxidative post-translational modifications (oxiPTMs) of redox-sensitive proteins. These modifications, particularly those involving cysteine (Cys) residues, act as molecular switches that alter protein function, structure, and interactions. Advances in mass spectrometry-based redox proteomics have greatly enhanced the identification and quantification of oxiPTMs, enabling a more refined understanding of redox dynamics in plant cells. In parallel, the emergence of computational modeling, artificial intelligence (AI), and machine learning (ML) has revolutionized the ability to predict redox-sensitive residues and characterize redox-dependent signaling networks. This review provides a comprehensive synthesis of methodological advancements in redox proteomics, including enrichment strategies, quantification techniques, and real-time redox sensing technologies. It also explores the integration of computational tools for predicting S-nitrosation, sulfenylation, S-glutathionylation, persulfidation, and disulfide bond formation, highlighting key models such as CysQuant, BiGRUD-SA, DLF-Sul, and Plant PTM Viewer. Furthermore, the functional significance of redox modifications is examined in plant development, seed germination, fruit ripening, and pathogen responses. By bridging experimental proteomics with AI-driven prediction platforms, this review underscores the future potential of integrated redox systems biology and emphasizes the importance of validating computational predictions, through experimental proteomics, for enhancing crop resilience, metabolic efficiency, and precision agriculture under climate variability. Full article

Background: Dithiolopyrrolones (DTPs), such as holomycin and thiolutin, exhibit potent antibacterial activities. DTPs contain a disulfide within a unique bicyclic scaffold, which may chelate metal ions and disrupt metal-dependent cellular processes once the disulfide is reductively transformed to thiols. However, the contribution of the intrinsic redox mechanism of DTPs to their antibacterial activity remains unclear. Herein we used pyrroloformamide (Pyf) A, a DTP with a unique formyl substituent, as a prototype to study the antibacterial potential and mechanism against ESKAPE pathogens, in particular carbapenem-resistant Klebsiella pneumoniae (CRKP). Methods: The antibacterial and anti-biofilm activities of Pyf A were mainly assessed against clinical CRKP isolates. Propidium iodide staining, scanning electron microscopy, glutathione (GSH) quantification, and reactive oxygen species (ROS) analysis were utilized to infer its anti-CRKP mechanism. The synergistic antibacterial effects of Pyf A and AgNO₃ were evaluated through checkerboard and time-kill assays, as well as in vivo murine wound and catheter biofilm infection models. Results: Pyf A exhibited broad-spectrum antibacterial activity against ESKAPE pathogens with minimum inhibitory concentrations ranging from 0.25 to 4 μg/mL. It also showed potent anti-biofilm effects against CRKP. Pyf A disrupted the cell membranes of CRKP and markedly depleted intracellular GSH without triggering ROS accumulation. Pyf A and AgNO₃ showed synergistic anti-CRKP activities in vitro and in vivo, by disrupting both GSH- and thioredoxin-mediated redox homeostasis. Conclusions: Pyf A acts as a GSH-depleting agent and, when combined with AgNO₃, achieves dual-targeted disruption of bacterial thiol redox systems. This dual-targeting strategy enhances antibacterial efficacy of Pyf A and represents a promising therapeutic approach to combat CRKP infections. Full article

Male infertility contributes to approximately half of all infertility cases, with most cases associated with oxidative stress. Spermatozoa depend on finely tuned redox signaling for critical processes such as capacitation, motility, and fertilization competence; however, their unique structural and metabolic features render them particularly vulnerable to oxidative damage. Reversible oxidative modifications regulate enzymatic activity, signaling cascades, and structural stability, supporting normal sperm function, whereas irreversible oxidative damage impairs motility, acrosome reaction, and DNA integrity, contributing to male infertility. The intricate balance between physiological redox signaling and pathological oxidative stress demonstrates the potential of redox modifications as biomarkers for infertility diagnosis and as targets for antioxidant-based therapeutic interventions. This review explores the role of redox-induced protein modifications in sperm function, focusing on thiol oxidation, S-nitrosylation, sulfhydration, glutathionylation, CoAlation, and protein carbonylation. By uncovering the mechanisms of these redox modifications, we provide a framework for their modulation in the development of targeted redox interventions to improve male fertility. Full article

Nitrogen and sulfur-co-doped carbon dots (N, S-CDs) were synthesized using a simple, eco-friendly hydrothermal technique with L-cysteine as the precursor. The synthesis approach produced highly water-dispersible, heteroatom-doped CDs with surface functional groups comprising amine, carboxyl, thiol, and sulfonic acid. Data analysis of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM) confirmed their amorphous nature, nanoscale dimensions (1–8 nm, average particle size of 2.6 nm), and surface chemistry. Optical examination revealed intense and pure blue fluorescence emission under UV excitation, with excitation-dependent emission behavior attributed to surface defects and heteroatom doping. The N, S-CDs were applied as fluorescent probes for detecting perfluorooctanesulfonic acid (PFOS), a notable component of the perfluoroalkyl substances (PFAS) family, demonstrating pronounced and concentration-dependent fluorescence quenching. A linear detection range of 3.33–20 µM and a limit of detection (LOD) of 2 µM were reported using the N, S-CDs probe. UV-Vis spectral shifts and dye-interaction investigations indicated that the sensing mechanism is regulated by non-covalent interactions, primarily electrostatic and hydrophobic forces. These findings confirm the potential of N, S-CDs to be used as effective optical sensors for detecting PFOS in environmental monitoring applications. Full article

Early detection of cancer can dramatically improve long-term prognosis and survivability in a variety of different cancer types. However, for many cancer types, the ability to effectively detect early-developing tumors is challenging, especially in physiological locations with limited visibility or access. Previously, we reported a sensing platform and methodology to detect biomarker peptides found in urine from ovarian cancer patients. This sensing platform relies on peptide interactions with gold nanoclusters through thiol-mediated linkages; thus, the sensitivity of the biomarker assay is directly related to appropriate redox states of the biomarkers in question. Here, we report on an expansion of the traditional thiol-reactivity assay originally developed by Ellman to include and evaluate a variety of solution modifications that may be used in conjunction with the biomarker-sensing platform. Because biomarker peptides may be isolated from a variety of biological tissues or fluids, depending on the target condition or disease, we screened numerous solution conditions that may be directly used in sample preparation and peptide extraction. The data demonstrate that the assay maintains linearity under these various conditions. The assay was then applied to a variety of models and biomarker peptides and exhibits the expected linear response. These results demonstrate the applicability of the thiol-reactivity assay to biologically derived samples, and the flexibility to ensure sample preparation and treatment will retain the appropriate sample redox conditions to ensure optimal interactions with the biosensor platform. It also facilitates the ability to perform quality control on clinically derived biological samples to ensure appropriate preparations, and concentrations are available for application to the nanopore biosensor platform. Full article

Background: The thioredoxin system (TrxS) is crucial for maintaining redox balance by regulating cellular thiol levels and is involved in various biological processes, including cancer progression. Thioredoxin reductase (TrxR), a key component of TrxS, reduces oxidized thioredoxin (Trx) using NADPH. This study investigates the inhibitory effects of 2-bromo-2-nitro-1,3-propanediol (Bronopol, BP), a preservative, on TrxR activity and its impact on cellular thiols and cell viability. Methods: Purified recombinant TrxR and noncancer and cancer cells were treated with different concentrations of BP and TrxR activity measured. BP-treated cells were examined for effects of BP on total cellular thiol level and GSH/GSSG ratio. Results: BP effectively inhibited TrxR in a dose-dependent manner, an effect that was reversible with dithiothreitol (DTT). BP treatment significantly reduced total thiol levels, decreased the GSH/GSSG ratio, and increased reactive oxygen species (ROS) in cells. Additionally, BP decreased cell viability and induced apoptosis, as indicated by morphological changes and increased c-fos mRNA expression. Conclusions: These findings highlight BP’s potential as a TrxR inhibitor and its cytotoxicity toward both noncancer and cancer cells. The observed effects—TrxR inhibition, thiol oxidation, GSH/GSSG imbalance, and ROS accumulation—may underlie BP’s cytotoxicity. Further research is needed to explore the precise molecular mechanisms by which BP exerts these effects. Full article

This study investigated specific winemaking procedures that could increase fermentation esters and volatile thiols in Chardonnay wine during fermentation. These compounds together are known to cause tropical fruit aromas. Two levels of pre-fermentative skin contact (10 °C for 18 h) (yes/no), two levels of β-lyase addition (40 μL/L) (yes/no), and three levels of fermentation gradient temperature, FG0 (constant 13 °C), FG1 (started at 20 °C and after 96 h dropped to 13 °C), and FG2 (started at 20 °C and after ~11.5 °Brix dropped to 13 °C), were evaluated using laboratory-scale ferments in a full factorial design. Esters and the volatile thiols, 3-sulfanylhexan-1-ol (3SH), 3-sulfanylhexyl acetate (3SHA), and 4-methyl-4-sulfanylpentan-2-one (4MSP), were quantified using gas and liquid chromatography methods, respectively. The combination of skin contact and FG1 or FG2 resulted in the greatest levels of esters and thiols in Chardonnay wine. The fermentation gradient was shown to be efficient in reducing volatile compounds normally lost due to evaporation during fermentation. With these different processing techniques, it will be possible for winemakers to achieve different wine qualities depending on their chosen wine style. Full article

Plant glutathione peroxidase-like (GPXL) enzymes are thiol-based peroxidases that reduce H₂O₂ or hydroperoxides to water or alcohols using electrons principally from thioredoxin. Arabidopsis thaliana possesses eight isoenzymes (AtGPXL1−8) located in different plant organelles and have various roles in redox-dependent processes. The determination of the redox potential of 6-day-old T-DNA insertional mutants (Atgpxl1–Atgpxl8) using a cytosolic redox-sensitive fluorescent probe (roGFP2) uncovered more oxidized redox status in the shoot and/or root of the untreated mutants, except for Atgpxl5. To investigate the involvement of AtGPXLs in the growth and abiotic stress responses of seedlings, the 4-day-old Atgpxls were exposed to salt and osmotic stresses for two weeks. The evaluation of the reactive oxygen species (ROS) levels of untreated 18-day-old plants using fluorescent microscopy revealed the elevated accumulation of total ROS in the shoots and, in some cases, the roots of the mutants. Regarding the growth of roots, both the length of primary roots and/or the number of lateral roots were affected by the mutation of AtGPXLs. A strong negative correlation was observed between the ROS level of wild type shoots and the development of lateral roots, but it was altered in mutants, while in the case of Atgpxl1, Atgpxl5, and Atgpxl7 seedlings, it disappeared; in other mutants (Atgpxl4, Atgpxl6, and Atgpxl8), the correlation became stronger. Our analysis underpins the discrete role of AtGPXL enzymes in controlling the growth and development of plants by fine tuning the ROS contents and redox status in an organ-specific way. Differences in root phenotype and metabolic activity between Atgpxl mutants and wild type plants highlight the essential role of AtGPXLs in ROS processing to support growth, which is particularly evident when one GPXL isoenzyme is absent or its activity is reduced, both under normal and abiotic stress conditions. Full article

Polypyrrole (PPy) is cationic in its conducting form, requiring a charge-balancing counterion, or dopant. The release of bioactive dopants, driven by the reduction of PPy films, offers a route to controlled drug delivery. Thiol-terminated long chain poly (ethylene glycol) (PEG) reacts with a dodecylbenzene sulfonate (DBSA)-doped PPy, forming a dense overlayer and partially liberating DBSA via the chemical reduction of the film. The resulting PEG brush acts as a barrier to dopant diffusion from the film, but proteins have been shown to disrupt this layer, releasing the DBSA. The mechanism by which this disruption occurs has not been thoroughly investigated. In this study, dopant release from PEG-PPy composites was examined via systematic exposure to a variety of chemical stimuli, including macromolecules such as poly (ethylene imine), polyethylene glycol, and poloxamers, as well as small-molecular-weight alcohols, carboxylic acids, and amines. Dopant release was quantified by quartz crystal microbalance. Poly (ethylene imine) efficiently released DBSA, while anionic and uncharged macromolecules did not. All classes of small molecules triggered dopant release, with longer homologues magnifying the response. The mechanisms of dopant removal are dependent on the functional groups of the stimulating agent and include ion exchange and nucleophilic reduction of the polycationic backbone. Tosylate, salicylate, and penicillin dopants showed release behaviors similar to DBSA, demonstrating the generality of the PEG barrier. Full article

Controlling the stability of colloidal nanoparticles in multicomponent systems is crucial for advancing formulations and separation processes. This study investigates the selective agglomeration approach for binary colloidal mixtures, providing both fundamental insights into stability/agglomeration mechanisms and a scalable separation strategy. First, we established a binary model system comprising gold nanoparticles (Au NPs) and ZnS quantum dots (QDs) to assess interparticle interactions. UV-visible spectroscopy revealed that impurities released from ZnS QDs, particularly thiol-based ligands and unbound Zn ions, triggered the aggregation of Au NPs depending on their surface stabilizers. Functionalization of Au NPs with bis(p-sulfonatophenyl) phenylphosphine (BSPP) significantly enhanced colloidal stability, with unpurified BSPP-functionalized Au NPs exhibiting superior resistance to agglomeration. Building on these insights, we applied selective agglomeration to separate a complex colloidal system consisting of InP/ZnS core–shell QDs and ZnS byproducts, a critical challenge in QD synthesis that is particularly relevant for post-processing of samples that originate from large-scale flow synthesis. By systematically tuning the ethanol concentration as a poor solvent, we successfully achieved composition-dependent fractionation. Optical and spectroscopic analyses confirmed that coarse fractions were enriched in InP/ZnS QDs, while fines fractions mainly contained pure ZnS QDs, with absorption peaks at 605 nm and 290 nm, respectively. Photoluminescence spectra further demonstrated a redshift in the coarse fractions, correlating with an increase in particle size. These results underscore the potential of selective agglomeration as a scalable, post-synthesis classification method, offering a framework for controlling stability and advancing post-synthesis separation strategies in colloidal multicomponent systems. Full article

The prevalence of glutathionylated (G-) precursors of polyfunctional thiols (PFTs) over their free forms has prompted investigating how to optimize the enzymatic breakdown of these precursors with yeast during lager, ale, and non-alcoholic/low-alcoholic beer (NABLAB) fermentation trials. Some Saccharomyces cerevisiae yeasts have been selected for their higher β-lyase activity on the cysteinylated (Cys-) conjugates (up to 0.54% for SafAle^TM K-97), yet some S. pastorianus strains and one maltose-negative S. cerevisiae var. chevalieri yeast have proved to release PFTs more efficiently from G-precursors (up to 0.21% for BRAS-45 and 0.19% for SafBrew^TM LA-01). The present study aimed to explore the possibility and extent of direct release in the beer of 3-sulfanylhexanol from its synthetic γ-glutamylcysteinylated (γ-GluCys-) precursor. Release efficiency was determined by GC-PFPD after the fermentation (7 days at 24 °C and 3 days at 4 °C) of a 15 °Plato (°P) wort enriched with 15 mg/L of synthesized γ-GluCys-3SHol. Up to a 0.28–0.35% release was measured with S. pastorianus strains BRAS-45 and SafLager^TM E-30, while much lower activities (≤0.16%) were observed with S. cerevisiae yeasts, including the maltose-negative chevalieri variety. This β-lyase activity on γ-GluCys-3SHol has never been described before. Under our experimental conditions, the efficiency of release from γ-GluCys-3SHol was drastically reduced in low-density worts. A strongly strain-dependent impact of temperature was also observed. Full article

Honey is abundant in bioactive compounds, which demonstrate considerable therapeutic effects, particularly on oxidative stress and inflammation. Objectives: This work sought to evaluate the antioxidant mechanisms of Manuka honey (MH) and Ohia Lehua honey (OLH), correlating them with phytochemical analyses in a rat model of experimentally induced inflammation. Methods: The identification of polyphenolic compounds in the extracts was carried out using HPLC-ESI MS. The extracts’ antioxidant activity was evaluated in vitro through DPPH, FRAP, H₂O₂, and NO scavenging assays, while in vivo assessments included measurements of total oxidative status (TOS), total antioxidant capacity (TAC), oxidative stress index (OSI), advanced oxidation protein products (AOPP), malondialdehyde (MDA), nitric oxide (NO), and total thiols (SH). Results: The phytochemical analysis found a rich content of phenolic compounds in MH and lower quantities in OLH. In terms of in vitro activity, both MH and OLH exhibited strong DPPH radical scavenging abilities, effective NO and H₂O₂ scavenging capacities, and high FRAP-reducing power. In vivo, OLH proved highly effective in enhancing antioxidant capacity and lowering oxidative stress markers, showing significant increases in TAC and substantial reductions in TOS and OSI levels. Conversely, MH displayed limited and dose-dependent antioxidant activity, a considerable increase in TAC and SH, and a moderate decrease in TOS and OSI levels. Conclusions: To our knowledge, this is the first study to assess the phenolic content of OLH and to show its capacity to scavenge free radicals and reduce oxidative stress. The effectiveness of MH primarily relies on its increased antioxidant properties and depends on concentration. These results highlight the importance of investigating natural products in developing antioxidant strategies. Full article

Background: Inflammation-induced oxidative stress is a pathophysiological mechanism of inflammatory diseases. Treatments targeting oxidative stress can reduce inflammatory tissue damage. Objectives: This study aimed to conduct phytochemical analysis and evaluate the antioxidant effects of the hydroalcoholic extract of Matricaria recutita blossoms (M. recutita) and Zingiber officinale rhizomes (Z. officinale). Materials and Methods: The phytochemical analysis was carried out by measuring the total polyphenol content, total flavonoid content, and polyphenolic compounds’ HPLC-ESI MS. The antioxidant activity was evaluated in vitro through H₂O₂ DPPH, FRAP, and NO scavenging assays. An in vivo experiment was performed on rats with turpentine oil-induced acute inflammation. Treatments were administrated orally for 10 days, with three dilutions of each extract (100%, 50%, 25%), and compared to the CONTROL, inflammation, Diclofenac, and Trolox groups. In vivo, the antioxidant activity was evaluated by measuring the total antioxidant capacity (TAC), total oxidative status (TOS), oxidative stress index (OSI), malondialdehyde (MDA), nitric oxide (NO), advanced oxidation protein products (AOPP), and total thiols (SH). Results: The phytochemical analysis found a high content of phenolic compounds in both extracts, and the in vitro antioxidant activity was significant. In vivo, M. recutita and Z. officinale extracts proved to be effective in increasing TAC and lowering oxidative stress markers, respectively, the TOS, OSI, MDA, and NO levels. The effects were dose-dependent, with the lower concentrations being more efficient antioxidants. Matricaria recutita and Z. officinale extract effects were as good as those of trolox and diclofenac. Conclusions: Treatment with M. recutita and Z. officinale alleviated inflammation-induced oxidative stress. These findings suggest that M. recutita and Z. officinale extracts could be a promising adjuvant antioxidant therapy in inflammatory diseases. Full article

Graft copolymers have gained significant importance in various fields due to their tunable functionality and well-defined architecture. However, there are still limitations due to the compatibility of monomers and functional groups depending on the polymerization mode. Click chemistry has solved this problem through its ability to easily and quantitatively link a wide range of polymers and functional groups. The combination of click chemistry, including copper-catalyzed azide-alkyne cycloaddition (CuAAC), thiol-ene, and thiol-yne reactions, with various polymerization techniques offers a promising solution for the robust and efficient preparation of graft copolymers with the desired architecture and functionality. In this review, we present successful applications of click chemistry in the production of well-defined graft copolymers with diverse functionalities such as for electronics, energy devices, biomedical applications, and nanotechnology. Full article