The oxidative environment and protein damage

The development of volatile off-flavor compounds in soy protein isolates and plant meat during storage

The off-flavor associated with soy protein isolate (SPI) has negatively impacted the full acceptance of plant meat. This study investigated the factors that contribute to the development of volatile compounds as well as the volatile compounds responsible for the off-flavors. The main objective of this study was to investigate the formation of volatile off-flavor compounds in soy protein isolates and plant meat during storage. The samples were stored at 4 ± 0.5 °C, 25 ± 2 °C, and 37 ± 1 °C for durations of 0, 2, 4, 6, and 8 weeks, respectively. They were investigated using physicochemical properties, sensory, electronic nose (E-nose), and gas chromatography-mass spectrometry (GC-MS). The volatile off-flavor compounds were identified and plant meat exhibited significantly higher levels of off-flavors than SPI. Oil bodies, excessive moisture, elevated temperature, and extended storage were recognized as the main factors contributing to the development of off-flavors. Therefore, the extended storage of SPI and plant meat resulted in a continuous reaction that eventually caused the development of volatile off-flavor compounds.

Protein fractions in cow milk inhibit decontamination by cold atmospheric plasma

There is a growing body of research on the infection of cow milk by Prototheca algae, a potential human pathogen. This study presents investigations on plasma treatment to inactivate Prototheca directly in milk. However, microbiological tests revealed a surprisingly high survival rate of Prototheca in milk compared to saline solution treated under the same conditions. This phenomenon appears to be due to presence of proteins that act as scavengers of plasma reactive species, with OH• radicals playing a major role. Studies using MALDI-TOF MS, FTIR, XPS and UV-VIS on a model solution of peptone K (simulating the molecular structure of milk protein fractions) confirmed the high reactivity of peptides with OH• radicals, leading primarily to the substitution of hydrogen atoms with hydroxyl groups and cleavage of peptide chains. The obtained results encourage a broader consideration of proteins' role in plasma treatment processes, including applications in food products and plasma medicine.

Inactivation of mitochondrial pyruvate dehydrogenase by singlet oxygen involves lipoic acid oxidation, side-chain modification and structural changes

The multi-subunit pyruvate dehydrogenase complex (PDC) plays a crucial role in glucose oxidation as it determines whether pyruvate is used for mitochondrial oxidative phosphorylation or is converted to lactate for aerobic glycolysis. PDC contains multiple lipoic acid groups, covalently attached at lysine residues to give lipoyllysine, which are responsible for acyl group transfer and critical to complex activity. We have recently reported that both free lipoic acid, and lipoyllysine in alpha-keto glutarate dehydrogenase, are highly susceptible to singlet oxygen (1O2)-induced oxidation. We therefore hypothesized that PDC activity and structure would be influenced by 1O2 (generated using Rose Bengal and light) via modification of the lipoyllysines and other residues. PDC activity was decreased by photooxidation, with this being dependent on light exposure, O2, the presence of Rose Bengal, and D2O consistent with 1O2-mediated reactions. These changes were modulated by pre-illumination addition of free lipoic acid and lipoamide. Activity loss occurred concurrently with lipoyllysine and sidechain modification (determined by mass spectrometry) and protein aggregation (detected by SDS-PAGE). Peptide mass mapping provided evidence for modification at 42 residues (Met, Trp, His and Tyr; with modification extents of 20-50 %) and each of the lipoyllysine sites (6-20 % modification). Structure modelling indicated the modifications occur across all 4 subunit types, and occur in functional domains or at multimer interfaces, consistent with damage at multiple sites contributing to the overall loss of activity. These data indicate that PDC activity and structure are susceptible to 1O2-induced damage with potential effects on cellular pathways of glucose metabolism.

Balancing the Oral Redox State: Endogenous and Exogenous Sources of Reactive Oxygen Species and the Antioxidant Role of Lamiaceae and Asteraceae

Background/Objectives: Oral health is a complex concept involving physical, psychological, emotional, and social components. A key factor in maintaining oral tissue integrity is redox balance, which is disrupted by oxidative stress (OS) through an imbalance between reactive oxygen species (ROS) and antioxidant defenses. This study examines the contribution of endogenous and exogenous sources to OS and explores the therapeutic potential of medicinal plants from the Asteraceae and Lamiaceae families in restoring redox homeostasis and improving oral health. Methods: A literature review was conducted, analyzing the role of OS in oral diseases and the antioxidant mechanisms of selected Asteraceae species. Special attention was given to their phytochemical contents-polyphenols, flavonoids, and essential oils-and their biological relevance to oral health. Results: OS plays a critical role in the onset and progression of oral conditions such as caries, periodontitis, gingivitis, aphthous ulcers, abscesses, precancerous lesions, and oral cancers. ROS and reactive nitrogen species (RNS) cause inflammation, tissue breakdown, and salivary gland dysfunction. Asteraceae plants like Matricaria chamomilla, Calendula officinalis, Cichorium intybus, Taraxacum officinale, Arctium lappa, Achillea millefolium, and Solidago virgaurea demonstrate notable antioxidant, anti-inflammatory, and antimicrobial properties that help counteract OS and support oral homeostasis. Conclusions: Asteraceae and Lamiaceae species show high therapeutic potential in addressing OS-related oral disorders. Their bioactive compounds aid in restoring redox balance and protecting oral tissues. These findings support the integration of phytotherapeutic agents into oral healthcare and call for further clinical validation of plant-based strategies for disease prevention and management.

Nuclear SUMOylation and Proteotoxic Stress Responses to Metals with Different Ligand Preferences

Proteins are vulnerable to damage by a broad range of electrophiles, and cells contain several proteotoxic stress-monitoring systems. Main transcriptional responses to protein damage are driven by cytosolic HSF1 and NRF2 using soft nucleophile Cys-SH as sensors of electrophiles. It is unclear what stress responses are activated by poorly SH-reactive hard electrophiles. We examined protein damage responses in normal human lung cells with equitoxic doses of three carcinogenic metals with different electrophilic softness: soft, cadmium(II), intermediate, cobalt(II), and hard, chromium(III) delivered into cells using chromium(VI)/chromate. Cd(II) strongly activated cytosolic NRF2 and HSF1, produced soluble and insoluble polyubiquitinated proteins in the cytosol, and moderately elevated ER and mitochondrial unfolded protein responses and nuclear polySUMOylation. Cr(III) primarily induced nuclear protein damage and polySUMOylation and was negative for the activation of all cytoplasmic stress responses. Co(II) triggered HSF1, NRF2, and other responses seen with both Cr(III) and Cd(II) except for cytosolic polyubiquitin aggregates. Physiological levels of the antioxidant ascorbate inhibited but did not eliminate NRF2 activation by Co(II) and enhanced polySUMOylation by Cr(VI/III). For all three metals, SUMOylated proteins accumulated in nuclear PML bodies, and their formation was suppressed by PML knockdown. Inhibition of SUMOylation decreased transcription and, even more severely, protein expression of NRF2 and HSF1 targets by Cd(II) and Co(II), revealing the importance of this nuclear response in the functionality of cytosolic stress-activated pathways. Our findings demonstrate that soft and hard metal electrophiles elicit distinct proteotoxic stress responses, with the notable inability of the hard electrophile Cr(III) to trigger cytosolic damage-monitoring systems.

Litopenaeus vannamei treated with l-lysine/L-arginine helped to delay the physicochemical quality deterioration and the flavor contribution attenuation in different preparation processes

Reheating is an inevitable step for frozen prepared foods before consumption. To evaluate the influence of heating on the quality of Litopenaeus vannamei, the current study used saline, l-lysine (Lys) and L-arginine (Arg) treatments on shrimp. Lys and Arg treatments were found to be beneficial in preserving shrimp's moisture content and muscle structural integrity. It significantly reduced protein and lipid oxidation, and astaxanthin degradation (P < 0.05). The LYS and ARG groups had greater umami and richness after reheating, with aldehydes and alcohols dominating the types of volatile flavor compounds. The LYS group performed better in the sensory evaluation. Pearson correlation analysis revealed a negative relationship between TVB-N, MDA, and flavor characteristics. Molecular simulations revealed that Lys and Arg solidify the myosin structure through intermolecular interactions, reducing the negative effects of reheating on shrimp and potentially serving as a standard for primary and advanced heat treatments of aquatic foods.

The Barrier Properties of Biological Membranes Dictate How Cells Experience Oxidative Stress

Molecular oxygen, superoxide, and hydrogen peroxide are related oxidants that can each impair the growth of microorganisms. Strikingly, these species exhibit large differences in their abilities to cross biological membranes. This Perspective explains the basis of those differences, and it describes natural situations in which the permeability of membranes to oxidants determines the amount of stress that a bacterium experiences.

Participation of a cysteine tetrad in the recycling mechanism of methionine sulfoxide reductase A from radiation-tolerant Deinococcus bacteria

Methionine oxidation leads to the formation of methionine sulfoxide (MetO), which is reduced back to Met by methionine sulfoxide reductases (Msrs). The catalytic mechanism used by A-type Msr (MsrA) for MetO reduction requires a catalytic cysteine (Cys), which is converted to a sulfenic acid. In general, two resolving Cys are required for the regeneration of the catalytic Cys forming two consecutive disulfide bridges, the last one being efficiently reduced by thioredoxin (Trx). Here, we performed the biochemical characterization of MsrA from Deinococcus deserti. It possesses four Cys, two present in the active site motif (18 and 21) and two distal ones (53 and 163). We produced MsrA variants mutated for these cysteines and analyzed their capacity to reduce MetO in the presence of the NADPH-Trx reductase/Trx system, their ability to form heterodimers with Trxs, and their redox status after incubation with MetO. We show that all four Cys are involved in the regeneration process of enzyme activity by Trx. After MetO reduction by Cys18, a first disulfide bridge is formed with Cys21. A second disulfide involving Cys21 with either Cys53 or Cys163 is reduced by Trx, and a third Cys53-Cys163 disulfide can be formed and also reduced by Trx. These findings highlighting for the first time the involvement of a Cys tetrad in the catalytic and regeneration mechanisms for a MsrA are placed in a structural context by performing 3D modelling and discussed in relation to the known recycling mechanisms involving a Cys triad.

Localizatome: a database for stress-dependent subcellular localization changes in proteins

Understanding protein subcellular localization and its dynamic changes is crucial for elucidating cellular function and disease mechanisms, particularly under stress conditions, where protein localization changes can modulate cellular responses. Currently available databases provide insights into protein localization under steady-state conditions; however, stress-related dynamic localization changes remain poorly understood. Here, we present the Localizatome, a comprehensive database that captures stress-induced protein localization dynamics in living cells. Using an original high-throughput microscopy system and machine learning algorithms, we analysed the localization patterns of 10 287 fluorescent protein-fused human proteins in HeLa cells before and after exposure to oxidative stress. Our analysis revealed that 1910 proteins exhibited oxidative stress-dependent localization changes, particularly forming distinct foci. Among them, there were stress granule assembly factors and autophagy-related proteins, as well as components of various signalling pathways. Subsequent characterization identified some specific amino acid motifs and intrinsically disordered regions associated with stress-induced protein redistribution. The Localizatome provides open access to these data through a web-based interface, supporting a wide range of studies on cellular stress response and disease mechanisms. Database URL https://localizatome.embrys.jp/.

Intramolecular Histidine Cross-Links Formed via Copper-Catalyzed Oxidation of Histatin Peptides

Histidine is a versatile amino acid with metal-binding, nucleophilic, and basic properties that endow many peptides and proteins with biological activity. However, histidine itself is susceptible to oxidative modifications via post-translational modifications, photo-oxidation, and metal-catalyzed oxidation. Despite multiple investigations into these different oxidation systems, the varied attributions and differential outcomes point to significant gaps in our understanding of the coordination requirements, spectral features, and reaction products that accompany the Cu-catalyzed oxidation of histidine-containing peptides. Here, we use model peptides of Histatin-5, a salivary peptide with Cu-potentiated antifungal activity that relies on its histidine residues, to characterize the complex mixture resulting from the reaction with Cu under physiologically relevant reducing and oxidizing conditions. Characterization via LC-MS, MS/MS, UV-vis, and NMR revealed that adjacent histidine residues of the bis-His site are the main target of Cu-catalyzed oxidation, with predominant modifications being 2-oxo-His and His-His cross-links that give rise to distinctive electronic absorption features between 300-400 nm. Doubly- and triply-oxygenated peptides, intramolecular His-His cross-links, and multimers in the case of a shorter model peptide were also observed. The configuration of the bis-His motif may enable Cu reactivity not available in systems where His residues are not adjacent in sequence or space. These results expand the possibilities of oxidative modifications available to other proteins and peptides containing multiple histidines.

Redox Regulation of cAMP-Dependent Protein Kinase and Its Role in Health and Disease

Protein kinase A (PKA) is a key regulator of cellular signaling that regulates key physiological processes such as metabolism, cell proliferation, and neuronal function. While its activation by the second messenger 3',5'-cyclic adenosine triphosphate (cAMP) is well characterized, recent research highlights additional regulatory mechanisms, particularly oxidative post-translational modifications, that influence PKA's structure, activity, and substrate specificity. Both the regulatory and catalytic subunits of PKA are susceptible to redox modifications, which have been shown to play important roles in the regulation of key cellular functions, including cardiac contractility, lipid metabolism, and the immune response. Likewise, redox-dependent modulation of PKA signaling has been implicated in numerous diseases, including cardiovascular disorders, diabetes, and neurodegenerative conditions, making it a potential therapeutic target. However, the mechanisms of crosstalk between redox- and PKA-dependent signaling remain poorly understood. This review examines the structural and functional regulation of PKA, with a focus on redox-dependent modifications and their impact on PKA-dependent signaling. A deeper understanding of these mechanisms may provide new strategies for targeting oxidative stress in disease and restoring balanced PKA signaling in cells.

Unexpected Conversion of Tyrosine into a Coumaric Acid Residue at the N-Terminal Side of an Orexin Peptide Fragment Induced by UV Irradiation

The presence of reactive species exceeding the physiological self-defense mechanisms in cells and tissues, known as oxidative stress, usually leads to damage of DNA and proteins. In this work, we analyzed the impact of UV irradiation and radical species from different sources to the Tyr17-Leu33 segment of orexin A peptide, which is the minimal fragment with affinity for orexin 1 receptor. As a clear oxidation process, we detected the conversion of terminal Tyrosine residue into a mixture of E/Z coumaric acid derivatives. In fact, UV irradiation and nitrosyl radicals were found to selectively induce the deamination of tyrosine into the corresponding olefin derivative, which was confirmed by HPLC-MS and NMR investigations.

LC-MS/MS based analytical strategies for the detection of lipid peroxidation products in biological matrices

Oxidative stress (OS) arises mainly from exposure to reactive oxygen species (ROS) such as superoxide anion, hydroxyl radical, and hydrogen peroxide. These molecules can cause significant damage to proteins, DNA, and lipids, leading to various diseases. Cells fight ROS with detoxifying enzymes; however, an imbalance can cause damage leading to ischemic conditions, heart disease progression, and neurological disorders such as Alzheimer's disease. Accurate assessment of OS levels is then crucial and oxidized lipidic products are considered relevant OS biomarkers. In fact, lipids are particularly prone to ROS attack, leading to lipid peroxidation, cell membrane damage, and toxic by-products affecting DNA, proteins, and low-density lipoproteins. This review reports on recent advances in LC-MS/MS approaches for OS lipidic biomarkers, focusing on overcoming analytical challenges. 3 different classes of biomarkers have been reported, malondialdehyde, isoprostanes and oxidised sterols. For each class, the main analytical challenges with a particular focus on derivatisation procedure, sensitivity, matrix effect, ionisation have been described and discussed. The recent advancements of the LC-MS-MS procedures move towards simpler approaches, reducing errors and improving the reliability of the measurement thus enabling a comprehensive and robust OS assessment.

UV-C and hydration state drive pulsed light-induced proteome damage in Bacillus pumilus spores

Introduction

Pulsed light (PL) is a non-thermal processing technology that inactivates microorganisms through high-intensity pulses of polychromatic light, including ultraviolet-C (UV-C). While the germicidal effect of PL has been widely studied, its impact on microbial proteomes remains poorly understood. Here, we investigate the proteomic response of Bacillus pumilus DSM492 (ATCC 27142) spores to PL treatment, comparing it to conventional UV-C 254 nm exposure.

Methods

B. pumilus spores were either suspended in water or sprayed onto a polystyrene surface and exposed to PL or UV-C at fluences achieving a 5-log and a > 7-log reduction in viability. Proteomic changes were analyzed using mass spectrometry to identify proteins with decreased abundance after treatment.

Results

PL treatment induced a significantly greater proteomic alteration compared to UV-C, particularly in spores suspended in water, where the number of proteins with decreased abundance was ~6-fold higher than in spores sprayed on a polystyrene surface. Proteomic analysis revealed that the effect of PL in water was primarily due to UV-C 254 nm, whereas on polystyrene, UV-C 254 nm had no significant impact. Furthermore, proteins most affected by PL were enriched in photosensitive amino acids such as tryptophan, histidine, tyrosine, cysteine, and methionine, suggesting oxidation and photoreactivity as key degradation mechanisms.

Discussion

Although the overall inactivation rate could not be directly correlated with proteome damage, we identified that core proteins involved in DNA and RNA protection and repair were specifically targeted by PL. These findings provide new insights into the molecular mechanisms underlying PL-mediated microbial inactivation and highlight the role of protein photodamage in spore susceptibility.

Gut Microbiota Serves as a Crucial Independent Biomarker in Inflammatory Bowel Disease (IBD)

Inflammatory bowel disease (IBD), encompassing Crohn's disease (CD), ulcerative colitis (UC), and IBD unclassified (IBD-U), is a complex intestinal disorder influenced by genetic, environmental, and microbial factors. Recent evidence highlights the gut microbiota as a pivotal biomarker and modulator in IBD pathogenesis. Dysbiosis, characterized by reduced microbial diversity and altered composition, is a hallmark of IBD. A consistent decrease in anti-inflammatory bacteria, such as Faecalibacterium prausnitzii, and an increase in pro-inflammatory species, including Escherichia coli, have been observed. Metabolomic studies reveal decreased short-chain fatty acids (SCFAs) and secondary bile acids, critical for gut homeostasis, alongside elevated pro-inflammatory metabolites. The gut microbiota interacts with host immune pathways, influencing morphogens, glycosylation, and podoplanin (PDPN) expression. The disruption of glycosylation impairs mucosal barriers, while aberrant PDPN activity exacerbates inflammation. Additionally, microbial alterations contribute to oxidative stress, further destabilizing intestinal barriers. These molecular and cellular disruptions underscore the role of the microbiome in IBD pathophysiology. Emerging therapeutic strategies, including probiotics, prebiotics, and dietary interventions, aim to restore microbial balance and mitigate inflammation. Advanced studies on microbiota-targeted therapies reveal their potential to reduce disease severity and improve patient outcomes. Nevertheless, further research is needed to elucidate the bidirectional interactions between the gut microbiome and host immune responses and to translate these insights into clinical applications. This review consolidates current findings on the gut microbiota's role in IBD, emphasizing its diagnostic and therapeutic implications, and advocates for the continued exploration of microbiome-based interventions to combat this debilitating disease.

Polyphenol autoxidation and prooxidative activity induce protein oxidation and protein-polyphenol adduct formation in model systems

Polyphenols are well-known for their antioxidant properties, but their prooxidative activity remain less understood. This study quantitatively examined the formation of hydrogen peroxide (H2O2) during the autooxidation of nine different polyphenols in model systems, investigating how it impacts protein oxidation and protein-polyphenol covalent adduct formation. Polyphenols (4 mM) generated H2O2 in the range of 0.2-242 μM, depending on type of polyphenol, incubation time, temperature, and pH, but no clear relationship between polyphenol structure and H2O2 production was observed. The presence of free amino acids and proteins (bovine serum albumin and β-lactoglobulin) inhibited H2O2 formation, with Cys completely scavenging H2O2. Met was highly susceptible to oxidation with a 25-75% loss, forming methionine sulfoxide through a two-electron oxidation pathway. Trp and Tyr were oxidized to produce dioxindolyl-ʟ-alanine, kynurenine, 3,4-dihydroxyphenylalanine, N'-formylkynurenine, and 5-hydroxytryptophan in the nmol/mol-mmol/mol amino acid range. Furthermore, autoxidation of polyphenols resulted in >177 distinct amino acid/protein-polyphenol adducts as identified using LC-Orbitrap-MS/MS analysis.

Toluidine blue O demethylated photoproducts as type II photosensitizers

Toluidine blue O (TBO) is a type I-type II photosensitizer that has shown good efficacy and selectivity in antimicrobial and anticancer photodynamic therapy applications. However, its complex photochemistry with multiple photoproducts hinders its application as a photosensitizer. We have previously described the mechanism for photooxidative demethylation of TBO which in acetonitrile yields two main products: demethylated-TBO (d-TBO) and double-demethylated-TBO (dd-TBO). In the current work, we describe the photophysical properties of these two photoproducts. In acetonitrile and phosphate buffer, demethylation induces an hypsochromic shift in the absorption and fluorescence emission maxima. Fluorescence quantum yields increase slightly for the demethylated photoproducts, in agreement with the lengthening of the fluorescence lifetimes. Triplet excited states lifetimes in the presence of oxygen decreased slightly upon demethylation. However, the singlet oxygen quantum yield increased significantly reaching unity for the dd-TBO photoproduct. These results are interpreted in terms of the competing pathways of TBO photochemistry. For TBO, demethylation is the main pathway for deactivation of the excited state, while for d-TBO, demethylation and singlet oxygen generation are significant. For dd-TBO, singlet oxygen generation is the main deactivation pathway. Overall, TBO demethylated photoproducts demonstrate good potential as candidates for photodynamic therapy applications.

Genesis and regulation of C-terminal cyclic imides from protein damage

C-Terminal cyclic imides are posttranslational modifications that can arise from spontaneous intramolecular cleavage of asparagine or glutamine residues resulting in a form of irreversible protein damage. These protein damage events are recognized and removed by the E3 ligase substrate adapter cereblon (CRBN), indicating that these aging-related modifications may require cellular quality control mechanisms to prevent deleterious effects. However, the factors that determine protein or peptide susceptibility to C-terminal cyclic imide formation or their effect on protein stability have not been explored in detail. Here, we characterize the primary and secondary structures of peptides and proteins that promote intrinsic formation of C-terminal cyclic imides in comparison to deamidation, a related form of protein damage. Extrinsic effects from solution properties and stressors on the cellular proteome additionally promote C-terminal cyclic imide formation on proteins like glutathione synthetase that are susceptible to aggregation if the protein damage products are not removed by CRBN. This systematic investigation provides insight into the regions of the proteome that are prone to these unexpectedly frequent modifications, the effects of this form of protein damage on protein stability, and the biological role of CRBN.

Comparative Metabolic Analysis of Different Indica Rice Varieties Associated with Seed Storability

Seed storability is a crucial agronomic trait and indispensable for the safe storage of rice seeds and grains. Nevertheless, the metabolite mechanisms governing Indica rice seed storability under natural conditions are still poorly understood.

METHODS

Therefore, the seed storage tolerance of global rice core germplasms stored for two years under natural aging conditions were identified, and two extreme groups with different seed storabilities from the Indica rice group were analyzed using the UPLC-MS/MS metabolomic strategy.

RESULTS

Our results proved that the different rice core accessions showed significant variability in storage tolerance, and the metabolite analysis of the two Indica rice pools exhibited different levels of storability. A total of 103 differentially accumulated metabolites (DAMs) between the two pools were obtained, of which 38 were up-regulated and 65 were down-regulated, respectively. Further analysis disclosed that the aging-resistant rice accessions had higher accumulation levels of flavonoids, terpenoids, phenolic acids, organic acids, lignans, and coumarins while exhibiting lower levels of lipids and alkaloids compared to the storage-sensitive rice accessions. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis indicated that several biosynthesis pathways were involved in the observed metabolite differences, including alpha-linolenic acid metabolism, butanoate metabolism, and propanoate metabolism. Notably, inhibition of the linolenic acid metabolic pathway could enhance seed storability. Additionally, increased accumulations of organic acids, such as succinic acid, D-malic acid, and methylmalonic acid, in the butanoate and propanoate metabolisms were identified as a beneficial factor for seed storage.

CONCLUSIONS

These new findings will deepen our understanding of the underlying mechanisms governing rice storability.

Anti-oxidants as therapeutic agents for oxidative stress associated pathologies: future challenges and opportunities

Free radicals have been implicated in the pathogenesis of cancer along with cardiovascular, neurodegenerative, pulmonary and inflammatory disorders. Further, the relationship between oxidative stress and disease is distinctively established. Clinical trials using anti-oxidants for the prevention of disease progression have indicated some beneficial effects. However, these trials failed to establish anti-oxidants as therapeutic agents due to lack of efficacy. This is attributed to the fact that living systems are under dynamic redox control wherein their redox behavior is compartmentalized and simple aggregation of redox couples, distributed throughout the system, is of miniscule importance while determining their overall redox state. Further, free radical metabolism is intriguingly complex as they play plural roles segregated in a spatio-temporal manner. Depending on quality, quantity and site of generation, free radicals exhibit beneficial or harmful effects. Use of nonspecific, non-targeted, general ROS scavengers lead to systemic elimination of all types of ROS and interferes in cellular signaling. Failure of anti-oxidants to act as therapeutic agents lies in this oversimplification of extremely dynamic cellular redox environment as a static and non-compartmentalized redox state. Rather than generalizing the term "oxidative stress" if we can identify the "type of oxidative stress" in different types of diseases, a targeted and more specific anti-oxidant therapy may be developed. In this review, we discuss the concept of redox dynamics, role and type of oxidative stress in disease conditions, and current status of anti-oxidants as therapeutic agents. Further, we probe the possibility of developing novel, targeted and efficacious anti-oxidants with drug-like properties.

Boronate-Based Bioactive Compounds Activated by Peroxynitrite and Hydrogen Peroxide

Boronates react directly and stoichiometrically with peroxynitrite and hydrogen peroxide. For this reason, boronates have been widely used as peroxynitrite- and hydrogen peroxide-sensitive moieties in various donors of bioactive compounds. So far, numerous boronate-based prodrugs and theranostics have been developed, characterized, and used in biological research. Here, the kinetic aspects of their activation are discussed, and the potential benefits of modifying their original structure with a boronic or boronobenzyl moiety are described.

Participation of the stress-responsive CDSP32 thioredoxin in the modulation of chloroplast ATP-synthase activity in Solanum tuberosum

Plant thioredoxins (TRXs) are involved in numerous metabolic and signalling pathways, such as light-dependent regulation of photosynthesis. The atypical TRX CDSP32, chloroplastic drought-induced stress protein of 32 kDa, includes two TRX-fold domains and participates in responses to oxidative stress as an electron donor to other thiol reductases. Here, we further characterised potato lines modified for CDSP32 expression to clarify the physiological roles of the TRX. Upon high salt treatments, modified lines displayed changes in the abundance and redox status of CDSP32 antioxidant partners, and exhibited sensitivity to combined saline-alkaline stress. In non-stressed plants overexpressing CDSP32, a lower abundance of photosystem II subunits and ATP-synthase γ subunit was noticed. The CDSP32 co-suppressed line showed altered chlorophyll a fluorescence induction and impaired regulation of the transthylakoid membrane potential during dark/light and light/dark transitions. These data, in agreement with the previously reported interaction between CDSP32 and ATP-synthase γ subunit, suggest that CDSP32 affects the redox regulation of ATP-synthase activity. Consistently, modelling of protein complex 3-D structure indicates that CDSP32 could constitute a suitable partner of ATP-synthase γ subunit. We discuss the roles of the TRX in the regulation of both photosynthetic activity and enzymatic antioxidant network in relation with environmental conditions.

Gastrointestinal fate of proteins from commercial plant-based meat analogs: Silent passage through the stomach, oxidative stress in intestine, and gut dysbiosis in Wistar rats

Plant-based meat analogs (PBMAs) are common ultra-processed foods (UPFs) included in the vegan/vegetarian diets as presumed healthy alternatives to meat and meat products. However, such health claims need to be supported by scientific evidence. To gain further insight into this topic, two commercial UPFs typically sold as meat analogs, namely, seitan (S) and tofu (T), were included in a cereal-based chow and provided to Wistar rats for 10 weeks. A group of animals had, simultaneously, an isocaloric and isoprotein experimental diet formulated with cooked beef (B). In all cases, experimental chows (∼4 kcal/g feed) had their basal protein concentration increased from 14% to 30% using proteins from S, T, or B. Upon slaughter, in vivo protein digestibility was assessed, and the entire gastrointestinal tract (digests and tissues) was analyzed for markers of oxidative stress and untargeted metabolomics. Metagenomics was also applied to assess the variation of microbiota composition as affected by dietary protein. Diets based on PBMAs showed lower protein digestibility than those containing meat and promoted an intense luminal glycoxidative stress and an inflammatory intestinal response. The fermentation of undigested oxidized proteins from T in the colon of Wistar rats likely led to formation of mutagenic metabolites such as p-cresol. The presence of these compounds in the animal models raises concerns about the potential effects of full replacement of meat by certain PBMAs in the diet. Therefore, future research might target on translational human studies to shed light on these findings.

Oxide-Perovskites for Automotive Catalysts Biotransform and Induce Multicomponent Clearance and Hazard

Oxide-perovskites designed for automotive catalysts contain multiple metal elements whose presence is crucial to achieving the targeted performance. They are highly stable in exhaust operating conditions; however, little is known about their stability under physiological conditions. As some of the metallic components are hazardous to humans and the environment, perovskite benefits in cleaner air must be balanced with risks in a Safe and Sustainable Design (SSbD) approach. New approach methodologies (NAMs), including in chemico and in silico methods, were used for testing hazards and benefits, including catalytic activity and tolerance for temporary excess of oxygen under dynamic driving conditions. The composition and surface properties of six different lanthanum-based oxide-perovskites compromised their stability under lung physiological conditions, influencing the oxidative damage of the particles and the bioacessibility of leaching metals. We found consistent biotransformation of the oxide-perovskite materials at pH 4.5. The leached lanthanum ions, but not other metals, respeciated into lanthanum phosphate nanoparticles, which increased the overall oxidative damage in additive synergy. The NAM results in the presented SSbD approach were challenged by in vivo studies in rats and mice, which confirmed multicomponent clearance from lungs into urine and supported the comparative ranking of effects against well-characterized spinel materials. Among the perovskites, the version with reduced nickel content and doped with palladium offered the best SSbD balance, despite not improving the conventional benchmark catalytic performance and related sustainability benefits. Redesign by industry may be necessary to better fulfill all SSbD dimensions.

Modelling the Repair of Carbon-Centered Protein Radicals by Phenolic Antioxidants

Oxidative stress is a biological process that has been linked to many diseases, hence understanding how to prevent and repair it is essential to medicine. The thermodynamics and kinetics of the repair reactions of radically damaged leucine (a lateral chain in a simplified protein environment) by twenty phenolic antioxidants are studied at the M06-2X(SMD)/6-31++G(d,p) level of theory in water and pentyl ethanoate. The two repair mechanisms modelled are formal-hydrogen atom transfer (f-HAT) and single electron transfer (SET). Although all f-HAT reactions are thermodynamically favourable, only one of the phenols produced rate constants in the diffusion limit, exhibiting biological relevance. SET is not suspected to be an important repair pathway for the phenols studied. We show that the Bell-Evans-Polanyi principle, which relates thermodynamics and kinetics properties for a reaction, breaks down when comparing between the solvents, protein repair sites, and the phenolic antioxidants. While thermodynamic data can be used as valuable screening tools, the kinetic calculation of rate constants in solution is crucial for enhancing the biological relevance of theoretical studies.

Photocatalytic Degradation of Bacterial Lipopolysaccharides by Peptide-Coated TiO2 Nanoparticles

In this study, we report the degradation of smooth and rough lipopolysaccharides (LPS) from Gram-negative bacteria and of lipoteichoic acid (LTA) from Gram-positive bacteria by peptide-coated TiO2 nanoparticles (TiO2 NPs). While bare TiO2 NPs displayed minor binding to both LPS and LTA, coating TiO2 NPs with the antimicrobial peptide LL-37 dramatically increased the level of binding to both LPS and LTA, decorating these uniformly. Importantly, peptide coating did not suppress reactive oxygen species generation of TiO2 NPs; hence, UV illumination triggered pronounced degradation of LPS and LTA by peptide-coated TiO2 NPs. Structural consequences of oxidative degradation were examined by neutron reflectometry for smooth LPS, showing that degradation occurred preferentially in its outer O-antigen tails. Furthermore, cryo-TEM and light scattering showed lipopolysaccharide fragments resulting from degradation to be captured by the NP/lipopolysaccharide coaggregates. The capacity of LL-37-TiO2 NPs to capture and degrade LPS and LTA was demonstrated to be of importance for their ability to suppress lipopolysaccharide-induced activation in human monocytes at simultaneously low toxicity. Together, these results suggest that peptide-coated photocatalytic NPs offer opportunities for the confinement of infection and inflammation.

The α3β4 nAChR tissue distribution identified by fluorescent α-conotoxin [D11A]LvIA

α3β4, a vital subtype of neuronal nicotinic acetylcholine receptors (nAChRs), is widely distributed in the brain, ganglia, and adrenal glands, associated with addiction and neurological diseases. However, the lack of specific imaging tools for α3β4 nAChRs has hindered the investigation of their tissue distribution and functions. [D11A]LvIA, a peptide derived from marine cone snails, demonstrates high affinity and potency for α3β4 nAChRs, making it a valuable pharmacological tool for studying this receptor subtype. In this study, three fluorescent conjugates of [D11A]LvIA were synthesized using 6-TAMRA-SE (R), Cy3-NHS-ester (Cy3), and BODIPY-FL NHS ester (BDP) dyes. The electrophysiological activities were assessed in Xenopus laevis oocytes by two-electrodes voltage clamp (TEVC). [D11A]LvIA-Cy3 and [D11A]LvIA-BDP show improved selectivity and affinity, with IC50 values of 512.70 nM and 343.50 nM, respectively, and [D11A]LvIA-Cy3 exhibits better stability in cerebrospinal fluid (CSF). Utilizing [D11A]LvIA-Cy3, we successfully visualized the distribution of α3β4 nAChRs in rat trigeminal ganglia, retina, adrenal glands, and various brain regions. This novel fluorescent peptide provides a significant pharmacological tool for the exploration and visualization in-situ distribution of α3β4 nAChRs in different tissues and also assists in clarifying the function.

Mechanisms and therapeutic targets of carbon monoxide poisoning: A focus on reactive oxygen species

Carbon monoxide (CO) poisoning presents a substantial public health challenge that necessitates the identification of its pathological mechanisms and therapeutic targets. CO toxicity arises from tissue hypoxia-ischemia secondary to carboxyhemoglobin formation, and cellular damage mediated by CO at the cellular level. The mitochondria are the major targets of neuronal damage caused by CO. Under normal physiological conditions, mitochondria produce reactive oxygen species (ROS), which are byproducts of aerobic metabolism. While low ROS levels are crucial for essential cellular functions, including signal transduction, differentiation, responses to hypoxia and immunity, transcriptional regulation, and autophagy, excess ROS become pathological and exacerbate CO poisoning. This review presents the evidence of elevated ROS being associated with the progression of CO poisoning. Antioxidant treatments targeting ROS removal have been proven effective in mitigating CO poisoning, underscoring their therapeutic potential. In this review, we highlight the latest advances in the understanding of the role and the clinical implications of ROS in CO poisoning. We focus on cellular sources of ROS, the molecular mechanisms underlying mitochondrial oxidative stress, and potential therapeutic strategies for targeting ROS in CO poisoning.

Aminoadipic acid aggravates atherosclerotic vascular inflammation through ROS/TXNIP/NLRP3 pathway, a harmful microbial metabolite reduced by paeonol

AIM

Our previous study has found a differential microbial metabolite in atherosclerosis (AS) mice, aminoadipic acid (AAA), which was considered as a potential harmful metabolite. However, whether it can promote AS vascular inflammation and its mechanisms remain unclear. Paeonol (Pae) plays an anti-AS role by regulating the metabolic profile, but whether Pae exerts its antiatherogenic effect by reducing serum AAA levels is unknown.

RESULTS

The clinical trial results showed that the AS patients' serum AAA levels were higher than those healthy people'. Besides, AAA supplementation could increase aortic plaque size, serum inflammatory cytokines levels and liver malondialdehyde, superoxide dismutase levels in AS mice. Moreover, after AAA stimulation, the ROS levels and ASC, TXNIP, NLRP3 and caspase-1 proteins levels were increased in HUVECs, which could be reversed by antioxidant NAC and NLRP3 inhibitor. Pae significantly reduced the plaque size in the aorta, improved blood lipid levels and decreased serum inflammation factor levels in AS mice. Simultaneously, Pae could reduce the serum AAA levels of AS mice through the gut microbiota transmission. Finally, Pae inhibited NLRP3 inflammasome activation in aortas of AS mice. Broad-spectrum antibiotics could weaken the inhibitory effect of Pae on NLRP3 inflammasome.

CONCLUSION

Our study clarified that AAA could promote AS vascular inflammation via activating the ROS/TXNIP/NLRP3 pathway. Pae could inhibit AS development by reducing serum AAA levels in a microbiota-dependent manner. Taken together, we proposed that AAA could be served as a potential biomarker for AS clinical diagnosis and provided a new treatment strategy for AS.

Physiological and metabolomic analyses reveal the mechanism by which exogenous spermine improves drought resistance in alfalfa leaves (Medicago sativa L.)

Introduction

Alfalfa (Medicago sativa L.) is a globally important legume crop with high nutritional and ecological value. Drought poses a serious threat to alfalfa acreage and yields. Spermine (Spm) has been shown to protect plants from drought damage. The aim of this study was to clarify the mechanism of exogenous Spm to improve drought resistance of alfalfa.

Methods

In this study, we root applied 0.1, 0.5, and 1 mM Spm to Gannong No. 3 (G3) alfalfa under drought stress, and then determined their physiological and metabolic changes.

Results

The results showed that exogenous Spm increased chlorophyll content, chlorophyll fluorescence parameters and gas exchange parameters, enhanced antioxidant enzymes activity, improved ascorbic acid-glutathione (AsA-GSH) cycle, increased osmoregulatory substances content, reduced hydrogen peroxide and superoxide anion levels, and inhibited malondialdehyde accumulation in alfalfa under drought stress, thereby increasing plant height and leaf relative water content and enhancing drought tolerance of alfalfa. The redundancy analysis of the above physiological indicators showed that the addition of the optimal Spm to improve drought tolerance of alfalfa under drought stress was mainly achieved by increasing catalase activity and improving the ASA-GSH cycle. In addition, metabolomics analysis revealed that exogenous Spm increased the content of oxobutanedioic acid, citric acid, fumaric acid and malic acid to enhance the tricarboxylic acid cycle. Meanwhile, exogenous Spm increased endogenous Spm and proline (Pro) content to resist drought stress by enhancing Spm and Pro metabolism. Moreover, exogenous Spm increased the accumulation of the signaling substance abscisic acid.

Discussion

In conclusion, exogenous Spm enhanced drought resistance of alfalfa leaves under drought stress.

Anthracycline-induced cardiotoxicity: An overview from cellular structural perspective

Anthracyclines are broad-spectrum anticancer drugs, but their clinical use is limited due to their severe cardiotoxicity. Anthracycline-induced cardiotoxicity (AIC) remains a significant cause of heart disease-related mortality in many cancer survivors. The underlying mechanisms of AIC have been explored over the past few decades. Reactive oxygen species and drug-induced inhibition of topoisomerase II beta are well-studied mechanisms, with mitochondria being a prominently investigated organelle. Emerging mechanisms such as ferroptosis, Ca2+ overload, autophagy and inflammation mediators have been implicated in recent years. In this review, our goal is to summarize and update the roles of various mechanisms in AIC, focusing on different cellular levels and further explore promising therapeutic approaches targeting these organelles or pathways.

Photosensitized Oxidation of Free and Peptide Tryptophan to N-Formylkynurenine

The oxidation of proteins and, in particular, of tryptophan (Trp) residues leads to chemical modifications that can affect the structure and function. The oxidative damage to proteins in photochemical processes is relevant in the skin and eyes and is related to a series of pathologies triggered by exposure to electromagnetic radiation. In this work, we studied the photosensitized formation of N-formylkynurenine (NFKyn) from Trp in different reaction systems. We used two substrates: free Trp and a peptide of nine amino acid residues, with Trp being the only oxidizable residue. Two different photosensitizers were employed: Rose Bengal (RB) and pterin (Ptr). The former is a typical type II photosensitizer [acts by producing singlet oxygen (1O2)]. Ptr is the parent compound of oxidized or aromatic pterins, natural photosensitizers that accumulate in human skin under certain pathological conditions and act mainly through type I mechanisms (generation of radicals). Experimental data were collected in steady photolysis, and the irradiated solutions were analyzed by chromatography (HPLC). Results indicate that the reaction of Trp with 1O2 initiates the process leading to NFKyn, but different competitive pathways take place depending on the photosensitizer and the substrate. In Ptr-photosensitization, a type I mechanism is involved in secondary reactions accelerating the formation of NFKyn when free Trp is the substrate.

Competitive oxidation of key pentose phosphate pathway enzymes modulates the fate of intermediates and NAPDH production

The oxidative phase of the pentose phosphate pathway (PPP) involving the enzymes glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconolactonase (6PGL), and 6-phosphogluconate dehydrogenase (6PGDH), is critical to NADPH generation within cells, with these enzymes catalyzing the conversion of glucose-6-phosphate (G6P) into ribulose-5-phosphate (Ribu5-P). We have previously studied peroxyl radical (ROO•) mediated oxidative inactivation of E. coli G6PDH, 6PGL, and 6PGDH. However, these data were obtained from experiments where each enzyme was independently exposed to ROO•, a condition not reflecting biological reality. In this work we investigated how NADPH production is modulated when these enzymes are jointly exposed to ROO•. Enzyme mixtures (1:1:1 ratio) were exposed to ROO• produced from thermolysis of 100 mM 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH). NADPH was quantified at 340 nm, and protein oxidation analyzed by liquid chromatography with mass spectrometric detection (LC-MS). The data obtained were rationalized using a mathematical model. The mixture of non-oxidized enzymes, G6P and NADP+ generated ∼175 μM NADPH. Computational simulations showed a constant decrease of G6P associated with NADPH formation, consistent with experimental data. When the enzyme mixture was exposed to AAPH (3 h, 37 °C), lower levels of NADPH were detected (∼100 μM) which also fitted with computational simulations. LC-MS analyses indicated modifications at Tyr, Trp, and Met residues but at lower concentrations than detected for the isolated enzymes. Quantification of NADPH generation showed that the pathway activity was not altered during the initial stages of the oxidations, consistent with a buffering role of G6PDH towards inactivation of the oxidative phase of the pathway.

Dietary supplementation with quercetin: an ideal approach for improving meat quality and oxidative stability of broiler chickens

This study aimed to improve the eating quality of yellow-feathered broiler chicks by feeding them corn-soybean meal diets supplemented with 250, 500, and 1,000 mg/kg quercetin. we examined the impact of varying doses of dietary quercetin on the sensory quality of chicken breast meat as well as on the antioxidant enzymes, antioxidant-related signaling molecules, structure and thermal stability of myofibrillar protein (MPs), and microstructure of myogenic fibers in the meat during 24 h of postslaughter aging. Additionally, we investigated the potential correlations among antioxidant capacity, MP structure, and meat quality parameters. The results indicated that dietary supplementations with 500 and 1,000 mg/kg quercetin improved the physicochemical properties and eating quality of yellow-feathered broiler chicken breast meat during 12 to 24 h postslaughter. Additionally, quercetin improved the postslaughter oxidative stress status and reduced protein and lipid oxidation levels. It also increased hydrogen bonding interactions and α-helix content during 6 to 12 h postslaughter and decreased β-sheet content during 12 to 24 h postslaughter in chicken breast MP. This resulted in improved postslaughter MP structure and thermal stability. The correlation results indicated that the enhancement of antioxidant capacity and MP structure enhanced the physicochemical and edible qualities of yellow-feathered broiler chicken breast meat. In conclusion, the current findings suggest that dietary supplementation with quercetin is an ideal approach for improving the eating quality of chicken meat, thereby broadening our understanding of theoretical and technological applications for improving the quality of chicken.

The role of redox-active small molecules and oxidative protein post-translational modifications in seed aging

Seed vigor is a crucial indicator of seed quality. Variations in seed vigor are closely associated with seed properties and storage conditions. The vigor of mature seeds progressively declines during storage, which is called seed deterioration or aging. Seed aging induces a cascade of cellular damage, including impaired subcellular structures and macromolecules, such as lipids, proteins, and DNA. Reactive oxygen species (ROS) act as signaling molecules during seed aging causing oxidative damage and triggering programmed cell death (PCD). Mitochondria are the main site of ROS production and change morphology and function before other organelles during aging. The roles of other small redox-active molecules in regulating cell and seed vigor, such as nitric oxide (NO) and hydrogen sulfide (H2S), were identified later. ROS, NO, and H2S typically regulate protein function through post-translational modifications (PTMs), including carbonylation, S-glutathionylation, S-nitrosylation, and S-sulfhydration. These signaling molecules as well as the PTMs they induce interact to regulate cell fate and seed vigor. This review was conducted to describe the physiological changes and underlying molecular mechanisms that in seed aging and provides a comprehensive view of how ROS, NO, and H2S affect cell death and seed vigor.

Elucidating the Role of O2 Uncoupling for the Adaptation of Bacterial Biodegradation Reactions Catalyzed by Rieske Oxygenases

Oxygenation of aromatic and aliphatic hydrocarbons by Rieske oxygenases is the initial step of various biodegradation pathways for environmental organic contaminants. Microorganisms carrying Rieske oxygenases are able to quickly adapt their substrate spectra to alternative carbon and energy sources that are structurally related to the original target substrate, yet the molecular events responsible for this rapid adaptation are not well understood. Here, we evaluated the hypothesis that reactive oxygen species (ROS) generated by unproductive activation of O2, the so-called O2 uncoupling, in the presence of the alternative substrate exert a selective pressure on the bacterium for increasing the oxygenation efficiency of Rieske oxygenases. To that end, we studied wild-type 2-nitrotoluene dioxygenase from Acidovorax sp. strain JS42 and five enzyme variants that have evolved from adaptive laboratory evolution experiments with 3- and 4-nitrotoluene as alternative growth substrates. The enzyme variants showed a substantially increased oxygenation efficiency toward the new target substrates concomitant with a reduction of ROS production, while mechanisms and kinetics of enzymatic O2 activation remained unchanged. Structural analyses and docking studies suggest that amino acid substitutions in enzyme variants occurred at residues lining both substrate and O2 transport tunnels, enabling tighter binding of the target substrates in the active site. Increased oxygenation efficiencies measured in vitro for the various enzyme (variant)-substrate combinations correlated linearly with in vivo changes in growth rates for evolved Acidovorax strains expressing the variants. Our data suggest that the selective pressure from oxidative stress toward more efficient oxygenation by Rieske oxygenases was most notable when O2 uncoupling exceeded 60%.

Involvement of haptoglobin in disease development

Haptoglobin (HP) is a liver glycoprotein that is actively synthesized during inflammatory and hemolytic processes. It also has pro-oxidant and proinflammatory properties, which are a function of its genotype. The genetic polymorphism of the chains leads to synthesis of three phenotypes/proteins, which are related to the number and type of chains and their molecular weight, namely HP1-1, HP1-2 and HP2-2. Patients with HP2-2 have more vascular complications, while those with HP1-1 have fewer. HP is involved in the worsening of diseases, such as HP2-2 in aggravation of vaso-occlusive crises in sickle cell disease, and worsening of the pathophysiology of other diseases. In contrast, HP1-1 confers better protection against diseases. All of this suggests that further studies should be conducted, including experimental and analytical studies focused on demonstrating the influence of different HP genotypes on individual clinical and hematological data. This would help in understanding the role played by this genetic polymorphism in the pathophysiology of diseases.

Antioxidants are ineffective at quenching reactive oxygen species inside bacteria and should not be used to diagnose oxidative stress

A wide variety of stresses have been proposed to exert killing effects upon bacteria by stimulating the intracellular formation of reactive oxygen species (ROS). A key part of the supporting evidence has often been the ability of antioxidant compounds to protect the cells. In this study, some of the most-used antioxidants-thiourea, glutathione, N-acetylcysteine, and ascorbate-have been examined. Their ability to quench superoxide and hydrogen peroxide was verified in vitro, but the rate constants were orders of magnitude too slow for them to have an impact upon superoxide and peroxide concentrations in vivo, where these species are already scavenged by highly active enzymes. Indeed, the antioxidants were unable to protect the growth and ROS-sensitive enzymes of E. coli strains experiencing authentic oxidative stress. Similar logic posits that antioxidants cannot substantially quench hydroxyl radicals inside cells, which contain abundant biomolecules that react with them at diffusion-limited rates. Indeed, antioxidants were able to protect cells from DNA damage only if they were applied at concentrations that slow metabolism and growth. This protective effect was apparent even under anoxic conditions, when ROS could not possibly be involved, and it was replicated when growth was similarly slowed by other means. Experimenters should discard the use of antioxidants as a way of detecting intracellular oxidative stress and should revisit conclusions that have been based upon such experiments. The notable exception is that these compounds can effectively degrade hydrogen peroxide from environmental sources before it enters cells.

Microbiological interpretation of weak ultrasound enhanced biological wastewater treatment - using Escherichia coli degrading glucose as model system

The Escherichia coli (E.coli) degrading glucose irradiated by ultrasound irradiation (20 W, 14 min) was investigated as the model system, the glucose degradation increased by 13 % while the E.coli proliferation decreased by 10 % after culture for 18 h. It indicated a tradeoff effect between substrate degradation and cell proliferation, which drove the enhanced contaminants removal and excess sludge reduction in a weak ultrasound enhanced biological wastewater treatment. The enzymatic activities (catalase, superoxide dismutase, adenosine triphosphatases, lactic dehydrogenase, membrane permeability, intracellular reactive oxygen species and calcium ion of E. coli increased immediately by 12 %, 63 %, 124 %, 19 %, 15 %, 4-fold and 38-fold, respectively by ultrasound irradiation power of 20 W for 14 min. Furthermore, the membrane permeability of irradiated E. coli increased by 26 % even though the ultrasound stopped for 10 h. Additionally, pathways associated with glucose degradation and cell proliferation were continuously up-regulated and down-regulated, respectively.

Modification of extracellular matrix proteins by oxidants and electrophiles

The extracellular matrix (ECM) is critical to biological architecture and determines cellular properties, function and activity. In many situations it is highly abundant, with collagens and elastin being some of the most abundant proteins in mammals. The ECM comprises of multiple different protein species and sugar polymers, with both different isoforms and post-translational modifications (PTMs) providing a large variety of microenvironments that play a key role in determining tissue structure and health. A number of the PTMs (e.g. cross-links) present in the ECM are critical to integrity and function, whereas others are deleterious to both ECM structure and associated cells. Modifications induced by reactive oxidants and electrophiles have been reported to accumulate in some ECM with increasing age. This accumulation can be exacerbated by disease, and in particular those associated with acute or chronic inflammation, obesity and diabetes. This is likely to be due to higher fluxes of modifying agents in these conditions. In this focused review, the role and effects of oxidants and other electrophiles on ECM are discussed, with a particular focus on the artery wall and atherosclerotic cardiovascular disease. Modifications generated on ECM components are reviewed, together with the effects of these species on cellular properties including adhesion, proliferation, migration, viability, metabolic activity, gene expression and phenotype. Increasing data indicates that ECM modifications are both prevalent in human and mammalian tissues and play an important role in disease development and progression.

Optimization of boronic ester-based amphiphilic copolymers for ROS-responsive drug delivery

This study introduces boronic ester-based ROS-responsive amphiphilic copolymers for antioxidant drug delivery. Tuning the hydrophobic/hydrophilic balance optimized the size, curcumin encapsulation, ROS-triggered release, cellular uptake, and intracellular ROS scavenging. The lead P1b formulation self-assembled into stable 10 nm micelles enabling rapid ROS-triggered curcumin release and preferential cellular internalization. P1b eliminated over 90% of pathogenic intracellular ROS within 10 minutes, demonstrating a rapid antioxidant therapy.

Increased Multiplexity in Optical Tissue Clearing-Based Three-Dimensional Immunofluorescence Microscopy of the Tumor Microenvironment by Light-Emitting Diode Photobleaching

Optical tissue clearing and three-dimensional (3D) immunofluorescence (IF) microscopy is transforming imaging of the complex tumor microenvironment (TME). However, current 3D IF microscopy has restricted multiplexity; only 3 or 4 cellular and noncellular TME components can be localized in cleared tumor tissue. Here we report a light-emitting diode (LED) photobleaching method and its application for 3D multiplexed optical mapping of the TME. We built a high-power LED light irradiation device and temperature-controlled chamber for completely bleaching fluorescent signals throughout optically cleared tumor tissues without compromise of tissue and protein antigen integrity. With newly developed tissue mounting and selected region-tracking methods, we established a cyclic workflow involving IF staining, tissue clearing, 3D confocal microscopy, and LED photobleaching. By registering microscope channel images generated through 3 work cycles, we produced 8-plex image data from individual 400 μm-thick tumor macrosections that visualize various vascular, immune, and cancer cells in the same TME at tissue-wide and cellular levels in 3D. Our method was also validated for quantitative 3D spatial analysis of cellular remodeling in the TME after immunotherapy. These results demonstrate that our LED photobleaching system and its workflow offer a novel approach to increase the multiplexing power of 3D IF microscopy for studying tumor heterogeneity and response to therapy.

Computational study on the endocrine-disrupting metabolic activation of Benzophenone-3 catalyzed by cytochrome P450 1A1: A QM/MM approach

Predicting the metabolic activation mechanism and potential hazardous metabolites of environmental endocrine-disruptors is a challenging and significant task in risk assessment. Here the metabolic activation mechanism of benzophenone-3 catalyzed by P450 1A1 was investigated by using Molecular Dynamics, Quantum Mechanics/Molecular Mechanics and Density Functional Theory approaches. Two elementary reactions involved in the metabolic activation of BP-3 with P450 1A1: electrophilic addition and hydrogen abstraction reactions were both discussed. Further conversion reactions of epoxidation products, ketone products and the formaldehyde formation reaction were investigated in the non-enzymatic environment based on previous experimental reports. Binding affinities analysis of benzophenone-3 and its metabolites to sex hormone binding globulin indirectly demonstrates that they all exhibit endocrine-disrupting property. Toxic analysis shows that the eco-toxicity and bioaccumulation values of the benzophenone-3 metabolites are much lower than those of benzophenone-3. However, the metabolites are found to have skin-sensitization effects. The present study provides a deep insight into the biotransformation process of benzophenone-3 catalyzed by P450 1A1 and alerts us to pay attention to the adverse effects of benzophenone-3 and its metabolites in human livers.

Towards a better understanding of light-glucose induced modifications on the structure and biological activity of formulated Nivolumab

In the last years, monoclonal antibodies (mAbs) have rapidly escalated as biopharmaceuticals into cancer treatments, mainly for their target specificity accompanied by less side effects than the traditional chemotherapy, and stimulation of reliable long-term anti-tumoral responses. They are potentially unstable macromolecules under shaking, temperature fluctuations, humidity, and indoor and outdoor light exposure, all stressors occurring throughout their production, transport, storage, handling, and administration steps. The chemical and physical modifications of mAbs can lead not only to the loss of their bioactivity, but also to the enhancement of their immunogenicity with increasing risk of severe hypersensitivity reactions in treated patients because of aggregation. The photostability of Nivolumab, the active principle of Opdivo®, has been here studied. The chemical modifications detected by LC-MS/MS after the light stressor showed Trp and Met mono and double oxidations as primary damage induced by light on this mAb. The oxidations were stronger when the mAb was diluted in sterile glucose solution where 5-HMF, a major heat glucose degradation product, acted as singlet oxygen producer under irradiation. However, no significant changes in the mAb conformation were found. On the contrary, formation of a significant extent of aggregates has been detected after shining high simulated sunlight doses. This again took place particularly when Nivolumab was diluted in sterile glucose, thus raising a direct correlation between the aggregation and the oxidative processes. Finally, the biological activity under light stress assessed by a blockade assay test demonstrated the maintenance of the PD-1 target recognition even under high light doses and in glucose solution, in line with the preservation of the secondary and tertiary structures of the mAb. Based on our results, as sterile glucose is mostly used for children's therapies, special warnings, and precautions for healthcare professionals should be included for their use to the pediatric population.

Mitigation of viruses of concern and bacteriophage surrogates via common unit processes for water reuse: A meta-analysis

Water reuse is a growing global reality. In regulating water reuse, viruses have come to the fore as key pathogens due to high shedding rates, low infectious doses, and resilience to traditional wastewater treatments. To demonstrate the high log reductions required by emerging water reuse regulations, cost and practicality necessitate surrogates for viruses for use as challenge organisms in unit process evaluation and monitoring. Bacteriophage surrogates that are mitigated to the same or lesser extent than viruses of concern are routinely used for individual unit process testing. However, the behavior of these surrogates over a multi-barrier treatment train typical of water reuse has not been well-established. Toward this aim, we performed a meta-analysis of log reductions of common bacteriophage surrogates for five treatment processes typical of water reuse treatment trains: advanced oxidation processes, chlorination, membrane filtration, ozonation, and ultraviolet (UV) disinfection. Robust linear regression was applied to identify a range of doses consistent with a given log reduction of bacteriophages and viruses of concern for each treatment process. The results were used to determine relative conservatism of surrogates. We found that no one bacteriophage was a representative or conservative surrogate for viruses of concern across all multi-barrier treatments (encompassing multiple mechanisms of virus mitigation). Rather, a suite of bacteriophage surrogates provides both a representative range of inactivation and information about the effectiveness of individual processes within a treatment train. Based on the abundance of available data and diversity of virus treatability using these five key water reuse treatment processes, bacteriophages MS2, phiX174, and Qbeta were recommended as a core suite of surrogates for virus challenge testing.

The flavodiiron protein from Syntrophomonas wolfei has five domains and acts both as an NADH:O2 or an NADH:H2 O2 oxidoreductase

Flavodiiron proteins (FDPs) are a family of enzymes with a significant role in O2 /H2 O2 and/or NO detoxification through the reduction of these species to H2 O or N2 O, respectively. All FDPs contain a minimal catalytic unit of two identical subunits, each one having a metallo-β-lactamase-like domain harboring the catalytic diiron site, and a flavodoxin-like domain. However, more complex and diverse arrangements in terms of domains are found in this family, of which the class H enzymes are among the most complex. One of such FDPs is encoded in the genome of the anaerobic bacterium Syntrophomonas wolfei subsp. wolfei str. Goettingen G311. Besides the core domains, this protein is predicted to have three additional ones after the flavodoxin core domain: two short-chain rubredoxins and a NAD(P)H:rubredoxin oxidoreductase-like domain. This enzyme, FDP_H, was produced and characterized and the presence of the predicted cofactors was investigated by a set of biochemical and spectroscopic methodologies. Syntrophomonas wolfei FDP_H exhibited a remarkable O2 reduction activity with a kcat  = 52.0 ± 1.2 s-1 and a negligible NO reduction activity (~ 100 times lower than with O2 ), with NADH as an electron donor, that is, it is an oxygen-selective FDP. In addition, this enzyme showed the highest turnover value for H2 O2 reduction (kcat  = 19.1 ± 2.2 s-1 ) ever observed among FDPs. Kinetic studies of site-directed mutants of iron-binding cysteines at the two rubredoxin domains demonstrated the essential role of these centers since their absence leads to a significant decrease or even abolishment of O2 and H2 O2 reduction activities.

Chronic exposure to 2,2'-azobis-2-amidinopropane that induces intestinal damage and oxidative stress in larvae of Drosophila melanogaster

Embryonic development is exceptionally susceptible to pathogenic, chemistry and mechanical stressors as they can disrupt homeostasis, causing damage and impacted viability. Oxidative stress has the capacity to induce alterations and reshape the environment. However, the specific impacts of these oxidative stress-induced damages in the gastrointestinal tract of Drosophila melanogaster larvae have been minimally explored. This study used 2,2-azobis (2-amidinopropane) dihydrochloride (AAPH), a free radical generator, to investigate oxidative stress effects on Drosophila embryo development. The results showed that exposing Drosophila eggs to 30 mM AAPH during 1st instar larva, 2nd instar larva and 3rd instar larva stages significantly reduced hatching rates and pupal generation. It increased the activity of antioxidant enzymes and increased oxidative damage to proteins and MDA content, indicating severe oxidative stress. Morphological changes in 3rd individuals included decreased brush borders in enterocytes and reduced lipid vacuoles in trophocytes, essential fat bodies for insect metabolism. Immunostaining revealed elevated cleaved caspase 3, an apoptosis marker. This evidence validates the impact of oxidative stress toxicity and cell apoptosis following exposure, offering insights into comprehending the chemically induced effects of oxidative stress by AAPH on animal development.

A novel diselenide attenuates the carrageenan-induced inflammation by reducing neutrophil infiltration and the resulting tissue damage in mice

Selenium-containing compounds have emerged as promising treatment for redox-based and inflammatory diseases. This study aimed to investigate the in vitro and in vivo anti-inflammatory activity of a novel diselenide named as dibenzyl[diselanediyIbis(propane-3-1diyl)] dicarbamate (DD). DD reacted with HOCl (k = 9.2 x 107 M-1s-1), like glutathione (k = 1.2 x 108 M-1s-1), yielding seleninic and selenonic acid derivatives, and it also decreased HOCl formation by activated human neutrophils (IC50=4.6 μM) and purified myeloperoxidase (MPO) (IC50=3.8 μM). However, tyrosine, MPO-I and MPO-II substrates, did not restore HOCl formation in presence of DD. DD inhibited the oxidative burst in dHL-60 cells with no toxicity up to 25 µM for 48h. Next, an intraperitoneal administration of 25, 50, and 75 mg/kg DD decreased total leukocyte, neutrophil chemotaxis, and inflammation markers (MPO activity, lipid peroxidation, albumin exudation, nitrite, TNF-α, IL-1β, CXCL1/KC, and CXCL2/MIP-2) on a murine model of carrageenan-induced peritonitis. Likewise, 50 mg/kg DD (i.p.) decreased carrageenan-induced paw edema over 5h. Histological and immunohistochemistry analyses of the paw tissue showed decreased neutrophil count, edema area, and MPO, carbonylated, and nitrated protein staining. Furthermore, DD treatment decreased the fMLP-induced chemotaxis of human neutrophils (IC50=3.7 μM) in vitro with no toxicity. Lastly, DD presented no toxicity in a single-dose model using mice (50 mg/kg, i.p.) over 15 days and in Artemia salina bioassay (50 to 2000 µM), corroborating findings from in silico toxicological study. Altogether, these results demonstrate that DD attenuates carrageenan-induced inflammation mainly by reducing neutrophil migration and the resulting damage from MPO-mediated oxidative burst.

Egg White Protein-Proanthocyanin Complexes Stabilized Emulsions: Investigation of Physical Stability, Digestion Kinetics, and Free Fatty Acid Release Dynamics

Egg white proteins pose notable limitations in emulsion applications due to their inadequate wettability and interfacial instability. Polyphenol-driven alterations in proteins serve as an effective strategy for optimizing their properties. Herein, covalent and non-covalent complexes of egg white proteins-proanthocyanins were synthesized. The analysis of structural alterations, amino acid side chains and wettability was performed. The superior wettability (80.00° ± 2.23°) and rigid structure (2.95 GPa) of covalent complexes established favorable conditions for their utilization in emulsions. Furthermore, stability evaluation, digestion kinetics, free fatty acid (FFA) release kinetics, and correlation analysis were explored to unravel the impact of covalent and non-covalent modification on emulsion stability, dynamic digestion process, and interlinkages. Emulsion stabilized by covalent complex exhibited exceptional stabilization properties, and FFA release kinetics followed both first-order and Korsmeyer-Peppas models. This study offers valuable insights into the application of complexes of proteins-polyphenols in emulsion systems and introduces an innovative approach for analyzing the dynamics of the emulsion digestion process.

Proteomic evidence of protein degradation and oxidation in brined bighead carp fillets during long-term frozen storage

Protein degradation and oxidation are two major alterations during the storage of processed bighead carp fillets. This study conducted a comparative analysis of degraded and oxidized products as well as oxidation sites in fresh, frozen and brined frozen bighead carp fillets. Frozen storage played a dominant role in protein degradation and oxidation, and brining promoted these changes. In brined frozen samples, the decreased SDS-PAGE band intensities for tropomyosin, troponin, and myosin light chain were mainly due to their degradation. Myosin heavy chain fast skeletal muscle was the most oxidized and degraded protein during storage, with modifications such as monooxidation, protein-lipid peroxidation adducts, and α-aminoadipic semialdehydes formation. Amino acids in the tail portion of myosin were prone to oxidation than the head portions. Our results provided comprehensive insights into protein degradation and oxidation in bighead carp during storage, helping to assess the specific fate of oxidative products in future dietary investigations.