Search Results (69)

Reductive stress (RS) results from the overactivity of the enzymatic and non-enzymatic antioxidant systems and from excess antioxidant agents that neutralize reactive oxygen species. Hibiscus sabdariffa Linnaeus (HSL) is a natural source of antioxidant molecules that can overload the antioxidant system. Twenty-one Wistar rats were divided into three groups: group 1 (G) G1: rats that consumed a 6% HSL infusion for one month (HSL + 6%), G2: rats that consumed a 6% HSL infusion for one month and were then given natural water for another month (HSL ± 6%), and G3: rats with natural drinking water. Renal vascular resistance (RVR) was evaluated through their responses to norepinephrine (Ne), acetylcholine (Ach), super oxide (O₂⁻), hydrogen peroxide (H₂O₂)_, and peroxynitrite (ONOO⁻). The activity of antioxidant enzymes and oxidative stress markers was evaluated. RVR was increased by Ne and H₂O₂ (p = 0.03), but it was decreased by Ach, O₂⁻, and ONOO⁻ (p = 0.01). The reduced glutathione / oxidized glutathione (GSH/GSSG) ratio and nitrates/nitrites ratio, the total antioxidant capacity, the activities of superoxide dismutase, catalase, peroxidases, glutathione peroxidase, glutathione reductase, glucose-6-phosphate, and the expression of phosphorylated NrF2 were increased (p ≤ 0.04). However, the thiol groups, adenochrome, and glutathione-S-transferase were decreased (p = 0.01) in G1 vs. G2 and G3. The excessive consumption of antioxidants provided by a 6% HSL infusion results in RS contributing to a decrease in ROS. Full article

Orpiment (As₂S₃), a yellow mineral pigment widely used in historical artworks, undergoes degradation that seriously threatens the integrity of Dunhuang murals. Reactive oxygen species (ROS) exist widely in air, which may be one reason for the color change of pigments. This study aims to investigate the degradation effects and mechanisms of four ROS—hydroxyl radical (·OH), singlet oxygen (¹O₂), peroxynitrite anion (ONOO⁻), and hydrogen peroxide (H₂O₂)—on orpiment. By simulating chemical reaction systems, the interaction processes between different ROS and orpiment were qualitatively and quantitatively analyzed, and the degradation capacities of each ROS on orpiment were evaluated. The experiments show that all ROS can induce orpiment degradation, among which ·OH exhibits the strongest degradation capacity due to its high oxidation potential, while ¹O₂, ONOO⁻, and H₂O₂ have relatively minor impacts on orpiment aging. It is the first time that a study has confirmed that ROS (especially ·OH) may drive orpiment degradation in environments, contributing to the increasing number of conservation strategies for artworks. Full article

Reactive nitrogen species (RNS), particularly peroxynitrite (ONOO⁻), play a central role in post-translational modifications (PTMs) of proteins, including fibrinogen, a key component of the coagulation cascade. This review explores the structural and functional consequences of fibrinogen nitration, with a focus on its impact on clot formation, morphology, mechanical stability, and fibrinolysis. Nitration, primarily targeting tyrosine residues within functional domains of the Aα, Bβ, and γ chains, induces conformational changes, dityrosine crosslinking, and aggregation into high molecular weight species. These modifications result in altered fibrin polymerization, the formation of porous and disorganized clot networks, reduced mechanical resilience, and variable susceptibility to fibrinolysis. Moreover, nitrated fibrinogen may affect interactions with platelets and endothelial cells, although current evidence remains limited. Emerging clinical studies support its role as both a prothrombotic mediator and a potential biomarker of oxidative stress in cardiovascular and inflammatory diseases. Finally, we explore both pharmacological interventions, such as NOX inhibitors, and natural antioxidant strategies at counteracting fibrinogen nitration. Overall, fibrinogen nitration emerges as a critical molecular event linking oxidative stress to thrombotic risk. Full article

This work reviews the complex interplay between melatonin and nitric oxide (NO) in the central nervous system (CNS), with a detailed focus on its involvement in stroke pathophysiology. Melatonin, a neurohormone with potent antioxidant, anti-inflammatory, and neuroprotective properties, and NO, a gaseous signaling molecule with diverse roles, interact crucially. In the context of ischemic stroke, NO exhibits a dual role: it can be neuroprotective (primarily via endothelial nitric oxide synthase (eNOS)) or neurotoxic (especially through inducible nitric oxide synthase (iNOS) and neuronal nitric oxide synthase (nNOS), contributing to the formation of damaging peroxynitrite (ONOO⁻)). Melatonin has consistently demonstrated neuroprotective effects in animal models of stroke. Its key mechanisms related to NO include (1) differential modulation of nitric oxide synthase isoforms, suppressing detrimental iNOS expression/activity while often preserving or enhancing beneficial eNOS; (2) direct scavenging of NO and, critically, highly reactive peroxynitrite, thereby attenuating nitrosative stress; (3) reduction in neuroinflammation, partly by promoting M2 (anti-inflammatory) microglia polarization; and (4) mitochondrial protection and decreased apoptosis. These multifaceted actions of melatonin contribute to reduced infarct volume and improved functional outcomes, underscoring its considerable therapeutic potential for ischemic stroke through the favorable modulation of the melatonin–NO axis. Full article

Red lead (Pb₃O₄) has been extensively utilized as a red pigment for centuries. However, the discoloration and blackening of red lead in historical paintings have significantly compromised the aesthetic value of mural artworks. Investigating the mechanisms behind the blackening of Pb₃O₄ is of paramount importance. This study examined the effects of four kinds of reactive oxygen species (ROS) on the aging process of Pb₃O₄ in an alkaline environment. Specifically, singlet oxygen (¹O₂), superoxide radical (O₂⁻·), hydrogen peroxide (H₂O₂), or peroxynitrite (ONOO⁻) was individually reacted with Pb₃O₄. The resulting products were analyzed qualitatively and quantitatively using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy–energy-dispersive spectroscopy (SEM-EDS), Raman spectroscopy, inductively coupled plasma mass spectrometry (ICP-MS), and UV-Vis spectroscopy. The findings indicate that singlet oxygen (¹O₂) and superoxide radicals (O₂⁻·) effectively induce the aging of Pb₃O₄, whereas hydrogen peroxide (H₂O₂) and peroxynitrite (ONOO⁻) exhibit little impact on its aging. This research elucidates the aging mechanisms of Pb₃O₄ in alkaline environments and provides valuable insights for the preservation and restoration of mural paintings. Full article

Peroxynitrite (ONOO⁻) is a reactive nitrogen species (RNS) that plays pivotal roles in various physiological and pathological processes. The recent literature has seen significant progress in the development of highly sensitive and selective fluorescent probes applicable for monitoring ONOO⁻ dynamics in live cells and a variety of animal models of human diseases. However, the clinical applications of those probes remain much less explored. This review delves into the biological roles of ONOO⁻ and summarizes the design strategies, sensing mechanisms, and bioimaging applications of near-infrared (NIR), long-wavelength, two-photon, and ratiometric fluorescent probes modified with a diverse range of functional groups responsive to ONOO⁻. Furthermore, we will discuss the remaining problems that prevent the currently developed ONOO⁻ probes from translating into clinical practice. Full article

Peroxynitrite (ONOO⁻) plays an important role in many physiological and pathological processes. Excessive ONOO⁻ in cells leads to oxidative stress and inflammation. However, precise monitoring of ONOO⁻ levels in specific organelles (e.g., mitochondria) is still lacking and urgently needed. Herein, we rationally designed a mitochondria-targeted ratiometric fluorescent probe, MOBDP-I, for imaging of ONOO⁻ in the mitochondria of inflammatory cells and model mice. This probe, MOBDP-I, was synthesized by conjugating a BODIPY fluorophore to a mitochondria-targeting moiety–indole-salt group by a carbon–carbon double bond (C=C). In the presence of ONOO⁻, the C=C bond between the BODIPY backbone and the indole-salt group was oxidized and broken, leading to an 18-fold enhancement of fluorescence at 510 nm, along with a significant fluorescence decrease at 596 nm. The ratiometric response property bestowed the probe with advantages in the precise quantification of ONOO⁻ in cells, thus allowing estimation of the extent of inflammation in living cells and mouse models of rheumatoid arthritis, peritonitis, and brain inflammation. MOBDP-I could act as an effective molecular tool to study the relationship between ONOO⁻ and the occurrence and development of inflammatory diseases. Full article

Background/Objectives: Increased sodium chloride (NaCl) intake led to leukocyte activation and impaired vasodilatation via increased oxidative stress in human/animal models. Interestingly, subpressor doses of angiotensin II (AngII) restored endothelium-dependent vascular reactivity, which was impaired in a high-salt (HS) diet in animal models. Therefore, the present study aimed to assess the effects of AngII exposure following high salt (HS) loading on endothelial cells’ (ECs’) viability, activation, and reactive oxygen species (ROS) production. Methods: The fifth passage of human aortic endothelial cells (HAECs) was cultured for 24, 48, and 72 h with NaCl, namely, the control (270 mOsmol/kg), HS320 (320 mOsmol/kg), and HS350 (350 mOsmol/kg). AngII was administered at the half-time of the NaCl incubation (10⁻⁴–10⁻⁷ mol/L). Results: The cell viability was significantly reduced after 24 h in the HS350 group and in all groups after longer incubation. AngII partly preserved the viability in the HAECs with shorter exposure and lower concentrations of NaCl. Intracellular hydrogen peroxide (H₂O₂) and peroxynitrite (ONOO⁻) significantly increased in the HS320 group following AngII exposure compared to the control, while it decreased in the HS350 group compared to the HS control. A significant decrease in superoxide anion (O₂^.−) formation was observed following AngII exposure at 10⁻⁵, 10⁻⁶, and 10⁻⁷ mol/L for both HS groups. There was a significant decrease in intracellular adhesion molecule 1 (ICAM-1) and endoglin expression in both groups following treatment with 10⁻⁴ and 10⁻⁵ mol/L of AngII. Conclusions: The results demonstrated that AngII significantly reduced ROS production at HS350 concentrations and modulated the viability, proliferation, and activation states in ECs. Full article

Peroxynitrite (ONOO⁻) is a reactive oxygen species (ROS) that takes part in the oxidation-reduction homeostasis while at the same time being responsible for activating numerous pathological pathways. Accordingly, monitoring the dynamic changes in ONOO⁻ concentration has attracted a great deal of attention, undoubtedly prompting the development of appropriate fluorescent chemosensors. Herein, we developed a novel N,O-chelated diphenylboron-based fluorescent probe (DPB) for ONOO⁻ featuring high selectivity, a quick response time (2.0 min), and a low detection limit (55 nM). DPB incorporates tetra-coordinated boron in the center of the fluorogenic core and a three-coordinated boron from the pinacolphenylboronate fragment, which acts as the recognition site for ONOO⁻. As confirmed by HR-MS and ¹H NMR, the interaction of DPB with ONOO⁻ led to an oxidative cleavage of pinacolphenylboronate moiety to produce strongly emissive derivative DPB-OH. The fluorescence enhancement is likely a result of a substantial deactivation of non-radiative decay due to the replacement of the bulky pinacolphenylboronate moiety with a compact hydroxyl group. Importantly, DPB probe exhibits negligible cytotoxicity and favorable biocompatibility allowing for an efficient tracking of ONOO⁻ in living cells and zebrafish. Overall, the current study does not only represents the first N,O-chelated diphenylboron-based fluorescent probe for a specific analyte, but also serves as a guideline for designing more potent fluorescent probes based on the chemistry of boron chelates. Full article

Nitric oxide (NO) and other reactive nitrogen species (RNS) are considered to be signaling molecules in higher plants involved in the regulation of growth and development processes. However, the molecular mechanisms of their formation, removal, and participation in plant responses to adverse environmental stimuli remain largely unclear. Therefore, the aim of this study was to assess the influence of selected single stresses and combined stresses (i.e., Rhopalosiphum padi L. aphid infestation, drought, aphid infestation, and drought) and post-stress recovery on the contents of NO and peroxynitrite anion (ONOO⁻), as well as the levels of mRNA and protein nitration (i.e., the 8-nitroguanine and protein 3-nitrotyrosine amounts, respectively), in maize seedlings (Zea mays L.). Moreover, the expression patterns of the two tested genes (nos-ip, encoding nitric oxide synthase-interacting protein, and nr1, encoding nitrate reductase 1) involved in NO metabolism in maize plants were quantified. We identified significant intervarietal, time-course, and stress-dependent differences in the levels of the quantified parameters. Under the investigated stress conditions, the aphid-resistant Waza cv. seedlings were characterized by a higher and earlier NO accumulation and mRNA nitration level and an increased expression of the two target genes (nos-ip and nr1), compared to the aphid-susceptible Złota Karłowa cv. seedlings. Conversely, the Złota Karłowa plants responded with a greater elevation in the content of ONOO⁻ and protein 3-nitrotyrosine than the Waza cv. plants The multifaceted role of NO and its derivatives in maize plants challenged by single and combined stresses, as well as during post-stress recovery, is discussed. Full article

Vascular aging is associated with the development of cardiovascular complications, in which endothelial cell senescence (ES) may play a critical role. Nitric oxide (NO) prevents human ES through inhibition of oxidative stress, and inflammatory signaling by mechanisms yet to be elucidated. Endothelial cells undergo an irreversible growth arrest and alter their functional state after a finite number of divisions, a phenomenon called replicative senescence. We assessed the contribution of NO during replicative senescence of human aortic (HAEC) and coronary (CAEC) endothelial cells, in which accumulation of the senescence marker SA-β-Gal was quantified by β-galactosidase staining on cultured cells. We found a negative correlation in passaged cell cultures from P0 to P12, between a reduction in NO production with increased ES and the formation of reactive oxygen (ROS) and nitrogen (ONOO⁻) species, indicative of oxidative and nitrosative stress. The effect of ES was evidenced by reduced expression of endothelial Nitric Oxide Synthase (eNOS), Interleukin Linked Kinase (ILK), and Heat shock protein 90 (Hsp90), alongside a significant increase in the BH2/BH4 ratio, inducing the uncoupling of eNOS, favoring the production of superoxide and peroxynitrite species, and fostering an inflammatory environment, as confirmed by the levels of Cyclophilin A (CypA) and its receptor Extracellular Matrix Metalloprotease Inducer (EMMPRIN). NO prevents ES by preventing the uncoupling of eNOS, in which oxidation of BH4, which plays a key role in eNOS producing NO, may play a critical role in launching the release of free radical species, triggering an aging-related inflammatory response. Full article

Background and Objectives: Migraine is a leading cause of disability worldwide, with complex pathophysiological mechanisms involving oxidative and nitrosative stress. Recent research suggests that Indole-3-Propionic Acid (IPA) may have a neuroprotective role in reducing nitrosative stress. This study aims to elucidate the roles of IPA and nitrosative stress biomarkers in migraine patients, focusing on their potential as therapeutic targets. Materials and Methods: This cross-sectional, case-control study included 57 migraine patients and 30 healthy controls. Patients were categorized into episodic migraine (EM) and chronic migraine (CM) groups. Socio-demographic and clinical characteristics were documented through structured interviews. Validated scales such as the Visual Analog Score (VAS), Headache Impact Test 6 (HIT-6), Migraine Disability Assessment Test (MIDAS), Migraine 24 h Quality of Life Scale (24 h QoL), Mini-Mental State Examination (MMSE), and Migraine Attacks–Subjective Cognitive Impairments Scale (Mig-SCog) were administered. Venous blood samples were collected, and serum levels of IPA, Nitric Oxide (NO), Nitric Oxide Synthase (NOS), and Peroxynitrite (ONOO⁻) were measured using ELISA and spectrophotometric methods. Results: Significant differences in serum IPA and NO levels were observed between migraine patients and controls. Specifically, higher serum IPA levels were found in the EM group, while higher serum NO levels were observed in the CM group. Elevated NO levels correlated with increased migraine attack frequency. Conversely, serum IPA levels showed a negative correlation with attack frequency, suggesting a protective role. Specifically, NO levels were positively correlated with the number of painful days, NSAID usage, VAS scores, HIT-6 scores, and MIDAS scores, while negatively correlated with 24 h QoL scores. Conclusions: The study highlights the significant involvement of IPA and nitrosative stress in migraine pathophysiology. Elevated IPA levels, particularly in EM patients, suggest its potential neuroprotective role. These findings underscore the importance of targeting oxidative and nitrosative stress pathways in developing effective migraine therapies. Full article

Nitric oxide (NO) has been firmly established as a key signaling molecule in plants, playing a significant role in regulating growth, development and stress responses. Given the imperative of sustainable agriculture and the urgent need to meet the escalating global demand for food, it is imperative to safeguard crop plants from the effects of climate fluctuations. Plants respond to environmental challenges by producing redox molecules, including reactive oxygen species (ROS) and reactive nitrogen species (RNS), which regulate cellular, physiological, and molecular processes. Nitric oxide (NO) plays a crucial role in plant stress tolerance, acting as a signaling molecule or free radical. NO is involved in various developmental processes in plants through diverse mechanisms. Exogenous NO supplementation can alleviate the toxicity of abiotic stresses and enhance plant resistance. In this review we summarize the studies regarding the production of NO in peroxisomes, and how its molecule and its derived products, (ONOO⁻) and S-nitrosoglutathione (GSNO) affect ROS metabolism in peroxisomes. Peroxisomal antioxidant enzymes including catalase (CAT), are key targets of NO-mediated post-translational modification (PTM) highlighting the dynamic metabolism of ROS and RNS in peroxisomes. Full article

Background: Peroxynitrite (ONOO⁻) is an oxidant linked with several human pathologies. Apigenin, a natural flavonoid known for its health benefits, remains unexplored in relation to ONOO⁻ effects. This study investigated the potential of apigenin to structurally protect fibrinogen, an essential blood clotting factor, from ONOO⁻-induced damage. Methods: Multi-approach analyses were carried out where fibrinogen was exposed to ONOO⁻ generation while testing the efficacy of apigenin. The role of apigenin against ONOO⁻-induced modifications in fibrinogen was investigated using UV spectroscopy, tryptophan or tyrosine fluorescence, protein hydrophobicity, carbonylation, and electrophoretic analyses. Results: The findings demonstrate that apigenin significantly inhibits ONOO⁻-induced oxidative damage in fibrinogen. ONOO⁻ caused reduced UV absorption, which was reversed by apigenin treatment. Moreover, ONOO⁻ diminished tryptophan and tyrosine fluorescence, which was effectively restored by apigenin treatment. Apigenin also reduced the hydrophobicity of ONOO⁻-damaged fibrinogen. Moreover, apigenin exhibited protective effects against ONOO⁻-induced protein carbonylation. SDS-PAGE analyses revealed that ONOO⁻treatment eliminated bands corresponding to fibrinogen polypeptide chains Aα and γ, while apigenin preserved these changes. Conclusions: This study highlights, for the first time, the role of apigenin in structural protection of human fibrinogen against peroxynitrite-induced nitrosative damage. Our data indicate that apigenin offers structural protection to all three polypeptide chains (Aα, Bβ, and γ) of human fibrinogen. Specifically, apigenin prevents the dislocation or breakdown of the amino acids tryptophan, tyrosine, lysine, arginine, proline, and threonine and also prevents the exposure of hydrophobic sites in fibrinogen induced by ONOO⁻. Full article