Search Results (91)

Reperfusion after acute ischemic stroke (AIS) triggers a series of ferroptosis-related molecular events, including iron dyshomeostasis, oxidative/nitrative stress, antioxidant depletion, and membrane lipid peroxidation. Conventional ferroptosis assays mainly rely on ex vivo or endpoint measurements, limiting their ability to dynamically monitor the spatiotemporal evolution of these events during ischemia–reperfusion. Recent advances in chemical sensing and optical imaging have enabled in situ detection of key ferroptosis-related nodes, such as Fe²⁺/labile iron pool, ROS/ONOO⁻, GSH/Cys/GPX4, H₂S/Cys–Met metabolism, and lipid peroxidation. In this review, we summarize sensing targets, reaction-based probe design, near-infrared and two-photon imaging, photoacoustic imaging, and multimodal validation strategies for AIS-related ferroptosis. Representative probes for H₂O₂, ONOO⁻, H₂S, Fe²⁺, and lipid peroxidation are discussed in the context of cellular models, oxygen-glucose deprivation/reoxygenation, middle cerebral artery occlusion/reperfusion, and in vivo brain imaging. We emphasize that a single probe signal cannot independently confirm ferroptosis and should be interpreted together with GPX4/ACSL4 alterations, MDA/4-HNE levels, tissue injury, neurological outcomes, and Fer-1/Lip-1 rescue experiments. Finally, we discuss current challenges, including limited tissue penetration, blood–brain barrier delivery, quantitative stability, probe safety, and clinical translation, and highlight future directions involving ratiometric, NIR/NIR-II, two-photon, multitarget, and imaging-guided validation strategies. Full article

The exact mechanisms of skin involvement in type 1 diabetes (DM1) remain poorly understood. This study aimed to evaluate the relationship between antioxidants, oxidative stress, protein glycation, and glycoxidation, as well as matrix metalloproteinase (MMP) activity, in the skin of rats with DM1, while investigating whether insulin administration improves skin homeostasis. Male Wistar rats were assigned to three groups: control, diabetes, and diabetes treated with insulin. Significantly higher expression of GSH (gluthatione) and GSH-Px (glutathione peroxidase), elevated levels of AGE (Advanced Glycation End products), DT (dityrosine), KN (kynurenine), NFKN (N-formylkynurenine) and ONOO- (peroxynitrite), as well as increased activity of GLU (β-D-glucuronidase), NADPH oxidase (NOX) and MMP-1, -2, -3, -7, -9, -11 and -13 were observed in the skin of rats with DM1. Insulin treatment normalizes the skin’s antioxidant barrier and eliminates oxidative stress. It also reduces the intensity of protein glycation and glycoxidation, though not to the levels observed in the control group. Summarizing, in diabetic skin there is a complex interaction between the thiol antioxidant barrier, oxidative damage, protein glycation and glycoxidation as well as MMP expression. Insulin restores physiological balance in skin cells; however, glycation and ECM remodeling are still more pronounced than in healthy skin. Full article

Imidazole dipeptides (IDPs), including carnosine, anserine, and balenine, are functional food ingredients found in meats. They have been reported to exhibit high antioxidant activity. 2-Oxo-imidazole dipeptides (2-oxo-IDPs) are present in trace amounts in various tissues and show notably higher antioxidant activity compared with IDPs. Trace amounts of 2-oxo-IDPs are also present in commercial IDP reagents, suggesting that they affect the antioxidant activity of IDPs. Trace amounts of 2-oxo-IDPs were detected in IDP reagents from various manufacturers by HPLC. Some reagents with trace amounts of 2-oxo-IDPs exhibited higher antioxidant activity in a DPPH radical-scavenging assay compared with high-purity IDP reagents devoid of 2-oxo-IDPs. Therefore, it is important to use highly purified IDP reagents to measure antioxidant activity accurately. The antioxidant activity of highly purified IDPs and 2-oxocarnosine (2-oxo-Car) was evaluated through their ability to protect protein and DNA from ROS. 2-Oxo-Car markedly inhibited the protein and DNA degradation by ClO⁻ and ONOO⁻ compared with IDPs. Moreover, 2-oxo-Car was not cytotoxic, even at high concentrations, and suppressed pyocyanin-induced ROS generation in C2C12 cells compared with IDPs and glutathione. Overall, 2-oxo-IDPs are effective antioxidants and are equivalent or superior to known water-soluble antioxidants, such as glutathione and vitamin C. Full article

Peroxynitrite (ONOOH/ONOO⁻) is increasingly recognized as a key intermediate in advanced oxidation processes (AOPs), yet its role in water treatment remains insufficiently defined. This study provides mechanistic insights into peroxynitrite-mediated AOPs through competition kinetics method, demonstrating that both decomposition and pollutant degradation are strongly pH-dependent, with ONOOH dominating stability and radical pathways across pH 5.0−9.0, while its decay rate decreases from 1.2 s⁻¹ to 0.0022 s⁻¹. The interplay of HO^• and diverse reactive nitrogen species (RNS, including reactive nitrogen radicals and peroxynitrite) dictates pollutant-specific degradation efficiencies, with RNS showing a unique reliance in degrading bisphenol A—contributing up to 66.7% at pH 8.0. Buffer chemistry further modulates these pathways: bicarbonate accelerates peroxynitrite decay via CO₂ and CO₃^•−-mediated acceleration (resulting in a 361.9% increase at pH 9.0), while borate promotes reactive nitrogen radical formation but suppresses HO^• contributions. Importantly, peroxynitrite was shown to facilitate N-nitrosodimethylamine formation in the presence of dimethylamine, with yields maximized under alkaline conditions and attenuated by bicarbonate. These quantitative findings underscore the critical roles of pH and buffer chemistry in optimizing peroxynitrite-based water treatment while mitigating byproduct risks. Full article

Introduction: 5-HMF is a molecule found in carbohydrate-rich foods that is associated not only with cancer and anaphylactic reactions, but also with anti-oxidant properties. Questions arose as to whether 5-HMF exhibited a catalytic effect in relation to lipid peroxidation and lipoprotein oxidation in presence of metals and/or radicals. Methods: Peroxynitrite (ONOO⁻)-induced chemiluminescence and ONOO⁻ nitration of tyrosine residues on BSA using anti-nitro-tyrosine-antibodies were used to measure the protection of 5-HMF against peroxides or nitration compared to vitamin C (VitC). The reductive potential of 5-HMF or VitC on Cu²⁺ or Fe³ was estimated using the bicinchoninic acid (BCA) or Fenton-complex method. Human plasma was used to measure the generation of malondialdehyde (MDA), 4-hydroxynonenal (HNE), and total thiols after Fe²⁺/H₂O₂ oxidation in the presence of different concentrations of 5-HMF or VitC. Finally, Cu²⁺ oxidation of LDL after 4 h was carried out with 5-HMF or VitC, measuring the concentration of MDA in LDL with the thiobarbituric assay (TBARS). Results: VitC was 4-fold more effective than 5-HMF in scavenging ONOO⁻ to nearly 91.5% at 4 mM, with the exception of 0.16 mM, where the reduction of ONOO⁻ by VitC was 3.3-fold weaker compared to 0.16 mM 5-HMF. VitC or 5-HMF at a concentration of 6 mM inhibited the nitration of tyrosine residues on BSA to nearly 90% with a similar course. While 5-HMF reduced free Fe³⁺ in presence of phenanthroline, forming Fe²⁺ (phenantroleine)₃ [Fe²⁺(phe)₃] or complexed Cu²⁺(BCA)₄ to Cu⁺(BCA)₄ weakly, VitC was 7- to 19-fold effective in doing so over all the used concentrations (0–25 mM). A Fe²⁺—H₂O₂ solution mixed with human plasma showed a 6–10 times higher optical density (OD) of MDA or HNE in the presence of 5-HMF compared to VitC. The level of thiols was significantly decreased in the presence of higher VitC levels (1 mM: 198.4 ± 7.7 µM; 2 mM: 160.0 ± 13.4 µM) compared to equal 5-HMF amounts (2562 ± 7.8 µM or 242.4 ± 2.5 µM), whereas the usage of lower levels at 0.25 µM 5-HMF resulted in a significant decrease in thiols (272.4 ± 4.0 µM) compared to VitC (312.3 ± 19.7 µM). Both VitC and 5-HMF accelerated copper-mediated oxidation of LDL equally: while the TBARS levels from 4 h oxidized LDL reached 137.7 ± 12.3 nmol/mg, it was 1.7-fold higher using 6 mM VitC (259.9 ± 10.4 nmol/mg) or 6 mM 5-HMF (239.3 ± 10.2 nmol/mg). Conclusions: 5-HMF appeared to have more pro-oxidative potential compared to VitC by causing lipid peroxidation as well as protein oxidation. Full article

Background: Tyrosine, a non-essential amino acid involved in protein biosynthesis, can undergo oxidative modification upon exposure to reactive species like the peroxynitrite radical (ONOO⁻), resulting in the formation of 3-nitrotyrosine (3-NT). High concentrations of 3-NT have been found in the periodontal tissues of rats with periodontitis and in one study involving twelve patients with periodontitis; further, a correlation between 3-NT concentrations in periodontal tissues and clinical indices of periodontitis was found in 24 patients with periodontitis. The objectives of our study were to compare salivary 3-NT concentrations in subjects with and without periodontitis, to determine whether an association exists between salivary 3-NT concentrations and periodontitis, and to evaluate the potential of salivary 3-NT concentrations for the diagnosis of periodontitis. Material and Methods: This prospective study involved the measurement of salivary 3-NT concentrations in individuals diagnosed with periodontitis—defined by the presence of periodontal tissue loss—and in individuals without periodontitis, characterized by either periodontal health or localized gingivitis affecting fewer than 30% of sites. A total of 66 participants without periodontitis and 60 with periodontitis were included. To identify variables independently linked to periodontitis, multivariate logistic regression was applied. Additionally, a receiver operating characteristic (ROC) analysis was carried out to assess the ability of salivary 3-NT levels to discriminate between the two groups. Results: Multivariate logistic regression analysis showed that the variables independently associated with periodontitis were salivary 3-NT concentrations > 4.25 ng/mL (OR = 3.22; 95% CI = 1.180–8.789; p value = 0.02), age (years) (OR = 1.12; 95% CI = 1.064–1.168; p value < 0.001), and being a never smoker (OR = 0.36; 95% CI = 0.129–0.989; p value = 0.048). The area under the curve (AUC) of salivary 3-NT concentrations for the diagnosis of periodontitis was 62% (95% CI = 53–70%; p value = 0.02). Conclusions: Our findings showed that salivary 3-NT concentrations were higher in subjects with periodontitis than in those without, that there is an association between high salivary 3-NT concentrations and periodontitis, and that salivary 3-NT concentrations may be useful for diagnosing periodontitis. Full article

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