Peroxynitrite: biochemistry, pathophysiology and development of therapeutics

A novel dual-channel fluorescent probe for the detection of peroxynitrite anions and lipid droplets in epileptic disease

Peroxynitrite (ONOO-) and lipid droplets (LDs) are crucial substances essential for maintaining normal physiological functions in biological systems. They play pivotal roles as biomarkers in the initiation and progression of various diseases, such as epilepsy. Therefore, the simultaneous detection of ONOO- and LDs in epilepsy disorders is of great importance. Here, we discovered that the fluorescence probe composed of trifluoromesulfonate and fluorophore can not only be used as the recognition site of ONOO-, but also has the property of LDs targeting. Therefore, we reasonable designed and synthesized a dual-channel fluorescent probe CBT, capable of simultaneously monitoring ONOO- and LDs. CBT exhibited exceptional dual-response properties: firstly, upon specific reaction with ONOO-, the resulting product BHD emitted a robust red fluorescent signal in the near-infrared region (749 nm); secondly, CBT selectively targeted and labeled LDs, emitting green fluorescence at 482 nm for effective LDs tracking. The signals from these two detection channels did not overlap, which significantly enhanced the accuracy and reliability of detection. Based on these characteristics, CBT has been successfully utilized in real-time imaging of ONOO- and LDs in epilepsy models of cells induced by various drugs. Notably, in a pentylenetetrazole (PTZ)-induced chronic epileptic mice model, CBT exhibited excellent efficacy in ONOO- imaging, further confirming its considerable potential for practical applications. In summary, this study validated CBT as an efficient tool capable of simultaneous detection and differentiation of ONOO- and LDs, presenting a novel and promising strategy for the early diagnosis and treatment of diseases such as epilepsy.

Functional Nonheme Diiron(II) Complexes Catalyze the Direct Reduction of Nitrite to Nitric Oxide in Relevance to the Diiron Protein YtfE

The present work reports the functional modeling chemistry of YtfE, which features a nonheme diiron active site and mediates the direct reduction of NO2- to NO. The model complex, [Fe2(HPTP)Cl2]1+ (1), reduces NO2- to NO in a 100% yield within 12 h and generates [Fe4(HPTP)2(μ-O)3(μ-OH)]3+ (2). Similar to YtfE, the reaction involves stepwise oxidation of two Fe(II) centers and product (NO) inhibition, of which the latter produces [Fe2(HPTP)(NO)2Cl2]1+ (3). Complex 3 could also be synthesized by the reaction of [Fe2(HPTP)(NO)2(ClO4)]2+ (4) and chloride. Complex 1 catalyzes the reduction of NO2- to NO in the presence of PhS-, albeit with a low TON of 5, due to the formation of an insoluble product, [Fe2(HPTP)(μ-SPh)Cl2] (5). Another model complex [Fe2(HPTP)(OPr)]1+ (6), reduced NO2- to NO in an 80% yield after 24 h, generated [Fe2(HPTP)(OPr)(NO)2]1+ (7), and offered a TON of 19. The third model complex, [Fe2(HPTP)(ClO4)2]1+ (8), could reduce NO2- to NO in a 100% yield but only after 48 h. A comparison of these results establishes that easy oxidation of the Fe(II) centers, easy accessibility of the Fe(II) centers for the coordination of NO2-, and easy release of NO from the in situ generated dinitrosyl diiron complex increase the efficiency of the functional model complexes of YtfE.

Antioxidants: a comprehensive review

Antioxidants had a growing interest owing to their protective roles in food and pharmaceutical products against oxidative deterioration and in the body and against oxidative stress-mediated pathological processes. Screening of antioxidant properties of plants and plant derived compounds requires appropriate methods, which address the mechanism of antioxidant activity and focus on the kinetics of the reactions including the antioxidants. Many studies have been conducted with evaluating antioxidant activity of various samples of research interest using by different methods in food and human health. These methods were classified methods described and discussed in this review. Methods based on inhibited autoxidation are the most suited for termination-enhancing antioxidants and, for chain-breaking antioxidants while different specific studies are needed for preventive antioxidants. For this purpose, the most commonly methods used in vitro determination of antioxidant capacity of food and pharmaceutical constituents are examined and also a selection of chemical testing methods is critically reviewed and highlighting. In addition, their advantages, disadvantages, limitations and usefulness were discussed and investigated for pure molecules and raw plant extracts. The effect and influence of the reaction medium on performance of antioxidants is also addressed. Hence, this overview provides a basis and rationale for developing standardized antioxidant capacity methods for the food, nutraceuticals, and dietary supplement industries. Also, the most important advantages and shortcomings of each method were detected and highlighted. The underlying chemical principles of these methods have been explained and thoroughly analyzed. The chemical principles of methods of 1,1-diphenyl-2-picrylhydrazyl (DPPH•) radical scavenging, 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulphonate) radical (ABTS·+) scavenging, ferric ions (Fe3+) reducing assay, ferric reducing antioxidant power (FRAP) assay, cupric ions (Cu2+) reducing power assay (Cuprac), Folin-Ciocalteu reducing capacity (FCR assay), superoxide radical anion (O2·-), hydroxyl radical (OH·) scavenging, peroxyl radical (ROO·) removing, hydrogen peroxide (H2O2) decomposing, singlet oxygen (1O2) quenching assay, nitric oxide radical (NO·) scavenging assay and chemiluminescence assay are overviewed and critically discussed. Also, the general antioxidant aspects of the main food and pharmaceutical components were discussed through several methods currently used for detecting antioxidant properties of these components. This review consists of two main sections. The first section is devoted to the main components in food and their pharmaceutical applications. The second general section includes definitions of the main antioxidant methods commonly used for determining the antioxidant activity of components. In addition, some chemical, mechanistic, and kinetic properties, as well as technical details of the above mentioned methods, are provided. The general antioxidant aspects of main food components have been discussed through various methods currently used to detect the antioxidant properties of these components.

Phenyl Radical-Mediated Fluorogenic Cyclization for Specific Detection of Peroxynitrite

Peroxynitrite (ONOO-), a biological oxidizing and nitrating species responsible for post-translational modification of cellular proteins, has been implicated in numerous pathologies carrying an inflammatory component. Specific detection of ONOO- in biological systems remains a challenge, and boronates are regarded as the most promising class of probes for the detection and quantitation of ONOO-. Oxidation of boronate probes by ONOO- results in the formation of minor ONOO--specific products via a pathway involving a phenyl radical-type intermediate, in addition to the major phenolic product. Here, we report fluorogenic cyclization of the phenyl-type radical formed during oxidation of a boronate probe by ONOO-, with the production of a fluorescent product, and we propose a new approach for the specific detection of ONOO- based on this observation. We characterized the kinetics and stoichiometry of the reaction of benzophenone-2-boronic acid with ONOO- and identified 2-hydroxybenzophenone as the major product and fluorenone (FLN) and 2-nitrobenzophenone as the minor ONOO--specific products. Hydrogen peroxide neither alone nor in the presence of myeloperoxidase and nitrite produces FLN or 2-nitrobenzophenone. FLN can be selectively detected using fluorescence spectroscopy, providing a chemical principle for the development of next-generation probes for ONOO-, with noninvasive, fluorescence-based detection of ONOO--specific products. Fluorescence-based monitoring of FLN was successfully applied for the detection of ONOO- generated in situ from the decomposition of SIN-1, a thermal source of the superoxide radical anion and nitric oxide.

A hemicyanine-based dual-modal probe for fluorescence and mass spectrometry imaging of peroxynitrite in biosamples

Peroxynitrite (ONOO-) is a highly reactive oxidant formed by the reaction of nitric oxide with superoxide. Excessive ONOO- can be produced by the body in response to multiple diseases, resulting in cell death through oxidation and nitration processes. However, technical challenges arise in detection due to its high reactivity and very short lifespan. In this work, we rationally designed and synthesized a novel tetrazine-hemicyanine-based probe (TZN-HCY). This probe demonstrates the ability to capture ONOO- with high selectivity and sensitivity, enabling the detection and imaging of ONOO- in biological samples with both fluorescence and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS). The 3,6-disubstituted tetrazine moiety could react with ONOO-, and the hemicyanine skeleton with a permanent positive charge could enhance MALDI MS detection. The responsive performances of the TZN-HCY probe were verified on cell models and livers of hepatic ischemia-reperfusion injury (HIRI) model mice. Due to the applicability to dual-mode imaging, the formation of ONOO- and its content change in the liver of living mice were visualized by fluorescence imaging, while the fine-scale spatial distribution of ONOO- in liver tissues was revealed by MALDI MS imaging. This dual-modal probe could serve as a powerful tool for elucidating the diverse and complex roles of biogenic ONOO- in ischemia-reperfusion injury.

4-Octyl Itaconate Attenuates Cell Proliferation by Cellular Senescence via Glutathione Metabolism Disorders and Mitochondrial Dysfunction in Melanoma

Aims: Itaconate (IA) is synthesized in the citric acid cycle via cis-aconitate decarboxylase (ACOD1); however, its biological significance in cancer remains incompletely understood. In previous studies, 4-octyl itaconate (OI) was used as a membrane-permeable form of IA, but little detailed verification of the difference in biological activities between IA and OI exists. Here, we investigated the direct effects of IA and OI on melanoma. Results: The proliferation of melanoma cells treated with OI was significantly suppressed in vitro, and our transcriptomic analysis revealed drastic changes in the expression of glutathione metabolism-related genes in OI-treated cells. Indeed, OI treatment decreased intracellular glutathione levels, followed by increased production of reactive oxygen species and expression of γH2AX, a marker of DNA damage, and β-galactosidase, a marker of cellular senescence. We further showed that the mitochondrial respiratory capacity in B16 cells was significantly decreased by OI treatment. OI administration also suppressed the growth of B16 tumor transplants in vivo, and the expression of γH2AX was increased in tumor tissues of OI-treated mice. In addition, minimal effects of OI treatment were observed in melanocytes and normal tissues. We also proved that not only exogenous IA, which enters intracellularly, but also endogenous IA has little effect on melanoma proliferation activity, via an investigation using Acod1-overexpressing transfectants and Acod1-deficient mice. Conclusion: This work revealed that OI disrupts the antioxidant system via the collapse of glutathione metabolism and inhibits cancer cell proliferation. Antioxid. Redox Signal. 42, 547-565.

Zinc Oxide Nanoparticles Attenuated Neurochemical and Histopathological Alterations Associated with Aluminium Chloride Intoxication in Rats

The present investigation explored the potential neuroprotective role of zinc oxide nanoparticles (ZnONPs) on aluminum chloride (AlCl3)-mediated Alzheimer's disease (AD)-like symptoms. Rats were distributed into four treatment groups equally: control, ZnONPs (4 mg/kg b.wt.), AlCl3 (100 mg/kg b.wt.), and ZnONPs + AlCl3 groups. Rats were treated for 42 consecutive days. ZnONPs injection into AlCl3-treated rats suppressed the development of oxidative challenge in the cortical and hippocampal tissues, as demonstrated by the decreased neuronal pro-oxidants (malondialdehyde and nitric oxide), and the increased glutathione and catalase levels. Additionally, ZnONPs injection showed anti-inflammatory potency in response to AlCl3 by decreasing levels of tumor necrosis factor-α and interleukin-1β. Moreover, pretreatment with ZnONPs prevented neuronal cell loss by decreasing the level of pro-apoptotic caspase-3 and enhancing the anti-apoptotic B cell lymphoma 2. Furthermore, ZnONPs ameliorated the disturbed acetylcholinesterase activity, monoamines (norepinephrine, dopamine, and serotonin), excitatory (glutamic and aspartic acids), and inhibitory amino acids (GABA and glycine) in response to AlCl3 exposure. These findings indicate that ZnONPs may have the potential as an alternative therapy to minimize or prevent the neurological deficits in AD model by exhibiting antioxidative, anti-inflammation, anti-apoptosis, and neuromodulatory effects.

Ratiometric Fluorescent Probe for Sensitive Tracking of Peroxynitrite during Drug-Induced Hepatotoxicity

As an essential component of reactive oxygen species (ROS), peroxynitrite (ONOO-) plays an indispensable role in redox homeostasis and signal transduction, with anomalous levels implicated in various clinical conditions. Therefore, accurate and rapid detection of intracellular ONOO- levels is crucial for revealing its role in physiological and pathological processes. In this study, we developed a ratiometric fluorescent probe to detect ONOO- levels in biological systems. The probe demonstrated a fast reaction rate (within 15 min), outstanding selectivity, high sensitivity (limit of detection=13.32 nM), and stability in the presence of ONOO-. The proposed probe was successfully used for visualizing endogenous ONOO- in living cells and tracking changes in intracellular ONOO- levels during drug-induced hepatotoxicity using ratiometric fluorescence.

Principles of gut microbiota assembly

The gut microbiota plays a critical role in human health, yet its taxonomic complexity, interpersonal variability, and resistance to change in adulthood present challenges for understanding the factors driving shifts in its composition and function. Here, we propose a hierarchy of ecological factors governing gut microbiota assembly, stability, and resilience. At the apex of this hierarchy is habitat filtering by host-derived electron acceptors, which dictates the ecological guilds that dominate distinct gut regions. Host dietary behavior shapes niche availability within these ecological guilds by regulating nutrient availability. Priority effects preserve taxonomic stability whereas microbial antagonism governs competition for open ecological positions. This framework highlights how host control over microbial energy metabolism directs microbiota self-assembly and maintains gut homeostasis.

Profiling Proteins Involved in Peroxynitrite Homeostasis Using ROS/RNS Conditional Proteomics

Peroxynitrite (ONOO-), the product of the diffusion-controlled reaction of superoxide (O2•-) with nitric oxide (NO•), plays a crucial role in oxidative and nitrative stress and modulates key physiological processes such as redox signaling. While biological ONOO- is conventionally analyzed using 3-nitrotyrosine antibodies and fluorescent sensors, such probes lack specificity and sensitivity, making high-throughput and comprehensive profiling of ONOO--associated proteins challenging. In this study, we used a conditional proteomics approach to investigate ONOO- homeostasis by identifying its protein neighbors in cells. We developed Peroxynitrite-responsive protein Labeling reagents (Porp-L) and, for the first time, discovered 2,6-dichlorophenol as an ideal moiety that can be selectively and rapidly activated by ONOO- for labeling of proximal proteins. The reaction of Porp-L with ONOO- generated several short-lived reactive intermediates that can modify Tyr, His, and Lys residues on the protein surface. We have demonstrated the Porp-L-based conditional proteomics in immune-stimulated macrophages, which indeed identified proteins known to be involved in the generation and modification of ONOO- and revealed the endoplasmic reticulum (ER) as a ONOO- hot spot. Moreover, we discovered a previously unknown role for Ero1a, an ER-resident protein, in the formation of ONOO-. Overall, Porp-L represent a promising research tool for advancing our understanding of the biological roles of ONOO-.

Nitric oxide and peroxynitrite as new biomarkers for early diagnosis of autism

Autism spectrum disorder, or autism, is a neurodevelopmental disorder of the developing child's brain with a genetic causality. It can be diagnosed at about three years after birth when it begins to present itself via a range of neuropsychiatric symptoms. Nitric oxide is a crucial small molecule of life synthesized within cells of our body systems, including cells of our brain. Peroxynitrite is the product of reaction between superoxide anion and nitric oxide. It normally isomerizes into harmless nitrates or nitrites. However, when excessive superoxide anion is present, the cellular concentration of peroxynitrite can increase to a toxic level. Autism has been suggested to cause oxidative damage to brain cells. Until now, it is impossible to sample tissue from a live brain. Instead, stem cells can be derived (from an autism patient's somatic cells) which can then be differentiated and chemically directed to grow into miniature 3-dimensional tissue masses resembling specific brain regions (e.g., the cortex) called brain organoids. This review discusses utilizing nitric oxide and peroxynitrite as biomarkers and comparing their relative concentrations in stem cells and stem cell derived brain organoids of healthy and autistic individuals to develop a bioanalytical process for early diagnosis of autism.

Spatiotemporal Characteristics Determining the Multifaceted Nature of Reactive Oxygen, Nitrogen, and Sulfur Species in Relation to Proton Homeostasis

Significance: Reactive oxygen species (ROS), reactive nitrogen species (RNS), and reactive sulfur species (RSS) act as signaling molecules, regulating gene expression, enzyme activity, and physiological responses. However, excessive amounts of these molecular species can lead to deleterious effects, causing cellular damage and death. This dual nature of ROS, RNS, and RSS presents an intriguing conundrum that calls for a new paradigm. Recent Advances: Recent advancements in the study of photosynthesis have offered significant insights at the molecular level and with high temporal resolution into how the photosystem II oxygen-evolving complex manages to prevent harmful ROS production during the water-splitting process. These findings suggest that a dynamic spatiotemporal arrangement of redox reactions, coupled with strict regulation of proton transfer, is crucial for minimizing unnecessary ROS formation. Critical Issues: To better understand the multifaceted nature of these reactive molecular species in biology, it is worth considering a more holistic view that combines ecological and evolutionary perspectives on ROS, RNS, and RSS. By integrating spatiotemporal perspectives into global, cellular, and biochemical events, we discuss local pH or proton availability as a critical determinant associated with the generation and action of ROS, RNS, and RSS in biological systems. Future Directions: The concept of localized proton availability will not only help explain the multifaceted nature of these ubiquitous simple molecules in diverse systems but also provide a basis for new therapeutic strategies to manage and manipulate these reactive species in neural disorders, pathogenic diseases, and antiaging efforts.

Nitroxidative Stress, Cell-Signaling Pathways, and Manganese Porphyrins: Therapeutic Potential in Neuropathic Pain

Neuropathic pain, a debilitating condition arising from somatosensory system damage, significantly impacts quality of life, leading to anxiety, self-mutilation, and depression. Oxidative and nitrosative stress, an imbalance between reactive oxygen and nitrogen species (ROS/RNS) and antioxidant defenses, plays a crucial role in its pathophysiology. While reactive species are essential for physiological functions, excessive levels can cause cellular component damage, leading to neuronal dysfunction and pain. This review highlights the complex interactions between reactive species, antioxidant systems, cell signaling, and neuropathic pain. We discuss the physiological roles of ROS/RNS and the detrimental effects of oxidative and nitrosative stress. Furthermore, we explore the potential of manganese porphyrins, compounds with antioxidant properties, as promising therapeutic agents to mitigate oxidative stress and alleviate neuropathic pain by targeting key cellular pathways involved in pain. Further research is needed to fully understand their therapeutic potential in managing neuropathic pain in human and non-human animals.

The interactive toxic effect of homocysteine and copper on cardiac microvascular endothelial cells during ischemia-reperfusion injury

Hyperhomocysteinemia (HHcy) is associated with the development and progression of chronic cardiovascular diseases through the deleterious effects of high levels of homocysteine (Hcy) on the cardiovascular system. However, the exact mechanism of action of Hcy on the acute injury of the cardiovascular system following ischemia/reperfusion (I/R) remains unclear. The present study demonstrated that copper mobilization occurs during cardiac I/R, and the interactive toxic effect of Hcy and mobile Cu2+ during cardiac I/R induces necroptosis of cardiac microvascular endothelial cells (CMECs) and thus enhances cardiac dysfunction. In the present study, we utilized three cardiac I/R model: isolated rat heart, in vivo model as well as cell culture, and demonstrated that copper mobilization occurs during cardiac I/R, and the interactive toxic effect of Hcy and mobile Cu2+ during cardiac I/R induces necroptosis of cardiac microvascular endothelial cells (CMECs) and thus enhances cardiac dysfunction. Furthermore, we proved that the Cu2+ chelator TTM significantly mitigated the deleterious effects of Hcy and Cu2+ on CMECs and cardiac function both in vitro and in vivo. Mechanismly, the combinative effect of Hcy and Cu2+ are associated with the production of reactive oxygen species (ROS) and nitric oxide (NO) by NADPH oxidase (NOX) and endothelial nitric oxide synthase (eNOS), respectively. Subsequently, the overproduction of toxic peroxynitrite (ONOO-) induces CMECs necroptosis. The application of ROS scavengers in CMECs resulted in a notable reduction in necroptosis mediated by Hcy and Cu2+ under hypoxia/reperfusion (H/R) condition. These findings indicate that the mechanism by which Hcy and Cu2+ enhances cardiac dysfunction under I/R condition may be attributed to the stimulation of both NOX and eNOS activity, resulting in the generation of excessive ONOO- and subsequent necroptosis of CMECs.

Different Inactivation Mechanisms of Staphylococcus aureus and Escherichia coli in Water by Reactive Oxygen and Nitrogen Species Generated from an Argon Plasma Jet

The atmospheric pressure plasma jet (APPJ) is a promising technology for inactivating waterborne pathogens by generating diverse reactive species under ambient conditions. However, uncertainties regarding the bacterial inactivation mechanisms persist due to varying findings in prior research. This study aimed to clarify the inactivation mechanisms of two representative bacteria, Staphylococcus aureus (S. aureus, Gram-positive) and Escherichia coli (E. coli, Gram-negative), using an argon-based APPJ (Ar-APPJ) system in a controlled medium, primarily deionized water. We identified several reactive oxygen and nitrogen species (RONS), including hydrogen peroxide, peroxynitrous acid/peroxynitrite (ONOOH/ONOO-), hydroxyl radical (•OH), and hydroperoxyl radical/superoxide radical, and evaluated their roles in bacterial inactivation. Inactivation experiments and quantification of suspected RONS revealed that ONOOH was the primary lethal agent for S. aureus, while •OH predominantly inactivated E. coli. Assessment of cell membrane integrity and intracellular RONS levels showed that E. coli, with its thinner cell wall, was more vulnerable to surface damage caused by •OH. In contrast, for S. aureus, with its thicker cell wall, intracellular attack by penetrated ONOOH, being significantly more diffusive than •OH, was more effective, as •OH alone could not induce sufficient surface damage. These findings advance our understanding of bacterial inactivation by the Ar-APPJ and provide valuable insights for designing effective water disinfection strategies utilizing this technology.

Physicochemical properties of plasma-activated water and associated antimicrobial activity against fungi and bacteria

Plasma-activated water (PAW), generated through Surface Dielectric Barrier Discharge, was tested against microbial contaminants. We assessed how the time of exposure to plasma treatment and the gas flow rate impact the chemical composition of PAW, and, in turn, how it influences these factors influence its efficacy against microorganisms. The effectiveness of PAW treatments was evaluated against the fungal phytopathogen Botrytis cinerea and both pathogenic (Xanthomonas campestris pv. vesicatoria) and beneficial (Bacillus amyloliquefaciens) bacteria. The physicochemical properties of PAW were assessed as the concentration of reactive species, namely, NO3- and NO2- and H2O2, pH, and oxidation-reduction potential. Higher levels of reactive species and lower pH during longer treatments were associated with greater antimicrobial efficacy. A correlation study and Principal Component Analysis demonstrated that the RONS content in PAW affected antimicrobial activity, with stronger correlations between NO2-, H2O2, and fungal inhibition, as well as between NO2- and bacterial inhibition. Almost complete inhibition was reached after 1 min of treatment for bacteria (log reduction of 4.5 for B. amyloliquefaciens and 5.1 for X. campestris) and after 3 min of treatment for B. cinerea (approximately 90% inhibition of conidial germination). The obtained results contribute to defining optimized treatment conditions using PAW for antimicrobial decontamination of plant products.

Red light excitation: illuminating photocatalysis in a new spectrum

Red-light-activated photocatalysis has become a powerful approach for achieving sustainable chemical transformations, combining high efficiency with energy-saving, mild conditions. By harnessing the deeper penetration and selectivity of red and near-infrared light, this method minimizes the side reactions typical of higher-energy sources, making it particularly suited for large-scale applications. Recent advances highlight the unique advantages of both metal-based and metal-free catalysts under red-light irradiation, broadening the range of possible reactions, from selective oxidations to complex polymerizations. In biological contexts, red-light photocatalysis enables innovative applications in phototherapy and controlled drug release, exploiting its tissue penetration and low cytotoxicity. Together, these developments underscore the versatility and impact of red-light photocatalysis, positioning it as a cornerstone of green organic chemistry with significant potential in synthetic and biomedical fields.

An Expanded Narrative Review of Neurotransmitters on Alzheimer's Disease: The Role of Therapeutic Interventions on Neurotransmission

Alzheimer's disease (AD) is a progressive neurodegenerative disease. The accumulation of amyloid-β (Aβ) plaques and tau neurofibrillary tangles are the key players responsible for the pathogenesis of the disease. The accumulation of Aβ plaques and tau affect the balance in chemical neurotransmitters in the brain. Thus, the current review examined the role of neurotransmitters in the pathogenesis of Alzheimer's disease and discusses the alterations in the neurochemical activity and cross talk with their receptors and transporters. In the presence of Aβ plaques and neurofibrillary tangles, changes may occur in the expression of neuronal receptors which in turn triggers excessive release of glutamate into the synaptic cleft contributing to cell death and neuronal damage. The GABAergic system may also be affected by AD pathology in a similar way. In addition, decreased receptors in the cholinergic system and dysfunction in the dopamine neurotransmission of AD pathology may also contribute to the damage to cognitive function. Moreover, the presence of deficiencies in noradrenergic neurons within the locus coeruleus in AD suggests that noradrenergic stimulation could be useful in addressing its pathophysiology. The regulation of melatonin, known for its effectiveness in enhancing cognitive function and preventing Aβ accumulation, along with the involvement of the serotonergic system and histaminergic system in cognition and memory, becomes remarkable for promoting neurotransmission in AD. Additionally, nitric oxide and adenosine-based therapeutic approaches play a protective role in AD by preventing neuroinflammation. Overall, neurotransmitter-based therapeutic strategies emerge as pivotal for addressing neurotransmitter homeostasis and neurotransmission in the context of AD. This review discussed the potential for neurotransmitter-based drugs to be effective in slowing and correcting the neurodegenerative processes in AD by targeting the neurochemical imbalance in the brain. Therefore, neurotransmitter-based drugs could serve as a future therapeutic strategy to tackle AD.

The emerging role of nitric oxide in the synaptic dysfunction of vascular dementia

With an increase in global aging, the number of people affected by cerebrovascular diseases is also increasing, and the incidence of vascular dementia-closely related to cerebrovascular risk-is increasing at an epidemic rate. However, few therapeutic options exist that can markedly improve the cognitive impairment and prognosis of vascular dementia patients. Similarly in Alzheimer's disease and other neurological disorders, synaptic dysfunction is recognized as the main reason for cognitive decline. Nitric oxide is one of the ubiquitous gaseous cellular messengers involved in multiple physiological and pathological processes of the central nervous system. Recently, nitric oxide has been implicated in regulating synaptic plasticity and plays an important role in the pathogenesis of vascular dementia. This review introduces in detail the emerging role of nitric oxide in physiological and pathological states of vascular dementia and summarizes the diverse effects of nitric oxide on different aspects of synaptic dysfunction, neuroinflammation, oxidative stress, and blood-brain barrier dysfunction that underlie the progress of vascular dementia. Additionally, we propose that targeting the nitric oxide-sGC-cGMP pathway using certain specific approaches may provide a novel therapeutic strategy for vascular dementia.

Nitric Oxide-Releasing Nanoscale Metal-Organic Layer Overcomes Hypoxia and Reactive Oxygen Species Diffusion Barriers to Enhance Cancer Radiotherapy

Hafnium (Hf)-based nanoscale metal-organic layers (MOLs) enhance radiotherapeutic effects of tissue-penetrating X-rays via a unique radiotherapy-radiodynamic therapy (RT-RDT) process through efficient generation of hydroxy radical (RT) and singlet oxygen (RDT). However, their radiotherapeutic efficacy is limited by hypoxia in deep-seated tumors and short half-lives of reactive oxygen species (ROS). Herein the conjugation of a nitric oxide (NO) donor, S-nitroso-N-acetyl-DL-penicillamine (SNAP), to the Hf12 secondary building units (SBUs) of Hf-5,5'-di-p-benzoatoporphyrin MOL is reported to afford SNAP/MOL for enhanced cancer radiotherapy. Under X-ray irradiation, SNAP/MOL efficiently generates superoxide anion (O2 -.) and releases nitric oxide (NO) in a spatio-temporally synchronized fashion. The released NO rapidly reacts with O2 -. to form long-lived and highly cytotoxic peroxynitrite which diffuses freely to the cell nucleus and efficiently causes DNA double-strand breaks. Meanwhile, the sustained release of NO from SNAP/MOL in the tumor microenvironment relieves tumor hypoxia to reduce radioresistance of tumor cells. Consequently, SNAP/MOL plus low-dose X-ray irradiation efficiently inhibits tumor growth and reduces metastasis in colorectal and triple-negative breast cancer models.

Impact of microplastics on the human digestive system: From basic to clinical

As a new type of pollutant, the harm caused by microplastics (MPs) to organisms has been the research focus. Recently, the proportion of MPs ingested through the digestive tract has gradually increased with the popularity of fast-food products, such as takeout. The damage to the digestive system has attracted increasing attention. We reviewed the literature regarding toxicity of MPs and observed that they have different effects on multiple organs of the digestive system. The mechanism may be related to the toxic effects of MPs themselves, interactions with various substances in the biological body, and participation in various signaling pathways to induce adverse reactions as a carrier of toxins to increase the time and amount of body absorption. Based on the toxicity mechanism of MPs, we propose specific suggestions to provide a theoretical reference for the government and relevant departments.

Surface-Enhanced Raman Spectroscopy for the Detection of Reactive Oxygen Species

Reactive oxygen species (ROS) play fundamental roles in various biological and chemical processes in nature and industries, including cell signaling, disease development and aging, immune defenses, environmental remediation, pharmaceutical syntheses, metal corrosion, energy production, etc. As such, their detection is of paramount importance, but their accurate identification and quantification are technically challenging due to their transient nature with short lifetimes and low steady-state concentrations. As a highly sensitive and selective analytical technique, surface-enhanced Raman spectroscopy (SERS) is promising for detecting ROS in real-time, enabling in situ monitoring of ROS-involved electrochemical and biochemical events with exceptional resolution. This review provides a comprehensive analysis of the state-of-the-art in the SERS-based detection of ROS. Herein, the principles and ROS sensing mechanisms of SERS have been critically evaluated, highlighting their emerging applications in direct and indirect ROS monitoring in electrochemical and biological systems. The developments and reaction schemes of selective SERS probes for superoxide (•O2-), hydroxyl radicals (•OH), nitric oxide (•NO), peroxynitrite (ONOO-), and hypochlorite (OCl-) are presented. Finally, technical challenges and future research directions are discussed to guide the design of SERS for ROS analysis.

Neuroprotective effects of baicalin and baicalein on the central nervous system and the underlying mechanisms

Baicalin and baicalein are the primary flavonoids derived from the desiccated root of Scutellaria baicalensis, which is a member of the Lamiaceae family; these flavonoids have diverse pharmacological properties and show significant potential for the management of central nervous system disorders. Multiple studies have indicated that these substances effectively reduce the severity of illnesses such as depression, stroke, and degenerative disorders of the central nervous system by exerting antioxidant and anti-inflammatory effects, regulating programmed cell death, and reducing mitochondrial malfunction. Recent studies have highlighted the connection between the accumulation of iron and the ability of baicalein to protect the nervous system. Given the diverse therapeutic effects of baicalein, this review aims to thoroughly investigate the regulatory pharmacological mechanisms through which baicalein influences the development of central nervous system disorders. By elucidating these mechanisms, this review contributes to the development of therapeutic approaches that target disorders of the central nervous system.

Simultaneous Imaging of pH and Peroxynitrite in the Endoplasmic Reticulum and Mitochondria: Revealing Organelle Interactions in Alzheimer's Disease Pathogenesis

pH and peroxynitrite (ONOO-) are two critical biomarkers to unveil the corresponding status of endoplasmic reticulum (ER) stress and mitochondrial dysfunction, which are closely related to Alzheimer's disease (AD). Simultaneously monitoring pH and ONOO- fluctuations in the ER and mitochondria during AD progression is pivotal for clarifying the interplay between the disorders of the two organelles and revealing AD pathogenesis. Herein, we designed and synthesized a dual-channel fluorescent probe (DCFP) to visualize pH and ONOO- in the ER and mitochondria. DCFP possessed excellent sensitivity and selectivity to pH and ONOO- without spectral crosstalk and was utilized in monitoring the two analytes within AD model cells and larval zebrafish. Importantly, DCFP could preferentially target mitochondria in normal cells and be enriched in the ER after mitochondrial depolarization. With the aid of DCFP, the slower acidification rate of the ER than that of mitochondria induced by Aβ oligomers (AβOs) was first identified, which could be ascribed to the relief of the AβOs-triggered ER stress through the Ca2+ migration from the ER to mitochondria. Moreover, continuous exposure to AβOs led to mitochondrial Ca2+ overload, accelerating the acidification and ONOO- overproduction within mitochondria. As a result, intracellular oxidative stress levels were elevated, further exacerbating ER stress and aggravating ER acidification in turn. The advanced understanding of the potential interplay between the ER and mitochondria in this work may offer new insights and methodologies for studying AD pathogenesis. The DCFP developed in this work could also be employed to study other diseases related to ER stress and mitochondrial dysfunction.

Self-Adaptive Nanocarriers Overcome Multiple Physiological Barriers to Boosting Chemotherapy of Orthotopic Pancreatic Cancer

Chemotherapy is the primary treatment option for pancreatic cancer, although nanocarrier-based drug delivery systems often struggle with multiple physiological barriers, limiting their therapeutic efficacy. Here, we developed a pH/reactive oxygen species (ROS) dual-sensitive self-adaptive nanocarrier (DATCPT) encapsulating camptothecin (CPT), an analog of the pancreatic chemotherapeutic drug irinotecan (CPT-11), to enhance chemotherapy outcomes in orthotopic pancreatic cancer by addressing multiple physiological barriers. The nanocarrier features a peripherally positively charged arginine (Arg) residue on DATCPT and is masked with an acid-labile 2,3-dimethylmaleic anhydride (DA) to improve circulation time. In the acidic tumor microenvironment (TME), DA dissociates, exposing arginine to facilitate nanocarrier binding and internalization of DATCPT. Subsequently, peroxynitrite (ONOO-) is generated by a cascade reaction between exposed Arg and ROS, which effectively activates matrix metalloproteinases (MMPs) to degrade the dense extracellular matrix (ECM) and enhance the deep accumulation and penetration of DATCPT. Meanwhile, ONOO- inhibits tumor metastasis by influencing mitochondrial function, preventing adenosine triphosphate (ATP) production, and inhibiting ATP-dependent tumor-derived microvesicles (TMVs). This study presents a promising strategy to develop efficient nanocarriers to address multiple physiological barriers in antipancreatic cancer therapy.

The Octadecanoids: Synthesis and Bioactivity of 18-Carbon Oxygenated Fatty Acids in Mammals, Bacteria, and Fungi

The octadecanoids are a broad class of lipids consisting of the oxygenated products of 18-carbon fatty acids. Originally referring to production of the phytohormone jasmonic acid, the octadecanoid pathway has been expanded to include products of all 18-carbon fatty acids. Octadecanoids are formed biosynthetically in mammals via cyclooxygenase (COX), lipoxygenase (LOX), and cytochrome P450 (CYP) activity, as well as nonenzymatically by photo- and autoxidation mechanisms. While octadecanoids are well-known mediators in plants, their role in the regulation of mammalian biological processes has been generally neglected. However, there have been significant advancements in recognizing the importance of these compounds in mammals and their involvement in the mediation of inflammation, nociception, and cell proliferation, as well as in immuno- and tissue modulation, coagulation processes, hormone regulation, and skin barrier formation. More recently, the gut microbiome has been shown to be a significant source of octadecanoid biosynthesis, providing additional biosynthetic routes including hydratase activity (e.g., CLA-HY, FA-HY1, FA-HY2). In this review, we summarize the current field of octadecanoids, propose standardized nomenclature, provide details of octadecanoid preparation and measurement, summarize the phase-I metabolic pathway of octadecanoid formation in mammals, bacteria, and fungi, and describe their biological activity in relation to mammalian pathophysiology as well as their potential use as biomarkers of health and disease.

Secondary sphere interactions modulate peroxynitrite scavenging by the E2 domain of amyloid precursor protein

Peroxynitrite (ONOO-) is a highly reactive nitrogen species that can cause significant damage to proteins, lipids, and DNA. Various enzymes, including metalloenzymes, play crucial roles in reducing ONOO- concentrations to protect cellular components. While the interaction of ONOO- with heme proteins is well known, the reduction by Cu-containing proteins is less studied. Amyloid precursor protein (APP), implicated in Alzheimer's disease, has an E2 domain that binds copper ions with a dissociation constant of KD ∼ 10-12 M and is proposed to be involved in iron homeostasis, copper trafficking, and oxidative stress response. Our recent studies using EXAFS, UV-Vis, and EPR spectroscopy revealed a previously unidentified labile water ligand in the Cu(II) site of the E2 domain, suggesting reactivity with anionic substrates like ONOO-. Experimental data showed that Cu(I)-E2 reduces ONOO- at a significant rate (1.1 × 105 M-1 s-1), comparable to native peroxynitrite scavengers, while maintaining active site integrity through multiple redox cycles. This study further investigates the mechanism of ONOO- reduction by Cu(I)-E2 using the Griess assay, demonstrating that reduction occurs via single electron transfer, forming nitrite and nitrate. This process aligns with previous findings that Cu(I)-E2 is oxidized to Cu(II)-E2 upon ONOO- reduction. Mutations at Lys435, affecting secondary sphere interactions, revealed that factors beyond electrostatics are involved in substrate recruitment. MD simulations suggest that steric hindrance from a newly formed hydrogen bond also plays a role. Understanding ONOO- reduction by the E2 domain of APP expands our knowledge of copper proteins in mitigating oxidative stress and elucidates their physiological and pathological roles, particularly in Alzheimer's disease.

A bifunctional naphthalimide-based fluorescent probe for imaging lysosomal peroxynitrite and viscosity in living cells and zebrafish

Peroxynitrite (ONOO-) and viscosity are critical indicators of lysosome functionality, intimately linked to numerous diseases' pathophysiological processes. Hence, creating reliable analytical techniques to observe fluctuations in lysosomal ONOO- and viscosity is highly important. This study presents the development of a novel naphthalimide-based fluorescent probe, Nap-Cy, specifically designed to target lysosomes and simultaneously detect both ONOO- and viscosity. Nap-Cy displayed a near-infrared fluorescence "turn-on" response to viscosity (ranging from 1.0 to 1410 cp) with an approximately 400-fold increase in intensity. At the same time, it functioned as a ratiometric probe with high sensitivity for detecting ONOO-, featuring a quick response time of approximately 10 min, a low detection limit of 42 nM, a broad pH range (5-11), and excellent selectivity for ONOO- over other chemical and biological species. Additionally, Nap-Cy was successfully applied for fluorescence imaging to monitor ONOO- and viscosity variations in SH-SY5Y cells and zebrafish across multiple channels. This research introduces a valuable molecular probe for investigating the biological functions and interactions of ONOO- and viscosity within lysosomes.

Reactive Oxygen Species, a Potential Therapeutic Target for Vascular Dementia

Vascular dementia (VaD) is a progressive neurodegenerative condition prevalent among elderly adults marked by cognitive decline resulting from injured and/or improperly functioning cerebrovasculature with resultant disruptions in cerebral blood flow. Currently, VaD has no specific therapeutics and the exact pathobiology is still being investigated. VaD has been shown to develop when reactive oxygen species (ROS) form from damaged targets at different levels of organization-mitochondria, endothelial cells, or cerebrovasculature. In this review, we highlight how specific ROS molecules may be important in the development of VaD and how they can be targeted as a potential therapeutic for VaD.

Turn-on fluorescent probe based on dicyanoisophorone for bioimaging and rapid detection of peroxynitrite in aqueous media

A novel dicyanoisophorone-based colorimetric fluorescent probe 3 has been prepared for recognizing peroxynitrite in aqueous conditions. A large bathochromic shift of the absorption band is observed upon titration with ONOO-, inducing a clearly visible solution color change from yellow to pale pink, which makes "naked-eye" detection possible. Moreover, probe 3 can react instantly with ONOO- and is accompanied by a significant fluorescence enhancement at 621 nm while the detection limit is as low as 37 nM. Most importantly, probe 3 exhibits high selectivity and sensitivity towards ONOO- in the presence of other competitive ions in aqueous solution. Probe 3 has also been successfully applied in living MCF-7 cells, and the results suggest that probe 3 could be applied as a potential candidate for the detection of ONOO-.

Stable oxidative posttranslational modifications alter the gating properties of RyR1

The ryanodine receptor type 1 (RyR1) is a Ca2+ release channel that regulates skeletal muscle contraction by controlling Ca2+ release from the sarcoplasmic reticulum (SR). Posttranslational modifications (PTMs) of RyR1, such as phosphorylation, S-nitrosylation, and carbonylation are known to increase RyR1 open probability (Po), contributing to SR Ca2+ leak and skeletal muscle dysfunction. PTMs on RyR1 have been linked to muscle dysfunction in diseases like breast cancer, rheumatoid arthritis, Duchenne muscle dystrophy, and aging. While reactive oxygen species (ROS) and oxidative stress induce PTMs, the impact of stable oxidative modifications like 3-nitrotyrosine (3-NT) and malondialdehyde adducts (MDA) on RyR1 gating remains unclear. Mass spectrometry and single-channel recordings were used to study how 3-NT and MDA modify RyR1 and affect Po. Both modifications increased Po in a dose-dependent manner, with mass spectrometry identifying 30 modified residues out of 5035 amino acids per RyR1 monomer. Key modifications were found in domains critical for protein interaction and channel activation, including Y808/3NT in SPRY1, Y1081/3NT and H1254/MDA in SPRY2&3, and Q2107/MDA and Y2128/3NT in JSol, near the binding site of FKBP12. Though these modifications did not directly overlap with FKBP12 binding residues, they promoted FKBP12 dissociation from RyR1. These findings provide detailed insights into how stable oxidative PTMs on RyR1 residues alter channel gating, advancing our understanding of RyR1-mediated Ca2+ release in conditions associated with oxidative stress and muscle weakness.

Diaminonaphthalene Boronic Acid (DANBA): New Approach for Peroxynitrite Sensing Site

Selective detection of reactive oxygen species (ROS) is vital for studying their role in brain diseases. Fluorescence probes can distinguish ONOO- species from other ROS; however, their selectivity toward ONOO- species depends on the ONOO- recognition group. Aryl-boronic acids and esters, which are common ONOO- recognition groups, are not selective for ONOO- over H2O2. In this study, we developed a diaminonaphthalene (DAN)-protected boronic acid as a new ONOO- recognition group that selectively reacts with ONOO- over H2O2 and other ROS. Three DAN-protected boronic acid (DANBA)-based fluorophores that emit fluorescence over visible to near-infrared (NIR) regions, Cou-BN, BVP-BN, and HDM-BN, and their aryl-boronic acid-based counterparts (Cou-BO, BVP-BO, and HDM-BO), were developed. The DANBA-based probes exhibited enhanced selectivity toward ONOO- over that of their control group, as well as universality in solution assays and in vitro experiments with PC12 cells. The NIR-emissive HDM-BN was optimized to delineate in vivo ONOO- levels in mouse brains with Parkinson's disease. This DAN-protected boronic acid belongs to a new generation of recognition groups for developing ONOO- probes, and this strategy could be extended to other common hydroxyl-containing dyes to detect ONOO- levels in complex biological systems and processes.

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.

Fluorescent probes for sensing peroxynitrite: biological applications

Peroxynitrite (ONOO-) is a quintessential reactive oxygen species (ROS) and reactive nitrogen species (RNS), renowned for its potent oxidizing and nitrifying capabilities. Under normal physiological conditions, a baseline level of ONOO- is present within the body. However, its production escalates significantly in response to oxidative stress. ONOO- is highly reactive with various biomolecules in vivo, particularly proteins, lipids, and nucleic acids, thereby playing a role in a spectrum of physiological and pathological processes, such as inflammation, cancer, neurodegenerative diseases, and cardiovascular diseases. Consequently, detecting ONOO- in vivo is of paramount importance for understanding the etiology of various diseases and facilitating early diagnosis. Fluorescent probes have become a staple in the identification of biomolecules due to their ease of use, convenience, and superior sensitivity and specificity. This review highlights the recent advancements in the development of fluorescent probes for the detection of ONOO- in diverse disease models and provides an in-depth examination of their design and application.

The nitration of SIRT6 aggravates neuronal damage during cerebral ischemia-reperfusion in rat

Ischemic stroke is a major cause of death and disability. The activation of neuronal nitric oxide synthase (nNOS) and the resulting production of nitric oxide (NO) via NMDA receptor-mediated calcium influx play an exacerbating role in cerebral ischemia reperfusion injury. The NO rapidly reacts with superoxide (O2-) to form peroxynitrite (ONOO-), a toxic molecule may modify proteins through tyrosine residue nitration, ultimately worsening neuronal damage. SIRT6 has been proven to be crucial in regulating cell proliferation, death, and aging in various pathological settings. We have previous reported that human SIRT6 tyrosine nitration decreased its intrinsic catalytic activity in vitro. However, the exact role of SIRT6 function in the process of cerebral ischemia reperfusion injury is not yet fully elucidated. Herein, we demonstrated that an increase in the nitration of SIRT6 led to reduce its enzymatic activity and aggravated hippocampal neuronal damage in a rat model of four-artery cerebral ischemia reperfusion. In addition, reducing SIRT6 nitration resulted in increase the activity of SIRT6, alleviating hippocampal neuronal damage. Moreover, SIRT6 nitration affected its downstream molecule activity such as PARP1 and GCN5, promoting the process of neuronal ischemic injury in rat hippocampus. Additionally, treatment with NMDA receptor antagonist MK801, or nNOS inhibitor 7-NI, and resveratrol (an antioxidant) diminished SIRT6 nitration and the catalytic activity of downstream molecules like PARP1 and GCN5, thereby reducing neuronal damage. Finally, in the biochemical regulation of SIRT6 activity, tyrosine 257 was essential for its activity and susceptibility to nitration. Replacing tyrosine 257 with phenylalanine in rat SIRT6 attenuated the death of SH-SY5Y neurocytes under oxygen-glucose deprivation (OGD) conditions. These results may offer further understanding of SIRT6 function in the pathogenesis of cerebral ischemic diseases.

Peroxynitrite-Responsive Near-Infrared Fluorescent Imaging Guided Synergistic Chemo-Photodynamic Therapy via Biomimetic Metal-Organic Frameworks

Peroxynitrite (ONOO-) plays a crucial role in maintaining cellular redox homeostasis and regulating diffusive processes, cellular transport, and signal transduction. Extensive studies have revealed that increased ONOO- levels during tumor progression are associated with heightened levels of oxidative stress. However, current methods lack noninvasive visualization, immediate reporting, and highly sensitive fluorescence sensing. In light of this, we have designed a biomimetic fluorescent nanoplatform, named Z-C-T@CM, for peroxynitrite-responsive near-infrared fluorescent imaging guided cancer treatment. The nanoplatform comprises tetrakis(4-carboxyphenyl) porphyrin (TCPP) and curcumin (CCM) encapsulated within a zeolitic imidazolate framework-8 (ZIF-8), which is coated with a mouse breast cancer cell membrane for enhanced biocompatibility and targeting, while evading immune clearance. In vitro experimental results demonstrate that the as-prepared nanoplatform exhibits enhanced near-infrared fluorescence emission upon exposure to ONOO-, indicating a significant potential for noninvasive in vivo imaging of ONOO- during tumor progression. Additionally, Z-C-T@CM readily degrades in the tumor microenvironment, releasing TCPP and CCM, enabling a synergistic chemo-photodynamic therapy with near-infrared illumination. Further investigations indicate that Z-C-T@CM efficiently stimulates a tumor immune response and facilitates therapeutic efficiency. Collectively, this work introduces a novel noninvasive strategy for ONOO- detection, shedding new light on the integration of cancer diagnosis and efficient treatment.

Recent progress in organelle-targeting fluorescent probes for the detection of peroxynitrite

Peroxynitrite (ONOO-), as an important reactive nitrogen species, plays a pivotal role in the regulation of intracellular redox homeostasis, signal transduction, cell growth and metabolism, and other physiological processes. Organelles are important for regulating ONOO-, and the dysregulation of ONOO- in organelles is closely related to various diseases. Therefore, it is essential to monitor ONOO- in cellular organelles, including mitochondria, lysosome, endoplasmic reticulum (ER), Golgi apparatus, and lipid droplets. However, the latest advances in organelle-targeting ONOO- fluorescent probes have not been reviewed systematically. In this review, we focus on the design, sensing mechanism, and organelle-targeting imaging applications of ONOO- fluorescent probes that were reported since 2018. This review will help to facilitate the comprehension of organelle-targeting fluorescent probes for the detection of ONOO-.

Association of Uric Acid, High-Sensitivity C-Reactive Protein, and 90-Day Risk of Poor Function Outcome in Patients with Ischemic Stroke or Transient Ischemic Attacks

Aim

The interaction between inflammatory biomarkers (high-sensitivity C-reactive protein, hsCRP) and antioxidants (uric acid, UA) regarding prognosis after ischemic stroke or transient ischemic attack (TIA) remains inadequately explored. This study aimed to assess (1) the individual and joint effects of hsCRP and UA, and (2) the neuroprotective role of UA in patients with elevated hsCRP levels concerning poor functional outcomes at 90 days.

Methods

A prospective cohort study was conducted involving 2140 consecutive ischemic stroke or TIA patients with hsCRP and UA levels. The primary outcome was defined as a poor functional outcome, indicated by a modified Rankin Scale (mRS) score of 3-6 at 90 days, with a shift in the mRS score as a secondary outcome. Logistic regression and propensity score (PS) analyses were employed to ensure robustness.

Results

Poor functional outcome occurred in 345 (16.1%) patients. Individual effects found that the highest quartiles of hsCRP (adjusted OR = 3.090; 95% CI 2.150-4.442) and UA (adjusted OR = 0.671; 95% CI 0.551-0.883) were associated with increased or decreased risk of poor functional outcome, respectively. Joint effects (adjusted OR = 3.994; 95% CI 2.758-5.640) between hsCRP and UA on the primary outcome were more apparent in patients with high hsCRP levels (hsCRP > 1.60 mg/L) and low UA levels (UA ≤ 291.85 µmol/L). For the patients with high hsCRP levels, patients with low UA levels had a higher risk of primary and secondary outcomes, compared with those with high UA levels, after unadjusted or adjusted for hsCRP. Similar and reliable results were observed in PS-based models.

Conclusion

In patients with ischemic stroke or TIA, joint high levels of hsCRP and low UA levels significantly correlate with increased risk of poor functional outcome at 90 days. In addition, high UA levels could reduce the risk of poor functional outcome for patients with high hsCRP levels.

Dual NIR-channel fluorescent probe for detecting ONOO- in vitro and vivo

As one of endogenous reactive oxygen species (ROS), peroxynitrite (ONOO-) performs various functions in both pathological and physiological mechanisms. In this work, an optical and near-infrared (NIR) fluorescent probe (NX), which based on 3-dihydro-1H-xanthene and 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF) group was designed and prepared to detect ONOO-. This probe revealed an obvious optical and a fluorescent response when ONOO- was present and it exhibited higher selectivity over other ROS. Especially, the dual NIR fluorescence changes at 660 and 800 nm allowed quantitative detection of ONOO- in the range of 15-40 μM, and the detection limit was 82 nM. Finally, the probe was effectively employed to visualize exogenous and endogenous ONOO- in HepG2 cells and zebrafish, respectively. All the results indicated the dual NIR-channel probe could serve as a potent detecting tools in studying ONOO- in vitro and in vivo.

Energy metabolism dysregulation, cerebrovascular aging, and time-restricted eating: Current evidence and proof-of-concept findings

Dysregulated energy metabolism is a hallmark of aging, including brain aging; thus, strategies to restore normal metabolic regulation are at the forefront of aging research. Intermittent fasting, particularly time-restricted eating (TRE), is one of these strategies. Despite its well-established effectiveness in improving metabolic outcomes in older adults, the effect of TRE on preserving or improving cerebrovascular health during aging remains underexplored. We explored how aging itself affects energy metabolism and contextualized these age-related changes to cerebrovascular health. We also conducted a literature search on PubMed and Scopus to identify and summarize current studies on TRE in older adults. Finally, we provided preliminary data from our proof-of-concept pilot trial on the effect of 6-month TRE on cerebrovascular health in older adults. Current evidence shows the potential of TRE to improve energy metabolism and physiological outcomes in older adults. TRE may improve cerebrovascular function indirectly due to its effect on glucose homeostasis. However, to date, direct evidence of the effect of TRE on cerebrovascular parameters is lacking. TRE is a well-tolerated and promising dietary intervention for promoting and maintaining cerebrovascular health in older adults. Further studies on TRE in older adults must be better controlled for energy balance to elucidate its independent effects from those of caloric restriction.

Sulfur-based fluorescent probes for biological analysis: A review

The widespread adoption of small-molecule fluorescence detection methodologies in scientific research and industrial contexts can be ascribed to their inherent merits, including elevated sensitivity, exceptional selectivity, real-time detection capabilities, and non-destructive characteristics. In recent years, there has been a growing focus on small-molecule fluorescent probes engineered with sulfur elements, aiming to detect a diverse array of biologically active species. This review presents a comprehensive survey of sulfur-based fluorescent probes published from 2017 to 2023. The diverse repertoire of recognition sites, including but not limited to N, N-dimethylthiocarbamyl, disulfides, thioether, sulfonyls and sulfoxides, thiourea, thioester, thioacetal and thioketal, sulfhydryl, phenothiazine, thioamide, and others, inherent in these sulfur-based probes markedly amplifies their capacity for detecting a broad spectrum of analytes, such as metal ions, reactive oxygen species, reactive sulfur species, reactive nitrogen species, proteins, and beyond. Owing to the individual disparities in the molecular structures of the probes, analogous recognition units may be employed to discern diverse substrates. Subsequent to this classification, the review provides a concise summary and introduction to the design and biological applications of these probe molecules. Lastly, drawing upon a synthesis of published works, the review engages in a discussion regarding the merits and drawbacks of these fluorescent probes, offering guidance for future endeavors.

Hybridized and engineered microbe for catalytic generation of peroxynitrite and cancer immunotherapy under sonopiezo initiation

Living therapeutics is an emerging antitumor modality by living microorganisms capable of selective tropism and effective therapeutics. Nevertheless, primitive microbes could only present limited therapeutic functionalities against tumors. Hybridization of the microbes with multifunctional nanocatalysts is of great significance to achieve enhanced tumor catalytic therapy. In the present work, nitric oxide synthase (NOS)-engineered Escherichia coli strain MG1655 (NOBac) was used to hybridize with the sonopiezocatalytic BaTiO3 nanoparticles (BTO NPs) for efficient tumor-targeted accumulation and antitumor therapy. Under ultrasound irradiation, superoxide anions created by the piezocatalytic reaction of BTO NPs could immediately react with nitric oxide (NO) generated from NOBac to produce highly oxidative peroxynitrite ONOO- species in cascade, resulting in robust tumor piezocatalytic therapeutic efficacy, prompting prominent and sustained antitumoral immunoactivation simultaneously. The present work presents a promising cancer immunotherapy based on the engineered and hybridized microbes for highly selective and sonopiezo-controllable tumor catalytic therapy.

Cold Exposure Therapy Sensitizes Nanodrug-Mediated Radioimmunotherapy of Breast Cancer

Cold exposure (CE) therapy can quickly induce tumor starvation by brown adipose tissue (BAT) thermogenesis. Exploring the combined antitumor mechanism of CE and traditional therapies (such as radiotherapy (RT)) is exciting and promising. In this study, we investigated the effect of CE in combination with nitric oxide (NO) gas therapy on sensitizing tumors to RT and promoting tumor radio-immunotherapy. We first constructed a liposome (SL) loaded with the NO prodrug S-nitroso-N-acetylpenicillamine (SNAP). When SL is injected, the glutathione (GSH) within the tumor region promotes the release of NO from SNAP. Subsequently, the superoxide anion produced by RT reacts with NO to generate peroxynitrite (ONOO-), which has strong oxidative properties and induces cell death. Meanwhile, the mice were exposed to a CE environment of 4 °C. CE-mediated BAT thermogenesis induced tumor starvation, which led to a decrease in ATP and GSH content within the tumor as well as an improvement in the hypoxic microenvironment and a decrease in myeloid-derived suppressor cells. All of the above have promoted the effectiveness of RT and activated the systemic antitumor immunity. In the bilateral tumor experiment, treatment of the primary tumor inhibited the growth of the distant tumor and promoted the infiltration of CD8+ T cells into the tumor. These findings reveal that the synergy of CE, NO gas therapy, and RT could confer high effective anticancer effects, providing possibilities in personalized cancer treatment.

Effect of 5β-dihydrotestosterone on vasodilator function and on cell proliferation

Aging is one of the main factors associated with cardiovascular diseases. Androgens exert beneficial effects on the cardiovascular system and testosterone (TES) replacement therapy improves cardiometabolic risk factors. However, TES is contraindicated in patients with prostate cancer due to its proliferative effects on prostatic tumor cells. Additionally, TES and its reduced metabolites 5α- and 5β-dihydrotestosterone (5α-DHT and 5β-DHT) exert vasodilatory effects. Since androgen levels decrease during aging and 5β-DHT lacks genomic effects, this study is focused on analyzing its effect on vasodilator function and the proliferation rate of prostatic tumor and vascular smooth muscle cells. To study the vascular function, mesenteric arteries from aged-orchidectomized Sprague-Dawley rats were used. Mesenteric segments were divided into one control (without treatment) and three groups with the androgens (10 nM, 30 min) to analyze: acetylcholine- and sodium nitroprusside-induced responses and nitric oxide and superoxide anion production. To analyze cell proliferation, the effect of androgens on cell viability was determined. The results showed that 5β-DHT improves vasodilator function in arteries from aged-orchidectomized rats and induces antioxidant action, while the proliferation rate of the androgen-dependent prostatic tumor cells remains unaltered. These results make 5β-DHT a promising therapeutic agent for the treatment of cardiovascular pathologies.

Multifunctional Molecular Hybrids Photoreleasing Nitric Oxide: Advantages, Pitfalls, and Opportunities

The multifaceted role nitric oxide (NO) plays in human physiology and pathophysiology has opened new scenarios in biomedicine by exploiting this free radical as an unconventional therapeutic against important diseases. The difficulties in handling gaseous NO and the strict dependence of the biological effects on its doses and location have made the light-activated NO precursors, namely NO photodonors (NOPDs), very appealing by virtue of their precise spatiotemporal control of NO delivery. The covalent integration of NOPDs and additional functional components within the same molecular skeleton through suitable linkers can lead to an intriguing class of multifunctional photoactivatable molecular hybrids. In this Perspective, we provide an overview of the recent advances in these molecular constructs, emphasizing those merging NO photorelease with targeting, fluorescent reporting, and phototherapeutic functionalities. We will highlight the rational design behind synthesizing these molecular hybrids and critically describe the advantages, drawbacks, and opportunities they offer in biomedical research.

Molecular Logic Gate for Sensing pH/Peroxynitrite with Potential Applications in Cisplatin Treatment

Cisplatin is a common chemotherapy drug for multiple solid tumors; however, due to the nitrification of peroxynitrite (ONOO-), a series of side effects seriously affect its dose and efficacy. Considering that the reactivity of ONOO- is significantly affected by pH in vitro, revealing their roles in living cells contributes to understanding the side-effect process induced by cisplatin. Herein, we present a near-infrared fluorescent logic gate for sensing pH/ONOO-, which can accurately discriminate four scenarios (no analyte, analyte H+ alone, analyte ONOO- alone, and H+ + ONOO-) and which one comes first. With this probe, the significant roles of pH and ONOO- in cisplatin treatment are disclosed, in which the cell account shows a dramatic reduction accompanied by decreased pH and upregulated ONOO- levels. By artificially recovering the pH, the ONOO- content and cell account can maintain a stable state, possibly due to the protection from acidification and nitration. This work provides an ideal pH/ONOO- logical sensor for revealing their potential roles under cisplatin, which is expected to proffer new insights into more related diseases and drug research.

Nitric oxide releasing coatings for the prevention of viral and bacterial infections

Healthcare associated infections (HCAI) represent a significant burden worldwide contributing to morbidity and mortality and result in substantial economic consequences equating to billions annually. Although the impacts of HCAI have been felt for many years, the coronavirus pandemic has had a profound effect, escalating rates of HCAI, even with extensive preventative measures such as vaccination, personal protective equipment, and deep cleaning regimes. Therefore, there is an urgent need for new solutions to mitigate this serious health emergency. In this paper, the fabrication of nitric oxide (NO) releasing dual action polymer coatings for use in healthcare applications is described. The coatings are doped with the NO donor S-nitroso-N-acetylpenicillamine (SNAP) and release high payloads of NO in a sustained manner for in excess of 50 hours. These coatings are extensively characterized in multiple biologically relevant solutions and the antibacterial/antiviral efficacy is studied. For the first time, we assess antibacterial activity in a time course study (1, 2, 4 and 24 h) in both nutrient rich and nutrient poor conditions. Coatings exhibit excellent activity against Pseudomonas aeruginosa and methicillin resistant Staphylococcus aureus (MRSA), with up to complete reduction observed over 24 hours. Additionally, when tested against SARS-CoV-2, the coatings significantly reduced active virus in as little as 10 minutes. These promising results suggest that these coatings could be a valuable addition to existing preventative measures in the fight against HCAIs.

Insight into the surface discharge cold plasma efficient inactivation of Pseudomonas fluorescens in water based on exogenous reactive oxygen and nitrogen species: Synergistic mechanism and energy benefits

As well known, surface discharge cold plasma has efficient inactivation ability and a variety of RONS are main active particles for inactivation, but their synergistic mechanism is still not clear. Therefore, surface discharge cold plasma system was applied to treat Pseudomonas fluorescens to study bacterial inactivation mechanism and energy benefit. Results showed that energy efficiency was directly proportional to applied voltage and inversely proportional to initial concentration. Cold plasma treatment for 20 min was inactivated by approximately > 4-log10Pseudomonas fluorescens and application of •OH and 1O2 scavengers significantly improved survival rate. In addition, •OH and 1O2 destroyed cell membrane structure and membrane permeability, which promoted diffusion of RONS into cells and affecting energy metabolism and antioxidant capacity, leading to bacterial inactivation. Furthermore, accumulation of intracellular NO and ONOOH was related to infiltration of exogenous RNS, while accumulation of •OH, H2O2, 1O2, O2- was the result of joint action of endogenous and exogenous ROS. Transcriptome analysis revealed that different RONS of cold plasma were responsible for Pseudomonas fluorescens inactivation and related to activation of intracellular antioxidant defense system and regulation of genes expression related to amino acid metabolism and energy metabolism, which promoting cellular process, catalytic activity and other biochemical pathways.

Selective nitration of Hsp90 acts as a metabolic switch promoting tumor cell proliferation

Tumors develop in an oxidative environment characterized by peroxynitrite production and downstream protein tyrosine (Y) nitration. We showed that tyrosine nitration supports schwannoma cell proliferation and regulates cell metabolism in the inheritable tumor disorder NF2-related Schwannomatosis (NF2-SWN). Here, we identified the chaperone Heat shock protein 90 (Hsp90) as the first nitrated protein that acts as a metabolic switch to promote schwannoma cell proliferation. Doubling the endogenous levels of nitrated Hsp90 in schwannoma cells or supplementing nitrated Hsp90 into normal Schwann cells increased their proliferation. Metabolically, nitration on either Y33 or Y56 conferred Hsp90 distinct functions; nitration at Y33 (Hsp90NY33) down-regulated mitochondrial oxidative phosphorylation, while nitration at Y56 (Hsp90NY56) increased glycolysis by activating the purinergic receptor P2X7 in both schwannoma and normal Schwann cells. Hsp90NY33 and Hsp90NY56 showed differential subcellular and spatial distribution corresponding with their metabolic and proliferative functions in schwannoma three-dimensional cell culture models. Collectively, these results underscore the role of tyrosine nitration as a post-translational modification regulating critical cellular processes. Nitrated proteins, particularly nitrated Hsp90, emerge as a novel category of tumor-directed therapeutic targets.