Nitric oxide protects intestinal mucosal barrier function and prevents acute graft rejection after intestinal transplantation: A mini-review.

Intestinal transplantation is a complex technical procedure that provides patients suffering from end-stage intestinal failure an opportunity to enjoy improved quality of life, nutrition and survival. Compared to other types of organ transplants, it is a relatively new advancement in the field of organ transplantation. Nevertheless, great advances have been made over the past few decades to the present era, including the use of ischemic preconditioning, gene therapy, and addition of pharmacological supplements to preservation solutions. However, despite these strides, intestinal transplantation is still a challenging endeavor due to several factors. Notable among them is ischemia-reperfusion injury (IRI), which results in loss of cellular integrity and mucosal barrier function. In addition, IRI causes graft failure, delayed graft function, and decreased graft and recipient survival. This has necessitated the search for novel therapeutic avenues and improved transplantation protocols to prevent or attenuate intestinal IRI. Among the many candidate agents that are being investigated to combat IRI and its associated complications, nitric oxide (NO). NO is an endogenously produced gaseous signaling molecule with several therapeutic properties. The purpose of this mini-review is to discuss IRI and its related complications in intestinal transplantation, and NO as an emerging pharmacological tool against this challenging pathological condition. i.

Evaluation of a biomarker (NO) dynamics in inflammatory zebrafish and periodontitis saliva samples via a fast-response and sensitive fluorescent probe.

Many pathological processes include nitric oxide (NO), a signaling transduction molecule. Tumors, cardiovascular, cerebrovascular, neurodegenerative, and other illnesses are linked to abnormal NO levels. Thus, evaluating NO levels in vitro and in vivo is crucial for studying chemical biology process of associated disorders. This work devised and manufactured a coumarin-based fluorescent probe ZPS-NO to detect nitric oxide (NO). The reaction between ZPS-NO and NO produced a highly selective and sensitive optical response that caused a powerful fluorescence "turn-on" effect with a ultra-low NO detection limit of 14.5 nM. Furthermore, the probe was applied to sense and image NO in living cells and inflammatory model of zebrafish, as well as to detect NO in periodontitis patients' saliva samples. We anticipate that probe ZPS-NO will serve as a practical and effective tool for assessing the interactions and evaluation of periodontitis development.

Identification of new multi-substituted 1H-pyrazolo[3,4-c]pyridin-7(6H)-ones as soluble guanylyl cyclase (sGC) stimulators with vasoprotective and anti-inflammatory activities.

Herein, we describe the rational design, synthesis and in vitro functional characterization of new heme-dependent, direct soluble guanylyl cyclase (sGC) agonists. These new compounds bear a 1H-pyrazolo[3,4-c]pyridin-7(6H)-one skeleton, modified to enable efficient sGC binding and stimulation. To gain insights into structure-activity relationships, the N6-alkylation of the skeleton was explored, while a pyrimidine ring, substituted with various C5'-polar groups, was installed at position C3. Among the newly synthesized 1H-pyrazolo[3,4-c]pyridin-7(6H)-ones, derivatives 14b, 15b and 16a display characteristic features of sGC "stimulators" in A7r5 vascular smooth muscle cells in vitro. They strongly synergize with the NO donor, sodium nitroprusside (SNP) in inducing cGMP generation in a manner that requires the presence of a reduced heme moiety associated with sGC, and elevate the cGMP-responsive phosphorylation of the protein VASP at Ser239. In line with their sGC stimulating capacity, docking calculations of derivatives 16a, 15(a-c) on a cryo-EM structure of human sGC (hsGC) in an ΝΟ-activated state indicated the implication of 1H-pyrazolo[3,4-c]pyridin-7(6H)-one skeleton in efficient bonding interactions with the recently identified region that binds known sGC stimulators, while the presence of either a N6-H or N6-methyl group pointed to enhanced binding affinity. Moreover, the in vitro functional effects of our newly identified sGC stimulators were compatible with a beneficial role in vascular homeostasis. Specifically, derivative 14b reduced A7r5 cell proliferation, while 16a dampened the expression of adhesion molecules ICAM-1 and P/E-Selectin in Human Umbilical Vein Endothelial Cells (HUVECs), as well as the subsequent adhesion of U937 leukocytes to the HUVECs, triggered by tumor necrosis factor alpha (TNF-α) or interleukin-1 beta (IL-1ß). The fact that these compounds elevate cGMP only in the presence of NO may indicate a novel way of interaction with the enzyme and may make them less prone than other direct sGC agonists to induce characteristic hypotension in vivo.

Panobinostat, a Histone Deacetylase Inhibitor, Reduces LPS-Induced Expression of Inducible Nitric Oxide Synthase in Rat Immortalized Microglia HAPI Cells.

Microglia, resident immune cells in the central nervous system (CNS), play a critical role in maintaining CNS homeostasis. However, microglia activated in response to brain injury produce various inflammatory mediators, including nitric oxide (NO) and proinflammatory cytokines, leading to considerable neuronal damage. NO generated by inducible NO synthase (iNOS) rapidly reacts with superoxide to form a highly toxic product, peroxynitrite. Therefore, iNOS is considered to be a putative therapeutic target for cerebral ischemia. Here, we examined the effects of panobinostat (Pano), a histone deacetylase inhibitor, on lipopolysaccharide (LPS)-induced iNOS expression using rat immortalized microglia HAPI cells. Pano inhibited LPS-induced expression of iNOS mRNA and NO production in a dose-dependent manner; however, it had little effect on the LPS-induced activation of c-Jun N-terminal kinase (JNK) and p38 or nuclear translocation of nuclear factor-κB (NF-κB). The interferon-ß (IFN-ß)/signal transducer and activator of transcription (STAT) pathway is essential for LPS-induced iNOS expression in macrophages/microglia. We also examined the effects of Pano on LPS-induced IFN-ß signaling. Pano markedly inhibited LPS-induced IFN-ß expression and subsequent tyrosine phosphorylation of STAT1. However, the addition of IFN-ß restored the decreased STAT1 phosphorylation but not the decreased iNOS expression. In addition, Pano inhibited the LPS-increased expression of octamer binding protein-2 and interferon regulatory factor 9 responsible for iNOS expression, but IFN-ß addition also failed to restore the decreased expression of these factors. Thus, we conclude that the inhibitory effects of Pano are due not only to the inhibition of the IFN-ß/STAT axis but also to the downregulation of other factors not involved in this axis.

3-Hydroxy-3-(2-oxopropyl)indolin-2-one, a product of a human-derived Enterocloster strain, is an inhibitor of nitric oxide production.

When cultured anaerobically, Enterocloster sp. RD014215 was found to produce 1. Using nuclear magnetic resonance and mass spectroscopy, the planar structure of 1 was determined to be 3-hydroxy-3-(2-oxopropyl)indolin-2-one. The chirality of 1 was implied as S by comparing the optical rotation value of 1 with literature reports of the synthesized compounds. To our knowledge, this work represents the first discovery of the metabolite produced by Enterocloster strain. 1 exhibited inhibition of nitric oxide (NO) production, demonstrating a 50% inhibitory activity (IC50) of 34 µm for NO production by murine macrophage cells subjected to lipopolysaccharide stimulation.

Tryptophan Metabolism in Obesity: The Indoleamine 2,3-Dioxygenase-1 Activity and Therapeutic Options.

Obesity activates both innate and adaptive immune responses in adipose tissue. Adipose tissue macrophages are functional antigen-presenting cells that promote the proliferation of interferon-gamma (IFN-γ)-producing cluster of differentiation (CD)4+ T cells in adipose tissue of obese subjects. The increased formation of neopterin and degradation of tryptophan may result in decreased T-cell responsiveness and lead to immunodeficiency. The activity of inducible indoleamine 2,3-dioxygenase-1 (IDO1) plays a major role in pro-inflammatory, IFN-γ-dominated settings. The expression of several kynurenine pathway enzyme genes is significantly increased in obesity. IDO1 in obesity shifts tryptophan metabolism from serotonin and melatonin synthesis to the formation of kynurenines and increases the ratio of kynurenine to tryptophan as well as with neopterin production. Reduction in serotonin (5-hydroxytryptamine; 5-HT) production provokes satiety dysregulation that leads to increased caloric uptake and obesity. According to the monoamine-deficiency hypothesis, a deficiency of cerebral serotonin is involved in neuropsychiatric symptomatology of depression, mania, and psychosis. Indeed, bipolar disorder (BD) and related cognitive deficits are accompanied by a higher prevalence of overweight and obesity. Furthermore, the accumulation of amyloid-ß in Alzheimer's disease brains has several toxic effects as well as IDO induction. Hence, abdominal obesity is associated with vascular endothelial dysfunction. kynurenines and their ratios are prognostic parameters in coronary artery disease. Increased kynurenine/tryptophan ratio correlates with increased intima-media thickness and represents advanced atherosclerosis. However, after bariatric surgery, weight reduction does not lead to the normalization of IDO1 activity and atherosclerosis. IDO1 is involved in the mechanisms of immune tolerance and in the concept of tumor immuno-editing process in cancer development. Serum IDO1 activity is still used as a parameter in cancer development and growth. IDO-producing tumors show a high total IDO immunostaining score, and thus, using IDO inhibitors, such as Epacadostat, Navoximod, and L isomer of 1-methyl-tryptophan, seems an important modality for cancer treatment. There is an inverse correlation between serum folate concentration and body mass index, thus folate deficiency leads to hyperhomocysteinemia-induced oxidative stress. Immune checkpoint blockade targeting cytotoxic T-lymphocyte-associated protein-4 synergizes with imatinib, which is an inhibitor of mitochondrial folate-mediated one-carbon (1C) metabolism. Antitumor effects of imatinib are enhanced by increasing T-cell effector function in the presence of IDO inhibition. Combining IDO targeting with chemotherapy, radiotherapy and/or immunotherapy, may be an effective tool against a wide range of malignancies. However, there are some controversial results regarding the efficacy of IDO1 inhibitors in cancer treatment.

Endothelial Dysfunction in Obesity and Therapeutic Targets.

Parallel to the increasing prevalence of obesity in the world, the mortality from cardiovascular disease has also increased. Low-grade chronic inflammation in obesity disrupts vascular homeostasis, and the dysregulation of adipocyte-derived endocrine and paracrine effects contributes to endothelial dysfunction. Besides the adipose tissue inflammation, decreased nitric oxide (NO)-bioavailability, insulin resistance (IR), and oxidized low-density lipoproteins (oxLDLs) are the main factors contributing to endothelial dysfunction in obesity and the development of cardiorenal metabolic syndrome. While normal healthy perivascular adipose tissue (PVAT) ensures the dilation of blood vessels, obesity-associated PVAT leads to a change in the profile of the released adipo-cytokines, resulting in a decreased vasorelaxing effect. Higher stiffness parameter ß, increased oxidative stress, upregulation of pro-inflammatory cytokines, and nicotinamide adenine dinucleotide phosphate (NADP) oxidase in PVAT turn the macrophages into pro-atherogenic phenotypes by oxLDL-induced adipocyte-derived exosome-macrophage crosstalk and contribute to the endothelial dysfunction. In clinical practice, carotid ultrasound, higher leptin levels correlate with irisin over-secretion by human visceral and subcutaneous adipose tissues, and remnant cholesterol (RC) levels predict atherosclerotic disease in obesity. As a novel therapeutic strategy for cardiovascular protection, liraglutide improves vascular dysfunction by modulating a cyclic adenosine monophosphate (cAMP)-independent protein kinase A (PKA)-AMP-activated protein kinase (AMPK) pathway in PVAT in obese individuals. Because the renin-angiotensin-aldosterone system (RAAS) activity, hyperinsulinemia, and the resultant IR play key roles in the progression of cardiovascular disease in obesity, RAAS-targeted therapies contribute to improving endothelial dysfunction. By contrast, arginase reciprocally inhibits NO formation and promotes oxidative stress. Thus, targeting arginase activity as a key mediator in endothelial dysfunction has therapeutic potential in obesity-related vascular comorbidities. Obesity-related endothelial dysfunction plays a pivotal role in the progression of type 2 diabetes (T2D). The peroxisome proliferator-activated receptor gamma (PPARγ) agonist, rosiglitazone (thiazolidinedione), is a popular drug for treating diabetes; however, it leads to increased cardiovascular risk. Selective sodium-glucose co-transporter-2 (SGLT-2) inhibitor empagliflozin (EMPA) significantly improves endothelial dysfunction and mortality occurring through redox-dependent mechanisms. Although endothelial dysfunction and oxidative stress are alleviated by either metformin or EMPA, currently used drugs to treat obesity-related diabetes neither possess the same anti-inflammatory potential nor simultaneously target endothelial cell dysfunction and obesity equally. While therapeutic interventions with glucagon-like peptide-1 (GLP-1) receptor agonist liraglutide or bariatric surgery reverse regenerative cell exhaustion, support vascular repair mechanisms, and improve cardiometabolic risk in individuals with T2D and obesity, the GLP-1 analog exendin-4 attenuates endothelial endoplasmic reticulum stress.

LW-1 induced resistance to TMV in tobacco was mediated by nitric oxide and salicylic acid pathway.

The objective of this study was to investigate the mechanism underlying LW-1-induced resistance to TMV in wild-type and salicylic acid (SA)-deficient NahG transgenic tobacco plants. Our findings revealed that LW-1 failed to induce antivirus infection activity and increase SA content in NahG tobacco, indicating the crucial role of SA in these processes. Meanwhile, LW-1 triggered defense-related early-signaling nitric oxide (NO) generation, as evidenced by the emergence of NO fluorescence in both types of tobacco upon treatment with LW-1, however, NO fluorescence was stronger in NahG compared to wild-type tobacco. Notably, both of them were eliminated by the NO scavenger cPTIO, which also reversed LW-1-induced antivirus activity and the increase of SA content, suggesting that NO participates in LW-1-induced resistance to TMV, and may act upstream of the SA pathway. Defense-related enzymes and genes were detected in tobacco with or without TMV inoculation, and the results showed that LW-1 regulated both enzyme activity (ß-1,3-glucanase [GLU], catalase [CAT] and phenylalanine ammonia-lyase [PAL]) and gene expression (PR1, PAL, WYKY4) through NO signaling in both SA-dependent and SA-independent pathways.

Exploring the Anti-Inflammatory Potential of Australian Native Plants Based on their Ethnopharmacological Knowledge.

Inflammation represents the inherent protective reaction of the human body to various harmful agents and noxious stimuli. Standard anti-inflammatory therapy including nonsteroidal anti-inflammatory drugs are associated with several side effects. In the past decades, people rely on medicinal plants for the treatment of inflammation. The traditional utilization of medicinal plants is regarded as a safe, cost-effective, and broadly accepted approach. In this study, anti-inflammatory activity of plants traditionally utilized by the D'harawal people in Australia has been assessed in vitro. Eighty Australian native plants were screened based on the Dharawal Pharmacopeia for their inhibitory effect on the nitric oxide (NO) production in lipopolysaccharides (LPS) and interferon (IFN)-γ stimulated RAW 264.7 murine macrophages for their anti-inflammatory activity. From the eighty ethanolic extracts screened, seventeen displayed potent NO inhibition with an IC50 recorded below 15 µg/mL. The aim of this review was to utilise the ethnopharmacological knowledge and to correlate the anti-inflammatory activity of the seventeen plants with either their known or unknown phytochemicals reported in the literature. In doing so, we have created a snapshot of Australian native plant candidates that warrant further chemical investigation associated with their anti-inflammatory activity.

Nitric Oxide-Loaded Bioinspired Lipoprotein Normalizes Tumor Vessels To Improve Intratumor Delivery and Chemotherapy of Albumin-Bound Paclitaxel Nanoparticles.

The disorganized vasculatures in tumors represent a substantial challenge of intratumor nanomedicine delivery to exert the anticancer effects. Herein, we rationally designed a glutathione (GSH)-activated nitric oxide (NO) donor loaded bioinspired lipoprotein system (NO-BLP) to normalize tumor vessels and then promote the delivery efficiency of sequential albumin-bound paclitaxel nanoparticles (PAN) in tumors. NO-BLP exhibited higher tumor accumulation and deeper penetration versus the counterpart liposomal formulation (NO-Lipo) in 4T1 breast cancer tumors, thus producing notable vascular normalization efficacy and causing a 2.33-fold increase of PAN accumulation. The sequential strategy of NO-BLP plus PAN resulted in an 81.03% inhibition of tumor growth in 4T1 tumors, which was better than the NO-BLP monotherapy, PAN monotherapy, and the counterpart NO-Lipo plus PAN treatment. Therefore, the bioinspired lipoprotein of NO-BLP provides an encouraging platform to normalize tumor vessels and promote intratumor delivery of nanomedicines for effective cancer treatment.

Long-Term Exposure of Cultured Astrocytes to High Glucose Impact on Their LPS-Induced Activation.

Diabetes mellitus is associated with various complications, mainly caused by the chronic exposure of the cells to high glucose (HG) concentrations. The effects of long-term HG exposure in vitro accompanied by lipopolysaccharide (LPS) application on astrocytes are relatively unknown. We used cell medium with normal (NG, 5.5 mM) or high glucose (HG, 25 mM) for rat astrocyte cultures and measured the release of NO, IL-6, ß-hexosaminidase and cell survival in response to LPS. We first demonstrated that HG long-term incubation of astrocytes increased the release of ß-hexosaminidase without decreasing MTT-detected cell survival, suggesting that there is no cell membrane damage or astrocyte death but could be lysosome exocytosis. Different from what was observed for NG, all LPS concentrations tested at HG resulted in an increase in IL-6, and this was detected for both 6 h and 48 h treatments. Interestingly, ß-hexosaminidase level increased after 48 h of LPS and only at HG. The NO release from astrocytes also increased with LPS application at HG but was less significant. These data endorsed the original hypothesis that long-term hyperglycemia increases proinflammatory activation of astrocytes, and ß-hexosaminidase could be a specific marker of excessive activation of astrocytes associated with exocytosis.

The Key Targets of NO-Mediated Post-Translation Modification (PTM) Highlighting the Dynamic Metabolism of ROS and RNS in Peroxisomes.

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

Replicative Endothelial Cell Senescence May Lead to Endothelial Dysfunction by Increasing the BH2/BH4 Ratio Induced by Oxidative Stress, Reducing BH4 Availability, and Decreasing the Expression of eNOS.

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

Impacts assessment of nitrification inhibitors on U.S. agricultural emissions of reactive nitrogen gases.

Fertilizer-intensive agriculture leads to emissions of reactive nitrogen (Nr), posing threats to climate via nitrous oxide (N2O) and to air quality and human health via nitric oxide (NO) and ammonia (NH3) that form ozone and particulate matter (PM) downwind. Adding nitrification inhibitors (NIs) to fertilizers can mitigate N2O and NO emissions but may stimulate NH3 emissions. Quantifying the net effects of these trade-offs requires spatially resolving changes in emissions and associated impacts. We introduce an assessment framework to quantify such trade-off effects. It deploys an agroecosystem model with enhanced capabilities to predict emissions of Nr with or without the use of NIs, and a social cost of greenhouse gas to monetize the impacts of N2O on climate. The framework also incorporates reduced-complexity air quality and health models to monetize associated impacts of NO and NH3 emissions on human health downwind via ozone and PM. Evaluation of our model against available field measurements showed that it captured the direction of emission changes but underestimated reductions in N2O and overestimated increases in NH3 emissions. The model estimated that, averaged over applicable U.S. agricultural soils, NIs could reduce N2O and NO emissions by an average of 11% and 16%, respectively, while stimulating NH3 emissions by 87%. Impacts are largest in regions with moderate soil temperatures and occur mostly within two to three months of N fertilizer and NI application. An alternative estimate of NI-induced emission changes was obtained by multiplying the baseline emissions from the agroecosystem model by the reported relative changes in Nr emissions suggested from a global meta-analysis: -44% for N2O, -24% for NO and +20% for NH3. Monetized assessments indicate that on an annual scale, NI-induced harms from increased NH3 emissions outweigh (8.5-33.8 times) the benefits of reducing NO and N2O emissions in all agricultural regions, according to model-based estimates. Even under meta-analysis-based estimates, NI-induced damages exceed benefits by a factor of 1.1-4. Our study highlights the importance of considering multiple pollutants when assessing NIs, and underscores the need to mitigate NH3 emissions. Further field studies are needed to evaluate the robustness of multi-pollutant assessments.

Extract of Chenopodium album lowers blood pressure in rats through endothelium-dependent and -independent vasorelaxation.

OBJECTIVES: To investigate the antihypertensive effect of crude extract of Chenopodium album (Ca.Cr), based on its medicinal use in hypertension. METHODS: Ca.Cr and its fractions were tested in-vivo in normotensive anesthetized rats for blood pressure-lowering effect. In-vitro experiments were performed on isolated rat aortae to explore the vascular mechanism(s). RESULTS: In normotensive anesthetized rats, Ca.Cr produced a dose-dependent (1-300mg/kg) fall (30%mmHg) in mean arterial pressure (MAP). Among the fractions, nHexane was the most potent (46% fall). In rat aortic rings precontracted with phenylephrine (PE), Ca.Cr and its fractions (except Ca.Aq) produced endothelium-dependent vasorelaxation, which was partially reversed with endothelium removal and by pretreating intact aortic rings with L-NAME (10µM) and atropine (1µM). This relaxation to Ca.Cr and fractions (nHexane, ethylacetate and chloroform) was also eliminated with indomethacin pretreatment, however, it unmasked a vasoconstriction effect with Ca.Cr only. Surprisingly, the aqueous fraction produced a calcium sensitive strong vasoconstriction instead of vasorelaxation. The crude extract and its fractions (except Ca.Aq) also antagonized vasoconstriction induced with high K+ (80mM), suggesting calcium antagonistic effect. The aqueous fraction produced mild vasorelaxation against high K+. This effect was further confirmed when pretreatment of the aortic rings with different concentrations of crude extract and fractions suppressed CaCl2 concentration response curves, similar to verapamil. In acute toxicity test, Ca.Cr extract was found safe up to 5g/kg body weight in mice. CONCLUSION: These findings suggest that crude extract and fractions of C. album produced vasorelaxant effect through muscarinic receptors linked-NO pathway, prostaglandin (endothelium-dependent) and calcium antagonism (endothelium-independent), which explains the blood pressure lowering effect of C. album in rats.

Defective TiO2- x for High-Performance Electrocatalytic NO Reduction toward Ambient NH3 Production.

Synthesis of green ammonia (NH3 ) via electrolysis of nitric oxide (NO) is extraordinarily sustainable, but multielectron/proton-involved hydrogenation steps as well as low concentrations of NO can lead to poor activities and selectivities of electrocatalysts. Herein, it is reported that oxygen-defective TiO2 nanoarray supported on Ti plate (TiO2- x /TP) behaves as an efficient catalyst for NO reduction to NH3 . In 0.2 m phosphate-buffered electrolyte, such TiO2- x /TP shows competitive electrocatalytic NH3 synthesis activity with a maximum NH3 yield of 1233.2 µg h-1  cm-2 and Faradaic efficiency of 92.5%. Density functional theory calculations further thermodynamically faster NO deoxygenation and protonation processes on TiO2- x (101) compared to perfect TiO2 (101). And the low energy barrier of 0.7 eV on TiO2- x (101) for the potential-determining step further highlights the greatly improved intrinsic activity. In addition, a Zn-NO battery is fabricated with TiO2- x /TP and Zn plate to obtain an NH3 yield of 241.7 µg h-1  cm-2 while providing a peak power density of 0.84 mW cm-2 .

Partial characterization of purified glycoprotein from nutshell of Arachis hypogea L. towards macrophage activation and leishmaniacidal activity.

Arachis hypogea L. protein fraction-2 (AHP-F2) from the Peanut shell was extracted and characterized and its potent immunomodulatory and anti-leishmanial role was determined in this present study. AHP-F2 was found to be a glycoprotein as the presence of carbohydrates were confirmed by the analysis of high-performance liquid chromatography (HPLC) yielded glucose, galactose, mannose, and xylose. AHP-F2 molecular mass was found to be ∼28 kDa as indicated in MALDI-TOF and peptide mass fingerprinting analysis followed by Mascot search. The peptide matches revealed the similarity of the mannose/glucose binding lectin with 71.07% in the BLAST analysis. After that, the 3D structure of the AHP-F2 model was designed and validated by the Ramachandran plot. The immunomodulatory role of AHP-F2 was established in murine peritoneal macrophages as induction of nitric oxide (NO), and stimulation of proinflammatory cytokines (IL-12 and IFN-γ) in a dose-dependent manner was observed. Interestingly, it was also found that AHP-F2 has interacted with the innate immune receptor, toll-like receptors (TLRs) as established in molecular docking as well as mRNA expression. The anti-leishmanial potential of AHP-F2 was revealed with a prominent inhibition of amastigote growth within the murine macrophages with prompt induction of nitrite release. Altogether, the isolated AHP-F2 from Arachis hypogea L. has strong immunomodulatory and anti-leishmanial potential which may disclose a new path to treat leishmaniasis.

Dimethylarginine Dimethylaminohydrolase - 1 expression is increased under tBHP-induced oxidative stress regulates nitric oxide production in PCa cells attenuates mitochondrial ROS-mediated apoptosis.

Dimethylarginine dimethylaminohydrolase-1 (DDAH1) expression is frequently elevated in different cancers including prostate cancer (PCa) and enhances nitric oxide (NO) production in tumor cells by metabolising endogenous nitric oxide synthase (NOS) inhibitors. DDAH1 protects the PCa cells from cell death and promotes survival. In this study, we have investigated the cytoprotective role of DDAH1 and determined the mechanism of DDAH1 in protecting the cells in tumor microenvironment. Proteomic analysis of PCa cells with stable overexpression of DDAH1 has identified that oxidative stress-related activity is altered. Oxidative stress promotes cancer cell proliferation, survival and causes chemoresistance. A known inducer of oxidative stress, tert-Butyl Hydroperoxide (tBHP) treatment to PCa cells led to elevated DDAH1 level that is actively involved in protecting the PCa cells from oxidative stress induced cell damage. In PC3-DDAH1- cells, tBHP treatment led to higher mROS levels indicating that the loss of DDAH1 increases the oxidative stress and eventually leads to cell death. Under oxidative stress, nuclear Nrf2 controlled by SIRT1 positively regulates DDAH1 expression in PC3 cells. In PC3-DDAH1+ cells, tBHP induced DNA damage is well tolerated compared to wild-type cells while PC3-DDAH1- became sensitive to tBHP. In PC3 cells, tBHPexposure has increased the production of NO and GSH which may be acting as an antioxidant defence to overcome oxidative stress. Furthermore, in tBHP treated PCa cells, DDAH1 is controlling the expression of Bcl2, active PARP and caspase 3. Taken together, these results confirm that DDAH1 is involved in the antioxidant defence system and promotes cell survival.

Effects of extended-release 7-nitroindazole gel formulation treatment on the behavior of Shank3 mouse model of autism.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by behavioral deficits such as abnormalities in communication, social interaction, anxiety, and repetitive behavior. We have recently shown that the Shank3 mutation in mice representing a model of ASD causes excessive nitric oxide (NO) levels and aberrant protein S-nitrosylation. Further, 10-day daily injections of 7-NI, a neuronal nitric oxide synthase inhibitor, into Shank3Δ4-22 and Cntnap2(-/-) mutant mice (models of ASD) at a dose of 80 mg/kg reversed the manifestations of ASD phenotype. In this study, we proposed an extended release of 7-NI using a novel drug system. Importantly, unlike the intraperitoneal injections, our new preparation of poly (sebacic acid-co-ricinoleic acid) (PSARA) gel containing 7-NI was injected subcutaneously into the mutant mice only once. The animals underwent behavioral testing starting from day 3 post-injection. It should be noted that the developed PSARA gel formulation allowed a slow release of 7-NI maintaining the plasma level of the drug at ∼45 µg/ml/day. Further, we observed improved memory and social interaction and reduced anxiety-like behavior in Shank3 mutant mice. This was accompanied by a reduction in 3-nitrotyrosine levels (an indicator of nitrative/nitrosative stress) in plasma. Overall, we suggest that our single-dose formulation of PSARA gel is very efficient in rendering a therapeutic effect of 7-NI for at least 10 days. This approach may provide in the future a rational design of an effective ASD treatment using 7-NI and its clinical translation.

Live to die another day: novel insights may explain the pathophysiology behind smoker's paradox in SARS-CoV-2 infection.

The severe acute respiratory coronavirus 2 (SARS-CoV-2) infection demonstrates a highly variable and unpredictable course. Several reports have claimed a smoker's paradox in coronavirus disease 2019 (COVID-19), in line with previous suggestions that smoking is associated with better survival after acute myocardial infarction and appears protective in preeclampsia. Several plausible physiological explanations exist accounting for the paradoxical observation of smoking engendering protection against SARS-CoV-2 infection. In this review, we delineate novel mechanisms whereby smoking habits and smokers' genetic polymorphism status affecting various nitric oxide (NO) pathways (endothelial NO synthase, cytochrome P450 (CYP450), erythropoietin receptor (EPOR); ß-common receptor (ßcR)), along with tobacco smoke modulation of microRNA-155 and aryl-hydrocarbon receptor (AHR) effects, may be important determinators of SARS-CoV-2 infection and COVID-19 course. While transient NO bioavailability increase and beneficial immunoregulatory modulations through the above-mentioned pathways using exogenous, endogenous, genetic and/or therapeutic modalities may have direct and specific, viricidal SARS-CoV-2 effects, employing tobacco smoke inhalation to achieve protection equals self-harm. Tobacco smoking remains the leading cause of death, illness, and impoverishment.