Nitric Oxide Donors as Potential Drugs for the Treatment of Vascular Diseases Due to Endothelium Dysfunction

NONO2P, a nitric oxide donor, induces relaxation in coronary artery, negative inotropism and hypotensive effect in rats

Reduced NO synthesis and/or bioavailability is related with many cardiovascular diseases, such as coronary artery disease and hypertension. This study aimed to evaluate the effects of cis-[Ru(NO)(NO2)(phen)2](PF6)2-(NONO2P) on blood pressure in normotensive and hypertensive rats. Specifically, we wanted to investigate its action on the atrial contractility, mesenteric and coronary arteries function. Male Wistar and spontaneously hypertensive rats (SHR) (13-18 weeks old) were used to assess the NONO2P effects on blood pressure and heart rate. Superior mesenteric and coronary arteries, and atria were isolated for recording to analyze force changes. Cultured endothelial cells were used to measure intracellular reactive oxygen species (ROS) generation using fluorescent dye (dihydroethidium, DHE). Acute administration of NONO2P induced hypotension in non-anesthetized normotensive and hypertensive rats. Moreover, NONO2P caused a negative inotropic effect without altering cardiac rhythmicity. Further, NONO2P displays a vasorelaxant effect on different blood vessels (mesenteric and coronary arteries). For comparison purposes, we observed that NONO2P and NTG presented with a similar potency and maximum response values in inducing relaxation in coronary arteries. On the other hand, mesenteric arteries were more sensitive to both donors, NONO2P and NTG, than the coronary artery. In addition, exposure to NONO2P induced tolerance and increased ROS levels. This is the first evidence that NONO2P induces hypotension, negative cardiac inotropism and coronary artery relaxation. In addition, pre-exposure to NONO2P induces vascular tolerance. Overall, these results may shed light on the potential therapeutic use of NONO2P, particularly in treating angina and hypertensive crises.

Treatment of endothelial cell dysfunction in atherosclerosis: a new perspective integrating traditional and modern approaches

Atherosclerosis (AS), a prime causative factor in cardiovascular disease, originates from endothelial cell dysfunction (ECD). Comprising a vital part of the vascular endothelium, endothelial cells play a crucial role in maintaining vascular homeostasis, optimizing redox balance, and regulating inflammatory responses. More evidence shows that ECD not only serves as an early harbinger of AS but also exhibits a strong association with disease progression. In recent years, the treatment strategies for ECD have been continuously evolving, encompassing interventions ranging from lifestyle modifications to traditional pharmacotherapy aimed at reducing risk factors, which also have demonstrated the ability to improve endothelial cell function. Additionally, novel strategies such as promising biotherapy and gene therapy have drawn attention. These methods have demonstrated enormous potential and promising prospects in improving endothelial function and reversing AS. However, it is essential to remain cognizant that the current treatments still present significant challenges regarding therapeutic efficacy, long-term safety, and ethical issues. This article aims to provide a systematic review of these treatment methods, analyze the mechanisms and efficacy of various therapeutic strategies, with the goal of offering insights and guidance for clinical practice, and further advancing the prevention and treatment of cardiovascular diseases.

A comprehensive review on the plant sources, pharmacological activities and pharmacokinetic characteristics of Syringaresinol

Syringaresinol, a phytochemical constituent belonging to lignan, is formed from two sinapyl alcohol units linked via a β-β linkage, which can be found in a wide variety of cereals and medicinal plants. Medical researches revealed that Syringaresinol possesses a broad spectrum of biological activities, including anti-inflammatory, anti-oxidation, anticancer, antibacterial, antiviral, neuroprotection, and vasodilation effects. These pharmacological properties lay the foundation for its use in treating various diseases such as inflammatory diseases, neurodegenerative disorders, diabetes and its complication, skin disorders, cancer, cardiovascular, and cerebrovascular diseases. As the demand for natural therapeutics increases, Syringaresinol has garnered significant attention for its pharmacological properties. Despite the extensive literature that highlights the various biological activities of this molecule, the underlying mechanisms and the interrelationships between these activities are rarely addressed from a comprehensive perspective. Moreover, no thorough comprehensive summary and evaluation of Syringaresinol has been conducted to offer recommendations for potential future clinical trials and therapeutic applications of this bioactive compound. Thus, a comprehensive review on Syringaresinol is essential to advance scientific understanding, assess its therapeutic applications, ensure safety, and guide future research efforts. This will ultimately contribute to its potential integration into clinical practice and public health. This study aims to provide a comprehensive overview of Syringaresinol on its sources and biological activities to provide insights into its therapeutic potential, and to provide a basis for high-quality studies to determine the clinical efficacy of this compound. Additionally, we explored the pharmacokinetics, toxicology, and drug development aspects of Syringaresinol to guide future research efforts. The review also discussed the limitations of current research on Syringaresinol and put forward some new perspectives and challenges, which laid a solid foundation for further study on clinical application and new drug development of Syringaresinol in the future.

Nanoparticle-Based Nitric Oxide Donors: Exploring Their Antimicrobial and Anti-Biofilm Capabilities

Background: Nitric oxide (NO) is an antimicrobial and anti-biofilm agent with significant potential for combating biofilm-associated infections and antibiotic resistance. However, owing to its high reactivity due to the possession of a free radical and short half-life (1-5 s), the practical application of NO in clinical settings is challenging. Objectives: This review explores the development of NO-releasing nanoparticles that provide a controlled, targeted delivery system for NO, enhancing its antimicrobial efficacy while minimizing toxicity. The review discusses various NO donors, nanoparticle platforms, and how NO disrupts biofilm formation and eradicates pathogens. Additionally, we examine the highly encouraging and inspiring results of NO-releasing nanoparticles against multidrug-resistant strains and their applications in medical and environmental contexts. This review highlights the promising role of NO-based nanotechnologies in overcoming the challenges posed by increasing antibiotic resistance and biofilm-associated infections. Conclusions: Although NO donors and nanoparticle delivery systems show great potential for antimicrobial and anti-biofilm uses, addressing challenges related to controlled release, toxicity, biofilm penetration, resistance, and clinical application is crucial.

The vascular influence of melatonin on endothelial response to angiotensin II in diabetic rat aorta

The current study explored melatonin (MEL) and its receptors, including MEL type 1 receptor (MT1) receptor and MEL type 2 receptor (MT2), along with the angiotensin-converting enzyme 2 (ACE2), influence on vascular responses to angiotensin II (Ang II) in rat aortic segments of normal and diabetic rats. The isolated aortic segments were exposed to MEL, the MEL agonist; ramelteon (RAM), the MEL antagonist; luzindole (LUZ), and an ACE2 inhibitor (S, S)-2-(1-Carboxy-2-(3-(3,5-dichlorobenzyl)-3 H-imidazol-4-yl)-ethylamino)-4-methylpentanoic acid,) on Ang II-induced contractions in non-diabetic normal endothelium (non-DM E+), non-diabetic removed endothelium (non-DM E-), and streptozotocin-induced diabetic endothelium-intact (STZ-induced DM E+) rat aortic segments, as well as their combination in STZ-induced DM E + segments, were also included. The current results showed that MEL and RAM shifted Ang II dose-response curve (DRC) to the right side in non-DM E + and non-DM E- aorta but not in STZ-induced DM E + aorta. However, ACE2 inhibition abolished Ang II degradation only in STZ-induced DM E + segments, not in non-DM E + segments. Additionally, the combinations of MEL-LUZ and RAM-ACE2 inhibitor caused a rightward shift in Ang II response in STZ-induced DM E + segments, while the MEL-LUZ combination decreased Ang II DRC. The findings suggest that the effects of MEL and ACE2 inhibitor on Ang II responses depend on the condition of the endothelium and the distribution of the MEL receptors.

NONO2P, a novel nitric oxide donor, causes vasorelaxation through NO/sGC/PKG pathway, K+ channels opening and SERCA activation

BACKGROUND & AIMS

The treatment of cardiovascular diseases (CVD) could greatly benefit from using nitric oxide (NO) donors. This study aimed to investigate the mechanisms of action of NONO2P that contribute to the observed responses in the mesenteric artery. The hypothesis was that NONO2P would have similar pharmacological actions to sodium nitroprusside (SNP) and NO.

METHODS

Male Wistar rats were euthanized to isolate the superior mesenteric artery for isometric tension recordings. NO levels were measured using the DAF-FM/DA dye, and cyclic guanosine monophosphate (cGMP) levels were determined using a cGMP-ELISA Kit.

RESULTS

NONO2P presented a similar maximum efficacy to SNP. The free radical of NO (NO•) scavengers (PTIO; 100 μM and hydroxocobalamin; 30 μM) and nitroxyl anion (NO-) scavenger (L-cysteine; 3 mM) decreased relaxations promoted by NONO2P. The presence of the specific soluble guanylyl cyclase (sGC) inhibitor (ODQ; 10 μM) nearly abolished the vasorelaxation. The cGMP-dependent protein kinase (PKG) inhibition (KT5823; 1 μM) attenuated the NONO2P relaxant effect. The vasorelaxant response was significantly attenuated by blocking inward rectifying K+ channels (Kir), voltage-operated K+ channels (KV), and large conductance Ca2+-activated K+ channels (BKCa). NONO2P-induced relaxation was attenuated by cyclopiazonic acid (10 μM), indicating that sarcoplasmic reticulum Ca2+-ATPase (SERCA) activation is involved in this relaxation. Moreover, NONO2P increased NO levels in endothelial cells and cGMP production.

CONCLUSIONS

NONO2P induces vasorelaxation with the same magnitude as SNP, releasing NO• and NO-. Its vasorelaxant effect involves sGC, PKG, K+ channels opening, and SERCA activation, suggesting its potential as a therapeutic option for CVD.

Mitochondrial dysfunction in the pathogenesis of endothelial dysfunction

Cardiovascular diseases (CVDs) are a matter of concern worldwide, and mitochondrial dysfunction is one of the major contributing factors. Vascular endothelial dysfunction has a major role in the development of atherosclerosis because of the abnormal chemokine secretion, inflammatory mediators, enhancement of LDL oxidation, cytokine elevation, and smooth muscle cell proliferation. Endothelial cells transfer oxygen from the pulmonary circulatory system to the tissue surrounding the blood vessels, and a majority of oxygen is transferred to the myocardium by endothelial cells, which utilise a small amount of oxygen to generate ATP. Free radicals of oxide are produced by mitochondria, which are responsible for cellular oxygen uptake. Increased mitochondrial ROS generation and reduction in agonist-stimulated eNOS activation and nitric oxide bioavailability were directly linked to the observed change in mitochondrial dynamics, resulting in various CVDs and endothelial dysfunction. Presently, the manuscript mainly focuses on endothelial dysfunction, providing a deep understanding of the various features of mitochondrial mechanisms that are used to modulate endothelial dysfunction. We talk about recent findings and approaches that may make it possible to detect mitochondrial dysfunction as a potential biomarker for risk assessment and diagnosis of endothelial dysfunction. In the end, we cover several targets that may reduce mitochondrial dysfunction through both direct and indirect processes and assess the impact of several different classes of drugs in the context of endothelial dysfunction.

The relationship of redox signaling with the risk for atherosclerosis

Oxidative balance plays a pivotal role in physiological homeostasis, and many diseases, particularly age-related conditions, are closely associated with oxidative imbalance. While the strategic role of oxidative regulation in various diseases is well-established, the specific involvement of oxidative stress in atherosclerosis remains elusive. Atherosclerosis is a chronic inflammatory disorder characterized by plaque formation within the arteries. Alterations in the oxidative status of vascular tissues are linked to the onset, progression, and outcome of atherosclerosis. This review examines the role of redox signaling in atherosclerosis, including its impact on risk factors such as dyslipidemia, hyperglycemia, inflammation, and unhealthy lifestyle, along with dysregulation, vascular homeostasis, immune system interaction, and therapeutic considerations. Understanding redox signal transduction and the regulation of redox signaling will offer valuable insights into the pathogenesis of atherosclerosis and guide the development of novel therapeutic strategies.

The Significance of Genetically Determined Methylation and Folate Metabolism Disorders in the Pathogenesis of Coronary Artery Disease: A Target for New Therapies?

Methylation is a biochemical process involving the addition of a methyl group (-CH3) to various chemical compounds. It plays a crucial role in maintaining the homeostasis of the endothelium, which lines the interior surface of blood vessels, and has been linked, among other conditions, to coronary artery disease (CAD). Despite significant progress in CAD diagnosis and treatment, intensive research continues into genotypic and phenotypic CAD biomarkers. This review explores the significance of the methylation pathway and folate metabolism in CAD pathogenesis, with a focus on endothelial dysfunction resulting from deficiency in the active form of folate (5-MTHF). We discuss emerging areas of research into CAD biomarkers and factors influencing the methylation process. By highlighting genetically determined methylation disorders, particularly the MTHFR polymorphism, we propose the potential use of the active form of folate (5-MTHF) as a novel CAD biomarker and personalized pharmaceutical for selected patient groups. Our aim is to improve the identification of individuals at high risk of CAD and enhance their prognosis.

Modulating Nitric Oxide: Implications for Cytotoxicity and Cytoprotection

Despite the significant progress in the fields of biology, physiology, molecular medicine, and pharmacology; the designation of the properties of nitrogen monoxide in the regulation of life-supporting functions of the organism; and numerous works devoted to this molecule, there are still many open questions in this field. It is widely accepted that nitric oxide (•NO) is a unique molecule that, despite its extremely simple structure, has a wide range of functions in the body, including the cardiovascular system, the central nervous system (CNS), reproduction, the endocrine system, respiration, digestion, etc. Here, we systematize the properties of •NO, contributing in conditions of physiological norms, as well as in various pathological processes, to the mechanisms of cytoprotection and cytodestruction. Current experimental and clinical studies are contradictory in describing the role of •NO in the pathogenesis of many diseases of the cardiovascular system and CNS. We describe the mechanisms of cytoprotective action of •NO associated with the regulation of the expression of antiapoptotic and chaperone proteins and the regulation of mitochondrial function. The most prominent mechanisms of cytodestruction-the initiation of nitrosative and oxidative stresses, the production of reactive oxygen and nitrogen species, and participation in apoptosis and mitosis. The role of •NO in the formation of endothelial and mitochondrial dysfunction is also considered. Moreover, we focus on the various ways of pharmacological modulation in the nitroxidergic system that allow for a decrease in the cytodestructive mechanisms of •NO and increase cytoprotective ones.

Dietary nitrate supplementation to enhance exercise capacity in patients with COPD: Evidence from a meta-analysis of randomized controlled trials and a network pharmacological analysis

OBJECTIVE

The potential effects of nitrate in patients with chronic obstructive pulmonary disease (COPD) have attracted increased research interest. However, previous clinical trials have reported inconsistent results, and consecutive meta-analyses have failed to reach a consensus. Since some randomized controlled trials have recently been conducted that can provide more evidence, we performed an updated meta-analysis.

METHODS

A comprehensive literature search was conducted using PubMed, the Cochrane Library, Embase, and Web of Science databases to identify trials that assessed the efficacy and safety of nitrate in patients with COPD. The Revman 5.3 software was used for data analysis. Mean difference (MD) or standardized mean difference (SMD) with 95 % confidence interval (CI) was used as the effect measure, and forest plots were used to display individual and pooled results. Network pharmacology analysis was conducted to investigate the potential mechanisms of nitrate action in COPD.

RESULTS

Eleven studies involving 287 patients were included in this meta-analysis. The results indicated that dietary nitrate supplementation increased plasma nitrate and nitrite concentrations and fractional exhaled nitric oxide in patients with COPD. Nitrate improved exercise capacity [SMD = 0.38, 95 % CI = 0.04-0.72] and endothelial function [MD = 9.41, 95 % CI = 5.30-13.52], and relieved dyspnea in patients with COPD. Network pharmacology identified AKT1, IL1B, MAPK3, and CASP3 as key treatment targets.

CONCLUSION

Dietary nitrate supplementation could be used as a potential treatment for patients with COPD, especially to increase their exercise capacity. The underlying mechanisms may be related to AKT1, IL1B, MAPK3, and CASP3.

The roles of angiotensin-converting enzyme 2 inhibitor, melatonin and its agonist on angiotensin II reactivity in intact and denuded rat aortic rings

BACKGROUND

The pineal product melatonin (MEL) modulates blood vessels through G protein-coupled receptors (GPCRs) called melatonin type 1 receptor (MT1R) and melatonin type 2 receptor (MT2R), in that order. The renin-angiotensin system (RAS), which breaks down angiotensin II (Ang II) to create Ang 1-7, is thought to be mostly controlled by angiotensin-converting enzyme-2 (ACE2).

AIM

The current work examines the involvement of ACE2 inhibitor, MEL, and ramelteon (RAM) in the vascular response to Ang II activities in the endothelial denuded (E-) and intact (E+) rat isolated thoracic aortic rings.

METHOD

The isometric tension was measured to evaluate the vascular Ang II contractility using dose response curve (DRC).

RESULTS

MEL and RAM caused a rightward shift of Ang II in endothelium E + and endothelium E- aorta.

CONCLUSION

According to the current study, the distribution of MEL receptors and the endothelium's condition are related to the vasomodulatory effect of MEL and ACE2 on Ang II attenuation. These physiological interactions can control vascular tone and increase Ang II reactivity denude endothelial layaer.

Chemical composition, antioxidant, and enzyme inhibitory properties of Rauwolfia vomitoria extract

OBJECTIVES

Rauwolfia vomitoria is one ethno-botanicals in Nigeria used by traditional health practitioners in managing several human diseases. However, necessary information regarding its effect on enzymes implicated in the development and progression of erectile dysfunction is missing in the literature. Thus, this study investigated the antioxidant property and impact of Rauwolfia vomitoria extract on erectile dysfunction-related enzymes in vitro.

METHODS

High performance liquid chromatography was used to identify and quantify Rauwolfia vomitoria's phenolic components. Then, utilizing common antioxidant assays, the extract's antioxidant properties were evaluated and finally the effect of the extract on some enzymes (AChE, arginase and ACE) implicated in erectile dysfunction was investigated in vitro.

RESULTS

The results showed that the extract inhibited AChE (IC50=388.72 μg/mL), arginase (IC50=40.06 μg/mL) and ACE (IC50=108.64 μg/mL) activities. In addition, phenolic rich extract of Rauvolfia vomitoria scavenged radicals and chelated Fe2+ in concentration dependent manner. Furthermore, rutin, chlorogenic acid, gallic acid, and kaempferol were found in large quantities by HPLC analysis.

CONCLUSIONS

Therefore, one of the potential reasons driving Rauwolfia vomitoria's use in folk medicine for the treatment of erectile dysfunction could be its antioxidant and inhibitory activities on several enzymes linked to erectile dysfunction in vitro.

Nitric Oxide Synthases in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease characterized by severe joint damage and disability. However, the specific mechanism of RA has not been thoroughly clarified over the past decade. Nitric oxide (NO), a kind of gas messenger molecule with many molecular targets, is demonstrated to have significant roles in histopathology and homeostasis. Three nitric oxide synthases (NOS) are related to producing NO and regulating the generation of NO. Based on the latest studies, NOS/NO signaling pathways play a key role in the pathogenesis of RA. Overproduction of NO can induce the generation and release of inflammatory cytokines and act as free radical gas to accumulate and trigger oxidative stress, which can involve in the pathogenesis of RA. Therefore, targeting NOS and its upstream and downstream signaling pathways may be an effective approach to managing RA. This review clearly summarizes the NOS/NO signaling pathway, the pathological changes of RA, the involvement of NOS/NO in RA pathogenesis and the conventional and novel drugs based on NOS/NO signaling pathways that are still in clinical trials and have good therapeutic potential in recent years, with an aim to provide a theoretical basis for further exploration of the role of NOS/NO in the pathogenesis, prevention and treatment of RA.

Inflammation of the Human Dental Pulp Induces Phosphorylation of eNOS at Thr495 in Blood Vessels

The activity of endothelial nitric oxide synthase (eNOS) in endothelial cells increased with the phosphorylation of the enzyme at Ser1177 and decreased at Thr495. The regulation of the phosphorylation sites of eNOS at Ser1177 and Thr495 in blood vessels of the healthy and inflamed human dental pulp is unknown. To investigate this, healthy and carious human third molars were immersion-fixed and decalcified. The localization of eNOS, Ser1177, and Thr495 in healthy and inflamed blood vessels was examined in consecutive cryo-sections using quantitative immunohistochemical methods. We found that the staining intensity of Ser1177 in healthy blood vessels decreased in inflamed blood vessels, whereas the weak staining intensity of Thr495 in healthy blood vessels strongly increased in inflamed blood vessels. In blood vessels of the healthy pulp, eNOS is active with phosphorylation of the enzyme at Ser1177. The phosphorylation of eNOS at Thr495 in inflamed blood vessels leads to a decrease in eNOS activity, contributing to eNOS uncoupling and giving evidence for a decrease in NO and an increase in O2− production. Since the formation of the tertiary dentin matrix depends on intact pulp circulation, eNOS uncoupling and phosphorylation of eNOS at Thr495 in the inflamed pulp blood vessels should be considered during caries therapy.

Synergistic anti-inflammatory effects and mechanisms of the combination of resveratrol and curcumin in human vascular endothelial cells and rodent aorta

Chronic increased pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α) play critical roles in the development of endothelial dysfunction and therefore induce cardiovascular disease. Although phytochemicals have the potential ability to reduce the risk of CVD, the big gap between required high concentration in cells and the low bioavailability in the blood of phytochemicals compromise their therapeutic potentials. This study aims to investigate if combined phytochemicals at low levels exert a synergistic anti-inflammatory effect and to define relevant molecular mechanisms. Our results found that combined curcumin (5 µM) and resveratrol (5 µM) synergistically (combination index is 0.78) inhibited TNF-α-induced monocytes adhesion to human endothelial EA.hy 926 cells while the individual chemicals did not have such effect at the selected concentrations. The concentrations of curcumin (5 µM) and resveratrol (5 µM) are very close to the maximum level of curcumin (3.56 µM) and resveratrol (2 µM) in human blood. Dietary supplementation of combined curcumin (500mg/kg) and resveratrol (200mg/kg) synergistically reduced TNF-α-induced vascular inflammation in C57BL/6 mice with a similar pattern in cells. Moreover, the combination ameliorated the TNF-α-induced protein expressions and circulating levels of vascular cell adhesion molecule 1 and monocyte chemotactic protein-1 in EA.hy 926 cells, mice aorta and serum. Furthermore, combined curcumin and resveratrol significantly inhibited TNF-α-induced nuclear factor-kappaB (NF-κB) p65 nuclear protein expression than that by the individual chemical alone in EA.hy 926 cells, indicating that the synergistic effect of the combination may result from that curcumin reduces the required minimum concentration for resveratrol to inhibit the nuclear translocation of NF-κB. In conclusion, the combination of curcumin and resveratrol protects against TNF-α-induced vascular inflammation by suppressing NF-κB signaling in vitro and in vivo models. This study suggests that dietary intake of a combination of curcumin and resveratrol or its foods may be a practical, safe approach to prevent vascular inflammation and therefore prevent/treat vascular diseases in humans.

The Contribution of Gut Microbiota and Endothelial Dysfunction in the Development of Arterial Hypertension in Animal Models and in Humans

The maintenance of the physiological values of blood pressure is closely related to unchangeable factors (genetic predisposition or pathological alterations) but also to modifiable factors (dietary fat and salt, sedentary lifestyle, overweight, inappropriate combinations of drugs, alcohol abuse, smoking and use of psychogenic substances). Hypertension is usually characterized by the presence of a chronic increase in systemic blood pressure above the threshold value and is an important risk factor for cardiovascular disease, including myocardial infarction, stroke, micro- and macro-vascular diseases. Hypertension is closely related to functional changes in the endothelium, such as an altered production of vasoconstrictive and vasodilator substances, which lead to an increase in vascular resistance. These alterations make the endothelial tissue unresponsive to autocrine and paracrine stimuli, initially determining an adaptive response, which over time lead to an increase in risk or disease. The gut microbiota is composed of a highly diverse bacterial population of approximately 10¹⁴ bacteria. A balanced intestinal microbiota preserves the digestive and absorbent functions of the intestine, protecting from pathogens and toxic metabolites in the circulation and reducing the onset of various diseases. The gut microbiota has been shown to produce unique metabolites potentially important in the generation of hypertension and endothelial dysfunction. This review highlights the close connection between hypertension, endothelial dysfunction and gut microbiota.

Cardiovascular characterization of the novel organic mononitrate NDIBP in rats

Organic nitrates are widely used to restore endogenous nitric oxide (NO) levels reduced by endothelial nitric oxide synthase dysfunction. However, these drugs are associated with undesirable side effects, including tolerance. This study aims to investigate the cardiovascular effects of the new organic nitrate 1,3-diisobutoxypropan-2-yl nitrate (NDIBP). Specifically, we assessed its effects on blood pressure, vascular reactivity, acute toxicity, and the ability to induce tolerance. In vitro and ex vivo techniques showed that NDIBP released NO both in a cell-free system and in isolated mesenteric arteries preparations through a process catalyzed by xanthine oxidoreductase. NDIBP also evoked endothelium-independent vasorelaxation, which was significantly attenuated by 2-phenyl-4,4,5,5,-tetramethylimidazoline-1-oxyl 3-oxide (PTIO, 300 μM), a nitric oxide scavenger; 1-H-[1,2,4] oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ, 10 μM), a soluble guanylyl cyclase inhibitor; tetraethylammonium (TEA, 3 mM), a potassium channel blocker; febuxostat (500 nM), a xanthine oxidase inhibitor; and proadifen (10 μM), an inhibitor of cytochrome P450 enzyme. Furthermore, this organic nitrate did not induce tolerance in isolated vessels and presented low toxicity following acute oral administration. In vivo changes on cardiovascular parameters were assessed using normotensive and renovascular hypertensive rats. NDIBP evoked a reduction of blood pressure that was significantly higher in hypertensive animals. Our results suggest that NDIBP acts as a NO donor, inducing blood pressure reduction without having the undesirable effects of tolerance. Those effects seem to be mediated by activation of NO-sGC-cGMP pathway and positive modulation of K+ channels in vascular smooth muscle.

Enhanced Oral NO Delivery through Bioinorganic Engineering of Acid-Sensitive Prodrug into a Transformer-like DNIC@MOF Microrod

Nitric oxide (NO) is an endogenous gasotransmitter regulating alternative physiological processes in the cardiovascular system. To achieve translational application of NO, continued efforts are made on the development of orally active NO prodrugs for long-term treatment of chronic cardiovascular diseases. Herein, immobilization of NO-delivery [Fe₂(μ-SCH₂CH₂COOH)₂(NO)₄] (DNIC-2) onto MIL-88B, a metal-organic framework (MOF) consisting of biocompatible Fe³⁺ and 1,4-benzenedicarboxylate (BDC), was performed to prepare a DNIC@MOF microrod for enhanced oral delivery of NO. In simulated gastric fluid, protonation of the BDC linker in DNIC@MOF initiates its transformation into a DNIC@tMOF microrod, which consisted of DNIC-2 well dispersed and confined within the BDC-based framework. Moreover, subsequent deprotonation of the BDC-based framework in DNIC@tMOF under simulated intestinal conditions promotes the release of DNIC-2 and NO. Of importance, this discovery of transformer-like DNIC@MOF provides a parallel insight into its stepwise transformation into DNIC@tMOF in the stomach followed by subsequent conversion into molecular DNIC-2 in the small intestine and release of NO in the bloodstream of mice. In comparison with acid-sensitive DNIC-2, oral administration of DNIC@MOF results in a 2.2-fold increase in the oral bioavailability of NO to 65.7% in mice and an effective reduction of systolic blood pressure (SBP) to a ΔSBP of 60.9 ± 4.7 mmHg in spontaneously hypertensive rats for 12 h.

Lack of TRPV1 aggravates obesity-associated hypertension through the disturbance of mitochondrial Ca2+ homeostasis in brown adipose tissue

The combination of obesity and hypertension is associated with high morbidity and mortality; however, the mechanism underlying obesity-induced hypertension remains unclear. In this study, we detected the possible effects of TRPV1, a previously identified antihypertensive calcium (Ca²⁺) channel in adipose tissue, on the occurrence of obesity and hypertension in mice lacking UCP1, a spontaneously genetically manipulated obesity model, by generating TRPV1 and UCP1 double knockout mice. In these mice, obesity and hypertension appeared earlier and were more severe than in mice with the knockout of UCP1 or TRPV1 alone. The knockout of TRPV1 in UCP1 knockout mice further reduced functional brown adipose tissue (BAT) generation; decreased resting oxygen consumption, heat production, and locomotor activities; and was accompanied by severe mitochondrial respiratory dysfunction in BAT. Mechanistically, TRPV1, UCP1, and LETM1 acted as a complex to maintain an appropriate mitochondrial Ca²⁺ level, and TRPV1 knockout caused a compensatory increase in mitochondrial Ca²⁺ uptake via LETM1 activation. However, the compensatory response was blocked in UCP1^−/− mice, resulting in dramatically reduced mitochondrial Ca²⁺ uptake and higher production of ATP and oxidative stress. This study provides in vivo evidence for the critical role of BAT mitochondrial Ca²⁺ homeostasis in obesity-associated hypertension and indicates that the TRPV1/UCP1/LETM1 complex may be an alternative intervention target.

A novel triruthenium nitrosyl bearing a quinolinic ligand: a comparison of its spectroscopic behavior with its pyridine analogues

A comparative analysis of ruthenium nitrosyl spectroscopic data helps unravel the electronic character of the unit {RuNO}6[RuIIIRuIIIO].

Fenofibrate Prevents nicotine-induced Acute Kidney Injury: Possible Involvement of Endothelial Nitric Oxide Synthase

Objective:

The present study investigated the possible effect of fenofibrate (peroxisome proliferator-activated receptors-α agonist) in nicotine-induced acute kidney injury (AKI) in rats.

Materials and Methods:

Nicotine (2 mg/kg/day, intraperitoneally) was administered for 4 weeks to induce AKI in rats. Lipid profile and renal oxidative stress were measured and expression of mRNA for eNOS was assessed using reverse transcription-polymerase chain reaction along with serum and renal tissue nitrite levels. Serum creatinine, blood urea nitrogen and microproteinuria were estimated along with the kidney histology, as markers of kidney function. Treatment with fenofibrate (30 mg/kg per oral, 4 weeks) was initiated 3 days before the administration of nicotine and continued for 4 weeks from the day of administration of nicotine.

Results:

Nicotine administered rats developed apparent AKI confirmed by elevated markers of kidney function and noticeable glomerulosclerosis and tubular cell degeneration. Nicotine decreases the expression of mRNA for eNOS, along with serum and renal tissue nitrite levels. In addition, nicotine showed significantly lipid alteration beside decrease oxidative stress, assessed in terms of increase in serum thiobarbituric acid reactive substance and a marked decrease in tissue reduced glutathione. However, fenofibrate significantly prevented the development of nicotine-AKI by reducing serum creatinine, BUN, and urinary protein, normalizing the lipid profile, reducing renal oxidative stress, increases the eNOS expression and concentration of serum and renal nitrate levels.

Conclusion:

Fenofibrate attenuates nicotine-induced AKI, via its antihyperlipidemic and antioxidant property. Moreover, fenofibrate induced upregulation of eNOS expression additionally play key roles in the improvement of nicotine-induced AKI could be the future alternative.

Recent Advances in the Synthesis and Biomedical Applications of Heterocyclic NO-Donors

Nitric oxide (NO) is a key signaling molecule that acts in various physiological processes such as cellular metabolism, vasodilation and transmission of nerve impulses. A wide number of vascular diseases as well as various immune and neurodegenerative disorders were found to be directly associated with a disruption of NO production in living organisms. These issues justify a constant search of novel NO-donors with improved pharmacokinetic profiles and prolonged action. In a series of known structural classes capable of NO release, heterocyclic NO-donors are of special importance due to their increased hydrolytic stability and low toxicity. It is no wonder that synthetic and biochemical investigations of heterocyclic NO-donors have emerged significantly in recent years. In this review, we summarized recent advances in the synthesis, reactivity and biomedical applications of promising heterocyclic NO-donors (furoxans, sydnone imines, pyridazine dioxides, azasydnones). The synthetic potential of each heterocyclic system along with biochemical mechanisms of action are emphasized.

The Role of the BH4 Cofactor in Nitric Oxide Synthase Activity and Cancer Progression: Two Sides of the Same Coin

Cancer development is associated with abnormal proliferation, genetic instability, cell death resistance, metabolic reprogramming, immunity evasion, and metastasis. These alterations are triggered by genetic and epigenetic alterations in genes that control cell homeostasis. Increased reactive oxygen and nitrogen species (ROS, RNS) induced by different enzymes and reactions with distinct molecules contribute to malignant transformation and tumor progression by modifying DNA, proteins, and lipids, altering their activities. Nitric oxide synthase plays a central role in oncogenic signaling modulation and redox landscape. Overexpression of the three NOS isoforms has been found in innumerous types of cancer contributing to tumor growth and development. Although the main function of NOS is the production of nitric oxide (NO), it can be a source of ROS in some pathological conditions. Decreased tetrahydrobiopterin (BH4) cofactor availability is involved in NOS dysfunction, leading to ROS production and reduced levels of NO. The regulation of NOSs by BH4 in cancer is controversial since BH4 has been reported as a pro-tumoral or an antitumoral molecule. Therefore, in this review, the role of BH4 in the control of NOS activity and its involvement in the capabilities acquired along tumor progression of different cancers was described.

Gasotransmitters for the Therapeutic Prevention of Hypertension and Kidney Disease

Nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H₂S), three major gasotransmitters, are involved in pleiotropic biofunctions. Research on their roles in hypertension and kidney disease has greatly expanded recently. The developing kidney can be programmed by various adverse in utero conditions by so-called renal programming, giving rise to hypertension and kidney disease in adulthood. Accordingly, early gasotransmitter-based interventions may have therapeutic potential to revoke programming processes, subsequently preventing hypertension and kidney disease of developmental origins. In this review, we describe the current knowledge of NO, CO, and H₂S implicated in pregnancy, including in physiological and pathophysiological processes, highlighting their key roles in hypertension and kidney disease. We summarize current evidence of gasotransmitter-based interventions for prevention of hypertension and kidney disease in animal models. Continued study is required to assess the interplay among the gasotransmitters NO, CO, and H₂S and renal programming, as well as a greater focus on further clinical translation.

Gasotransmitter signaling in energy homeostasis and metabolic disorders

Gasotransmitters are small molecules of gases, including nitric oxide (NO), hydrogen sulfide (H₂S), and carbon monoxide (CO). These three gasotransmitters can be endogenously produced and regulate a wide range of pathophysiological processes by interacting with specific targets upon diffusion in the biological media. By redox and epigenetic regulation of various physiological functions, NO, H₂S, and CO are critical for the maintenance of intracellular energy homeostasis. Accumulated evidence has shown that these three gasotransmitters control ATP generation, mitochondrial biogenesis, glucose metabolism, insulin sensitivity, lipid metabolism, and thermogenesis, etc. Abnormal generation and metabolism of NO, H₂S, and/or CO are involved in various abnormal metabolic diseases, including obesity, diabetes, and dyslipidemia. In this review, we summarized the roles of NO, H₂S, and CO in the regulation of energy homeostasis as well as their involvements in the metabolism of dysfunction-related diseases. Understanding the interaction among these gasotransmitters and their specific molecular targets are very important for therapeutic applications.