The new organic nitrate 2-nitrate-1,3-diocthanoxypropan (NDOP) induces nitric oxide production and vasorelaxation via activation of inward-rectifier potassium channels (KIR)

Latest Evidence and Perspectives of Panax Notoginseng Extracts and Preparations for the Treatment of Cardiovascular Diseases

ABSTRACT

Cardiovascular diseases are a major cause of death worldwide, and their high incidence poses a significant threat to human health and public health systems. Panax notoginseng , a traditional Chinese medicinal herb with a long history, has shown promise in treating cardiovascular diseases. This review examines the diverse mechanisms through which Panax notoginseng addresses cardiovascular diseases, including anti-inflammatory, antiplatelet aggregation, anticoagulation, anti-oxidative stress, regulation of angiogenesis, antiatherosclerosis, improvement of microcirculatory disorders, and protection against myocardial ischemia-reperfusion injury, highlighting saponins as the principal active components. It also summarizes studies involving Panax notoginseng preparations like Xueshuantong and Xuesaitong in treating coronary heart disease and myocardial infarction, and discusses the safety, limitations, and future research directions of these extracts. In conclusion, the cardiovascular protective mechanism of Panax notoginseng is multitargeted and multipathways, and its clinical application is relatively safe, with rare and mild adverse drug reactions, suggesting a promising therapeutic potential.

Interplay of potassium channel, gastric parietal cell and proton pump in gastrointestinal physiology, pathology and pharmacology

Gastric acid secretion plays a pivotal role in the physiology of gastrointestinal tract. The functioning of the system encompasses a P2 ATPase pump (which shuttles electroneutral function at low pH) along with different voltage sensitive/neutral ion channels, cytosolic proteins, acid sensor receptors as well hormonal regulators. The increased acid secretion is a pathological marker of several diseases like peptic ulcer, gastroesophageal reflux disease (GERD), chronic gastritis, and the bug Helicobacter pylori (H. pylori) has also a critical role, which altogether affects the patient's quality of life. This review comprehensively described the nature of potassium ion channel and its mediators, the different clinical strategy to control acid rebound, and some basic experimental observations performed to study the interplay of ion channels, pumps, as well as mediators during acid secretion. Different aspects of regulation of gastric acid secretion have been focused either in terms of physiology of secretion or molecular interactions. The importance of H pylori infection and its treatment has also been discussed. Furthermore, the relevance of calcium signaling during acid secretion has been reviewed. The entire theme will make anyone understand in detail the gastric secretion machinery in general.

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.

Facile and Efficient Nitration of 4‐Aryl‐1(2H)‐Phthalazinone Derivatives Using Different Catalysts

Different nitration methods were investigated on 4‐(4‐mthoxy‐3‐methyl phenyl)‐1(2H)‐phthalazinone and its derivatives using HNO3 as a nitrating agent with different catalysts. LC–MS/MS has been used to determine the product‘s structure. The results showed that the most suitable catalyst was P2O5 at room temperature to introduce an ortho mono‐nitrated group for the phthalazinone derivatives bearing donating groups on the phenyl ring. In contrast, 4‐halophenyl phthalazinone derivatives gave a high yield of mono‐nitrated products using H2SO4 as a catalyst. All mono‐nitrated products were separated with good to excellent yields, and their structures were confirmed by FT‐IR, NMR, LC‐MS/MS and elemental analyses.

Glyceryl Trinitrate: History, Mystery, and Alcohol Intolerance

Glyceryl trinitrate (GTN) is one of the earliest known treatments for angina with a fascinating history that bridges three centuries. However, despite its central role in the nitric oxide (NO) story as a NO-donating compound, establishing the precise mechanism of how GTN exerts its medicinal benefit has proven to be far more difficult. This review brings together the explosive and vasodilatory nature of this three-carbon molecule while providing an update on the likely in vivo pathways through which GTN, and the rest of the organic nitrate family, release NO, nitrite, or a combination of both, while also trying to explain nitrate tolerance. Over the last 20 years the alcohol detoxification enzyme, aldehyde dehydrogenase (ALDH), has undoubtedly emerged as the front runner to explaining GTN's bioactivation. This is best illustrated by reduced GTN efficacy in subjects carrying the single point mutation (Glu504Lys) in ALDH, which is also responsible for alcohol intolerance, as characterized by flushing. While these findings are significant for anyone following the GTN story, they appear particularly relevant for healthcare professionals, and especially so, if administering GTN to patients as an emergency treatment. In short, although the GTN puzzle has not been fully solved, clinical study data continue to cement the importance of ALDH, as uncovered in 2002, as a key GTN activator.