New insight into the control of peptic ulcer by targeting the histamine H2 receptor

The effects of dragon fruit (Hylocereus polyrhizus) extract on indomethacin-induced stomach ulcer in rats

The aim of this study was to investigate the effects of red dragon fruit (Hylocereus polyrhizus) extract (DFE) on the stomach in ulcer model induced by indomethacin in rats. Effects of DFE were evaluated in indomethacin-induced gastric damage model on Sprague-Dawley rats. Experimental model: all rats were fasted for 24 h. At the end of this period, DFE was administered to the ulcer-induced groups. One hour after this application, a dose of 25 mg/kg of indomethacin was applied by oral gavage to all groups except the HEALTHY and DFE1000 groups. Six hours after indomethacin administration, the rats were euthanized with high-dose anesthesia and the experiment was terminated. Macroscopic and microscopic analyses for investigating ulcerative area, molecular and biochemical analyses for oxidative damages investigation and molecular analyses for the effect mechanism of indomethacin and DFE were conducted on stomach tissues in the study. While oxidative stress-associated markers such as MDA, BAX, and Caspase 3 increased dramatically in the indomethacin group, GSH antioxidant levels decreased. It was observed that these parameters were significantly improved in DFE 500 mg/kg and DFE 1000 mg/kg groups compared to ulcer group, and the results of especially DFE 1000 mg/kg group were similar to famotidine group. We observed that our histopathological findings also supported all our other findings. Dragon fruit extract was protected against indomethacin-induced ulcer damage by decreased MDA levels, increased GSH levels, and inhibition of Caspase 3, BAX, and Cox-2, and activation of Cox-1. PRACTICAL APPLICATIONS: People of all ages around the world suffer from gastric ulcer which is one of the most common gastrointestinal ailments. The etiological factors of the disease are using of cigarette and alcohol, nutritional deficiencies, infections, and using non-steroidal anti-inflammatory drugs which use frequent and indiscriminate. Indomethacin is one of the NSAIDs and is commonly preferred to induce ulcer modeling in rats due to its gastric toxicity potential. Current anti-ulcer drugs have many serious side effects. Patients who suffered from gastric ulcer tend to discontinue the drug because of side effects. Therefore, patients need new agents that are non-toxic, have few side effects, and are easily accessible anti-ulcer drugs. Dragon fruit, as a medicinal herb, is highly valuable and widely used in traditional medicine, and may provide gastroprotective activity. Studies have shown that H. polyrhizus has antioxidant activities. We consider the effects of dragon fruit extract (DFE) to be a therapeutic drug for an indomethacin-induced ulcer model.

Nitrile-containing pharmaceuticals: target, mechanism of action, and their SAR studies

The nitrile group is an important functional group widely found in both pharmaceutical agents and natural products. More than 30 nitrile-containing pharmaceuticals have been approved by the FDA for the management of a broad range of clinical conditions in the last few decades. Incorporation of a nitrile group into lead compounds has gradually become a promising strategy in rational drug design as it can bring additional benefits including enhanced binding affinity to the target, improved pharmacokinetic profile of parent drugs, and reduced drug resistance. This paper reviews the existing drugs with a nitrile moiety that have been approved or in clinical trials, involving their targets, molecular mechanism of pharmacology and SAR studies, and classifies them into different categories based on their clinical usages.

Molecular Modeling of Histamine Receptors-Recent Advances in Drug Discovery

The recent developments of fast reliable docking, virtual screening and other algorithms gave rise to discovery of many novel ligands of histamine receptors that could be used for treatment of allergic inflammatory disorders, central nervous system pathologies, pain, cancer and obesity. Furthermore, the pharmacological profiles of ligands clearly indicate that these receptors may be considered as targets not only for selective but also for multi-target drugs that could be used for treatment of complex disorders such as Alzheimer's disease. Therefore, analysis of protein-ligand recognition in the binding site of histamine receptors and also other molecular targets has become a valuable tool in drug design toolkit. This review covers the period 2014-2020 in the field of theoretical investigations of histamine receptors mostly based on molecular modeling as well as the experimental characterization of novel ligands of these receptors.

The Effect of Deuteration on the H2 Receptor Histamine Binding Profile: A Computational Insight into Modified Hydrogen Bonding Interactions

We used a range of computational techniques to reveal an increased histamine affinity for its H₂ receptor upon deuteration, which was interpreted through altered hydrogen bonding interactions within the receptor and the aqueous environment preceding the binding. Molecular docking identified the area between third and fifth transmembrane α-helices as the likely binding pocket for several histamine poses, with the most favorable binding energy of −7.4 kcal mol⁻¹ closely matching the experimental value of −5.9 kcal mol⁻¹. The subsequent molecular dynamics simulation and MM-GBSA analysis recognized Asp98 as the most dominant residue, accounting for 40% of the total binding energy, established through a persistent hydrogen bonding with the histamine −NH₃⁺ group, the latter further held in place through the N–H∙∙∙O hydrogen bonding with Tyr250. Unlike earlier literature proposals, the important role of Thr190 is not evident in hydrogen bonds through its −OH group, but rather in the C–H∙∙∙π contacts with the imidazole ring, while its former moiety is constantly engaged in the hydrogen bonding with Asp186. Lastly, quantum-chemical calculations within the receptor cluster model and utilizing the empirical quantization of the ionizable X–H bonds (X = N, O, S), supported the deuteration-induced affinity increase, with the calculated difference in the binding free energy of −0.85 kcal mol⁻¹, being in excellent agreement with an experimental value of −0.75 kcal mol⁻¹, thus confirming the relevance of hydrogen bonding for the H₂ receptor activation.

A Review of the Role of Flavonoids in Peptic Ulcer (2010-2020)

Peptic ulcers are characterized by erosions on the mucosa of the gastrointestinal tract that may reach the muscle layer. Their etiology is multifactorial and occurs when the balance between offensive and protective factors of the mucosa is disturbed. Peptic ulcers represent a global health problem, affecting millions of people worldwide and showing high rates of recurrence. Helicobacter pylori infection and the use of non-steroidal anti-inflammatory drugs (NSAIDs) are one of the most important predisposing factors for the development of peptic ulcers. Therefore, new approaches to complementary treatments are needed to prevent the development of ulcers and their recurrence. Natural products such as medicinal plants and their isolated compounds have been widely used in experimental models of peptic ulcers. Flavonoids are among the molecules of greatest interest in biological assays due to their anti-inflammatory and antioxidant properties. The present study is a literature review of flavonoids that have been reported to show peptic ulcer activity in experimental models. Studies published from January 2010 to January 2020 were selected from reference databases. This review refers to a collection of flavonoids with antiulcer activity in vivo and in vitro models.

Multiple omics analysis reveals that high fiber diets promote gluconeogenesis and inhibit glycolysis in muscle

BACKGROUND

Meat quality is a complex trait affected by genotypic and environmental factors. In a previous study, it was found that feedstuffs have various effects on the growth rate and meat quality of lambs. However, the underlying mechanisms are still not entirely clear.

RESULTS

In this study, to investigate the mechanisms that impact meat quality in twin sheep fed either with high fiber low protein (HFLP) forage (Ceratoides) or low fiber high protein (LFHP) forage (alfalfa) diets, multi omics techniques were utilized for integration analysis based on the feed nutritional value and the sheep microbiome, transcriptome, metabolome, and fatty acid profile. Results showed that the production performance and the muscle components of lambs were significantly affected by feeds. The essential fatty acid (linoleic acid and arachidonic acid) content of the muscle, based on gas chromatography-mass spectrometry analysis, was increased when lambs were fed with HFLP. The microbes in the lambs' rumen fed a HFLP diet were more diverse than those of the LFHP fed group. Besides, the ratio of Bacteroidetes and Firmicutes in the rumen of the sheep fed a LFHP diet was 2.6 times higher than that of the HFLP fed group. Transcriptome analysis of the muscle revealed that the genes related to glucose metabolic processes and fatty acid biosynthesis were significantly differentially expressed between the two groups. Potential cross talk was found between the sfour omics data layers, which helps to understand the mechanism by which feedstuffs affect meat quality of lambs.

CONCLUSION

Feed systems may affect the epigenetic regulation of genes involved in the glucose metabolic pathway. HFLP feeds could induce gluconeogenesis to maintain glucose levels in blood, resulting in decreased fat content in muscle. The multiple omics analysis showed that the microbiota structure is significantly correlated with the metabolome and gene expression in muscle. This study laid a theoretical foundation for controlling the nutrient intake of sheep; it suggested that its fatty acid spectrum modifications and the removal of meat quality detrimental material could guide sheep feeding for functional mutton.

Histamine in the kidneys: what is its role in renal pathophysiology?

Starting with a role for histamine role in renal haemodynamics, evidence has accumulated, over time, suggesting a wider range of actions on renal function and this has renewed interest in the pathophysiological role of histamine in the kidney. Here we provide an up-to-date review of this topic. As the kidney expresses enzymes that synthesize and metabolise histamine, along with its receptors, all the components for histaminergic transmission are present in this tissue. The distribution of histamine receptors matches a wide range of effects. We address the questions of the redundancy of H1 and H2 receptors in renal haemodynamics, the complementary role of H1 and H4 receptors in renal filtration and reabsorption, and the dichotomy between local and neuronal H1 and H3 receptors. Experimental models of renal disease raise the possibility of new therapeutic approaches based on histamine. The effects of histamine on renal function are not yet fully understood and their elucidation is still ongoing. LINKED ARTICLES: This article is part of a themed section on New Uses for 21st Century. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.3/issuetoc.

What We Know and What We Need to Know about Aromatic and Cationic Biogenic Amines in the Gastrointestinal Tract

Biogenic amines derived from basic and aromatic amino acids (B/A-BAs), polyamines, histamine, serotonin, and catecholamines are a group of molecules playing essential roles in many relevant physiological processes, including cell proliferation, immune response, nutrition and reproduction. All these physiological effects involve a variety of tissue-specific cellular receptors and signalling pathways, which conforms to a very complex network that is not yet well-characterized. Strong evidence has proved the importance of this group of molecules in the gastrointestinal context, also playing roles in several pathologies. This work is based on the hypothesis that integration of biomedical information helps to reach new translational actions. Thus, the major aim of this work is to combine scientific knowledge on biomolecules, metabolism and physiology of the main B/A-BAs involved in the pathophysiology of the gastrointestinal tract, in order to point out important gaps in information and other facts deserving further research efforts in order to connect molecular information with pathophysiological observations.