Acute antiinflammatory and gastric effects of the seleno-organic compound ebselen

Ebselen: A Review on its Synthesis, Derivatives, Anticancer Efficacy and Utility in Combating SARS-COV-2

Ebselen is a selenoorganic chiral compound with antioxidant properties comparable to glutathione peroxidase. It is also known as 2-phenyl-1,2-benzisoselenazol-3(2H)-one. In studies examining its numerous pharmacological activities, including antioxidant, anticancer, antiviral, and anti- Alzheimer's, ebselen has demonstrated promising results. This review's primary objective was to emphasize the numerous synthesis pathways of ebselen and their efficacy in fighting cancer. The data were collected from multiple sources, including Scopus, PubMed, Google Scholar, Web of Science, and Publons. The starting reagents for the synthesis of ebselen are 2-aminobenzoic acid and N-phenyl benzamide. It was discovered that ebselen has the ability to initiate apoptosis in malignant cells and prevent the formation of new cancer cells by scavenging free radicals. In addition, ebselen increases tumor cell susceptibility to apoptosis by inhibiting TNF-α mediated NF-kB activation. Ebselen can inhibit both doxorubicin and daunorubicin-induced cardiotoxicity. Allopurinol and ebselen administered orally can be used to suppress renal ototoxicity and nephrotoxicity. Due to excessive administration, diclofenac can induce malignancy of the gastrointestinal tract, which ebselen can effectively suppress. Recent research has demonstrated ebselen to inhibit viral function by binding to cysteinecontaining catalytic domains of various viral proteases. It was discovered that ebselen could inhibit the catalytic dyad function of Mpro by forming an irreversible covalent bond between Se and Cys145, thereby altering protease function and inhibiting SARS-CoV-2. Ebselen may also inhibit the activation of endosomal NADPH oxidase of vascular endothelial cells, which is believed to be required for thrombotic complications in COVID-19. In this review, we have included various studies conducted on the anticancer effect of ebselen as well as its inhibition of SARS-CoV-2.

Novel 2-Hydroselenonicotinonitriles and Selenopheno[2, 3-b]pyridines: Efficient Synthesis, Molecular Docking-DFT Modeling, and Antimicrobial Assessment

Selenium containing heterocyclic compounds gained great interest as bioactive molecules as of late. This report explores the design, synthesis, characterization, and antimicrobial screening of new pyridine derivatives endowed with selenium moieties. A one-pot multicomponent system with a solvent-free, microwave irradiation environment was employed to afford this series. The spectroscopic techniques were exploited to verify the structures of the synthesized derivatives. Additionally, the agar diffusion method was employed to determine the antimicrobial activity of all the desired compounds. Of all the synthesized molecules, 9b, 12b, 14f, and 16d exhibited well to remarkable antibacterial and antifungal activities. Moreover, derivative 14f demonstrated the most potent antibacterial and antifungal performance. The results were also supported by molecular docking studies, utilizing the MOE (molecular operating environment) which revealed the best binding mode with the highest energy interaction within the binding pocket. Lastly, theoretical DFT calculations were carried out in a gas phase at B3LYP 6-311G (d,p) basis set to predict the molecular geometries and chemical reactivity descriptors. DFT results have been used to illustrate that molecular docking findings and biological activity assessments.

Toxicology and pharmacology of synthetic organoselenium compounds: an update

Here, we addressed the pharmacology and toxicology of synthetic organoselenium compounds and some naturally occurring organoselenium amino acids. The use of selenium as a tool in organic synthesis and as a pharmacological agent goes back to the middle of the nineteenth and the beginning of the twentieth centuries. The rediscovery of ebselen and its investigation in clinical trials have motivated the search for new organoselenium molecules with pharmacological properties. Although ebselen and diselenides have some overlapping pharmacological properties, their molecular targets are not identical. However, they have similar anti-inflammatory and antioxidant activities, possibly, via activation of transcription factors, regulating the expression of antioxidant genes. In short, our knowledge about the pharmacological properties of simple organoselenium compounds is still elusive. However, contrary to our early expectations that they could imitate selenoproteins, organoselenium compounds seem to have non-specific modulatory activation of antioxidant pathways and specific inhibitory effects in some thiol-containing proteins. The thiol-oxidizing properties of organoselenium compounds are considered the molecular basis of their chronic toxicity; however, the acute use of organoselenium compounds as inhibitors of specific thiol-containing enzymes can be of therapeutic significance. In summary, the outcomes of the clinical trials of ebselen as a mimetic of lithium or as an inhibitor of SARS-CoV-2 proteases will be important to the field of organoselenium synthesis. The development of computational techniques that could predict rational modifications in the structure of organoselenium compounds to increase their specificity is required to construct a library of thiol-modifying agents with selectivity toward specific target proteins.

Synergistic gastroprotective activity of methanolic extract of a mixture of Melastoma malabathricum and Muntingia calabura leaves in rats

BACKGROUND

Melastoma malabathricum L. (family Melastomaceae; MM) and Muntingia calabura L. (family Elaeocarpaceae; MC) have been separately reported to possess gastroprotective activity. In an attempt to develop a pharmaceutical product with antiulcer potential, the synergistic gastroprotective activity of methanolic extract of a mixture of MM and MC (MMMC) at various ratios was evaluated in rat models.

METHODS

Rats were pre-treated orally with 2% Tween 80 (vehicle), 100 mg/kg ranitidine (reference drug) or MMMC (ratios of 1:1, 1:3 and 3:1 (v/v); doses of 15, 150 or 300 mg/kg) and then subjected to the ethanol-induced gastric ulcer or pyloric ligation assays. Stomach of rats from the former assay was collected and subjected to the macroscopic and microscopic observations, and enzymatic and non-enzymatic antioxidant studies while the gastric juice content and tissue from the latter assay were subjected to the antisecretory activity study. The UHPLC analysis of MMMC was also performed.

RESULT

MMMC, in the ratio 1:1, demonstrated the most effective (P < 0.001) gastroprotective activity indicated by the highest reduction in ethanol-induced ulcer area formation. These macroscopic findings were supported by the microscopic observations. Except for pH and total acidity, MMMC also significantly (P < 0.001) reduced the volume of gastric content but increased the gastric wall mucus content in the pyloric-ligation test. MMMC also demonstrated remarkable antioxidant activity indicated by the highest total phenolic content (TPC) value and oxygen radical absorbance capacity (ORAC) activity with the recorded IC₅₀ value of approximately 53 μg/mL for the 2,2- diphenyl-1-picrylhydrazyl (DPPH) scavenging activity. MMMC also improved the catalase (CAT), superoxide dismutase (SOD), glutathione (GSH), prostaglandin E2 (PGE2) and malondialdehyde (MDA) activities of the gastric tissue intoxicated by ethanol. UHPLC analysis of MMMC confirmed the presence several flavonoid-based bioactive compounds.

CONCLUSION

MMMC, at the ratio of 1:1 (v/v), exerts gastroprotective activity partly by activating its antisecretory and antioxidant activities, and via modulation of the gastric tissue endogenous antioxidant system.

A Summary of New Findings on the Biological Effects of Selenium in Selected Animal Species-A Critical Review

Selenium is an essential trace element important for many physiological processes, especially for the functions of immune and reproductive systems, metabolism of thyroid hormones, as well as antioxidant defense. Selenium deficiency is usually manifested by an increased incidence of retention of placenta, metritis, mastitis, aborts, lowering fertility and increased susceptibility to infections. In calves, lambs and kids, the selenium deficiency demonstrates by WMD (white muscle disease), in foals and donkey foals, it is associated with incidence of WMD and yellow fat disease, and in pigs it causes VESD (vitamin E/selenium deficiency) syndrome. The prevention of these health disorders can be achieved by an adequate selenium supplementation to the diet. The review summarizes the survey of knowledge on selenium, its biological significance in the organism, the impact of its deficiency in mammalian livestock (comparison of ruminants vs. non-ruminants, herbivore vs. omnivore) and possibilities of its peroral administration. The databases employed were as follows: Web of Science, PubMed, MEDLINE and Google Scholar.

FLAVONOIDS AND ANTI-OXIDANT ACTIVITY MEDIATED GASTROPROTECTIVE ACTION OF LEATHERY MURDAH, TERMINALIA CORIACEA (ROXB.) WIGHT & ARN. LEAF METHANOLIC EXTRACT IN RATS

ABSTRACT BACKGROUND Leathery Murdah, Terminalia coriacea (Roxb.) Wight & Arn. from family Combretaceae is used in Ayurveda and Siddha traditional systems of medicine to heal ulcers. OBJECTIVE The present study was conducted to assess the gastroprotective effect and understand the fundamental mechanism of action of Leathery Murdah, Terminalia coriacea (Roxb.) Wight & Arn. Leaf Methanolic Extract. METHODS The test extract was screened for anti-ulcer activity by Aspirin induced ulcerogenesis in pyloric ligation and ethanol induced gastric ulcers at three doses - 125, 250, and 500 mg/kg, p.o. using Ranitidine 50 mg/kg and Misoprostol 100 μg/kg as standard drug in respective models. Seven parameters were carefully examined, that is, ulcer index, total protein, mucin, catalase, malondialdehyde, and superoxide dismutase levels and histopathology. High Performance Liquid Chromatographic - Ultra Violet profiling and Liquid Chromatography - Mass Spectral analysis of crude Terminalia coriacea leaves methanolic extract were carried out as a part of chemical characterization to identify bioactive compounds. RESULTS All the test doses exhibited significant gastroprotective function, particularly the higher doses demonstrated improved action. The results revealed a significant increase in the levels of catalase, superoxide dismutase, and Mucin with reduction in ulcer index, the levels of total protein, and malondialdehyde. Histopathological observations also illustrated the gastroprotective effect of Terminalia coriacea leaves methanolic extract. CONCLUSION Terminalia coriacea leaves methanolic extract exhibited strong anti-oxidant and anti-secretory activities mediated gastroprotection besides inducing the gastric mucosal production. The observed pharmacological response can be attributed to the flavonoidal compounds namely - Quercetin-3-O-rutinoside, Luteolin-7-O-glucoside, Myricetin hexoside, Quercetin-3-O-glucoside, Isorhamnetin-3-O-rhamnosylglucoside and Isorhamnetin-3-O-glucoside identified in the extract for the first time with High Performance Liquid Chromatographic - Ultra Violet and Liquid Chromatography - Mass Spectral analysis.

Progress does not just come in giant leaps: adapting techniques for the study of inflammation to novel applications

INTRODUCTION

Discussion of the relevance of suitable experimental models for the effective translation of drug effects to clinical inflammatory diseases has a long history. Much emphasis is placed these days on genetically transformed mice, which may have developmental drawbacks. But are established models redundant?

FINDINGS

Drawn from personal experience, examples are provided of the success of tinkering with technology in the context of inflammation. These include the use of specific dietary deficiency conditions, the development of new applications for established drugs and the introduction of a variety of readouts to assess outcome in studies on established disease models. Such approaches have been used to demonstrate inflammation-modulating effects of prostaglandin E, in the development of ebselen, for the introduction of immunomodulatory macrolide drugs and in new approaches to the therapy of multiple sclerosis.

CONCLUSION

Fine tuning of experimental approaches and evaluation technologies can often still provide innovative, clinically relevant insights into the potential beneficial effects of drugs and pharmacological agents.

Release-active dilutions of diclofenac enhance anti-inflammatory effect of diclofenac in carrageenan-induced rat paw edema model

The study was aimed to investigate the effect of technologically treated diclofenac (release-active dilutions of diclofenac (RAD of diclofenac)) on anti-inflammatory activity of diclofenac in carrageenan-induced rat paw edema model. Ninety male Wistar albino rats (6-8 weeks) divided into nine groups (n = 10) were used. Anti-inflammatory activity was assessed at 1, 2, 3, 4, and 6 h after subplantar injection of carrageenan (0.1 ml of a 1 % solution in normal saline). Diclofenac alone was studied at 5 and 20 mg/kg, RAD of diclofenac alone at 7.5 ml/kg and their combination at 5 and 7.5 ml/kg, respectively. Diclofenac reduced (p < 0.05 at least) paw edema at all time points. RAD of diclofenac enhanced (p < 0.05) anti-inflammatory effect of diclofenac (5 mg/kg) at 2, 4, and 6 h on concurrent and at 2 and 4 h on sequential administration. Moreover at 2 h, anti-inflammatory effect of combination treatment reached values comparable to those of diclofenac (20 mg/kg). In conclusion, RAD of diclofenac enhanced anti-inflammatory effect of diclofenac.

Prostaglandin analogous and antioxidant activity mediated gastroprotective action of Tabernaemontana divaricata (L.) R. Br. flower methanolic extract against chemically induced gastric ulcers in rats

The present study was conducted to evaluate the antiulcerogenic effect and recognize the basic mechanism of action of Tabernaemontana divaricata (L.) R. Br. flowers. T. divaricata flower methanolic extract (TDFME) was screened for antiulcer activity versus aspirin and ethanol induced gastric ulcers at three doses—125, 250, and 500 mg/kg—orally using misoprostol as a standard. Besides histopathological examination, seven parameters, that is, ulcer index, total protein, nonprotein sulphhydryls, mucin, catalase, malondialdehyde, and superoxide dismutase levels, were estimated. In addition to HPLC profiling, GC-MS analysis and electrospray ionization—high resolution mass spectral (ESI-HRMS) analysis of crude TDFME were carried out in an attempt to identify known phytochemicals present in the extract on the basis of m/z value. The results revealed a significant increase in the levels of catalase, superoxide dismutase, mucin, and nonprotein sulphhydryls, while they revealed a reduction in ulcer index, the levels of total protein, and malondialdehyde. Histopathological observations also demonstrated the protective effect. Though all the doses of TDFME exhibited gastroprotective function, higher doses were found to be more effective. Mass spectral analysis gave a few characteristic m/z values suggesting the presence of a few known indole alkaloids, while HPLC profiling highlighted the complexity of the extract. TDFME was found to exhibit its gastroprotective effect through antioxidant mechanism and by enhancing the production of gastric mucous.

Protective effect of ebselen, a seleno-organic compound, against the progression of acute gastric mucosal lesions induced by compound 48/80, a mast cell degranulator, in rats

The protective effect of ebselen, which possesses glutathione peroxidase-like activity and antioxidative and anti-inflammatory properties, against the progression of acute gastric mucosal lesions was examined in rats with a single intraperitoneal injection of compound 48/80 (0.75 mg/kg). Ebselen (50, 100 or 200 mg/kg) was orally administered 0.5 h after compound 48/80 treatment, at which time gastric mucosal lesions appeared. Post-administered ebselen suppressed gastric mucosal lesion progression at 3 h after compound 48/80 treatment dose-dependently, although no dose of ebselen affected the decreased gastric mucosal blood flow and increased serum serotonin and histamine concentrations found at 3 h after the treatment. A decrease in Se-glutathione peroxidase activity and increases in myeloperoxidase and xanthine oxidase activities and the concentration of thiobarbituric acid reactive substances were found in gastric mucosal tissues at 0.5 h after compound 48/80 treatment, and these changes were further enhanced at 3 h. Post-administered ebselen attenuated all these changes found at 3 h after compound 48/80 treatment dose-dependently. The present results indicate that ebselen exerts a protective effect against the progression of compound 48/80-induced acute gastric mucosal lesions in rats, and they suggest that this protective effect of ebselen could be due to its glutathione peroxidase-like activity and its antioxidative and anti-inflammatory properties.

Preventive effect of ebselen on acute gastric mucosal lesion development in rats treated with compound 48/80

The preventive effect of ebselen, a seleno-organic compound, which is known to possess glutathione peroxidase-like activity and antioxidative and anti-inflammatory properties, on the development of acute gastric mucosal lesions was examined in rats with a single injection of compound 48/80 (0.75 mg/kg, i.p.), a mast cell degranulator. Pre-administration of ebselen (p.o.) at a dose of 50 or 100 mg/kg, but not 10 mg/kg, prevented gastric mucosal lesion development at 3 h, but not gastric mucosal lesion formation at 0.5 h, after compound 48/80 injection, although any dose of pre-administered ebselen did not affect decreased gastric mucosal blood flow and increased serum serotonin and histamine concentrations found at 0.5 and 3 h after compound 48/80 injection. A decrease in Se-glutathione peroxidase activity and increases in the activities of myeloperoxidase, an index of tissue neutrophil infiltration, and xanthine oxidase and the concentration of thiobarbituric acid reactive substances, an index of lipid peroxidation, were found in gastric mucosal tissues at 0.5 h after compound 48/80 injection and these changes were further enhanced at 3 h. Pre-administration of ebselen (p.o.) at a dose of 50 or 100 mg/kg, but not 10 mg/kg, attenuated all these changes found at 3 h after compound 48/80 injection. These preventive effects of ebselen occurred in a dose-dependent manner. The present results indicate that pre-administered ebselen prevents the development of compound 48/80-induced acute gastric mucosal lesions in rats, and suggest that this preventive effect of ebselen could be due to its glutathione peroxidase-like activity and antioxidative and anti-inflammatory properties.

Lipid peroxidation in presence of ebselen

Lipid peroxidation is initiated by cell damage. After homogenisation of porcine heart tissue in aqueous solution we observed the same lipid peroxidation products as detected after heart infarction. We used this observation to study the influence of ebselen (2-phenyl-1,2-benzoisoselenazol-3-(2H)-one) on the generation of oxidatively derived monohydroxy fatty acids and alpha-hydroxyaldehydes, typical lipid peroxidation (LPO) products. Heart tissue was homogenised before and after enzyme destruction and with addition of ebselen. The obtained LPO products were analysed by GC/MS after appropriate derivatisation and quantified by using internal standards. The amount of monohydroxy fatty acids and alpha-hydroxyaldehydes increased considerably in the porcine heart homogenates in which the enzymes were kept active. Addition of ebselen caused an additional significant increase of hydroxy fatty acids, while the increase of aldehydic compounds was less. These results confirm the glutathione peroxidase-like activity of ebselen but demonstrate also that it does not prevent lipid peroxidation.

Molecular actions of ebselen--an antiinflammatory antioxidant

1. Ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-one) is a non-toxic seleno-organic drug with antiinflammatory, antiatherosclerotic and cytoprotective properties. 2. Ebselen and some of its metabolites are effective reductants of hydroperoxides including those arising in biomembranes and lipoproteins. 3. By reactions with hydroperoxides and thiols several interconversion cycles are formed which include ebselen metabolites with varying oxidation number of the selenium. 4. In the presence of thiols ebselen mimics the catalytic activities of phospholipid hydroperoxide glutathione peroxidase. 5. Ebselen inhibits at low concentrations a number of enzymes involved in inflammation such as lipoxygenases, NO synthases, NADPH, oxidase, protein kinase C and H+/K(+)-ATPase. The inhibitions are manifested on the cellular level and may contribute to the antiinflammatory potential of ebselen.

Ebselen, a seleno-organic compound, protects against ethanol-induced murine gastric mucosal injury in both in vivo and in vitro systems

The inhibitory effect of the seleno-organic compound ebselen on ethanol-induced murine gastric mucosal injury was examined. In an in vivo study, absolute ethanol (50 microliters/mouse, oral) produced marked gastric mucosal necrosis along with hemorrhage or edema and elevations in both lipid peroxide and peptidoleukotriene levels in the fundic mucosa. Pretreatment with ebselen (30 and 100 mg/kg, oral) significantly prevented this gastric mucosal injury and, further, remarkably decreased the elevated lipid peroxide and peptidoleukotriene levels. In an in vitro study using a murine gastric surface mucous cell line GSM06, exposure to ethanol concentration dependently elicited cell damage (7.5-17.5% ethanol) and an increase in lipid peroxides without alterations in peptidoleukotrienes (15% ethanol). Addition of ebselen (10 and 100 microM) to this system (15% ethanol) significantly inhibited the cell damage and completely prevented the increase in lipid peroxide level. These results indicate that ebselen protects against murine gastric mucosal injury both in vivo and in vitro, and that this protection may be related at least in part to its inhibitory action on lipid peroxides.

Ebselen is a specific inhibitor of LTB4-mediated migration of human neutrophils

Ebselen is a seleno-organic anti-inflammatory compound with glutathione peroxidase-like activity that has the unique characteristic of mediating the isomerization of 5-HETE and LTB4 to their biologically inactive trans isomers, both directly in fluid phase and indirectly through metabolic pathways in stimulated peripheral blood leukocytes. LTB4 is an inflammatory mediator with potent chemotactic activity for neutrophilic leukocytes. We studied the effects of ebselen on the chemotactic and chemokinetic responses with human-blood-derived neutrophils. With the use of 120-microns-thick 5-microns-pore durapore filters and low BSA concentrations (0.05%) in the chemotaxis buffers, ebselen was evaluated for its effect on both chemotactic and chemokinetic responses to LTB4, C5a, and fMLP. Ebselen at 3-20 microM concentrations inhibited both chemotactic and chemokinetic responses to optimal concentrations of LTB4 without altering chemotactic responses to C5a or fMLP. Likewise, ebselen at 20 microM specifically inhibited LTB4-stimulated transendothelial migration of neutrophils, while not altering responses to C5a nor fMLP.

Antisecretory and antiulcer effects of ebselen, a seleno-organic compound, in rats

The effects of ebselen (2-phenyl-1,2-benzisoselenazol-3(2H)-on), a metal-containing organic compound, on gastric secretion and gastric ulceration were examined in rats. Intraduodenal ebselen (30 to 300 mg/kg) significantly and dose-dependently inhibited gastric secretion in pylorus-ligated rats. Both aspirin- and water-immersion restraint stress-induced ulcers were significantly prevented by oral administration of ebselen at doses equivalent to the antisecretory doses. These results indicate that the antisecretory effect of ebselen underlies its antiulcer effect in these models.

Studies on the mechanism of anti-inflammatory and anti-ulcer activity of Pluchea indica--probable involvement of 5-lipooxygenase pathway

The effect of the methanolic fraction of Pluchea indica Less. root extract was evaluated on various models of inflammation and ulcer in vivo to assess the role of P. indica on the 5-lipoxygenase pathway of prostaglandin synthesis. Studies presented here reveal significant antiinflammatory activity of the fraction on Arachidonic acid, Platelet activation factor and Compound 48/80-induced paw oedema. There was significant inhibition of spontaneous as well as compound 48/80-induced histamine release from mast cells. Ulcer studies revealed significant protective action of the fraction on indomethacin, alcohol and indomethacin-alcohol induced ulceration. There was significant decrease of gastric volume and acidity in pylorus ligated rats. Studies also showed, significant protective action of the same on gastric mucosa.