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The one-pot multicomponent synthetic strategy of organoselenium compounds represents an alternative and robust protocol to the conventional multistep methods. During the last decade, a potential advance has been made in this domain. This review discusses the latest advances in the polymerization, metal, and metal-free one-pot multicomponent synthesis of organoselenium compounds. [ABSTRACT FROM AUTHOR]

Introduction: Selenium is, at the same time, toxic if ingested in great amounts and an essential micronutrient to several metabolic processes in both animals and humans. Selenium deficiency is being related to an increased chance to develop diseases such as cancer, diabetes, cardiovascular diseases, among others. In medicinal chemistry, selenium has gained in importance since the discovery of ebselen, ethaselen, and diphenyl disselenide. Objectives: This review aims to compile the main data available on the literature on the importance of selenium to human life, providing an overview of its biological role, the main diseases related to its deficiency, as well as the medicinal chemistry of the three most prominent organoselenium compounds. Methodology: Articles and academic thesis, published in English and Portuguese, showing the role of selenium in biochemistry and medicinal chemistry were recovered from SciFinder, PubMed, and Google Scholar. Results: So far, 25 selenoproteins that play a biological role in humans and animals were identified. It is known that selenium deficiency is directly related not only to a predisposition to developing some diseases but is also the main cause of illnesses such as Keshan and Kashin-Beck. In the medicinal chemistry field, the development of selenium-containing bioactive compounds with low toxicity was proved possible. Conclusion: Selenium is an essential element to life, being the core component of selenoproteins. The understanding of the biochemical processes modulated by those proteins is mandatory to medicinal chemists willing to develop potent organoselenium drugs. [ABSTRACT FROM AUTHOR]

[Display omitted] • A series of organoselenium compounds based on ART and Se functionalities (-SeCN and -SeCF 3) were designed and synthesized. • Compound 2c exhibited potent antiproliferative activity and good free radical scavenging activity. • Compound 2c induced ferroptosis in HCT116 cells by inhibiting the expression of GPX4 protein and mRNA levels. A series of organoselenium compounds based on the hybridization of artesunate (ART) scaffolds and Se functionalities (–SeCN and –SeCF 3) were synthesized. The redox properties of artesunate-SeCN and artesunate-SeCF 3 derivatives were conducted by 2, 2-didiphenyl-1-picrylhydrazyl (DPPH), and the results showed that compounds 2c , 2f and 3e have a good free radical scavenging activity. Their cytotoxicity was evaluated against four types of cancer cell lines, SW480 (human colon adenocarcinoma cells), HCT116 (human colorectal adenocarcinoma cells), HepG2 (human hepatocellular carcinoma cells), MCF-7 (human breast cancer cells). The MTT results showed that compared with ART and 5-FU, compound 2c exhibited potent in vitro antiproliferative activity in SW480, HCT116, and MCF-7 cancer cell lines, and was thus chose for further antitumor mechanism investigation. The antitumor mechanism study revealed that compound 2c induced ferroptosis in HCT116 cells by inhibiting the expression of GPX4 protein, accompanying by the up-regulation of intracellular ROS levels. Mitochondria in HCT116 cells exhibit depolarization of mitochondrial membrane potential (MMP) and ultrastructural changes in morphology, which indicated that 2c resulted in mitochondrial dysfunction and ferroptosis. Moreover, 2c could increase the levels of lipid peroxidation and ferrous ion, which further confirm that compound 2c may exert its antitumor effect through ferroptosis. Overall, these results suggest that the artesunate-Se candidates could provide promising new lead derivatives for further potential anticancer drug development. [ABSTRACT FROM AUTHOR]

Organoselenium compounds are highly versatile and have been extensively used in pharmaceutical industry, synthetic intermediates and catalysts. Accordingly, the development of efficient and straightforward strategies for constructing these compounds is highly desirable. Lewis base catalyzed and Brønsted acid controlled chemodivergent electrophilic selenofunctionalizations of alkynes were developed for the first time. More details are discussed in the article by Chen et al. on page 1623—1629. [ABSTRACT FROM AUTHOR]

3-Methylindole (Skatole), a degradation product of tryptophan produced by intestinal microbial activity, significantly contributes to odor nuisance. Its adverse effects on animal welfare, human health, and environmental pollution have been noted. However, it is still unclear whether the intestinal microbiota mediates the impact of selenium (Se) on skatole production and what the underlying mechanisms remain elusive. A selenized glucose (SeGlu) derivative is a novel organic selenium compound. In this study, a diverse range of dietary SeGlu-treated levels, including SeGlu-deficient (CK), SeGlu-adequate (0.15 mg Se per L), and SeGlu-supranutritional (0.4 mg Se per L) conditions, were used to investigate the complex interaction of SeGlu on intestinal microbiome and serum metabolome changes in male Sprague-Dawley (SD) rats. The study showed that SeGlu supplementation enhanced the antioxidant ability in rats, significantly manifested in the increases of the activity of catalase (CAT) and glutathione peroxidase (GSH-Px), while no change in the level of malonaldehyde (MDA). Metagenomic sequencing analysis verified that the SeGlu treatment group significantly increased the abundance of beneficial microorganisms such as Clostridium , Ruminococcus , Faecalibacterium , Lactobacillus, and Alloprevotella while reducing the abundance of opportunistic pathogens such as Bacteroides and Alistipes significantly. Further metabolomic analysis revealed phenylalanine, tyrosine, and tryptophan biosynthesis changes in the SeGlu treatment group. Notably, the biosynthesis of indole, a critical pathway, was affected by SeGlu treatment, with several crucial enzymes implicated. Correlation analysis demonstrated strong associations between specific bacterial species - Treponema , Bacteroides, and Ruminococcus, and changes in indole and derivative concentrations. Moreover, the efficacy of SeGlu-treated fecal microbiota was confirmed through fecal microbiota transplantation, leading to a decrease in the concentration of skatole in rats. Collectively, the analysis of microbiota and metabolome response to diverse SeGlu levels suggests that SeGlu is a promising dietary additive in modulating intestinal microbiota and reducing odor nuisance in the livestock and poultry industry. [Display omitted] • Microbiota and metabolome response to diverse selenized glucose levels. • Carbohydrate, lipid, and amino acid pathways altered by selenized glucose treatment. • Notable Firmicutes increase and Bacteroidetes decrease in selenized glucose supplement group. • Selenized glucose affects indole pathway and decreases fecal skatole concentration, correlating with specific bacteria. [ABSTRACT FROM AUTHOR]

In this study, we have developed a redox-sensitive (RS) liposomal doxorubicin formulation by incorporating 10,10′-diselanediylbis decanoic acid (DDA) organoselenium compound as the RS moiety. Hence, several RS liposomal formulations were prepared by using DOPE, HSPC, DDA, mPEG 2000 -DSPE, and cholesterol. In situ drug loading using a pH gradient and citrate complex yielded high drug to lipid ratio and encapsulation efficiency (100 %) for RS liposomes. Liposomal formulations were characterized in terms of size, surface charge and morphology, drug loading, release properties, cell uptake and cytotoxicity, as well as therapeutic efficacy in BALB/c mice bearing C26 tumor cells. The formulations showed an average particle size of 200 nm with narrow size distributions (PDI < 0.3), and negative surface charges varying from −6 mV to −18.6 mV. Our study confirms that the presence of the DDA compound in liposomes is highly sensitive to hydrogen peroxide at 0.1 % w/v, resulting in a significant burst release of up to 40 %. The in vivo therapeutic efficacy study in BALB/c mice bearing C26 colon carcinoma confirmed the promising function of RS liposomes in the tumor microenvironment which led to a prolonged median survival time (MST). The addition of hydrogenated soy phosphatidylcholine (HSPC) with a high transition temperature (Tm: 52–53.5 °C) extended the MST of our 3-component formulation of F14 (DOPE/HSPC/DDA) to 60 days in comparison to Caelyx (PEGylated liposomal Dox), which is not RS-sensitive (39 days). Overall, HSPC liposomes bearing RS-sensitive moiety enhanced therapeutic efficacy against colon cancer in vitro and in vivo. This achievement unequivocally underscores the criticality of high-TM phospholipids, particularly HSPC, in significantly enhancing liposome stability within the bloodstream. In addition, RS liposomes enable the on-demand release of drugs, leveraging the redox environment of tumor cells, thereby augmenting the efficacy of the formulation. [Display omitted] • Reactive oxygen species (ROS) is overexpressed in tumor microenvironment (TME) considered as the physical targeting of redox-sensitive nano-carriers such as liposomes. • 10,10'-diselanediylbis decanoic acid, is an organic compound composed of a diselenide bond which is cleaved in the presence of ROS. • Release studies indicated a burst release of roughly 40 % in the presence of 0.1 % hydrogen peroxide at pH 6.5. • Inadequate release of doxorubicin from Doxil®/Caelyx®, is bypassed by manufacturing redox-sensitive liposomes that can undergo structural cleavage in TME. [ABSTRACT FROM AUTHOR]

• New organoselenium bicycle 7,8-dimethoxy-9-selenabicyclo[4.2.1]nonane 1 is prepared. • Bicycle 1 is oxidized much faster than its 2,6-dimethoxy bicyclo[3.3.1]nonane isomer 2. • GPx-like activity of 1 assessed from oxidation of dithiothreitol exceeds that of 2. The first representative of a new class of organoselenium bicyclic compounds, 7,8-dimethoxy-9-selenabicyclo[4.2.1]nonane, was prepared by the iodine-mediated reaction of elemental selenium and 1,3-cyclooctadiene. Comparative kinetics of the oxidation of 7,8-dimethoxy-9-selenabicyclo[4.2.1]nonane 1 and its isomer 2,6-dimethoxy-9-selenabicyclo[3.3.1]nonane 2 were studied by 1H NMR spectroscopy and found to be dozens of times faster for the former. The catalytic activity of 7,8-dimethoxy-9-selenabicyclo[4.2.1]nonane 9-oxide formed in situ from 1 and simulating the GPx-like activity in oxidation of thiols by H 2 O 2 in MeOH, is shown to be higher than that of the isomeric 2,6-dimethoxy-9-selenabicyclo[3.3.1]nonane 9-oxide. [Display omitted] [ABSTRACT FROM AUTHOR]

Selenium compounds have a checkered history. Originally considered to be highly toxic, the tide turned in the 20th century when selenium was discovered to be an essential trace element; indeed, selenium is the least abundant element on Earth to have a well-defined biological role. Despite this new-found importance, organoselenium compounds were largely curiosities because methods for their synthesis were cumbersome and unpleasant and often involved toxic reagents and/or hazardous procedures. This paper describes how work carried out in collaboration with Alwyn Davies in the late 1980s, aimed at acquiring Electron Spin Responance (ESR) spectra of selenophene radical anions and cations, led to the development of free-radical methods for the synthesis of numerous selenium-containing heterocycles, many of which showed interesting and useful biological properties. This journey ends with the development of selenium-containing carbohydrates (selenosugars) that exhibit unique skin-repair properties and the establishment of Seleno Therapeutics as a vehicle for the commercialization of these selenosugars. [ABSTRACT FROM AUTHOR]

Selenium polysaccharide is an organic selenium compound, which has attracted much attention because of its unique biological properties. In the current study, a new selenium polysaccharide (Se-SCP) was synthesised, and its structure and effects on non-enzymatic glycosylation in vivo were studied. The molecular weight of Se-SCP was 9.02 g/mol, and its molecule was mainly composed of Man, Gal, GluA, Ara, Glu, Fuc, Rha, GalA, and Xyl. Selenium was present both as C–O–Se and Se=O. Compared with non-selenised sweet corncob polysaccharide (SCP) treatment, the blood glucose level in mice decreased considerably after Se-SCP treatment. Additionally, it improved oral glucose tolerance (OGTT) and significantly reduced the production of advanced glycation end-products (AGEs) (P < 0.05), compared with the model group. In addition, Se-SCP exhibited a positive effect on the morphology of the pancreas and liver. The current study elucidated the physiological and pharmacological effects of selenium polysaccharides and provided a basis for future studies on selenium polysaccharides. [ABSTRACT FROM AUTHOR]

With the aim of designing new heteroorganic ligands capable of sensitizing the metal-centered photoluminescence (PL) of YbIII through the redox mechanism, a new diselenide, 2,2′-(diseleno-2,1-diphenylene)bis[benzothiazole] ((SeSN)2, 1), was synthesized and structurally characterized. The selenophenolate complexes Na(SeSN)(DME)2(2) and Yb(SeSN)3·0.5 THF (3) were synthesized by the reactions of diselenide 1 with Na and Yb metals in liquid ammonia. Complex 2 showed intense PL at 77 K in a DME solution, which appears as a broad band with a maximum at 575 nm assigned to the phosphorescence of the organoselenide ligand. In the crystalline state, ytterbium complex 3, which was isolated and structurally characterized as an adduct with THF, exhibited intense metal-centered PL in the 980–1100 nm region. This PL is observed upon direct excitation or upon excitation through SeSN ligands (250–380 nm), as well as through excitation of the ligand-to-metal charge transfer (LMCT) band in the 430–700 nm region. The presence of low-energy LMCT states capable of sensitizing the metal-centered PL of YbIII in complexes with organoselenide ligands is responsible for a significant reduction of the Stokes shift of luminescence and opens up new prospects for the development of lanthanide-containing infrared luminophores exhibiting luminescence under long-wavelength excitation. [ABSTRACT FROM AUTHOR]

The deficiency of selenium has been found in clinical IBD patients and supplementation selenium is recognized as beneficial for colitis treatment. In this study, an organic selenium compound—selenylation α-D-1,6-glucan (sCPA) was prepared, and the effect of sCPA on DSS induced colitis mice was investigated. The results suggested that sCPA prevented the weight loss, colon length shortening, and stool loose of colitis mice. It protected colon mucosal barrier by promoting tight junction protein ZO-1 and Occludin expression. Moreover, sCPA reduced oxidative stress via regulating SOD and MDA levels, and decreased the contents of inflammatory proteins NF-κB and NLRP3 and adjusted TNF-α, IFN-γ, IL-1β, and IL-10 inflammatory cytokines. Furthermore, sCPA repaired intestinal microbiota composition especially Bacteroidetes, Firmicutes, Proteobacteria, and Actinobacteria that altered by DSS in colitis mice. Meanwhile, SCFAs produced by gut microbiota were restored by sCPA close to the level in the normal group. In conclusion, these findings indicated that the sCPA might be a potential dietary selenium supplementation for the prevention and treatment of colitis. [ABSTRACT FROM AUTHOR]

Copper (II) complexes (3a-i) with (16E)-N-(2-phenylquinolin-4(1H)-ylidine)-2-(phenylselanyl) benzenamine ligands were synthesized. They were characterized by various spectroscopic studies. In-vitro cytotoxic potential was determined, with significant cytotoxicity against MCF-7 cell line. The copper complexes interacted with the calf thymus - DNA, (CT-DNA), according to absorption spectra and viscosity measurements. In addition, the copper complexes were tested for antimicrobial activity against three Gram-negative bacteria; Proteus vulgaris, Klebsiella pneumoniae, and Shigella flexneri, three Gram-positive bacteria; Staphylococcus aureus, Staphylococcus epidermidis, and Bacillus subtilis, and three fungi; Aspergillus fumigatus, Aspergillus clavatus and Candida albicans. The ligand's acetylcholinesterase (AChE) inhibiting function was investigated in order to determine the ligand's efficacy in the treatment of neurodegenerative disorders. When compared to standard Rivastigmine and Galantamine, the synthesized ligand 2c showed selective inhibition (AChE & BuChE) with IC50 values of 0.20 and 3.03M. The egg albumin method was used to test the anti-inflammatory efficiency and a-glucosidase inhibitory activities of copper chelates were tested. [ABSTRACT FROM AUTHOR]

A novel intermolecular radical addition/cyclization and Se‐group transfer reaction of terminal alkynes and unsaturated alkyl selenide is presented which offers a straightforward and facile approach for the synthesis of valuable Se‐containing cyclopentenes. Remarkable features of this strategy include easily accessible starting materials, metal‐free and peroxide‐free conditions, high atom economy, simple operation and broad substrate scope. More importantly, the reaction is easy to scale up and can be extended to the construction of six‐membered carbon ring. [ABSTRACT FROM AUTHOR]

Isoselenazolone derivatives have attracted significant research interest because of their potent therapeutic activities and indispensable applications in organic synthesis. Efficient construction of functionalized isoselenazolone scaffolds is still challenging, and thus new synthetic approaches with improved operational simplicity have been of particular interest. In this manuscript, we introduce a rhodium‐catalyzed direct selenium annulation by using stable and tractable elemental selenium. A series of benzamides as well as acrylamides were successfully coupled with selenium under mild reaction conditions, and the obtained isoselenazolones could be pivotal synthetic precursors for several organoselenium compounds. Based on the designed control experiments and X‐ray absorption spectroscopy measurements, we propose an unprecedented selenation mechanism involving a highly electrophilic Se(IV) species as the reactive selenium donor. The reaction mechanism was further verified by a computational study. [ABSTRACT FROM AUTHOR]

In the recent decade, growing efforts have been devoted to employing elemental selenium as a selenium source in organic synthesis. In contrast to unstable, smelly, and toxic previous selenium reagents, elemental selenium is readily available, cheap, bench‐stable, and easy to handle. This review will mainly focus on the strategies for the activation of elemental selenium and the synthesis of organoselenium compounds including monoselenides, diselenides, selenium‐containing heterocycles and so on. [ABSTRACT FROM AUTHOR]

The synthesis and the study of organoselenium compounds have received much attention over the past decades. Selenium‐containing organic molecules are widely used in organic synthesis, materials science, and medicinal chemistry. Selenium – and more specifically the amino acid selenocysteine, bearing a selenol (SeH) moiety – is present in at least 25 human protein families, whose biological functions have not been completely identified. Amongst the variety of organoselenium compounds, selenols are a versatile class of molecules easily undergoing a broad array of useful transformations. Because of the unique properties of the SeH group, selenol chemistry has important applications in chemical sciences, spanning from organic synthesis to materials chemistry and biology. This review summarises currently available methodologies for the synthesis of selenols and highlights applications of selenols in chemical sciences and biology. [ABSTRACT FROM AUTHOR]

The derivatization of chitosan (CS) is widely exploited to endow this polysaccharide with enhanced physicochemical and biological properties. Beyond the synthetic route, the nature of the compounds used to functionalize the CS-derivatives exerts a pivotal role in their final properties. Making use of a simple "click" reaction, we synthesized for the first time an organoselenium-CS derivative through a 1,2,3-triazole formation. The product (CS-TSe) was characterized in detail by FTIR, NMR (1H, 13C, and 77Se) and UV–Vis techniques, and SEM microscopy. The antioxidant activity of CS-TSe was examined by ABTS+ and DPPH (free radical-scavenging) assays. Experimentally, it was demonstrated that CS-TSe has superior antioxidant activity compared with raw CS and "free" organoselenium compound, suggesting a benign and synergistic effect due to the derivatization. In short, the antioxidant property of CS-TSe combined with the other attractive properties of CS and selenium could be useful in the formulation of advanced materials for biomedical and packaging applications. [Display omitted] • A simple "click" reaction was used to synthesize an organoselenium-chitosan derivative. • The organoselenium compound was grafted to chitosan through a 1,2,3-triazole formation. • The derivative showed superior antioxidant activity compared to the precursor compounds. • The association of chitosan and Se benefits the radical scavenging ability of the derivative. • The chitosan derivative has a great prospect in the formulation of advanced materials. [ABSTRACT FROM AUTHOR]

The selenoenzyme glutathione peroxidase (GPx) like activity of stable organoselenium compounds has been evaluated through the initial rate (ν 0) of the reduction reaction of H2O2, Cum-OOH, and t-BuOOH. A Quantitative Structure–Activity Relationships (QSAR) analysis based on different machine learning techniques was performed by employing atom-weighed algebraic maps indexes as descriptors. The predictive capability of the obtained models was statistically validated by mean of the correlation coefficient for adjusting (R2), leave one out cross validation (Q2LOO), and bootstrapping (Q2boot). For the case of H2O2 reduction, a model was obtained with six attributes (M2) and values of R2 = 0.907, Q2LOO = 0.867, and Q2boot = 0.852. For the cum-OOH reduction, a model was obtained with five attributes (M15) with the statistical parameters: R2 = 0.925, Q2LOO = 0.894, and Q2boot = 0.873. For the t-BuOOH reduction, a model with four descriptors (M19) was found with the values of R2 = 0.938, Q2LOO = 0.897, Q2boot = 0.856. The statistical parameters obtained for these three models suggest that they are robust enough with good predictive capability. Finally, screening analysis of some related compounds containing selenium was performed and two possible lead compounds were found (16 and 53), which can be used for the searching of candidates with GPx-like activity. [ABSTRACT FROM AUTHOR]

Organoselenium compounds are potentially active substances. Herein, a novel method for the synthesis of 2‐substituted 3‐selanylbenzo[b]furans that uses Cu‐catalyzed C−H selenation, an efficient method for chemically transforming aromatic heterocycles, is described. The reactions of 2‐substituted benzo[b]furans with diaryl diselenides in the presence of 10 mol% copper iodide (CuI) at 120 °C in dimethyl sulfoxide (DMSO) afforded the corresponding 2‐substituted 3‐selanylbenzo[b]furans in moderate‐to‐excellent yields. The reaction proceeds efficiently and both of the two selanyl groups of the diselenide are transferred to the coupling products. [ABSTRACT FROM AUTHOR]

Ebselen is a low-molecular-weight organoselenium compound that has been broadly studied for its antioxidant, anti-inflammatory, and cytoprotective properties. These advantageous properties were initially associated with mimicking the activity of selenoprotein glutathione peroxidase, but the biomedical impact of this compound appear to be far more complex. Ebselen serves as a substrate or inhibitor with multiple protein/enzyme targets, whereas inhibition typically originates from the covalent modification of cysteine residues by opening the benzisoselenazolone ring and S–Se bond formation. The inhibition of enzymes of various classes and origins has been associated with substantial antimicrobial potential among other activities. In this contribution, we summarize the current state of the art regarding the antibacterial activity of ebselen. This activity, alone and in combination with commercial pharmaceuticals, against pathogens, including those resistant to drugs, is presented, together with the molecular mechanism behind the reactivity. The specific inactivation of thioredoxin reductase, bacterial toxins, and other resistance factors is considered to have certain therapeutic implications. Synergistic action and sensitization to common antibiotics assisted with the use of ebselen appear to be promising directions in the treatment of persistent infections.

Mitochondrial dysfunction is an early pathological feature of Alzheimer disease and plays a crucial role in the development and progression of Alzheimer's disease. Strategies to rescue mitochondrial function and cognition remain to be explored. Cyclophilin D (CypD), the peptidylprolyl isomerase F (PPIase), is a key component in opening the mitochondrial membrane permeability transition pore, leading to mitochondrial dysfunction and cell death. Blocking membrane permeability transition pore opening by inhibiting CypD activity is a promising therapeutic approach for Alzheimer's disease. However, there is currently no effective CypD inhibitor for Alzheimer's disease, with previous candidates demonstrating high toxicity, poor ability to cross the blood-brain barrier, compromised biocompatibility and low selectivity. Here, we report a new class of non-toxic and biocompatible CypD inhibitor, ebselen, using a conventional PPIase assay to screen a library of ∼2000 FDA-approved drugs with crystallographic analysis of the CypD-ebselen crystal structure (PDB code: 8EJX). More importantly, we assessed the effects of genetic and pharmacological blockade of CypD on Alzheimer's disease mitochondrial and glycolytic bioenergetics in Alzheimer's disease-derived mitochondrial cybrid cells, an ex vivo human sporadic Alzheimer's disease mitochondrial model, and on synaptic function, inflammatory response and learning and memory in Alzheimer's disease mouse models. Inhibition of CypD by ebselen protects against sporadic Alzheimer's disease- and amyloid-β-induced mitochondrial and glycolytic perturbation, synaptic and cognitive dysfunction, together with suppressing neuroinflammation in the brain of Alzheimer's disease mouse models, which is linked to CypD-related membrane permeability transition pore formation. Thus, CypD inhibitors have the potential to slow the progression of neurodegenerative diseases, including Alzheimer's disease, by boosting mitochondrial bioenergetics and improving synaptic and cognitive function., (© The Author(s) 2023. Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

A new electrophilic selenocyanation reagent N -seleno-cyanato-dibenzenesulfonimide was readily prepared in two steps from commercially available dibenzenesulfonimide for the first time. A variety of electrophilic selenocyanato reactions of nucleophiles have been achieved using it as selenocyanato source under mild and simple conditions. Numerous SeCN-containing compounds were obtained in moderate to excellent yields. Meanwhile, a Lewis acid mediated tandem selenocyanation/cyclization reaction of alkenes with phenols, which provided simple methods for the formation of various SeCN-containing chromanes and dihydrobenzofurans in moderate to good yields, has also been developed. [ABSTRACT FROM AUTHOR]

Organoselenium compounds find versatile applications in organic synthesis, materials synthesis, and ligand chemistry. Organoselenium heterocycles are widely studied agents with diverse applications in various biological processes. This review highlights the recent progress in the synthesis of selenium heterocycles using diorganyl diselenides with keen attention on green synthetic approaches, scopes, C–H selanylation, the mechanisms of different reactions and insights into the formation of metal complexes. The C–H selanylation using diorganyl diselenides with different catalysts, bases, transition metals, iodine salts, NIS, hypervalent iodine, and other reagents is summarised. Finally, the diverse binding modes of bis(2/4-pyridyl)diselenide with different metal complexes are also summarised. [ABSTRACT FROM AUTHOR]

Organoselenium compounds constitute an important class of substances with applications in the biological, medicinal and material sciences as well as in modern organic synthesis, attracting considerable attention from the scientific community. Therefore, the construction of the C−Se bond via facile, efficient and sustainable strategies to access complex scaffolds from simple substrates are an appealing and hot topic. Visible light can be regarded as an alternative source of energy and is associated with environmentally‐friendly processes. Recently, the use of visible‐light mediated seleno‐functionalization has emerged as an ideal and powerful route to obtain high‐value selenylated products, with diminished cost and waste. This approach, involving photo‐excited substrates/catalyst and single‐electron transfer (SET) between substrates in the presence of visible light has been successfully used in the versatile and direct insertion of organoselenium moieties in activated and unactivated C(sp3)−H, C(sp2)−H, C(sp)−H bonds as well as C−heteroatom bonds. In most cases, ease of operation and accessibility of the light source (LEDs or commercial CFL bulbs) makes this approach more attractive and sustainable than the traditional strategies. [ABSTRACT FROM AUTHOR]

For the efficient synthesis of transition-metal cobalt oxide nanoparticles (Co3O4 NPs) without using any costly and toxic solvent or complicated equipment, the co-precipitation method was used in this work. Using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), UV–Vis spectrophotometry, Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), the prepared Co3O4 NPs were characterized and identified. The influence of prepared Co3O4 NPs on the developmental synthesis of some selenopyridine/quinoline derivatives under different microwave irradiation powers and irradiation times was investigated via click (reaction) chemistry. The reusable Co3O4 nanoparticles have high catalytic activity under microwave irradiation for the synthesis of organoselenium compounds with higher yields (> 90%), milder reaction conditions and shorter time without significantly decreasing the reaction rates and yields. [ABSTRACT FROM AUTHOR]

We studied the effect of an experimental synthetic organoselenium compound 2,6-dipyridinium- 9-selenabicyclo[3.3.1]nonane dibromide (974zh) on the cell composition of the red bone marrow and peripheral blood in white mice. The study drug co-administered with Yersinia pestis EV vaccine strain (103 CFU) potentiated maturation and migration of mature neutrophils from the bone marrow into the circulation. Reducing the dose of the live vaccine and the anti-inflammatory properties of the study drug made it possible to reduce the allergic reaction during the vaccination process. [ABSTRACT FROM AUTHOR]

Antioxidant activity of organoselenium compounds belonging to different classes i.e. functionalized aliphatic, aromatic and cyclic selenoethers, are compared on the basis of their ability to scavenge reactive oxygen species like hydroxyl and peroxyl radicals and to exhibit glutathione peroxidase (GPx) like catalytic activity. The comparative analysis has revealed that the antioxidant activity of the organoselenium compounds show direct correlation with the energy of the highest occupied molecular orbital (HOMO) and neighboring group participation that stabilizes the reaction intermediate. Finally, structural features responsible for improving the rate of reaction of organoselenium compounds with free radical/molecular oxidants have been discussed on the basis of the compounds screened at our institute. [ABSTRACT FROM AUTHOR]

A Rh(III)-catalyzed C-H functionalization approach was developed for the preparation of multisubstituted 3-fluoropyridines from α-fluoro-α,β-unsaturated oximes and alkynes. Oximes substituted with aryl, heteroaryl, and alkyl β-substituents were effective coupling partners, as were symmetrical and unsymmetrical alkynes with aryl and alkyl substituents. The first examples of coupling α,β-unsaturated oximes with terminal alkynes was also demonstrated and proceeded with uniformly high regioselectivity to provide single 3-fluoropyridine regioisomers. Reactions were also conveniently set up in air on the benchtop.

A mild, practical, metal and oxidant-free methodology for the synthesis of various C-3 selenylated benzo[b]furan derivatives was developed through the intramolecular cyclization of alkynes promoted with diselenides via electrooxidation. A wide range of selenium-substituted benzo[b]furan derivatives were obtained in good to excellent yields with high regioselectivity under constant current in an undivided cell equipped with carbon and platinum plates as the anode and cathode, respectively. Moreover, the convergent approach exhibited good functional group tolerance and could be easily scaled up with good efficiency, providing rapid access to a diverse range of selenylated benzo[b]furans derivatives from simple, readily available starting materials.

Organoselenium ligands have attracted great attention among researchers during the past two decades. Various homogeneous, heterogeneous and nanocatalytic systems have been designed using such ligands. Although reports on selenium ligated homogeneous catalysts are quite high in number, significant work has also been done on the development of heterogeneous and nanocatalytic systems using organoselenium ligands. A review article, focusing on the utility of organoselenium compounds in the development of catalytic systems, was published in 2012 (A. Kumar, G. K. Rao, F. Saleem and A. K. Singh, Dalton Trans., 2012, 41, 11949). Moreover, it mainly covered the homogeneous catalysts. There are no review articles in the literature on heterogeneous and nanocatalytic systems designed using organoselenium compounds and their applications. Hence, this perspective aims to cover the developments pertaining to the synthetic aspects of such catalytic systems (using organoselenium compounds) and their applications in catalysis of a variety of chemical transformations. Salient features and advantages of organoselenium compounds have also been highlighted to justify the rationale behind their use in catalyst development. Their performance in various chemical transformations [viz. Suzuki–Miyaura coupling, Heck coupling, Sonogashira coupling, O-arylation of phenol, transfer hydrogenation of aldehydes and ketones, aldehyde–alkyne–amine (A3) coupling, hydration of nitriles, conversion of aldehydes to amides, cross-dehydrogenative coupling (CDC), photodegradation of substrates (formic acid, methylene blue), reduction of nitrophenols, electrolysis (hydrogen evolution reaction and oxygen reduction reactions), organocatalysis and dye sensitized solar cells] and relevant aspects of catalytic processes (such as recyclability, substrate scope and green aspects) have been critically analyzed. Future perspectives have also been discussed. [ABSTRACT FROM AUTHOR]

Invasive aspergillosis is one of the major causes of morbidity and mortality among invasive fungal infections. The search for new antifungal drugs becomes imperative when existing drugs are not able to efficiently treat these infections. Ebselen, is an organoselenium compound, already successfully approved in clinical trials as a repositioned drug for the treatment of bipolar disorder and prevention of noise-induced hearing loss. In this study, we aimed to reposition ebselen for the treatment of invasive aspergillosis by showing ebselen effectiveness in a murine model. For this, BALB/c mice were immunosuppressed and infected systemically with Aspergillus fumigatus. Animals were divided and treated with ebselen, voriconazole, or drug-free control, for four days. The kidneys were used for CFU count and, histopathological and cytokine analysis. Ebselen was able to significantly reduce the fungal burden in the kidneys of infected mice with efficacy comparable with voriconazole treatment as both had reductions to the same extent. The absence of hyphae and intact kidney tissue structure observed in the histopathological sections analyzed from treated groups corroborate with the downregulation of IL-6 and TNF. In summary, this study brings for the first time in vivo evidence of ebselen efficacy against invasive aspergillosis. Despite these promising results, more animal studies are warranted to evaluate the potential role of ebselen as an alternative option for the management of invasive aspergillosis in humans. [ABSTRACT FROM AUTHOR]

Isoselenocyanates (ISCs) are a class of organoselenium compounds that have been recognized as potential chemotherapeutic and chemopreventative agents against cancer(s) and infectious diseases. ISC compounds are chemically analogous to their isosteric relatives, isothiocyanates (ITCs); however, they possess increased biological activity, such as enhanced cytotoxicity against cancer cells. ISCs not only serve as significant products, but also as precursors and essential intermediates for a variety of organoselenium compounds, such as selenium-containing heterocycles, which are biologically active. While syntheses of ISCs have become less difficult to accomplish, the syntheses of selenium-containing heterocycles are often difficult due to the use of highly toxic selenium reagents. Because of this, ISCs can serve as versatile reagents for the preparation of these heterocycles. In this review, the classical and recent syntheses of ISCs will be discussed, along with notable and recent synthetic work employing ISCs to access novel selenium-containing heterocycles. 1 Introduction 1.1 Selenium and Health 2 Isoselenocyanates 2.1 Preparation of Isoselenocyanates 3 Selenium-Containing Heterocycles 3.1 Notable Synthetic Work 3.2 Recent Synthetic Work 3.2.1 Synthesis of N -(3-Methyl-4-phenyl-3 H -selenazol-2-ylidene)benzamide- Derivatives 3.2.2 Synthesis and X-ray Studies of Diverse Selenourea Derivatives 3.2.3 Synthesis of Heteroarene-Fused [1,2,4]Thiadiazoles/Selenadiazoles via Iodine-Promoted [3+2] Oxidative Cyclization 3.2.4 2-Amino-1,3-selenazole Derivatives via Base-Promoted Multicomponent Reactions 4 Conclusion [ABSTRACT FROM AUTHOR]

In light of this, we used 1 mmol of acyl chloride, 1 mmol of potassium selenocyanate, and 1 mmol of 2-aminobenzimidazole in dry acetone at room temperature for the rest of our reactions. General procedure for the synthesis of compounds 4 To a stirred solution of potassium selenocyanate ( B 3 b , 0.144 g, 1 mmol) in dry acetone (3 mL), a solution of acyl chloride ( B 2 b , 1 mmol) in dry acetone (3 mL) was added at room temperature. Initially, the reaction among benzoyl chloride, potassium selenocyanate, and 2-aminobenzimidazole was selected as the model reaction for the preparation of compound B 4a b (Ar = Ph). In recent years, increasing attention has been paid to organoselenium compounds because of their diverse pharmaceutical and synthetic applications.[[1]] For example, acyl isoselenocyanates are useful reactive intermediates, and they have been prepared by the reaction of acyl chlorides with KSeCN.[[12]] The acyl isoselenocyanates, however, were never isolated.[[15]] The existence of these intermediates was inferred by their reactions with nucleophiles.[[19]] With this in mind, we now report on the use of such acyl isoselenocyanates, generated I in situ i , to prepare novel 1,3,5-triazine-2-selenones (Scheme 1, compounds B 4 b ). [Extracted from the article]

Fungal infections are one of the most prevalent diseases in the world and there is a lack of new antifungal drug development for these diseases. We conducted a systematic review of the literature regarding the in vitro antifungal activity of the organoselenium compounds ebselen (Eb) and diphenyl diselenide [(PhSe)2]. A systematic review was carried out based on the search for articles with data concerning Minimal Inhibitory Concentration (MIC) values, indexed in international databases and published until August 2020. A total of 2337 articles were found, and, according to the inclusion and exclusion criteria used, 22 articles were included in the study. Inhibitory activity against 96% (200/208) and 95% (312/328) of the pathogenic fungi tested was described for Eb and [(PhSe)2], respectively. Including in these 536 fungal isolates tested, organoselenium activity was highlighted against Candida spp. Cryptococcus ssp. Trichosporon spp. Aspergillus spp. Fusarium spp. Pythium spp. and Sporothrix spp. with MIC values lower than 64 μg/mL. In conclusion, Eb and [(PhSe)2] have a broad spectrum of in vitro inhibitory antifungal activity. These data added with other pharmacological properties of these organoselenium compounds suggest that both compounds are potential future antifungal drugs. Whether MICs toward the upper end of the ranges described here are compatible with efficacious therapy, and whether they may achieve such end as a result of the favorable non-antimicrobial effects of selenium on the host, requires more in vivo testing. [ABSTRACT FROM AUTHOR]

Pain has a negative impact on public health, reducing quality of life. Unfortunately, current treatments are not fully effective and have adverse effects. Therefore, there is a need to develop new analgesic compounds. Due to promising results regarding the antinociceptive effect of N-(3-(phenylselanyl)prop-2-in-1-yl)benzamide (SePB), this study aimed to evaluate the participation of the dopaminergic and noradrenergic systems in this effect in mice, as well as its toxicity. To this, the antagonists sulpiride (D 2 /D 3 receptor antagonist, 5 mg/kg), SCH-23390 (D 1 receptor antagonist, 0.05 mg/kg), prazosin (α 1 adrenergic receptor antagonist, 0.15 mg/kg), yohimbine (α 2 -adrenergic receptors, 0.15 mg/kg) and propranolol (non-selective β-adrenergic antagonist, 10 mg/kg) were administered intraperitoneally to mice 15 min before SePB (10 mg/kg, intragastrically), except for propranolol (20 min). After 26 min of SePB administration, the open field test was performed for 4 min to assess locomotor activity, followed by the tail immersion test to measure the nociceptive response. For the toxicity test, animals received a high dose of 300 mg/kg of SePB. SePB showed an increase in the latency for nociceptive response in the tail immersion test, and this effect was prevented by SCH-23390, yohimbine and propranolol, indicating the involvement of D 1 , α 2 and β-adrenergic receptors in the antinociceptive mechanism of the SePB effect. No changes were observed in the open field test, and the toxicity assessment suggested that SePB has low potential to induce toxicity. These findings contribute to understanding SePB's mechanism of action, with a focus on the development of new alternatives for pain treatment. [Display omitted] • SePB is an organoselenium compound with antinociceptive effect. • The antinociceptive effect of SePB depends on dopaminergic and noradrenergic systems. • D 1 , α 2 , and β receptors are involved with the antinociceptive effect of SePB. • SePB has low toxicity potential. [ABSTRACT FROM AUTHOR]