(p-ClPhSe)2 modulation on carbohydrate and lipid metabolism requires the insulin-like signaling in Caenorhabditis elegans.

Organoselenium compounds modulate the metabolism by regulating carbohydrate and lipid syntheses and degradation in the liver, muscle, and adipose tissue. Notably, p-chloro-diphenyl diselenide (p-ClPhSe)2 can directly regulate the activities of enzymes involved in glucose metabolism, suggesting an insulin-like effect in rodents; however, there is still a lack of scientific evidence to confirm this hypothesis. The objective of this study was to investigate (p-ClPhSe)2 effects on glucose and lipid metabolism in Caenorhabditis elegans. The contribution of AGE-1/PI3K, AKT-1, AKT-2, PFK-1, DAF-16, and DAF-2 in the (p-ClPhSe)2 effects were also investigated. Our results demonstrate that (p-ClPhSe)2 acute exposure presented some toxicity to the worms, and therefore, lower concentrations were further used. (p-ClPhSe)2 reduced glucose and triglyceride levels to the baseline levels, after induction with glucose or fructose, in wild-type worms. This effect required proteins involved in the insulin/IGF-1 like signaling, such as the DAF-2, AGE-1, AKT-1 and AKT-2, PFK-1, but also DAF-16, which would be negatively regulated by DAF-2 activation. Moreover, the reduction in glucose and triglyceride levels, caused by (p-ClPhSe)2per se was lost in age-1/daf-16 worms, suggesting that insulin/IGF-1-like signaling in a DAF-2 and AGE-1/DAF-16 dependent-manner in C. elegans are necessary to effects of (p-ClPhSe)2. In conclusion, (p-ClPhSe)2 requires proteins involved in the IIS pathway to modulate carbohydrate and lipid metabolism.

Recent Progress in Synthetic and Biological Application of Diorganyl Diselenides.

Diorganyl diselenides have emerged as privileged structures because they are easy to prepare, have distinct reactivity, and have broad biological activity. They have also been used in the synthesis of natural products as an electrophile in the organoselenylation of aromatic systems and peptides, reductions of alkenes, and nucleophilic substitution. This review summarizes the advancements in methods for the transformations promoted by diorganyl diselenides in the main functions of organic chemistry. Parallel, it will also describe the main findings on pharmacology and toxicology of diorganyl diselenides, emphasizing anti-inflammatory, hypoglycemic, chemotherapeutic, and antimicrobial activities. Therefore, an examination detailing the reactivity and biological characteristics of diorganyl diselenides provides valuable insights for academic researchers and industrial professionals.

Electrophile-Promoted Nucleophilic Cyclization of 2-Alkynylindoles to Give 4-Substituted Oxazinoindolones.

A method for the synthesis of 4-organoselanyl oxazinoindolone derivatives by the cascade cyclization of N-(alkoxycarbonyl)-2-alkynylindoles using iron(III) chloride and diorganyl diselenides as promoters was developed. This protocol was applied to a series of N-(alkoxycarbonyl)-2-alkynylindoles containing different substituents. The reaction conditions also tolerated a variety of diorganyl diselenides having both electron donating and electron withdrawing groups. However, the reaction did not work for diorganyl disulfides and ditellurides. The reaction mechanism seems to proceed via an ionic pathway and the cooperative action between iron(III) chloride and diorganyl diselenides is crucial for successful cyclization. We also found that using the same starting materials, by simply changing the electrophilic source to iodine, led to the formation of 4-iodo-oxazinoindolones. The high reactivity of Csp2 -Se and Csp2 -I bonds were tested under cross-coupling conditions leading to the preparation of a new class of functionalized indole derivatives. In addition, the absorption, emission and electrochemical properties of 4-organoselanyl oxazinoindolones showed an important relationship with the substituents of the aromatic rings. The advantages of the methodology include the use of electrophilic to promote the cyclization reaction and functionalization of the indole ring, and the electronic properties presented by the prepared compounds can be exploited as probes, analyte detectors and optical materials.

Effectiveness of diphenyl diselenide against experimental sporotrichosis caused by Sporothrix brasiliensis.

Diphenyl diselenide (PhSe)2 is a stable organoselenium compound with promising in vitro antifungal activity against several fungi, including Sporothrix brasiliensis. This species is associated with feline and zoonotic sporotrichosis, an emergent mycosis in Latin America. We evaluated the activity of (PhSe)2, alone and in association with itraconazole, in the treatment of sporotrichosis caused by S. brasiliensis, in a murine model. Sixty mice were subcutaneously infected with S. brasiliensis in the footpad and treated by gavage for 30 consecutive days. The six treatment groups received: no active treatment, itraconazole (50 mg/kg), (PhSe)2 at 1, 5, and 10 mg/kg dosages, or itraconazole (50 mg/kg) + (PhSe)2 1 mg/kg, once a day, starting seven days post-inoculation. A significant reduction in the fungal burden of internal organs was achieved in the groups treated with (PhSe)2 1 mg/kg or itraconazole alone in comparison with the untreated group. Higher dosages (5 and 10 mg/kg) of (PhSe)2 increased the clinical manifestation of sporotrichosis and mortality rate. Treatment with both itraconazole and (PhSe)2 1 mg/kg was better than their activities alone (P < .001). This is the first demonstration of the potential use of (PhSe)2, alone or with the present drug of choice, in the treatment of sporotrichosis.

We evaluated the activity of diphenyl diselenide (PhSe)2, alone and in association with itraconazole, in the treatment of sporotrichosis caused by S. brasiliensis, in a murine model. This is the first demonstration of the potential use of (PhSe)2, alone or in an association against sporotrichosis.

Palladium-Catalyzed Cascade 5-endo-dig Cyclization of Ynamides to Form 4-Alkynyloxazolones.

The selective synthesis of 4-alkynyloxazolones and their further applications as substrates to electrophile-promoted nucleophilic cyclization have been developed. The reaction of ynamides with terminal alkynes proceeded smoothly to give 4-alkynyloxazolones in the presence of a catalytic amount of palladium(II) acetate. The products were obtained with the sequential formation of new C-C and C-O bonds via a cascade procedure. The first step involved a carbon-oxygen bond formation, via a 5-endo-dig closure, which was confirmed by X-ray analyses of the crystalline sample. Subsequently, the reaction of 4-alkynyloxazolones with an electrophilic selenium source gave 3-phenylselanyl benzofuran derivatives via an electrophile-promoted nucleophilic cyclization.

Potassium tert-Butoxide-Promoted Tandem Cyclization of Organoselenium Alkynyl Aryl Propargyl Ethers.

Base-promoted cyclization of 3-organoselenyl-methylene-2-alkynyl aryl propargyl ethers has been developed for the synthesis of 3-butylselanyl-methylene benzofurans, 3-methyl-2-alkynyl-benzofurans, and 4-iodo-benzo[b]furan-fused selenopyrans. Under potassium tert-butoxide as the base and tetrahydrofuran as the solvent, at room temperature, 3-organoselenyl-methylene-2-alkynyl aryl propargyl ethers were converted into 3-butylselanyl-methylene benzofurans via a 5-exo-dig mode. Using the same substrate, changing the solvent to dimethylsulfoxide, 3-methyl-2-alkynyl-benzofurans were selectively obtained in good yields. From 3-butylselanyl-methylene benzofurans, 4-iodo-benzo[b]furan-fused selenopyrans were prepared through a nucleophilic cyclization promoted by molecular iodine. The optimization of the reaction conditions showed that the solvents governed the regioselectivity of this cyclization and the initial formation of the dimsyl anion by the reaction of dimethylsulfoxide with potassium tert-butoxide was crucial for the 3-methyl-2-alkynyl-benzofuran preparation. We also proposed the mechanism for the formation of the products, demonstrated that the methodology can be scaled up, and showed the application of the prepared compounds as substrate in further transformations.

Stereoselective Reduction of Alkynes: Synthesis of 4-Organoselenyl Quinolines.

This study describes the reaction of 2-amino arylalkynyl ketones with organoselenolates to form (Z)-vinyl selenides, which lead to 4-organoselenyl quinolines via an intramolecular condensation. Using the optimized reaction conditions, the generality of this cyclization was studied with various arylalkynyl ketones and diorganyl diselenides. The study of the reaction mechanisms led to the isolation and identification of a vinyl selenide, which was the key intermediate for this cyclization. To expand the structural diversity and to demonstrate the applicability of the 4-organoselenyl quinolines prepared, we studied their application as substrates in the cleavage of the carbon-selenium bond using n-butyllithium followed by the capture of the lithium intermediate by electrophiles and Suzuki and Sonogashira cross-coupling reactions.

Synthesis of 4-(organoselenyl) oxazolones via cyclization of N-alkynyl ethylcarbamates promoted by organoselenium.

Organoselenyl iodide promoted the intramolecular nucleophilic cyclization of N-alkynyl ethylcarbamates in the synthesis of 4-(organoselenyl) oxazolones. The reaction was regioselective, giving the five-membered oxazolone products as the unique regioisomer via an initial activation of the carbon-carbon triple bond through a seleniranium intermediate, followed by an intramolecular 5-endo-dig cyclization mode. The generality of the methodology has been proven by applying the optimized reaction conditions to different organoselenyl iodides and N-alkynyl ethylcarbamates having different substituents directly bonded to the nitrogen atom and in the terminal position of the alkyne.

Transition Metal-Free Synthesis of Carbo- and Heterocycles via Reaction of Alkynes with Organylchalcogenides.

This manuscript intends to overview the most recent advances in the synthesis of carbo- and heterocycles through reactions of alkynes with organyl chalcogenides (S, Se, Te) under metal-free conditions. Firstly, the use of electrophilic chalcogenyl halides as a selective reagent for alkyne carbon-carbon triple bond activation will be presented. After that, radical cyclization protocols employing electrochemical oxidative conditions, light-induced photoredox catalysis, or mild oxidants with direct chalcogenyl group installation will be discussed accompanied by the proposed mechanisms.

Diorganyl Diselenides and Iron(III) Chloride Drive the Regio- and Stereoselectivity in the Selenation of Ynamides.

We report here our results on the application of ynamides as substrates in the reactions with diorganyl dichalcogenides and iron(III) chloride to give selectively three different types of compounds: E-α-chloro-ß-(organoselenyl)enamides, 4-(organochalcogenyl)oxazolones, and vinyl tosylates. The results reveal that the selectivity in the formation of products was obtained by controlling the functional groups directly bonded to the nitrogen atom of the ynamides. Thus, α-chloro-ß-(organoselenyl) enamide derivatives were exclusively obtained when the TsN- and MsN-ynamides were treated with a mixture of diorganyl diselenides (1.0 equiv) and FeCl3 (3.0 equiv) in dichloroethane (DCE, 3 mL), at room temperature. The 4-(organochalcogenyl)oxazolones were selectively obtained with ynamides having an ester group, directly bonded to the nitrogen atom, upon treatment with a solution of FeCl3 (1.5 equiv) and diorganyl dichalcogenides (1.0 equiv) in dichloromethane (3 mL) at room temperature. Finally, vinyl tosylates were obtained from ynamides having an ester group, directly bonded to the nitrogen atom, by reaction with p-toluenesulfonic acid. We also studied the application of the prepared compounds as substrates for Suzuki and Sonogashira cross-coupling reactions.

Synergism of Nikkomycin Z in Combination with Diphenyl Diselenide Against Sporothrix spp.

We evaluated the in vitro activity of nikkomycin Z (NikZ) in combination with diphenyl diselenide (PhSe)2, two compounds previously shown to have anti-Sporothrix spp. activity. Eighteen isolates of Sporothrix spp. were tested in checkerboard assays. Synergism for inhibition and killing Sporothrix spp. occurred in 100% and 89% of the isolates, respectively. The anti-Sporothrix spp. activity of this combination provides a rationale for in vivo studies to evaluate the application of both compounds in sporotrichosis treatment.

Alkynes and Nitrogen Compounds: Useful Substrates for the Synthesis of Pyrazoles.

The easy preparation and functionalization of pyrazoles associated with their innumerable biological properties have made this class of N-heterocycles very attractive for the development of new synthetic routes and applications. The cyclization reactions of alkynes and nitrogen compounds represent a powerful tool for the preparation of pyrazoles. This Review covers the recent advances in the preparation of pyrazoles by reacting alkynes and nitrogen compounds under transition-metal-catalyzed or metal-free conditions.

Synthesis of Selenochromenes via Dehydration of Arylalkynols Promoted by Iron(III) Chloride and Diorganyl Diselenides.

We report here the regioselective 6-endo-dig cyclization of [2-(butylselanyl)phenyl]propynols promoted by the cooperative action between diorganyl diselenides and iron(III) chloride leading to the formation of 4-methylene-3-(organoselanyl)-selenochromenes. The results of the reaction condition optimization studies showed that the solvent, the iron source, and the amount of diorganyl diselenide had a fundamental influence on the reaction yields. In the presence of iron(III) chloride (1.5 equiv) and diorganyl diselenides (1.0 equiv), using dichloromethane as the solvent, at room temperature, 4-methylene-3-(organoselanyl)-selenochromenes were formed in moderate to good yields. The reaction conditions were found to be suitable for substrates bearing electron-donating and electron-withdrawing groups on the aromatic ring at both propargyl and alkyne positions. However, we observed a limitation in the reaction conditions when they were applied to other diorganyl dichalcogenides, such as diorganyl disulfides and diorganyl ditellurides, which did not give the corresponding products. We also elaborated on a mechanism proposal based on control experiments performed.

Diphenyl diselenide and its interaction with antifungals against Aspergillus spp.

Given the few antifungal classes available to treat aspergillosis, this study aimed to evaluate the in vitro antifungal activity of diphenyl diselenide (PhSe)2 alone and in combination with classical antifungals against Aspergillus spp., and its in vivo activity in a systemic experimental aspergillosis model. We performed in vitro broth microdilution assay of (PhSe)2 against 32 Aspergillus isolates; and a checkboard assay to test the interaction of this compound with itraconazole (ITC), voriconazole (VRC), amphotericin B (AMB), and caspofungin (CAS), against nine Aspergillus isolates. An experimental model of invasive aspergillosis in mice was studied, and survival curves were compared between an untreated group and groups treated with 100 mg/kg ITC, or (PhSe)2 in different dosages (10 mg/kg, 50 mg/kg and 100 mg/kg). All Aspergillus non-fumigatus and 50% of A. fumigatus were inhibited by (PhSe)2 in concentrations ≤ 64 µg/ml, with significant differences in MICs between the sections. Synergism or additive effect in the in vitro (PhSe)2 interaction with VRC and CAS was observed against the majority of isolates, and with ITC against the non-fumigatus strains. In addition to the inhibitory interaction, (PhSe)2 was able to add a fungicidal effect to CAS. Survival curves from the systemic experimental aspergillosis model demonstrated that the inoculum caused an acute and lethal infection in mice, and no treatment applied significantly prolonged survival over that of the control group. The results highlight the promising activity of (PhSe)2 against Aspergillus species, but more in vivo studies are needed to determine its potential applicability in aspergillosis treatment. LAY SUMMARY: The activity of diphenyl diselenide (PhSe)2 alone and in combination with itraconazole, voriconazole, and caspofungin, is described against three of the most pathogenic Aspergillus sections. (PhSe)2 may prove useful in therapy of infection in future; further study is required.

Synthesis of indoles from alkynes and a nitrogen source under metal-free conditions.

Indoles are an important nucleus of N-heterocycles found in many natural products, active pharmaceuticals, and functional materials. In addition, indoles have various reactive positions, each one with a different reactivity, which may be susceptible to different reactions. This characteristic makes them important substrates for further transformations. This paper deals with the methodologies published in the last ten years, which used metal-free conditions to prepare indoles starting from alkynes and nitrogen compounds.

Selenium-promoted electrophilic cyclization of arylpropiolamides: synthesis of 3-organoselenyl spiro[4,5]trienones.

This paper describes a selenium-promoted electrophilic cyclization of arylpropiolamides allowing the synthesis of 3-organoselenyl spiro[4,5]trienones via a 5-endo-dig ipso-mode. The 3-organoselenyl-quinolinone derivative formation via 6-endo-dig was avoided using an electrophilic organoselenium species in a metal-free protocol. The use of phenylselenyl bromide (1.3 equiv.), as the electrophilic source, in nitromethane (3 mL) at 90 °C enabled the cyclization of N-(2-methoxyphenyl)-N-methyl-3-phenylpropiolamides, giving 3-organoselenyl[4,5]triene-2,6-dione derivatives. The extension of the standard conditions to the N-(4-methoxyphenyl)-phenylpropiolamides led to the corresponding 3-organoselenyl spiro[4,5]trienones having the carbonyl group at the 8-position. Besides, we demonstrated a general application of our approach by using 3-organoselenyl spiro[4,5]trienones as substrates in Suzuki cross-coupling reactions, which gave the cross-coupled products in good yields.

Synthesis of 3-(Organochalcogen) Chalcogenazolo Indoles via Cascade Cyclization of N-Alkynylindoles.

A transition metal-free one-pot, three-steps protocol combining N-alkynylindoles, n-butyllithium, elemental selenium, and an electrophile source was developed to allow the synthesis of 3-(organoselanyl) selenazolo indoles. Substrate scope was studied by varying the structure of N-alkynylindoles and the electrophile source. This sequential reaction proceeded selectively through an initial intramolecular 5- endo-dig mode with two new carbon-selenium bonds formation in a one-pot procedure. The reaction conditions were also compatible with elemental sulfur and tellurium, which led to construct 3-(alkylthio) thiazolo indoles and 3-(alkyltelluro) tellurazolo indoles, respectively. In addition, it was also demonstrated that a series of dichalcogenides derived from chalcogenazoloindoles ring could be easily prepared via oxidation of chalcogenolate anion in contact with air.

Cyclization of Thiopropargyl Benzimidazoles by Combining Iron(III) Chloride and Diorganyl Diselenides.

A practical synthetic approach to the synthesis of 3-(organoselenyl)-imidazothiazines was developed. The methodology involved the regioselective 6-endo-dig cyclization of thiopropargyl benzimidazoles promoted by diorganyl diselenides and iron(III) chloride. The investigation to determine the best reaction conditions indicated the use of thiopropargyl benzimidazoles (0.25 mmol) with diorganyl diselenides (1.0 equiv) and iron(III) chloride (2.0 equiv) in dichloromethane at 40 °C for 30 min to be optimal. Under these conditions, the scope of the substrates was evaluated varying the structures of thiopropargyl benzimidazoles and diorganyl diselenides giving 28 3-(organoselenyl)-imidazothiazines in moderate to good yields. The reaction conditions were also applicable to diorganyl ditellurides; however, they did not work for diorganyl disulfides. The mechanism studies were carried out indicating that the cyclization proceeds via a cooperative action of diorganyl diselenides and iron(III) chloride, but a direct electrophilic cyclization, promoted by the in situ formed electrophilic organoselenium species, cannot be ruled out.

In vitro activity of diphenyl diselenide and ebselen alone and in combination with antifungal agents against Trichosporon asahii.

This study evaluated the in vitro susceptibility of Trichosporon asahii strains to diphenyl diselenide (DPDS) and ebselen (EBS) alone and in combination with amphotericin B (AMB), fluconazole (FCZ), itraconazole (ITZ) and caspofungin (CAS) using the microdilution method. EBS showed in vitro activity against T asahii strains with minimal inhibitory concentration (MIC) ranged from 0.25 to 8.0 µg/mL. For DPDS, the MIC ranged from 8.0 to 64 µg/mL. The combinations demonstrating the greatest synergism rate against fluconazole-resistant T asahii strains were the following: CAS + DPDS (96.67%), AMB + DPDS (93.33%), FCZ + DPDS (86.67%) and ITZ + DPDS (83.33%). The combinations AMB + DPDS and AMB + EBS exhibited the highest synergism rate against the fluconazole-susceptible (FS) T asahii strains (90%). Antagonism was observed in the following combinations: FCZ + EBS (80%) and FCZ + DPDS (13.33%) against the FS strains, and ITZ + EBS (20%) against the FR strains. Our findings suggest that the antimicrobial activity of DPDS and EBS against T. asahii and its use as an adjuvant therapy with antifungal agents warrant in vivo experimental investigation.

Ebselen inhibits the activity of acetylcholinesterase globular isoform G4 in vitro and attenuates scopolamine-induced amnesia in mice.

There is a well-known relationship between the cholinergic system and learning, memory, and other common cognitive processes. The process for researching and developing new drugs has lead researchers to repurpose older ones. This study investigated the effects of ebselen on the activity of acethylcholinesterase (AChE) isoforms in vitro and in an amnesia model induced by scopolamine in Swiss mice. In vitro, ebselen at concentrations equal or higher than 10 µM inhibited the activity of cortical and hippocampal G4/AChE, but not G1/AChE isoform. Treatment of mice with ebselen (50 mg/kg, i.p.) was effective against impairment of spatial recognition memory in both Y-maze and novel object recognition tests induced by scopolamine (1 mg/kg, i.p.). Ebselen (50 mg/kg) inhibited hippocampal AChE activity in mice. The present study demonstrates that ebselen inhibited the G4/AChE isoform in vitro and elicited an anti-amnesic effect in a mouse model induced by scopolamine. These findings reveal ebselen as a potential compound in terms of opening up valid therapeutic avenues for the treatment of memory impairment diseases.