Structural modifications into diphenyl diselenide molecule do not cause toxicity in mice

Nano-based formulations as an approach for providing a novel identity for organoselenium compounds

The organoselenium compounds belong to a class of synthetic molecules that displays a remarkable spectrum of promising pharmacological properties. Despite the huge amount of preclinical data that supports a bright outlook for organoselenium compounds, some toxicity issues and physicochemical limitations delay the development of more advanced studies. Currently, several scientific reports demonstrated that the association of nanotechnology has emerged as an alternative to improve solubility and safety issues of these molecules as well as enhance pharmacological properties. Therefore, our main objective was to address studies that reported the development and biological evaluations of nano-based formulations to synthetic organoselenium compounds incorporation by constructing an integrative literature review. The data survey was performed using the Science Direct, PubMed, Web of Science, and SCOPUS online databases, covering studies that were published from January 2011 up to October 2021. In the last decade, there has been an exponential growth in research regarding the incorporation of synthetic organoselenium compounds into distinct nanocarrier systems such as nanocapsules, nanoemulsions, micelles, and others, reinforcing that the association of such molecules and nanotechnology is a promising alliance. The reports investigated many nanosystems containing selenium organic molecules intending oral, intravenous, and cutaneous applications. Besides that, these systems were evaluated in a variety of in vitro techniques and in vivo models, concerning their pharmacological potential, biodistribution profile, and safety. In summary, the findings indicate that the production of nano-based formulations containing organoselenium compounds either improved physicochemical and biological properties or minimize toxicological issues of compounds.

Therapeutic Benefits of Selenium in Hematological Malignancies

Supplementing chemotherapy and radiotherapy with selenium has been shown to have benefits against various cancers. This approach has also been shown to alleviate the side effects associated with standard cancer therapies and improve the quality of life in patients. In addition, selenium levels in patients have been correlated with various cancers and have served as a diagnostic marker to track the efficiency of treatments or to determine whether these selenium levels cause or are a result of the disease. This concise review presents a survey of the selenium-based literature, with a focus on hematological malignancies, to demonstrate the significant impact of selenium in different cancers. The anti-cancer mechanisms and signaling pathways regulated by selenium, which impart its efficacious properties, are discussed. An outlook into the relationship between selenium and cancer is highlighted to guide future cancer therapy development.

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.

Selenium Compounds as Novel Potential Anticancer Agents

The high number of new cancer incidences and the associated mortality continue to be alarming, leading to the search for new therapies that would be more effective and less burdensome for patients. As there is evidence that Se compounds can have chemopreventive activity, studies have begun to establish whether these compounds can also affect already existing cancers. This review aims to discuss the different classes of Se-containing compounds, both organic and inorganic, natural and synthetic, and the mechanisms and molecular targets of their anticancer activity. The chemical classes discussed in this paper include inorganic (selenite, selenate) and organic compounds, such as diselenides, selenides, selenoesters, methylseleninic acid, 1,2-benzisoselenazole-3[2H]-one and selenophene-based derivatives, as well as selenoamino acids and Selol.

Selective activity of diselenides against Aedes aegypti (Diptera: Culicidae) larvae

INTRODUCTION:

Aedes aegypti (L.) is the major vector of arboviruses that causes serious public health concerns in tropical and subtropical countries.

METHODS:

We examined the larvicidal activity of 1,2-diphenyldiselenide [(PhSe)₂] and 1,2-bis(4-chlorophenyl) diselenide [(p-ClPhSe)₂] and determine its toxicity to different non-target organisms.

RESULTS:

(PhSe)₂ and (p-ClPhSe)₂ killed Ae. aegypti L3 larvae with LC_50/24h values of 65.63 µM (20.48 mg/L) and 355.19 µM (135.33 mg/L), respectively. (PhSe)₂ was not toxic to the four model organisms.

CONCLUSIONS:

(PhSe)₂ is a larvicidal compound with selective action against Ae. aegypti larvae. The mechanisms of action of (PhSe)₂ under field conditions remain to be investigated.

Nanoencapsulation potentiates the cutaneous anti-inflammatory effect of p,p'-methoxyl-diphenyl diselenide: Design, permeation, and in vivo studies of a nanotechnological-based carrageenan gum hydrogel

This study aimed to investigate the feasibility of preparing a hydrogel based on (OMePhSe)₂-loaded poly(Ɛ-caprolactone) nanocapsules using carrageenan gum as a gel-forming agent. Furthermore, the anti-inflammatory action of hydrogel was assessed in an animal model of skin lesion induced by ultraviolet B (UVB) radiation in mice. Nanocapsules were prepared using the interfacial deposition of preformed polymer technique. The hydrogels were obtained by the direct addition of nanocapsules suspension in carrageenan gum (3%). Formulations with free compound, vehicle, and blank nanocapsules were also produced. The hydrogels were characterized by pH, compound content, diameter, spreadability, rheological behavior, and permeation profile. The pharmacological performance was assessed in an animal model of skin injury induced by UVB-radiation in male Swiss mice. All hydrogels had pH around 7.0, compound content close to the theoretical value (2.5 mg/g), an average diameter in nanometric range (around 350 nm), non-Newtonian flow with pseudoplastic behavior, and suitable spreadability factor. The nano-based hydrogel increased the compound content in the epidermis and dermis layers in comparison to the formulation prepared with non-encapsulated (OMePhSe)₂. Stability studies revealed that the hydrogels of nanoencapsulated compound had superior physicochemical stability in comparison to the formulation of free (OMePhSe)_2. Moreover, topical treatment with the hydrogel containing (OMePhSe)₂ loaded-nanocapsules was more effective in reducing ear thickness and the inflammatory process induced by UVB radiation in mice. Herein, a polysaccharide was applied as a gel-forming agent using a simple and low-cost method. Besides, a superior permeation profile and improved pharmacological action were achieved by the compound encapsulation.

m-Trifluoromethyl-diphenyl Diselenide Regulates Prefrontal Cortical MOR and KOR Protein Levels and Abolishes the Phenotype Induced by Repeated Forced Swim Stress in Mice

The present study aimed to investigate the m-trifluoromethyl-diphenyl diselenide [(m-CF₃-PhSe)₂] effects on prefrontal cortical MOR and KOR protein levels and phenotype induced by repeated forced swim stress (FSS) in mice. Adult Swiss mice were subjected to repeated FSS sessions, and after that, they performed the spontaneous locomotor/exploratory activity, tail suspension, and splash tests. (m-CF₃-PhSe)₂ (0.1 to 5 mg/kg) was administered to mice 30 min before the first FSS session and 30 min before the subsequent repeated FSS. (m-CF₃-PhSe)₂ abolished the phenotype induced by repeated FSS in mice. In addition, a single FSS session increased μ but reduced δ-opioid receptor contents, without changing the κ content. Mice subjected to repeated FSS had an increase in the μ content when compared to those of naïve group or subjected to single FSS. Repeated FSS induced an increase of δ-opioid receptor content compared to those mice subjected to single FSS. However, the δ-opioid receptor contents were lower than those found in the naïve group. The mice subjected to repeated FSS showed an increase in the κ-opioid receptor content when compared to that of the naïve mice. (m-CF₃-PhSe)₂ regulated the protein contents of μ and κ receptors in mice subjected to repeated FSS. These findings demonstrate that (m-CF₃-PhSe)₂ was effective to abolish the phenotype induced by FSS, which was accompanied by changes in the contents of cortical μ- and κ-opioid receptors.

Ultrasound-promoted copper-catalyzed synthesis of bis-arylselanyl chrysin derivatives with boosted antioxidant and anticancer activities

Herein we report the use of ultrasonic irradiation (US) in the synthesis of six new semi-synthetic selenium-containing chrysin derivatives by a simple and effective methodology utilizing CuI as catalyst, in good to excellent yields (60-89%). It was observed that US accelerates the reaction compared to conventional heating with excellent selectivity for diselenylated products. Compounds were tested for their antioxidant and anticancer activities in vitro and it was observed that the presence of selenium in the A-ring of chrysin enhanced both antioxidant and anticancer properties. Semi-synthetic 6,8-bis(o-tolylselanyl)-chrysin 3b has the best radical scavenging activity of DPPH (I_max: 39.79µM) and ABTS⁺ (IC₅₀: 6.5µM) radicals. Similarly, in the Reactive Species (RS) assay, 3b showed high antioxidant activity in mice cortex (IC₅₀: 5.67µM), whereas 6,8-bis(p-anisoylselanyl)-chrysin 3c was the more active in the hippocampus (IC₅₀: 5.63µM). The Se-chrysins were effective in prevention of lipid peroxidation, highlighting 6,8-bis(p-fluorophenylselanyl)-chrysin 3d in cortex (IC₅₀: 0.54µM) and 3b in hippocampus (IC₅₀: 0.27µM). In addition, 3d was effective in inhibiting human lung adenocarcinoma (A549) cells growth, with a IC₅₀ of 19.9µM after 72h of treatment, while 6,8-bis(p-anisoylselanyl)-chrysin 3c presented the higher antiproliferative activity after 48h of treatment (IC₅₀ of 41.4µM).

Opioid system contribution to the antidepressant-like action of m-trifluoromethyl-diphenyl diselenide in mice: A compound devoid of tolerance and withdrawal syndrome

Animal and clinical researches indicate that the opioid system exerts a crucial role in the etiology of mood disorders and is a target for intervention in depression treatment. This study investigated the contribution of the opioid system to the antidepressant-like action of acute or repeated m-trifluoromethyl-diphenyl diselenide administration to Swiss mice. m-Trifluoromethyl-diphenyl diselenide (50 mg/kg, intragastric) produced an antidepressant-like action in the forced swimming test from 30 min to 24 h after treatment. This effect was blocked by the µ and δ-opioid receptor antagonists, naloxonazine (10 mg/kg, intraperitoneally) and naltrindole (3 mg/kg, intraperitoneally), and it was potentiated by a κ-opioid receptor antagonist, norbinaltrophimine (1 mg/kg, subcutaneously ). Combined treatment with subeffective doses of m-trifluoromethyl-diphenyl diselenide (10 mg/kg, intragastric) and morphine (1 mg/kg, subcutaneously) resulted in a synergistic antidepressant-like effect. The opioid system contribution to the m-trifluoromethyl-diphenyl diselenide antidepressant-like action was also demonstrated in the modified tail suspension test, decreasing mouse immobility and swinging time and increasing curling time, results similar to those observed using morphine, a positive control. Treatment with m-trifluoromethyl-diphenyl diselenide induced neither tolerance to the antidepressant-like action nor physical signs of withdrawal, which could be associated with the fact that m-trifluoromethyl-diphenyl diselenide did not change the mouse cortical and hippocampal glutamate uptake and release. m-Trifluoromethyl-diphenyl diselenide treatments altered neither locomotor nor toxicological parameters in mice. These findings demonstrate that m-trifluoromethyl-diphenyl diselenide elicited an antidepressant-like action by direct or indirect μ and δ-opioid receptor activation and the κ-opioid receptor blockade, without inducing tolerance, physical signs of withdrawal and toxicity.

p,p'-Methoxyl-diphenyl diselenide-loaded polymeric nanocapsules are chemically stable and do not induce toxicity in mice

Organoselenium compounds have been targeted to new therapeutic tools development due to their pharmacological actions. However, some toxicity issues and physicochemical limitations delay the clinical application of these compounds. The incorporation of organoselenium molecules into nanostructured systems arises as a promising alternative to overcome such restrictions. The current study proposed the characterization of the polymeric nanocapsules of p,p'-methoxyl-diphenyl diselenide [(OMePhSe)₂] as well as the evaluation of the in vivo toxicity and biodistribution profile. The nanocapsules, which were composed by medium-chain triglycerides as the oil core and poly(ε-caprolactone) as the polymeric wall, showed nanometric size (236±4), low polydispersity (<0.2), negative zeta potential (-5.4±0.06), neutral pH values (7.2±0.08) and a high encapsulation efficiency (98%). Besides, the nanoencapsulation process increased the (OMePhSe)₂ stability. The repeated intragastric administration of (OMePhSe)₂ nanoencapsulated (25mg/kg/day during 7days) did not cause any alteration in the oxidative status, hematological parameters, and plasma biochemical markers of cellular damage. Moreover, the (OMePhSe)₂ incorporation into nanocapsules increased the selenium concentrations in the tissues (kidneys, liver and plasma) suggesting an improvement in its oral bioavailability.

p,p'-Methoxyl-diphenyl diselenide elicits an antidepressant-like effect in mice without discontinuation anxiety phenotype

Major depressive disorder is the most severe and debilitating disease among psychiatric illnesses. The abrupt interruption of antidepressant treatment may lead to a complex physiological and neuropsychiatric syndrome. The organoselenium compound (MeOPhSe)₂ has been reported to have neuroprotective properties in animal models. The study aimed to investigate the effects of single or repeated administration of (MeOPhSe)₂ on depressive-like behavior and if the compound administration, and its discontinuation, may affect the anxiolytic-like phenotype in Swiss mice. The results showed that repeated intragastric administration of (MeOPhSe)₂ (dose range: 0.1-5mg/kg), different from a single administration, reduced the immobility time in the mouse tail suspension test. A single administration of (MeOPhSe)₂ at a dose of 5mg/kg decreased the immobility time, increased the swimming time and did not alter the climbing behavior in the modified forced swimming test (mFST). Repeated administration of (MeOPhSe)₂ decreased the immobility time, did not alter the swimming time and increased the climbing behavior in the mouse mFST. Repeated administration of (MeOPhSe)₂ at a dose of 5mg/kg elicited a mouse anxiolytic-like phenotype in the elevated plus maze and light-dark tests. Markers of hepatic and renal function tests were not altered by repeated administration of (MeOPhSe)₂ to mice. The findings indicate that a single or repeated administration of (MeOPhSe)₂ elicited an antidepressant-like action in mice. Moreover, repeated treatment with (MeOPhSe)₂ produced an anxiolytic-like action in mice and its profile remained stable after discontinuation.

m-Trifluoromethyl-diphenyldiselenide as a pharmacological tool to treat preference symptoms related to AMPH-induced dependence in rats

Amphetamine (AMPH) abuse is a world concern and a serious public health problem. Repeated administration of high doses of AMPH induces neuropsychiatric consequences, including addiction, reward and psychosis, whose pharmacological treatment has shown limited effectiveness. The m-trifluoromethyl-diphenyldiselenide [(m-CF3-PhSe)2] has been documented as a promising pharmacological agent in different animal models related to oxidative damage. In this study, we examined the influence of (m-CF3-PhSe)2 on withdrawal following re-exposure to AMPH. Wistar rats received d,l-AMPH or saline in the conditioned place preference (CPP) paradigm for 8days. Then, half of each initial (AMPH or saline) experimental group was treated with (m-CF3-PhSe)2 or vehicle, resulting in four final groups: i) Saline/vehicle; ii) (m-CF3-PhSe)2/saline; iii) AMPH/vehicle; and iv) AMPH/(m-CF3-PhSe)2. After fourteen days of (m-CF3-PhSe)2 treatment, animals were re-exposed to AMPH or vehicle in the CPP paradigm for three more days in order to assess drug re-conditioning and memory/locomotor activity, performed 24h after AMPH re-exposure in the CPP and the Y maze, respectively. Subsequently, ex-vivo assays were carried out in samples of the prefrontal cortex (PFC) of the animals. The (m-CF3-PhSe)2 treatment was able to prevent AMPH-induced re-conditioning symptoms in rats. Behavioral observations in the Y maze task showed no significant changes. AMPH exposure was able to increase 5-HT uptake as well as oxidative damage in the PFC, whereas (m-CF3-PhSe)2 treatment exerted a preventative effect against these alterations. The current findings suggest that (m-CF3-PhSe)2 might be considered a promising therapeutic tool for AMPH-induced addiction.

Effects of diphenyl and p-chloro-diphenyl diselenides on feeding behavior of rats

RATIONALE

The searching for safe and effective antiobesity drugs has been the subject of intense research. Previous studies have shown several pharmacological applications of organoselenium compounds; however, their possible anorectic-like actions have not been investigated.

OBJECTIVE

This study aims to investigate the effects of (PhSe)2 and (p-ClPhSe)2 on feeding behavior of rats and their potential as weight-reducing agents.

METHODS

The effects of intraperitoneal administration of diselenides were investigated through the microstructural pattern of feeding behavior, behavioral satiety sequence (BSS), hypothalamic serotonin (5-HT) uptake, body weight, and epididymal fat content of male rats.

RESULTS

Our findings demonstrated that food intake of fasted rats was reduced by both diselenides (1 and 10 mg/kg). Diphenyl diselenide [(PhSe)2] (1 mg/kg) and p-chloro-diphenyl diselenide [(p-ClPhSe)2] (10 mg/kg) decreased the frequency, mean duration, and mean size of meals compared with the control treatment. The BSS structure was preserved when organoselenium compounds (1 mg/kg) were administered, and it was associated to a displacement to the left when the resting period started indicating a satiating action. Inhibition of 5-HT uptake in the hypothalamus (∼20 %) was also found in rats treated with low doses of (PhSe)2 and (p-ClPhSe)2 (1 mg/kg). Treatments with a high dose of both diselenides (10 mg/kg) carried out for 7 days induced weight loss and epididymal fat reduction in sated rats.

CONCLUSION

This study suggests that diselenides caused a satiating action in rats that could be partially explained by the inhibition of hypothalamic 5-HT uptake. These organoselenium compounds were potential weight-reducing agents when repeatedly administered.

“The green side of the moon: ecofriendly aspects of organoselenium chemistry”

Key aspects for the development of a greener synthesis and the use of the organoselenium compounds.

Effects of 4,4'-dichloro-diphenyl diselenide (ClPhSe)2 on toxicity induced by mercuric chloride in mice: a comparative study with diphenyl diselenide (PhSe)2

The effects of 4,4'-dichloro-diphenyl diselenide (ClPhSe)(2) on the toxicity induced by mercuric chloride (HgCl(2)) were investigated and compared with diphenyl diselenide (PhSe)(2). Mice received HgCl(2) for three days and, on the third day, received (PhSe)(2) or (ClPhSe)(2). The results verified that the administration of (ClPhSe)(2) in mice exposed to HgCl(2) increased renal δ-aminolevulinate dehydratase (δ-ALA-D), Na(+), K(+)-ATPase activities and non-protein thiol (NPSH) levels and also decreased thiobarbituric acid-reactive substances (TBARS) and ascorbic acid levels, when compared to mice exposed to HgCl(2)+(PhSe)(2). Plasma and urinary protein, hemoglobin and hematocrit levels and histological parameters were also ameliorated in mice exposed to HgCl(2)+(ClPhSe)(2). In addition, the hepatic damage in mice exposed to HgCl(2)+(PhSe)(2) was reduced in animals exposed to (ClPhSe)(2). To sum up, the introduction of a functional group (chloro) in the aromatic ring of diaryl diselenide reduced the toxicity of this compound in liver and kidney of mice exposed to HgCl(2).

Substituted diaryl diselenides: cytotoxic and apoptotic effect in human colon adenocarcinoma cells

AIMS

To investigate the effects and study the underlying cell death mechanisms of diaryl diselenides, including: diphenyl diselenide (C(6)H(5)Se)(2); 4-chlorodiphenyl diselenide (4-ClC(6)H(4)Se)(2); 3-(trifluoromethyl)-diphenyl diselenide (3-CF(3)C(6)H(4)Se)(2) and 4-methoxydiphenyl diselenide (4-MeOC(6)H(4)Se)(2), on the human colon adenocarcinoma cell line HT-29.

MAIN METHODS

The viability of HT-29 cells after exposure to the diaryl diselenides and its substituted structures was based on the MTT assay. To verify if cell death was mediated throughout apoptosis mechanisms, flow cytometry and real-time PCR (qPCR) analyses were conducted.

KEY FINDINGS

The MTT assay and flow cytometry analyses showed that (3-CF(3)C(6)H(4)Se)(2) and (4-MeOC(6)H(4)Se)(2) induced cytotoxicity through apoptosis mechanisms in HT-29 cells. qPCR revealed there was an up-regulation of pro-apoptotic (Bax, casapase-9, caspase-8, apoptosis-inducing factor (AIF) and Endonuclease G (EndoG)) and cell-cycle arrest genes (p53 and p21) and down-regulation of anti-apoptotic (Bcl-2 and survivin) and Myc genes.

SIGNIFICANCE

These results demonstrate that (3-CF(3)C(6)H(4)Se)₂ and (4-MeOC(6)H(4)Se)(2) have the potential to induce apoptosis in HT-29 cells through the activation of caspase-dependent and independent pathways and through cell-cycle arrest.

High doses of 2,2'-dithienyl diselenide cause systemic toxicity in rats: an in vitro and in vivo study

Organoselenium compounds have important pharmacological properties. However, these compounds can cause toxicity, typically related to oxidation of endogenous thiols. The aim of this study was to investigate whether 2,2'-dithienyl diselenide (DTDS) has potential toxicity in vitro and in vivo. Therefore, sulfhydryl-containing enzyme activities, δ-aminolevulinic acid dehydratase (δ-ALA-D) and Na(+) -K(+) -ATPase were used to predict DTDS toxicity in rat brain homogenate in vitro. In in vivo experiments, a DTDS administration (50 or 100 mg kg(-1) , p.o.) to rats was performed and toxicological parameters were determined. DTDS inhibited δ-ALA-D (IC50 2 µm) and Na(+) -K(+) -ATPase (IC50 17 µm) activities in vitro. The inhibitory effect of DTDS on δ-ALA-D and Na(+) -K(+) -ATPase activities was restored by dithiothreitol. DTDS (5-25 µm) elicited a thiol oxidase-like activity. In vivo, DTDS (50 and 100 mg kg(-1) ) caused systemic toxicity, evidenced by a decrease in water and food intakes and body weight gain, as well as the death of rats. DTDS at the dose of 100 mg kg(-1) increased plasma alanine and aspartate aminotransferase activities and decreased urea levels. At 50 and 100 mg kg(-1) , it increased lipid peroxidation levels. At the highest dose, DTDS inhibited δ-ALA-D activity. By contrast, Na(+) -K(+) -ATPase activity and antioxidant defense were not altered in the brains of rats exposed to DTDS. In conclusion, interaction with the cisteinyl residues seems to mediate the inhibitory effect of DTDS on sulfhydryl-containing enzymes in vitro. In addition, high oral doses of DTDS induce toxicity in rats.