Selenium-containing indolyl compounds: Kinetics of reaction with inflammation-associated oxidants and protective effect against oxidation of extracellular matrix proteins

Trace elements and metal nanoparticles: mechanistic approaches to mitigating chemotherapy-induced toxicity-a review of literature evidence

Anticancer chemotherapy (ACT) remains a cornerstone in cancer treatment, despite significant advances in pharmacology over recent decades. However, its associated side effect toxicity continues to pose a major concern for both oncology clinicians and patients, significantly impacting treatment protocols and patient quality of life. Current clinical strategies to mitigate ACT-induced toxicity have proven largely unsatisfactory, leaving a critical unmet need to block toxicity mechanisms without diminishing ACT's therapeutic efficacy. This review aims to document the molecular mechanisms underlying ACT toxicity and highlight research efforts exploring the protective effects of trace elements (TEs) and their nanoparticles (NPs) against these mechanisms. Our literature review reveals that the primary driver of ACT toxicity is redox imbalance, which triggers oxidative inflammation, apoptosis, endoplasmic reticulum stress, mitochondrial dysfunction, autophagy, and dysregulation of signaling pathways such as PI3K/mTOR/Akt. Studies suggest that TEs, including zinc, selenium, boron, manganese, and molybdenum, and their NPs, can potentially counteract ACT-induced toxicity by inhibiting oxidative stress-mediated pathways, including NF-κB/TLR4/MAPK/NLRP3, STAT-3/NLRP3, Bcl-2/Bid/p53/caspases, and LC3/Beclin-1/CHOP/ATG6, while also upregulating protective signaling pathways like Sirt1/PPAR-γ/PGC-1α/FOXO-3 and Nrf2/HO-1/ARE. However, evidence regarding the roles of lncRNA and the Wnt/β-catenin pathway in ACT toxicity remains inconsistent, and the impact of TEs and NPs on ACT efficacy is not fully understood. Further research is needed to confirm the protective effects of TEs and their NPs against ACT toxicity in cancer patients. In summary, TEs and their NPs present a promising avenue as adjuvant agents for preventing non-target organ toxicity induced by ACT.

Organoselenium Compounds in Medicinal Chemistry

The chemical and biological interest in this element and the molecules bearing selenium has been exponentially growing over the years. Selenium, formerly designated as a toxin, becomes a vital trace element for life that appears as selenocysteine and its dimeric form, selenocystine, in the active sites of selenoproteins, which catalyze a wide variety of reactions, including the detoxification of reactive oxygen species and modulation of redox activities. From the point of view of drug developments, organoselenium drugs are isosteres of sulfur-containing and oxygen-containing drugs with the advantage that the presence of the selenium atom confers antioxidant properties and high lipophilicity, which would increase cell membrane permeation leading to better oral bioavailability. This statement is the paramount relevance considering the big number of clinically employed compounds bearing sulfur or oxygen atoms in their structures including nucleosides and carbohydrates. Thus, in this article we have focused on the relevant features of the application of selenium in medicinal chemistry. With the increasing interest in selenium chemistry, we have attempted to highlight the most significant published data on this subject, mainly concentrating the analysis on the last years. In consequence, the recent advances of relevant pharmacological organoselenium compounds are discussed.

Iodine/Oxone® oxidative system for the synthesis of selenylindoles bearing a benzenesulfonamide moiety as carbonic anhydrase I, II, IX, and XII inhibitors

A wide range of 3-selenylindoles were synthesized via an eco-friendly approach that uses Oxone® as the oxidant in the presence of a catalytic amount of iodine. This mild and economical protocol showed broad functional group tolerance and operational simplicity. A series of novel selenylindoles bearing a benzenesulfonamide moiety were also synthesized and evaluated as carbonic anhydrase inhibitors of the human (h) isoforms hCa I, II, IX, and XII, which are involved in pathologies such as glaucoma and cancer. Several derivatives showed excellent inhibitory activity towards these isoforms in the nanomolar range, lower than that shown by acetazolamide.

Bismuth(III)-Catalyzed Regioselective Selenation of Indoles with Diaryl Diselenides: Synthesis of 3-Selanylindoles

Heterocyclic aryl selenides have recently attracted considerable research interest owing to their applications in biological and pharmaceutical fields. Herein, we describe a simple and general synthesis of 3-selanylindoles via a novel regioselective C-H selenation of indoles using a bismuth reagent as a catalyst. The reactions of indoles with diselenides in the presence of 10 mol% BiI3 at 100 °C in DMF afforded the corresponding 3-selanylindoles in moderate-to-excellent yields. The reaction proceeded efficiently under aerobic conditions by adding only a catalytic amount of BiI3, which was non-hygroscopic and less toxic, and both selanyl groups of the diselenide were transferred to the desired products.

Transition metal-free C(sp3)-H selenation of β-ketosulfones

The installation of selenium groups has become an essential step across a number of industries such as agrochemicals, drug discovery, and materials. However, direct C(sp3)-H selenation, which is most atom economical, remains a formidable challenge, and only a few examples have been reported to date. In this article, we introduce the transition metal-free C(sp3)-H selenation with the easily available β-ketosulfones and diselenides as the material source. This benign protocol permits access to a broad spectrum of α-aryl(alkyl) seleno-β-ketosulfones in high yields with outstanding functional group compatibility. Distinct advantages of this protocol over all previous methods encompass the utilization of base and air as an oxidant, room temperature, and enhanced green chemistry matrices.

A novel diselenide attenuates the carrageenan-induced inflammation by reducing neutrophil infiltration and the resulting tissue damage in mice

Selenium-containing compounds have emerged as promising treatment for redox-based and inflammatory diseases. This study aimed to investigate the in vitro and in vivo anti-inflammatory activity of a novel diselenide named as dibenzyl[diselanediyIbis(propane-3-1diyl)] dicarbamate (DD). DD reacted with HOCl (k = 9.2 x 107 M-1s-1), like glutathione (k = 1.2 x 108 M-1s-1), yielding seleninic and selenonic acid derivatives, and it also decreased HOCl formation by activated human neutrophils (IC50=4.6 μM) and purified myeloperoxidase (MPO) (IC50=3.8 μM). However, tyrosine, MPO-I and MPO-II substrates, did not restore HOCl formation in presence of DD. DD inhibited the oxidative burst in dHL-60 cells with no toxicity up to 25 µM for 48h. Next, an intraperitoneal administration of 25, 50, and 75 mg/kg DD decreased total leukocyte, neutrophil chemotaxis, and inflammation markers (MPO activity, lipid peroxidation, albumin exudation, nitrite, TNF-α, IL-1β, CXCL1/KC, and CXCL2/MIP-2) on a murine model of carrageenan-induced peritonitis. Likewise, 50 mg/kg DD (i.p.) decreased carrageenan-induced paw edema over 5h. Histological and immunohistochemistry analyses of the paw tissue showed decreased neutrophil count, edema area, and MPO, carbonylated, and nitrated protein staining. Furthermore, DD treatment decreased the fMLP-induced chemotaxis of human neutrophils (IC50=3.7 μM) in vitro with no toxicity. Lastly, DD presented no toxicity in a single-dose model using mice (50 mg/kg, i.p.) over 15 days and in Artemia salina bioassay (50 to 2000 µM), corroborating findings from in silico toxicological study. Altogether, these results demonstrate that DD attenuates carrageenan-induced inflammation mainly by reducing neutrophil migration and the resulting damage from MPO-mediated oxidative burst.

Reactions of hypobromous acid with dimethyl selenide, dimethyl diselenide and other organic selenium compounds: kinetics and product formation

Selenium (Se) is an essential micronutrient for many living organisms particularly due to its unique redox properties. We recently found that the sulfur (S) analog for dimethyl selenide (DMSe), i.e. dimethyl sulfide (DMS), reacts fast with the marine oxidant hypobromous acid (HOBr) which likely serves as a sink of marine DMS. Here we investigated the reactivity of HOBr with dimethyl selenide and dimethyl diselenide (DMDSe), which are the main volatile Se compounds biogenically produced in marine waters. In addition, the reactivity of HOBr with further organic Se compounds was tested, i.e., SeMet (as N-acetylated-SeMet), and selenocystine (SeCys2 as N-acetylated-SeCys2), as well as the phenyl-analogs of DMSe and DMDSe, respectively, diphenyl selenide (DPSe) and diphenyl diselenide (DPDSe). Apparent second-order rate constants at pH 8 for the reactions of HOBr with the studied Se compounds were (7.1 ± 0.7) × 107 M-1 s-1 for DMSe, (4.3 ± 0.4) × 107 M-1 s-1 for DMDSe, (2.8 ± 0.3) × 108 M-1 s-1 for SeMet, (3.8 ± 0.2) × 107 M-1 s-1 for SeCys2, (3.5 ± 0.1) × 107 M-1 s-1 for DPSe, and (8.0 ± 0.4) × 106 M-1 s-1 for DPDSe, indicating a very high reactivity of all selected Se compounds with HOBr. The reactivity between HOBr and DMSe is lower than for DMS and therefore this reaction is likely not relevant for marine DMSe abatement. However, the high reactivity of SeMet with HOBr suggests that SeMet may act as a relevant quencher of HOBr.

Development of trisubstituted thiophene-3-arboxamide selenide derivatives as novel EGFR kinase inhibitors with cytotoxic activity

Overexpression of EGFR is one of the eminent oncogenic drivers detected in the development of several human cancers. The increasing incidences of mutation-based resistance in the tyrosine kinase domain call upon the need for the development of a newer class of small-molecule TK inhibitors. Accordingly, a new series of symmetrical trisubstituted thiophene-3-carboxamide selenide derivatives was developed via the hybridization of complementary pharmacophores. Most of the compounds showed a modest to excellent antiproliferative action at 20 μM concentration. The utmost antiproliferative activity was portrayed by compound 16e on the selected cancer cell lines with IC50 < 9 μM, the lowest being 3.20 ± 0.12 μM in the HCT116 cell line. Further, it also displayed an impressive EGFR kinase inhibition with an IC50 value of 94.44 ± 2.22 nM concentration. As a corollary of the reported EGFR inhibition, the nature, energy, and stability of the binding interactions were contemplated via in silico studies.

Electrochemical selenocyclization of 2-ethynylanilines with diselenides: facile and efficient access to 3-selenylindoles

An efficient electrochemical selenocyclization strategy for the synthesis of 3-selenylindoles from 2-ethynylanilines and diselenides has been developed in simple tube- or beaker-type undivided cells under ambient conditions. Notably, these sustainable transformations are completed within a short time with low equivalents of charges, diselenides and electrolytes, exhibiting a broad substrate scope with excellent functional group compatibility. Moreover, a gram-scale electrosynthesis and late-stage functionalization of complex molecules further demonstrate the practical synthetic potential of this facile electrochemical system.

Prolonged maternal exposure to glucocorticoids alters selenoprotein expression in the developing brain

Aberrant activation of the stress-response system in early life can alter neurodevelopment and cause long-term neurological changes. Activation of the hypothalamic-pituitary-adrenal axis releases glucocorticoids into the bloodstream, to help the organism adapt to the stressful stimulus. Elevated glucocorticoid levels can promote the accumulation of reactive oxygen species, and the brain is highly susceptible to oxidative stress. The essential trace element selenium is obtained through diet, is used to synthesize antioxidant selenoproteins, and can mitigate glucocorticoid-mediated oxidative damage. Glucocorticoids can impair antioxidant enzymes in the brain, and could potentially influence selenoprotein expression. We hypothesized that exposure to high levels of glucocorticoids would disrupt selenoprotein expression in the developing brain. C57 wild-type dams of recently birthed litters were fed either a moderate (0.25 ppm) or high (1 ppm) selenium diet and administered corticosterone (75 μg/ml) via drinking water during postnatal days 1 to 15, after which the brains of the offspring were collected for western blot analysis. Glutathione peroxidase 1 and 4 levels were increased by maternal corticosterone exposure within the prefrontal cortex, hippocampus, and hypothalamus of offspring. Additionally, levels of the glucocorticoid receptor were decreased in the hippocampus and selenoprotein W was elevated in the hypothalamus by corticosterone. Maternal consumption of a high selenium diet independently decreased glucocorticoid receptor levels in the hippocampus of offspring of both sexes, as well as in the prefrontal cortex of female offspring. This study demonstrates that early life exposure to excess glucocorticoid levels can alter selenoprotein levels in the developing brain.

Selenium Deficiency Caused Fibrosis as an Oxidative Stress-induced Inflammatory Injury in the Lungs of Mice

Selenium (Se) is a vital trace element in the regulation of inflammation and antioxidant reactions in both animals and humans. Se deficiency is rapidly affecting lung function. The present study investigated the molecular mechanism of Se deficiency aggravates reactive oxygen species (ROS)-induced inflammation, leading to fibrosis in lung. Mice fed with different concentrations of Se to establish the model. In the Se-deficient group, the ROS and malondialdehyde (MDA) was increased, and the activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), and catalase (CAT) reduced. The histopathological observation showed that Se deficiency lead to lung texture damage with varying degrees of degeneration, necrosis, shedding of some alveolar epithelial cells, and inflammatory cell infiltration. Immunohistochemistry showed that the expression of α-smooth muscle actin (α-SMA) increased. The fibrosis index was verified with Sirius red staining. The ELISA and qPCR results showed that the inflammatory cytokines (TNF-α and IL-1β) and ECM (collagen I, collagen IV, fibronectin, and laminin) were increased with ROS increasing, which was induced by Se deficiency. The results displayed that oxidative stress with Se deficiency led to an increase in tissue inhibitors of metalloproteinase (TIMPs), but a decrease in matrix metalloproteinases (MMPs). All the results indicated that Se deficiency induced excessive ROS accumulation to generate inflammation, which disrupted ECM homeostasis and aggravated fibrosis in the lung.

Recent Trends in Hydroxyapatite Supplementation for Osteoregenerative Purposes

Bone regeneration has gained attention in the biomedical field, which has led to the development of materials and synthesis methods meant to improve osseointegration and cellular bone activity. The properties of hydroxyapatite, a type of calcium phosphate, have been researched to determine its advantages for bone tissue engineering, particularly its biocompatibility and ability to interact with bone cells. Recently, the advantages of utilizing nanomolecules of hydroxyapatite, combined with various substances, in order to enhance and combine their characteristics, have been reported in the literature. This review will outline the cellular and molecular roles of hydroxypatite, its interactions with bone cells, and its nano-combinations with various ions and natural products and their effects on bone growth, development, and bone repair.

Silver-catalyzed direct selanylation of indoles: synthesis and mechanistic insights

Herein we describe the Ag(i)-catalyzed direct selanylation of indoles with diorganoyl diselenides. The reaction gave 3-selanylindoles with high regioselectivity and also allowed direct access to 2-selanylindoles when the C3 position of the indole ring was blocked via a process similar to Plancher rearrangement. Experimental analyses and density functional theory calculations were carried out in order to picture the reaction mechanism. Among the pathways considered (via concerted metalation-deprotonation, Ag(iii), radical, and electrophilic aromatic substitution), our findings support a classic electrophilic aromatic substitution via Lewis adducts between Ag(i) and diorganoyl diselenides. The results also afforded new insights into the interactions between Ag(i) and diorganoyl diselenides.

Aerial Oxygen-Driven Selenocyclization of O-Vinylanilides Mediated by Coupled Fe3+/Fe2+ and I2/I- Redox Cycles

In the past decade, selenocyclization has been extensively exploited for the preparation of a wide range of selenylated heterocycles with versatile activities. Previously, selenium electrophile-based and FeCl3-promoted methods were employed for the synthesis of selenylated benzoxazines. However, these methods are limited by starting material availability and low atomic economy, respectively. Inspired by the recent catalytic selenocyclization approaches based on distinctive pathways, we rationally constructed an efficient and greener double-redox catalytic system for the access to diverse selenylated benzoxazines. The coupling of I2/I- and Fe3+/Fe2+ catalytic redox cycles enables aerial O2 to act as the driving force to promote the selenocyclization. Control and test redox experiments confirmed the roles of each component in the catalytic system, and a PhSeI-based pathway is proposed for the selenocyclization process.

Iodine pentoxide-mediated oxidative selenation and seleno/thiocyanation of electron-rich arenes

A simple and efficient method for the regioselective selenation of electron-rich arenes by employing non-metal inorganic iodine pentoxide (I₂O₅) as a reaction promoter under ambient conditions has been developed. The present protocol showed broad functional group tolerance and easy-to-operate and time-economical features. Additionally, this protocol also allows access to 3-seleno and 3-thiocyanoindoles by the use of readily available selenocyanate and thiocyanate salts. A mechanistic study indicated that the transformation operated through selenenyl iodide-induced electrophilic substitution processes.

Iodine-Mediated Multicomponent Cascade Cyclization and Sulfenylation/Selenation: Synthesis of Imidazo[2,1-a]isoquinoline Derivatives

A novel multicomponent cascade cyclization and sulfenylation/selenation using aryl methyl ketones, isoquinolin-1-amine, and sodium arylsulfinates/1,2-diphenyldiselane to synthesize imidazo[2,1-a]isoquinoline derivatives in one-pot via the construction of two C-N bonds and one C-S/C-Se bond has been reported. This multicomponent reaction realizes simultaneous C(sp³)-H amination and sulfenylation/selenation, avoiding complicated prior substrate preparation. This process has simple operating conditions and good substrate compatibility.

The Problem of Malnutrition Associated with Major Depressive Disorder from a Sex-Gender Perspective

Major depressive disorder (MDD) is an incapacitating condition characterized by loss of interest, anhedonia and low mood, which affects almost 4% of people worldwide. With rising prevalence, it is considered a public health issue that affects economic productivity and heavily increases health costs alone or as a comorbidity for other pandemic non-communicable diseases (such as obesity, cardiovascular disease, diabetes, inflammatory bowel diseases, etc.). What is even more noteworthy is the double number of women suffering from MDD compared to men. In fact, this sex-related ratio has been contemplated since men and women have different sexual hormone oscillations, where women meet significant changes depending on the age range and moment of life (menstruation, premenstruation, pregnancy, postpartum, menopause…), which seem to be associated with susceptibility to depressive symptoms. For instance, a decreased estrogen level promotes decreased activation of serotonin transporters. Nevertheless, sexual hormones are not the only triggers that alter neurotransmission of monoamines and other neuropeptides. Actually, different dietary habits and/or nutritional requirements for specific moments of life severely affect MDD pathophysiology in women. In this context, the present review aims to descriptively collect information regarding the role of malnutrition in MDD onset and course, focusing on female patient and especially macro- and micronutrient deficiencies (amino acids, ω3 polyunsaturated fatty acids (ω3 PUFAs), folate, vitamin B12, vitamin D, minerals…), besides providing evidence for future nutritional intervention programs with a sex-gender perspective that hopefully improves mental health and quality of life in women.

Iso-seco-tanapartholide activates Nrf2 signaling pathway through Keap1 modification and oligomerization to exert anti-inflammatory effects

Covalent modification of Keap1 results in reducing ubiquitination and the accumulation of Nrf2, which subsequently initiates the transcription of cellular anti-oxidant and anti-inflammatory genes. Iso-seco-tanapartholide (IST), a sesquiterpene isolated from the traditional Chinese medicine Artemisia argyi, had been reported to possess NF-κB inhibitory activity. However, its deep anti-inflammatory effects and direct target have never been reported. Here we show that IST activated Nrf2 and increased its target gene expression. In particular, LPS-caused inflammation in vitro and in vivo was mitigated by IST-induced Nrf2 activation but aggravated by Nrf2 inhibition. Mechanically, IST targeted Keap1 proteins via alkylating its cysteine residues 151, 273, 288, and so on. Subsequently, the modifying agent IST was displaced by intermolecular sulfhydryl disulfide interchange to lead to a disulfide dimer of Keap1. The resulting conformational change of Keap1 liberated Nrf2 from sequestration and allowed it translocation to the nucleus to activate the transcriptional program. Further studies demonstrated that Keap1 dimer formation contributed to the anti-inflammatory effects of IST. Taken together, our findings reveal a new mechanism for Nrf2 activation and provide a potential lead compound to treat inflammatory diseases through targeting Keap1.

Preparation of selenyl 1,3-oxazines via PhICl2/Cu2O-promoted aminoselenation of O-homoallyl benzimidates with diselenides

A practical electrophilic aminoselenation of O-homoallyl benzimidate with diselenides promoted by PhICl₂/Cu₂O has been developed. The easily available and stable diselenides were used as selenium sources. Various selenyl 1,3-oxazines, which are important frameworks in medicinal and biological chemistry, were easily obtained in moderate to good yields for the first time. Easy scaleup and scalability make this method attractive for the preparation of other valuable organoselenides.

Amidation-Ketonization-Selenation of Terminal Alkynes Using TEMPO and Elemental Selenium

Herein, we present a novel silver- or copper-mediated direct amidation-ketonization-selenation of terminal alkynes for the synthesis of α-oxo-selenoamides. The reaction utilized easily accessible elemental selenium as the source of selenium. In addition, the ¹⁸O labeling experiment revealed that TEMPO is the oxygen source of the carbonyl group. The reaction takes advantage of an unsaturated C≡C bond to construct new C═O, C═Se, and C-N bonds in one step.

Protective effects of selenium in tacrolimus-induced lung toxicity: potential role of heme oxygenase 1

The present study aimed to evaluate the protective effects of selenium (Sel) administration against tacrolimus (Tac) - induced lung toxicity and to assess the relation between heme oxygenase 1 (HO-1) and these effects. The study was conducted on 36 Wistar male albino rats equally divided into four groups: (i) normal control; (ii) Sel (0.1 mg/kg per day p.o. for four weeks); (iii) TAC 3 mg/mL as single oral dose on 27th day; and (iv) Tac + Sel. Lung tissues, lung homogenate, and bronchoalveolar lavage of the sacrificed animals were investigated biochemically and histopathologically, by immunohistochemistry or by PCR. The Tac group showed significantly lower expression of HO-1. Administration of Sel was associated with increased HO-1 expression. Oxidative (malondialdehyde, reduced glutathione, superoxide dismutase, myeloperoxidase, and glutathione peroxidase activity) and nitrosative stress (nitric oxide) markers and markers of inflammation (interleukin 1β (IL-1β), IL-6, and IL-10) showed changes corresponding to HO-1 levels in rat groups. Tac group showed the highest expression of caspase-3. Sel exerted a protective role against Tac-induced lung toxicity.

Stress and the Brain: An Emerging Role for Selenium

The stress response is an important tool in an organism’s ability to properly respond to adverse environmental conditions in order to survive. Intense acute or chronic elevation of glucocorticoids, a class of stress hormone, can have deleterious neurological effects, however, including memory impairments and emotional disturbances. In recent years, the protective role of the antioxidant micronutrient selenium against the negative impact of externally applied stress has begun to come to light. In this review, we will discuss the effects of stress on the brain, with a focus on glucocorticoid action in the hippocampus and cerebral cortex, and emerging evidence of an ability of selenium to normalize neurological function in the context of various stress and glucocorticoid exposure paradigms in rodent models.

Neuroprotective Effect of 3-[(4-Chlorophenyl)selanyl]-1-methyl-1H-indole on Hydrogen Peroxide-Induced Oxidative Stress in SH-SY5Y Cells

Extensive data have reported the involvement of oxidative stress in the pathogenesis of neuropsychiatric disorders, prompting the pursuit of antioxidant molecules that could become adjuvant pharmacological agents for the management of oxidative stress-associated disorders. The 3-[(4-chlorophenyl)selanyl]-1-methyl-1H-indole (CMI) has been reported as an antioxidant and immunomodulatory compound that improves depression-like behavior and cognitive impairment in mice. However, the exact effect of CMI on specific brain cells is yet to be studied. In this context, the present study aimed to evaluate the antioxidant activity of CMI in H₂O₂-induced oxidative stress on human dopaminergic neuroblastoma cells (SH-SY5Y) and to shed some light into its possible mechanism of action. Our results demonstrated that the treatment of SH-SY5Y cells with 4 µM CMI protected them against H₂O₂ (343 μM)-induced oxidative stress. Specifically, CMI prevented the increased number of reactive oxygen species (ROS)-positive cells induced by H₂O₂ exposure. Furthermore, CMI treatment increased the levels of reduced glutathione in SH-SY5Y cells. Molecular docking studies demonstrated that CMI might interact with enzymes involved in glutathione metabolism (i.e., glutathione peroxidase and glutathione reductase) and H₂O₂ scavenging (i.e., catalase). In silico pharmacokinetics analysis predicted that CMI might be well absorbed, metabolized, and excreted, and able to cross the blood-brain barrier. Also, CMI was not considered toxic overall. Taken together, our results suggest that CMI protects dopaminergic neurons from H₂O₂-induced stress by lowering ROS levels and boosting the glutathione system. These results will facilitate the clinical application of CMI to treat nervous system diseases associated with oxidative stress.

Selenium-doped hydroxyapatite nanoparticles for potential application in bone tumor therapy

In the present study we have studied the incorporation and release of selenite ions (SeO₃^2-) in hydroxyapatite nanoparticles for the treatment of bone tumors. Two types of selenium-doped hydroxyapatite (HASe) nanoparticles (NPs) with a nominal Se/(P + Se) molar ratio ranging from 0.01 up to 0.40 have been synthesized by a new and mild wet method. The two series of samples were thoroughly characterized and resulted to be slightly different in chemical composition, but they had similar properties in terms of morphology and degree of crystallinity. Selenium release from HASe was investigated under neutral and acidic conditions to simulate both healthy tissues and the low-pH environment surrounding a tumor mass, respectively. The comparison of the release profiles at two pH values clearly showed the possibility of modulating the Se release by simply changing the amount of Se in the HASe particles. The correlation between the physicochemical properties of HASe and their dissolution as a function of pH has been also investigated to facilitate future application of the NPs as chemotherapeutic adjuvant agents. Finally, the cytotoxic activity of HASe was evaluated using prostate (PC3) and breast (MDA-MB-231) cancer cells as well as healthy human bone marrow stem cells (hBMSc). HASe NPs exerted a good cytocompatibility at low concentration of Se but, with high Se doping concentration, they displayed strong cytotoxicity.

3-[(4-chlorophenyl)selanyl]-1-methyl-1H-indole ameliorates long-lasting depression- and anxiogenic-like behaviors and cognitive impairment in post-septic mice: Involvement of neuroimmune and oxidative hallmarks

Only in the last decade the long-term consequences of sepsis started to be studied and even less attention has been given to the treatment of psychological symptoms of sepsis survivors. It is estimated that 60% of sepsis survivors have psychological disturbances, including depression, anxiety, and cognitive impairment. Although the causative factors remain largely poorly understood, blood-brain barrier (BBB) disturbances, neuroinflammation, and oxidative stress have been investigated. Therefore, we sought to explore if the immunomodulatory and antioxidant selenocompound 3-[(4-chlorophenyl)selanyl]-1-methyl-1H-indole (CMI) would be able to ameliorate long-term behavioral and biochemical alterations in sepsis survivors male Swiss mice. CMI treatment (1 mg/kg, given orally for seven consecutive days) attenuated depression- and anxiogenic-like behaviors and cognitive impairment present one month after the induction of sepsis (lipopolysaccharide, 5 mg/kg intraperitoneally). Meantime, CMI treatment modulated the number of neutrophils and levels of reactive species in neutrophils, lymphocytes, and monocytes. In addition, peripheral markers of liver and kidneys dysfunction (AST, ALT, urea, and creatinine) were reduced after CMI treatment in post-septic mice. Notably, CMI treatment to non-septic mice did not alter AST, ALT, urea, and creatinine levels, indicating the absence of acute hepatotoxicity and nephrotoxicity following CMI treatment. Noteworthy, CMI ameliorated BBB dysfunction induced by sepsis, modulating the expression of inflammation-associated genes (NFκB, IL-1β, TNF-α, IDO, COX-2, iNOS, and BDNF) and markers of oxidative stress (reactive species, nitric oxide, and lipid peroxidation levels) in the prefrontal cortices and hippocampi of mice. In conclusion, we unraveled crucial molecular pathways that are impaired in post-septic mice and we present CMI as a promising therapeutic candidate aimed to manage the long-lasting behavioral alterations of sepsis survivors to improve their quality of life.

Interaction kinetics of selenium-containing compounds with oxidants

Selenium compounds have been identified as potential oxidant scavengers for biological applications due to the nucleophilicity of Se, and the ease of oxidation of the selenium centre. Previous studies have reported apparent second order rate constants for a number of oxidants (e.g. HOCl, ONOOH) with some selenium species, but these data are limited. Here we provide apparent second order rate constants for reaction of selenols (RSeH), selenides (RSeR') and diselenides (RSeSeR') with biologically-relevant oxidants (HOCl, H₂O₂, other peroxides) as well as overall consumption data for the excited state species singlet oxygen (¹O₂). Selenols show very high reactivity with HOCl and ¹O₂, with rate constants > 10⁸ M^-1 s^-1, whilst selenides and diselenides typically react with rate constants one- (selenides) or two- (diselenides) orders of magnitude slower. Rate constants for reaction of diselenides with H₂O₂ and other hydroperoxides are much slower, with k for H₂O₂ being <1 M^-1 s^-1, and for amino acid and peptide hydroperoxides ~10² M^-1 s^-1. The rate constants determined for HOCl and ¹O₂ with these selenium species are greater than, or similar to, rate constants for amino acid side chains on proteins, including the corresponding sulfur-centered species (Cys and Met), suggesting that selenium containing compounds may be effective oxidant scavengers. Some of these reactions may be catalytic in nature due to ready recycling of the oxidized selenium species. These data may aid the development of highly efficacious, and catalytic, oxidant scavengers.

The selenocompound 1-methyl-3-(phenylselanyl)-1H-indole attenuates depression-like behavior, oxidative stress, and neuroinflammation in streptozotocin-treated mice

Major depressive disorder (MDD) is a chronic mental illness affecting a wide range of people worldwide. The pathophysiology of MDD is not completely elucidated, but it is believed that oxidative stress and neuroinflammation are involved. In light with this, the aim of the present study was to investigate whether a single administration of the antioxidant 1-methyl-3-(phenylselanyl)-1H-indole (MFSeI) was able to reverse the streptozotocin-induced depression-like behavior, oxidative stress, and neuroinflammation in mice. MFSeI (10 mg/kg) was administered intragastrically (i.g.) 24 h after the intracerebroventricular injection of STZ (0.2 mg/4 μL/per mouse). Thirty minutes after MFSeI administration, behavioral tests and neurochemical analyses were performed. Fluoxetine (10 mg/kg, i.g.) was used as a positive control. MFSeI and fluoxetine were able to reverse the STZ-induced depression-like behavior, as evidenced by decreased immobility time in the forced swimming test and increased grooming time in the splash test. Mechanistically, MFSeI reversed the increased levels of reactive species and lipid peroxidation in the prefrontal cortices and hippocampi of STZ-treated mice. Additionally, neuroinflammation (i.e. expression of NF-κB, IL-1β, and TNF-α) and the reduced mRNA levels of BDNF in the and hippocampi of depressed mice were reversed by treatment with MFSeI. Fluoxetine did not improve the STZ-induced alterations at the levels of reactive species, NF-κB and BDNF in the prefrontal cortices neither the levels of TNF-α in both brain regions. Together, these data suggest that the MFSeI may be a promising compound with antidepressant-like action, reducing oxidative stress and modulating inflammatory pathways in the brain of depressed mice.

The antioxidant and immunomodulatory compound 3-[(4-chlorophenyl)selanyl]-1-methyl-1H-indole attenuates depression-like behavior and cognitive impairment developed in a mouse model of breast tumor

Psychiatric alterations are often found in patients with breast cancer even before the initiation of adjuvant therapy, resulting in a poor quality of life. It has become accepted that neuroinflammation and oxidative stress are involved in the pathophysiology of depression and cognitive impairment. Herein, we tested the hypothesis that treatment with the antioxidant and immunomodulatory selenium-containing compound 3-[(4-chlorophenyl)selanyl]-1-methyl-1H-indole (CMI)could attenuate behavioral and neurochemical alterations in a mammary (4T1) tumor model. Female BALB/c mice were subcutaneously inoculated with 4T1 cancer cells (1 × 10⁵ cells/mice) or PBS. From days 14 to 20, mice received daily gavage with canola oil or CMI. On day 21, mice were submitted to behavioral tests followed by euthanasia. We found that CMI did not alter tumor growth, body weight, and body temperature in tumor-bearing mice. Importantly, treatment with CMI abrogated tumor-induced depression-like behavior and cognitive impairment. By the time CMI improved the behavioral alterations, it had reduced tumor-induced neuroinflammation (altered expression of NFκB, IL-1β, TNF-α, IL-10, IDO, and COX-2) and oxidative stress (altered expression of iNOS and Nrf2, and levels of reactive species, nitric oxide, lipid peroxidation, and superoxide dismutase activity) in the prefrontal cortices and hippocampi of mice. A molecular docking approach suggested the ability of CMI to inhibit the activity of iNOS and COX-2. Together, our results indicate that CMI treatment may attenuate depression and cognitive impairment in 4T1 tumor-bearing mice, and be a groundbreaking strategy for the treatment of cancer-related psychiatric symptoms to improve the quality of life of cancer patients.

Depression-like behavior, hyperglycemia, oxidative stress, and neuroinflammation presented in diabetic mice are reversed by the administration of 1-methyl-3-(phenylselanyl)-1H-indole

Oxidative stress and neuroinflammation are found both in diabetes mellitus and major depressive disorder (MDD). In addition to damage in peripheral organs, such as liver and kidney, diabetic patients have a higher risk of developing depression. In this sense, the objective of the present study was to characterize the antidepressant-like effect of a selenium-containing compound, the 1-methyl-3-(phenylselanyl)-1H-indole (MFSeI), in streptozotocin (STZ)-induced diabetic mice. STZ (200 mg/kg, i.p.) was used to induce diabetes mellitus type I, and after seven days, the administration of MFSeI (10 mg/kg, i.g.) was initiated and followed for the next 14 days. Twenty-four hours after the last administration of MFSeI, the behavioral tests were performed, followed by euthanasia. The treatment with MFSeI was able to reverse the hyperglycemia induced by STZ. MFSeI also decreased the plasma levels of biomarkers of liver and kidney damage. Importantly, MFSeI reversed the depression-like behavior induced by STZ in the tail suspension test and forced swimming test without promoting locomotor alterations. Furthermore, MFSeI reversed the increased levels of reactive species and lipid peroxidation in the prefrontal cortex (PFC), hippocampus (HC), liver, and kidney of STZ-treated mice. Treatment with MFSeI also decreased the expression of tumor necrosis factor-alpha, inducible nitric oxide synthase and indoleamine 2,3-dioxygenase, while increasing the expression of interleukin-10, insulin receptor substrate-1 and glucose transport-4 in the PFC and HC of mice. Taken together, the results indicate the effectiveness of MFSeI against depression-like behavior and central and peripheral complications caused by diabetes in mice.

4-Octyl itaconate inhibits aerobic glycolysis by targeting GAPDH to exert anti-inflammatory effects

Activated macrophages switch from oxidative phosphorylation to aerobic glycolysis, similar to the Warburg effect, presenting a potential therapeutic target in inflammatory disease. The endogenous metabolite itaconate has been reported to regulate macrophage function, but its precise mechanism is not clear. Here, we show that 4-octyl itaconate (4-OI, a cell-permeable itaconate derivative) directly alkylates cysteine residue 22 on the glycolytic enzyme GAPDH and decreases its enzyme activity. Glycolytic flux analysis by U¹³C glucose tracing provides evidence that 4-OI blocks glycolytic flux at GAPDH. 4-OI thereby downregulates aerobic glycolysis in activated macrophages, which is required for its anti-inflammatory effects. The anti-inflammatory effects of 4-OI are replicated by heptelidic acid, 2-DG and reversed by increasing wild-type (but not C22A mutant) GAPDH expression. 4-OI protects against lipopolysaccharide-induced lethality in vivo and inhibits cytokine release. These findings show that 4-OI has anti-inflammatory effects by targeting GAPDH to decrease aerobic glycolysis in macrophages.

Toxicological evaluation of 3-(4-Chlorophenylselanyl)-1-methyl-1H-indole through the bovine oocyte in vitro maturation model

The development of new bioactive molecules based on the molecular hybridization has been widely explored. In line with this, reliable tests should be employed to give information about the toxicology of these new molecules. In this sense, the use of in vitro tests is a valuable tool, especially the in vitro maturation of oocytes (IVM), which is an efficient resource to discover the potential toxicity of synthetic molecules. Thus, the aim of the present study was to evaluate the toxicological effects of the selenium-containing indolyl compound 3-(4-Chlorophenylselanyl)-1-methyl-1H-indole (CMI), on different quality parameters of bovine oocytes through the IVM. Different concentrations of the CMI compound (0, 25, 50, 100, 200 μM) were supplemented during the in vitro maturation process. After, the oocyte maturation rate, glutathione (GSH) levels, reactive oxygen species (ROS) levels, membrane, and mitochondrial integrity were evaluated. The results showed that the lowest concentration of CMI induced the highest GSH production (P < 0.05), an important marker of cytoplasmic quality and maturation. All treatments increased ROS production in relation to non-supplementation (P < 0.05). In addition, oocyte maturation was reduced only with the highest concentration of CMI (P < 0.05). Supplementation with CMI did not impact mitochondrial activity, integrity and cell membrane. To our knowledge, this is the first study that evaluates CMI on the oocyte in vitro maturation process. Importantly, our results did not find any toxic effect of CMI on bovine oocytes. CMI was efficient for cytoplasmic maturation by promoting an increase in the intracellular levels of glutathione.

The selenium-containing compound 3-((4-chlorophenyl)selanyl)-1-methyl-1H-indole reverses depressive-like behavior induced by acute restraint stress in mice: modulation of oxido-nitrosative stress and inflammatory pathway

RATIONALE AND OBJECTIVES

Stress-induced alterations in oxidative and inflammatory parameters have been implicated in the pathophysiology of mood disorders. Based on the antioxidant and anti-inflammatory properties of the selenium-containing compound 3-((4-chlorophenyl)selanyl)-1-methyl-1H-indole (CMI), we assessed its ability to reverse depression-like behavioral alterations, neuroinflammation, and oxidative imbalance induced by acute restraint stress.

METHODS

Mice submitted to restraint for 240 min received CMI (1 or 10 mg/kg, orally) 10 min after the end of the stress induction. Behavioral and biochemical tests were carried out after further 30 min.

RESULTS

Restraint-induced depression-like behavior in the tail suspension test (TST), splash test, and new object exploration test was reversed by CMI. None of the treatments evoked locomotor alteration. In addition, CMI abrogated restraint-induced increases in plasma levels of corticosterone and in markers of oxidative stress and impaired superoxide dismutase and catalase activity in the prefrontal cortex (PFC) and hippocampus (HC). CMI also blocked stress-induced downregulation of mRNA levels of glucocorticoid receptor and brain-derived neurotrophic factor and upregulation of nuclear factor kappa B, inducible nitric oxide synthase, tumor necrosis alpha, indoelamine-2,3-dioxygenase, and glycogen synthase kinase 3 beta in PFC and HC.

CONCLUSIONS

These preclinical results indicate that administration of selenium-containing compounds might help to treat depression associated with inflammation and oxidative stress. Graphical abstract ᅟ.

3-(4-Chlorophenylselanyl)-1-methyl-1H-indole promotes recovery of neuropathic pain and depressive-like behavior induced by partial constriction of the sciatic nerve in mice

3-(4-Chlorophenylselanyl)-1-methyl-1H-indole (CMI) is an organoselenium compound that presents antioxidant activity, antinociceptive, anti-inflammatory and antidepressive-like effect in mice in previous studies conducted by our research group. In this study, we evaluate the anti-allodynic, anti-hyperalgesic and antidepressant-like effects of CMI on partial sciatic nerve ligation (PSNL) in male adult Swiss mice (25-35 g) as well as the involvement of oxidative stress in these effects. Mice underwent PSNL surgery and after 4 weeks they were treated with CMI (10 mg/kg, intragastric route [i.g.]) or vehicle. The treatment with CMI (10 mg/kg, i.g.) reversed the increased the percentage of response to Von-Frey Hair (VFH) stimulation, decreased the latency time to nociceptive response in the hot-plate test, increased immobility time in the forced swimming test (FST) and decreased groomings activity in the splash test, all induced by PSNL. Additionally, CMI also reversed increased the levels of reactive oxygen species (ROS) and lipid peroxidation in cortex and hippocampus and plasmatic levels of corticosterone in mice, induced by PSNL. Results demonstrate that CMI reversed behavioral and biochemical alterations in the dyad pain-depression induced by PSNL and possibly modulation of oxidative system.

Repeated administration of a selenium-containing indolyl compound attenuates behavioural alterations by streptozotocin through modulation of oxidative stress in mice

Although the pathophysiology of major depression disorder (MDD) is still poorly understood, mounting evidence suggests that the brains of depressed patients are under oxidative stress, leading to depressive symptoms that may include anxiety and cognitive impairment. This study aimed to investigate if the seleno-organic compound 1-methyl-3-(phenylselanyl)-1H-indole (MFSeI) reverses the depression- and anxiogenic-like behaviour, cognitive impairment and oxidative stress induced by the intra-cerebroventricular injection of streptozotocin (STZ; 0.2 mg/4 μl/per mouse) in Swiss male mice. Twenty-four hours after the STZ injection, mice were treated with MFSeI (10 mg/kg, intra-gastrically), or vehicle solution, once daily for seven days. The behavioural tests were performed 30 min after the final MFSeI administration, followed by euthanasia and collection of the cerebral cortex and hippocampus. Administration of MFSeI reversed the depression- and anxiogenic-like behaviour and cognitive impairment induced by STZ, in mice. Neurochemical analyses demonstrated that MFSeI reversed the STZ-increased levels of reactive species, nitrite, lipid peroxidation and acetylcholinesterase activity in the cerebral cortex and hippocampus of mice. Moreover, a single administration of MFSeI (300 mg/kg, intra-gastrically) did not cause acute toxicity in Swiss male mice. Altogether, our data suggest that MFSeI exhibits antidepressant- and anxiolytic-like effects and improves the cognition of STZ-treated mice, without any toxicity.

Oxidative dual C–H selenation of imidazoheterocycles with ethers or alkanes using selenium powder via a radical pathway

A DCP-mediated oxidative dual C–H selenation radical reaction of imidazoheterocycles with ethers or alkanes using selenium powder was developed.

Selenium Species: Current Status and Potentials in Cancer Prevention and Therapy

Selenium (Se) acts as an essential trace element in the human body due to its unique biological functions, particularly in the oxidation-reduction system. Although several clinical trials indicated no significant benefit of Se in preventing cancer, researchers reported that some Se species exhibit superior anticancer properties. Therefore, a reassessment of the status of Se and Se compounds is necessary in order to provide clearer insights into the potentiality of Se in cancer prevention and therapy. In this review, we organize relevant forms of Se species based on the three main categories of Se-inorganic, organic, and Se-containing nanoparticles (SeNPs)-and overview their potential functions and applications in oncology. Here, we specifically focus on the SeNPs as they have tremendous potential in oncology and other fields. In general, to make better use of Se compounds in cancer prevention and therapy, extensive further study is still required to understand the underlying mechanisms of the Se compounds.

Myeloperoxidase oxidation of methionine associates with early cystic fibrosis lung disease

Cystic fibrosis (CF) lung disease progressively worsens from infancy to adulthood. Disease-driven changes in early CF airway fluid metabolites may identify therapeutic targets to curb progression.CF patients aged 12-38 months (n=24; three out of 24 later denoted as CF screen positive, inconclusive diagnosis) received chest computed tomography scans, scored by the Perth-Rotterdam Annotated Grid Morphometric Analysis for CF (PRAGMA-CF) method to quantify total lung disease (PRAGMA-%Dis) and components such as bronchiectasis (PRAGMA-%Bx). Small molecules in bronchoalveolar lavage fluid (BALF) were measured with high-resolution accurate-mass metabolomics. Myeloperoxidase (MPO) was quantified by ELISA and activity assays.Increased PRAGMA-%Dis was driven by bronchiectasis and correlated with airway neutrophils. PRAGMA-%Dis correlated with 104 metabolomic features (p<0.05, q<0.25). The most significant annotated feature was methionine sulfoxide (MetO), a product of methionine oxidation by MPO-derived oxidants. We confirmed the identity of MetO in BALF and used reference calibration to confirm correlation with PRAGMA-%Dis (Spearman's ρ=0.582, p=0.0029), extending to bronchiectasis (PRAGMA-%Bx; ρ=0.698, p=1.5×10^-4), airway neutrophils (ρ=0.569, p=0.0046) and BALF MPO (ρ=0.803, p=3.9×10^-6).BALF MetO associates with structural lung damage, airway neutrophils and MPO in early CF. Further studies are needed to establish whether methionine oxidation directly contributes to early CF lung disease and explore potential therapeutic targets indicated by these findings.

Convenient synthesis of selenyl-indoles via iodide ion-catalyzed electrochemical C–H selenation

Reported herein is a transition metal- and oxidant-free method for the synthesis of selenyl heteroarenes with diselenides through iodide ion-catalyzed electrolytic selenation.

Rose Bengal catalysed photo-induced selenylation of indoles, imidazoles and arenes: a metal free approach

A photo-induced, metal-free strategy was used for the direct C(sp²)–H bond selenylation of indoles, imidazoles and arenes using Rose Bengal as a photocatalyst.