Dietary supplementation of male mice with inorganic, organic or nanoparticle selenium preparations: evidence supporting a putative gut-thyroid-male fertility axis

Selenium (Se) is linked to physiological homeostasis. Male mice (n = 8/group) were fed control (AIN93G) or diets enriched in sodium selenite (NaSe, 5.6 ppm), methylselenocysteine (Met, 4.7 ppm), diphenyl diselenide (DPDS, 14.2 ppm), or nanoselenium (NanoSe, 2.7 ppm); dietary Se ascertained by inductively-coupled plasma mass spectrometry. At 4 weeks testes, sperm, thyroids, blood and stool were collected to assess histoarchitecture, circulating hormones (thyroxine, T4; triiodothyronine, T3; thyroid stimulating hormone, TSH) and gut microbiome (16S rRNAV3-V4 amplicon sequencing). Supplemented NaSe, Met, and NanoSe increased plasma testosterone and testis glutathione peroxidases (GPx-1/4) while testicular superoxide dismutase and catalase increased slightly in the NanoSe group indicating a selective antioxidant response. Overall, NanoSe and NaSe enhanced male reproductive factors. All thyroids isolated from Se-supplemented mice contained marginal vacuoles and a lower follicle area vs control. Nano-Se enhanced thyroidiodothyronine deiodinase-1 (DIO1) expression however, thyroid GPx-1/4 remained unchanged. Supplemented NaSe and DPDSl increased plasma T3/T4 ratio, while plasma TSH was unchanged. Microbiome analyses showed that NanoSe was most efficacious in altering composition (judged by α-diversity, Shannon index and taxon richness) while the NaSe diet showed the greatest overall change in α-diversity. Dietary Se supplementation, particularly encapsulated NanoSe, may improve male fertility factors by enhancing the gut-thyroid-fertility axis.

Mitigation of ischemia/reperfusion injury via selenium nanoparticles: Suppression of STAT1 to inhibit cardiomyocyte oxidative stress and inflammation

Ischemia/reperfusion injury (I/RI) following myocardial infarction, a leading cause of global morbidity and mortality, is characterized by detrimental oxidative stress and inflammation. In response, we proposed an I/RI alleviation strategy using the intravenous injection of spherical selenium nanoparticles (SeNPs) synthesized by a template method. Single-cell sequencing revealed these proposed SeNPs exhibited exceptional antioxidant and anti-inflammatory properties, disrupting the STAT1-ROS cycle, therefore preserving mitochondrial respiration and inhibiting caspase-mediated cardiomyocyte apoptosis. Additionally, SeNPs reduced macrophage infiltration and diminished the subsequent release of inflammatory mediators during I/RI. In vivo, SeNPs significantly improved myocardial function while decreasing myocardial apoptosis and fibrosis. These results collectively demonstrated that template method synthesized spherical SeNPs may serve as a promising candidate for enhancing myocardial infarction treatments, while the suppression of STAT1 could be a pivotal mechanism for alleviating ischemia/reperfusion injury following myocardial infarction.

Biochemical strategy-based hybrid hydrogel dressing-mediated in situ synthesis of selenoproteins for DFU immunity-microbiota homeostasis regulation

Chronic consequences of diabetes that are most commonly encountered are diabetic foot ulcers (DFUs), driven by microbiota-immune system dyshomeostasis, eventually leading to delayed wound healing. Available therapies, such as systemic or topical administration of anti-inflammatory or antimicrobial agents, are limited due to antibiotic resistance and immune dysfunction. Herein, a hybrid hydrogel dressing is developed as the artificial bioadhesive barrier at wound sites to maintain microbial and immunological homeostasis locally and have potent anti-inflammatory effects. Specifically, Zero-valent selenium nanoparticles are synthesized and encapsulated into the alginate-polyacrylamide interpenetrating hydrogel networks, during which trehalose is adopted to modify the network defects. Besides, as an anti-adhesion agent, trehalose has shown the ability to prevent immune degradation by reducing bacteria binding to HUVECs. The obtained hybrid hydrogel dressing serves as a physical barrier against microbiome invasion, further regulates the composition of the wound microbiome to restore microbial immune homeostasis at the wound site, and cooperatively relieves DFU-associated symptoms. Meanwhile, the hydrogel dressing can synthesize selenoproteins in situ based on biochemical strategies and significantly reduce the secretion of proinflammatory cytokines. The proposed biochemical strategy based on the hybrid hydrogel dressings can efficiently restore microbiota-immune homeostasis in the wounds, presenting a promising approach for DFU therapy in clinics.

Selenium as a brightening agent for peroxidase-like activity regulation of MXene@CeO2 sensing platform

Selenium is a nutritionally essential trace element for human health, but efficient or excessive intake both causes physiological diseases. Here, we propose that selenium as a brightening agent significantly increase the peroxidase (POD)-like activity of MXene@CeO2, which CeO2 nanoparticles in-situ grow on MXene as the sensing platform. Based on the selenium-stimulated POD-like activity of MXene@CeO2, a simple, low-cost, and reliable colorimetric method is constructed for quantitative analysis of selenium. The great advantage of MXene@CeO2 platform selecting selenium as brightening agent exhibits good selectivity for other 23 interfering ions, allowing the discrimination of selenium in practical samples rapidly and precisely even at 3.5 nM. Moreover, MXene@CeO2 platform selectively catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) instead of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium (ABTS) under the same condition. This study not only offers a utility sensing platform for quick detection of selenium but also opens an avenue for the rational design of element sensors for point-of-care application.

Selenium Distribution and Speciation in Tissues from Rats Administered with Non-Native Selenotrisulfides

Selenotrisulfides (STS, R-S-Se-S-R) are metabolic intermediates in the bioconversion of inorganic Se species to organoselenium compounds. These Se species are reactive with a variety of endogenous molecules, particularly thiol-containing proteins, with this reactivity facilitating Se transport and subsequent utilization within the body. In this study, X-ray fluorescence microscopy (XFM) and high energy resolution fluorescence detected X-ray absorption spectroscopy (HERFD-XAS) were applied to investigate Se distribution and speciation in vivo. Male rats administered with 1 mg Se/kg b.w. as selenious acid (SA), L-penicillamine selenotrisulfide (PenSSeSPen) or selenenyl penicillamine bound to rat serum albumin (RSA-SSeSPen) showed statistically significant elevations in Se concentrations in the kidney, liver, and blood after 48 h treatment; however, no change in Se concentration was observed in the testes. Notably, XFM revealed a strong colocalization of Se and Cu in the renal cortex, a phenomenon previously observed in cultured cells and in rats fed diets supplemented with 5 mg Se/kg as selenite. Linear combination and principal component analyses of Se Kα1 HERFD-XAS spectra revealed marked differences in Se speciation between the renal cortex and medulla and between red blood cells and plasma for all groups, including the control. STS were identified in linear combination fits of spectra from all tissues, except the testes. These results highlight the vital roles of STS in the intracellular reduction and transport of Se throughout the bloodstream and various tissues.

Advantages of Novel Anti-cancer Selenosemicarbazones: Preferential Reactivity of Their Fe(III), Cu(II), and Zn(II) Complexes with Key Physiological Reductants/Ligands Versus Isosteric Thiosemicarbazones

Fe(III) complexes of clinically trialed thiosemicarbazones demonstrate deleterious oxy-myoglobin and oxy-hemoglobin oxidation. Therefore, the PPP4pSe selenosemicarbazone analogues were designed with several PPP4pSe Fe(III) complexes completely preventing deleterious oxy-myoglobin oxidation. This was ascribed to the decreased potentials of their Fe(III) complexes and steric hindrance effects. The Fe(III), Cu(II), and Zn(II) complexes of PPP4pSe demonstrated greater reactivity with physiological reductants/ligands (glutathione, l-cysteine, or l-ascorbate), than respective complexes of the isosteric thiosemicarbazone, PPP4pT. Considering this: (1) [Fe(PPP4pSe)2]+ demonstrated increased reduction relative to [Fe(PPP4pT)2]+ with glutathione and l-cysteine, while l-ascorbate led to comparable reduction; (2) glutathione led to complete dissociation of [Zn(PPP4pSe)2], while incomplete dissociation of [Zn(PPP4pT)2] occurred; and (3) [Cu(PPP4pSe)Cl] demonstrated complete coordinate sphere substitution with glutathione, l-cysteine, and l-ascorbate, whereas [Cu(PPP4pT)Cl] demonstrated partial substitution. The role of glutathione in all three latter reactions is significant, given the greater reactivity of the selenosemicarbazone, and glutathione's key role in selenosemicarbazone and thiosemicarbazone anticancer activity.

Making Cells as a "Nirvana Phoenix": Precise Coupling of Precursors Prior to ROS Bursts for Intracellular Synthesis of Quantum Dots

Rationally coupling natural biochemical reactions for live-cell synthesis of inorganic nanocrystals with fluorescence, such as quantum dots (QDs) especially near-infrared (NIR), holds significant potential for in situ labeling and bioimaging. However, the introduced exogenous reactants and intracellularly produced species, e.g., reactive oxygen species (ROS), often cause cell damage, decreasing the fluorescence of the QDs. Herein, we have found that cell-adaptable selenocystine ((Cys-Se)2) can be reduced to biocompatible low-valence Se precursors, which could be subsequently hijacked by timely added Ag-glutathione (AgSG) to be transformed into NIR Ag2Se QDs. Such a comprehensive control strategy can inhibit the production of cytotoxic Se species and ROS bursts, significantly increasing the cell viability from 4 to 80% and enhancing the fluorescence of intracellularly synthesized Ag2Se QDs by over 8.7 times. Notably, the proliferative and in vivo tumorigenic capacities of the cells with strong NIR fluorescence-emitting functions could be maintained, enabling long-term tracking of cell division and disease progression. This work has provided new insights into fully excavating the potential of cells for the synthesis of inorganic nanocrystals by designing biocompatible precursors and also opened a new window for conventional synthetic biology from organic to inorganic.

Selenium promotes neural development through the regulation of GPX4 and SEPP1 in an iPSC-derived neuronal model

Selenium (Se) is incorporated into selenoproteins in the form of selenocysteine, which has biological functions associated with neural development. Unfortunately, the specific roles and mechanisms of selenoproteins at different stages of neuronal development are still unclear. Therefore, in this study, we successfully established a neuronal model derived from induced pluripotent stem cells (iPSC-iNeuron) and used Se nanoparticles (SeNPs@LNT) with high bioavailability to intervene at different stages of neural development in iPSC-iNeuron model. Interestingly, our results showed that SeNPs@LNT could not only accelerate the proliferation of neural progenitor cells (NPCs) by upregulating glutathione peroxidase 4 (GPX4) during the NPC stage, but also can promote neuronal differentiation by increasing selenoprotein P (SEPP1) during the neuronal stage, resulting in efficient and rapid neural development. In addition, further mechanistic studies showed that SeNPs@LNT can regulate selenoproteins by activating the PI3K/Akt/Nrf2 signaling pathway, thereby affecting neuronal development. Notably, Further analysis of ASD patients in National Center for Biotechnology Information single-cell RNA-seq datasets also revealed significantly lower GPX4 expression within NRGN-expressing neurons in ASD patients, and GO enrichment analysis of genes in NRGN-expressing neurons from ASD patients showed that the downregulation of selenoproteins due to aberrant selenoprotein synthesis may be closely associated with decreased ATP synthesis resulting from abnormal mitochondrial and respiratory chain signaling pathways. Taken together, this study provides evidence that SeNPs@LNT exerts a beneficial effect on early neural development through the regulation of selenoproteins.

Reusable Selenenyl Iodide-Initiated Cascade Cyclization of Polyenes with N-terminating Groups

Although cascade cyclization of polyenes has advanced remarkably, most reported examples are limited to carbon- or oxygen-terminating groups, with nitrogen-terminating cyclizations remaining rare. In this work, we developed a cascade cyclization of polyenes with N-terminating groups, initiated by an isolable selenenyl iodide (RSeI) bearing a cavity-shaped substituent. Acid-labile substrates were successfully employed in the cascade cyclization. Compared with commonly used organoselenium reagents, a selenenyl iodide, characterized by its unique soft electrophilic nature, proved to be the most effective in promoting the cascade reaction. Furthermore, the stabilizing effect of the cavity-shaped substituent enabled the isolation of a selenenic acid (RSeOH), which was generated via oxidative β-selenoxide elimination from the cyclized product during its derivatization to an olefin, as a stable compound. We also developed a method for regenerating the starting selenenyl iodide from the selenenic acid. The reusability of the selenenyl iodide renders the series of molecular transformations environmentally benign by reducing unwanted organoselenium waste.

Multicomponent Reaction Integrating Selenium(II)-Nitrogen Exchange (SeNEx) Chemistry and Copper-Catalyzed Azide-Alkyne Cycloaddition (CuAAC)

Multicomponent reactions (MCRs) are powerful tools for rapidly constructing compound libraries with sufficient molecular diversity and complexity. Herein, to fully leverage a third aspect of molecular diversity enabled by the selenium-nitrogen exchange (SeNEx) reaction between alkynes and benzoselenazolones, a novel CuI-catalyzed three-component reaction has been successfully developed. This reaction integrates SeNEx with CuAAC click chemistry, enabling rapid and regioselective synthesis of 1,4,5-trisubstituted 5-seleno-1,2,3-triazoles with high atom economy and good to excellent yields (65 examples, 50%-95%). Notably, this MCR demonstrates excellent functional group tolerance and features modular, predictable, robust, mild reaction conditions, and operational simplicity (air and water compatibility). Extensive mechanism studies have revealed that this reaction proceeds by a unique SeNEx-CuAAC tandem reaction pathway, distinguishing it from conventional copper(I)-catalyzed interrupted click reactions. Importantly, a mononuclear σ-bound copper(I)-acetylide Cu1 was synthesized and confirmed to be an efficient catalyst for the SeNEx reaction. This discovery provides crucial mechanistic insights into the preferential reactivity of alkynyl groups toward SeNEx over CuAAC. Furthermore, preliminary biological activity screening identified compound 14 as a potent inhibitor of Escherichia coli β $\upbeta$ -glucuronidase (EcGUS), with an IC50 value of 3.16 µM. These findings underscore the significant potential of this MCR in synthetic chemistry, medical chemistry, and chemical biology.

Comparative Study on the Effects of Selenium-Enriched Yeasts with Different Selenomethionine Contents on Gut Microbiota and Metabolites

Selenium is an essential trace element for human health, but it mainly exists in an inorganic form that cannot be directly absorbed by the body. Brewer's yeast efficiently converts inorganic selenium into bioavailable organic selenium, making selenium-enriched yeast highly significant for human health research. Selenomethionine (SeM) is an important indicator for evaluating the quality of selenium-enriched yeast. Brewer's yeast was selected as the experimental subject, and the digestion of this yeast (Brewer's yeast) was simulated using an in vitro biomimetic gastrointestinal reactor to evaluate the effects of selenium-enriched yeast with various SeM levels on the gut flora of a healthy population. The experimental design comprised normal yeast (control group, OR), yeast containing moderate SeM levels (selenium-enriched group, SE), yeast containing high SeM levels (high-selenium group, MU), and a commercially available group comprising selenium-enriched yeast tablets (MA). The MU group exhibited a significantly higher concentration of short-chain fatty acids than the OR and MA groups during 48 h of fermentation, with significant differences observed (p < 0.05). Sequencing results revealed that the MU group showed significantly increased relative abundances of Bacteroidetes and Actinobacteria, while exhibiting a decreased ratio of Firmicutes to Bacteroidetes, which may simultaneously affect multiple metabolic pathways in vivo. These findings support the theory that selenium-enriched yeast with a high SeM has a more positive effect on human health compared with traditional yeast and offer new ideas for the development and application of selenium-enriched yeast.

Translational Selenium Nanoparticles Promotes Clinical Non-small-cell Lung Cancer Chemotherapy via Activating Selenoprotein-driven Immune Manipulation

Reconstructing the tumor immune microenvironment is an effective strategy to enhance therapeutic efficacy limited by immunosuppression in non-small-cell lung cancer (NSCLC). In this study, it is found that selenium (Se) depletion and immune dysfunction are present in patients with advanced NSCLC compared with healthy volunteers. Surprisingly, Se deficiency resulted in decreased immunity and accelerated rapid tumor growth in the mice model, which further reveals that the correlation between micronutrient Se and lung cancer progression. This pioneering work achieves 500-L scale production of Se nanoparticles (SeNPs) at GMP level and utilizes it to reveal how and why the trace element Se can enhance clinical immune-mediated treatment efficacy against NSCLC. The results found that translational SeNPs can promote the proliferation of NK cells and enhance its cytotoxicity against cancer cells by activating mTOR signaling pathway driven by GPXs to regulate the secretion of cytokines to achieve an antitumor response. Moreover, a clinical study of an Investigator-initiated Trial shows that translational SeNPs supplementation in combination with bevacizumab/cisplatin/pemetrexed exhibits enhanced therapeutic efficacy with an objective response rate of 83.3% and a disease control rate of 100%, through potentiating selenoprotein-driven antitumor immunity. Taken together, this study, for the first time, highlights the translational SeNPs-enhanced therapeutic efficacy against clinical advanced NSCLC.

Live-cell synthesis of biocompatible quantum dots

Quantum dots (QDs) exhibit fluorescence properties with promising prospects for biomedical applications; however, the QDs synthesized in organic solvents shows poor biocompatibility, limiting their use in biological systems. We developed an approach for synthesizing QDs in live cells by coupling a series of intracellular metabolic pathways in a precise spatial and temporal sequence. We have validated this approach in yeast (Saccharomyces cerevisiae), Staphylococcus aureus, Michigan Cancer Foundation-7 (MCF-7) and Madin-Darby canine kidney (MDCK) cells. The intracellularly synthesized QDs are inherently stable and biocompatible, making them suitable for the direct in situ labeling of cells and cell-derived vesicles. Here, we provide an optimized workflow for the live-cell synthesis of QDs by using S. cerevisiae, S. aureus or MCF-7 cells. In addition, we detail a cell-free aqueous synthetic system (quasi-biosynthesis) containing enzymes, electrolytes, peptides and coenzymes, which closely mimics the intracellular synthetic conditions used in our cell culture system. In this solution, we synthesize biocompatible ultrasmall QDs that are easier to purify and characterize than those synthesized in cells. The live-cell-synthesized QDs can be used for bioimaging and microvesicle detection, whereas the quasi-biosynthesized QDs are suitable for applications such as biodetection, biolabeling and real-time imaging. The procedure can be completed in 3-4 d for live-cell QD synthesis and 2 h for the quasi-biosynthesis of QDs. The procedure is suitable for users with expertise in chemistry, biology, materials science and synthetic biology. This approach encourages interested researchers to engage in the field of QDs and develop further biomedical applications.

Thiopurine S-methyltransferase - An important intersection of drug-drug interactions in thiopurine treatment

Understanding the molecular mechanisms of medicines is crucial for developing novel drugs, for repurposing existing medicines, and for predicting toxicities. Thiopurine S-methyltransferase (TPMT) serves as an exemplary case in personalized medicine, as its activity is influenced by genetic variants, co-factors, substrates, and inhibitors, which lead to diverse outcomes in thiopurine therapy. This comprehensive review explores the role of TPMT in drug-drug interactions by investigating its interactions with co-factors, substrates, and inhibitors. We focus on the principal interactions of TPMT with clinically relevant inhibitors, and add to this information with molecular docking analyses for the substrate and co-factor binding sites of TPMT. Notably, methotrexate and sulfasalazine emerged as the top-ranked compounds with favorable docking scores for the co-factor binding site, while furosemide is presented as the highest ranked inhibitor for the substrate binding site. Furthermore, we highlight the chemical and structural properties governing ligand binding to TPMT. We support the molecular characteristics by using a summary of clinical implications. Examining the molecular interactions between substrates or inhibitors and TPMT not only addresses therapeutic consequences, but also reveals potential novel indications of interacting compounds. These insights are also invaluable for identifying endogenous ligands and enhancing our understanding of TPMT's biological function.

Selenium metabolism and selenoproteins function in brain and encephalopathy

Selenium (Se) is an essential trace element of the utmost importance to human health. Its deficiency induces various disorders. Se species can be absorbed by organisms and metabolized to hydrogen selenide for the biosynthesis of selenoproteins, selenonucleic acids, or selenosugars. Se in mammals mainly acts as selenoproteins to exert their biological functions. The brain ranks highest in the specific hierarchy of organs to maintain the level of Se and the expression of selenoproteins under the circumstances of Se deficiency. Dyshomeostasis of Se and dysregulation of selenoproteins result in encephalopathy such as Alzheimer's disease, Parkinson's disease, depression, amyotrophic lateral sclerosis, and multiple sclerosis. This review provides a summary and discussion of Se metabolism, selenoprotein function, and their roles in modulating brain diseases based on the most currently published literature. It focuses on how Se is utilized and transported to the brain, how selenoproteins are biosynthesized and function physiologically in the brain, and how selenoproteins are involved in neurodegenerative diseases. At the end of this review, the perspectives and problems are outlined regarding Se and selenoproteins in the regulation of encephalopathy.

Calling for a comprehensive risk assessment of selenium in drinking water

In the last two decades, research has elucidated that selenium, a trace element, has both nutritional and toxicological effects on human health, depending on its dose and chemical form. Recent animal, laboratory, and human studies have shown harmful effects of certain selenium species at specific exposure levels, prompting the need to reassess overall exposure to this element, including that occurring through drinking water, a primary source of inorganic selenium. Drinking water selenium standards worldwide are scarce and existing standards are inconsistent, likely because they have been informed by an incomplete and outdated assessment of the scientific evidence. Incorporating all the available human and laboratory evidence into a precautionary regulatory framework indicates that a drinking water limit of around 5 μg/L of selenium is needed to protect human health, i.e. with an uncertainty factor of 2 versus the lowest adverse effect level observed in human studies, and that higher values may pose unacceptable risks to humans. Despite the rarity of such high levels of selenium in underground and potable waters, coal mining and other sources of environmental pollution as well as geological factors may raise drinking water selenium content above a safe threshold, triggering the need to protect consumers, and to face challenging technological issues for selenium removal, currently under active investigation.

Recent progress in the organoselenium-catalyzed difunctionalization of alkenes

Selenium-based catalysts have recently been utilized to facilitate a variety of new organic transformations, owing to their intrinsic advantages, including low cost, low toxicity, stability in both air and water, and strong compatibility with diverse functional groups. The difunctionalization of alkenes-the process of incorporating two functional groups onto a carbon-carbon double bond-has garnered particular interest within the chemical community owing to its significant applications in organic synthesis. Recently, organoselenium-catalyzed difunctionalization of alkenes has emerged as an ideal and powerful route to obtain high-value vicinal difunctionalized molecules. This review emphasizes recent advancements in this rapidly evolving field, focusing on the scope, limitations, and mechanisms of various reactions.

Products of Selenite/Thiols Interaction Have Reducing Properties, Cleave Plasmid DNA and Decrease Rat Blood Pressure and Tension of Rat Mesenteric Artery

Selenium compounds exert their antioxidant activity mostly when the selenium atom is incorporated into selenoproteins. In our work, we tested the possibility that selenite itself interacts with thiols to form active species that have reducing properties. Therefore, we studied the reduction of 2-(4-carboxyphenyl)-4,5-dihydro-4,4,5,5-tetramethyl-1H-imidazol-1-yloxy-3-oxide radical (•cPTIO), damage of plasmid DNA (pDNA), modulation of rat hemodynamic parameters and tension of isolated arteries induced by products of interaction of selenite with thiols. We found that the products of selenite interaction with thiols had significant reducing properties that could be attributed mainly to the selenide and that selenite had catalytic properties in the access of thiols. The potency of thiols to reduce •cPTIO in the interaction with selenite was cysteine > homocysteine > glutathione reduced > N-acetylcysteine. Thiol/selenite products cleaved pDNA, with superoxide dismutase enhancing these effects suggesting a positive involvement of superoxide anion in the process. The observed •cPTIO reduction and pDNA cleavage were significantly lower when selenomethionine was used instead of selenite. The products of glutathione/selenite interaction affected several hemodynamic parameters including rat blood pressure decrease. Notably, the products relaxed isolated mesenteric artery, which may explain the observed decrease in rat blood pressure. In conclusion, we found that the thiol/selenite interaction products exhibited significant reducing properties which can be used in further studies of the treatment of pathological conditions caused by oxidative stress. The results of decreased rat blood pressure and the tension of mesenteric artery may be perspective in studies focused on cardiovascular disease and their prevention.

Regioselective Access to Substituted Benzothiophenes/furans through Electrochemical Selenium-Promoted Skeletal Rearrangement

An electrochemical strategy for the regioselective construction of seleno-benzothiophenes/furans is reported through electrochemical selenocyclization, followed by Wagner-Meerwein rearrangement. This electro-oxidative tandem process operates under metal-free and external chemical oxidant-free conditions. Advantageously, unprotected homopropargyl alcohols were found to be compatible under the reaction conditions, releasing water and dihydrogen as the biproduct. This methodology reveals good functional group tolerance, allowing a broad spectrum of substrate scopes of up to 87% isolated yield.

Relative bioavailability of selenium yeast, selenomethionine, hydroxyl-selenomethionine and nano-selenium for broilers

Selenium (Se) is an essential trace element for humans and animals. Development and application of new forms of Se sources with lower toxicity and higher bioavailability has been attracting more attention. However, the bioavailabilities of Se from several new Se sources for broilers remain unclear. Therefore, the aim of this study was to assess the relative bioavailabilities of Se from Se yeast (SY), selenomethionine (SM), hydroxyl-selenomethionine (SO) and nano-Se (NS) relative to sodium selenite (SS) for broilers fed a conventional corn-soybean meal diet. A total of 576 one-day-old Arbor Acres commercial male broilers were randomly assigned to 16 treatments with 6 replicate cages per treatment in a completely randomized design involving a 5 (Se sources: SY, SM, SO, NS and SS) × 3 (added Se levels: 0.15, 0.30 and 0.45 mg Se/kg) factorial design of treatments plus 1 (a Se-unsupplemented control) for 21 d. The relative bioavailabilities of Se sources were estimated based on plasma or tissue Se concentrations as well as selenoprotein mRNA expressions and activities in broilers. The results showed that the Se concentrations and glutathione peroxidase (GPX) activities in plasma, liver, breast muscle, pancreas and kidney as well as Se concentration in erythrocytes of broilers, and Gpx1 and Selenop mRNA expressions in pancreas increased linearly (p < 0.03) as added Se level increased. Furthermore, the differences (p < 0.05) among different Se sources were detected for the Se concentrations in liver, breast muscle, pancreas and erythrocytes, GPX activities in pancreas and kidney. Based on slope ratios from the multiple linear regressions of the above indices, the Se bioavailabilities of SY, SM, SO, NS relative to SS (100%) were 78 to 367%, 67.8 to 471%, 57 to 372%, and 45 to 92%, respectively. The results from this study indicated that the Se from SM, SY and SO are more available to broilers than the Se from SS in enhancing the Se concentrations in liver, breast muscle, pancreas and erythrocytes and GPX activity in pancreas, and the Se from SM had the highest while the Se from NS had the lowest relative bioavailability.

Selenocysteine-Activatable Near-Infrared Fluorescent Probe for Screening of Anti-inflammatory Components in Herbs

Inflammation, a central process in numerous diseases, plays a crucial role in hepatic disorders, arthritis, cardiac conditions, and neurodegenerative ailments. Given the lack of effective anti-inflammatory drugs, it is imperative to assess inflammation severity and explore novel therapeutics. Selenocysteine (Sec), a key mediator of selenium's biological function, is closely involved in anti-inflammatory responses. We have synthesized a novel near-infrared fluorescent probe, Sec-BDP, which can image Sec dynamics in vivo with high selectivity and sensitivity. Sec-BDP detects Sec at concentrations as low as 0.085 μM. Utilizing this probe, we visualized Sec levels in cell, zebrafish, and mouse inflammation models, enabling a clear assessment of inflammation severity. To screen for drug candidates, Sec-BDP was integrated with ultrahigh performance liquid chromatography quadrupole time-of-flight mass spectrometry to identify potent anti-inflammatory compounds in Astragalus membranaceus, such as 5-O-methylvisammioside. Imaging of Sec with Sec-BDP provides insights into Sec-related diseases and aids in discovering new treatments. This probe advances selenium biology and promises more targeted therapeutic strategies.

H2Se-evolving bio-heterojunctions promote cutaneous regeneration in infected wounds by inhibiting excessive cellular senescence

Pathogenic infection leads to excessive senescent cell accumulation and stagnation of wound healing. To address these issues, we devise and develop a hydrogen selenide (H2Se)-evolving bio-heterojunction (bio-HJ) composed of graphene oxide (GO) and FeSe2 to deracinate bacterial infection, suppress cellular senescence and remedy recalcitrant infected wounds. Excited by near-infrared (NIR) laser, the bio-HJ exerts desired photothermal and photodynamic effects, resulting in rapid disinfection. The crafted bio-HJ could also evolve gaseous H2Se to inhibit cellular senescence and dampen inflammation. Mechanism studies reveal the anti-senescence effects of H2Se-evolving bio-HJ are mediated by selenium pathway and glutathione peroxidase 1 (GPX1). More critically, in vivo experiments authenticate that the H2Se-evolving bio-HJ could inhibit cellular senescence and potentiate wound regeneration in rats. As envisioned, our work not only furnishes the novel gasotransmitter-delivering bio-HJ for chronic infected wounds, but also gets insight into the development of anti-senescence biomaterials.

Effect of dietary supplementation of selenium-L-methionine on growth, antioxidant capacity and resistance to nitrite stress of spotted seabass (Lateolabrax maculatus) under two rearing water temperatures

A 10-week feeding trial, followed by 24-h nitrite stress, was performed to evaluate the effects of dietary selenium-L-methionine (Se-Met) on growth, Se accumulation, antioxidant capacity, transcripts of selenoproteins and histological changes of muscle as well as resistance to nitrite stress in spotted seabass (Lateolabrax maculatus) reared at optimal (27 °C) and high (33 °C) temperatures. Five experimental diets were formulated to contain 0, 0.9, 1.8, 3.5, and 7.0 mg Se-Met/kg. Each diet was fed to fish (2.60 ± 0.2 g) in two parallel treatments at 27 or 33 °C. The results showed that elevated temperature (33 °C) induced thermal stress in fish, and fish under thermal stress exhibited lower weight gain and hepatosomatic index but a higher condition factor compared to those reared at 27 °C. However, the growth and feed utilisation were promoted in L. maculatus with 0.9 to 3.5 mg/kg Se-Met treatments. The protein and lipid content in the muscle increased with the dietary Se-Met level, and the total Se level in the whole body and muscle showed a linear increase with dietary Se-Met supplementation. Thermal stress changed the histology of the muscle, leading to raised levels of malondialdehyde (MDA), reduced antioxidant parameters in the serum and liver, and a decrease in the transcripts of selenoprotein genes in the muscle. Meanwhile, increased antioxidant capacity of serum and liver and up-regulated transcripts of selenoprotein of muscle were observed in L. maculatus reaching a maximum with 3.5 mg Se-Met/kg treatment. After 24 h of nitrite stress, thermal stress exacerbated oxidative damage caused by nitrite stress in L. maculatus. In contrast, dietary Se-Met enhanced the resistance to nitrite stress of L. maculatus fed with Se-Met enriched diets containing 0.9 to 1.8 mg Se-Met/kg. Based on the effects of dietary Se-Met on the growth, antioxidant capacity and resistance to nitrite stress of L. maculatus, this study suggests that the optimal range of Se-Met supplementation in L. maculatus diets is 1.80 to 2.39 mg Se-Met/kg of diet at 27 °C and 1.80 to 4.46 mg Se-Met/kg of diet at 33 °C.

Phenacylselenoesters allow facile selenium transfer and hydrogen selenide generation

Hydrogen selenide (H2Se) is a precursor to several selenium-containing biomolecules and is emerging as an important redox-active species in biology, with yet to be completely characterized roles. Tools that reliably generate H2Se are key to achieving a better understanding of selenium biology. Here, we report the design, synthesis and evaluation of phenacylselenoesters as sources of H2Se. These compounds are prepared in two steps from commercial compounds, some are crystalline solids, and all are stable during storage. In the presence of esterase and a thiol in pH 7.4 buffer, these compounds produce H2Se, with half-lives of 5-20 min. We developed a colorimetric assay for the detection of gaseous H2Se by trapping it as zinc selenide (ZnSe), which is then converted to lead selenide (PbSe), which serves as a convenient visual indicator for this gas. The major organic products that are formed in nearly quantitative yields are relatively benign ketones and carboxylic acids. We provide evidence for these donors producing a thioselenide, a key intermediate in biological selenium metabolism. Finally, we compared sulfur and selenium transfer, both critical processes in cells. Phenacylthiol is relatively stable to cleavage by a thiol, and requires a sulfurtransferase enzyme to produce a persulfide and H2S. By contrast, the selenium analogue reacted with a thiol in the absence of this enzyme to produce H2Se. This result underscores the greater lability of the C-Se bond as compared with a C-S bond, and may have implications in biological selenium transfer. Together, phenacylselenoesters are easy to prepare, stable and generate H2Se under mild and biocompatible conditions. We anticipate that these will be valuable additions to the growing selenium redox toolbox.

Surface different charge ligands for modulating selenium nanoparticles formation and activating the interaction with proteins for effective anti-Herpes simplex virus l infection

Selenium-based nanoparticles exhibit antiviral activity by directly modulating immune function. Despite recent promising developments in utilizing selenium nanoparticles (Se NPs) against viral infections, the impact of surface ligand charge on the conformation and interaction with viral proteins, as well as the effectiveness of Se NPs in anti-Herpes simplex virus 1 (HSV-1) infection remains unexplored. In this study, three types of selenium nanoparticles (CTAB-Se, PVP-Se, SDS-Se) with distinct surface charges were synthesized by modifying the surface ligands. We found that apart from differences in surface charge, the size, morphology, and crystal structure of the three types of Se NPs were similar. Notably, although the lipophilicity and cellular uptake of SDS-Se with a negative charge were lower compared to positively charged CTAB-Se and neutrally charged PVP-Se, SDS-Se exhibited the strongest protein binding force during interaction with HSV-1. Consequently, SDS-Se demonstrated the most potent anti-HSV-1 activity and safeguarded normal cells from damage. The mechanistic investigation further revealed that SDS-Se NPs effectively inhibited the proliferation and assembly of HSV-1 by powerfully suppressing the key genes and proteins of HSV-1 at various stages of viral development. Hence, this study highlights the significant role of surface ligand engineering in the antiviral activity of Se NPs, presenting a viable approach for synthesizing Se NPs with tailored antiviral properties by modulating surface charge. This method holds promise for advancing research on the antiviral capabilities of Se NPs.

Silver-Mediated Acetoxyselenylation of Alkynes: Mild Stereoselective Access to Bifunctional Alkenes

Herein, we report a AgF-mediated regio- and stereoselective acetoxyselenylation of terminal/internal alkynes from iodobenzene dicarboxylate [PhI(OCOR)2] and diorganyl diselenides via multiple-site functionalization to afford β-selenyl enol esters in good yields. Alkynes derived from bioactive molecules, such as l(-)-borneol, l-menthol, and acyne oxalate, are also suitable for this transformation and afford the expected compounds.

Optimizing food waste bioconversion with sodium selenite-enhanced Lucilia sericata maggots: a sustainable approach for chicken feed production and heavy metal mitigation

Recycling food waste by feeding it to insects can result in the continuous production of high-quality animal feed protein and organic fertilizer. However, the bioconversion efficiency and safety of using insects as feed protein for animal breeding are important factors limiting the development of this technology. Therefore, we aimed to optimize the efficiency of bioconversion of food waste using Lucilia sericata maggot (LSM). Sodium selenite (SS) was used to improve the quality and safety of each trophic-level organism. The results showed that an SS concentration of 15 mg kg-1 w.w. in the food waste culture substrate (SS15), the yield and quality of the obtained LSMs were optimal. The total selenium (Se) content of LSMs was 82.4 ± 1.16 mg kg-1 d.w., and non-inorganic Se accounted for 96.4% ± 2.01% of the total Se content. Additionally, the conversion efficiency of food waste was 18.7% higher than that in the control group (p < 0.05). When SS15 was used to raise maggots as a protein substitute for fish meal (commercial feed), the weight of the chickens and the crude protein content were 1.09-1.26 times and 1.09-1.13 times, respectively (p < 0.05), in comparison with the corresponding findings obtained with the use of ordinary maggots and commercial feed. In this group, glutathione peroxidase, superoxide dismutase, catalase, and immunoglobulin A and G activities were significantly higher than those obtained with the other feeds (p < 0.05). During this cyclic utilization process, the total Se content in chickens (0.31 ± 0.05 mg kg-1 w.w. in the breast, 0.19 ± 0.01 mg kg-1 w.w. in the leg, and 0.57 ± 0.01 mg kg-1 w.w. in the liver) significantly increased (p < 0.05). Meanwhile, the Cu and Zn contents in the LSMs and chickens increased, whereas cadmium, lead, chromium, and nickel absorption was inhibited (p < 0.05). Health risk assessment based on the levels of Se and heavy metals showed that Se-enriched chickens produced using this method can be safely consumed.

Effects of Trace Mineral Source on Growth Performance, Antioxidant Activity, and Meat Quality of Pigs Fed an Oxidized Soy Oil Supplemented Diet

This study investigates the effects of oil quality and trace mineral source on the growth performance, antioxidant activity, and meat quality of growing-finishing pigs. A total of 180 crossbred pigs (Duroc × Landrace × Large White [64.4 ± 1.95]) were randomly allocated five dietary treatments based on body weight (BW) and sex in a 30 d trial. Pigs were fed five diets: (i) fresh soy oil + inorganic trace minerals (ITMs) + inorganic selenium (FISI), (ii) oxidized soy oil + ITMs + inorganic selenium (OISI), (iii) fresh soy oil + ITMs + selenium yeast (FISY), (iv) oxidized soy oil + ITMs + selenium yeast (OISY), and (v) oxidized soy oil + organic trace minerals (OTMs) + selenium yeast (OOSY). Each dietary treatment included six replicates and six pigs per replicate (three barrows and three gilts). Feeding OISI resulted in lower average daily gain (ADG) and dressing percentage (p < 0.05). The OOSY group had a higher dressing percentage and activities of serum CAT and GSH-Px in growing-finishing pigs (p < 0.05). In addition, the relative abundance of Campylobacterota in the colonic digesta varied with the quality of soy oil and source of trace minerals (p < 0.05), but no significant differences in short-chain fatty acid concentrations were observed among all dietary groups. In conclusion, adding oxidized soy oil to the diet negatively impacted the ADG and dressing percentage of growing-finishing pigs, and replacing ITMs with OTMs and SY alleviated these negative impacts. A combination of OTMs and SY can support antioxidant capacity to mitigate the negative impacts of oxidized oil on the growth performance and dressing percentage of growing-finishing pigs.

Benzoimidazolyl Organoseleniums: Antioxidant Activity and Catalysts for Selective Iodination of Arenes and Nitro-Michael Reaction

Here, the synthesis and catalytic activities of benzoimidazole-derived organoselenium compounds have been explored. The synthesized bis(2-benzoimidazolyl) diselenide, having increased Lewis acidity on the selenium center, outperforms simple phenyl and N-phenyl benzamide-based diselenides when compared for thiol peroxidase hydrogen peroxide decomposing antioxidant activity with a reduction rate of 18.6 ± 1.9 μM/s. The synthesized diselenide also acted as an efficient catalyst for the activation of N-iodo-succinimide toward the regioselective, monoiodination of electron-rich arenes and activation of nitro-alkene for nitro-Michael reactions for the first time.

Mendelian randomization analyses explore the effects of micronutrients on different kidney diseases

Background

The impact of micronutrients, including vitamins and minerals, on different kidney diseases has been reported in some observational studies; however, their causal relationship remains uncertain. We aimed to ascertain the causal genetic relationships between micronutrients and different kidney diseases using the Mendelian randomization (MR) method.

Methods

Instrumental variables (IVs) for genetically predicting calcium (Ca), iron (Ir), Zinc (Zn), selenium (Se), copper (Cu), vitamin D (Vit D), and vitamin C (Vit C) levels in humans were obtained, and a bidirectional two-sample MR was used to examine potential associations between the levels of these seven micronutrients and the risk of seven different kidney diseases including hypertensive renal disease, diabetic nephropathy, IgA nephropathy, membranous nephropathy, cystic nephropathy, chronic kidney disease (CKD), and chronic tubulo-interstitial nephritis. Five different MR analyses were conducted, with the main method being the inverse variance-weighted (IVW) method. Moreover, sensitivity analyses were performed to assess heterogeneity and potential pleiotropy.

Results

The IVW method revealed that Ca levels were associated with a decreased risk of hypertensive renal disease (OR = 0.61, 95% CI: 0.40-0.93, p-value = 0.022), and Se levels were associated with a decreased risk of hypertensive renal disease (OR = 0.72, 95% CI: 0.53-0.99, p-value = 0.040), diabetic nephropathy (OR = 0.83, 95% CI: 0.73-0.93, p-value = 0.002), and CKD (OR = 0.87, 95% CI: 0.77-0.99, p-value = 0.028). Conversely, Vit D levels were associated with an increased risk of polycystic kidney disease (OR = 1.76, 95% CI: 1.15-2.69, p-value = 0.0095). In addition, no potential causal relationship was found between vitamin C levels, iron levels, zinc levels, and copper levels and different kidney diseases. Meanwhile, inverse Mendelian randomization showed no potential causal relationship between different chronic kidney diseases and micronutrients. The Cochrane's Q test, MR-Egger regression, and MR-PRESSO did not suggest heterogeneity and pleiotropy, providing evidence of the validity of the MR estimates.

Conclusion

Our results indicate a cause-and-effect connection between micronutrients and certain kidney diseases, but additional study is required to provide more conclusive evidence. This research has the potential to assist clinicians in managing the consumption of specific micronutrients among individuals with chronic kidney diseases, as well as in promoting disease prevention among both healthy populations and those who are susceptible to chronic underlying conditions.

Electrochemically chalcogenative annulation enabled construction of functionalized saturated N-heterocycles

An efficient chalcogenative annulation strategy for constructing functionalized saturated N-heterocycles from unactivated alkenes with dichalcogenides under electrochemical conditions has been presented. This protocol is applicable to mono-, di- or tri-substituted alkenes, providing a straightforward pathway to aziridines, azetidines, pyrrolidines, and piperidines with high regioselectivity. Moreover, the strategy is qualified to realize the oxychalcogenation of alkenes as well.

Fast Intramolecular Thiol-Activated Arylselenoamides Provide Access to Triggered, Fluorogenic H2Se Donors

H2Se is the precursor for the biosynthesis of selenocompounds and is a potential gasotransmitter. Chemical tools for H2Se delivery and detection are important for Se-related biology research. Key challenges in the field include developing compound platforms that are triggered to release H2Se under various stimuli and developing fluorogenic donors that allow for real-time tracking of H2Se delivery. Here we report a new general platform for triggered H2Se donors based on controllable deprotection of a thiol, which can quickly activate an intramolecular arylselenoamide (t1/2 < 1 min) to release H2Se efficiently. Furthermore, we leverage this platform to develop the first examples of fluorogenic H2Se donors, which can be used to monitor H2Se release by fluorescence in real time. We anticipate that the well-defined donation chemistries will significantly advance the development of H2Se donors and stimulate further in-depth studies of H2Se biomedicine.

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.

Generation of Thiosulfate, Selenite, Dithiosulfite, Perthionitrite, Nitric Oxide, and Reactive Chalcogen Species by Binuclear Zinc(II)-Chalcogenolato/-Polychalcogenido Complexes

A comparative bioinspired reactivity study of new binuclear Zn(II) complexes featuring coordinated thiolate, selenolate, trisulfide and diselenide in relation with (i) the generation of reactive sulfur/selenium species (RSS/RSeS), (ii) the oxygen dependent oxidation and disproportionation of polysulfide (Sn2-) to produce sulfite (SO32-), thiosulfate (S2O32-) and sulfide (S2-) by sulfur oxygenase reductase (SOR), and (iii) the reaction of Sn2- with nitrite (NO2-) to generate thionitrite (SNO-), perthionitrite (SSNO-) and nitric oxide (NO), is presented. The binuclear Zn(II)-thiolate/selenolate complexes could react with elemental sulfur to generate RSS/RSeS while similar reactions involving elemental selenium could not generate RSeS. The dizinc(II)-S3 and the dizinc(II)-Se2 complexes could react with dioxygen (O2) to generate binuclear Zn(II) complexes featuring coordinated thiosulfate (S2O32-) and selenite (SeO32-), respectively. Finally, unlike the nonreactive nature of the dizinc(II)-Se2 complex toward NO2-, reaction of the dizinc(II)-S3 complex with NO2- produced a new binuclear Zn(II) complex featuring a coordinated dithiosulfite (S3O2-) along with the formation of perthionitrite (SSNO-), of which the latter subsequently produced nitric oxide (NO) and S42-. The present work, thus, demonstrates the comparative reactivity of a series of binuclear Zn(II)-chalcogenolato/-polychalcogenido complexes for the generation of S2O32-, SeO32-, S3O2-, SSNO-, NO and RSS/RSeS.

Liposomes as selenium nanocarriers for foliar application to wheat plants: A biofortification strategy

In the present work, liposomes have been used as nanocarriers in the biofortification of wheat plants with selenium (Se) through foliar application. Liposomal formulations were prepared using 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and Phospholipon®90H (P90H) (average size <100 nm), loaded with different concentrations of inorganic Se (selenite and selenate) and applied twice to the plants in the stage of vegetative growth. Liposomes enhanced Se uptake by wheat plants compared to direct application. The highest Se enrichment was achieved using the phospholipid DPPC and a concentration of 1000 μmol·L-1 of Se without affecting the biomass, chlorophylls, carotenoids, and the concentration of mineral nutrients of the plants. The chemical speciation of Se in the plants was further investigated by X-ray absorption spectroscopy (XAS). The results from XAS spectra revealed that most of the inorganic Se was transformed to organic Se and that the use of liposomes influenced the proportion of C-Se-C over C-Se-Se-C species.

Isosteric Replacement of Sulfur to Selenium in a Thiosemicarbazone: Promotion of Zn(II) Complex Dissociation and Transmetalation to Augment Anticancer Efficacy

We implemented isosteric replacement of sulfur to selenium in a novel thiosemicarbazone (PPTP4c4mT) to create a selenosemicarbazone (PPTP4c4mSe) that demonstrates potentiated anticancer efficacy and selectivity. Their design specifically incorporated cyclohexyl and styryl moieties to sterically inhibit the approach of their Fe(III) complexes to the oxy-myoglobin heme plane. Importantly, in contrast to the Fe(III) complexes of the clinically trialed thiosemicarbazones Triapine, COTI-2, and DpC, the Fe(III) complexes of PPTP4c4mT and PPTP4c4mSe did not induce detrimental oxy-myoglobin oxidation. Furthermore, PPTP4c4mSe demonstrated more potent antiproliferative activity than the homologous thiosemicarbazone, PPTP4c4mT, with their selectivity being superior or similar, respectively, to the clinically trialed thiosemicarbazone, COTI-2. An advantageous property of the selenosemicarbazone Zn(II) complexes relative to their thiosemicarbazone analogues was their greater transmetalation to Cu(II) complexes in lysosomes. This latter effect probably promoted their antiproliferative activity. Both ligands down-regulated multiple key receptors that display inter-receptor cooperation that leads to aggressive and resistant breast cancer.

Reprogramming Tumor-Associated Macrophages with a Se-Based Core-Satellite Nanoassembly to Enhance Cancer Immunotherapy

Tumor-associated macrophages (TAMs), as the most prevalent immune cells in the tumor microenvironment, play a pivotal role in promoting tumor development through various signaling pathways. Herein, we have engineered a Se@ZIF-8 core-satellite nanoassembly to reprogram TAMs, thereby enhancing immunotherapy outcomes. When the nanoassembly reaches the tumor tissue, selenium nanoparticles and Zn2+ are released in response to the acidic tumor microenvironment, resulting in a collaborative effort to promote the production of reactive oxygen species (ROS). The generated ROS, in turn, activate the nuclear factor κB (NF-κB) signaling pathway, driving the repolarization of TAMs from M2-type to M1-type, effectively eliminating cancer cells. Moreover, the nanoassembly can induce the immunogenic death of cancer cells through excess ROS to expose calreticulin and boost macrophage phagocytosis. The Se@ZIF-8 core-satellite nanoassembly provides a potential paradigm for cancer immunotherapy by reversing the immunosuppressive microenvironment.

Visible-light induced selenocyclization of 2-ethynylanilines under ambient conditions: simple FeBr3 as a dual-functional catalyst

We report herein a visible-light induced, Fe-catalyzed selenocyclization of 2-ethynylanilines with diselenides under ambient conditions, employing ethyl acetate as a benign solvent with no stoichiometric additive required. The simple iron salt FeBr3 serves as both a photo-induced LMCT (Ligand-to-Metal Charge Transfer) catalyst and a Lewis acid catalyst to promote the desired transformation in a sustainable manner, enabling the facile synthesis of diverse 3-selenylindoles with extended substitution patterns. Moreover, gram-scale reactions and late-stage functionalization of bioactive molecules further highlight the synthetic practicality of this method.

Selenium Species in Diabetes Mellitus Type 2

Selenium is an important trace element for humans and animals as it plays a key role in several major metabolic pathways. Several studies were conducted to better understand the role of selenium against diabetes mellitus (DM), particularly type 2 (T2DM), but the obtained conclusions are contradictory. A simple linear relationship does not exist between the risk of T2DM and selenium levels but is best represented in a dose-dependent manner, getting often the U-graph. This relation also depends on selenium chemical forms that are present in a diet or supplements. Both too low and too high selenium intakes could increase the risk of diabetes. Moreover, the baseline status of Se should be taken into consideration to avoid over-supplementation. The focus of this brief overview is to report the recent updates concerning selenium participation in diabetes mellitus.

Response surface methodology optimizes selenium inhibition of prostate cancer PC-3 cell viability

BACKGROUND

The rising incidence of prostate cancer in the U.S. necessitates innovative therapeutic approaches to this disease. Though extensive research has studied Selenium as an anticarcinogen against prostate cancer, results have varied due to overlooked experimental confounds. Recent studies have identified differential effects of various selenium compounds on prostate cancer cells. This study leverages Mixture Design Response Surface Methodology to characterize the ideal combination of select Se forms against the PC-3 prostate cancer cell line.

METHODS

The PC-3 cell line was chosen as a model for its representation of advanced-stage malignancy. Three Se compounds-sodium selenite, methylseleninic acid, and nano-selenium-were selected for their promising antineoplastic potential. Nano-Se particles were synthesized and subsequently characterized by transmission electron microscopy. Cells were cultured, treated with Se compounds, and assessed for viability using an Alamar Blue Assay. IC50 values of individual Se compounds were determined, and treatment combinations evaluated. In collaboration with statical modeling experts, MDRSM was utilized to optimize Se compound combinations.

RESULTS

Absolute IC50 values were identified for methylseleninic acid (5.01 μmol/L), sodium selenite (13.8 μmol/L), and nano-selenium (14.6 μmol/L). Combining methylseleninic acid and sodium selenite resulted in only 5% PC-3 cell viability, whereas individual treatments reduced viability by approximately 45%. Among the tested mixtures, the 50:50 combination of MSA and sodium selenite most effectively decreased PC-3 cell viability. Regression analysis indicated the special cubic model had a strong fit (multiple r² = 0.9853), predicting maximum cell viability reduction from the methylseleninic acid and selenite mixture.

CONCLUSION

The specific form of Selenium plays a pivotal role in determining its physiological effects and therapeutic potential against prostate cancer. All three selenium compounds showed variable antineoplastic effects, with a 50:50 mixture of methylseleninic acid and selenite exhibiting optimal results. Nano-selenium, when combined with selenite, showed no additive effect, implying a shared mechanism of action. Our research underscores the critical need to consider Se compound forms as distinct entities in prostate cancer treatment and encourages further exploration of Se compounds against prostate cancer.

Deuterium labeling improves the therapeutic index of 3,3'-diselenodipropionic acid as an anticancer agent: insights from redox reactions

3,3'-Diselenodipropionic acid (DSePA), a selenocystine derivative, has been previously reported as an oral supplement for anticancer/radio-modulation activities. The present study is focused on devising a strategy to synthesize and characterize the deuterated derivative of DSePA and on understanding the effect of deuteration on its therapeutic index by comparing its cytotoxicity in cancerous versus non-cancerous cell types. In this context, the synthesis of 3,3'-diselenodipropionic acid-D8 (D-DSePA) was accomplished in ∼42% yield. Further, the results clearly established that the deuteration of DSePA significantly reduced its cytotoxicity in non-cancerous cell types while retaining its cytotoxicity in cancerous cell lines. Together, D-DSePA displayed a ∼5-fold higher therapeutic index than the non-deuterated derivative for anticancer activity. The biochemical and NMR studies confirmed that the better biocompatibility of D-DSePA than its non-deuterated derivative in non-cancerous cells was due to its ability to undergo slower redox reactions and to cause lesser inhibition of intracellular redox enzymes.

Nonheme binuclear transition metal complexes with hydrosulfide and polychalcogenides

The intriguing chemistry of chalcogen (S, Se)-containing ligands and their capability to bridge multiple metal centres have resulted in a plethora of reports on transition metal complexes featuring hydrosulfide (HS-) and polychalcogenides (En2-, E = S, Se). While a large number of such molecules are strictly organometallic complexes, examples of non-organometallic complexes featuring HS- and En2- with N-/O-donor ligands are relatively rare. The general synthetic procedure for the transition metal-hydrosulfido complexes involves the reaction of the corresponding metal salts with HS-/H2S and this is prone to generate sulfido bridged oligomers in the absence of sterically demanding ligands. On the other hand, the synthetic methods for the preparation of transition metal-polychalcogenido complexes include the reaction of the corresponding metal salts with En2- or the two electron oxidation of low-valent metals with elemental chalcogen, often at an elevated temperature and/or for a long time. Recently, we have developed new synthetic methods for the preparation of two new classes of binuclear transition metal complexes featuring either HS-, or Sn2- and Sen2- ligands. The new method for the synthesis of transition metal-hydrosulfido complexes involved transition metal-mediated hydrolysis of thiolates at room temperature (RT), while the method for the synthesis of transition metal-polychalcogenido complexes involved redox reaction of coordinated thiolates and exogenous elemental chalcogens at RT. An overview of the synthetic aspects, structural properties and intriguing reactivity of these two new classes of transition metal complexes is presented.

Bioinspired Selenium-Nitrogen Exchange (SeNEx) Click Chemistry Suitable for Nanomole-Scale Medicinal Chemistry and Bioconjugation

Click chemistry is a powerful molecular assembly strategy for rapid functional discovery. The development of click reactions with new connecting linkage is of great importance for expanding the click chemistry toolbox. We report the first selenium-nitrogen exchange (SeNEx) click reaction between benzoselenazolones and terminal alkynes (Se-N to Se-C), which is inspired by the biochemical SeNEx between Ebselen and cysteine (Cys) residue (Se-N to Se-S). The formed selenoalkyne connection is readily elaborated, thus endowing this chemistry with multidimensional molecular diversity. Besides, this reaction is modular, predictable, and high-yielding, features fast kinetics (k2≥14.43 M-1 s-1), excellent functional group compatibility, and works well at miniaturization (nanomole-scale), opening up many interesting opportunities for organo-Se synthesis and bioconjugation, as exemplified by sequential click chemistry (coupled with ruthenium-catalyzed azide-alkyne cycloaddition (RuAAC) and sulfur-fluoride exchange (SuFEx)), selenomacrocycle synthesis, nanomole-scale synthesis of Se-containing natural product library and DNA-encoded library (DEL), late-stage peptide modification and ligation, and multiple functionalization of proteins. These results indicated that SeNEx is a useful strategy for new click chemistry developments, and the established SeNEx chemistry will serve as a transformative platform in multidisciplinary fields such as synthetic chemistry, material science, chemical biology, medical chemistry, and drug discovery.

A screening for optimal selenium enrichment additives for selenium-enriched fish production: Application of a HPLC-ICP-MS method

The production of selenium-enriched fish contributes to alleviating selenium deficiency for humans. In this study, selenium nanoparticles (SeNPs) comparable in bioavailability to selenomethionine (SeMet), increased SeMet content in O. macrolepis (Onychostoma macrolepis) muscle. Additionally, dietary SeNPs significantly enhanced selenocysteine (SeCys2) and methylselenocysteine (MeSeCys) levels in O. macrolepis muscle. The effect of SeNPs on selenium speciation in grass carp muscle was consistent with O. macrolepis results. SeCys2 and MeSeCys showed antioxidant capacity in HEK293T cells, indicating enhanced health benefits of Se-enriched fish produced using SeNPs. Furthermore, the addition of 0.3 mg/kg SeNPs significantly improved the flesh quality of O. macrolepis by reducing the content of crude fat and heavy metals, as well as increasing the levels of crude protein, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and the ratio of n-3/n-6 polyunsaturated fatty acids (PUFAs). Therefore, selenium-enriched fish produced from SeNPs is a good source for improving human dietary selenium intake.

Preoperative serum selenium predicts acute kidney injury after adult cardiac surgery

BACKGROUND

The relationship between serum selenium (Se) and acute kidney injury after adult cardiac surgery (CSA-AKI) remains controversial. This study aimed to investigate the association of preoperative Se level with incident CSA-AKI.

METHOD AND RESULTS

A retrospective cohort study was conducted on patients who underwent cardiac surgery. The primary outcome was incident CSA-AKI. Multivariable logistic regression models and natural cubic splines were used to estimate the association of Se levels and primary outcome. A total of 453 patient with a mean age of 62.97 years were included. Among all patients, 159 (35.1%) incident cases of CSA-AKI were identified. The level of preoperative Se concentration in patients with CSA-AKI was significant lower than that in patients without CSA-AKI. The higher preoperative Se level was significantly associated with decreased risk of CSA-AKI (adjusted OR 0.91, 95% CI: 0.87-0.99). Dose-response relationship curve revealed a nearly L-shape correlation between serum Se selenium levels and incident CSA-AKI.

CONCLUSION

Our study suggested that a higher level of serum Se was significantly associated with lower risk of CSA-AKI. Further prospective studies are needed to clarify the causal relationship between serum Se level and incident CSA-AKI.

In-situ synthesis of quantum dots in the nucleus of live cells

The cell nucleus is the main site for the storage and replication of genetic material, and the synthesis of substances in the nucleus is rhythmic, regular and strictly regulated by physiological processes. However, whether exogenous substances, such as nanoparticles, can be synthesized in situ in the nucleus of live cells has not been reported. Here, we have achieved in-situ synthesis of CdSxSe1-x quantum dots (QDs) in the nucleus by regulation of the glutathione (GSH) metabolic pathway. High enrichment of GSH in the nucleus can be accomplished by the addition of GSH with the help of the Bcl-2 protein. Then, high-valence Se is reduced to low-valence Se by glutathione-reductase-catalyzed GSH, and interacts with the Cd precursor formed through Cd and thiol-rich proteins, eventually generating QDs in the nucleus. Our work contributes to a new understanding of the syntheses of substances in the cell nucleus and will pave the way for the development of advanced 'supercells'.

Selenium nanoparticles in aquaculture: Unique advantages in the production of Se-enriched grass carp (Ctenopharyngodon idella)

The production of selenium-enriched fish can contribute to alleviating selenium deficiency in human diets. However, it is still unclear which selenium source, as an additive, can efficiently and cost-effectively produce high-quality selenium-enriched fish. This study evaluated the effects of selenium nanoparticles (SeNP), selenite, and selenomethionine (SeMet) on the growth, antioxidant capacity, selenium content, selenium speciation, and meat quality of grass carp. Ten diets were prepared, including a basal diet (BD) and three concentrations (0.1, 0.3, and 0.9 mg/kg) of SeNP, selenite, and SeMet. A total of 600 fish (250.79 ± 1.57 g) were randomly assigned to 30 tanks (3 tanks/group). Fish were fed the experimental diet three times daily for 60 d. In this study, SeNP most significantly promoted the growth and antioxidant capacity of grass carp, with 0.3 mg/kg SeNP identified as the optimal additive concentration. Additionally, SeNP demonstrated equally excellent bioavailability as SeMet and significantly increased the content of SeMet in grass carp (Ctenopharyngodon idella) muscle. Furthermore, compared to SeMet and selenite, dietary SeNP could more significantly enhance the content of selenocysteine (SeCys2) and methylselenocysteine (MeSeCys) in grass carp muscle tissue. In addition, we have demonstrated that SeCys2 and MeSeCys promote apoptosis of cancer cells (HeLa) through the mitochondrial apoptotic pathway (involving Bax and Bcl-2). Furthermore, as an additive, 0.3 mg/kg SeNP significantly improved the flesh quality of grass carp by reducing crude fat and heavy metal content, as well as increasing the levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and the ratio of n-3/n-6 polyunsaturated fatty acid (PUFA). In summary, SeNP is the most suitable additive for producing selenium-enriched fish.

Synthesis of New Chiral β-Carbonyl Selenides with Antioxidant and Anticancer Activity Evaluation-Part I

A series of unsymmetrical phenyl β-carbonyl selenides with o-amido function substituted on the nitrogen atom with chiral alkyl groups was obtained. The compounds form a series of enantiomeric and diastereomeric pairs and present the first examples of this type of chiral Se derivatives. All obtained selenides were further evaluated as antioxidants and anticancer agents to define the influence of the particular stereochemistry of the attached functional groups on the bioactivity of the molecules. The highest H2O2 reduction potential was observed for N-(cis-2-hydroxy-1-indanyl)-2-((2-oxopropyl)selanyl)benzamide, and the best radical scavenging properties for N-(-1-hydroxy-2-butanyl)-2-((2-oxopropyl)selanyl)benzamide. Also, both enantiomers of the N-(1-hydroxy-2-butanyl) selenide expressed the highest cytotoxic potential towards human promyelocytic leukemia HL-60 cell line with similar IC50 values 14.4 ± 0.5 and 16.2 ± 1.1 µM, respectively. On the other hand, breast cancer cell line MCF-7 was most sensitive to N-((R)-(-)-1-hydroxy-2-butanyl)- 2-((2-oxopropyl)selanyl)benzamide (IC50 of 35.7 ± 0.6 µM). The structure-activity dependence of the obtained Se derivatives was discussed, and the most potent compounds were selected.

Adherence to the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diet and exposure to selenium species: A cross-sectional study

Selenium is a trace element found in many chemical forms. Selenium and its species have nutritional and toxicologic properties, some of which may play a role in the etiology of neurological disease. We hypothesized that adherence to the Mediterranean-Dietary Approach to Stop Hypertension Intervention for Neurodegenerative Delay (MIND) diet could influence intake and endogenous concentrations of selenium and selenium species, thus contributing to the beneficial effects of this dietary pattern. We carried out a cross-sectional study of 137 non-smoking blood donors (75 females and 62 males) from the Reggio Emilia province, Northern Italy. We assessed MIND diet adherence using a semiquantitative food frequency questionnaire. We assessed selenium exposure through dietary intake and measurement of urinary and serum concentrations, including speciation of selenium compound in serum. We fitted non-linear spline-based regression models to investigate the association between MIND diet adherence and selenium exposure concentrations. Adherence to the MIND diet was positively associated with dietary selenium intake and urinary selenium excretion, whereas it was inversely associated with serum concentrations of overall selenium and organic selenium, including serum selenoprotein P-bound selenium, the most abundant circulating chemical form of the metalloid. MIND diet adherence also showed an inverted U-shaped relation with inorganic selenium and particularly with its hexavalent form, selenate. Our results suggest that greater adherence to the MIND diet is non-linearly associated with lower circulating concentrations of selenium and of 2 potentially neurotoxic species of this element, selenoprotein P and selenate. This may explain why adherence to the MIND dietary pattern may reduce cognitive decline.

First-in-Class Selenium-Containing Potent Serotonin Receptor 5-HT6 Agents with a Beneficial Neuroprotective Profile against Alzheimer's Disease

Alzheimer's disease (AD) has a complex and not-fully-understood etiology. Recently, the serotonin receptor 5-HT6 emerged as a promising target for AD treatment; thus, here a new series of 5-HT6R ligands with a 1,3,5-triazine core and selenoether linkers was explored. Among them, the 2-naphthyl derivatives exhibited strong 5-HT6R affinity and selectivity over 5-HT1AR (13-15), 5-HT7R (14 and 15), and 5-HT2AR (13). Compound 15 displayed high selectivity for 5-HT6R over other central nervous system receptors and exhibited low risk of cardio-, hepato-, and nephrotoxicity and no mutagenicity, indicating its "drug-like" potential. Compound 15 also demonstrated neuroprotection against rotenone-induced neurotoxicity as well as antioxidant and glutathione peroxidase (GPx)-like activity and regulated antioxidant and pro-inflammatory genes and NRF2 nuclear translocation. In rats, 15 showed satisfying pharmacokinetics, penetrated the blood-brain barrier, reversed MK-801-induced memory impairment, and exhibited anxiolytic-like properties. 15's neuroprotective and procognitive-like effects, stronger than those of the approved drug donepezil, may pave the way for the use of selenotriazines to inhibit both causes and symptoms in AD therapy.