Selenium-Containing Proteins/Peptides from Plants: A Review on the Structures and Functions

Novel cationic dihydropyrrol-2-one compounds as antimicrobial agents and quorum sensing inhibitors

Antimicrobial resistance has grown to become a global crisis consistently participating in the death of millions worldwide and accumulating costs on healthcare. Quorum sensing inhibition is a new alternative antimicrobial strategy that has been gaining attention due to its ability to suppress the resistance of Pseudomonas aeruginosa (PA). This approach shows great potential in overcoming bacterial resistance and could provide a much needed substitute to conventional antibiotics in the future. PA has 3 main quorum sensing systems of which the Las system has been identified to be the most viable therapeutic target. In this study, we report the synthesis of a library of novel broad-spectrum quorum sensing inhibitors from the dihydropyrrol-2-one scaffold to form urea and imidazolium analogues. Molecular docking was performed in parallel to synthesis to aid design. It also confirmed that the molecules comfortably occupy the ligand binding domain in addition to potential key interactions commonly present in LasR inhibitors. As predicted, these compounds displayed low bactericidal effects against P. aeruginosa with most compounds exhibiting MIC of >250 μM, while maintaining moderate activity towards Escherichia coli with the most potent compound having an MIC of 32 μM. The greatest bactericidal effects were present on Staphylococcus aureus with the thiourea based molecule 10c showed the highest antibacterial activity with MIC of 16 µM. Furthermore, several molecules displayed highly potent quorum sensing inhibitory activity with compounds 10g and 9e both demonstrating over 70 % inhibition respectively of the LasR system at 16 µM. These compounds also expressed inhibition of pyocyanin within P. aeruginosa and haemolytic assay indicates a low level of cell lysis and hence low toxicity of the compounds, further demonstrating the potential of these novel compounds.

Research Progress on Anti-Hyperlipidemia Peptides Derived from Foods

Hyperlipidemia is a metabolic disorder in which cholesterol (TC) and triglycerides (TGs) in the blood exceed the normal physiological levels. The incidence of the condition has continued to rise in recent years, posing a serious threat to public health. Its clinical treatment mainly relies on drug interventions, such as statins, fibrate, and niacin. Although these drugs have shown some efficacy in the treatment of hyperlipidemia, their adverse effects cannot be ignored. In contrast, naturally derived peptides have gradually become potential candidates for the prevention and treatment of hyperlipidemia due to their strong anti-hyperlipidemic activity and safety; examples of such peptides include those from dairy products, grains, legumes, and seafood. This review systematically summarizes peptides with anti-hyperlipidemic activity and analyzes their mechanisms of action, providing a theoretical basis for further research. In addition, we also outline some challenges facing the application of peptides, hoping to prevent hyperlipidemia and reduce its incidence by encouraging the consumption of foods rich in anti-hyperlipidemia peptides.

Effects of different drying methods on the structure, bioaccessibility, and bioavailability of selenium-enriched peptides from soybean sprouts

Selenium-enriched peptides (SePPs) were isolated from Se-enriched soybean sprouts as the selenium (Se) supplement. The preparation of SePPs was optimised, and their Se content, stability during drying, and absorption properties, were examined. The maximum in vitro antioxidant activity of SePPs was achieved after 5 h of alcalase, at 50 °C, pH 9, 3 % substrate concentration, and 5 % enzyme concentration. 58 peptides containing SeMet or SeCsy were found. Following different drying methods, the Se content dropped, and the cross-linked SePPs produced by freeze-drying had higher hydrophobicity, reduced free sulfhydryl concentration, and more potent in vitro antioxidant activity. In the Caco-2 monolayer cellular transport model, the transport efficiency of SePPs were significantly higher than those of selenite, and the binding of peptides enhanced the bioaccessibility and bioavailability of Se. The study elucidated the structure, composition, morphology bioaccessibility and bioavailabilityand of SePPs, providing support for SePPs functional food development.

Selenium Improves Yield and Quality in Prunella vulgaris by Regulating Antioxidant Defense, Photosynthesis, Growth, Secondary Metabolites, and Gene Expression Under Acid Stress

Prunella vulgaris, an essential component of traditional Chinese medicine, is suitable for growing in soil with a pH value ranging from 6.5 to 7.5. However, it is primarily cultivated in acidic soil regions of China, where its growth is frequently compromised by acidic stress. Selenium (Se) has been recognized for its potential to enhance stress tolerance in plants. However, its role in acid-stress-induced oxidative stress is not clear. In this study, the effects of varying Se concentrations on the growth and quality of P. vulgaris under acidic stress were investigated. The results showed that acid stress enhanced antioxidant enzyme activities, non-enzymatic antioxidant substances, and osmolyte content, accompanied by an increase in oxidant production and membrane damage. Furthermore, it decreased the photosynthetic capacity, inhibited root and shoot growth, and diminished the yield of P. vulgaris. In contrast, exogenous application of Se, particularly at 5 mg L-1, markedly ameliorated these adverse effects. Compared to acid-stressed plants, 5 mg L-1 Se treatment enhanced superoxide dismutase, peroxidase, ascorbate peroxidase, and glutathione peroxidase activities by 150.19%, 54.94%, 43.43%, and 45.55%, respectively. Additionally, soluble protein, soluble sugar, and proline contents increased by 11.75%, 23.32%, and 40.39%, respectively. Se application also improved root architecture and alleviated membrane damage by reducing hydrogen peroxide, superoxide anion, malondialdehyde, and electrolyte leakage levels. Furthermore, it significantly enhanced the photosynthetic capacity by elevating pigment levels, the performance of PSI and PSII, electron transfer, and the coordination of PSI and PSII. Consequently, plant growth and spica weight were significantly promoted, with a 12.50% increase in yield. Moreover, Se application upregulated key genes involved in flavonoid and phenolic acid metabolic pathways, leading to elevated levels of total flavonoids, caffeic acid, ferulic acid, rosmarinic acid, and hyperoside by 31.03%, 22.37%, 40.78%, 15.11%, and 20.84%, respectively, compared to acid-stressed plants. In conclusion, exogenous Se effectively alleviated the adverse effects of acid stress by improving the antioxidant system, growth, and photosynthetic capacity under acid stress, thus enhancing the yield and quality of P. vulgaris.

Digestive characteristics of Se-enriched proteins with different Se species and its effects on gut microbiota during in vitro APP/PS1 mice colonic fermentation

Cardamine violifolia, cabbage, and soybeans have a strong ability to accumulate selenium (Se), primarily in the forms of SeCys2, Se (VI), and SeMet, respectively. This study aims to investigate the digestive characteristics of Se-enriched proteins with different Se species, and its effects on gut microbiota during in vitro APP/PS1 mice colonic fermentation. The results showed that SeCys2 had the highest bioaccessibility (90.65 %) in Se-enriched C. violifolia protein (H-CVP), followed by SeMet at 84.53 %. In Se-enriched soybean protein (H-SBP), SeMet displayed the highest bioaccessibility at 82.98 %. Conversely, the bioaccessibility of Se (VI) in Se-enriched cabbage protein (H-CBP) was below 20 %, likely due to its conversion to Se (IV). Previous research indicated that, although the bioaccessibility of these Se species was relatively high, their bioavailability remained low. Unabsorbed Se may undergo fermentation in the colon. Consequently, we performed in vitro fermentation using feces from APP/PS1 mice to assess its effects on the gut microbiota of Alzheimer's disease (AD) mice. The results showed that H-CVP had a prebiotic effect on Bacteroidetes strain, while H-SBP significantly increased the abundance of Firmicutes and Lactobacillaceae in family level. H-CBP had weaker effects on gut microbiota health with the abundance of Enterobacteriaceae. Functional gene prediction of 16S rDNA sequencing data inferred that H-CVP may regulate intestinal health through the metabolism of cofactors and vitamins, while H-SBP could enhance carbohydrate metabolism. Overall, these findings emphasized the role of H-CVP and H-SBP in maintaining gut health in APP/PS1 mice, and demonstrated their potential to alleviate cognitive impairment.

The Synthesis of Selenium Nanoparticles and Their Applications in Enhancing Plant Stress Resistance: A Review

Nanoparticle-based strategies have emerged as transformative tools for addressing critical challenges in sustainable agriculture, offering precise modulation of plant-environment interactions through enhanced biocompatibility and stimuli-responsive delivery mechanisms. Among these innovations, selenium nanoparticles (SeNPs) present unique advantages due to their dual functionality as both essential micronutrient carriers and redox homeostasis modulators. Compared to conventional selenium treatments, SeNPs offer a more efficient and environmentally friendly solution for improving plant resilience while minimizing toxicity, even at low doses. This review provides a comprehensive analysis of methods for synthesizing SeNPs, including chemical reduction, green synthesis using plant extracts, and biological techniques with microbial agents. Additionally, the review discusses the effects of SeNPs on biotic and abiotic stress responses in plants, focusing on how these nanoparticles activate stress-response pathways and enhance plant immune function. The primary objective of this study is to offer theoretical insights into the application of SeNPs for addressing critical challenges in modern agriculture, such as improving crop yield and quality under stress conditions. Moreover, the research highlights the role of SeNPs in advancing sustainable agricultural practices by reducing reliance on chemical fertilizers and pesticides. The findings underscore the transformative potential of SeNPs in crop management, contributing to a more sustainable and eco-friendly agricultural future.

Pyro-Thermolysis Pattern Analysis of Selenopeptide in Selenium-Enriched Rice Based on Two-Dimensional Dietary Kinetics Evolution

Selenopeptides can be ideal dietary selenium (Se) supplements for humans. Currently, rice is not used much as a source of selenopeptides. Here, we executed the selenopeptidomics analysis of selenium-enriched rice protein hydrolysates using the full MS-dd-MS2 acquisition method and identified selenopeptides, including L{Se-Met}AK and other selenopeptides. Specifically, selenomethionine (SeMet) replaced methionine (Met) in the rice protein-Oryzain alpha chain (EC: 3.4.22) and generated a selenopeptide L{Se-Met}AK (molecular formula: C20H38N5O5Se) during subsequent protein hydrolysis. This selenopeptide was in 425-428 amino acid residues of the Oryzain alpha chain. Thermal processing led to selenopeptide cleavage, which affected the efficient retention of selenopeptides. Activation energy (Ea) was used to locate the quality control markers in the thermal degradation of selenopeptides. Therefore, this study established the thermal degradation rate equation for the selenopeptide L{Se-Met}AK at 100 °C, 110 and 120 °C; and identified the pyrolysis products, including L{Se-Met}A, LMA, LMAK, K1, and K2, involving C-N cleavage on the amide bond of alanine and lysine, C-Se bond cleavage and C-N cleavage on the amide bond of alanine and Met; the fit coefficients of the thermal reaction models were ≥0.9248, which could accurately quantify the real-time pyrolysis kinetic process; and LMAK had a lower Ea of 88.20 kJ/mol, which made it easier to produce. In summary, LMAK can be used as a quality control marker in the pyrolysis process, providing technical support for the efficient retention of selenopeptides.

Selenium and Selenoproteins: Mechanisms, Health Functions, and Emerging Applications

Selenium (Se) is an essential trace element crucial for human health that primarily functions as an immunonutrient. It is incorporated into polypeptides such as selenocysteine (SeC) and selenomethionine (SeMet), two key amino acids involved in various biochemical processes. All living organisms can convert inorganic Se into biologically active organic forms, with SeMet being the predominant form and a precursor for SeC production in humans and animals. The human genome encodes 25 selenoprotein genes, which incorporate low-molecular-weight Se compounds in the form of SeC. Organic Se, especially in the form of selenoproteins, is more efficiently absorbed than inorganic Se, driving the demand for selenoprotein-based health products, such as functional foods. Se-enriched functional foods offer a practical means of delivering bioavailable Se and are associated with enhanced antioxidant properties and various health benefits. Recent advancements in selenoprotein synthesis have improved our understanding of their roles in antioxidant defense, cancer prevention, immune regulation, anti-inflammation, hypoglycemia, cardiovascular health, Alzheimer's disease, fertility, and COVID-19. This review highlights key selenoproteins and their biological functions, biosynthetic pathways, and emerging applications while highlighting the need for further research.

Clinical and mechanistic insights into biomedical application of Se-enriched probiotics and biogenic selenium nanoparticles

Selenium is an essential element with various industrial and medical applications, hence the current considerable attention towards the genesis and utilization of SeNPs. SeNPs and other nanoparticles could be achieved via physical and chemical methods, but these methods would not only require expensive equipment and specific reagents but are also not always environment friendly. Biogenesis of SeNPs could therefore be considered as a less troublesome alternative, which opens an excellent window to the selenium and nanoparticles' world. bSeNPs have proved to exert higher bioavailability, lower toxicity, and broader utility as compared to their non-bio counterparts. Many researchers have reported promising features of bSeNP such as anti-oxidant and anti-inflammatory, in vitro and in vivo. Considering this, bSeNPs have been tried as effective agents for health disorders, especially as constituents of probiotics. This article briefly reviews selenium, selenium nanoparticles, Se-enriched probiotics, and bSeNPs' usage in an array of health disorders. Obviously, there are very many articles on bSeNPs, but we wanted to summarize studies on prominent bSeNPs features published in the twenty-first century. This review is hoped to give an outlook to researchers for their future investigations, ultimately serving better care of health disorders.

Amine-Promoted Three-Component Radical Selenofunctionalization for the Construction of β-Hydroxy Selenide Derivatives

An amine-promoted three-component radical selenofunctionalization reaction of alkenes with TBHP and diselenide is disclosed. The reaction conditions are mild and suitable for a wide range of substrates (29 examples), and all give the corresponding hydroxyselenenylation products in moderate to excellent yields. In addition, preliminary studies on the mechanism reveal that the current method might proceed via a radical pathway. TBHP serves as both radical initiator and the source of hydroxyl group.

Improvement of cereal- and legume-derived protein quality with selenium and sulfur for plant food production

Selenium (Se) is essential for human and animal health and nutritional status. As humans cannot produce Se, it must be obtained from the diet. Adequate Se supplementation improves innate immunity, increases antioxidant capacity and helps prevent various disorders. Sulfur (S) is an indispensable nutrient that affects plant growth, performance and yield. Cereals and legumes are global staple foods, and their proteins are considered sustainable plant-based meat alternatives, which are increasingly popular. Owing to their physicochemical similarities, the crosstalk between Se and S influences cereal and grain-legume derived proteins. Modifications induced by Se and S might improve the protein quality of harvested cereal and legume grains. This timely review not only identifies the knowledge gaps in this research area focusing on Se and S enrichment in cereals and legumes but also emphasizes the potential of this unexplored area for new applications. S enrichment resulted in better quality properties in the bread of wheat flour and stimulated the expression of S-rich globulins and albumins in legumes. Se supplementation enhanced the emulsifying capacity of legumes (e.g. chickpeas). The improvement of protein fractions in cereal and legume grains has the potential to revolutionize protein processing to offer new alternatives to produce an array of S- and Se-enriched cereal and legume products. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effects of selenium biofortification on Pleurotus eryngii protein structure and digestive properties and its mitigation of lead toxicity: An in vitro and in vivo study

The development of safe and efficient dietary selenium sources to promote lead excretion is of great importance for public health. In this research, proteins from original Pleurotus eryngii (PEP) and Se-enriched P. eryngii (SePEP, Se content: 360.64 ± 3.11 mg/kg) were extracted and purified respectively for the further comparison of structural and digestive characteristics. Caco-2 monolayer membrane, in vitro simulated fermentation and acute lead exposure mice model were constructed to evaluate the effects of PEP and SePEP on lead excretion. The results indicated that Se biofortification significantly altered the amino acid composition and reduced the total sulfhydryl content of proteins (p < 0.05). SePEP could better alleviate lead-induced intestinal barrier damage and inhibit the absorption and accumulation of lead in both cell and mice models. Furthermore, SePEP promoted fecal adsorption and excretion of lead via regulating gut microbiota composition. SePEP can be considered a potentially functional Se source to promote lead excretion.

Analysis of Microheterogeneous Glutelin Subunits and Highly Efficient Identification of Selenylation Peptides by In-Gel Proteolysis: Focus on Se-Enriched Rice

Selenylation of cysteine and methionine thiols through selenate supplements increases the content of selenium-containing amino acids in various agricultural products. This modification results in numerous biological and health benefits. Despite their critical roles in human physiology, methods for high-coverage and efficient identification of selenylation peptides are limited. This study systematically developed a mass spectrometric method to identify selenylation peptides combined with in-gel trypsin proteolysis. In-gel proteolysis identified the two well-separated bands containing rice glutelin. We identified 11 rice glutelin subunits along with 42 selenylation peptides from the glutelin acidic subunits and 30 selenylation peptides from the glutelin basic subunits with high confidence. A comprehensive evaluation disclosed the mapping of selenium-containing rice glutelin subunits. Additionally, the selenylation modification of peptides coexisted with oxidation and iodoacetamide (IAM) alkylation. Moreover, the multidimensional MS criteria validated the results, while spectral statistics revealed the veritable Se/S substitution degree in Se-enriched rice. These findings collectively demonstrated the presence of numerous selenation sites in microheterogeneous glutelin subunits, thereby enhancing our understanding of the seleno-peptidomics of rice proteins. As significant bioactive organic compounds, the identified peptides in this study are promising candidates for a variety of bioactivities, including neuroprotective, anti-inflammatory, antioxidant, hepatoprotective, and immunomodulatory effects.

Seed and foliar application of nano-selenium improves sesame triacylglycerols and oil yield via photosynthetic pigment and enzymatic and chemical antioxidant enhancement revealed by spectrophotometric, UHPLC-analysis and chemometric modeling

The current study aimed to investigate the effects of plant-mediated selenium nanoparticles (SeNPs) on plant growth, photosynthetic pigments, antioxidant activity, and the triacylglycerol profile of sesame (Sesamum indicum L.). The green synthesis of SeNPs was achieved using garlic extract, resulting in spherical nanoparticles with an average size range of 70-75 nm. Three SeNP treatments (T3, 30 ppm; T4, 40 ppm; and T5, 50 ppm) were applied through seed and foliar spray on six sesame varieties (V1, TS-5; V2, TH-6; V3, Til-18; V4, Niab Millennium; V5, Niab Pearl; and V6, NS-16). All enzymatic antioxidant parameters showed an increase in the treated groups, such as SOD (74.4% in V1 at T4), POD (43% in V5 at T5), APX (62% in V1 at T3), and GPX (31.56% in V3 at T4). CAT showed the highest percentage improvement in T5 for V1, V2, V4, and V5, while V3 and V4 exhibited the highest values at T4. Likewise, seed antioxidant parameters also showed increase in antioxidant activity, highest total phenolic content (6.06 mg GAE/g) was found at T5 treatment with percent increase of 27.41%, but the highest percent increase was found to be at T4 treatments in V1 with increase of 46.83%. Percent oil yield was also noted to be higher as highest percent (60%) oil yield was obtained at T4 treatment in V3. Ultra High Performance Mass-Spectrometry (UHPLC-MS) analysis and chemometric modeling suggested a total of 10 triacylglycerol (TG) biomarkers separating untreated groups, with higher relative abundance values at T4 and T5 treatments compared to control. PCA and correlation analysis showed clustering of untreated groups from T4 and T5, which suggests that these two treatments result in higher accumulation of oil. A generalized linear model with ANOVA showed a highly significant impact of treatments on all the growth and oil parameters, with significance involvement of varieties. The interaction between variety and treatment showed no significant effect on the growth and oil biomarkers of sesame. However, it can be concluded that the T4 and T5 treatments (40 ppm and 50 ppm) of SeNPs, applied through seed and foliar methods, have a strong influence on the overall growth and oil yield of sesame. This warrants further transcriptomic and molecular analysis to gain deeper insight into the mechanisms of action of SeNPs.

The composition, extraction, functional property, quality, and health benefits of coconut protein: A review

Coconut is widely appreciated for its distinctive flavor and is commonly utilized in the production of a variety of goods. Coconut protein, a by-product derived from coconut oil and coconut milk cake, is frequently underutilized or discarded. This study provides a comprehensive overview of the distribution and composition of coconut protein. Analyses reveal that coconut protein, specifically 11S globulin and 7S globulin, is predominantly found in coconut flesh. Furthermore, various extraction techniques for coconut protein, such as chemical, enzymatic, and physical methods, are discussed. The alkali dissolution and acid precipitation methods are widely utilized for extracting coconut protein, with the potential for enhancement through the incorporation of physical methods such as ultrasound. The evaluation of functional properties, quality, and health benefits of coconut protein is essential, given the limitations imposed by its solubility. Modification may be necessary to optimize its functional properties. Coconut presents a promising source of food protein, characterized by balanced amino acid composition, high digestibility, and low allergenic potential. In conclusion, this study provides a comprehensive overview of the extraction methods, functional properties, quality, and nutritional benefits of coconut protein, offering insights for potential future research directions in the field. Additionally, the information presented may serve as a valuable reference for incorporating coconut protein into plant-based food products.

Characterization, in vitro antioxidant activity and stability of cattle bone collagen peptides‑selenium chelate

In this study, cattle bone collagen peptides-selenium chelate (CCP-Se) was prepared and its structure, oxidation resistance and stability were characterized. The selenium binding capacity was 33.65 ± 0.13 mg/g by optimized preparation conditions. Structural analysis showed that selenium ions bound mainly to the amino nitrogen, carboxyl oxygen and hydroxyl oxygen atoms of the cattle bone collagen peptide (CCP). The microstructure and particle size analyses showed that the particle size of CCP-Se was increased and formed a regular and compact crystal structure compared with CCP. Additionally, CCP-Se exhibited excellent antioxidant activity. Stability analysis showed that CCP-Se was stable in thermal processing, simulated in vitro digestion and acid/alkali tolerance tests. The intestinal selenium permeability of CCP-Se was significantly better than sodium selenite (p < 0.05). This study provides reference for the high-value application of cattle bone and suggests the potential of CCP-Se as a new effective selenium supplement.

Preparation and antitumor activity of selenium nanocomposite stabilized by AAGL from Agerocybe aegerita

Selenium nanoparticles (SeNPs) have limited bioavailability because of their poor stability in aqueous solutions. AAGL, a naturally active protein, extracted from Agrocybe aegerita has strong antitumor activity. However, whether AAGL can been used to stabilize SeNPs, and exerts anti-lung cancer effects remains unknown. In this study, a novel nanocomposite, AAGL-SeNPs, was prepared using AAGL-encapsulated SeNPs. The particle size of the AAGL-SeNPs was approximately 206.1 nm, which was uniform and well dispersed in aqueous solution and showed satisfactory stability. AAGL-SeNPs was non-toxic and reduced the hepatotoxicity of AAGL in mice. Importantly, AAGL-SeNPs inhibited the proliferation of lung cancer cells and suppressed tumor growth in tumor-bearing mice. AAGL-SeNPs enhanced the cytotoxic effects on lung cancer cells by stimulating immune cells. In addition, the combination of AAGL-SeNPs and osimertinib inhibited lung cancer, and AAGL-SeNPs reversed osimertinib resistance in H1975 cells. Mechanistically, Krüppel-like transcriptional factor 4 (KLF4) was identified by data-independent acquisition mass spectrometry (DIA-MS), and its expression levels in lung cancer increased after AAGL-SeNPs treatment. This study demonstrated that nanocomposite AAGL-SeNPs is stable, safe, and has excellent antitumor efficacy, which will be a potential therapeutic drug for lung cancer treatment.

Highly selective localized surface plasmon resonance sensor for selenium diagnosis in selenium-rich soybeans

It is a challenge to determine selenium in acid aqueous for environmental monitoring and selenium-rich agricultural diagnosis. Herein, we developed a novel localized surface plasmon resonance (LSPR) sensor to detect Se(IV) ions based on the extraordinary laterals etching of gold nanorods (AuNRs). The etching started from the laterals in the low amount of Se(IV) ions, and accompanied by an apparent red shift of the longitudinal plasmon band (LPB), and then transformed to the tips etching with the upward of Se(IV) ions, the LPB band immediately shifted to the shorter wavelength. The red shift change (Δλ) of LPB band was utilized to quantitative analysis instead of blue shift or absorbance intensity, which gave a high selectivity for the proposed sensor. More importantly, this sensor could be performed in 0.1 mol/L of HCl solution, which achieved the seamlessly jointing with the pretreatment of complex samples, without time-consuming pH adjustment.Successful selenium detection was demonstrated in complex soybean samples that collected from the maturity after spraying organic chelated selenium at full flower period. The sensor provided a promising way to monitor and diagnose selenium in complex environmental samples and selenium-rich crops.

Protective role of seleno-amino acid against IBD via ferroptosis inhibition in enteral nutrition therapy

The interplay between intestinal barrier degradation and trace element insufficiency worsens inflammatory bowel disease (IBD). Selenium (se) is essential for glutathione peroxidase 4 (GPX4) synthesis, which protects against intestinal epithelial cell injury in IBD. However, malnutrition and malabsorption limit the availability of dietary selenium. This study investigated the protective effects of naturally occurring seleno-amino acids on the intestinal barrier in an IBD animal model by promoting GPX4 synthesis. L-se-methylselenocystine (seMc) supplementation reversed decreased GPX4 expression levels, alleviated glutathione depletion and scavenged reactive oxygen species in vitro. In vivo, enteral nutrition combined with seMc protected the intestinal barrier and alleviated IBD-related symptoms by inhibiting ferroptosis and reversing lipid peroxidation in epithelial cells while reducing immune cell infiltration. Our findings suggest that seleno-amino acid-based nutritional formulations may provide a basis for nutritional support to alleviate complex cycles between intestinal barrier damage and malnutrition in IBD patients.

Genetic Biofortification of Winter Wheat with Selenium (Se)

Wheat is one of the three most important cereals in the world, along with rice and maize. It serves as the primary food and source of energy for about 30-40% of the world's population. However, the low levels of micronutrients in wheat grains can lead to deficiencies of those micronutrients in people whose dietary habits are mostly based on cereals such as wheat. Apart from iron (Fe) and zinc (Zn), a lack of selenium (Se) is also one of the biggest problems in the world. The essentiality of Se has been confirmed for all animals and humans, and the lack of this micronutrient can cause serious health issues. Wheat dominates the world's cereal production, so it is one of the best plants for biofortification. Due to the fact that agronomic biofortification is not an economical or environmentally acceptable approach, genetic improvement of cereals such as wheat for the enhanced content of micronutrients in the grain represents the most efficient biofortification approach.

Se-Pair Search for Deciphering Selenium-Encoded Peptide and a Pyrolysis-Thermolysis Dietary Model for Minimizing Loss of "KKSe(M)R" during Processing

Dietary deficiency of selenium is a global health hazard. Supplementation of organic selenopeptides via food crops is a relatively safe approach. Selenopeptides with heterogeneous selenium-encoded isotopes or a poorly fragmented peptide backbone remain unidentified in site-specific selenoproteomic analysis. Herein, we developed the Se-Pair Search, a UniProtKB-FASTA-independent peptide-matching strategy, exploiting the fragmentation patterns of shared peptide backbones in selenopeptides to optimize spectral interpretation, along with developing new selenosite assignment schemes (steps 1-3) to standardize selenium-localization data reporting for the selenoproteome community and thereby facilitating the discovery of unexpected selenopeptides. Using selenium-biofortified rice under cooking, fermentation, and high-temperature and high-pressure processing conditions as a pyrolysis-thermolysis dietary model, we probed the single-molecule-level kinetic evolution of the novel selenopeptide "KKSe(M)R" with qual-quantitative information on graph-theory-oriented localization calculations, abundance patterns, activation energy, and rate constants at a selenoproteome-wide scale. We ground-truth-annotated thirteen pyrolysis-thermolysis products and inferred four pyrolysis-thermolysis pathways to characterize the formation reactivity of the main intermediate variables of KKSe(M)R and constructed an advanced probe-type ultrasound technique prior to pyrolysis-thermolysis conditions for minimizing loss of KKSe(M)R during processing. Importantly, we reveal the unappreciated pyro-excitation diversion of KKSe(M)R at pyrolysis-thermolysis time and temperature matrices. These findings provide pioneering theoretical guidance for controlling dietary selenium supplementation within the safety thresholds.

Combined transcriptome and metabolome analyses reveal the effects of selenium on the growth and quality of Lilium lancifolium

Lilium lancifolium Thunb (L. lancifolium) is an important medicinal and edible plant with outstanding functionality for selenium (Se) biofortification. However, the molecular response of L. lancifolium to exogenous Se has not been fully elucidated. In this study, the effects of different levels of Se on L. lancifolium growth and quality were explored by transcriptome, metabolome and biochemical analyses. The results showed that the total Se and organic Se content in L. lancifolium bulbs increased with increasing Se dosage (0-8.0 mmol/L). Moreover, Se stimulated the growth of L. lancifolium at low level (2.0 mmol/L) but showed an inhibitory effect at high levels (≥4.0 mmol/L). Metabolomic and biochemical analyses revealed that the bulb weight and the content of amino acid, soluble sugar, and soluble protein were significantly increased in the 2.0 mmol/L Se treatment compared with those in the control (0 mmol/L Se). Transcriptome and metabolome analyses revealed that the significant upregulation of the GPD1, GPAT and ADPRM genes promoted glycerophospholipid accumulation. Additionally, the significantly upregulated glyA and downregulated asnB, nadB, thrA and SAT genes coordinate to the regulation of amino acid biosynthesis. The significantly upregulated SUS, bgl B, BAM, and SGA1 genes were involved in soluble sugar accumulation under Se treatment. In summary, this study identified the optimal Se concentration (2.0 mmol/L), which significantly improved the growth and nutritional quality of L. lancifolium and contributed to understanding the combined effects of Se treatment on the expression of genes and the accumulation of metabolites in L. lancifolium bulbs.

Foliar selenium biofortification of soybean: the potential for transformation of mineral selenium into organic forms

Introduction

Selenium (Se) deficiency, stemming from malnutrition in humans and animals, has the potential to disrupt many vital physiological processes, particularly those reliant on specific selenoproteins. Agronomic biofortification of crops through the application of Se-containing sprays provides an efficient method to enhance the Se content in the harvested biomass. An optimal candidate for systematic enrichment, guaranteeing a broad trophic impact, must meet several criteria: (i) efficient accumulation of Se without compromising crop yield, (ii) effective conversion of mineral Se fertilizer into usable organically bound Se forms (Seorg), (iii) acceptance of a Se-enriched crop as livestock feed, and (iv), interest from the food processing industry in utilization of Se-enriched outputs. Hence, priority should be given to high-protein leafy crops, such as soybean.

Methods

A three-year study in the Czech Republic was conducted to investigate the response of field-grown soybean plants to foliar application of Na2SeO4 solutions (0, 15, 40, and 100 g/ha Se); measured outcomes included crop yield, Se distribution in aboveground biomass, and the chemical speciation of Se in seeds.

Results and Discussion

Seed yield was unaffected by applied SeO4 2-, with Se content reaching levels as high as 16.2 mg/kg. The relationship between SeO4 2-dose and Se content in seeds followed a linear regression model. Notably, the soybeans demonstrated an impressive 73% average recovery of Se in seeds. Selenomethionine was identified as the predominant species of Se in enzymatic hydrolysates of soybean, constituting up to 95% of Seorg in seeds. Minor Se species, such as selenocystine, selenite, and selenate, were also detected. The timing of Se spraying influenced both plant SeO4 2- biotransformation and total content in seeds, emphasizing the critical importance of optimizing the biofortification protocol. Future research should explore the economic viability, long-term ecological sustainability, and the broad nutritional implications of incorporating Se-enriched soybeans into food for humans and animals.

Selenium in plants: A nexus of growth, antioxidants, and phytohormones

Selenium (Se) is an essential micronutrient for both human and animals. Plants serve as the primary source of Se in the food chain. Se concentration and availability in plants is influenced by soil properties and environmental conditions. Optimal Se levels promote plant growth and enhance stress tolerance, while excessive Se concentration can result in toxicity. Se enhances plants ROS scavenging ability by promoting antioxidant compound synthesis. The ability of Se to maintain redox balance depends upon ROS compounds, stress conditions and Se application rate. Furthermore, Se-dependent antioxidant compound synthesis is critically reliant on plant macro and micro nutritional status. As these nutrients are fundamental for different co-factors and amino acid synthesis. Additionally, phytohormones also interact with Se to promote plant growth. Hence, utilization of phytohormones and modified crop nutrition can improve Se-dependent crop growth and plant stress tolerance. This review aims to explore the assimilation of Se into plant proteins, its intricate effect on plant redox status, and the specific interactions between Se and phytohormones. Furthermore, we highlight the proposed physiological and genetic mechanisms underlying Se-mediated phytohormone-dependent plant growth modulation and identified research opportunities that could contribute to sustainable agricultural production in the future.

Selenite foliar application increased the accumulation of medicinal components in Paeonia ostii by promoting antioxidant capacity, reducing oxidative stress, and improving photosynthetic capacity

The effects of selenite (0, 15, 30, 45 mg L-1) on physiological characteristics and medicinal components of Paeonia ostii were analyzed. The results showed that selenite application promoted the activity of superoxide dismutase and the contents of soluble sugar, proline, carotenoids, total flavonoids, and total polyphenols, and decreased the contents of reactive oxygen species, relative electrical conductivity, and malondialdehyde. In addition, selenite also increased chlorophyll content, improved electron transfer ability, PSI and PSII performance, and the coordination between PSI and PSII, which significantly improved photosynthetic capacity. Moreover, selenite treatment also greatly increased the contents of gallic acid, catechin, albiflorin, paeoniflorin, benzoic acid, and paeonol in Moutan cortex radicis (MCR). These results showed that selenite effectively protected the photosynthetic apparatus from photooxidative damage by enhancing antioxidant capacity, improving photosynthetic capacity, and increasing the content of the medicinal compounds in MCR.

Egg Yolk Selenopeptides: Preparation, Characterization, and Immunomodulatory Activity

In this study, egg yolk selenium peptides (Se-EYP) were prepared using double-enzyme hydrolysis combined with a shearing pretreatment. The properties of the selenopeptides formed were then characterized, including their yield, composition, molecular weight distribution, antioxidant activity, in vitro digestion, and immunomodulatory activity. The peptide yield obtained after enzymatic hydrolysis using a combination of alkaline protease and neutral protease was 74.5%, of which 82.6% had a molecular weight <1000 Da. The selenium content of the lyophilized solid product was 4.01 μg/g. Chromatography-mass spectrometry analysis showed that 88.6% of selenium in Se-EYP was in the organic form, of which SeMet accounted for 60.3%, SeCys2 for 21.8%, and MeSeCys for 17.9%. After being exposed to in vitro simulated digestion, Se-EYP still had 65.1% of oligopeptides present, and the in vitro antioxidant activity was enhanced. Moreover, Se-EYP exhibited superior immune detection indices, including immune organ index, level of immune factors in the serum, histopathological changes in the spleen, and selenium content in the liver. Our results suggest that Se-EYP may be used as selenium-enriched ingredients in functional food products.

In vitro digestion and fecal fermentation of selenocompounds: impact on gut microbiota, antioxidant activity, and short-chain fatty acids

Selenium bioavailability is critically influenced by gut microbiota, yet the interaction dynamics with selenocompounds remain unexplored. Our study found that L-Selenomethionine (SeMet) and Se-(Methyl)seleno-L-cysteine (MeSeCys) maintained stability during in vitro gastrointestinal digestion. In contrast, Selenite and L-Selenocystine (SeCys2) were degraded by approximately 13% and 35%. Intriguingly, gut microflora transformed MeSeCys, SeCys2, and Selenite into SeMet. Moreover, when SeCys2 and Selenite incubated with gut microbiota, they produced red selenium nanoparticles with diameters ranging between 100 and 400 nm and boosted glutathione peroxidase activity. These changes were positively associated with an increased relative abundance of unclassified_g__Blautia (Family Lachnospiraceae), Erysipelotrichaceae_UCG-003 (Family Erysipelatoclostridiaceae), and uncultured_bacterium_g__Subdoligranulum (Family Ruminococcaceae). Our findings implied that differential microbial sensitivities to selenocompounds, potentially attributable to their distinct mechanisms governing selenium uptake, storage, utilization, and excretion.

Selenium Decipher: Trapping of Native Selenomethionine-Containing Peptides in Selenium-Enriched Milk and Unveiling the Deterioration after Ultrahigh-Temperature Treatment

Selenopeptide identification relies on databases to interpret the selenopeptide spectra. A common database search strategy is to set selenium as a variable modification instead of sulfur on peptides. However, this approach generally detects only a fraction of selenopeptides. An alternative approach, termed Selenium Decipher, is proposed in the present study. It involves identifying collision-induced dissociation-cleavable selenomethionine-containing peptides by iteratively matching the masses of seleno-amino acids in selenopeptide spectra. This approach uses variable-data-independent acquisition (vDIA) for peptide detection, providing a flexible and customizable window for secondary mass spectral fragmentation. The attention mechanism was used to capture global information on peptides and determine selenomethionine-containing peptide backbones. The core structure of selenium on selenomethionine-containing peptides generates a series of fragment ions, namely, C3H7Se+, C4H10NSe+, C5H7OSe+, C5H8NOSe+, and C7H11N2O2Se+, with known mass gaps during higher-energy collisional dissociation (HCD) fragmentation. De-selenium spectra are generated by removing selenium originating from selenium replacement and then reassigning the precursors to peptides. Selenium-enriched milk is obtained by feeding selenium-rich forage fed to cattle, which leads to the formation of native selenium through biotransformation. A novel antihypertensive selenopeptide Thr-Asp-Asp-Ile-SeMet-Cys-Val-Lys TDDI(Se)MCVK was identified from selenium-enriched milk. The selenopeptide (IC50 = 60.71 μM) is bound to four active residues of the angiotensin-converting enzyme (ACE) active pocket (Ala354, Tyr523, His353, and His513) and two active residues of zinc ligand (His387 and Glu411) and exerted a competitive inhibitory effect on the spatial blocking of active sites. The integration of vDIA and the iteratively matched seleno-amino acids was applied for Selenium Decipher, which provides high validity for selenomethionine-containing peptide identification.

Highly Electrophilic Intermediates in the Bypass Mechanism of Glutathione Peroxidase: Synthesis, Reactivity, and Structures of Selenocysteine-Derived Cyclic Selenenyl Amides

Selenocysteine (Sec)-derived cyclic selenenyl amides, formed by the intramolecular cyclization of Sec selenenic acids (Sec-SeOHs), have been postulated to function as protective forms in the bypass mechanism of glutathione peroxidase (GPx). However, their chemical properties have not been experimentally elucidated in proteins or small-molecule systems. Recently, we reported the first nuclear magnetic resonance observation of Sec-SeOHs and their cyclization to the corresponding cyclic selenenyl amides by using selenopeptide model systems incorporated in a molecular cradle. Herein, we elucidate the structures and reactivities of Sec-derived cyclic selenenyl amides. The crystal structures and reactions toward a cysteine thiol or a 1,3-diketone-type chemical probe indicated the highly electrophilic character of cyclic selenenyl amides. This suggests that they can serve not only as protective forms to suppress the inactivation of Sec-SeOHs in GPx but also as highly electrophilic intermediates in the reactions of selenoproteins.

Demonstration of the Formation of a Selenocysteine Selenenic Acid through Hydrolysis of a Selenocysteine Selenenyl Iodide Utilizing a Protective Molecular Cradle

Selenocysteine selenenic acids (Sec-SeOHs) and selenocysteine selenenyl iodides (Sec-SeIs) have long been recognized as crucial intermediates in the catalytic cycle of glutathione peroxidase (GPx) and iodothyronine deiodinase (Dio), respectively. However, the observation of these reactive species remained elusive until our recent study, where we successfully stabilized Sec-SeOHs and Sec-SeIs using a protective molecular cradle. Here, we report the first demonstration of the chemical transformation from a Sec-SeI to a Sec-SeOH through alkaline hydrolysis. A stable Sec-SeI derived from a selenocysteine methyl ester was synthesized using the protective cradle, and its structure was determined by crystallographic analysis. The alkaline hydrolysis of the Sec-SeI at -50 °C yielded the corresponding Sec-SeOH in an 89% NMR yield, the formation of which was further confirmed by its reaction with dimedone. The facile and nearly quantitative conversion of the Sec-SeI to the Sec-SeOH not only validates the potential involvement of this process in the catalytic mechanism of Dio, but also highlights its utility as a method for producing a Sec-SeOH.

Transcriptome analysis reveals the molecular mechanism of different forms of selenium in reducing cadmium uptake and accumulation in wheat seedlings

Selenium (Se) can counteract cadmium (Cd) toxicity in wheat, but the molecular mechanism of different Se forms reducing Cd uptake and accumulation in wheat seedlings remain unclear. Here, a hydroponic experiment was conducted to investigate the effects of three Se forms (selenite (Se(IV)), selenate (Se(VI)) and seleno-L-methionine (SeMet)) on Cd2+ influx, Cd subcellular distribution, and Cd accumulation in wheat seedlings, and the underlying molecular mechanisms were investigated through transcriptome analysis. Consequently, Se(IV) and Se(VI) addition significantly reduced root Cd concentration by 74.3% and 80.8%, respectively, and all Se treatments significantly decreased shoot Cd concentration by approximately 34.2%-74.9%, with Se(IV) addition having the most pronounced reducing effect. Transcriptome analysis showed the reduction of Cd accumulation after Se(IV) addition was mainly due to the downregulation of Cd uptake genes. The inhibition of Cd accumulation after Se(VI) addition was not only associated with the downregulation of Cd uptake genes, but also related to the sequestration of Cd in vacuole. For SeMet addition, the reduction of Cd accumulation was mainly related to the sequestration of Cd in vacuole as GSH-Cd. The above findings provide novel insights to understand the effects of different forms of Se on Cd uptake and accumulation and tolerance in wheat.

Incorporation of Selenium Derived from Nanoparticles into Plant Proteins in Vivo

Diets comprising selenium-deficient crops have been linked to immune disorders and cardiomyopathy. Selenium nanoparticles (SeNPs) have emerged as a promising nanoplatform for selenium-biofortified agriculture. However, SeNPs fail to reach field-scale applications due to a poor understanding of the fundamental principles of its behavior. Here, we describe the transport, transformation, and bioavailability of SeNPs through a combination of in vivo and in vitro experiments. We show synthesized amorphous SeNPs, when sprayed onto the leaves of Arabidopsis thaliana, are rapidly biotransformed into selenium(IV), nonspecifically incorporated as selenomethionine (SeMet), and specifically incorporated into two selenium-binding proteins (SBPs). The SBPs identified were linked to stress and reactive oxygen species (mainly H2O2 and O2-) reduction, processes that enhance plant growth and primary root elongation. Selenium is transported both upwards and downwards in the plant when SeNPs are sprayed onto the leaves. With the application of Silwet L-77 (a common agrochemical surfactant), selenium distributed throughout the whole plant including the roots, where pristine SeNPs cannot reach. Our results demonstrate that foliar application of SeNPs promotes plant growth without causing nanomaterial accumulation, offering an efficient way to obtain selenium-fortified agriculture.

Comparison of Neuroprotection and Regulating Properties on Gut Microbiota between Selenopeptide Val-Pro-Arg-Lys-Leu-SeMet and Its Native Peptide Val-Pro-Arg-Lys-Leu-Met In Vitro and In Vivo

Selenopeptides are promising candidates for intervening in neuroinflammation; however, the key role of selenium (Se) in selenopeptides remains poorly understood. To address this gap, we compared the neuroprotective effects of selenopeptide Val-Pro-Arg-Lys-Leu-SeMet (namely, Se-P1) and its native peptide Val-Pro-Arg-Lys-Leu-Met (namely, P1). Our results demonstrate that Se-P1 treatment exhibits superior antioxidant and antineuroinflammatory effects in PC12 cells and lipopolysaccharide (LPS)-injured mice compared to P1. Moreover, the administration of Se-P1 and P1 resulted in a shift in the gut microbiota composition. Notably, during LPS-induced injury, Se-P1 treatment demonstrated greater stability in maintaining gut microbiota composition compared to P1 treatment. Specifically, Se-P1 may have a positive impact on gut microbiota dysbiosis by modulating inflammatory-related bacteria such as enhancing Lactobacillus abundance while reducing that of Lachnospiraceae_NK4A136_group. Furthermore, the alteration of metabolites induced by Se-P1 treatment exhibited a significant correlation with gut microbiota, subsequently modulating the inflammatory-related metabolic pathways including histidine metabolism, lysine degradation, and purine metabolism. These findings suggest that organic Se contributes to the bioactivities of Se-P1 in mitigating neuroinflammation in LPS-injured mice compared to P1. These findings hold significant value for the development of potential preventive or therapeutic strategies against neurodegenerative diseases and introduce novel concepts in selenopeptide nutrition and supplementation recommendations.

Identification and preparation of selenium-containing peptides from selenium-enriched Pleurotus eryngii and their protective effect on lead-induced oxidative damage in NCTC1469 hepatocytes

BACKGROUND

Lead (Pb) is a highly toxic and persistent substance that easily accumulates in living organisms, eliciting cellular toxicity and oxidative stress. Some selenium-containing proteins and peptides prepared from plant extracts are beneficial for protecting the body's health and resisting external disturbances. In the present study, selenium-containing peptide species were prepared from selenium-enriched Pleurotus eryngii protein hydrolysates and to evaluate the benefits of selenium-containing peptides on Pb-induced oxidative stress in NCTC1469 hepatocytes.

RESULTS

Trypsin was selected as primary enzyme to hydrolyze the selenium-enriched protein (SPH). The optimal hydrolysis conditions were: hydrolysis time, 1.5 h; initial pH 8.0. The SPH was digested by trypsin and then purified by ultrafiltration, gel filtration chromatography and reversed-phase HPLC to obtain the selenium-containing peptides SPH-I-2. Furthermore, SPH-I-2 was analyzed and a number of total 12 selenium-containing peptides were identified by liquid chromatography-tandem mass spectroscopy. The NCTC1469 cell culture study showed that selenium-containing peptides were capable of reducing reactive oxygen species levels and regulating the Keap1/Nrf2 pathway by upregulating Nrf2, HO-1, GCLC, GCLM and NQO1 genes and downregulating Keap1 genes. Moreover, selenium-containing peptides were also able to suppress Pb-induced elevated levels of nitric oxide (NO), lactate dehydrogenase (LDH), malondialdehyde (MDA), increase antioxidant enzyme activity and alleviate cell apoptosis.

CONCLUSION

The present study indicated that the selenium-containing peptides could protect cells from Pb²⁺ -induced oxidative stress. © 2023 Society of Chemical Industry.

Selenomethionine promotes ANXA2 phosphorylation for proliferation and protein synthesis of myoblasts and skeletal muscle growth

Selenomethionine (Se-Met) has many beneficial effects on higher animals and human, and can regulate cellular physiology through distinct signaling pathways. However, the role and molecular mechanism of Se-Met in skeletal muscle growth remains unclear. In this study, we observed the effects of Se-Met on C2C12 myoblasts and skeletal muscle growth of mice, and explored the corresponding molecular mechanism. Se-Met affected proliferation and protein synthesis of C2C12 myoblasts in a hormesis type of relationship, and had an optimal stimulatory effect at 50 µM concentration. Se-Met also affected mTOR, ANXA2, and PKCα phosphorylation in the same manner. ANXA2 knockdown blocked the stimulation of Se-Met on cell proliferation and protein synthesis and inhibition of Se-Met on autophagy of C2C12 myoblasts. Western blotting analysis showed that PI3K inhibition blocked the stimulation of Se-Met on mTOR phosphorylation. ANXA2 knockdown further blocked the stimulation of Se-Met on PI3K and mTOR phosphorylation. Point mutation experiment showed that ANXA2 mediated the stimulation of Se-Met on the PI3K-mTOR signaling through phosphorylation at Ser26. PKCα interacted with ANXA2, and PKCα knockdown blocked the stimulation of Se-Met on ANXA2 phosphorylation at Ser26. Se-Met addition (7.5mg/kg diet, 4 weeks) increased mouse carcass weight, promoted gastrocnemius skeletal muscle growth and ANXA2 and mTOR phosphorylation in this tissue. Collectively, our findings reveal that Se-Met can promote proliferation and protein synthesis of myoblasts and skeletal muscle growth through ANXA2 phosphorylation.

Selenized Chickpea Sprouts Hydrolysates as a Potential Anti-Aging Ingredient

Skin aging represents a health and aesthetic problem that could result in infections and skin diseases. Bioactive peptides can potentially be used in skin aging regulation. Chickpea (Cicer arietinum L.) selenoproteins were obtained from germination with 2 mg Na₂SeO₃/100 g of seeds for 2 days. Alcalase, pepsin, and trypsin were used as hydrolyzers, and a membrane < 10 kDa was used to fractionate the hydrolysate. Se content, antioxidant capacity, elastase and collagen inhibition, functional stability, and preventative capacity were analyzed. Significant increases in Se content were found in germinated chickpea flour and protein related to the control. An increase of 38% in protein was observed in the selenized flour related to the control. A band (600-550 cm^-1) observed in the selenized hydrolysates suggested the insertion of Se into the protein. Hydrolysates from pepsin and trypsin had the highest antioxidant potential. Se enhanced the stability of total protein and protein hydrolysates through time and increased their antioxidant capacity. Hydrolysates > 10 kDa had higher elastase and collagenase inhibition than the total protein and hydrolysates < 10 kDa. Protein hydrolysates < 10 kDa 6 h before UVA radiation had the highest inhibition of collagen degradation. Selenized protein hydrolysates showed promising antioxidant effects that could be related to skin anti-aging effects.

Selenium Uptake, Translocation, and Metabolization Pattern during Barley Malting: A Comparison of Selenate, Selenite, and Selenomethionine

Selenium (Se) is an essential trace element for human and animal health. Understanding the uptake and translocation of Se in crops is critical from the perspective of Se biofortification. In this study, barley was malted to investigate the uptake, translocation, and metabolism of exogenous Se including Na2SeO4, Na2SeO3, and selenomethionine (Se-Met). The results showed that the uptake rates of different forms of Se in barley decreased in the following order: Se-Met > Na2SeO3 > Na2SeO4, with the peak uptake occurring at the end of the steeping stages. In the early stages of germination, Se was mainly distributed in the husk and endosperm. Exogenous Se upregulated the transcription levels of Se transport and metabolic enzyme genes in the barley to varying degrees, which promoted Se transformation in various tissues, and improved Se bioeffectiveness. Compared to the Na2SeO3 and Se-Met groups, more Se was transferred from husk and endosperm to acrospire and rootlets in the Na2SeO4 group during the germination stage. Na2SeO4 and Se-Met stimulated the development of rootlets, and accelerated Se metabolism, resulting in a higher Se loss rate. Thus, these comparative findings provide new insights into Se uptake, transformation, and metabolization in barley.

Selenium in Peptide Chemistry

In recent years, researchers have been exploring the potential of incorporating selenium into peptides, as this element possesses unique properties that can enhance the reactivity of these compounds. Selenium is a non-metallic element that has a similar electronic configuration to sulfur. However, due to its larger atomic size and lower electronegativity, it is more nucleophilic than sulfur. This property makes selenium more reactive toward electrophiles. One of the most significant differences between selenium and sulfur is the dissociation of the Se-H bond. The Se-H bond is more easily dissociated than the S-H bond, leading to higher acidity of selenocysteine (Sec) compared to cysteine (Cys). This difference in acidity can be exploited to selectively modify the reactivity of peptides containing Sec. Furthermore, Se-H bonds in selenium-containing peptides are more susceptible to oxidation than their sulfur analogs. This property can be used to selectively modify the peptides by introducing new functional groups, such as disulfide bonds, which are important for protein folding and stability. These unique properties of selenium-containing peptides have found numerous applications in the field of chemical biology. For instance, selenium-containing peptides have been used in native chemical ligation (NCL). In addition, the reactivity of Sec can be harnessed to create cyclic and stapled peptides. Other chemical modifications, such as oxidation, reduction, and photochemical reactions, have also been applied to selenium-containing peptides to create novel molecules with unique biological properties.

Selenium-enriched plant foods: Selenium accumulation, speciation, and health functionality

Selenium (Se) is an essential element for maintaining human health. The biological effects and toxicity of Se compounds in humans are related to their chemical forms and consumption doses. In general, organic Se species, including selenoamino acids such as selenomethionine (SeMet), selenocystine (SeCys₂), and Se-methylselenocysteine (MSC), could provide greater bioactivities with less toxicity compared to those inorganics including selenite (Se IV) and selenate (Se VI). Plants are vital sources of organic Se because they can accumulate inorganic Se or metabolites and store them as organic Se forms. Therefore, Se-enriched plants could be applied as human food to reduce deficiency problems and deliver health benefits. This review describes the recent studies on the enrichment of Se-containing plants in particular Se accumulation and speciation, their functional properties related to human health, and future perspectives for developing Se-enriched foods. Generally, Se's concentration and chemical forms in plants are determined by the accumulation ability of plant species. Brassica family and cereal grains have excessive accumulation capacity and store major organic Se compounds in their cells compared to other plants. The biological properties of Se-enriched plants, including antioxidant, anti-diabetes, and anticancer activities, have significantly presented in both in vitro cell culture models and in vivo animal assays. Comparatively, fewer human clinical trials are available. Scientific investigations on the functional health properties of Se-enriched edible plants in humans are essential to achieve in-depth information supporting the value of Se-enriched food to humans.

Selenium-enriched foods and their ingredients: As intervention for the vicious cycle between autophagy and overloaded stress responses in Alzheimer's disease

Dysfunctional autophagy induced by excessive reactive oxygen species (ROS) load and inflammation accelerates the development of Alzheimer's disease (AD). Recently, there has been an increasing interest in selenium-enriched ingredients (SEIs), such as selenoproteins, selenoamino acids and selenosugars, which could improve AD through antioxidant and anti-inflammation, as well as autophagy modulating effects. This review indicates that SEIs eliminate excessive ROS by activating the nuclear translocation of nuclear factor erythroid2-related factor 2 (Nrf2) and alleviate inflammation by inhibiting the mitogen-activated protein kinases (MAPKs)/nuclear factor kappa-B (NF-κB) pathway. Furthermore, they can activate the adenosine 5'-monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway, and subsequently promote amyloid beta (Aβ) clearance and reduce memory impairments. SEIs are ubiquitous in many plants and microorganisms, such as Brassicaceae vegetables, yeast, and mushroom. Enzymatic hydrolysis, as well as physical processing, such as thermal, high pressure and microwave treatment, are the main techniques to modify the properties of dietary selenium. This work highlights the fact that SEIs can inhibit inflammation and oxidative stress and provides evidence that supports the potential use of these dietary materials to be a novel strategy for improving AD.

A Review of Plant Selenium-Enriched Proteins/Peptides: Extraction, Detection, Bioavailability, and Effects of Processing

As an essential trace element in the human body, selenium (Se) has various physiological activities, such as antioxidant and anticancer activity. Selenium-enriched proteins/peptides (SePs/SePPs) are the primary forms of Se in plants and animals, and they are the vital carriers of its physiological activities. On the basis of current research, this review systematically describes the extraction methods (aqueous, alkaline, enzymatic, auxiliary, etc.) and detection methods (HPLC-MS/MS, GC-ICP-MS, etc.) for SePs/SePPs in plants. Their bioavailability and bioactivity, and the effect of processing are also included. Our review provides a comprehensive understanding and theoretical guidance for the utilization of selenium-enriched proteins/peptides.

Recent Progress in Cyclic Aryliodonium Chemistry: Syntheses and Applications

Hypervalent aryliodoumiums are intensively investigated as arylating agents. They are excellent surrogates to aryl halides, and moreover they exhibit better reactivity, which allows the corresponding arylation reactions to be performed under mild conditions. In the past decades, acyclic aryliodoniums are widely explored as arylation agents. However, the unmet need for acyclic aryliodoniums is the improvement of their notoriously low reaction economy because the coproduced aryl iodides during the arylation are often wasted. Cyclic aryliodoniums have their intrinsic advantage in terms of reaction economy, and they have started to receive considerable attention due to their valuable synthetic applications to initiate cascade reactions, which can enable the construction of complex structures, including polycycles with potential pharmaceutical and functional properties. Here, we are summarizing the recent advances made in the research field of cyclic aryliodoniums, including the nascent design of aryliodonium species and their synthetic applications. First, the general preparation of typical diphenyl iodoniums is described, followed by the construction of heterocyclic iodoniums and monoaryl iodoniums. Then, the initiated arylations coupled with subsequent domino reactions are summarized to construct polycycles. Meanwhile, the advances in cyclic aryliodoniums for building biaryls including axial atropisomers are discussed in a systematic manner. Finally, a very recent advance of cyclic aryliodoniums employed as halogen-bonding organocatalysts is described.

The Integral Boosting Effect of Selenium on the Secondary Metabolism of Higher Plants

Selenium is a micronutrient with a wide range of functions in animals, including humans, and in microorganisms such as microalgae. However, its role in plant metabolism remains ambiguous. Recent studies of Se supplementation showed that not only does it increase the content of the element itself, but also affects the accumulation of secondary metabolites in plants. The purpose of this review is to analyze and summarize the available data on the place of selenium in the secondary metabolism of plants and its effect on the accumulation of some plant metabolites (S- and N-containing secondary metabolites, terpenes, and phenolic compounds). In addition, possible molecular mechanisms and metabolic pathways underlying these effects are discussed. It should be noted that available data on the effect of Se on the accumulation of secondary metabolites are inconsistent and contradictory. According to some studies, selenium has a positive effect on the accumulation of certain metabolites, while other similar studies show a negative effect or no effect at all. The following aspects were identified as possible ways of regulating plant secondary metabolism by Se-supplementation: changes occurring in primary S/N metabolism, hormonal regulation, redox metabolism, as well as at the transcriptomic level of secondary metabolite biosynthesis. In all likelihood, the confusion in the results can be explained by other, more complex regulatory mechanisms in which selenium is involved and which affect the production of metabolites. Further study on the involvement of various forms of selenium in metabolic and signaling pathways is crucial for a deeper understanding of its role in growth, development, and health of plants, as well as the regulatory mechanisms behind them.

Comparison of an Artificial Neural Network and a Response Surface Model during the Extraction of Selenium-Containing Protein from Selenium-Enriched Brassica napus L

In this study, the extraction conditions for selenium-enriched rape protein (SEP) were optimized by applying a response surface methodology (RSM) and artificial neural network (ANN) model, and then, the optimal conditions were obtained using a genetic algorithm (GA). Then, the antioxidant power of the SEP was examined by using the DPPH, ABTS, and CCK-8 (Cell Counting Kit-8), and its anticancer activities were explored by conducting a cell migration test. The results showed that compared with the RSM model, the ANN model was more accurate with a higher determination coefficient and fewer errors when it was applied to optimize the extraction method. The data obtained for SEP using a GA were as follows: the extraction temperature was 59.4 °C, the extraction time was 3.0 h, the alkaline concentration was 0.24 mol/L, the liquid-to-material ratio was 65.2 mL/g, and the predicted content of protein was 58.04 mg/g. The protein was extracted under the conditions obtained by the GA; the real content of protein was 57.69 mg/g, and the protein yield was 61.71%. Finally, as the concentration of the selenium-containing protein increased, it showed increased ability in scavenging free radicals and was influential in inhibiting the proliferation and migration of HepG2 cells.

Selenium: An Antioxidant with a Critical Role in Anti-Aging

Aging is characterized by an imbalance between damage inflicted by reactive oxygen species (ROS) and the antioxidative defenses of the organism. As a significant nutritional factor, the trace element selenium (Se) may remodel gradual and spontaneous physiological changes caused by oxidative stress, potentially leading to disease prevention and healthy aging. Se is involved in improving antioxidant defense, immune functions, and metabolic homeostasis. An inadequate Se status may reduce human life expectancy by accelerating the aging process or increasing vulnerability to various disorders, including immunity dysfunction, and cancer risk. This review highlights the available studies on the effective role of Se in aging mechanisms and shows the potential clinical implications related to its consumption. The main sources of organic Se and the advantages of its nanoformulations were also discussed.

Identification and Immunomodulatory Effect on Immunosuppressed Mice of Selenium-Enriched Peptides of Egg White

Selenium-enriched egg white peptides (Se-EWP) were prepared by pre-heat treatment and enzymatic hydrolysis in this study. In addition, their selenopeptide sequence identification and immunomodulatory effect were investigated. Results showed that the yield of Se-EWP obtained from alkaline-neutral protease treatment reached 76.90%, and peptides with a molecular weight of 200-1000 Da accounted for 98.33%. Four characteristic selenopeptides, including SeCys-Trp-Leu-Glu, Trp-Ser-SeCys, SeMet-Ala-Pro, and SeMet-Leu, were identified by HPLC-ESI-MS/MS, which were rich in hydrophobic and branched-chain amino acids. Se-EWP (750 mg/kg/d) could effectively retard the decrease of immune organ index in immunosuppressed mice induced by cyclophosphamide. Moreover, supplementation of Se-EWP could promote a higher content of Se in liver, the number of white blood cells, and the levels of serum cytokines (IL-6, IL-2, and TNF-α) as compared with EWP groups, indicating that Se-EWP could effectively alleviate immunosuppression induced by cyclophosphamide. These findings suggested that Se-EWP exhibited great potential as functional foods for immunomodulatory effect.

Selenium-Enriched Black Soybean Protein Prevents Benzo(a)pyrene-Induced Pyroptotic Colon Damage and Gut Dysbacteriosis

Selenium-enriched black soybean protein (SeBSP) is a kind of high-quality selenium resource with many physiological functions. Benzo(a)pyrene (BaP) is a well-known injurant that widely exists in high-temperature processed food and has been previously found to cause colon injury. In this study, the effects of SeBSP on colonic damage induced by BaP in BALB/C mice were investigated by comparing it with normal black soybean protein (BSP). SeBSP inhibited the BaP-induced reductions on body weight, food intake, and water intake. Moreover, metabolic enzymes, including AhR, CYP1A1, CYP1B1, and GST-P1, that were promoted by BaP were downregulated by SeBSP, reducing oxidative damage caused by BaP in the metabolic process. The classical pyroptosis indexes (i.e., NLRP3, ASC, Caspase-1, GSDMD) and inflammatory factors (i.e., TNF-α, IL-1β, IL-18, iNOS, COX-2) were downregulated by SeBSP in BaP-treated mice, suggesting the benefits of SeBSP in reducing colonic toxicity. Notably, SeBSP enhanced microbial diversity of gut microbiota and increased relative abundances of prebiotic bacteria, for example, Lactobacillus reuteri, Bacteroides thetaiotaomicron, and genera Bifidobacterium, and Blautia, along with the promotion of short-chain fatty acids. Integrative analysis showed strong links between the antioxidant and anti-inflammatory effects of SeBSP and its altered gut microbiota. Collectively, our study demonstrates the pronounced benefits of Se-enriched black soybean in preventing the colonic toxicity of BaP, and such effects could be mediated by gut microbiota.

Biogenic Selenium Nanoparticles and Their Anticancer Effects Pertaining to Probiotic Bacteria—A Review

Selenium nanoparticles (SeNPs) can be produced by biogenic, physical, and chemical processes. The physical and chemical processes have hazardous effects. However, biogenic synthesis (by microorganisms) is an eco-friendly and economical technique that is non-toxic to human and animal health. The mechanism for biogenic SeNPs from microorganisms is still not well understood. Over the past two decades, extensive research has been conducted on the nutritional and therapeutic applications of biogenic SeNPs. The research revealed that biogenic SeNPs are considered novel competitors in the pharmaceutical and food industries, as they have been shown to be virtually non-toxic when used in medical practice and as dietary supplements and release only trace amounts of Se ions when ingested. Various pathogenic and probiotic/nonpathogenic bacteria are used for the biogenic synthesis of SeNPs. However, in the case of biosynthesis by pathogenic bacteria, extraction and purification techniques are required for further useful applications of these biogenic SeNPs. This review focuses on the applications of SeNPs (derived from probiotic/nonpathogenic organisms) as promising anticancer agents. This review describes that SeNPs derived from probiotic/nonpathogenic organisms are considered safe for human consumption. These biogenic SeNPs reduce oxidative stress in the human body and have also been shown to be effective against breast, prostate, lung, liver, and colon cancers. This review provides helpful information on the safe use of biogenic SeNPs and their economic importance for dietary and therapeutic purposes, especially as anticancer agents.

Turning gray selenium into a nanoaccelerator of tissue regeneration by PEG modification

Selenium (Se) is an essential trace element involved in nearly all human physiological processes but suffers from a narrow margin between benefit and toxicity. The nanoform of selenium has been proven shown to be more bioavailable and less toxic, yet significant challenges remain regarding the efficient and feasible synthesis of biologically active nanoselenium. In addition, although nanoselenium has shown a variety of biological activities, more interesting nanoselenium features are expected. In this work, hydrosoluble nanoselenium termed Nano-Se in the zero oxidation state was synthesized between gray Se and PEG. A zebrafish screen was carried out in zebrafish larvae cocultured with Nano-Se. Excitingly, Nano-Se promoted the action of the FGFR, Wnt, and VEGF signaling pathways, which play crucial roles in tissue regeneration. As expected, Nano-Se not only achieved the regeneration of zebrafish tail fins and mouse skin but also promoted the repair of skin in diabetic mice while maintaining a profitable safe profile. In brief, the Nano-Se reported here provided an efficient and feasible method for bioactive nanoselenium synthesis and not only expanded the application of nanoselenium to regenerative medicine but also likely reinvigorated efforts for discovering more peculiarunique biofunctions of nanoselenium in a great variety of human diseases.

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It was found that selenium nanoparticles through FGFR、Wnt、VEGFR signal pathway to promote tissue regeneration;

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Development a new water-soluble, bio-compatible, zero oxidation state Nano-Se;

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Development a new efficient and safe nano-biologic agent for promoting tissue regeneration.