Organic selenium compounds as potential chemotherapeutic agents for improved cancer treatment

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.

Exposure to Selenomethionine and Selenocystine Induces Redox-Mediated ER Stress in Normal Breast Epithelial MCF-10A Cells

Selenium is an essential trace element co-translationally incorporated into selenoproteins with important biological functions. Health benefits have long been associated with selenium supplementation. However, cytotoxicity is observed upon excessive selenium intake. The aim of this study is to investigate the metabolic pathways underlying the response to the selenium-containing amino acids selenomethionine and selenocysteine in a normal human breast epithelial cell model. We show that both selenomethionine and selenocystine inhibit the proliferation of non-cancerous MCF-10A cells in the same concentration range as cancerous MCF-7 and Hela cells, which results in apoptotic cell death. Selenocystine exposure in MCF-10A cells caused a severe depletion of free low molecular weight thiols, which might explain the observed upregulation of the expression of the oxidative stress pathway transcription factor NRF2. Both selenomethionine and selenocystine induced the expression of target genes of the unfolded protein response (GRP78, ATF4, CHOP). Using a redox-sensitive fluorescent probe targeted to the endoplasmic reticulum (ER), we show that both selenoamino acids shifted the ER redox balance towards an even more oxidizing environment. These results suggest that alteration of the redox state of the ER may disrupt protein folding and cause ER stress-induced apoptosis in MCF-10A cells exposed to selenoamino acids.

Synthesis of selenophene-containing flavonols and 2-styrylchromones: Evaluation of their activities compared with selenophene-containing chalcones as potential anticancer agents

Previously, we documented the synthesis and assessed the biological effects of chalcones containing selenium against HT-29 human colorectal adenocarcinoma cells, demonstrating their significant potential. As research on selenium-containing flavonoids remains limited, this article outlines our design and synthesis of three selenium-based flavonols and three 2-styrylchromones. We conducted evaluations of these compounds to determine their impact on human lung cancer cells (A549, H1975, CL1-0, and CL1-5) and their influence on normal lung fibroblast MRC5 cells. Additionally, we included selenium-based chalcones in our testing for comparative purposes. Our findings highlight that the simplest compound, designated as compound 1, exhibited the most promising performance among the tested molecules.

An efficient methodological approach for synthesis of selenopyridines: generation, reactions, anticancer activity, EGFR inhibitory activity and molecular docking studies

In the present work, we successfully synthesized Se-alkyl selenopyridines 1 and 3, selenopheno[2,3-b]pyridine 2, and bis-selenopyridine 4 derivatives using an eco-friendly method by utilizing NaHSe instead of toxic hydrogen selenide. The effect of the temperature on the reaction was screening at various temperatures. The regiospecific reaction of selenopyridine 1 with bromine afforded an unexpected product 4,6-diamino-5-bromo-2-[(cyanomethyl)selenyl]-pyridine-3-carbonitrile (5), which was cyclized to selenopheno[2,3-b]pyridine (7) by refluxing in the presence of TEA. While its treatment with thiophenol and/or p-chlorothiophenol gave 8a, b. On the other hand, its reaction with aminothiophenol afforded 2-(benzo[d]-thiazol-2-yl)-5-bromoselenopheno[2,3-b]pyridine-3,4,6-triamine (9). Also, N-(2-cyano-4-methyl-5H-1-seleno-3,5,8-triazaacenaphthylen-7-yl)acetamide (11) and a novel series of selenoazo dyes 12a-d were synthesized by treatment of selenopheno[2,3-b]pyridine 2 with acetic anhydride and/or diazonium chlorides of aromatic amines, respectively. Then, we ascertained the potential activity of synthesized compounds against highly metastatic prostate cancer cells (PC-3) and osteosarcoma cells (MG-63) and found that 12a, 12b, 12c, and 12d were more cytotoxic than doxorubicin in both tested cell lines, showing nearly the same anticancer activity with IC50 values ranging from 2.59 ± 0.02 µM to 3.93 ± 0.23 µM. Mechanistically, the most potent compounds 12a and 12b proved to be potent EGFR inhibitors with IC50 values of 0.301 and 0.123 µM, respectively, compared to lapatinib as a positive reference (IC50 = 0.049 µM). Moreover, the docking results are in good agreement with the anticancer activity as well as the EGFR inhibitory activity, suggesting these two compounds as promising EGFR anticancer candidates.

Development of novel transition metal-catalyzed synthetic approaches for the synthesis of a dihydrobenzofuran nucleus: a review

The synthesis of dihydrobenzofuran scaffolds bears pivotal significance in the field of medicinal chemistry and organic synthesis. These heterocyclic scaffolds hold immense prospects owing to their significant pharmaceutical applications as they are extensively employed as essential precursors for constructing complex organic frameworks. Their versatility and importance make them an interesting subject of study for researchers in the scientific community. While exploring their synthesis, researchers have unveiled various novel and efficient pathways for assembling the dihydrobenzofuran core. In the wake of extensive data being continuously reported each year, we have outlined the recent updates (post 2020) on novel methodological accomplishments employing the efficient catalytic role of several transition metals to forge dihydrobenzofuran functionalities.

Selenosugar, selenopolysaccharide, and putative selenoflavonoid in plants

Selenium (Se) is a naturally occurring essential micronutrient that is required for human health. Selenium supports cellular antioxidant defense and possesses bioeffects such as anti-inflammation, anti-cancer, anti-diabetic, and cardiovascular and liver protective effects arising from Se-enhanced cellular antioxidant activity. Past studies on Se have focused on elucidating Se speciation in foods, biofortification strategies to produce Se-enriched foods to address Se deficiency in the population, and the biochemical activities of Se in health. The bioavailability and toxicity of Se are closely correlated to its chemical forms and may exhibit varying effects on body physiology. Selenium exists in inorganic and organic forms, in which inorganic Se such as sodium selenite and sodium selenate is more widely available. However, it is a challenge for safe and effective supplementation considering inorganic Se low bioavailability and high cytotoxicity. Organic Se, by contrast, exhibits higher bioavailability and lower toxicity and has a more diverse composition and structure. Organic Se exists as selenoamino acids and selenoproteins, but recent research has provided evidence that it also exists as selenosugars, selenopolysaccharides, and possibly as selenoflavonoids. Different food categories contain various Se compounds, and their Se profiles vary significantly. Therefore, it is necessary to delineate Se speciation in foods to understand their impact on health. This comprehensive review documents our knowledge of the recent uncovering of the existence of selenosugars and selenopolysaccharides and the putative evidence for selenoflavonoids. The bioavailability and bioactivities of these food-derived organic Se compounds are highlighted, in addition to their composition, structural features, and structure-activity relationships.

Co-Delivery of an Innovative Organoselenium Compound and Paclitaxel by pH-Responsive PCL Nanoparticles to Synergistically Overcome Multidrug Resistance in Cancer

In this study, we designed the association of the organoselenium compound 5'-Seleno-(phenyl)-3'-(ferulic-amido)-thymidine (AFAT-Se), a promising innovative nucleoside analogue, with the antitumor drug paclitaxel, in poly(ε-caprolactone) (PCL)-based nanoparticles (NPs). The nanoprecipitation method was used, adding the lysine-based surfactant, 77KS, as a pH-responsive adjuvant. The physicochemical properties presented by the proposed NPs were consistent with expectations. The co-nanoencapsulation of the bioactive compounds maintained the antioxidant activity of the association and evidenced greater antiproliferative activity in the resistant/MDR tumor cell line NCI/ADR-RES, both in the monolayer/two-dimensional (2D) and in the spheroid/three-dimensional (3D) assays. Hemocompatibility studies indicated the safety of the nanoformulation, corroborating the ability to spare non-tumor 3T3 cells and human mononuclear cells of peripheral blood (PBMCs) from cytotoxic effects, indicating its selectivity for the cancerous cells. Furthermore, the synergistic antiproliferative effect was found for both the association of free compounds and the co-encapsulated formulation. These findings highlight the antitumor potential of combining these bioactives, and the proposed nanoformulation as a potentially safe and effective strategy to overcome multidrug resistance in cancer therapy.

The Potential of Integrative Cancer Treatment Using Melatonin and the Challenge of Heterogeneity in Population-Based Studies: A Case Report of Colon Cancer and a Literature Review

Melatonin is a multifunctional hormone regulator that maintains homeostasis through circadian rhythms, and desynchronization of these rhythms can lead to gastrointestinal disorders and increase the risk of cancer. Preliminary clinical studies have shown that exogenous melatonin alleviates the harmful effects of anticancer therapy and improves quality of life, but the results are still inconclusive due to the heterogeneity of the studies. A personalized approach to testing clinical parameters and response to integrative treatment with nontoxic and bioavailable melatonin in patient-centered N-of-1 studies deserves greater attention. This clinical case of colon cancer analyzes and discusses the tumor pathology, the adverse effects of chemotherapy, and the dynamics of markers of inflammation (NLR, LMR, and PLR ratios), tumors (CEA, CA 19-9, and PSA), and hemostasis (D-dimer and activated partial thromboplastin time). The patient took melatonin during and after chemotherapy, nutrients (zinc, selenium, vitamin D, green tea, and taxifolin), and aspirin after chemotherapy. The patient's PSA levels decreased during CT combined with melatonin (19 mg/day), and melatonin normalized inflammatory markers and alleviated symptoms of polyneuropathy but did not help with thrombocytopenia. The results are analyzed and discussed in the context of the literature on oncostatic and systemic effects, alleviating therapy-mediated adverse effects, association with survival, and N-of-1 studies.

Data of radiation damage on selenomethionine-substituted single-domain substrate-binding protein

Radiation damage is an inherent issue in X-ray crystallography. It not only damages macromolecular crystals, which lowers the quality of the diffraction intensity, but results in inaccurate structural information. Among the various types of radiation damage, little is known regarding the damage to selenomethionine, an amino acid contained in some proteins. Recently, radiation damage to the selenomethionine-substituted single-domain substrate-binding domain from Rhodothermus marinus (SeMet-RmSBP) was investigated. Global and specific radiation damage from four datasets collected by repeatedly exposing a single RmSBP-SeMet crystal to X-rays were analyzed. The results indicated that the B-factor value of the selenium atom in selenomethionine was significantly increased compared with other atoms. To date, no images of radiation damage have been reported for selenomethionine-substituted proteins. Therefore, these data may be used to study radiation damage in macromolecular crystallography. This study provides insight into radiation damage associated with selenomethionine.

Diphenyl Diselenide Through Reduction of Inflammation, Oxidative Injury and Caspase-3 Activation Abates Doxorubicin-Induced Neurotoxicity in Rats

Neurotoxicity associated with chemotherapy is a debilitating side effect of cancer management in humans which reportedly involves inflammatory and oxidative stress responses. Diphenyl diselenide (DPDS) is an organoselenium compound which exhibits its anti-tumoral, anti-oxidant, anti-inflammatory and anti-mutagenic effects. Nevertheless, its possible effect on chemotherapy-induced neurotoxicity is not known. Using rat model, we probed the behavioral and biochemical effects accompanying administration of antineoplastic agent doxorubicin (7.5 mg/kg) and DPDS (5 and 10 mg/kg). Anxiogenic-like behavior, motor and locomotor insufficiencies associated with doxorubicin were considerably abated by both DPDS doses with concomitant enhancement in exploratory behavior as demonstrated by reduced heat maps intensity and enhanced track plot densities. Moreover, with exception of cerebral glutathione (GSH) level, superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities, biochemical data demonstrated reversal of doxorubicin-mediated decline in cerebral and cerebellar antioxidant status indices and the increase in acetylcholinesterase (AChE) activity by both doses of DPDS. Also, cerebellar and cerebral lipid peroxidation, hydrogen peroxide as well as reactive oxygen and nitrogen species levels were considerably diminished in rats administered doxorubicin and DPDS. In addition, DPDS administration abated myeloperoxidase activity, tumour necrosis factor alpha and nitric oxide levels along with caspase-3 activity in doxorubicin-administered rats. Chemoprotection of doxorubicin-associated neurotoxicity by DPDS was further validated by histomorphometry and histochemical staining. Taken together, DPDS through offsetting of oxido-inflammatory stress and caspase-3 activation elicited neuroprotection in doxorubicin-treated rats.

Nanomaterials-Induced Redox Imbalance: Challenged and Opportunities for Nanomaterials in Cancer Therapy

Cancer cells typically display redox imbalance compared with normal cells due to increased metabolic rate, accumulated mitochondrial dysfunction, elevated cell signaling, and accelerated peroxisomal activities. This redox imbalance may regulate gene expression, alter protein stability, and modulate existing cellular programs, resulting in inefficient treatment modalities. Therapeutic strategies targeting intra- or extracellular redox states of cancer cells at varying state of progression may trigger programmed cell death if exceeded a certain threshold, enabling therapeutic selectivity and overcoming cancer resistance to radiotherapy and chemotherapy. Nanotechnology provides new opportunities for modulating redox state in cancer cells due to their excellent designability and high reactivity. Various nanomaterials are widely researched to enhance highly reactive substances (free radicals) production, disrupt the endogenous antioxidant defense systems, or both. Here, the physiological features of redox imbalance in cancer cells are described and the challenges in modulating redox state in cancer cells are illustrated. Then, nanomaterials that regulate redox imbalance are classified and elaborated upon based on their ability to target redox regulations. Finally, the future perspectives in this field are proposed. It is hoped this review provides guidance for the design of nanomaterials-based approaches involving modulating intra- or extracellular redox states for cancer therapy, especially for cancers resistant to radiotherapy or chemotherapy, etc.

Design, synthesis, and bioactivity evaluation of novel indole-selenide derivatives as P-glycoprotein inhibitors against multi-drug resistance in MCF-7/ADR cell

The inhibition of P-glycoprotein (P-gp) has emerged as an intriguing strategy for circumventing multidrug resistance (MDR) in anticancer chemotherapy. In this study, we have designed and synthesized 30 indole-selenides as a new class of P-gp inhibitors based on the scaffold hopping strategy. Among them, the preferred compound H27 showed slightly stronger reversal activity (reversal fold: 271.7 vs 261.6) but weaker cytotoxicity (inhibition ratio: 33.7% vs 45.1%) than the third-generation P-gp inhibitor tariquidar on the tested MCF-7/ADR cells. Rh123 accumulation experiments and Western blot analysis demonstrated that H27 displayed excellent MDR reversal activity by dose-dependently inhibiting the efflux function of P-gp rather than its expression. Besides, UIC-2 reactivity shift assay revealed that H27 could bind to P-gp directly and induced a conformation change of P-gp. Moreover, docking study revealed that H27 matched well in the active pockets of P-gp by forming some key H-bonding interactions, arene-H interactions and hydrophobic contacts. These results suggested that H27 is worth to be a starting point for the development of novel Se-containing P-gp inhibitors for clinic use.

Synthesis, antitumor activity evaluation of 2-selenocyano-3-selenocyanoalkyloxyestradiols with a bisselenocyanate structure

The combination of steroid structure and selenocyano group offers high potential for the design and synthesis of new potential anti-tumor drugs. Beginning with estradiol, a series of 2-selenocyano-3-selenocyanoalkyloxyestradiol derivatives with remarkable antiproliferative activity was synthesized. Additionally, a 2,4-bisselenocyanoestradiol was synthesized by directly selenocyanating estradiol diacetate. It was found that the cytotoxicity of 2-selenocyano-3-selenocyanoalkyloxyestradiol derivatives was significantly increased in comparison to the corresponding monoselenocyanate precursor, whereas the cytotoxicity of the 2, 4-bisselenocyanoestradiol derivative was significantly reduced compared to the respective monosubstituted precursor. The introduction of the second selenocyano group at different locations of estradiol shows a various impact on the cytotoxicity of the compounds. Among them, compound 3e showed the best cytotoxicity, with an IC50 value of less than 5 μM against the tested tumor cells, and strong inhibitory activities against HeLa and MCF-7 cell xenograft tumors in zebrafish, suppressing tumor cell migration and neovascularization. Notably, compound 3e was more effective at inhibiting neovascularization of MCF-7 cell xenograft tumors than the positive control 2-methoxyestradiol. Furthermore, compound 3e showed excellent anti-oxidative stress effect in zebrafish. Therefore, these estrogen bisselenocyanate compounds may be promising anti-tumor agents, warranting further investigation.

Seleno-Warfare against Cancer: Decoding Antitumor Activity of Novel Acylselenoureas and Se-Acylisoselenoureas

Currently, cancer remains a global health problem. Despite the existence of several treatments, including chemotherapy, immunotherapy, and radiation therapy, the survival rate for most cancer patients, particularly those with metastasis, remains unsatisfactory. Thus, there is a continuous need to develop novel, effective therapies. In this work, 22 novel molecules containing selenium are reported, including seven Se-acylisoselenoureas synthesized from aliphatic carbodiimides as well as acylselenoureas with the same carbo- and heterocycles and aliphatic amines. After an initial screening at two doses (50 and 10 µM) in MDA-MB-231 (breast), HTB-54 (lung), DU-145 (prostate), and HCT-116 (colon) tumor cell lines, the ten most active compounds were identified. Additionally, these ten hits were also submitted to the DTP program of the NCI to study their cytotoxicity in a panel of 60 cancer cell lines. Compound 4 was identified as the most potent antiproliferative compound. The results obtained showed that compound 4 presented IC50 values lower than 10 µM in the cancer cell lines, although it was not the most selective one. Furthermore, compound 4 was found to inhibit cell growth and cause cell death by inducing apoptosis partially via ROS production. Overall, our results suggest that compound 4 could be a potential chemotherapeutic drug for different types of cancer.

Formulation Studies with Cyclodextrins for Novel Selenium NSAID Derivatives

Commercial cyclodextrins (CDs) are commonly used to form inclusion complexes (ICs) with different molecules in order to enhance their water solubility, stability, and bioavailability. Nowadays, there is strong, convincing evidence of the anticancer effect of selenium (Se)-containing compounds. However, pharmaceutical limitations, such as an unpleasant taste or poor aqueous solubility, impede their further evaluation and clinical use. In this work, we study the enhancement of solubility with CD complexes for a set of different nonsteroidal anti-inflammatory drug (NSAID) derivatives with Se as selenoester or diacyl diselenide chemical forms, with demonstrated antitumoral activity. The CD complexes were analyzed via nuclear magnetic resonance (NMR) spectroscopic techniques. In order to obtain additional data that could help explain the experimental results obtained, 3D models of the theoretical CD-compound complexes were constructed using molecular modeling techniques. Among all the compounds, I.3e and II.5 showed a remarkable increase in their water solubility, which could be ascribed to the formation of the most stable interactions with the CDs used, in agreement with the in silico studies performed. Thus, the preliminary results obtained in this work led us to confirm the selection of β and γ-CD as the most suitable for overcoming the pharmaceutical drawbacks of these Se derivatives.

3D-printed tri-element-doped hydroxyapatite/ polycaprolactone composite scaffolds with antibacterial potential for osteosarcoma therapy and bone regeneration

The resection of malignant osteosarcoma often results in large segmental bone defects, and the residual cells can facilitate recurrence. Consequently, the treatment of osteosarcoma is a major challenge in clinical practice. The ideal goal of treatment for osteosarcoma is to eliminate it thoroughly, and repair the resultant bone defects as well as avoid bacterial infections. Herein, we fabricated a selenium/strontium/zinc-doped hydroxyapatite (Se/Sr/Zn-HA) powder by hydrothermal method, and then employed it with polycaprolactone (PCL) as ink to construct composite scaffolds through 3D printing, and finally introduced them in bone defect repair induced by malignant osteosarcoma. The resultant composite scaffolds integrated multiple functions involving anti-tumor, osteogenic, and antibacterial potentials, mainly attributed to the anti-tumor effects of SeO32-, osteogenic effects of Sr2+ and Zn2+, and antibacterial effects of SeO32- and Zn2+. In vitro studies confirmed that Se/Sr/Zn-HA leaching solution could induce apoptosis of osteosarcoma cells, differentiation of MSCs, and proliferation of MC3T3-E1 while showing excellent antibacterial properties. In vivo tests demonstrated that Se/Sr/Zn-HA could significantly suppress tumors after 8 days of injection, and the Se/Sr/Zn-HA-PCLs scaffold repaired femoral defects effectively after 3 months of implantation. Summarily, the Se/Sr/Zn-HA-PCLs composite scaffolds developed in this study were effective for tumor treatment, bone defect repair, and post-operative anti-infection, which provided a great potential to be a facile therapeutic material for osteosarcoma resection.

Synthesis of Selenium Nanoparticles and Their Effect on Pancreatic Functions and Acute Pancreatitis in Rats

Acute pancreatitis (AP) have been documented to have severe impact on pancreatic function. Frequent incidence of AP can result in chronic pancreatitis and thereby it can increase the probability of pancreatic cancers. This study intended to examine the effect of selenium nanoparticles (Se-NPs) synthesized from Coleus forskohlii leaf extract on pancreatic function and AP in rat. Primarily, Se-NPs was fabricated using the C. forskohlii leaf extract. The synthesized nanomaterial was characterized through UV-visible, XRD, and FTIR spectroscopies. Notably, the zeta potential of Se-NPs was found to be -32.8 mV with a polydispersity index (PDI) of 0.18. Morphological analysis on SEM unveiled the spherical shape of Se-NP with an average particle size of 12.69 nm. Strikingly, cytotoxicity analysis on pancreatic cancer and normal cells unveiled the concentration-dependent toxicity profile. However, IC 50 value is lower in normal pancreatic cell lines in comparison to pancreatic cancer cells lines. Assessment of Se-NPs on AP rats revealed the positive impact of Se-NPs. It effectively decreased the amount of lipase, amylase, IL-1β, MDA, NO, and Bcl-2 while increased the glucose, insulin, HOMA-β and antioxidant potential in AP rats. In addition, an evaluation of Se-NPs in the pancreatic functions revealed the non-harmful effect of Se-NPs.

Environmental selenium and human longevity: An ecogeochemical perspective

Selenium (Se) has been called the "longevity element" by the scientific community because it has anti-cancer, anti-inflammatory, and anti-oxidant activity in humans. The geochemical properties and biological functions of Se have been widely studied in various fields, including geology, agriculture, and medicine. Bama Yao Autonomous County (Bama), a typical township in China with high longevity among the population, was selected as the research area. The present study organically combines the geological background, dietary structure, absorption and metabolism, and other biogeochemical aspects to comprehensively analyze the anti-aging properties of Se under high-Se conditions and a fiber-rich polysaccharide diet. Biogeochemical samples of surface soil, food, human hair, and urine were systematically collected from the environment and the residents, and the content and speciation of Se were analyzed. Concentrations of Se in the soil were moderate to high for Bama, with high-Se soil in 77.21% of the samples. Water-soluble Se concentrations were also high, 90% of the samples with moderate to high Se, and had a significant positive correlation with Se concentrations in crops. With both high total and high available Se, dietary samples from the study area showed Se-enriched characteristics. Accordingly, Se intake was also high (82.54 μg/d) in the population, strongly maintaining the normal bodily functions of the elderly. Accumulation and metabolism of Se in the population were assessed based on concentrations of Se in the hair and urine of residents over 60 years old. Continuous accumulation of Se was found to occur from 71 to 80 years of age. Concentrations of Se in residents under 71 years old and over 80 years old were in a state of loss. Overall, Se absorption and metabolism are maintained at the optimal physiological state, which is one of the primary factors maintaining the health and longevity of the elderly people in the study area.

Selenoproteins in Health

Selenium (Se) is a naturally occurring essential micronutrient that is required for human health. The existing form of Se includes inorganic and organic. In contrast to the inorganic Se, which has low bioavailability and high cytotoxicity, organic Se exhibits higher bioavailability, lower toxicity, and has a more diverse composition and structure. This review presents the nutritional benefits of Se by listing and linking selenoprotein (SeP) functions to evidence of health benefits. The research status of SeP from foods in recent years is introduced systematically, particularly the sources, biochemical transformation and speciation, and the bioactivities. These aspects are elaborated with references for further research and utilization of organic Se compounds in the field of health.

Absorption, Distribution, Metabolism, and Excretion of [14C]BS1801, a Selenium-Containing Drug Candidate, in Rats

BS1801 is a selenium-containing drug candidate with potential for treating liver and lung fibrosis. To fully elucidate the biotransformation of BS1801 in animals and provide sufficient preclinical drug metabolism data for human mass balance study, the metabolism of BS1801 in rats was investigated. We used radiolabeling techniques to investigate the mass balance, tissue distribution, and metabolite identification of BS1801 in Sprague-Dawley/Long-Evans rats after a single oral dose of 100 mg/kg (100 μCi/kg) [14C]BS1801: 1. The mean recovery of radioactive substances in urine and feces was 93.39% within 168 h postdose, and feces were the main excretion route. 2. Additionally, less than 1.00% of the dose was recovered from either urine or bile. 3. BS1801-related components were widely distributed throughout the body. 4. Fifteen metabolites were identified in rat plasma, urine, feces, and bile, and BS1801 was detected only in feces. 5. BS1801-M484, the methylation product obtained via a N-Se bond reduction in BS1801, was the most abundant drug-related component in plasma. The main metabolic pathways of BS1801 were reduction, amide hydrolysis, oxidation, and methylation. Overall, BS1801 was distributed throughout the body, and excreted mainly as an intact BS1801 form through feces. No differences were observed between male and female rats in distribution, metabolism, and excretion of BS1801.

Selenium Dibromide Click Chemistry: The Efficient Synthesis of Novel Selenabicyclo[3.3.1]nonene-2 and -nonane Derivatives

Highly efficient and convenient methods for the preparation of 35 novel derivatives of 9-selenabicyclo[3.3.1]nonane and 9-selenabicyclo[3.3.1]nonene-2 in high yields based on the adduct of the transannular addition of SeBr2 to 1,5-cyclooctadiene were developed. The methods for the amination of the adduct made it possible to obtain both diamino selenabicyclo[3.3.1]nonane derivatives and their dihydrobromide salts in one step in 88-98% yields. The methods meet the criteria of click chemistry. Compounds with high glutathione peroxidase mimetic activity were found among water-soluble dihydrobromide salts. The selective reaction of 2,6-dibromo-9-selenabicyclo[3.3.1]nonane with acetonitrile to form 6-bromo-9-selenabicyclo[3.3.1]nonene-2 was discovered. The latter compound served as a promising starting material to give rise to the new class of selenabicyclo[3.3.1]nonene-2 derivatives, e.g., 6-alkoxy-9-selenabicyclo[3.3.1]nonenes were obtained in 94-99% yields.

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

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

Critical assessment of selenourea as an efficient small molecule fluorescence quenching probe to monitor protein dynamics

Organoselenium compounds have recently been the experimentalists' delight due to their broad applications in organic synthesis, medicinal chemistry, and materials science. Selenium atom replacement of the carbonyl oxygen of the urea moiety dramatically reduces the HOMO-LUMO gap and oxidation potential, which completely changes the physicochemical properties of selenocarbonyl compounds. To our surprise, the photophysics and utility of a simple molecule such as selenourea (SeU) have not been explored in detail, which persuaded us to investigate its role in excited state processes. The steady-state emission, temperature-dependent time-correlated single photon counting, and femtosecond fluorescence upconversion experimental results confirmed that SeU significantly enhances the fluorescence quenching through a photoinduced electron transfer (PET) mechanism with an ∼10 ps ultrafast intrinsic PET lifetime component which is mostly absent in thiourea (TU). A wide range of fluorophores, based on their different redox abilities and fluorescence lifetimes covering a broad spectral window (λex: 390-590 nm and λem: 490-690 nm), were chosen to validate the proof of the concept. It was extended to tetramethylrhodamine (TMR)-5-maleimide labeled lysozyme protein, where we observed significant fluorescence quenching in the presence of SeU. The present work emphasizes that the high quenching efficiency with an ultrafast PET process, reduced orbital energy gap, and higher negative free energy change of the electron transfer reaction are the representative characteristics of selenourea or selenoamides to enable them as potential surrogates of thioamides or oxoamides quenching probes to monitor protein conformational changes and dynamics.

Organic Selenium induces ferroptosis in pancreatic cancer cells

Pancreatic ductal adenocarcinoma (PDA) cells reprogram both mitochondrial and lysosomal functions to support growth. At the same time, this causes significant dishomeostasis of free radicals. While this is compensated by the upregulation of detoxification mechanisms, it also represents a potential vulnerability. Here we demonstrate that PDA cells are sensitive to the inhibition of the mevalonate pathway (MVP), which supports the biosynthesis of critical antioxidant intermediates and protect from ferroptosis. We attacked the susceptibility of PDA cells to ferroptotic death with selenorganic compounds, including dibenzyl diselenide (DBDS) that exhibits potent pro-oxidant properties and inhibits tumor growth in vitro and in vivo. DBDS treatment induces the mobilization of iron from mitochondria enabling uncontrolled lipid peroxidation. Finally, we showed that DBDS and statins act synergistically to promote ferroptosis and provide evidence that combined treatment is a viable strategy to combat PDA.

Cheminformatics-based discovery of new organoselenium compounds with potential for the treatment of cutaneous and visceral leishmaniasis

Leishmaniasis affects more than 12 million humans globally and a further 1 billion people are at risk in leishmaniasis endemic areas. The lack of a vaccine for leishmaniasis coupled with the limitations of existing anti-leishmanial therapies prompted this study. Cheminformatic techniques are widely used in screening large libraries of compounds, studying protein-ligand interactions, analysing pharmacokinetic properties, and designing new drug molecules with great speed, accuracy, and precision. This study was undertaken to evaluate the anti-leishmanial potential of some organoselenium compounds by quantitative structure-activity relationship (QSAR) modeling, molecular docking, pharmacokinetic analysis, and molecular dynamic (MD) simulation. The built QSAR model was validated (R2train = 0.8646, R2test = 0.8864, Q2 = 0.5773) and the predicted inhibitory activity (pIC50) values of the newly designed compounds were higher than that of the template (Compound 6). The new analogues (6a, 6b, and 6c) showed good binding interactions with the target protein (Pyridoxal kinase, PdxK) while also presenting excellent drug-likeness and pharmacokinetic profiles. The results of density functional theory, MD simulation, and molecular mechanics generalized Born surface area (MM/GBSA) analyses suggest the favourability and stability of protein-ligand interactions of the new analogues with PdxK, comparing favourably well with the reference drug (Pentamidine). Conclusively, the newly designed compounds could be synthesized and tested experimentally as potential anti-leishmanial drug molecules.Communicated by Ramaswamy H. Sarma.

Synthesis, cytotoxicity, antioxidant activity and molecular modeling of new NSAIDs-EBS derivatives

Two series of NSAIDs-EBS derivatives (5a-j and 9a-i) based on the hybridization of nonsteroidal anti-inflammatory drugs (NSAIDs) skeleton and Ebselen moiety were synthesized. Their cytotoxicity was evaluated against five types of human cancer cell lines, BGC-823 (human gastric cancer cell line), SW480 (human colon adenocarcinoma cells), MCF-7 (human breast adenocarcinoma cells), HeLa (human cervical cancer cells), A549 (human lung carcinoma cells). Moreover, the most active compound 5j showed IC50 values below 3 μM in all cancer cell lines and with remarkable anticancer activity against MCF-7 (1.5 μM) and HeLa (1.7 μM). The redox properties of the NSAIDs-EBS derivatives prepared herein were conducted by 2, 2-didiphenyl-1-picrylhydrazyl (DPPH), bleomycin dependent DNA damage and glutathione peroxidase (GPx)-like assays. Finally, TrxR1 inhibition activity assay and molecular docking study revealed NSAIDs-EBS derivatives could serve as potential TrxR1 inhibitor.

Organoselenium Compounds: Chemistry and Applications in Organic Synthesis

Selenium, originally described as a toxin, turns out to be a crucial trace element for life that appears as selenocysteine and its dimer, selenocystine. From the point of view of drug developments, selenium-containing drugs are isosteres of sulfur and oxygen 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. In this article, we have focused on the relevant features of the selenium atom, above all, the corresponding synthetic approaches to access a variety of organoselenium molecules along with the proposed reaction mechanisms. The preparation and biological properties of selenosugars, including selenoglycosides, selenonucleosides, selenopeptides, and other selenium-containing compounds will be treated. We have attempted to condense the most important aspects and interesting examples of the chemistry of selenium into a single article.

Antimicrobial and anti-viral effects of selenium nanoparticles and selenoprotein based strategies: COVID-19 and beyond

Deficiency of selenium (Se) has been described in a significant number of COVID-19 patients having a higher incidence of mortality, which makes it a pertinent issue to be addressed clinically for effective management of the COVID-19 pandemic. Se nanoparticles (SeNPs) provide a unique option for managing the havoc caused by the COVID-19 pandemic. SeNPs possess promising anti-inflammatory and anti-fibrotic effects by virtue of their nuclear factor kappa-light-chain-stimulator of activated B cells (NFκB), mitogen-activated protein kinase (MAPKs), and transforming growth factor-beta (TGF-β) modulatory activity. In addition, SeNPs possess remarkable immunomodulatory effects, making them a suitable option for supplementation with a much lower risk of toxicity compared to their elemental counterpart. Further, SeNPs have been shown to curtail viral and microbial infections, thus, making it a novel means to halt viral growth. In addition, it can be administered in the form of aerosol spray, direct injection, or infused thin-film transdermal patches to reduce the spread of this highly contagious viral infection. Moreover, a considerable decrease in the expression of selenoprotein along with enhanced expression of IL-6 in COVID-19 suggests a potential association among selenoprotein expression and COVID-19. In this review, we highlight the unique antimicrobial and antiviral properties of SeNPs and the immunomodulatory potential of selenoproteins. We provide the rationale behind their potentially interesting properties and further exploration in the context of microbial and viral infections. Further, the importance of selenoproteins and their role in maintaining a successful immune response along with their association to Se status is summarized.

First Generation of Antioxidant Precursors for Bioisosteric Se-NSAIDs: Design, Synthesis, and In Vitro and In Vivo Anticancer Evaluation

The introduction of selenium (Se) into organic scaffolds has been demonstrated to be a promising framework in the field of medicinal chemistry. A novel design of nonsteroidal anti-inflammatory drug (NSAID) derivatives based on a bioisosteric replacement via the incorporation of Se as diacyl diselenide is reported. The antioxidant activity was assessed using the DPPH radical scavenging assay. The new Se-NSAID derivatives bearing this unique combination showed antioxidant activity in a time- and dose-dependent manner, and also displayed different antiproliferative profiles in a panel of eight cancer cell lines as determined by the MTT assay. Ibuprofen derivative 5 was not only the most antioxidant agent, but also selectively induced toxicity in all the cancer cell lines tested (IC50 < 10 µM) while sparing nonmalignant cells, and induced apoptosis partially without enhancing the caspase 3/7 activity. Furthermore, NSAID derivative 5 significantly suppressed tumor growth in a subcutaneous colon cancer xenograft mouse model (10 mg/kg, TGI = 72%, and T/C = 38%) without exhibiting any apparent toxicity. To our knowledge, this work constitutes the first report on in vitro and in vivo anticancer activity of an unprecedented Se-NSAID hybrid derivative and its rational use for developing precursors for bioisosteric selenocompounds with appealing therapeutic applications.

Preparative Biocatalytic Synthesis of α-Ketomethylselenobutyrate-A Putative Agent for Cancer Therapy

Biomedical studies of the role of organic selenium compounds indicate that the amino acid derivative of L-selenomethionine, α-ketomethylselenobutyrate (KMSB), can be considered a potential anticancer therapeutic agent. It was noted that, in addition to a direct effect on redox signaling molecules, α-ketoacid metabolites of organoselenium compounds are able to change the status of histone acetylation and suppress the activity of histone deacetylases in cancer cells. However, the wide use of KMSB in biomedical research is hindered not only by its commercial unavailability, but also by the fact that there is no detailed information in the literature on possible methods for the synthesis of this compound. This paper describes in detail the procedure for obtaining a high-purity KMSB preparation (purity ≥ 99.3%) with a yield of the target product of more than 67%. L-amino acid oxidase obtained from C. adamanteus was used as a catalyst for the conversion of L-selenomethionine to KMSB. If necessary, this method can be used as a basis both for scaling up the synthesis of KMSB and for developing cost-effective biocatalytic technologies for obtaining other highly purified drugs.

Transferrin-Decorated PLGA Nanoparticles Loaded with an Organoselenium Compound as an Innovative Approach to Sensitize MDR Tumor Cells: An In Vitro Study Using 2D and 3D Cell Models

Multidrug resistance (MDR) is the main challenge in cancer treatment. In this sense, we designed transferrin (Tf)-conjugated PLGA nanoparticles (NPs) containing an organoselenium compound as an alternative to enhance the efficacy of cancer therapy and sensitize MDR tumor cells. Cytotoxicity studies were performed on different sensitive tumor cell lines and on an MDR tumor cell line, and the Tf-conjugated NPs presented significantly higher antiproliferative activity than the nontargeted counterparts in all tested cell lines. Due to the promising antitumor activity of the Tf-decorated NPs, further studies were performed using the MDR cells (NCI/ADR-RES cell line) comparatively to one sensitive cell line (HeLa). The cytotoxicity of NPs was evaluated in 3D tumor spheroids and, similarly to the results achieved in the 2D assays, the Tf-conjugated NPs were more effective at reducing the spheroid's growth. The targeted Tf-NPs were also able to inhibit tumor cell migration, presented a higher cell internalization and induced a greater number of apoptotic events in both cell lines. Therefore, these findings evidenced the advantages of Tf-decorated NPs over the nontargeted counterparts, with the Tf-conjugated NPs containing an organoselenium compound representing a promising drug delivery system to overcome MDR and enhance the efficacy of cancer therapy.

Preparation of Selenium-Based Drug-Modified Polymeric Ligand-Functionalised Fe3O4 Nanoparticles as Multimodal Drug Carrier and Magnetic Hyperthermia Inductor

In recent years, much effort has been invested into developing multifunctional drug delivery systems to overcome the drawbacks of conventional carriers. Magnetic nanoparticles are not generally used as carriers but can be functionalised with several different biomolecules and their size can be tailored to present a hyperthermia response, allowing for the design of multifunctional systems which can be active in therapies. In this work, we have designed a drug carrier nanosystem based on Fe₃O₄ nanoparticles with large heating power and 4-amino-2-pentylselenoquinazoline as an attached drug that exhibits oxidative properties and high selectivity against a variety of cancer malignant cells. For this propose, two samples composed of homogeneous Fe₃O₄ nanoparticles (NPs) with different sizes, shapes, and magnetic properties have been synthesised and characterised. The surface modification of the prepared Fe₃O₄ nanoparticles has been developed using copolymers composed of poly(ethylene-alt-maleic anhydride), dodecylamine, polyethylene glycol and the drug 4-amino-2-pentylselenoquinazoline. The obtained nanosystems were properly characterised. Their in vitro efficacy in colon cancer cells and as magnetic hyperthermia inductors was analysed, thereby leaving the door open for their potential application as multimodal agents.

The Role of Selenium and Manganese in the Formation, Diagnosis and Treatment of Cervical, Endometrial and Ovarian Cancer

Selenium (Se) and manganese (Mn) are essential micronutrients that are important elements of cell metabolism. They are involved in the composition of enzyme systems and regulate enzyme activity. Disturbances in the homeostasis of these micronutrients affect the development of many diseases and carcinogenesis, which can be linked to increased levels of oxidative stress and impaired antioxidant properties of many enzymes. Selenium has a very important function in maintaining immune-endocrine, metabolic and cellular homeostasis. Manganese, on the other hand, is important in development, digestion, reproduction, antioxidant defense, energy production, immune response and regulation of neuronal activity. We review the role of selenium and manganese and their effects on tumor growth, metastasis potential and remodeling of the microenvironment. We also describe their role as potential biomarkers in the diagnosis and the potential for the use of Se- and Mn-containing compounds in composition for the treatment of cancer of the reproductive organs.

Attenuation of doxorubicin-induced hypothalamic-pituitary-testicular axis dysfunction by diphenyl diselenide involves suppression of hormonal deficits, oxido-inflammatory stress and caspase 3 activity in rats

BACKGROUND

Doxorubicin (DOX) is one of the popular anti-cancer drugs in the world and several literatures have implicated it in various toxicities especially cardiotoxicity and reproductive toxicity. Diphenyl diselenide (DPDS) is well acknowledged for its compelling pharmacological effects in numerous disease models and chemically-mediated toxicity. This study was carried out to investigate the effect of DPDS on DOX-induced changes in the reproductive indices of male Wistar rats.

METHODS

Rats were intraperitoneally injected with 7.5 mg/kg body weight of DOX alone once followed by treatment with DPDS at 5 and 10 mg/kg for seven successive days. Excised hypothalamus, testes and epididymis were processed for biochemical and histological analyses.

RESULTS

DPDS treatment significantly (p < 0.05) abated DOX-induced oxidative damage by decreasing the levels of oxidative stress indices such as hydrogen peroxide, reactive oxygen and nitrogen species, and lipid peroxidation with a respective improvement in the level of glutathione in the hypothalamic, testicular and epididymal tissues of DOX-treated rats. The activities of antioxidant enzymes such as catalase, superoxide dismutase, glutathione S-transferase and glutathione peroxidase were upregulated in the DPDS co-treated group. DPDS co-treatment alleviates the burden of DOX-induced inflammation by significant reductions in myeloperoxidase activity, levels of nitric oxide and tumor necrosis factor alpha with concomitant decline in the activity of caspase-3, an apoptotic biomarker. Consequently, significant improvement in the spermiogram, levels of reproductive hormones (follicle stimulating hormone, luteinizing hormone, prolactin, serum testosterone and intra-testicular testosterone) levels in the DPDS co-treatment group in comparison to DOX alone-treated group were observed. Histology results of the testes and epididymis showed that DPDS significantly alleviated pathological lesions induced by DOX in the animals.

CONCLUSION

DPDS may modulate reproductive toxicity associated with DOX therapy in male cancer patients.

Novel Acylselenourea Derivatives: Dual Molecules with Anticancer and Radical Scavenging Activity

Oxidative stress surrounding cancer cells provides them with certain growth and survival advantages necessary for disease progression. In this context, Se-containing molecules have gained attention due to their anticancer and antioxidant activity. In our previous work, we synthesized a library of 39 selenoesters containing functional groups commonly present in natural products (NP), which showed potent anticancer activity, but did not demonstrate high radical scavenger activity. Thus, 20 novel Se derivatives resembling NP have been synthesized presenting acylselenourea functionality in their structures. Radical scavenger activity was tested using DPPH assay and in vitro protective effects against ROS-induced cell death caused by H₂O₂. Additionally, antiproliferative activity was evaluated in prostate, colon, lung, and breast cancer cell lines, along with their ability to induce apoptosis. Compounds 1.I and 5.I showed potent cytotoxicity against the tested cancer cell lines, along with high selectivity indexes and induction of caspase-mediated apoptosis. These compounds exhibited potent and concentration-dependent radical scavenging activity achieving DPPH inhibition similar to ascorbic acid and trolox. To conclude, we have demonstrated that the introduction of Se in the form of acylselenourea into small molecules provides strong radical scavengers in vitro and antiproliferative activity, which may lead to the development of promising dual compounds.

New Insights into Oxidative and Reductive Stress Responses and Their Relation to the Anticancer Activity of Selenium-Containing Compounds as Hydrogen Selenide Donors

Redox balance is important for the homeostasis of normal cells, but also for the proliferation, progression, and survival of cancer cells. Both oxidative and reductive stress can be harmful to cells. In contrast to oxidative stress, reductive stress and the therapeutic opportunities underlying the mechanisms of reductive stress in cancer, as well as how cancer cells respond to reductive stress, have received little attention and are not as well characterized. Therefore, there is recent interest in understanding how selective induction of reductive stress may influence therapeutic treatment and disease progression in cancer. There is also the question of how cancer cells respond to reductive stress. Selenium compounds have been shown to have chemotherapeutic effects against cancer, and their anticancer mechanism is thought to be related to the formation of their metabolites, including hydrogen selenide (H₂Se), which is a highly reactive and reducing molecule. Here, we highlight recent reports on the molecular mechanism of how cells recognize and respond to oxidative and reductive stress (1) and the mechanisms through which different types of selenium compounds can generate H₂Se (2) and thus selectively affect reductive stress under controlled conditions, which may be important for their anticancer effects.

The Phthalic Selenoanhydride Decreases Rat Blood Pressure and Tension of Isolated Mesenteric, Femoral and Renal Arteries

Phthalic selenoanhydride (R-Se) solved in physiological buffer releases various reactive selenium species including H₂Se. It is a potential compound for Se supplementation which exerts several biological effects, but its effect on the cardiovascular system is still unknown. Therefore, herein we aimed to study how R-Se affects rat hemodynamic parameters and vasoactive properties in isolated arteries. The right jugular vein of anesthetized Wistar male rats was cannulated for IV administration of R-Se. The arterial pulse waveform (APW) was detected by cannulation of the left carotid artery, enabling the evaluation of 35 parameters. R-Se (1-2 µmol kg^-1), but not phthalic anhydride or phthalic thioanhydride, transiently modulated most of the APW parameters including a decrease in systolic and diastolic blood pressure, heart rate, dP/dt_max relative level, or anacrotic/dicrotic notches, whereas systolic area, dP/dt_min delay, dP/dt_d delay, anacrotic notch relative level or its delay increased. R-Se (~10-100 µmol L^-1) significantly decreased the tension of precontracted mesenteric, femoral, and renal arteries, whereas it showed a moderate vasorelaxation effect on thoracic aorta isolated from normotensive Wistar rats. The results imply that R-Se acts on vascular smooth muscle cells, which might underlie the effects of R-Se on the rat hemodynamic parameters.

Selenylated Imidazo [1,2-a]pyridine Induces Apoptosis and Oxidative Stress in 2D and 3D Models of Colon Cancer Cells

Colon cancer incidence rates are increasing annually, a scenario aggravated by genetic and epigenetic alterations that promote drug resistance. Recent studies showed that novel synthetic selenium compounds are more efficient and less toxic than conventional drugs, demonstrating biocompatibility and pro-oxidant effects on tumor cells. This study aimed to investigate the cytotoxic effect of MRK-107, an imidazo [1,2- a]pyridine derivative, in 2D and 3D cell culture models of colon cancer (Caco-2 and HT-29). Sulforhodamine B results revealed a GI50 of 2.4 µM for Caco-2, 1.1 µM for HT-29, and 22.19 µM for NIH/3T3 in 2D cultures after 48 h of treatment. Cell recovery, migration, clonogenic, and Ki-67 results corroborated that MRK-107 inhibits cell proliferation and prevents cell regeneration and metastatic transition by selectively reducing migratory and clonogenic capacity; non-tumor cells (NIH/3T3) re-established proliferation in less than 18 h. The oxidative stress markers DCFH-DA and TBARS revealed increased ROS generation and oxidative damage. Caspases-3/7 are activated and induce apoptosis as the main mode of cell death in both cell models, as assessed by annexin V-FITC and acridine orange/ethidium bromide staining. MRK-107 is a selective, redox-active compound with pro-oxidant and pro-apoptotic properties and the capacity to activate antiproliferative pathways, showing promise in anticancer drug research.

Using chitosan-stabilized, hyaluronic acid-modified selenium nanoparticles to deliver CD44-targeted PLK1 siRNAs for treating bladder cancer

Aims: Achieving an effective biocompatible system for siRNAs delivery to the tumor site remains a significant challenge. Materials & methods: Selenium nanoparticles (SeNPs) modified by chitosan (CS) and hyaluronic acid (HA) were fabricated for PLK1 siRNAs (siPLK1) delivery to the bladder cancer cells. The HA-CS-SeNP@siPLK1 efficacy was evaluated using in vitro and in vivo models. Results: HA-CS-SeNP@siPLK1 was selectively internalized into T24 cells through clathrin-mediated endocytosis. Treatment with HA-CS-SeNP@siPLK1 successfully silenced the PLK1 gene, inhibited cell proliferation and induced cell cycle arrest in vitro. HA-CS-SeNP@siPLK1 could also inhibit tumor growth in vivo without causing systemic toxicity. Conclusion: Our results suggest that HA-CS-SeNPs may provide a good vehicle for delivering siPLK1 to the bladder tumor site.

Heparin Biofunctionalized Selenium Nanoparticles as Potential Antiangiogenic-Chemotherapeutic Agents for Targeted Doxorubicin Delivery

Combining antiangiogenic and chemotherapeutic agents has shown promising clinical benefits in cancer cures when the therapeutic intervention takes into account the tissue and molecular targets. Moreover, the risk of induced drug resistance is minimized when multiple pathways are involved in the treatment regimen, yielding a better therapeutic outcome. Nanodrug delivery systems have proven to be a prudent approach to treating complex disease pathologies. As such, combining antiangiogenic and chemotherapeutic drugs within multimodal nanocarriers synergistically augments the clinical efficiency of the drugs. This study reports the combinatorial efficacy of heparin (Hep), selenium NPs (SeNPs), and doxorubicin (Dox) to inhibit tumor growth and progression. Both Se@Hep-NPs and Se@Hep-Dox-NPs with excellent water dispersity having a size and charge in the range of 250 ± 5 and 253 ± 5 nm and -53 ± 0.4 and -48.4 ± 6.4 mV, respectively, showed strong anticancer potential assessed through in vitro assays like cell viability, specificity, colony formation, and wound scratch in MCF7 cells. Strong synergistic interactions among SeNPs, Hep, and Dox in Se@Hep-Dox-NPs render it to be an antiangiogenic and proapoptotic cancer cell death inducers. In vivo imaging highlights the dual-mode attributes of Se@Hep-NPs with desirable passive tumor targeting and biomedical imaging ability when tagged with Cy7.5, while Se@Hep-Dox-NPs significantly reduce the tumor burden and prolong the longevity of subcutaneous EAC-bearing mice. Histopathology studies reveal no signs of toxicity in major organs. Collectively, these results qualify Se@Hep-Dox-NPs as a plausible clinical therapeutic candidate.

Review on the health-promoting effect of adequate selenium status

Selenium is an essential microelement involved in various biological processes. Selenium deficiency increases the risk of human immunodeficiency virus infection, cancer, cardiovascular disease, and inflammatory bowel disease. Selenium possesses anti-oxidant, anti-cancer, immunomodulatory, hypoglycemic, and intestinal microbiota-regulating properties. The non-linear dose-response relationship between selenium status and health effects is U-shaped; individuals with low baseline selenium levels may benefit from supplementation, whereas those with acceptable or high selenium levels may face possible health hazards. Selenium supplementation is beneficial in various populations and conditions; however, given its small safety window, the safety of selenium supplementation is still a subject of debate. This review summarizes the current understanding of the health-promoting effects of selenium on the human body, the dietary reference intake, and evidence of the association between selenium deficiency and disease.

Reversal of Multidrug Resistance by Symmetrical Selenoesters in Colon Adenocarcinoma Cells

Recently, selenium containing derivatives have attracted more attention in medicinal chemistry. In the present work, the anticancer activity of symmetrical selenoesters was investigated by studying the reversal of efflux pump-related and apoptosis resistance in sensitive and resistant human colon adenocarcinoma cells expressing the ABCB1 protein. The combined effect of the compounds with doxorubicin was demonstrated with a checkerboard assay. The ABCB1 inhibitory and the apoptosis-inducing effects of the derivatives were measured with flow cytometry. Whole transcriptome sequencing was carried out on Illumina platform upon the treatment of resistant cells with the most potent derivatives. One ketone and three methyl ester selenoesters showed synergistic or weak synergistic interaction with doxorubicin, respectively. Ketone selenoesters were the most potent ABCB1 inhibitors and apoptosis inducers. Nitrile selenoesters could induce moderate early and late apoptotic processes that could be explained by their ABCB1 modulating properties. The transcriptome analysis revealed that symmetrical selenoesters may influence the redox state of the cells and interfere with metastasis formation. It can be assumed that these symmetrical selenocompounds possess toxic, DNA-damaging effects due to the presence of two selenium atoms in the molecule, which may be augmented by the presence of symmetrical groups.

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.

Design, Synthesis and Antitumor Activity of Novel Selenium-Containing Tepotinib Derivatives as Dual Inhibitors of c-Met and TrxR

Cellular mesenchymal-epithelial transition factor (c-Met), an oncogenic transmembrane receptor tyrosine kinase (RTK), plays an essential role in cell proliferation during embryo development and liver regeneration. Thioredoxin reductase (TrxR) is overexpressed and constitutively active in most tumors closely related to cancer recurrence. Multi-target-directed ligands (MTDLs) strategy provides a logical approach to drug combinations and would adequately address the pathological complexity of cancer. In this work, we designed and synthesized a series of selenium-containing tepotinib derivatives by means of selenium-based bioisosteric modifications and evaluated their antiproliferative activity. Most of these selenium-containing hybrids exhibited potent dual inhibitory activity toward c-Met and TrxR. Among them, compound 8b was the most active, with an IC₅₀ value of 10 nM against MHCC97H cells. Studies on the mechanism of action revealed that compound 8b triggered cell cycle arrest at the G₁ phase and caused ROS accumulations by targeting TrxR, and these effects eventually led to cell apoptosis. These findings strongly suggest that compound 8b serves as a dual inhibitor of c-Met and TrxR, warranting further exploitation for cancer therapy.

Biogenic Selenium Nanoparticles in Biomedical Sciences: Properties, Current Trends, Novel Opportunities and Emerging Challenges in Theranostic Nanomedicine

Selenium is an important dietary supplement and an essential trace element incorporated into selenoproteins with growth-modulating properties and cytotoxic mechanisms of action. However, different compounds of selenium usually possess a narrow nutritional or therapeutic window with a low degree of absorption and delicate safety margins, depending on the dose and the chemical form in which they are provided to the organism. Hence, selenium nanoparticles (SeNPs) are emerging as a novel therapeutic and diagnostic platform with decreased toxicity and the capacity to enhance the biological properties of Se-based compounds. Consistent with the exciting possibilities offered by nanotechnology in the diagnosis, treatment, and prevention of diseases, SeNPs are useful tools in current biomedical research with exceptional benefits as potential therapeutics, with enhanced bioavailability, improved targeting, and effectiveness against oxidative stress and inflammation-mediated disorders. In view of the need for developing eco-friendly, inexpensive, simple, and high-throughput biomedical agents that can also ally with theranostic purposes and exhibit negligible side effects, biogenic SeNPs are receiving special attention. The present manuscript aims to be a reference in its kind by providing the readership with a thorough and comprehensive review that emphasizes the current, yet expanding, possibilities offered by biogenic SeNPs in the biomedical field and the promise they hold among selenium-derived products to, eventually, elicit future developments. First, the present review recalls the physiological importance of selenium as an oligo-element and introduces the unique biological, physicochemical, optoelectronic, and catalytic properties of Se nanomaterials. Then, it addresses the significance of nanosizing on pharmacological activity (pharmacokinetics and pharmacodynamics) and cellular interactions of SeNPs. Importantly, it discusses in detail the role of biosynthesized SeNPs as innovative theranostic agents for personalized nanomedicine-based therapies. Finally, this review explores the role of biogenic SeNPs in the ongoing context of the SARS-CoV-2 pandemic and presents key prospects in translational nanomedicine.

Selenium speciation-dependent cancer radiosensitization by induction of G2/M cell cycle arrest and apoptosis

Introduction: Radiation therapy has Q6long been a routine and effective treatment for non-small cell lung cancer (NSCLC), but the radioresistance and side effects have limited its application. In recent years, the superiority showed by trace element selenium in tumor radiotherapy sensitization has received wide attention. However, different forms of selenium compounds exhibit different chemical properties and their mechanisms of action on tumors may be different. Methods: Human non-small cell lung cancer SPC-A1 cells were studied. Drug toxicity was detected by MTT assay. The selenium content absorbed in vitro at different time points was detected by ICP-MS. Colony formation were conducted to observe the radiosensitization effect of different selenium compounds on SPC-A1 cells, and to compare the proliferation ability of SPC-A1 cells treated by radiation alone and radiation combined with different selenium compounds. Cell migration was detected by cell scratch assay. The changes of cell cycle and apoptosis were detected by flow cytometry. DCFH-DA fluorescent probe was used to detect the effects of different selenium compounds combined with X-ray on ROS production. Results: In this study, these four representative selenium compounds all have a certain ability to enhance the ability of radiotherapy to inhibit tumor cell proliferation and migration, and the mechanism may be related to blocking cell cycle in G2/M phase, activating the caspase cascade and reducing intracellular ROS levels to induce tumor cell apoptosis. Among them, -2-valent organic selenium has the most obvious effect, mainly inhibits cell migration, and induces early apoptosis by activating a large number of caspase-3, and arrest the cell cycle in S phase and G2/M phase. 0-valent selenium nanoparticles mainly arrest the cell cycle in G2/M phase. +4-valent inorganic selenium exerts its antitumor effects primarily by inhibiting tumor cell migration and inducing early apoptosis of tumor cells. Discussion: In this paper, the antitumor effects of four different forms of selenium compounds combined with X-rays on SPC-A1 cells were investigated, and their inhibitory effects on the proliferation and migration of cancer cells and their mechanisms were examined. We found that the radiosensitizing effect of selenium on NSCLC was closely related to its selenium form through the study of the sensitizing effect of different kinds of selenium compounds on radiotherapy.