Selenized Plant Oil Is an Efficient Source of Selenium for Selenoprotein Biosynthesis in Human Cell Lines

Selenium Modification of Natural Products and Its Research Progress

The selenization of natural products refers to the chemical modification method of artificially introducing selenium atoms into natural products to interact with the functional groups in the target molecule to form selenides. Nowadays, even though scientists in fields involving organic selenium compounds have achieved numerous results due to their continuous investment, few comprehensive and systematic summaries relating to their research results can be found. The present paper summarizes the selenization modification methods of several kinds of important natural products, such as polysaccharides, proteins/polypeptides, polyphenols, lipids, and cyclic compounds, as well as the basic principles or mechanisms of the selenizing methods. On this basis, this paper explored the future development trend of the research field relating to selenized natural products, and it is hoped to provide some suggestions for directional selenization modification and the application of natural active ingredients.

Interplay between Selenium, Selenoproteins and HIV-1 Replication in Human CD4 T-Lymphocytes

The infection of CD4 T-lymphocytes with human immunodeficiency virus (HIV), the etiological agent of acquired immunodeficiency syndrome (AIDS), disrupts cellular homeostasis, increases oxidative stress and interferes with micronutrient metabolism. Viral replication simultaneously increases the demand for micronutrients and causes their loss, as for selenium (Se). In HIV-infected patients, selenium deficiency was associated with a lower CD4 T-cell count and a shorter life expectancy. Selenium has an important role in antioxidant defense, redox signaling and redox homeostasis, and most of these biological activities are mediated by its incorporation in an essential family of redox enzymes, namely the selenoproteins. Here, we have investigated how selenium and selenoproteins interplay with HIV infection in different cellular models of human CD4 T lymphocytes derived from established cell lines (Jurkat and SupT1) and isolated primary CD4 T cells. First, we characterized the expression of the selenoproteome in various human T-cell models and found it tightly regulated by the selenium level of the culture media, which was in agreement with reports from non-immune cells. Then, we showed that selenium had no significant effect on HIV-1 protein production nor on infectivity, but slightly reduced the percentage of infected cells in a Jurkat cell line and isolated primary CD4 T cells. Finally, in response to HIV-1 infection, the selenoproteome was slightly altered.

Selenoproteome Expression Studied by Non-Radioactive Isotopic Selenium-Labeling in Human Cell Lines

Selenoproteins, in which the selenium atom is present in the rare amino acid selenocysteine, are vital components of cell homeostasis, antioxidant defense, and cell signaling in mammals. The expression of the selenoproteome, composed of 25 selenoprotein genes, is strongly controlled by the selenium status of the body, which is a corollary of selenium availability in the food diet. Here, we present an alternative strategy for the use of the radioactive ⁷⁵Se isotope in order to characterize the selenoproteome regulation based on (i) the selective labeling of the cellular selenocompounds with non-radioactive selenium isotopes (⁷⁶Se, ⁷⁷Se) and (ii) the detection of the isotopic enrichment of the selenoproteins using size-exclusion chromatography followed by inductively coupled plasma mass spectrometry detection. The reliability of our strategy is further confirmed by western blots with distinct selenoprotein-specific antibodies. Using our strategy, we characterized the hierarchy of the selenoproteome regulation in dose–response and kinetic experiments.

Dietary Selenium Regulates microRNAs in Metabolic Disease: Recent Progress

Selenium (Se) is an essential element for the maintenance of a healthy physiological state. However, due to environmental and dietary factors and the narrow safety range of Se, diseases caused by Se deficiency or excess have gained considerable traction in recent years. In particular, links have been identified between low Se status, cognitive decline, immune disorders, and increased mortality, whereas excess Se increases metabolic risk. Considerable evidence has suggested microRNAs (miRNAs) regulate interactions between the environment (including the diet) and genes, and play important roles in several diseases, including cancer. MiRNAs target messenger RNAs to induce changes in proteins including selenoprotein expression, ultimately generating disease. While a plethora of data exists on the epigenetic regulation of other dietary factors, nutrient Se epigenetics and especially miRNA regulated mechanisms remain unclear. Thus, this review mainly focuses on Se metabolism, pathogenic mechanisms, and miRNAs as key regulatory factors in Se-related diseases. Finally, we attempt to clarify the regulatory mechanisms underpinning Se, miRNAs, selenoproteins, and Se-related diseases.

Selenium Compounds as Novel Potential Anticancer Agents

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

Scientific opinion on the safety of selenite triglycerides as a source of selenium added for nutritional purposes to food supplements

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on selenite triglycerides as a novel food (NF) pursuant to Regulation (EU) 2015/2283, their safety when added for nutritional purposes to food supplements as a source of selenium and the bioavailability of selenium from this source, in the context of Directive 2002/46/EC. The proposed NF is the first lipophilic organic form of selenium so far described in the literature. It is composed by a mixture of individual Se-containing lipids which do not occur in nature. The Panel considers that the information provided on the composition of the NF does not allow a complete characterisation of the product. From the data provided to characterise the absorption, distribution, metabolism and excretion of the NF, it cannot be established in which chemical form Se is systemically available and if it can enter the functional Se body pool to fulfil Se physiological functions. The Panel considers that, since it is not demonstrated that the NF is converted to a known form of Se following ingestion and absorption, the NF is to be treated as a xenobiotic with unknown properties in the body. From a subchronic toxicity study in rats, the Panel derives a lowest observed adverse effect level (LOAEL) for general toxicity of 2 mg Se/kg body weight (bw) per day based on findings indicating liver as a target organ, as it has been shown for other studies on dietary Se. The Panel concludes that the NF is absorbed and provides Se, but in an unknown form of which the bioavailability has not been determined. The Panel also concludes that the safety of the NF under the intended conditions of use cannot be established.