Dr Muhammad Torequl Islam :
Selenium (Se) is similar to sulfur (S), but its concentration in Earth crust is much lower and its distribution is very uneven. In nature Se exists mostly in two forms (e.g., tetravalent (Se4+) and selenates with hexavalent (Se6+) cations). Se is found as organic forms in plants, fruits, seeds and particularly in the nuts as a form of selenides, such as selenocysteine and selenomethionine. The selenoproteome contains 25 members in humans that exhibit a wide variety of functions. Generally, viral infection increases the demand for micronutrients and causes their loss, that can be compensated by micronutrient supplementation. Among the nutrients implicated in viral infection, Se has an important role in antioxidant defense, redox signaling and redox homeostasis.
Se incorporates as a rare amino acid selenocysteine (a selenoprotein) in its most biological activities. Selenocysteine is cotranslationally inserted into nascent polypeptide chains in response to the UGA codon, results in the termination of protein translation. Se deficiency is the main regulator of selenoprotein expression, which is associated with the pathogenicity of several viruses. Several selenoprotein members (e.g., glutathione peroxidases and thioredoxin reductases) have been also identifed as important antioxidant defense systems in different models of viral replication.
It is known that low serum Se is associated with increased incidence of cancer, heart diseases, neuromuscular disorders, male infertility, inflammation and numerous other disorders. Research evidence suggests that Se is essential for the mammalian development, immune function, inhibition of viral expression, and delaying the progression of human immunodeficiency virus infection and acquired immune deficiency syndrome. Se can oxidize the protein sulfhydryl groups (-SH) to inactive disulfides bonds (S-S). In this way the viral hydrophobic spike loses its ability to undergo the exchange reaction with disulfide groups of cell membrane proteins and prevents virus entering to the healthy cell cytoplasm. Se supplementation has been evident to inhibit the development of polio and influenza viruses. Se increases the proliferation of natural killer (NK) cells and it has a positive effect in combination with some vitamins (e.g., Vit D and E). Phytoncides found in onions (Allium cepa) along with Se increased T lymphocyte proliferation. Moreover, Se reduces the formation of thrombosis in the blood vessels.
COVID-19 results the formation of micro-clots, which is one of the significant causes of death in patients. Sodium selenite, but not selenate, can oxidize thiol groups in the virus protein disulfide isomerase rendering it unable to penetrate the healthy cell membrane. Moreover, sodium selenite may reduce the risk of blood clots forming (formation of high-molecular polymer – parafibrin) in patients with COVID-19. The RDA (Recommended Dietary Allowances) of Se in 14->51 yrs human (both male amd female) is 55 µg. RDA for birth to 13 yrs human is 15-40 µg. RDAs of Se for pegnant and lactating women are 60 and 70 µg, respectively. Our daily intake of Se varies greatly, from 50 to 600 µg/day. The median lethal dose (LD50) dose for the sodium selenite in rats was 4100 µg/kg body weight. Recent evidence indicates that Se concentration in human serum ranges from 400 to 30000 µg/L, the levels >1400 µg/L being non-toxic. It is generally believed that the toxic doses of selenite start from 600 µg/day. However, we can ingest 10000 µg of sodium selenite in one dose. Furthermore, it is inexpensive and readily available. Unfortunately, we have limited knowledge of this mineral, even we cannot understand that such a simple chemical substance may have dramatic health effects.
Selenium (Se) is similar to sulfur (S), but its concentration in Earth crust is much lower and its distribution is very uneven. In nature Se exists mostly in two forms (e.g., tetravalent (Se4+) and selenates with hexavalent (Se6+) cations). Se is found as organic forms in plants, fruits, seeds and particularly in the nuts as a form of selenides, such as selenocysteine and selenomethionine. The selenoproteome contains 25 members in humans that exhibit a wide variety of functions. Generally, viral infection increases the demand for micronutrients and causes their loss, that can be compensated by micronutrient supplementation. Among the nutrients implicated in viral infection, Se has an important role in antioxidant defense, redox signaling and redox homeostasis.
Se incorporates as a rare amino acid selenocysteine (a selenoprotein) in its most biological activities. Selenocysteine is cotranslationally inserted into nascent polypeptide chains in response to the UGA codon, results in the termination of protein translation. Se deficiency is the main regulator of selenoprotein expression, which is associated with the pathogenicity of several viruses. Several selenoprotein members (e.g., glutathione peroxidases and thioredoxin reductases) have been also identifed as important antioxidant defense systems in different models of viral replication.
It is known that low serum Se is associated with increased incidence of cancer, heart diseases, neuromuscular disorders, male infertility, inflammation and numerous other disorders. Research evidence suggests that Se is essential for the mammalian development, immune function, inhibition of viral expression, and delaying the progression of human immunodeficiency virus infection and acquired immune deficiency syndrome. Se can oxidize the protein sulfhydryl groups (-SH) to inactive disulfides bonds (S-S). In this way the viral hydrophobic spike loses its ability to undergo the exchange reaction with disulfide groups of cell membrane proteins and prevents virus entering to the healthy cell cytoplasm. Se supplementation has been evident to inhibit the development of polio and influenza viruses. Se increases the proliferation of natural killer (NK) cells and it has a positive effect in combination with some vitamins (e.g., Vit D and E). Phytoncides found in onions (Allium cepa) along with Se increased T lymphocyte proliferation. Moreover, Se reduces the formation of thrombosis in the blood vessels.
COVID-19 results the formation of micro-clots, which is one of the significant causes of death in patients. Sodium selenite, but not selenate, can oxidize thiol groups in the virus protein disulfide isomerase rendering it unable to penetrate the healthy cell membrane. Moreover, sodium selenite may reduce the risk of blood clots forming (formation of high-molecular polymer – parafibrin) in patients with COVID-19. The RDA (Recommended Dietary Allowances) of Se in 14->51 yrs human (both male amd female) is 55 µg. RDA for birth to 13 yrs human is 15-40 µg. RDAs of Se for pegnant and lactating women are 60 and 70 µg, respectively. Our daily intake of Se varies greatly, from 50 to 600 µg/day. The median lethal dose (LD50) dose for the sodium selenite in rats was 4100 µg/kg body weight. Recent evidence indicates that Se concentration in human serum ranges from 400 to 30000 µg/L, the levels >1400 µg/L being non-toxic. It is generally believed that the toxic doses of selenite start from 600 µg/day. However, we can ingest 10000 µg of sodium selenite in one dose. Furthermore, it is inexpensive and readily available. Unfortunately, we have limited knowledge of this mineral, even we cannot understand that such a simple chemical substance may have dramatic health effects.
(Dr. Muhammad Torequl Islam is Assistant Professor, Department of Pharmacy, Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj. E-mail: [email protected])
