Induction of lung glutathione and glutamylcysteine ligase by 1,4-phenylenebis(methylene)selenocyanate and its glutathione conjugate: role of nuclear factor-erythroid 2-related factor 2

Selective Impact of Selenium Compounds on Two Cytokine Storm Players

COVID-19 patients suffer from the detrimental effects of cytokine storm and not much success has been achieved to overcome this issue. We sought to test the ability of selenium to reduce the impact of two important cytokine storm players: IL-6 and TNF-α. The effects of four selenium compounds on the secretion of these cytokines from THP-1 macrophages were evaluated in vitro following an LPS challenge. Also, the potential impact of methylseleninic acid (MSeA) on Nrf2 and IκBα was determined after a short treatment of THP-1 macrophages. MSeA was found to be the most potent selenium form among the four selenium compounds tested that reduced the levels of IL-6 and TNF-α secreted by THP-1 macrophages. In addition, an increase in Nrf2 and decrease in pIκBα in human macrophages was observed following MSeA treatment. Our data indicate that COVID-19 patients might benefit from the addition of MSeA to the standard therapy due to its ability to suppress the key players in the cytokine storm.

Dietary Puerarin Supplementation Alleviates Oxidative Stress in the Small Intestines of Diquat-Challenged Piglets

Simple Summary

The oxidant stress which piglets suffer from during the weaning period has caused huge losses to the pig farm industry. It is important for scientists to find an effective way to alleviate the oxidant stress in weaned piglets. This study was designed to test the hypothesis that dietary puerarin supplementation alleviates oxidative stress in the small intestine of diquat-challenged piglets. Interestingly, dietary puerarin supplementation improved intestinal morphology, cell proliferation, barrier function, and increased Nrf2 and its downstream enzymes in diquat-challenged piglets, which shows that puerarin has potent protective effects against diquat-induced oxidative stress. These findings will be very beneficial to the pig industry, especially to the development of antibiotic-free diets, new anti-inflammatory drugs and the application of puerarin in piglets.

Abstract

This study was conducted to demonstrate that dietary puerarin supplementation alleviates oxidative stress in the small intestine of diquat-challenged piglets. The results showed that puerarin administration markedly alleviated diquat-induced intestinal injury, which was indicated by the improvement of intestinal morphology, cell proliferation and barrier function. One of the potential mechanisms responsible for this was the decrease in oxidative stress, as evidenced by the increase in activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC) in the small intestine. Puerarin increased the protein expression levels of NF-E2-related factor 2 (Nrf2) and its downstream enzymes, including heme oxygenase 1 (HO-1), glutamate–cysteine ligase catalytic and its modifier subunit (GCLc and GCLm) in the jejunal mucosa of diquat-induced piglets. Puerarin administration improved intestinal morphology, cell proliferation, and barrier function, and increased Nrf2 and its downstream enzymes. These findings indicate that the dietary supplementation of puerarin attenuates the oxidative stress involving Nrf2 signaling pathways in diquat-challenged piglets.

Development and Therapeutic Potential of Selenazo Compounds

Incorporation of selenium (Se) atom into small molecules can substantially enhance their antioxidant, anti-inflammatory, antimutagenic, antitumoral or chemopreventive, antiviral, antibacterial, antifungal, antiparasitic, and neuroprotective effects. Specifically, selenazo compounds have received great attention owing to their chemical properties, pharmaceutical applications, and low toxicity. In this Perspective, we compile extensive literature evidence with the description and discussion of the most recent advances in different selenazo and selenadiazo motifs as potential pharmacological candidates. We also provide some perspectives on the challenges and future directions in the advancement of these selenazo compounds, each of which could generate drug candidates for various diseases.

Selenides and Diselenides: A Review of Their Anticancer and Chemopreventive Activity

Selenium and selenocompounds have attracted the attention and the efforts of scientists worldwide due to their promising potential applications in cancer prevention and/or treatment. Different organic selenocompounds, with diverse functional groups that contain selenium, have been reported to exhibit anticancer and/or chemopreventive activity. Among them, selenocyanates, selenoureas, selenoesters, selenium-containing heterocycles, selenium nanoparticles, selenides and diselenides have been considered in the search for efficiency in prevention and treatment of cancer and other related diseases. In this review, we focus our attention on the potential applications of selenides and diselenides in cancer prevention and treatment that have been reported so far. The around 80 selenides and diselenides selected herein as representative compounds include promising antioxidant, prooxidant, redox-modulating, chemopreventive, anticancer, cytotoxic and radioprotective compounds, among other activities. The aim of this work is to highlight the possibilities that these novel organic selenocompounds can offer in an effort to contribute to inspire medicinal chemists in their search of new promising derivatives.

In vitro radical scavenging and cytotoxic activities of novel hybrid selenocarbamates

Novel selenocyanate and diselenide derivatives containing a carbamate moiety were synthesised and evaluated in vitro to determine their cytotoxic and radical scavenging properties. Cytotoxic activity was tested against a panel of human cell lines including CCRF-CEM (lymphoblastic leukaemia), HT-29 (colon carcinoma), HTB-54 (lung carcinoma), PC-3 (prostate carcinoma), MCF-7 (breast adenocarcinoma), 184B5 (non-malignant, mammary gland derived) and BEAS-2B (non-malignant, derived from bronchial epithelium). Most of the compounds displayed high antiproliferative activity with GI50 values below 10μM in MCF-7, CCRF-CEM and PC-3 cells. Radical scavenging properties of the new selenocompounds were confirmed testing their ability to scavenge DPPH and ABTS radicals. Based on the activity of selenium-based glutathione peroxidases (GPxs), compounds 1a, 2e and 2h were further screened for their capacity to reduce hydrogen peroxide under thiol presence. Results suggest that compound 1a mimics GPxs activity. Cytotoxic parameters, radical scavenging activity and ADME profile point to 1a as promising drug candidate.

Puerarin induces the upregulation of glutathione levels and nuclear translocation of Nrf2 through PI3K/Akt/GSK-3β signaling events in PC12 cells exposed to lead

Oxidative stress is thought to be involved in lead-induced toxicity, especially affecting the brain. We reported previously that puerarin possesses antioxidative properties in the nervous system. Therefore, the aim of the present study was to test the hypothesis that puerarin inhibits lead acetate-induced oxidative stress in PC12 cells by interrupting phosphatidylinositol-3 kinase (PI3K)/Akt signaling through increasing glutathione (GSH) synthesis. Our results showed that puerarin attenuates oxidative stress in a concentration-dependent manner in PC12 cells exposed to lead acetate demonstrated by scavenging reactive oxygen species (ROS) and reducing lipid peroxidation (LPO). Treatment with puerarin significantly up-regulates glutamate cysteine ligase catalytic subunit (GCLc) expression both at its mRNA and protein levels, but not glutamate cysteine ligase modifier (GCLm) subunit, accompanying the elevation of cellular glutathione level. The increased nuclear accumulation of nuclear factor erythroid 2-related factor 2 (Nrf2) was not because of increased transcription of Nrf2 as Nrf2 transcript levels did not change after puerarin treatment. The effects of puerarin could be partially blocked by pharmacologic inhibition of PI3K and the glycogen synthase kinase 3β (GSK-3β) pathways with LY294002 and LiCl, respectively. On the other hand, puerarin treatment promoted Akt and GSK-3β phosphorylation in PC12 cells exposed to lead acetate. Moreover, puerarin failed to modulate the phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2), p-c-Jun N-terminal kinases (JNK), and p-p38 mitogen-activated protein kinase (MAPK) demonstrating some specificity for its action on the PI3K/GSK-3β pathway. These findings suggest that puerarin as a phytoestrogen might be an attractive agent for prevention and treatment of chronic diseases related to lead neurotoxicity.

Upregulation of capacity for glutathione synthesis in response to amino acid deprivation: regulation of glutamate-cysteine ligase subunits

Using HepG2/C3A cells and MEFs, we investigated whether induction of GSH synthesis in response to sulfur amino acid deficiency is mediated by the decrease in cysteine levels or whether it requires a decrease in GSH levels per se. Both the glutamate-cysteine ligase catalytic (GCLC) and modifier (GCLM) subunit mRNA levels were upregulated in response to a lack of cysteine or other essential amino acids, independent of GSH levels. This upregulation did not occur in MEFs lacking GCN2 (general control non-derepressible 2, also known as eIF2α kinase 4) or in cells expressing mutant eIF2α lacking the eIF2α kinase Ser(51) phosphorylation site, indicating that expression of both GCLC and GCLM was mediated by the GCN2/ATF4 stress response pathway. Only the increase in GCLM mRNA level, however, was accompanied by a parallel increase in protein expression, suggesting that the enhanced capacity for GSH synthesis depended largely on increased association of GCLC with its regulatory subunit. Upregulation of both GCLC and GLCM mRNA levels in response to cysteine deprivation was dependent on new protein synthesis, which is consistent with expression of GCLC and GCLM being mediated by proteins whose synthesis depends on activation of the GCN2/ATF4 pathway. Our data suggest that the regulation of GCLC expression may be mediated by changes in the abundance of transcriptional regulators, whereas the regulation of GCLM expression may be mediated by changes in the abundance of mRNA stabilizing or destabilizing proteins. Upregulation of GCLM levels in response to low cysteine levels may serve to protect the cell in the face of a future stress requiring GSH as an antioxidant or conjugating/detoxifying agent.