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Selenium is an essential trace element in living organisms, and is present in selenoenzymes with antioxidant activity, like glutathione peroxidase (GPx) and thioredoxin reductase (TrxR). The search for small selenium-containing molecules that mimic selenoenzymes is a strong field of research in organic and medicinal chemistry. In this review, we review the synthesis and bioassays of new and known organoselenium compounds with antioxidant activity, covering the last five years. A detailed description of the synthetic procedures and the performed in vitro and in vivo bioassays is presented, highlighting the most active compounds in each series.

Myeloperoxidase (MPO) is a neutrophil-derived enzyme that has been recently associated with tumour development. However, the mechanisms by which this enzyme exerts its functions remain unclear. In this study, we investigated whether myeloperoxidase can alter the function of A549 human lung cancer cells. We observed that MPO promoted the proliferation of cancer cells and inhibited their apoptosis. Additionally, it increased the phosphorylation of AKT and ERK. MPO was rapidly bound to and internalized by A549 cells, retaining its enzymatic activity. Furthermore, MPO partially translocated into the nucleus and was detected in the chromatin-enriched fraction. Effects of MPO on cancer cell function could be reduced when MPO uptake was blocked with heparin or upon inhibition of the enzymatic activity with the MPO inhibitor 4-aminobenzoic acid hydrazide (4-ABAH). Lastly, we have shown that tumour-bearing mice treated with 4-ABAH had reduced tumour burden when compared to control mice. Our results highlight the role of MPO as a neutrophil-derived enzyme that can alter the function of lung cancer cells.

Cutibacterium acnes is one of the most abundant bacteria on the skin. Being exposed to oxygen and oxic stress, the secretion of the bacterial antioxidant protein RoxP ensures an endogenous antioxidant system for the preservation of skin health. To investigate the impact of the antioxidant RoxP on oxidation of the bacteria, wildtype and an isogenic roxp mutant were cultured in anaerobic and oxic conditions. The carbonylated status of proteins were recorded, as were the most significant modifications in a relative intensity of free fatty acids (FFA) and lipids containing fatty acids (FA), such as di- (DG) and triglycerides (TG), di- (DGDG) and sulfoquinozyldiacylglycerol (SQDG) and ceramides. Concerning the fatty acid types, it was observed that the free fatty acids contained mainly C12:0–C26:0 in hydroxy and acylated forms, the DG contained mainly C29:0–C37:0, the TG contained mainly C19:0–C33:0, and the DGDG/SQDGs contained very long fatty acids (C29:0–C37:0) demonstrating the interdependence of de novo synthesis of lipids and RoxP. The area of DGDG peaks (924.52, 929.56 and 930.58) were affected by bacterial growth conditions, with the exception of m/z 910.61. Moreover, the FFA unsaturation is wider in the SQDG species (C30:0 to C36:6) than in DG, TG or free FFA species. It could be concluded that both environmental oxidative statuses, as well as the prevalence of bacterial antioxidant systems, significantly shape the lipidome of C. acnes.

Aims Sotagliflozin (SOTA) as adjunct to insulin therapy improves glycemic control, reduces body weight and blood pressure, and increases time in range in adults with type 1 diabetes (T1D). SOTA demonstrated CV and kidney benefits in high-risk adults with type 2 diabetes. These potential benefits using SOTA for T1D may collectively outweigh the risk of diabetic ketoacidosis. The present analysis estimated the risk of CVD and kidney failure in adults with T1D treated with SOTA. Materials and Methods Participant-level data were used from the inTandem trials evaluating 2980 adults with T1D randomized to once-daily placebo, SOTA 200 mg, or SOTA 400 mg for 24 weeks. For each participant, the cumulative risks of developing CVD and kidney failure were estimated using the Steno T1 Risk Engine. A subgroup analysis was performed in participants with BMI ≥ 27 kg/m2. Results SOTA significantly reduced the predicted 5- and 10-year CVD risk in the SOTA 200 and 400 mg pooled group with a relative change in the SOTA group compared to the relative change in the placebo group of (mean [95%-confidence interval (CI)]) −6.6 (−7.9, −5.3) % and −6.4 (−7.6, −5.1) % (p < 0.0001 for both) respectively. For the 5-year ESKD risk there was a significant reduction with a relative change of −5.0 (−7.6, −2.3) % (p = 0.0003). Similar results were observed with the individual doses and in participants with BMI ≥ 27 kg/m2. Conclusion This analysis provides additional clinical results that may positively balance the benefit/risk assessment of SGLT inhibition use in T1D., Aims Sotagliflozin (SOTA) as adjunct to insulin therapy improves glycemic control, reduces body weight and blood pressure, and increases time in range in adults with type 1 diabetes (T1D). SOTA demonstrated CV and kidney benefits in high-risk adults with type 2 diabetes. These potential benefits using SOTA for T1D may collectively outweigh the risk of diabetic ketoacidosis. The present analysis estimated the risk of CVD and kidney failure in adults with T1D treated with SOTA.Materials and Methods Participant-level data were used from the inTandem trials evaluating 2980 adults with T1D randomized to once-daily placebo, SOTA 200 mg, or SOTA 400 mg for 24 weeks. For each participant, the cumulative risks of developing CVD and kidney failure were estimated using the Steno T1 Risk Engine. A subgroup analysis was performed in participants with BMI =27 kg/m(2).Results SOTA significantly reduced the predicted 5- and 10-year CVD risk in the SOTA 200 and 400 mg pooled group with a relative change in the SOTA group compared to the relative change in the placebo group of (mean [95%-confidence interval (CI)]) -6.6 (-7.9, -5.3) % and -6.4 (-7.6, -5.1) % (p < 0.0001 for both) respectively. For the 5-year ESKD risk there was a significant reduction with a relative change of -5.0 (-7.6, -2.3) % (p = 0.0003). Similar results were observed with the individual doses and in participants with BMI =27 kg/m(2).Conclusion This analysis provides additional clinical results that may positively balance the benefit/risk assessment of SGLT inhibition use in T1D.

Glutamine synthetase (GS), which catalyzes the ATP-dependent synthesis of L-glutamine from L-glutamate and ammonia, is a ubiquitous and conserved enzyme that plays a pivotal role in nitrogen metabolism across all life domains. In vertebrates, GS is highly expressed in astrocytes, where its activity sustains the glutamate-glutamine cycle at glutamatergic synapses and is thus essential for maintaining brain homeostasis. In fact, decreased GS levels or activity have been associated with neurodegenerative diseases, with these alterations attributed to oxidative post-translational modifications of the protein, in particular tyrosine nitration. In this study, we expressed and purified human GS (HsGS) and performed an in-depth analysis of its oxidative inactivation by peroxynitrite (ONOO−) in vitro. We found that ONOO− exposure led to a dose-dependent loss of HsGS activity, the oxidation of cysteine, methionine, and tyrosine residues and also the nitration of tryptophan and tyrosine residues. Peptide mapping by LC-MS/MS through combined H216O/H218O trypsin digestion identified up to 10 tyrosine nitration sites and five types of dityrosine cross-links; these modifications were further scrutinized by structural analysis. Tyrosine residues 171, 185, 269, 283, and 336 were the main nitration targets; however, tyrosine-to-phenylalanine HsGS mutants revealed that their sole nitration was not responsible for enzyme inactivation. In addition, we observed that ONOO− induced HsGS aggregation and activity loss. Thiol oxidation was a key modification to elicit aggregation, as it was also induced by hydrogen peroxide treatment. Taken together, our results indicate that multiple oxidative events at various sites are responsible for the inactivation and aggregation of human GS.

Atherosclerosis is a chronic inflammatory disease and a leading cause of mortality. It is characterized by arterial wall plaques that contain high levels of cholesterol and other lipids and activated leukocytes covered by a fibrous cap of extracellular matrix (ECM). The ECM undergoes remodelling during atherogenesis, with increased expression of aggrecan, a proteoglycan that binds low-density-lipoproteins (LDL). Aggrecan levels are regulated by proteases, including a disintegrin and metalloproteinase with thrombospondin motifs 1 (ADAMTS1). Activated leukocytes release myeloperoxidase (MPO) extracellularly, where it binds to proteins and proteoglycans. Aggrecan may therefore mediate colocalization of MPO and LDL. MPO generates hypochlorous acid (HOCl) and chloramines (RNHCl species, from reaction of HOCl with amines on amino acids and proteins) that damage LDL and proteins, but effects on aggrecan have not been examined. The present study demonstrates that HOCl cleaves truncated (G1-IGD-G2) recombinant human aggrecan at specific sites within the IGD domain, with these being different from those induced by ADAMTS1 which also cleaves within this region. Irreversible protein cross-links are also formed dose-dependently. These effects are limited by the HOCl scavenger methionine. Chloramines including those formed on amino acids, proteins, and ECM materials induce similar damage. HOCl and taurine chloramines inactivate ADAMTS1 consistent with a switch from proteolytic to oxidative aggrecan fragmentation. Evidence is also presented for colocalization of aggrecan and HOCl-generated epitopes in advanced human atherosclerotic plaques. Overall, these data show that HOCl and chloramines can induce specific modifications on aggrecan, and that these effects are distinct from those of ADAMTS1.

The pentose phosphate pathway (PPP) is a key metabolic pathway. The oxidative phase of this process involves three reactions catalyzed by glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconolactonase (6PGL) and 6-phosphogluconate dehydrogenase (6PGDH) enzymes. The first and third steps (catalyzed by G6PDH and 6PGDH, respectively) are responsible for generating reduced nicotinamide adenine dinucleotide phosphate (NAPDH), a key cofactor for maintaining the reducing power of cells and detoxification of both endogenous and exogenous oxidants and electrophiles. Despite the importance of these enzymes, little attention has been paid to the fact that these proteins are targets of oxidants. In response to oxidative stimuli metabolic pathways are modulated, with the PPP often up-regulated in order to enhance or maintain the reductive capacity of cells. Under such circumstances, oxidation and inactivation of the PPP enzymes could be detrimental. Damage to the PPP enzymes may result in a downward spiral, as depending on the extent and sites of modification, these alterations may result in a loss of enzymatic activity and therefore increased oxidative damage due to NADPH depletion. In recent years, it has become evident that the three enzymes of the oxidative phase of the PPP have different susceptibilities to inactivation on exposure to different oxidants. In this review, we discuss existing knowledge on the role that these enzymes play in the metabolism of cells, and their susceptibility to oxidation and inactivation with special emphasis on NADPH production. Perspectives on achieving a better understanding of the molecular basis of the oxidation these enzymes within cellular environments are given.