Objective. Aminothiols (glutathione (GSH), cysteinylglycine (CG)) may play an important role in the pathogenesis of coronavirus disease 2019 (COVID-19), but the possible association of these indicators with the severity of COVID-19 has not yet been investigated. Methods. The total content ( t ) and reduced forms ( r ) of aminothiols were determined in patients with COVID-19 ( n = 59 ) on admission. Lung injury was characterized by computed tomography (CT) findings in accordance with the CT0-4 classification. Results. Low tGSH level was associated with the risk of severe COVID-19 ( tGSH ≤ 1.5   μ M , mild vs. moderate/severe: risk   ratio   RR = 3.09 , p = 0.007 ) and degree of lung damage ( tGSH ≤ 1.8   μ M , CT < 2 vs. CT ≥ 2 : RR = 2.14 , p = 0.0094 ). The rGSH level showed a negative association with D-dimer levels ( ρ = − 0.599 , p = 0.014 ). Low rCG level was also associated with the risk of lung damage ( rCG ≤ 1.3   μ M , CT < 2 vs. CT ≥ 2 : RR = 2.28 , p = 0.001 ). Levels of rCG ( ρ = − 0.339 , p = 0.012 ) and especially tCG ( ρ = − 0.551 , p = 0.004 ) were negatively associated with platelet count. In addition, a significant relationship was found between the advanced oxidation protein product level and tGSH in patients with moderate or severe but not in patients with mild COVID-19. Conclusion. Thus, tGSH and rCG can be seen as potential markers for the risk of severe COVID-19. GSH appears to be an important factor to oxidative damage prevention as infection progresses. This suggests the potential clinical efficacy of correcting glutathione metabolism as an adjunct therapy for COVID-19.

The rats with neurodegenerative brain disorder induced by administration of a toxic fragment of beta-amyloid demonstrate weakened endothelium-dependent dilation of cerebral vessels, which attested to impaired production of endothelial NO. At the same time, toxic beta-amyloid fragment induced the formation of NO depots in the walls of cerebral vessels, which indirectly attests to NO overproduction in the brain tissue. Preadaptation to hypoxia prevented endothelial dysfunction and improved the efficiency of NO storage. Our results suggest that adaptation to hypoxia protects the brain from various changes in NO production during neurodegenerative damage.

Cerebral ischemia has previously been shown to cause a systemic decrease in levels of the reduced forms of low-molecular-weight aminothiols [cysteine (Cys), homocysteine (Hcy), and glutathione (GSH)] in blood plasma. In this study, we examined the effect of beta-adrenergic receptor (β-AR) antagonists metoprolol (Met) and nebivolol (Neb) on the redox status of these aminothiols during acute cerebral ischemia in rats. We used a model of global cerebral ischemia (bilateral occlusion of common carotid arteries with hypotension lasting for 10 minutes). The antagonists were injected 1 hour before surgery. Total and reduced Cys, Hcy, and GSH levels were measured 40 minutes after the start of reperfusion. Neb (0.4 and 4 mg/kg) and Met (8 and 40 mg/kg) treatment increased the levels of reduced aminothiols and the global methylation index in the hippocampus. The treatments also prevented any decrease in reduced aminothiol levels in blood plasma during ischemia. Although both of these drugs eliminated delayed postischemic hypoperfusion, only Neb reduced neuronal damage in the hippocampus. The results indicate an essential role of β1-AR blockage in the maintenance of redox homeostasis of aminothiols in the plasma and brain during acute cerebral ischemia.

These results suggest that plasma low-molecular-weight thiols are actively involved in oxidation reactions at early stages of cerebral ischaemia; therefore, their reduced forms or redox state may serve as a sensitive indicator of acute cerebrovascular insufficiency.