Type II pneumocytes are the target of SARS-CoV-2 which alters their redox homeostasis to increase reactive oxygen species (ROS). Melatonin (MT) has antioxidant proprieties and protects mitochondrial function. Here we evaluated whether the treatment with MT compensated for the redox homeostasis alteration in serum from COVID-19 patients. We determined oxidative stress (OS) markers such as carbonyls, glutathione (GSH), total antioxidant capacity (TAC), thiols, nitrites (NO2–), lipid peroxidation (LPO), and thiols groups in serum. We also studied the enzymatic activities of glutathione peroxidase (GPx), -S-transferase (GST), reductase (GR), thioredoxin reductase (TrxR), extracellular superoxide dismutase (ecSOD) and peroxidases. There was a significant increase in LPO and carbonyls (p≤0.03) and a decrease in TAC, NO2–, thiols, GSH, (p<0.001) in COVID-19 patients. The activities of the ecSOD, TrxR, GPx, GST, GR and peroxidases were decreased (p≤ 0.04). The treatment with MT favored the activity of the antioxidant enzymes which contributed to increase TAC and restored the lost redox homeostasis. MT also modulated glucose homeostasis functioning as a glycolytic agent and inhibited the Warburg effect. Thus, MT restores the redox homeostasis which is altered in COVID-19 patients and can be used as adjuvant therapy in the SARS-CoV-2 infection.

Infective endocarditis (IE) results from infections by gram-positive bacteria, and, in this condition, the redox homeostasis is lost by overproduction of H2O2, leading to overstimulation of the immune system and up- regulation of the production of proinflammatory cytokines. The aim of this preliminary study of three cases with IE, was to evaluate the levels of oxidative biomarkers and of the enzymatic and non-enzymatic antioxidant systems, in subjects with IE. This is a preliminary retrospective analytical study of cases that had undergone aortic valve replacement surgery that was complicated by IE. We determined malondialdehyde (MDA), total antioxidant capacity (TAC), carbonyl groups, glutathione (GSH), thiols and the nitrate/nitrite ratio (NO3−/NO2−) in homogenized tissue of cardiac valves. We also measured the activities of GST, GPx, GR and TrxR. The super oxide dismutase (SOD) isoforms and peroxidase activities were determined using native gels. There were increases in the activities of antioxidant enzymes such as GST, SOD isoforms and peroxidases (p=0.01) and decreases in oxidative stress markers such as GSH, TAC, (p=0.01); however, MDA was increased (p=0.01). The results suggest that loss of the intricate redox homeostasis system in the aortic valve of patients with IE may favor the bacterial process and cause damage probably leading to a fatal outcome.

SARS-CoV-2 is an obligatory intracellular pathogen that requires of a lipid bilayer membrane for its transport, to build its nucleocapsid envelope and to fuse with the host cell. The biological membranes are constituted by phospholipids (PLs) and vitamin E (Vit E) protects them from oxidative stress (OS). The aim of this study was to demonstrate if the treatment with Vit E restores the modified profile of the FA in PLs in serum from patients with coronavirus disease-19 (COVID-19). We evaluated Vit E, total fatty acids (TFA), fatty acid of the phospholipids (FAPL), total phospholipids (TPLs), 8-isoprostane, thromboxane B2 (TXB2), prostaglandins (PGE2 and 6-keto-PGF1α), interleukin-6 (IL-6) and C-reactive protein (CRP) in serum from 22 COVID-19 patients before and after treatment with Vit E and compared the values with those from 23 healthy subjects (HS). COVID-19 patients showed a decrease in Vit E, TPLs, FAPL and TFA in serum in comparison to HS (p≤0.01) and Vit E treatment restored their levels (p≤0.04). Likewise, there was an increase IL-6 and CRP in COVID-19 patients in comparison with HS (p≤0.001) and the treatment with Vit E decreased their levels (p≤0.001). Treatment with Vit E contributes to restore the modified profile of the PLs in the SARS-CoV-2 infection and this leads to a decrease of OS and of the inflammatory process.