The COVID‐19 pandemic caused by the SARS‐CoV‐2 has mobilized scientific attention in search of a treatment. The cysteine‐proteases, main protease (Mpro) and papain‐like protease (PLpro) are important targets for antiviral drugs. In this work, we simulate the interactions between the Mpro and PLpro with Ebselen, its metabolites and derivatives with the aim of finding molecules that can potentially inhibit these enzymes. The docking data demonstrate that there are two main interactions between the thiol (−SH) group of Cys (from the protease active sites) and the electrophilic centers of the organoselenium molecules, i. e. the interaction with the carbonyl group (O=C … SH) and the interaction with the Se moiety (Se … SH). Both interactions may lead to an adduct formation and enzyme inhibition. Density Functional Theory (DFT) calculations with Ebselen indicate that the energetics of the thiol nucleophilic attack is more favorable on Se than on the carbonyl group, which is in accordance with experimental data (Jin et al. Nature , 2020, 582 , 289–293). Therefore, organoselenium molecules should be further explored as inhibitors of the SARS‐CoV‐2 proteases. Furthermore, we suggest that some metabolites of Ebselen (e. g. Ebselen diselenide and methylebselenoxide) and derivatives ethaselen and ebsulfur should be tested in vitro as inhibitors of virus replication and its proteases.

A monoselenoether ligand (PySeCH2Py) reacts with CoII, CuII, CuI and PdII resulting in the formation of molecular, polymeric or cyclometallated complexes depending on the starting material used and the reaction conditions applied.

No abstract

In the last 2 years, different pharmacological agents have been indicated as potential inhibitors of SARS-CoV-2 in vitro. Specifically, drugs termed as functional inhibitors of acid sphingomyelinase (FIASMAs) have proved to inhibit the SARS-CoV-2 replication using different types of cells. Those therapeutic agents share several chemical structure characteristics and some well-known representatives are fluoxetine, escitalopram, fluvoxamine, and others. Most of the FIASMAs are primarily used as effective therapeutic agents to treat different pathologies, therefore, they are natural drug candidates for repositioning strategy. In this review, we summarize the two main proposed mechanisms mediating acid sphingomyelinase (ASM) inhibition and how they can explain the inhibition of SARS-CoV-2 replication by FIASMAs. The first mechanism implies a disruption in the lysosomal pH fall as the endosome-lysosome moves toward the interior of the cell. In fact, changes in cholesterol levels in endosome-lysosome membranes, which are associated with ASM inhibition is thought to be mediated by lysosomal proton pump (ATP-ase) inactivation. The second mechanism involves the formation of an extracellular ceramide-rich domain, which is blocked by FIASMAs. The ceramide-rich domains are believed to facilitate the SARS-CoV-2 entrance into the host cells.

Background: SARS-CoV-2 main protease (Mpro or 3CLpro) and papain-like protease (PLpro) are common viral targets for repurposed drugs to combat COVID-19 disease. Recently, several anti-depressants (such as fluoxetine, venlafaxine and citalopram) belonging to the Selective Serotonin Reuptake Inhibitors (SSRIs) and the Serotonin-Norepinephrine Reuptake Inhibitors (SNRI) classes have been shown to in vitro inhibit viral replication. Aim: Investigate a possible action of fluoxetine and derivatives on SARS-CoV-2 protease sites. Methods: molecular docking was performed using AutoDock Vina. Both proteases structures and different drugs conformations were used to explore the possibility of SARS-CoV-2 inhibition on a Mpro or PLpro related pathway. Drug structures were obtained by optimization with the Avogadro software and MOPAC using PM6 method. Results were analysed on Discovery Studio Visualizer. Results: The results indicated that Mpro interacted in a thermodynamically favorable way with fluoxetine, venlafaxine, citalopram, atomoxetine, nisoxetine and norfluoxetine in the region of the active site, whether PLpro conformers did not come close to active site. Conclusion: In an in silico perspective, it is likely that the SSRIs and other anti-depressants could interact with Mpro and cause the enzyme to malfunction. Unfortunately, the same drugs did not present similar results on PLpro crystal, therefore no inhibition is expected on an in vitro trial. Anyway, in vitro test are necessary for the better understanding the links between SARS-CoV-2 proteases and anti-depressants.