1,4,9,9-tetramethyloctahydro-4,7-(epoxymethano)azulen-5(1H)-one, a natural product as a potential inhibitor of COVID-19: Extraction, crystal structure, and virtual screening approach

In the present work, we describe the extraction of a natural product namely 1,4,9,9-tetramethyloctahydro-4,7-(epoxymethano)azulen-5(1H)-one, and its structure was confirmed by single crystal X-ray diffraction analysis. The conformations of the 5-, 6-, and 7-membered rings in the title compound, C15H24O2, have been probed by a Cremer-Pople puckering analysis. C—H···O hydrogen bonds generate chains in the crystal that stretch along the c-axis direction. The Hirshfeld surface analysis method was used to stabilize the crystal packing of the natural compound. Accompanied by experimental studies, quantum chemical calculations were also performed to compare the structural elucidation and the results of these geometrical parameters exhibited excellent agreement. The compound was also docked with several drug targets of the SARS-CoV-2 virus and found to show the best binding with the main protease enzyme, having a binding energy of -12.31 kcal/mol and interacting with His41 and Cys145 residues. The dynamic stability deciphered the complex to be stable with an average RMSD of 3.8 Å. The compound dynamics with the enzyme showed the compound conformation to be highly stable. The intermolecular binding free energy determined the compound-main protease enzyme to show high interaction energy of < 40 kcal/mol. Together, these studies demonstrate the compound to be a lead structure against SARS-CoV-2.

1,4,9,9-tetramethyloctahydro-4,7-(epoxymethano)azulen-5(1H)-one, a natural product as a potential inhibitor of COVID-19: Extraction, crystal structure, and virtual screening approach.

In the present work, we describe the extraction of a natural product namely 1,4,9,9-tetramethyloctahydro-4,7-(epoxymethano)azulen-5(1H)-one, and its structure was confirmed by single crystal X-ray diffraction analysis. The conformations of the 5-, 6-, and 7-membered rings in the title compound, C15H24O2, have been probed by a Cremer-Pople puckering analysis. C-H···O hydrogen bonds generate chains in the crystal that stretch along the c-axis direction. The Hirshfeld surface analysis method was used to stabilize the crystal packing of the natural compound. Accompanied by experimental studies, quantum chemical calculations were also performed to compare the structural elucidation and the results of these geometrical parameters exhibited excellent agreement. The compound was also docked with several drug targets of the SARS-CoV-2 virus and found to show the best binding with the main protease enzyme, having a binding energy of -12.31 kcal/mol and interacting with His41 and Cys145 residues. The dynamic stability deciphered the complex to be stable with an average RMSD of 3.8 Å. The compound dynamics with the enzyme showed the compound conformation to be highly stable. The intermolecular binding free energy determined the compound-main protease enzyme to show high interaction energy of < 40 kcal/mol. Together, these studies demonstrate the compound to be a lead structure against SARS-CoV-2.

Repurposing antibiotics as potent multi-drug candidates for SARS-CoV-2 delta and omicron variants: molecular docking and dynamics.

There is a daunting public health emergency due to the emergence and rapid global spread of the new omicron variants of SARS-CoV-2. The variants differ in many characteristics, such as transmissibility, antigenicity and the immune system of the human hosts' shifting responses. This change in characteristics raises concern, as it leads to unknown consequences and also raises doubts about the efficacy of the currently available vaccines. As of March 2022, there are five variants of SARS-CoV-2 disseminating: the alpha, the beta, the gamma, the delta and the omicron variant. The omicron variant has more than 30 mutations on the spike protein, which is used by the virus to enter the host cell and is also used as a target for the vaccines. In this work, we studied the possible anti-COVID-19 effect of two molecules by molecular docking using Autodock Vina and molecular dynamic simulations using Gromacs 2020 software. We docked amoxicillin and clavulanate to the main protease (Mpro), the RNA-dependent RNA polymerase (RdRp) and the spike protein receptor-binding domain (SRBD) of the wild type with the two variants (delta and omicron) of SARS-CoV-2. The docking results show that the ligands bound tightly with the SRBD of the omicron variant, while the dynamic simulation revealed the ability of amoxicillin to bind to the SRBD of both variants' delta and omicron. The high number of mutations that occurred in both variants increases the affinity of amoxicillin towards them. Communicated by Ramaswamy H. Sarma.

Potential SARS-CoV-2 RdRp inhibitors of cytidine derivatives: Molecular docking, molecular dynamic simulations, ADMET, and POM analyses for the identification of pharmacophore sites.

The RNA-dependent RNA polymerase (RdRp) of SARS-CoV-2 is one of the optimum targets for antiviral drug design and development. The hydroxyl groups of cytidine structures were modified with different aliphatic and aromatic groups to obtain 5´-O-acyl and 2´,3´-di-O-acyl derivatives, and then, these derivatives were employed in molecular modeling, antiviral prediction, molecular docking, molecular dynamics, pharmacological and POM studies. Density functional theory (DFT) at the B3LYP/6-31G++ level analyzed biochemical behavior and molecular electrostatic potential (MESP) of the modified cytidine derivatives. The antiviral parameters of the mutated derivatives revealed promising drug properties compared with those of standard antiviral drugs. Molecular docking has determined binding affinities and interactions between the cytidine derivatives and SARS-CoV-2 RdRp. The modified derivatives strongly interacted with prime Pro620 and Lys621 residues. The binding conformation and interactions stability were investigated by 200 ns of molecular dynamics simulations and predicted the compounds to firmly dock inside the RdRp binding pocket. Interestingly, the binding residues of the derivatives were revealed in high equilibrium showing an enhanced binding affinity for the molecules. Intermolecular interactions are dominated by both Van der Waals and electrostatic energies. Finally, the pharmacokinetic characterization of the optimized inhibitors confirmed the safety of derivatives due to their improved kinetic properties. The selected cytidine derivatives can be suggested as potential inhibitors against SARS-CoV-2. The POM Theory supports the hypothesis above by confirming the existence of an antiviral (Oδ--O'δ-) pharmacophore site of Hits.

One-pot synthesis, X-ray crystal structure, and identification of potential molecules against COVID-19 main protease through structure-guided modeling and simulation approach.

Although antimicrobial resistance before the Covid-19 pandemic is a top priority for global public health, research is already ongoing on novel organic compounds with antimicrobial and antiviral properties in changing medical environments in connection with Covid 19. Thanks to the Biginelli reaction, which allows the synthesis of pyrimidine compounds, blockers of calcium channels, antibodies, antiviral, antimicrobial, anti-inflammatory, or antioxidant therapeutic compounds were investigated. In this paper, we aim to present Biginelli's synthesis, its therapeutic properties, and the structural-functional relationship in the test compounds that allows the synthesis of antimicrobial compounds. Both the DFT and TD-DFT computations of spectral data, molecular orbitals (HOMO, LUMO) analysis, and electrostatic potential (MEP) surfaces are carried out as an add-on to synthetic research. Hirshfeld surface analysis was also used to segregate the different intermolecular hydrogen bonds involved in the molecular packing strength. Natural Bond Orbital (NBO) investigation endorses the existence of intermolecular interactions mediated by lone pair, bonding, and anti-bonding orbitals. The dipole moment, linear polarizability, and first hyperpolarizabilities have been explored as molecular parameters. All findings based on DFT exhibit the best consistency with experimental findings, implying that synthesized molecules are highly stable. To better understand the binding mechanism of the SARS-CoV-2 Mpro, we performed molecular docking, molecular dynamics (MD) simulations, and binding free energy calculations.

Exploring Structural Mechanism of COVID-19 Treatment with Glutathione as a Potential Peptide Inhibitor to the Main Protease: Molecular Dynamics Simulation and MM/PBSA Free Energy Calculations Study.

The 2019-novel coronavirus has unfolded everywhere in the world and obliged a billion human beings in open confinement, whereas many treatments, and vaccines have been proposed towards this pandemic. The main protease (Mpro) is an attractive drug target due to the fact that it is the essential protein for virus invasion. This research tests in silico the effect of five vitamins towards Mpro, by employing molecular docking (MD), molecular dynamics simulation (MDS) with molecular mechanics-Poisson-Boltzmann surface area (MM-PBSA) studies. To achieve this work, we have applied some software's as Autodock Vina, Discovery Studio Visualizer, APBS, and GROMACS. The inhibitors used were decided entirely on the basis of their importance in the production of red blood cells that prevent anemia, in lymphocyte immune system responses, in the regulation of reactive oxygen species production, such as tocopherol (vitamin E), thiamine (vitamin B1), pantothenic acid (vitamin B5), pyridoxine (vitamin B6), biotin (vitamin B7), and glutathione (GSH). The best inhibitor pose established at the highest repetition ratio (RR) and the minimal affinity energy value (MEV), then the best selected inhibitor was considered to MDS. The results indicate that GSH is the leading inhibitor model among the other tested vitamins in the active site of Mpro with a RR value of 94% and MEV of - 5.5 kcal/mol, its RMSD, RMSF, Rg, and hydrogen bonds show stability with Mpro. Furthermore, thiamine, biotin, and tocopherol are viewed as satisfying inhibitors to Mpro, but pyridoxine was observed as the weakest inhibitor. Based on our result, we could recommend the usage of glutathione and vitamin B family as a supportive strategy for feasible remedy of COVID-19 virus.