Insight into crystal structures and identification of potential styrylthieno[2,3-b]pyridine-2-carboxamidederivatives against COVID-19 Mpro through structure-guided modeling and simulation approach.

Anti-SARS-CoV-2 drugs are urgently needed to prevent the pandemic and for immunization. Their protease inhibitor treatment for COVID-19 has been used in clinical trials. In Calu-3 and THP1 cells, 3CL SARS-CoV-2 Mpro protease is required for viral expression, replication, and the activation of the cytokines IL-1, IL-6, and TNF-. The Mpro structure was chosen for this investigation because of its activity as a chymotrypsin-like enzyme and the presence of a cysteine-containing catalytic domain. Thienopyridine derivatives increase the release of nitric oxide from coronary endothelial cells, which is an important cell signaling molecule with antibacterial activity against bacteria, protozoa, and some viruses. Using DFT calculations, global descriptors are computed from HOMO-LUMO orbitals; the molecular reactivity sites are analyzed from an electrostatic potential map. NLO properties are calculated, and topological analysis is also part of the QTAIM studies. Both compounds 1 and 2 were designed from the precursor molecule pyrimidine and exhibited binding energies (-14.6708 kcal/mol and -16.4521 kcal/mol). The binding mechanisms of molecule 1 towards SARS-COV-2 3CL Mpro exhibited strong hydrogen bonding as well as Vdw interaction. In contrast, derivative 2 was bound to the active site protein's active studied that several residues and positions, including (His41, Cys44, Asp48, Met49, Pro52, Tyr54, Phe140, Leu141, Ser144, His163, Ser144, Cys145, His164, Met165, Glu166, Leu167, Asp187, Gln189, Thr190, and GLn192) are critical for the maintenance of inhibitors inside the active pocket. Molecular docking and 100 ns MD simulation analysis revealed that Both compounds 1 and 2 with higher binding affinity and stability toward the SARS-COV-2 3CL Mpro protein. Binding free energy calculations and other MD parameters support the finding.Communicated by Ramaswamy H. Sarma.

Crystal structure and Hirshfeld surface analysis of 5-acetyl-3-amino-6-methyl-N-phenyl-4-[(E)-2-phenyl-ethen-yl]thieno[2,3-b]pyridine-2-carbox-amide.

The asymmetric unit of the title compound, C25H21N3O2S, comprises four mol-ecules. Their conformations differ primarily in the orientations of the styryl and the N-phenyl-carboxamido groups. In the crystal, inter-molecular N-H⋯N, C-H⋯O and C-H⋯S hydrogen-bonding contacts as well a C-H⋯π(ring) inter-actions lead to the formation of a layer structure parallel to (010). Hirshfeld surface analysis revealed that H⋯H inter-actions represent the main contributions to the crystal packing.

Crystal structure and Hirshfeld surface analysis of ethyl 2-({5-acetyl-3-cyano-6-methyl-4-[(E)-2-phenyl-ethen-yl]pyridin-2-yl}sulfan-yl)acetate.

In the title mol-ecule, C21H20N2O3S, the styryl and ester substituents are displaced to opposite sides of the plane of the pyridine ring. In the crystal, C-H⋯O hydrogen bonds form chains extending parallel to the a-axis direction, which pack with partial inter-calation of the styryl and ester substituents. A Hirshfeld surface analysis indicates that the most significant contributions to the crystal packing are from H⋯H (43.6%), C⋯H/H⋯C (15.6%), O⋯H/H⋯O (14.9%) and N⋯H/H⋯N (11.2%) contacts.

Crystal structure and Hirshfeld surface analysis of 2-{[7-acetyl-4-cyano-6-hy-droxy-8-(4-meth-oxy-phen-yl)-1,6-dimethyl-5,6,7,8-tetra-hydro-iso-quino-lin-3-yl]sulfan-yl}-N-phenyl-acetamide.

The title mol-ecule, C29H29N3O4S, adopts a conformation with the two phenyl substituents disposed on opposite sides of the mean plane of the iso-quinoline unit. In the crystal, corrugated layers of mol-ecules are formed by N-H⋯O, C-H⋯N and C-H⋯S hydrogen bonds together with C-H⋯π(ring) inter-actions. These layers are connected by C-H⋯O contacts. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (45.2%), C⋯H/H⋯C (20.2%), O⋯H/H⋯O (15.8%) and N⋯H/H⋯N (11.0%) inter-actions.

Crystal structure and Hirshfeld surface analysis of 2-{[7-acetyl-8-(4-chloro-phen-yl)-4-cyano-6-hy-droxy-1,6-dimethyl-5,6,7,8-tetra-hydro-isoquinolin-3-yl]sulfan-yl}-N-(4-chloro-phen-yl)acetamide.

In the title mol-ecule, C28H25Cl2N3O3S, the heterocyclic portion of the tetra-hydro-iso-quinoline unit is planar while the cyclo-hexene ring adopts a twist-boat conformation. The two 4-chloro-phenyl groups extend away from one side of this unit while the hydroxyl and acetyl groups extend away from the opposite side and form an intra-molecular O-H⋯O hydrogen bond. The crystal packing consists of layers parallel to the bc plane. A Hirshfeld surface analysis of the crystal structure indicates that the most important contributions to the crystal packing are from H⋯H (37.3%), Cl⋯H/H⋯Cl (17.6%), O⋯H/H⋯O (11.1%), C⋯H/H⋯C (10.9%) and N⋯H/H⋯N (9.7%) inter-actions.