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Rheumatoid Arthritis (RA) is an autoimmune disease caused by overproduction of pro-inflammatory cytokines. Janus Kinases (JAKs) mediate cytokines signaling through the Janus Kinase (JAK)/signal transducer and activator of transcription (STAT) signaling pathways. Clinical studies have shown that Janus kinase 1 (JAK1) mediated signaling plays a key role in synovial response in rheumatoid arthritis. Hence, the inhibition JAK1 is considered as an important therapeutic route for treatment of rheumatoid arthritis. In this study, we have performed three-dimensional quantitative structure-activity relationship (3 D-QSAR), molecular docking, molecular dynamics (MD) and free energy calculations on a series of pyrrolo[2,3-d]pyrimidin-4-amine JAK1 inhibitors. Molecular docking studies of the compounds 03, 13, 36 and 49 with JAK1 were performed to study the binding interactions. The binding conformations of the compounds from docking studies were selected based on binding energy and H-bond interactions and were used as initial structure for MD simulations. Using 3 D-QSAR techniques, a ligand-based comparative molecular field analysis (CoMFA) model (q2 = 0.5, r2 = 0.96) and a receptor-based CoMFA model (q2 = 0.78, r2 = 0.98) were developed. Analysis of the MD results of the most active compound (compound 49) with JAK1 showed the formation of H-bond interactions with residues Glu957, Leu959 and Gly887 and water-mediated H-bond interaction with Gly887 and His885. Based on the contour map analyses of the receptor-based CoMFA, a design strategy was proposed and was used for designing new JAK1 inhibitors. Four of the designed compounds (D57, D58, D98 and D99) showed predicted activity values (pIC50> 8.8) greater than the most active compound for JAK1. MM-PBSA based free energy calculations indicated that the designed compounds were able to form stable binding with JAK1 primarily through electrostatic interactions and van der Waal interactions. Collectively, the outcome of this study can be used to further the progress of JAK1 inhibition for the treatment of rheumatoid arthritis. Communicated by Ramaswamy H. Sarma

Janus kinases (JAKs) are a family of non-receptor kinases that play a key role in cytokine signaling and their aberrant activities are associated with the pathogenesis of various immune diseases. The JAK1 isoform plays an essential role in the types 1 and II interferon signaling and elicits signals from the interleukin-2, interleukin-4, gp130, and class 2 receptor families. It is ubiquitously expressed in humans and its overexpression has been linked with autoimmune diseases such as myeloproliferative neoplasm. Although JAK1 inhibitors such as Tofacitinib have been approved for medical use, the low potency and off-target effects of these inhibitors have limited their use and calls for the development of novel JAK1 inhibitors. In this study, we used computational methods on a series of pyrrolopyridine derivatives to design new JAK1 inhibitors. Molecular docking and molecular dynamics simulation methods were used to study the protein-inhibitor interactions. 3D-quantitative structure–activity relationship models were developed and were used to predict the activity of newly designed compounds. Free energy calculation methods were used to study the binding affinity of the inhibitors with JAK1. Of the designed compounds, seventeen of the compounds showed a higher binding energy value than the most active compound in the dataset and at least six of the compounds showed higher binding energy value than the pan JAK inhibitor Tofacitinib. The findings made in this study could be utilized for the further development of JAK1 inhibitors.

Overexpression and frequent mutations in FMS-like tyrosine kinase-3 (FLT3) are considered risk factors for severe acute myeloid leukemia (AML). Hyperactive FLT3 induces premature activation of multiple intracellular signaling pathways, resulting in cell proliferation and anti-apoptosis. We conducted the computational modeling studies of 40 pyrimidine-4,6-diamine-based compounds by integrating docking, molecular dynamics, and three-dimensional structure–activity relationship (3D-QSAR). Molecular docking showed that K644, C694, F691, E692, N701, D829, and F830 are critical residues for the binding of ligands at the hydrophobic active site. Molecular dynamics (MD), together with Molecular Mechanics Poison–Boltzmann/Generalized Born Surface Area, i.e., MM-PB(GB)SA, and linear interaction energy (LIE) estimation, provided critical information on the stability and binding affinity of the selected docked compounds. The MD study suggested that the mutation in the gatekeeper residue F691 exhibited a lower binding affinity to the ligand. Although, the mutation in D835 in the activation loop did not exhibit any significant change in the binding energy to the most active compound. We developed the ligand-based comparative molecular field analysis (CoMFA) and comparative molecular similarity index analysis (CoMSIA) models. CoMFA (q2 = 0.802, r2 = 0.983, and QF32 = 0.698) and CoMSIA (q2 = 0.725, r2 = 0.965 and QF32 = 0.668) established the structure–activity relationship (SAR) and showed a reasonable external predictive power. The contour maps from the CoMFA and CoMSIA models could explain valuable information about the favorable and unfavorable positions for chemical group substitution, which can increase or decrease the inhibitory activity of the compounds. In addition, we designed 30 novel compounds, and their predicted pIC50 values were assessed with the CoMSIA model, followed by the assessment of their physicochemical properties, bioavailability, and free energy calculation. The overall outcome could provide valuable information for designing and synthesizing more potent FLT3 inhibitors.

The G-protein coupled receptor kinase 2 (GRK2) regulates the desensitization of beta-adrenergic receptors (β-AR), and its overexpression has been implicated in heart failure. Hence, the inhibition of GRK2 is considered to be an important drug target for the treatment of heart failure. Due to the high sequence similarity of GRK2 with the A, G, and C family (AGC family) of kinases, the inhibition of GRK2 also leads to the inhibition of AGC kinases such as Rho-associated coiled-coil kinase 1 (ROCK1). Therefore, unraveling the mechanisms to selectively inhibit GRK2 poses an important challenge. We have performed molecular docking, three dimensional quantitative structure activity relationship (3D-QSAR), molecular dynamics (MD) simulation, and free energy calculations techniques on a series of 53 paroxetine-like compounds to understand the structural properties desirable for enhancing the inhibitory activity for GRK2 with selectivity over ROCK1. The formation of stable hydrogen bond interactions with the residues Phe202 and Lys220 of GRK2 seems to be important for selective inhibition of GRK2. Electropositive substituents at the piperidine ring and electronegative substituents near the amide linker between the benzene ring and pyrazole ring showed a higher inhibitory preference for GRK2 over ROCK1. This study may be used in designing more potent and selective GRK2 inhibitors for therapeutic intervention of heart failure.

Gastrointestinal stromal tumors (GISTs) are the most common Mesenchymal Neoplasm of the gastrointestinal tract. The tumorigenesis of GISTs has been associated with the gain-of-function mutation and abnormal activation of the stem cell factor receptor (c-KIT) and platelet-derived growth factor receptor alpha (PDGFR&alpha, ) kinases. Hence, inhibitors that target c-KIT and PDGFR&alpha, could be a therapeutic option for the treatment of GISTs. The available approved c-KIT/PDGFR&alpha, inhibitors possessed low efficacy with off-target effects, which necessitated the development of potent inhibitors. We performed computational studies of 48 pyrazolopyridine derivatives that showed inhibitory activity against c-KIT and PDGFR&alpha, to study the structural properties important for inhibition of both the kinases. The derivative of phenylurea, which has high activities for both c-KIT (pIC50 = 8.6) and PDGFR&alpha, (pIC50 = 8.1), was used as the representative compound for the dataset. Molecular docking and molecular dynamics simulation (100 ns) of compound 14 was performed. Compound 14 showed the formation of hydrogen bonding with Cys673, Glu640, and Asp810 in c-KIT, and Cys677, Glu644, and Asp836 in PDGFR&alpha, The results also suggested that Thr670/T674 substitution in c-KIT/PDGFR&alpha, induced conformational changes at the binding site of the receptors. Three-dimensional quantitative structure&ndash, activity relationship (3D-QSAR) models were developed based on the inhibitors. Contour map analysis showed that electropositive and bulky substituents at the para-position and the meta-position of the benzyl ring of compound 14 was favorable and may increase the inhibitory activity against both c-KIT and PDGFR&alpha, Analysis of the results suggested that having bulky and hydrophobic substituents that extend into the hydrophobic pocket of the binding site increases the activity for both c-KIT and PDGFR&alpha, Based on the contour map analysis, 50 compounds were designed, and the activities were predicted. An evaluation of binding free energy showed that eight of the designed compounds have potential binding affinity with c-KIT/PDGFR&alpha, Absorption, distribution, metabolism, excretion and toxicity (ADMET) and synthetic feasibility tests showed that the designed compounds have reasonable pharmaceutical properties and synthetic feasibility. Further experimental study of the designed compounds is recommended. The structural information from this study could provide useful insight into the future development of c-KIT and PDGFR&alpha, inhibitors.

In the rapidly evolving coronavirus disease (COVID-19) pandemic, repurposing existing drugs and evaluating commercially available inhibitors against druggable targets of the virus could be an effective strategy to accelerate the drug discovery process. The 3C-Like proteinase (3CLpro) of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been identified as an important drug target due to its role in viral replication. The lack of a potent 3CLpro inhibitor and the availability of the X-ray crystal structure of 3CLpro (PDB-ID 6LU7) motivated us to perform computational studies to identify commercially available potential inhibitors. A combination of modeling studies was performed to identify potential 3CLpro inhibitors from the protease inhibitor database MEROPS (https://www.ebi.ac.uk/merops/index.shtml). Binding energy evaluation identified key residues for inhibitor design. We found 15 potential 3CLpro inhibitors with higher binding affinity than that of an α-ketoamide inhibitor determined via X-ray structure. Among them, saquinavir and three other investigational drugs aclarubicin, TMC-310911, and faldaprevir could be suggested as potential 3CLpro inhibitors. We recommend further experimental investigation of these compounds.