In Silico Exploration of Novel Tubulin Inhibitors: A Combination of Docking and Molecular Dynamics Simulations, Pharmacophore Modeling, and Virtual Screening

Microtubules play a critical role in mitosis and cell division and are regarded as an excellent target for anticancer therapy. Although microtubule-targeting agents have been widely used in the clinical treatment of different human cancers, their clinical application in cancer therapy is limited by both intrinsic and acquired drug resistance and adverse toxicities. In a previous work, we synthesized compound 9IV-c, ((E)-2-(3,4-dimethoxystyryl)-6,7,8-trimethoxy-N-(3,4,5-trimethoxyphenyl)quinoline-4-amine) that showed potent activity against multiple human tumor cell lines, by targeting spindle formation and/or the microtubule network. Accordingly, in this study, to identify potent tubulin inhibitors, at first, molecular docking and molecular dynamics studies of compound 9IV-c were performed into the colchicine binding site of tubulin; then, a pharmacophore model of the 9IV-c-tubulin complex was generated. The pharmacophore model was then validated by Güner–Henry (GH) scoring methods and receiver operating characteristic (ROC) analysis. The IBScreen database was searched by using this pharmacophore model as a screening query. Finally, five retrieved compounds were selected for molecular docking studies. These efforts identified two compounds (b and c) as potent tubulin inhibitors. Investigation of pharmacokinetic properties of these compounds (b and c) and compound 9IV-c displayed that ligand b has better drug characteristics compared to the other two ligands.

Pharmacophore Modeling, Docking, and Molecular Dynamics Simulation of Flavonoids as Inhibitors of Urokinase-type Plasminogen Activator

The urokinase-type plasminogen activator (uPA) system plays a significant role in the invasion and metastasis of cancer cells. The present study was conducted to investigate natural product compounds as inhibitors and hit molecules of uPA using in-silico analysis. A pharmacophore model was built to screen the Indonesian Herbal Database (HerbalDB) to obtain inhibitors of different scaffolds. Based on the molecular docking score, four ligands were selected as potential uPA inhibitors. Subsequently, the stability of the ligand-uPA complex was analyzed using molecular dynamics (MD) simulation. An RMSD graph of the backbone protein and the RMSF values of the amino acid residues were also determined. In addition, the MM-PBSA method was applied to calculate the free binding energy. According to the results, Model_3, characterized by aromatic rings 23 (F1 and F2), cationic H-bond donor (F3), and metal ligator (F4) features, had an adequate goodness-of-hit score (GH). The four top-ranked ligands, isorhamnetin, rhamnetin, quercetin, and kaempferol, showed higher docking scores compared to the others. This study confirmed that isorhamnetin, rhamnetin, and kaempferol build stable complexes with uPA with lower binding energy than quercetin.

Assessment of Activity of Chalcone Compounds as Inhibitors of 3-Chymotrypsin Like Protease (3CLPro) of SARS-CoV-2: in Silico Study

The COVID-19 is still pandemic due to emerging of the various variant of concern of SARS-CoV2. Hence it is devastating the world, causing significant economic as well as social chaos. This needs great effort to search and develop effective alternatives along with vaccination. Therefore to continue drug discovery endeavors, we used chalcone derivatives to find an effective drug candidate against SARS-CoV2. Chalcone is a common simple scaffold that exists in many diets as well as in traditional medicine. Natural as well as synthetic chalcones have shown numerous interesting biological activities and are also effective in fighting various diseases. Hence various computational methods were applied to find out potential inhibitors of 3CLPro using a library of 3000 compounds of chalcones. Firstly the screening by structure-based pharmacophore model yielded 84 hits that were subjected to molecular docking. The top 10 docked compounds were characterized for stability by using 100 nanoseconds (ns) molecular dynamic (MD) simulation approach. Further, the binding free energy calculation by MMPBSA showed that four compounds bind to 3CLPro enzyme with high affinity i.e., -87.962(KJ/mol), -66.125 (KJ/mol), -59.589(KJ/mol), and -66.728(KJ/mol) respectively. Since chalcone is a common simple scaffold that is present in many diets as well as in traditional medicine, we suggest that screened compounds may emerge as promising drug candidates for SARS-CoV-2. These compounds may be investigated in vitro to evaluate the efficacy againstSARS-CoV-2.

Structure-Based Pharmacophore Modeling, Virtual Screening, Molecular Docking, ADMET, and Molecular Dynamics (MD) Simulation of Potential Inhibitors of PD-L1 from the Library of Marine Natural Products

Background: In the past decade, several antibodies directed against the PD-1/PD-L1 interaction have been approved. However, therapeutic antibodies also exhibit some shortcomings. Using small molecules to regulate the PD-1/PD-L1 pathway may be another way to mobilize the immune system to fight cancer. Method: 52,765 marine natural products were screened against PD-L1(PDBID: 6R3K). To identify natural compounds, a structure-based pharmacophore model was generated, following by virtual screening and molecular docking. Then, the absorption, distribution, metabolism, and excretion (ADME) test was carried out to select the most suitable compounds. Finally, molecular dynamics simulation was also performed to validate the binding property of the top compound. Results: Initially, 13 small marine molecules were screened based on the pharmacophore model. Then, two compounds were selected for further evaluation based on the molecular docking scores. After ADME and toxicity studies, molecule 51320 was selected for further verification. By molecular dynamics analysis, molecule 51320 maintains a stable conformation with the target protein, so it has the chance to become an inhibitor of PD-L1. Conclusions: Through structure-based pharmacophore modeling, virtual screening, molecular docking, ADMET approaches, and molecular dynamics (MD) simulation, the marine natural compound 51320 can be used as a small molecule inhibitor of PD-L1.

Molecular Modeling Insights into Upadacitinib Selectivity upon Binding to JAK Protein Family

Rheumatoid arthritis (RA) is a chronic disease characterized by bone joint damage and incapacitation. The mechanism underlying RA pathogenesis is autoimmunity in the connective tissue. Cytokines play an important role in the human immune system for signal transduction and in the development of inflammatory responses. Janus kinases (JAK) participate in the JAK/STAT pathway, which mediates cytokine effects, in particular interleukin 6 and IFNγ. The discovery of small molecule inhibitors of the JAK protein family has led to a revolution in RA therapy. The novel JAK inhibitor upadacitinib (RinvoqTM) has a higher selectivity for JAK1 compared to JAK2 and JAK3 in vivo. Currently, details on the molecular recognition of JAK1 by upadacitinib are not available. We found that characteristics of hydrogen bond formation with the glycine loop and hinge in JAKs define the selectivity. Our molecular modeling study could provide insight into the drug action mechanism and pharmacophore model differences in JAK isoforms.

Repositioning of Etravirine as a Potential CK1ε Inhibitor by Virtual Screening

CK1ε is a key regulator of WNT/β-catenin and other pathways that are linked to tumor progression; thus, CK1ε is considered a target for the development of antineoplastic therapies. In this study, we performed a virtual screening to search for potential CK1ε inhibitors. First, we characterized the dynamic noncovalent interactions profiles for a set of reported CK1ε inhibitors to generate a pharmacophore model, which was used to identify new potential inhibitors among FDA-approved drugs. We found that etravirine and abacavir, two drugs that are approved for HIV infections, can be repurposed as CK1ε inhibitors. The interaction of these drugs with CK1ε was further examined by molecular docking and molecular dynamics. Etravirine and abacavir formed stable complexes with the target, emulating the binding behavior of known inhibitors. However, only etravirine showed high theoretical binding affinity to CK1ε. Our findings provide a new pharmacophore for targeting CK1ε and implicate etravirine as a CK1ε inhibitor and antineoplastic agent.

Heterocyclic Moieties as HDAC Inhibitors: Role in Cancer Therapeutic

‘Epigenetic’ regulation of genes via post-translational modulation of proteins is a well explored approach for the disease therapies, particularly cancer chemotherapeutics. Histone deacetylases (HDACs) are one of the important epigenetic targets and are mainly responsible for balancing the acetylation/deacetylation of lysine amino acids on histone/nonhistone proteins along with histone acetyltransferase (HAT). HDAC inhibitors (HDACIs) have become an important biologically active compounds for the treatment of cancers due to cell cycle arrest, differentiation and apoptosis in tumor cells and thus leads to anticancer activity. Out of the four classes of HDAC i.e. Class I, II, III and IV, HDACIs act on Class-IV (Zinc dependent HDAC) and various FDA-approved drugs belong to this category. The required canonical pharmacophore model (zinc binding group, surface recognition cap and appropriate linker) supported by HDACIs, various heterocyclic moieties containing compounds exhibiting HDAC inhibitory activity and structure activity relationship of different synthetic derivatives reported during last twelve years have been summarized in this review.

Molecular Informatics of Trypanothione Reductase of Leishmania major Reveals Novel Chromen-2-One Analogues as Potential Leishmanicides

Trypanothione reductase (TR), a flavoprotein oxidoreductase is an important therapeutic target for leishmaniasis. Ligand-based pharmacophore modelling and molecular docking were used to predict selective inhibitors against TR. Homology modelling was employed to generate a three-dimensional structure of Leishmania major trypanothione reductase (LmTR). A pharmacophore model used to screen a natural compound library generated 42 hits, which were docked against the LmTR protein. Compounds with lower binding energies were evaluated via in silico pharmacological profiling and bioactivity. Four compounds emerged as potential leads comprising Karatavicinol (7-[(2E,6E,10S)-10,11-dihydroxy-3,7,11-trimethyldodeca-2,6-dienoxy]chromen-2-one), Marmin (7-[(E,6R)-6,7-dihydroxy-3,7-dimethyloct-2-enoxy]chromen-2-one), Colladonin (7-[[(4aS)-6-hydroxy-5,5,8a-trimethyl-2-methylidene-3,4,4a,6,7,8-hexahydro-1H-naphthalen-1-yl]methoxy]chromen-2-one), and Pectachol (7-[(6-hydroxy-5,5,8a-trimethyl-2-methylidene-3,4,4a,6,7,8-hexahydro-1H-naphthalen-1-yl)methoxy]-6,8-dimethoxychromen-2-one) with good binding energies of −9.4, −9.3, 8.8, and −8.5 kcal/mol, respectively. These compounds bound effectively to the FAD domain of the protein with some critical residues including Asp35, Thr51, Lys61, Tyr198, and Asp327. Furthermore, molecular dynamics simulations and molecular mechanics Poisson-Boltzmann surface area (MMPBSA) computations corroborated their strong binding. The compounds were also predicted to possess anti-leishmanial activity. The molecules serves as templates for the design of potential drug candidates and can be evaluated in vitro with optimistic results in producing plausible attenuating infectivity in macrophages.

A Search for Cyclin-Dependent Kinase 4/6 Inhibitors by Pharmacophore-Based Virtual Screening, Molecular Docking, and Molecular Dynamic Simulations

The G1 phase of cell cycle progression is regulated by Cyclin-Dependent Kinase 4 (CDK4) as well as Cyclin-Dependent Kinase 6 (CDK6), and the acivities of these enzymes are regulated by the catalytic subunit, cyclin D. Cell cycle control through selective pharmacological inhibition of CDK4/6 has proven to be beneficial in the treatment of estrogen receptor-positive (ER-positive) breast cancer, particularly improving the progression-free survival of patients. Thus, targeting specific inhibition on CDK4/6 is bound to increase therapeutic efficiency. This study aimed to obtain CDK4/6 inhibitors through a pharmacophore-based virtual screening of the ZINC15 purchasable compound database using the in silico method. The pharmacophore model was designed based on the FDA-approved cdk4/6 inhibitor structures, and molecular docking was performed to further screen the hit compounds obtained. A total of eight compounds were selected based on docking results and interactions with CDK4 and CDK6, using palbociclib as the reference drug. According to the results, the compounds of ZINC585292724 and ZINC585291674 were the best compounds based on free binding energy, as well as hydrogen bond stability, and, therefore, exhibit potential as starting points in the development of CDK4/6 inhibitors.

3D-PHARMACOPHORE MODELLING OF OMEGA-3 DERIVATIVES WITH PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR GAMMA AS AN ANTI-OBESITY AGENT

Objective: The aim of this work was to study the pharmacophore model of omega-3 derivatives with the PPAR-γ receptor using LigandScout 4.4.3 to investigate the important chemical interactions of complex structure. Methods: The methods consisted of structure preparation of nine chemical compounds derived from omega-3 fatty acids, database preparation, creating 3D Pharmacophore modelling, validation pharmacophore, and screening test compounds. Results: The result of the research showed that the omega-3 derivatives docosahexaenoic acid (DHA), when eicosapentaenoic acid (HPA), and docosapentaenoic acid (DPA) have the best pharmacophore fit values of 36.59; 36.56; and 36.56, respectively. According to the results of the pharmacophore study, the carbonyl and hydroxyl of the carboxylate functional groups become the active functional groups that exhibit hydrogen bonding interactions. While the alkyl chain (Ethyl and methyl groups) was the portion that can be modified to increase its activity. Conclusion: Omega-3 derivatives could be used as a lead drug for the powerful PPAR-γ receptor in the prevention and treatment of obesity.