Design, synthesis and screening studies of potent thiazol-2-amine derivatives as fibroblast growth factor receptor 1 inhibitors.

Fibroblast growth factor receptor 1 (FGFR1) a tyrosine kinase receptor, plays important roles in angiogenesis, embryonic development, cell proliferation, cell differentiation, and wound healing. The FGFR isoforms and their receptors (FGFRs) considered as a potential targets and under intense research to design potential anticancer agents. Fibroblast growth factors (FGF's) and its growth factor receptors (FGFR) plays vital role in one of the critical pathway in monitoring angiogenesis. In the current study, quantitative pharmacophore models were generated and validated using known FGFR1 inhibitors. The pharmacophore models were generated using a set of 28 compounds (training). The top pharmacophore model was selected and validated using a set of 126 compounds (test set) and also using external validation. The validated pharmacophore was considered as a virtual screening query to screen a database of 400,000 virtual molecules and pharmacophore model retrieved 2800 hits. The retrieved hits were subsequently filtered based on the fit value. The selected hits were subjected for docking studies to observe the binding modes of the retrieved hits and also to reduce the false positives. One of the potential hits (thiazole-2-amine derivative) was selected based the pharmacophore fit value, dock score, and synthetic feasibility. A few analogues of the thiazole-2-amine derivative were synthesized. These compounds were screened for FGFR1 activity and anti-proliferative studies. The top active compound showed 56.87% inhibition of FGFR1 activity at 50 µM and also showed good cellular activity. Further optimization of thiazole-2-amine derivatives is in progress.

Anthrax lethal factor inhibitors as potential countermeasure of the infection.

Anthrax Lethal Factor (LF) is a zinc-dependent metalloprotease, one of the virulence factor of anthrax infection. Three forms of the anthrax infection have been identified: cutaneous (through skin), gastrointestinal (through alimentary tract), and pulmonary (by inhalation of spores). Anthrax toxin is composed of protective antigen (PA), lethal factor (LF), and edema factor (EF). Protective antigen mediates the entry of Lethal Factor/Edema Factor into the cytosol of host cells. Lethal factor (LF) inactivates mitogen-activated protein kinase kinase inducing cell death, and EF is an adenylyl cyclase impairing host defenses. In the past few years, extensive studies are undertaken to design inhibitors targeting LF. The current review focuses on the small molecule inhibitors targeting LF activity and its structure activity relationships (SAR).

Ligand-based and structure-based approaches in identifying ideal pharmacophore against c-Jun N-terminal kinase-3.

Structure and ligand based pharmacophore modeling and docking studies carried out using diversified set of c-Jun N-terminal kinase-3 (JNK3) inhibitors are presented in this paper. Ligand based pharmacophore model (LBPM) was developed for 106 inhibitors of JNK3 using a training set of 21 compounds to reveal structural and chemical features necessary for these molecules to inhibit JNK3. Hypo1 consisted of two hydrogen bond acceptors (HBA), one hydrogen bond donor (HBD), and a hydrophobic (HY) feature with a correlation coefficient (r²) of 0.950. This pharmacophore model was validated using test set containing 85 inhibitors and had a good r² of 0.846. All the molecules were docked using Glide software and interestingly, all the docked conformations showed hydrogen bond interactions with important hinge region amino acids (Gln155 and Met149)and these interactions were compared with Hypo1 features. The results of ligand based pharmacophore model (LBPM)and docking studies are validated each other. The structure based pharmacophore model (SBPM) studies have identified additional features, two hydrogen bond donors and one hydrogen bond acceptor. The combination of these methodologies is useful in designing ideal pharmacophore which provides a powerful tool for the discovery of novel and selective JNK3 inhibitors.

Insilico studies on anthrax lethal factor inhibitors: pharmacophore modeling and virtual screening approaches towards designing of novel inhibitors for a killer.

Bacillus anthracis is a causative organism of anthrax. The main reason to use anthrax as a bioweapon is the combination of the spore's durability and the lethal toxaemia of the vegetative stage. In anthrax infection, lethal factor (LF) is playing crucial role in causing cell death, by inhibiting pathways that rely on this kinase family. The combination of vaccine and antibiotics is preferred as an effective treatment for this target. Till date, no small molecule inhibitor is identified as a drug on the target. In this study, we have performed pharmacophore modeling and docking studies to identify a novel small molecule inhibitor to target the Anthrax LF. The best pharmacophore model is used to screen approximately 2M drug-like small molecule database and yielded 2543 hits. Docking studies of the pharmacophore hits on to the active site of Anthrax LF resulted 120 structurally diverse hits. Out of 120 hits, based on synthetic feasibility, 17 hits are selected for further synthesis and pharmacological screening. In due course, we will publish the updated results.

Design, synthesis, and discovery of novel non-peptide inhibitor of Caspase-3 using ligand based and structure based virtual screening approach.

Caspase-3 belonging to a family of cysteine proteases is main executioner of apoptotic cascade pathway. The inhibitors of this protein are useful in the treatment of cardiomyopathy and neurodegenerative diseases. For the discovery of novel Caspase-3 non-peptide inhibitors from Maybridge database, ligand based and structure based virtual screening methods were used. Quantitative 3D pharmacophore models were generated using 25 known inhibitors of Caspase-3 and it was used as initial screen to retrieve the hits from the database. These compounds with high estimated activity were analyzed for drug like properties and docking studies were performed, to study the interaction between new hits and active site. One of the hits (AW01208), with good predictions was selected for synthesis and biological screening. This compound showed an inhibition activity against Caspase-3 in SKNH cell lines.