Discovery of hit molecules targeting allosteric site of hepatitis C virus NS5B polymerase.

Nonstructural protein 5B (NS5B), the RNA-dependent RNA polymerase of Hepatitis C Virus (HCV), plays a key role in viral amplification and is an attractive and most explored target for discovery of new therapeutic agents for Hepatitis C. Though safe and effective, NS5B inhibitors were launched in 2013 (Sovaldi) and 2014 (Harvoni, Viekira Pak), the high price tags of these medications limit their use among poor people in developing countries. Hence, still there exists a need for cost-effective and short duration anti-HCV agents especially those targeting niche patient population who were non-respondent to earlier therapies or with comorbid conditions. The present study describes the discovery of novel non-nucleoside (NNI) inhibitors of NS5B using a series of rational drug design techniques such as virtual screening, scaffold matching and molecular docking. 2D and 3D structure based virtual screening technique identified 300 hit compounds. Top 20 hits were screened out from identified hits using molecular docking technique. Four molecules, that are representative of 20 hits were evaluated for binding affinity under in vitro conditions using surface plasmon resonance-based assay and the results emphasized that compound with CoCoCo ID: 412075 could exhibit good binding response toward NS5B and could be a potential candidate as NS5B inhibitor.Communicated by Ramaswamy H. Sarma.

Development and Application of a Virtual Screening Protocol for the Identification of Multitarget Fragments.

In this study, we report on a virtual ligand screening protocol optimized to identify fragments endowed with activity at multiple targets. Thanks to this protocol, we were able to identify a fragment that displays activity in the low-micromolar range at both ß-secretase 1 (BACE-1) and glycogen synthase kinase 3ß (GSK-3ß). These two structurally and physiologically unrelated enzymes likely contribute, through different pathways, to the onset of Alzheimer's disease (AD). Therefore, their simultaneous inhibition holds great potential in exerting a profound effect on AD. In perspective, the strategy outlined herein can be adapted to other target combinations.

Assessment of microtubule depolymerization property of flavonoids isolated from Tanacetum gracile in breast cancer cells by biochemical and molecular docking approach.

The chemical investigation of the bioactive nonpolar fractions of Tanacetum gracile afforded two flavonoid analogues namely, 5-hydroxy-3,6,7,3',4'-pentamethoxyflavone (1) and 5,4'-dihydroxy-3,6,7,3',4'-tetramethoxyflavone (2) which were identical to the previously reported artemetin and chrysosplenetin respectively. The structure of the compounds was elucidated on the basis of spectroscopic evidences and they showed significant cytotoxic activity against human breast cancer cells (MCF-7 and T47D). Mechanism based study showed that the compounds modulated microtubule depolymerization by activating mitotic spindle checkpoint. Molecular docking at the colchicine binding pocket revealed that the compounds bind at α-ß interfacial site of tubulin, correlating binding interactions with probable inhibition mechanism. The study reveals important observations to generate improved flavonoids that leads to cell apoptosis. The compounds were also evaluated for absorption, metabolism and toxicity by online webserver admetSAR. The significant microtubule disassembling property and less toxicity paves way for consideration of the compounds as chemopreventive agents.

Combining dyad protonation and active site plasticity in BACE-1 structure-based drug design.

The ability of the BACE-1 catalytic dyad to adopt multiple protonation states and the conformational flexibility of the active site have hampered the reliability of computational screening campaigns carried out on this drug target for Alzheimer's disease. Here, we propose a protocol that, for the first time, combining quantum mechanical calculations, molecular dynamics, and conformational ensemble virtual ligand screening addresses these issues simultaneously. The encouraging results prefigure this approach as a valuable tool for future drug discovery campaigns.