Ligand-based Pharmacophore Modelling Approach Research Articles

Synthesized Drug from Medicinal Plant phytochemicals Effectively Targets ECM1 Gene Mutations in Ulcerative Colitis

: Ulcerative colitis (UC); an inflammatory bowel disease primarily affects the mucosa of the colon. Depending on its mode of appearance, it can affect either the entire colon or even the distal rectum. UC can manifest in both genders and every generation, but most generally appear in people between the ages of 15 and 30. The extracellular matrix protein-1 (ECM1) gene is an important candidate, mutations leading to tissue damage in patients with ECM1 single-nucleotide polymorphisms are likely to intensify tissue damage caused by Metalloproteinase9 resulting in UC. In this analysis, approval for the synthesis of Chemical Compound was obtained from the scientific committee of the Department of Traditional Chinese Medicine, Qilu Hospital, China. Several derivatives used as UC therapy were selected to build the pharmacophore model, using a ligand-based pharmacophore modeling approach and virtual screenings were done for the identification of suitable drug compounds. The selected compound was then synthesized in-vitro and validated using the molecular docking technique. The synthesized compound fulfills all the characteristics of the non-toxic existence of other drug-likeness laws. The specific interactive amino acids found in the docked complex are arginine (ARG):47, lysine (LYS):54, phenylalanine (PHE):141, aspargine (ASN):51, serine (SER):219, histadine (HIS):144, PHE:214, valine(VAL):220, tyrosine(TYR):145, and TYR:284. The interaction of the synthesized compound with mutated TYR:284 of ECM1 confirmed the viability and safety of a drug molecule as a medication in Ulcerative Colitis care. In the future, its validity can be explored in the laboratory and this synthesized compound can be used as a medication target in clinical studies against TYR:284 mutation in the ECM1 gene.

Studies on ligand-based pharmacophore modeling approach in identifying potent future EGFR inhibitors

Epidermal growth factor receptor (EGFR) is a validated drug target for cancer chemotherapy. Mutations in EGFR are directly linked with the development of drug resistance and this has led for the development of newer drugs in quest for more efficacious inhibitors. The current research is focused on identifying potential and safe molecules as EGFR inhibitors by using both structure and ligand based computational approaches. In quest for finding newer moieties, we have developed a pharmacophore model utilizing drugs like lazertinib, osimertinib, nazartinib, avitinib, afatininb, and talazoparib that are known to inhibit EGFR along with their downstream signaling. Ligand-based pharmacophore model have been developed to screen the ZINC database through ZINCPharmer webserver. The server has identified 9482 best possible ligands with high pharmacophoric similarity i.e., RMSD value less than 0.2 Å. The top 10 ligands with the criteria of dock score(s) and interactions were further subjected to in silico ADMET studies giving two plausible ligands that were further subjected to Molecular Dynamics and MM/PBSA free energy calculations to ensure stability to the target site. Results deduced by in silico work in the current study may be corroborated biologically in the future. The current work, therefore, provides ample opportunity for computational and medicinal chemists to work in allied areas to facilitate the design and development of novel and more efficacious EGFR inhibitors for future experimental studies.

Pharmacophore Modelling of Vanillin Derivatives, Favipiravir, Chloroquine, Hydroxychloroquine, Monolaurin and Tetrodotoxin as MPro inhibitors of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2)

Ligand-based pharmacophore modelling approach using four established antiviral drugs, namely remdesivir, lopinavir, ritonavir and hydroxychloroquine were analysed for COVID-19 inhibitors as training sets. Twenty vanillin derivatives together with monolaurin were used as test sets to evaluate potential as SARS-CoV-2 inhibitors. Structure-based pharmacophore modelling approach was also performed using Protein Data Bank information: PDB-5RE6, 5REX and 5RFZ in order to analyse the binding site and ligand-protein complex interactions. The pharmacophore modelling mode of 5RE6 displayed two Hydrogen Bond Acceptors (HBA) and one Hydrophobic (HY) interaction. Besides, the pharmacophore model of 5REX showed two HBA and two HY interactions. Finally, the pharmacophore model of 5RFZ showed three HBA and one HY interaction. Based on ligand-based approach, 20 Schiff-based vanillin derivatives, namely vanillin associated with methyl-6- aminopyridine-3-carboxylate (1), sepiapterin (2), 6-aminopyridine-3-carboxylic acid (3), 6-aminopyridine-2-carboxylic acid (4), pemoline (5), α-phenylglycine (6), 2-amino-4-hydroxy-3-methylpentanoic acid (7), 4-hydroxyphenylglycine (8), β-homoserine (9), allylglycine (10), oxamic acid (11) benzophenone hydrazine (12), 2-aminoadipic acid (13), D-alanyl-D-alanine (14), p-bromophenylalanine (15), nicotinic hydrazide (16), 4-hydroxybenzhydrazide (17), benzohydrazide (18), isonicotinic hydrazide (19), and phenylhydrazine (20) showed strong MPro inhibition activity. This was due to their good alignment and common features to PDB-5RE6. Similarly, monolaurin and tetrodotoxin displayed some significant activity against SARS-CoV-2. From structure-based approach, vanillin derivatives (1) to (12) displayed some potent MPro inhibition against SARS-CoV-2. Favipiravir, chloroquine and hydroxychloroquine also showed some significant MPro inhibition. Favipiravir showed good alignment and common pharmacophore features to PDB- 5RFZ, whereas chloroquine and hydroxychloroquine showed good alignment and common pharmacophore features to PDB-5REX.

De-Novo Ligand Design against Mutated Huntington Gene by Ligand-based Pharmacophore Modeling Approach.

Huntington's disease is characterized by three side effects, including motor disturbances, psychiatric elements, and intellectual weakness. The onset for HD has nonlinear converse associations with the number of repeat sequences of the polyglutamine mutations, so that younger patients have a tendency for longer repeats length. This HD variation is because of the development of a polyglutamine (CAG) repeats in the exon 1 of the Huntingtin protein. In the present study, a few derivatives utilized as a part of the treatment of HD, are used to create the pharmacophore model and based on the features of the pharmacophore model; an attempt is made to design the de-novo drug for the HD protein. HD protein structure was built and docked with the novel ligand, based on shared feature pharmacophore model, through a ligand-based pharmacophore modeling approach. The novel ligand contains 1 HBAs, 2 HBDs, and 2 aromatic rings. It fulfills all the properties of certain drug-likeness rules, non-toxic in nature. In the docked complex, the common interactive amino acids identified are SER 1035, ALA 1062, MET 1068, LEU 1031, and THR 1036, which confirmed the validity and stability of a ligand molecule to be used as a drug in the treatment of Huntington's disease. A novel ligand can be used in clinical trials as a drug molecule against the mutations of HD gene and in laboratory procedures for efficacy analysis.

Pharmacophore-based virtual screening approach for identification of potent natural modulatory compounds of human Toll-like receptor 7

Toll-like receptor 7 (TLR7) is a transmembrane glycoprotein playing very crucial role in the signaling pathways involved in innate immunity and has been demonstrated to be useful in fighting against infectious disease by recognizing viral ssRNA & specific small molecule agonists. In order to find novel human TLR7 (hTLR7) modulators, computational ligand-based pharmacophore modeling approach was used to identify the molecular chemical features required for the modulation of hTLR7 protein. A training set of 20 TLR7 agonists with their known experimental activity was used to create pharmacophore model using 3D-QSAR pharmacophore generation (HypoGen algorithm) module in Discovery Studio. The best developed hypothesis consists of four pharmacophoric features namely, one hydrogen bond donor (HBD), one ring aromatic (RA), and two hydrophobic (HY) character. The developed hypothesis was then validated by different methods such as cost analysis, test set method, and Fischer’s test method for consistency. Hence, this validated model was further employed for screening of natural hit compounds from InterBioScreen Natural product database, consisting of more than 60,000 natural compounds and derivatives. The screened hit compounds were subsequently filtered by Lipinski’s rule of 5, ADME and toxicity parameters and molecular docking studies to remove the false positive rates. Finally, molecular docking analysis led to identification of the (3a′S,6a′R)-3′-(3,4-dihydroxybenzyl)-5′-(3,4-dimethoxyphenethyl)-5-ethyl-3′,3a′-dihydro-2′H-spiro[indoline-3,1′-pyrrolo[3,4-c]pyrrole]-2,4′,6′(5′H,6a′H)-trione (Compound ID: STOCK1N-65837) as potent hTLR7 modulator due to its better docking score and molecular interactions compared to other compounds. The result of virtual screening was further validated using molecular dynamics (MD) simulation analysis. Thus, a 30 ns MD simulation analysis revealed high stability and effective binding of STOCK1N-65837 within the binding site of hTLR7. Therefore, the present study provides confidence for the utility of the selected chemical feature based pharmacophore model to design novel TLR7 modulators with desired biological activity.

A phenotypic approach to the discovery of compounds that promote non-amyloidogenic processing of the amyloid precursor protein: Toward a new profile of indirect β-secretase inhibitors

Dysregulation of the Amyloid Precursor Protein (APP) processing leading to toxic species of amyloid β peptides (Aβ) is central to Alzheimer's disease (AD) etiology. Aβ peptides are produced by sequential cleavage of APP by β-secretase (BACE-1) and γ-secretase. Lysosomotropic agent, chloroquine (CQ), has been reported to inhibit Aβ peptide production. However, this effect is accompanied by an inhibition of lysosome-mediated degradation pathways. Following on from the promising activity of two series of APP metabolism modulators derived from CQ, we sought to develop new series of compounds that would retain the inhibitory effects on Aβ production without altering lysosome functions. Herein, we applied a ligand-based pharmacophore modeling approach coupled with de novo design that led to the discovery of a series of biaryl compounds. Structure-activity relationship studies revealed that minor modifications like replacing a piperidine moiety of compound 30 by a cyclohexyl (compound 31) allowed for the identification of compounds with the desired profile. Further studies have demonstrated that compounds 30 and 31 act through an indirect mechanism to inhibit β-secretase activity. This work shows that it is possible to dissociate the inhibitory effect on Aβ peptide secretion of CQ-derived compounds from the lysosome-mediated degradation effect, providing a new profile of indirect β-secretase inhibitors.

Pharmacophore Based Virtual Screening Approach to Identify Selective PDE4B Inhibitors.

Phosphodiesterase 4 (PDE4) has been established as a promising target in asthma and chronic obstructive pulmonary disease. PDE4B subtype selective inhibitors are known to reduce the dose limiting adverse effect associated with non-selective PDE4B inhibitors. This makes the development of PDE4B subtype selective inhibitors a desirable research goal. To achieve this goal, ligand based pharmacophore modeling approach is employed. Separate pharmacophore hypotheses for PDE4B and PDE4D inhibitors were generated using HypoGen algorithm and 106 PDE4 inhibitors from literature having thiopyrano [3,2-d] Pyrimidines, 2-arylpyrimidines, and triazines skeleton. Suitable training and test sets were created using the molecules as per the guidelines available for HypoGen program. Training set was used for hypothesis development while test set was used for validation purpose. Fisher validation was also used to test the significance of the developed hypothesis. The validated pharmacophore hypotheses for PDE4B and PDE4D inhibitors were used in sequential virtual screening of zinc database of drug like molecules to identify selective PDE4B inhibitors. The hits were screened for their estimated activity and fit value. The top hit was subjected to docking into the active sites of PDE4B and PDE4D to confirm its selectivity for PDE4B. The hits are proposed to be evaluated further using in-vitro assays.

Discovery of the first inhibitors of bacterial enzyme d-aspartate ligase from Enterococcus faecium (Aslfm)

The d-aspartate ligase of Enterococcus faecium (Aslfm) is an attractive target for the development of narrow-spectrum antibacterial agents that are active against multidrug-resistant E. faecium. Although there is currently little available information regarding the structural characteristics of Aslfm, we exploited the knowledge that this enzyme belongs to the ATP-grasp superfamily to target its ATP binding site. In the first design stage, we synthesized and screened a small library of known ATP-competitive inhibitors of ATP-grasp enzymes. A series of amino-oxazoles derived from bacterial biotin carboxylase inhibitors showed low micromolar activity. The most potent inhibitor compound 12, inhibits Aslfm with a Ki value of 2.9 μM. In the second design stage, a validated ligand-based pharmacophore modeling approach was used, taking the newly available inhibition data of an initial series of compounds into account. Experimental evaluation of the virtual screening hits identified two novel structural types of Aslfm inhibitors with 7-amino-9H-purine (18) and 7-amino-1H-pyrazolo[3,4-d]pyrimidine (30 and 34) scaffolds, and also with Ki values in the low micromolar range. Investigation the inhibitors modes of action confirmed that these compounds are competitive with respect to the ATP molecule. The binding of inhibitors to the target enzyme was also studied using isothermal titration calorimetry (ITC). Compounds 6, 12, 18, 30 and 34 represent the first inhibitors of Aslfm reported to date, and are an important step forward in combating infections due to E. faecium.

In silico Screening for Identification of Novel Aurora Kinase Inhibitors by Molecular Docking, Dynamics Simulations and Ligand-Based Hypothesis Approaches

Aurora kinase family members are involved in a wide variety of cell cycle events including centrosome separation, cytokinesis, kinetochore formation, spindle assembly, chromosomal segregation and microtubule dynamics. Typically, dysfunction of Aurora proteins is associated with aneuploidy, cell death and mitotic arrest, leading to tumorigenesis. This spurred a vast interest to identify pharmacologically active small-molecule inhibitors of Aurora proteins. In this study, we isolated four novel inhibitors through virtual screening and docking analyses. These hits were subsequently characterized by molecular dynamic simulations to monitor their binding stabilities at ATP binding site. To aid characterizing novel and more potent inhibitors for Aurora kinases, we explored selective features of our ligand dataset by ligand-based pharmacophore modeling approach. The best pharmacophore model was then employed for performing virtual screenings of libraries isolated from Princeton and Uorsy databases. On the basis of common pharmacophore features, Lipinski’s rule of five, absorption, distribution, metabolism and elimination properties, hits were short listed and refined by molecular dockings. Finally, the selected compounds were validated on the basis of binding capabilities, consensus scoring and activity values. We propose that the novel inhibitors described in this study may warrant characterization in designing active lead for clinical studies that may serve as anticancer drugs in future.