Omprakash Tanwar

Pyrazolines: A Biological Review

Pyrazoline is an important five membered nitrogen heterocycle, which has been extensively researched upon. The ring is quite stable and has inspired chemists to carry out various structural variations in the ring. This has propelled the development of distinct pyrazolines with an array of pharmacological activities viz. anti-inflammatory, analgesic, antimicrobial, anticancer, antidepressant etc. The review aims at highlighting this pharmacological diversity of pyrazolines. The review is a gist of latest work done describing the pharmacological aspects and potential of pyrazoline ring.

Recent Updates on Biological Activities of Oxadiazoles

Among the plethora of heterocyclic nucleus discovered, the oxadiazoles have also been explored extensively. The oxadiazole structure has been demonstrated to bear important biological activities such as anti-cancer, antiinflammatory, anti-tuberculosis, anti-malarial and anti-schistosomiasis etc. The presence of oxadiazole motifs in diverse types of compounds proves its importance in the field of medicinal chemistry. This review is complementary to earlier reviews and covers recent updates of various pharmacological aspects of oxadiazoles. To help the reader better know the context for these approaches, a summary of various aspects of background of related topic is presented.

Structure based virtual screening of MDPI database: discovery of structurally diverse and novel DPP-IV inhibitors.

Inhibition of dipeptidyl peptidase IV (DPP-IV) has been emerged as a promising approach for the treatment of type 2 diabetes (T2D). Structure based virtual screening (SBVS) of Molecular Diversity Preservation International (MDPI) database was performed using Glide and Gold against DPP-IV enzyme. Six promising hits were identified and tested for DPP-IV inhibition. Three compounds were found to be active at low micromolar concentration. The 3-(1-hydrazinyl-1-(phenylamino)ethyl)-4-hydroxy-1-methylquinolin-2(1H)-one (compound A) was found to be the most potent hit with an IC50 of 0.73 μM. These three compounds (A, B and D) were then assessed for their glucose lowering effects in glucose fed hyperglycemic female Wistar rats. The glucose lowering effects of compounds also confirms their potential as anti-diabetic agents. The present study demonstrates a successful utilization of in silico SBVS tools in identification of novel and potential DPP-IV inhibitor.

Novel hydrazine derivatives as selective DPP-IV inhibitors: findings from virtual screening and validation through molecular dynamics simulations

AbstractThe present study demonstrates and validates the discovery of two novel hydrazine derivatives as selective dipeptidyl peptidase-IV (DPP-IV) inhibitors. Virtual screening (VS) of publicly available databases was performed using virtual screening workflow (VSW) of Schrödinger software against DPP-IV and the most promising hits were selected. Selectivity was further assessed by docking the hits against homology modeled structures of DPP8 and DPP9. Two novel hydrazine derivatives were selected for further studies based on their selectivity threshold. To assess their correct binding modes and stability of their complexes with enzyme, molecular dynamic (MD) simulation studies were performed against the DPP-IV protein and the results revealed that they had a better binding affinity towards DPP-IV as compared to DPP 8 and DPP 9. The binding poses were further validated by docking these ligands with different softwares (Glide and Gold). The proposed binding modes of hydrazines were found to be similar to sitagliptine and alogliptine. Thus, the study reveals the potential of hydrazine derivatives as highly selective DPP-IV inhibitors. FigureStructures of sitagliptine and the novel hydrazine identified by screening

Pharmacophore model generation and 3D-QSAR analysis of N-acyl and N-aroylpyrazolines for enzymatic and cellular B-Raf kinase inhibition

A successful 3D-QSAR study has been performed for amino-substituted N-acyl and N-aroylpyrazolines as B-Raf kinase inhibitors by means of a common five-point pharmacophore model. In this study, highly predictive 3D-QSAR models have been developed for B-Raf kinase inhibition and pERK inhibition using AADRR-2 and AADRR-6 hypothesis, respectively. The best models showed statistically outstanding values of 0.97, 0.95 and 0.91, 0.87 for r2 and q2 for AADRR-2 and AADRR-6 hypothesis, respectively. The validation of the PHASE model was done by dividing the dataset into training and test set. From the QSAR model, it can implicated that electron-withdrawing and hydrophobic groups are not advantageous for both enzymatic and cellular activities. However, H-bond donor characteristic is favorable for cellular inhibition and unfavorable for enzymatic inhibition. Based on the findings of the 3D-QSAR study, novel and promising compounds for B-Raf kinase inhibition can be synthesized.

Pharmacophore based virtual screening, synthesis and SAR of novel inhibitors of Mycobacterium sulfotransferase

A planned 3D-pharmacophore mapping was carried out on the basis of chemical features associated with known Stf0 inhibitors. Four models (model 1-4) were obtained after GASP (Genetic Algorithm Similarity Program) refinement of seven models (D-1 to D-7) generated by using DISCOtech. The selected GASP model-1 has two hydrogen bond acceptor, two hydrogen bond donor and four hydrophobic points. This model was used for virtual screening (VS) of large public databases along with in house generated knowledge base database. VS followed by docking of selected compounds on Stf0 active site was carried and pose analysis done. Seven hits were identified after all the computational studies, of which 2 hits were synthesized along with their analogs and evaluated for antitubercular activity. IH-45 was found promising after in vitro assay.

Structural comparison of Mtb-DHFR and h-DHFR for design, synthesis and evaluation of selective non-pteridine analogues as antitubercular agents

Tuberculosis is an infectious disease that affects millions of population every year. Mtb-DHFR is a validated target that is vital for nucleic acids biosynthesis and therefore DNA formation and cell replication. This paper report identification and synthesis of novel compounds for selective inhibition of Mtb-DHFR and unleash the selective structural features necessary to inhibit the same. Virtual screening of databases was carried out to identify novel compounds on the basis of difference between the binding pockets of the two proteins. Consensus docking was performed to improve upon the results and best ten hits were selected. Hit 1 was subjected to analogues design and the analogues were docked against Mtb-DHFR. From the docking results 11 compounds were selected for synthesis and biological assay against H37Rv. Most potent compound (IND-07) was tested for selectivity using enzymatic assay against Mtb-DHFR and h-DHFR. The compounds were found to have good inhibitory activity (25-200 µM) against H37Rv and in enzyme assay against Mtb-DHFR and h-DHFR the compound was found selective towards Mtb-DHFR with selectivity index of 6.53. This work helped to identify indole moiety as novel scaffold for development of novel selective Mtb-DHFR inhibitors as antimycobacterial agents.