Steroidal pyrazolines as a promising scaffold in drug discovery

Design, synthesis and molecular docking of novel D-ring substituted steroidal 4,5-dihydropyrazole thiazole derivatives that act as iNOS/COX-2 inhibitors with potent anti-inflammatory activity against LPS-induced RAW264.7 macrophage cells

Inflammation, an important biological protective response to tissue damage or microbial invasion, is considered to be an alarming signal for the progress of varied biological complications. Based on the previous reports in the literature that proved the noticeable efficacy of pyrazole and thiazole scaffold as well as nitrogen heterocyclic based compounds against acute and chronic inflammatory disease, a new set of novel D-ring substituted steroidal 4,5-dihydropyrazole thiazole derivatives were synthesized and evaluated their anti-inflammatory activities in vitro. Preliminary structure-activity relationship (SAR) analysis was conducted by their inhibitory activities against nitric oxide (NO) release in lipopolysaccharide (LPS)-induced RAW 264.7 cells, and the optimal compound 12b [3β-hydroxy-pregn-5-en-17β-yl-5'- (o- chlorophenyl)- 1'-(4''- phenyl -[1'', 3'']- thiazol-2''- yl) - 4',5'-dihydro - 1'H-pyrazol - 3'- yl] exhibited more potent anti-inflammatory activity than the positive control treatment methylprednisolone (MPS), with an IC50 value of 2.59 μM on NO production and low cytotoxicity against RAW 264.7 cells. In further mechanism study, our results showed that compound 12b significantly suppressed the production of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and inhibited the expressions of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) through blocking NF-κB p65 nuclear translocation and phosphorylation of IκBα. Compound 12b also attenuated LPS-induced activation of c-Jun amino-terminal kinase (JNK) and p38 phosphorylation in RAW 264.7 cells. Molecular docking study revealed the strong binding affinity of compound 12b to the active site of the COX-2 proteins, which confirmed that compound 12b acted as an anti-inflammatory mediator. These results indicate that steroidal derivatives bearing 4,5-dihydropyrazole thiazole structure might be considered for further research and scaffold optimization in designing anti-inflammatory drugs and compound 12b might be a promising therapeutic anti-inflammatory drug candidate.

Pyrazoline scaffold: hit identification to lead synthesis and biological evaluation as antidiabetic agents

Background: Mining of novel scaffolds as potential DPP-IV inhibitors for future development of potential candidates as antidiabetic agents to address global issues. Methodology: The identified hit KB-10 from a previously reported study was taken as a lead for designing a library of analogues and screened initially based on in silico parameters and docking score. A series of selected (2[4-(1-acetyl-5-phenyl-4,5-dihydro-1H-pyrazol-3-yl)phenoxy]-1-phenylethanone derivatives were synthesized and evaluated through in vitro studies. Compounds KB-23, KB-22 and KB-06 were found to be as potent, with IC₅₀ values of 0.10 μM, 0.12 μM and 0.35 μM, respectively. They also showed promising antihyperglycemic potential in in vivo studies (oral glucose tolerance tests) in Wistar rats. Conclusion: This work establishes pyrazoline analogues KB-23, KB-22 and KB-06 as promising starting points for the development of potential antidiabetic agents.

Discovery of multi-target mur enzymes inhibitors with anti-mycobacterial activity through a Scaffold approach

In the present study, we generated a ligand-based scaffold model from a known bioactive datasets of mur enzymes of other species to identify multi-targeting inhibitors as antitubercular agents. Compounds in the ChEMBL database were first filtered to screen for substructure molecules ofMtb's multi-target enzymes. 5'-O-(5-Amino-5-deoxy-β-D-ribofuranosyl)uridine has been identified as scaffold to develop compounds targeting Mtb's mur enzymes. A library of Murcko scaffolds was extracted and evaluated for their in-silico antitubercular activity against Mtb's mur enzymes. The screened compounds were subjected to molecular docking, molecular dynamics simulations, MM/PBSA calculation with Mtb's mur enzymes to evaluate the mechanism of interaction to assess inhibitory activity against the target protein. The results revealed that 15 compounds have higher docking scores and good interactions with multiple mur enzymes of Mtb. From the docking analysis, compound HPT had the best score and binding affinity with the all mur enzymes. Further, protein-ligand interactions were evaluated by molecular dynamics simulations to assess their stability throughout 100 ns period. From the MD trajectory, we calculated RMSD, RMSF, Rg, PCA, DCCM, FEL, hydrogen bonding, and vector motion. Furthermore, the binding free energies of the all nine mur enzymes with compound HPT exhibited good binding affinity might show the anti-mycobacterial activity. The compound HPT revealed from this computational study could act as potent anti-mycobacterial inhibitors and further serve as lead scaffolds to develop more potent pharmaceutical molecules targeting multiple mur enzymes of Mtb based on 5'-O-(5-Amino-5-deoxy-β-D-ribofuranosyl)uridine in the future. Communicated by Ramaswamy H. Sarma.

Synthesis, molecular docking, molecular dynamics and evaluation of Drug-Likeness properties of the fused N-Formyl pyrazoline substituted new dehydroepiandrosterone derivatives

The hybrid molecules bearing heterocyclic structures in the A or D rings of steroids have significant biological activity. 16 (E)-Hetereoarylidene steroids were synthesized from the reaction of different heteroaromatic carbaldehydes and trans-Dehydroepiandrosterone (DHEA) in a basic medium. Then, synthesis of the N-formyl pyrazoline substituted new DHEA derivatives were carried out from the reaction of hydrazine hydrate and 16 (E)-hetereoarylidene steroids. The structures of the synthesized compounds were elucidated by elemental analysis, FT-IR, ¹H NMR, and ¹³C NMR spectroscopy. To investigate the activation pathway of synthesized N-formyl pyrazoline substituted steroid derivatives, a molecular docking study was performed on human cytochrome P450-(CYP17A1: PDB ID 5IRQ) with the help of the free AutoDock Vina. 100 ns molecular dynamic simulation process was performed to monitor the behavior of the complex structure formed by CYP17A1 and to calculate the stability over time of 2a and 2d (-9.8 kcal/mol), which gave the lowest value according to the results obtained in the molecular docking study with AutoDock Vina. Accordingly, RMSD, RMSF, Rg, and SASA analyzes of 2a and 2d were performed, and MMPBSA was calculated. Lastly, the ADMET (absorption, distribution, metabolism, excretion, and toxicity) analyses of the novel steroid derivatives were investigated.Communicated by Ramaswamy H. Sarma.

Development of Halogenated Pyrazolines as Selective Monoamine Oxidase-B Inhibitors: Deciphering via Molecular Dynamics Approach

Halogens have been reported to play a major role in the inhibition of monoamine oxidase (MAO), relating to diverse cognitive functions of the central nervous system. Pyrazoline/halogenated pyrazolines were investigated for their inhibitory activities against human monoamine oxidase-A and -B. Halogen substitutions on the phenyl ring located at the fifth position of pyrazoline showed potent MAO-B inhibition. Compound 3-(4-ethoxyphenyl)-5-(4-fluorophenyl)-4,5-dihydro-1H-pyrazole (EH7) showed the highest potency against MAO-B with an IC₅₀ value of 0.063 µM. The potencies against MAO-B were increased in the order of –F (in EH7) > –Cl (EH6) > –Br (EH8) > –H (EH1). The residual activities of most compounds for MAO-A were > 50% at 10 µM, except for EH7 and EH8 (IC₅₀ = 8.38 and 4.31 µM, respectively). EH7 showed the highest selectivity index (SI) value of 133.0 for MAO-B, followed by EH6 at > 55.8. EH7 was a reversible and competitive inhibitor of MAO-B in kinetic and reversibility experiments with a Ki value of 0.034 ± 0.0067 µM. The molecular dynamics study documented that EH7 had a good binding affinity and motional movement within the active site with high stability. It was observed by MM-PBSA that the chirality had little effect on the overall binding of EH7 to MAO-B. Thus, EH7 can be employed for the development of lead molecules for the treatment of various neurodegenerative disorders.

Pyrazoline Hybrids as Promising Anticancer Agents: An Up-to-Date Overview

Pyrazolines are five-membered heterocycles possessing two adjacent nitrogens. They have attracted significant attention from organic and medicinal chemists due to their potent biological activities and the numerous possibilities for structural diversification. In the last decade, they have been intensively studied as targets for potential anticancer therapeutics, producing a steady yearly rise in the number of published research articles. Many pyrazoline derivatives have shown remarkable cytotoxic activities in the form of heterocyclic or non-heterocyclic based hybrids, such as with coumarins, triazoles, and steroids. The enormous amount of related literature in the last 5 years prompted us to collect all these published data from screening against cancer cell lines, or protein targets like EGFR and structure activity relationship studies. Therefore, in the present review, a comprehensive account of the compounds containing the pyrazoline nucleus will be provided. The chemical groups and the structural modifications responsible for the activity will be highlighted. Moreover, emphasis will be given on recent examples from the literature and on the work of research groups that have played a key role in the development of this field.