Synthesis and molecular docking study of pyrazole clubbed oxazole as antibacterial agents

Evaluation of dual potentiality of 2,4,5-trisubstituted oxazole derivatives as aquaporin-4 inhibitors and anti-inflammatory agents in lung cells

Inflammation is a multifaceted "second-line" adaptive defense mechanism triggered by exo/endogenous threating stimuli and inter-communicated by various inflammatory key players. Unresolved or dysregulated inflammation in lungs results in manifestation of diseases and leads to irreparable damage. Aquaporins (AQPs) are a ubiquitously expressed superfamily of intrinsic transmembrane water channel proteins that modulate the fluid homeostasis. In addition to their conventional functions, AQPs have clinical relevance to inflammation prevailing under the infectious conditions of various lung diseases and this proclaims them as appropriate biomarkers to be targeted. Hence an endeavor was undertaken to identify potential ligands to target AQP4 for the treatment of lung diseases. Oxazole being a versatile bio-potent core, a series of 2,4,5-trisubstituted oxazoles 3a-j were synthesized by a Lewis acid mediated reaction of aroylmethylidene malonates with nitriles. In silico studies conducted using the protein data bank (PDB) structure 3gd8 for AQP4 revealed that compound 3a would serve as a suitable candidate to inhibit AQP4 in human lung cells (NCI-H460). Further, in vitro studies demonstrated that compound 3a could effectively inhibit AQP4 and inflammatory cytokines in lung cells and hence it may be considered as a viable drug candidate for the treatment of various lung diseases.

Synthesis, characterization, anticancer and in silico studies of a pyrazole-tethered thiazolidine-2,4-dione derivative

A new pyrazole-tethered thiazolidine-2,4-dione derivative (8) has been synthesized by the Knoevenagel condensation of 3-(4-nitrophenyl)-1-phenyl-1H-pyrazole-4-carbaldehyde (4) and 3-(2,4-dioxothiazolidin-3-yl)propanenitrile (7). The structure of the final compound was confirmed by standard spectroscopic techniques including IR spectroscopy, ¹H-NMR spectroscopy, and ESI-MS mass spectrometry. Molecular features including frontier molecular orbital (HOMO-LUMO) energies, reactivity descriptors and molecular electrostatic potential (ESP) of the title molecule were determined using density functional theory (DFT) calculation. The in vitro cytotoxicity of both the intermediate (4) and final (8) compounds were investigated against cancerous (SW-480 and MCF-7) and normal (HEK-293) cell lines by MTT assay. Compound (8) displayed higher activity than (4) with higher sensitivity against breast cancer cell line and lesser toxicity. The experimental data were further complemented by docking and absorption, distribution, metabolism, and excretion (ADME) studies.Communicated by Ramaswamy H. Sarma.

Synthesis, Characterization, and Biological Evaluation of Novel N-{4-[(4-Bromophenyl)sulfonyl]benzoyl}-L-valine Derivatives

In this article, we present the design and synthesis of novel compounds, containing in their molecules an L-valine residue and a 4-[(4-bromophenyl)sulfonyl]phenyl moiety, which belong to N-acyl-α-amino acids, 4H-1,3-oxazol-5-ones, 2-acylamino ketones, and 1,3-oxazoles chemotypes. The synthesized compounds were characterized through elemental analysis, MS, NMR, UV/VIS, and FTIR spectroscopic techniques, the data obtained are in accordance with the assigned structures. Their purities were verified by reversed-phase HPLC. The new compounds were tested for antimicrobial action against bacterial and fungal strains for antioxidant activity by DPPH, ABTS, and ferric reducing power assays, and for toxicity on freshwater cladoceran Daphnia magna Straus. Furthermore, in silico studies were performed concerning the potential antimicrobial effect and toxicity. The results of antimicrobial activity, antioxidant effect, and toxicity assays, as well as of in silico analysis revealed a promising potential of N-{4-[(4-bromophenyl)sulfonyl]benzoyl}-L-valine and 2-{4-[(4-bromophenyl)sulfonyl]phenyl}-4-isopropyl-4H-1,3-oxazol-5-one for developing novel antimicrobial agents to fight Gram-positive pathogens, and particularly Enterococcus faecium biofilm-associated infections.

Conventional and microwave-assisted synthesis, anticancer evaluation, 99mTc-coupling and In-vivo study of some novel pyrazolone derivatives

New pyrazolone derivatives were successfully synthesized by both microwave-assisted and conventional techniques. Compound 3 (3-(3-Methyl-5-oxo-4,5-dihydro-1H-pyrazol-1-yl)-3-oxopropanehydrazide) displayed remarkable anti-cancer activity (IC₅₀ obtained at 8.71 and 10.63 µM for HCT-116 and MCF-7, respectively. Moreover, biodistribution study using radiolabeling approach revealed a remarked uptake of [^99mTc]Tc-compound 3 complex into tumour induced in mice. The biodistribution showed high accumulation in tumour tissues with T/NT of 6.92 after 60 min post injection. As a result of these promising data, the newly synthesized compounds especially compound 3 affords a potential radio-carrier that could be used as a tumour marker and can be used for cancer therapy after further preclinical studies.

Synthesis, In Silico and In Vitro Evaluation of Antimicrobial and Toxicity Features of New 4-[(4-Chlorophenyl)sulfonyl]benzoic Acid Derivatives

The multi-step synthesis, physico-chemical characterization, and biological activity of novel valine-derived compounds, i.e., N-acyl-α-amino acids, 1,3-oxazol-5(4H)-ones, N-acyl-α-amino ketones, and 1,3-oxazoles derivatives, bearing a 4-[(4-chlorophenyl)sulfonyl]phenyl moiety are reported here. The structures of the newly synthesized compounds were confirmed by spectral (UV-Vis, FT-IR, MS, ¹H- and ¹³C-NMR) data and elemental analysis results, and their purity was determined by RP-HPLC. The new compounds were assessed for their antimicrobial activity and toxicity to aquatic crustacean Daphnia magna. Also, in silico studies regarding their potential mechanism of action and toxicity were performed. The antimicrobial evaluation revealed that the 2-{4-[(4-chlorophenyl)sulfonyl]benzamido}-3-methylbutanoic acid and the corresponding 1,3-oxazol-5(4H)-one exhibited antimicrobial activity against Gram-positive bacterial strains and the new 1,3-oxazole containing a phenyl group at 5-position against the C. albicans strain.

Synthesis and Biological Evaluation of New N-Acyl-α-amino Ketones and 1,3-Oxazoles Derivatives

In order to develop novel bioactive substances with potent activities, some new valine-derived compounds incorporating a 4-(phenylsulfonyl)phenyl fragment, namely, acyclic precursors from N-acyl-α-amino acids and N-acyl-α-amino ketones classes, and heterocycles from the large family of 1,3-oxazole-based compounds, were synthesized. The structures of the new compounds were established using elemental analysis and spectral (UV-Vis, FT-IR, MS, NMR) data, and their purity was checked by reversed-phase HPLC. The newly synthesized compounds were evaluated for their antimicrobial and antibiofilm activities, for toxicity on D. magna, and by in silico studies regarding their potential mechanism of action and toxicity. The 2-aza-3-isopropyl-1-[4-(phenylsulfonyl)phenyl]-1,4-butanedione 4b bearing a p-tolyl group in 4-position exhibited the best antibacterial activity against the planktonic growth of both Gram-positive and Gram-negative strains, while the N-acyl-α-amino acid 2 and 1,3-oxazol-5(4H)-one 3 inhibited the Enterococcus faecium biofilms. Despite not all newly synthesized compounds showing significant biological activity, the general scaffold allows several future optimizations for obtaining better novel antimicrobial agents by the introduction of various substituents on the phenyl moiety at position 5 of the 1,3-oxazole nucleus.

In silico molecular docking studies of oxadiazole and pyrimidine bearing heterocyclic compounds as potential antimicrobial agents

Microbial resistance is a major problem faced by the scientific community. It has created an urgent need to develop antimicrobial agents with novel structures and mechanisms of action. With this aim, a series of novel 1,3,4-oxadiazoles bearing 3,4-dihydropyrimidine heterocyclic motifs 4a-l were designed and synthesized. One-pot Biginelli synthesis is pivotal due to the use of readily available chemicals, shorter reaction time, and ecofriendly synthesis with a good yield. The structures of the synthesized molecules were characterized and confirmed by infrared, ¹ H nuclear magnetic resonance (NMR), ¹³ C NMR, and mass spectroscopic techniques. The title compounds were screened against Gram-positive and -negative strains of bacteria and fungi using the Mueller-Hinton broth method. Compound 4d was found to be the most promising against Escherichia coli (12.5 µg/ml), whereas the same compound showed good activity against Staphylococcus aureus at a concentration of 50 µg/ml. Other compounds of the same series, 4c and 4h, displayed moderate activity against Streptococcus pyogenes at a concentration of 50 µg/ml. Furthermore, results of the antifungal activity tests revealed that compound 4i showed promising activity against all the strains of fungi, Candida albicans, Aspergillus niger, and Aspergillus clavatus, at concentrations of 100, 50, and 100 µg/ml, respectively. Molecular docking also showed that these compounds had a significant binding affinity (Glide docking score: -7.74 to -6.531) for DNA gyrase, engaging in a series of bonded and nonbonded interactions with residues lining the active site. The results of molecular docking study validated the experimental findings, thereby providing an initiation mark to optimize this motif using a structure-based drug design approach.