4-Alkoxy-3-arylfuran-2(5H)-ones as inhibitors of tyrosyl-tRNA synthetase: Synthesis, molecular docking and antibacterial evaluation

Synthesis and Bio-Evaluation of Natural Butenolides-Acrylate Conjugates

A series of novel 3-aryl-4-hydroxy-2(5H) furanone-acrylate hybrids were designed and synthesized based on the natural butenolides and acrylates scaffolds. The structures of the prepared compounds were characterized by ¹H-NMR, ¹³C-NMR and electrospray ionization mass spectrometry (ESI-MS), and the bioactivity of the target compounds against twelve phytopathogenic fungi was investigated. The preliminary in vitro antifungal activity screening showed that most of the target compounds had moderate inhibition on various pathogenic fungi at the concentration of 100 mg·L⁻¹, and presented broad-spectrum antifungal activities. Further studies also indicated that compounds 7e and 7k still showed some inhibitory activity against Pestallozzia theae, Sclerotinia sclerotiorum and Gibberella zeae on rape plants at lower concentrations, which could be optimized as a secondary lead for further research.

Transition Metal-Free Intermolecular C(sp2)-H Direct Amination of Furanones via a Redox Pathway

A direct C(sp²)-H amination of 2-furanones under metal-free conditions was realized. This unprecedented intermolecular C-H to C-N conversion provides rapid access to 4-amino-furanone derivatives and novel aza-heterocycle fused furanone skeletons. A redox mechanism based on a double-Michael-addition intermediate INT2 is proposed and detected by spectrometry.

New molecular insights into the tyrosyl-tRNA synthase inhibitors: CoMFA, CoMSIA analyses and molecular docking studies

Drug resistance caused by excessive and indiscriminate antibiotic usage has become a serious public health problem. The need of finding new antibacterial drugs is more urgent than ever before. Tyrosyl-tRNA synthase was proved to be a potent target in combating drug-resistant bacteria. In silico methodologies including molecular docking and 3D-QSAR were employed to investigate a series of newly reported tyrosyl-tRNA synthase inhibitors of furanone derivatives. Both internal and external cross-validation were conducted to obtain high predictive and satisfactory CoMFA model (q 2 = 0.611, r 2pred  = 0.933, r 2m  = 0.954) and CoMSIA model (q 2 = 0.546, r 2pred  = 0.959, r 2m  = 0.923). Docking results, which correspond with CoMFA/CoMSIA contour maps, gave the information for interactive mode exploration. Ten new molecules designed on the basis of QSAR and docking models have been predicted more potent than the most active compound 3-(4-hydroxyphenyl)-4-(2-morpholinoethoxy)furan-2(5H)-one (15) in the literatures. The results expand our understanding of furanones as inhibitors of tyrosyl-tRNA synthase and could be helpful in rationally designing of new analogs with more potent inhibitory activities.

Dihydropyrazoles containing morpholine: design, synthesis and bioassay testing as potent antimicrobial agents

A series of dihydropyrazole derivatives were designed and synthesized as antimicrobial agents. In both docking simulation and bioassay tests, these compounds showed potent S. aureus TyrRS enzyme inhibition activity.

Novel 3-arylfuran-2(5H)-one-fluoroquinolone hybrid: design, synthesis and evaluation as antibacterial agent

3-Arylfuran-2(5H)-one, a novel antibacterial pharmacophore targeting tyrosyl-tRNA synthetase (TyrRS), was hybridized with the clinically used fluoroquinolones to give a series of novel multi-target antimicrobial agents. Thus, twenty seven 3-arylfuran-2(5H)-one-fluoroquinolone hybrids were synthesized and evaluated for their antimicrobial activities. Some of the hybrids exhibited merits from both parents, displaying a broad spectrum of activity against resistant strains including both Gram-negative and Gram-positive bacteria. The most potent compound (11) in antibacterial assay shows MIC50 of 0.11μg/mL against Multiple drug resistant Escherichia coli, being about 51-fold more potent than ciprofloxacin. The enzyme assays reveal that 11 is a potent multi-target inhibitor with IC50 of 1.15±0.07μM against DNA gyrase and 0.12±0.04μM against TyrRS, respectively. Its excellent inhibitory activities against isolated enzymes and intact cells strongly suggest that 11 deserves to further research as a novel antibiotic.

3-Aryl-4-acyloxyethoxyfuran-2(5H)-ones as inhibitors of tyrosyl-tRNA synthetase: synthesis, molecular docking and antibacterial evaluation

Thirty-eight 3-aryl-4-acyloxyethoxyfuran-2(5H)-ones were designed, prepared and tested for antibacterial activities. Some of them showed significant antibacterial activity against Gram-positive organism, Gram-negative organism and fungus. Out of these compounds, 4-(2-(3-chlorophenylformyloxy)ethoxy)-3-(4-chlorophenyl)furan-2(5H)-one (d40) showed the widest spectrum of activity with MIC50 of 2.0μg/mL against Staphylococcus aureus, 4.3μg/mL against Escherichia coli, 1.5μg/mL against Pseudomonas aeruginosa and 1.2μg/mL against Candida albicans. Our data disclosed that MIC50 values against whole cell bacteria are positive correlation with MIC50 values against tyrosyl-tRNA synthetase. Meanwhile, molecular docking of d40 into S. aureus tyrosyl-tRNA synthetase active site was also performed, and the inhibitor tightly fitting the active site might be an important reason why it has high antimicrobial activity.

3-(4-Bromo-phen-yl)-4-[2-(4-nitro-phen-yl)hydrazin-yl]furan-2(5H)-one

In the title compound, C₁₆H₁₂BrN₃O₄, the furan-2(5H)-one ring forms a dihedral angle of 33.19 (9)° with the 4-bromo­benzene unit and is nearly perpendicular to the 4-nitro­benzene segment, making a dihedral angle of 89.93 (10)°. In the crystal, N—H⋯O hydrogen bonds link the mol­ecules, generating an infinite chain along [010]. The chains are linked into a three-dimensional network by C—H⋯O, C—H⋯π and π–π contacts [centroid–centroid separation = 3.805 (2) Å].

3-(4-Bromo-phen-yl)-4-(4-hy-droxy-anilino)furan-2(5H)-one

In the title compound, C₁₆H₁₂BrNO₃, the butyrolactone core adopts the furan-2(5H)-one structure and forms dihedral angles of 44.80 (17) and 65.73 (18)° with the bromo­benzene and phenol rings, respectively. In the crystal, N—H⋯O and O—H⋯O hydrogen bonds link the mol­ecules, generating R₄³(26) loops The edge-fused rings extend to form a chain running along the b-axis direction and C—H⋯π contacts help to consolidate the packing.