Search

With the increasing antibiotic resistance of bacterial strains, alternative methods for infection control are in high demand. Quorum sensing (QS) is the bacterial communication system based on small molecules. QS is enables bacterial biofilm formation and pathogenic development. The interruption of QS has become a target for drug discovery, but remains in the early experimental phase. In this study, we synthesized a set of six compounds based on a scaffold (alkyl-quinoxalin-2(1 H )-one), new in the anti-QS of Gram-negative bacteria Aeromonas caviae Sch3. By quantifying biofilm formation, we were able to monitor the effect of these compounds from concentrations of 1 to 100 µM. Significant reduction in biofilm formation was achieved by 3-hexylylquinoxalin-2(1 H )-one ( 11 ), 3-hexylylquinoxalin-2(1 H )-one-6-carboxylic acid ( 12 ), and 3-heptylylquinoxalin-2(1 H )-one-6-carboxylic acid ( 14 ), ranging from 11% to 59% inhibition of the biofilm. This pilot study contributes to the development of anti-QS compounds to overcome the clinical challenge of resistant bacteria strains.

In this investigation, we searched for novel MAO-A inhibitors using a 3-benzylquinoxaline scaffold based on our earlier findings. Series of N'-(3-benzylquinoxalin-2-yl)acetohydrazide, 4a, N'-(3-benzylquinoxalin-2-yl)benzohydrazide derivatives 4b-f, N'-[2-(3-benzyl-2-oxoquinoxalin-1(2H)-yl)acetyl]benzohydrazide derivatives 7a-d, (9H-fluoren-9-yl)methyl 1-[2-(2-(3-benzyl-2-oxoquinoxalin-1(2H)-yl)acetyl)-hydrazinyl]-2-ylcarbamate derivatives 8a-c, 2-(3-benzyl-2-oxoquinoxalin-1(2H)-yl)-N'-benzylidene acetohydrazide derivatives 9a-h, and ethyl 2-(3-benzyl-2-oxoquinoxalin-1(2H)-yl)acetate derivatives 10a-e were synthesized and evaluated in vitro as inhibitors of the two monoamine oxidase isoforms, MAO-A and MAO-B. Most of the compounds showed a selective MAO-A inhibitory activity in the nanomolar or low micromolar range. Compounds 4e and 9g were the most potent derivatives with high MAO-A selectivity and their molecular docking studies were performed in order to rationalize the obtained biological result., (Copyright © 2015 Elsevier Masson SAS. All rights reserved.)

• Photoinduced Rapid Chloropropylation of Quinoxalin-2(1H)-Ones with Cyclopropane and HCl. • SAS was used as the photocatalyst, HCl was used as the chlorine source. • This synthetic method provides a green and efficient way to realize the chloropropylation of quinoxalin-2(1H)-ones and afford a series of chlorinated quinoxalin-2(1H)-one derivatives in good to excellent yields with a high functional group tolerance and a broad substrate scope. Herein, a photoinduced three-component reaction of aryl cyclopropane, quinoxalin-2(1H)-ones and HCl has been developed to introduce chloroalkyl motifs into N -heteroarenes. This synthetic method provides a green and efficient way to realize the chloropropylation of quinoxalin-2(1H)-ones and afford a series of chlorinated quinoxalin-2(1H)-one derivatives in moderate to good yields with the broad functional-group tolerance. [Display omitted] [ABSTRACT FROM AUTHOR]

A convenient and efficient protocol for the synthesis of thetetrazolo[1,5‐a]quinoxalin‐4(5H)‐ones via copper‐catalyzed [3+2] cyclization of azidotrimethylsilane with quinoxalin‐2(1H)‐ones under mild conditions has been disclosed. This practical protocol is compatible with a variety of functional groups and provides an access to functionalized tetrazolo[1,5‐a]quinoxalin‐4(5H)‐ones from readily available and safe starting materials. [ABSTRACT FROM AUTHOR]

Quinoxalin-2(1H)-one and its derived 3-Benzylquinoxalin-2(1H)-one were synthesized and characterized by UV-visible spectroscopy. The changes displayed by the photophysical properties of these molecules in different solvents can be explained in terms of a sum of dielectric polarity and hydrogen bonding effects taking part in the stabilisation of the structure. 3-Benzylquinoxalin-2(1H)-one exhibits two fluorescence emission bands ( F and F ) in very polar solvents and one band ( F ) in low polar solvents. These bands are assigned on the basis of the absorption and emission solvent effect. The abnormal fluorescence ( F ) observed in very polar solvents is attributed to an intermolecular interaction between solute and solvent molecules in the excited state (exciplex formation). [ABSTRACT FROM AUTHOR]