Ascorbic acid modulates the structure of the virulence factor pyocyanin and ascorbic acid-furanone-30 combination facilitate biofilm disruption.

The production of pyocyanin by increases its virulence, fitness and biofilm formation. Pyocyanin is also a redox molecule and we hypothesize that ascorbic acid being an antioxidant will interact with pyocyanin. The main objective of this study was to investigate the potential interaction of ascorbic acid with pyocyanin, and also to investigate the impact of ascorbic acid in combination with Furanone-30 on quorum sensing and biofilm formation of .

Synthesis of Novel Quinazolinone Analogues for Quorum Sensing Inhibition.

As bacteria continue to develop resistance mechanisms against antimicrobials, an alternative method to tackle this global concern must be developed. As the system is the most well-known and responsible for biofilm and pyocyanin production, quinazolinone inhibitors of the system in were developed. Molecular docking following a rationalised medicinal chemistry approach was adopted to design these analogues.

Novel quinazolinone disulfide analogues as pqs quorum sensing inhibitors against Pseudomonas aeruginosa.

It is well established that the quorum sensing (QS) in Pseudomonas aeruginosa is primarily responsible for the synthesis and the release of several virulence factors including pyocyanin and are involved in biofilm formation. In the Pseudomonas quinolone signal (PQS) system, autoinducers such as PQS and HHQ bind and activate the transcription regulator protein receptor PqsR (MvfR). Targeting PqsR with competitive inhibitors could be a promising strategy to inhibit QS in P.

Halogenated Dihydropyrrol-2-One Molecules Inhibit Pyocyanin Biosynthesis by Blocking the Quinolone Signaling System.

Quorum-sensing (QS) systems of  are involved in the control of biofilm formation and virulence factor production. The current study evaluated the ability of halogenated and a non-halogenated version (4d) to inhibit the QS receptor proteins LasR and PqsR. The DHP molecules exhibited concentration-dependent inhibition of LasR and PqsR receptor proteins.

Synthesis of Alkyne-Substituted Dihydropyrrolones as Bacterial Quorum-Sensing Inhibitors of .

The Quorum-sensing system in is responsible for the pathogenicity and the production of virulence factors and biofilm formation. Dihydropyrrolones were previously found to act as inhibitors of QS-dependent bacterial phenotypes. In this study, a range of dihydropyrrolone (DHP) analogues was synthesized via the lactone-lactam conversion of lactone intermediates followed by the formation of novel acetylene analogues of dihydropyrrolones from brominated dihydropyrrolones via Sonogashira coupling reactions in moderate to high yields.

Natural Product Rottlerin Derivatives Targeting Quorum Sensing.

Rottlerin is a natural product consisting of chalcone and flavonoid scaffolds, both of which have previously shown quorum sensing (QS) inhibition in various bacteria. Therefore, the unique rottlerin scaffold highlights great potential in inhibiting the QS system of Rottlerin analogues were synthesised by modifications at its chalcone- and methylene-bridged acetophenone moieties. The synthesis of analogues was achieved using an established five-step synthetic strategy for chalcone derivatives and utilising the Mannich reaction at C6 of the chromene to construct morpholine analogues.

Novel Seleno- and Thio-Urea Containing Dihydropyrrol-2-One Analogues as Antibacterial Agents.

The quorum sensing (QS) system in multi-drug-resistant bacteria such as is primarily responsible for the development of antibiotic resistance and is considered an attractive target for antimicrobial drug discovery. In this study, we synthesised a series of novel selenourea and thiourea-containing dihydropyrrol-2-one (DHP) analogues as LasR antagonists. The selenium DHP derivatives displayed significantly better quorum-sensing inhibition (QSI) activities than the corresponding sulphur analogues.

Thioether-linked dihydropyrrol-2-one analogues as PqsR antagonists against antibiotic resistant Pseudomonas aeruginosa.

The Pseudomonas quinolone system (pqs) is one of the key quorum sensing systems in antibiotic-resistant P. aeruginosa and is responsible for the production of virulence factors and biofilm formation. Thus, synthetic small molecules that can target the PqsR (MvfR) receptor can be utilized as quorum sensing inhibitors to treat P.

Design, Synthesis and Biological Evaluation of Novel Anthraniloyl-AMP Mimics as PQS Biosynthesis Inhibitors Against Resistance.

The quinolone system (PQS) is one of the three major interconnected quorum sensing signaling systems in . The virulence factors PQS and HHQ activate the transcription regulator PqsR (MvfR), which controls several activities in bacteria, including biofilm formation and upregulation of PQS biosynthesis. The enzyme anthraniloyl-CoA synthetase (PqsA) catalyzes the first and critical step in the biosynthesis of quinolones; therefore, it is an attractive target for the development of anti-virulence therapeutics against resistance.

Direct N-H/ N-Me Aziridination of Unactivated Olefins Using O-(Sulfonyl)hydroxylamines as Aminating Agents.

Unactivated aziridines are the core substructures in a plethora of bioactive natural products and serve as building blocks in organic synthesis. Despite this, very limited methods are available to access them directly from olefins, as most of the known methods are devoted to their activated counterparts. Herein, we have developed a highly efficient Rh(II)-catalyzed method for the direct preparation of unactivated aziridines from olefins using O-(sulfonyl)hydroxylamines as the aminating agent.

O-Substituted hydroxyl amine reagents: an overview of recent synthetic advances.

Reagents derived from hydroxylamines such as 2,4-dinitrophenylhydroxylamine (DPH), O-(diphenylphosphinyl)hydroxylamine (DPPH), hydroxylamine-O-sulfonic acid (HOSA) and other related reagents in which oxygen is substituted with good leaving groups recently showed remarkable potential as electrophilic aminating agents and as a source of the amino group. They facilitate stereo- and regioselective C-N, N-N, O-N, and S-N bond-formation reactions and intra-molecular cyclizations without the requirement of expensive metal catalysts. In this review we have discussed the important transformations achieved with these reagents.