The identification and characterization of hydrazinyl urea-based antibacterial agents through combinatorial chemistry

Improved small-molecule macroarray platform for the rapid synthesis and discovery of antibacterial chalcones

Bacterial resistance to current antibiotics is a major global health threat. Consequently, there is an urgent need for the identification of new antibacterial agents. We are applying the small-molecule macroarray platform to rapidly synthesize and screen compounds for activity against methicillin-resistant Staphylococcus aureus (MRSA). Herein, we report the synthesis of a 1,3-diphenyl-2-propen-1-one (chalcone) macroarray using a Rink-amide linker-derivatized cellulose support. The Rink linker allowed for the incorporation of a broader array of library building blocks relative to our previous syntheses because milder reaction conditions could be utilized; significantly higher compound loadings were also achieved (~80% vs ~15%). Analysis of the 174-member chalcone macroarray in off-support antibacterial screening assays revealed three chalcones with minimum inhibitory concentration (MIC) values against MRSA comparable to currently used antibacterial drugs and low hemolytic activities. These results serve to further showcase and extend the utility of the small molecule macroarray for antibacterial discovery.

Novel benzothiazolyl urea and thiourea derivatives with potential cytotoxic and antimicrobial activities

A novel series of benzothiazole urea and thiourea derivatives was synthesized and evaluated for its in vitro cytotoxicity against MCF-7 breast cancer cells. The N1-(benzothiazol-2-yl)-N3-morpholinourea 3 displayed the highest cytotoxic activity in this series. A docked pose of 3 was obtained bound to G-quadruplex of human telomere DNA active site using the Molecular Operating Environment (MOE) module. Moreover, the synthesized compounds were screened for their antimicrobial activity against Mycobacterium tuberculosis H37Rv, E. coli, S. aureus and C. albicans. Again, 3 showed the best activity against M. tuberculosis H37Rv while other compounds were equipotent with ampicillin against S. aureus and E. coli.

Aryl urea analogs with broad-spectrum antibacterial activity

The preparation and evaluation of novel aryl urea analogs as broad-spectrum antibacterial agents is described. Numerous compounds showed low micromolar minimum inhibitory concentrations (MIC) against both Gram-positive and Gram-negative bacteria. Selected analogs also exhibited in vivo efficacy in a lethal murine model of bacterial septicemia.

Novel inhibitors of bacterial cell wall synthesis

Over the past forty years, efforts to discover antibacterials have yielded a wide variety of chemical structures, almost exclusively natural products, which inhibit many steps in cell wall synthesis. Although screening for new cell wall inhibitors has been continuous during that period, there have been few reports of new drugs. With the advent of genomics, high resolution X-ray crystallography and the recognition of the need for new antibiotics to combat resistant organisms, there has been a resurgence in interest in this validated target area.

Lead compounds discovered from libraries: part 2

Many lead compounds with the potential to progress to viable drug candidates have been identified from libraries during the past two years. There are two key strategies most often employed to find leads from libraries: first, high-throughput biological screening of corporate compound collections; and second, synthesis and screening of project-directed libraries (i.e. target-based libraries). Numerous success stories, including the discovery of several clinical candidates, testify to the utility of chemical library collections as proven sources of new leads for drug development.

Combinatorial chemistry in anti-infectives research

The ever-increasing resistance to current anti-infective drugs has become a major concern to the medical community. As a result, research efforts have been stepped up with the ultimate goal to provide new, more effective and safer antimicrobial treatments that will overcome the resistance problem. In this context, advances in molecular biology, automation and combinatorial chemistry will play a crucial role in the timely introduction of these products onto the market. How the application of combinatorial techniques can impact anti-infectives research will be reviewed using illustrative examples.