Negishi cross-coupling enabled synthesis of novel NAD(+)-dependent DNA ligase inhibitors and SAR development.

Two novel compounds, pyridopyrimidines (1) and naphthyridines (2) were identified as potent inhibitors of bacterial NAD(+)-dependent DNA ligase (Lig) A in a fragment screening. SAR was guided by molecular modeling and X-ray crystallography. It was observed that the diaminonitrile pharmacophore made a key interaction with the ligase enzyme, specifically residues Glu114, Lys291, and Leu117.

Characterization of novel respiratory syncytial virus inhibitors identified by high throughput screen.

Respiratory Syncytial Virus (RSV) is a major cause of lower respiratory tract infections with no effective treatment available. Finding novel inhibitors of RSV is an important first step towards developing an efficacious RSV therapy. Here we report the characterization of three novel classes of RSV replication inhibitors identified through a high throughput RSV replicon screen of ∼1million compounds in the AstraZeneca compound collection.

The role of a novel auxiliary pocket in bacterial phenylalanyl-tRNA synthetase druggability.

The antimicrobial activity of phenyl-thiazolylurea-sulfonamides against Staphylococcus aureus PheRS are dependent upon phenylalanine levels in the extracellular fluids. Inhibitor efficacy in animal models of infection is substantially diminished by dietary phenylalanine intake, thereby reducing the perceived clinical utility of this inhibitor class. The search for novel antibacterial compounds against Gram-negative pathogens led to a re-evaluation of this phenomenon, which is shown here to be unique to S.

Discovery of inhibitors of 4'-phosphopantetheine adenylyltransferase (PPAT) to validate PPAT as a target for antibacterial therapy.

Inhibitors of 4'-phosphopantetheine adenylyltransferase (PPAT) were identified through high-throughput screening of the AstraZeneca compound library. One series, cycloalkyl pyrimidines, showed inhibition of PPAT isozymes from several species, with the most potent inhibition of enzymes from Gram-positive species. Mode-of-inhibition studies with Streptococcus pneumoniae and Staphylococcus aureus PPAT demonstrated representatives of this series to be reversible inhibitors competitive with phosphopantetheine and uncompetitive with ATP, binding to the enzyme-ATP complex.

Antimicrobial Activity of Adenine-Based Inhibitors of NAD(+)-Dependent DNA Ligase.

The relationship between enzyme inhibition and antimicrobial potency of adenine-based NAD(+)-dependent DNA ligase (LigA) inhibitors was investigated using a strain of the Gram-negative pathogen Haemophilus influenzae lacking its major AcrAB-TolC efflux pump and the Gram-positive pathogen Streptococcus pneumoniae. To this end, biochemical inhibitors not mediating their antibacterial mode of action (MOA) via LigA were removed from the analysis. In doing so, a significant number of compounds were identified that acted via inhibition of LigA in S.

Novel rapidly diversifiable antimicrobial RNA polymerase switch region inhibitors with confirmed mode of action in Haemophilus influenzae.

A series of inhibitors with a squaramide core was synthesized following its discovery in a high-throughput screen for novel inhibitors of a transcription-coupled translation assay using Escherichia coli S30 extracts. The inhibitors were inactive when the plasmid substrate was replaced with mRNA, suggesting they interfered with transcription. This was confirmed by their inhibition of purified E.

Array synthesis of novel lipodepsipeptide.

Synthetic array technology was utilized to rapidly synthesize and analyze a diverse set of reductive alkylation analogues of daptomycin. Analysis of the array suggested the use of polar functionality such as sulfonamides or amide or polar spaces such as piperazine would beneficially affect activity.

Synthesis and biological activity of N-Acylated ornithine analogues of daptomycin.

N-Acylated ornithine analogues of daptomycin were synthesized and tested for their antibacterial efficacy.

In vitro bactericidal activities of daptomycin against Staphylococcus aureus and Enterococcus faecalis are not mediated by inhibition of lipoteichoic acid biosynthesis.

Previous studies have suggested that lipoteichoic acid biosynthesis inhibition is the mechanism of action of daptomycin. In this investigation, daptomycin inhibited all macromolecular synthesis in Staphylococcus aureus, Enterococcus faecalis, and Enterococcus hirae without kinetic or dose specificity for lipoteichoic acid. Daptomycin remained bactericidal in the absence of ongoing lipoteichoic acid synthesis.