Antibacterial Spiropyrimidinetriones with N-Linked Azole Substituents on a Benzisoxazole Scaffold Targeting DNA Gyrase.

Herein, we report spiropyrimidinetriones (SPTs) incorporating N-linked azole substituents on a benzisoxazole scaffold with improved Gram-positive antibacterial activity relative to previously described analogues. SPTs have an unusual spirocyclic architecture and represent a new antibacterial class of bacterial DNA gyrase and topoisomerase IV inhibitors. They are not cross-resistant to fluoroquinolones and other DNA gyrase/topoisomerase IV inhibitors used clinically.

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.

Pharmacodynamic Profiling of a Siderophore-Conjugated Monocarbam in Pseudomonas aeruginosa: Assessing the Risk for Resistance and Attenuated Efficacy.

The objective of this study was to investigate the risk of attenuated efficacy due to adaptive resistance for the siderophore-conjugated monocarbam SMC-3176 in Pseudomonas aeruginosa by using a pharmacokinetic/pharmacodynamic (PK/PD) approach. MICs were determined in cation-adjusted Mueller-Hinton broth (MHB) and in Chelex-treated, dialyzed MHB (CDMHB). Spontaneous resistance was assessed at 2× to 16× the MIC and the resulting mutants sequenced.

Responding to the challenge of untreatable gonorrhea: ETX0914, a first-in-class agent with a distinct mechanism-of-action against bacterial Type II topoisomerases.

With the diminishing effectiveness of current antibacterial therapies, it is critically important to discover agents that operate by a mechanism that circumvents existing resistance. ETX0914, the first of a new class of antibacterial agent targeted for the treatment of gonorrhea, operates by a novel mode-of-inhibition against bacterial type II topoisomerases. Incorporating an oxazolidinone on the scaffold mitigated toxicological issues often seen with topoisomerase inhibitors.

Discovery of Novel DNA Gyrase Inhibiting Spiropyrimidinetriones: Benzisoxazole Fusion with N-Linked Oxazolidinone Substituents Leading to a Clinical Candidate (ETX0914).

A novel class of bacterial type-II topoisomerase inhibitor displaying a spiropyrimidinetrione architecture fused to a benzisoxazole scaffold shows potent activity against Gram-positive and fastidious Gram-negative bacteria. Here, we describe a series of N-linked oxazolidinone substituents on the benzisoxazole that improve upon the antibacterial activity of initially described compounds of the class, show favorable PK properties, and demonstrate efficacy in an in vivo Staphylococcus aureus infection model. Inhibition of the topoisomerases DNA gyrase and topoisomerase IV from both Gram-positive and a Gram-negative organisms was demonstrated.

Insights into the mechanism of inhibition of novel bacterial topoisomerase inhibitors from characterization of resistant mutants of Staphylococcus aureus.

The type II topoisomerases DNA gyrase and topoisomerase IV are clinically validated bacterial targets that catalyze the modulation of DNA topology that is vital to DNA replication, repair, and decatenation. Increasing resistance to fluoroquinolones, which trap the topoisomerase-DNA complex, has led to significant efforts in the discovery of novel inhibitors of these targets. AZ6142 is a member of the class of novel bacterial topoisomerase inhibitors (NBTIs) that utilizes a distinct mechanism to trap the protein-DNA complex.

Pyridodiazepine amines are selective therapeutic agents for helicobacter pylori by suppressing growth through inhibition of glutamate racemase but are predicted to require continuous elevated levels in plasma to achieve clinical efficacy.

A pyridodiazepine amine inhibitor of Helicobacter pylori glutamate racemase (MurI) was characterized. The compound was selectively active against H. pylori, and growth suppression was shown to be mediated through the inhibition of MurI by several methods.

Characterization of the novel DNA gyrase inhibitor AZD0914: low resistance potential and lack of cross-resistance in Neisseria gonorrhoeae.

The unmet medical need for novel intervention strategies to treat Neisseria gonorrhoeae infections is significant and increasing, as rapidly emerging resistance in this pathogen is threatening to eliminate the currently available treatment options. AZD0914 is a novel bacterial gyrase inhibitor that possesses potent in vitro activities against isolates with high-level resistance to ciprofloxacin and extended-spectrum cephalosporins, and it is currently in clinical development for the treatment of N. gonorrhoeae infections.

In vitro antibacterial activity of AZD0914, a new spiropyrimidinetrione DNA gyrase/topoisomerase inhibitor with potent activity against Gram-positive, fastidious Gram-Negative, and atypical bacteria.

AZD0914 is a new spiropyrimidinetrione bacterial DNA gyrase/topoisomerase inhibitor with potent in vitro antibacterial activity against key Gram-positive (Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, Streptococcus pyogenes, and Streptococcus agalactiae), fastidious Gram-negative (Haemophilus influenzae and Neisseria gonorrhoeae), atypical (Legionella pneumophila), and anaerobic (Clostridium difficile) bacterial species, including isolates with known resistance to fluoroquinolones. AZD0914 works via inhibition of DNA biosynthesis and accumulation of double-strand cleavages; this mechanism of inhibition differs from those of other marketed antibacterial compounds. AZD0914 stabilizes and arrests the cleaved covalent complex of gyrase with double-strand broken DNA under permissive conditions and thus blocks religation of the double-strand cleaved DNA to form fused circular DNA.

Novel DNA gyrase inhibiting spiropyrimidinetriones with a benzisoxazole scaffold: SAR and in vivo characterization.

The compounds described herein with a spirocyclic architecture fused to a benzisoxazole ring represent a new class of antibacterial agents that operate by inhibition of DNA gyrase as corroborated in an enzyme assay and by the inhibition of precursor thymidine into DNA during cell growth. Activity resided in the configurationally lowest energy (2S,4R,4aR) diastereomer. Highly active compounds against Staphylococcus aureus had sufficiently high solubility, high plasma protein free fraction, and favorable pharmacokinetics to suggest that in vivo efficacy could be demonstrated, which was realized with compound (-)-1 in 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.

Exploring the UDP pocket of LpxC through amino acid analogs.

Lipopolysaccharide (LPS) biosynthesis is an attractive antibacterial target as it is both conserved and essential for the survival of key pathogenic bacteria. Lipid A is the hydrophobic anchor for LPS and a key structural component of the outer membrane of Gram-negative bacteria. Lipid A biosynthesis is performed in part by a unique zinc dependent metalloamidase, LpxC (UDP-3-O-(R-3-hydroxymyristoyl)-N-acetylglucosamine deacetylase), which catalyzes the first non-reversible step in lipid A biosynthesis.

In vivo validation of thymidylate kinase (TMK) with a rationally designed, selective antibacterial compound.

There is an urgent need for new antibacterials that pinpoint novel targets and thereby avoid existing resistance mechanisms. We have created novel synthetic antibacterials through structure-based drug design that specifically target bacterial thymidylate kinase (TMK), a nucleotide kinase essential in the DNA synthesis pathway. A high-resolution structure shows compound TK-666 binding partly in the thymidine monophosphate substrate site, but also forming new induced-fit interactions that give picomolar affinity.

Compound efflux in Helicobacter pylori.

Susceptibility testing with a variety of structurally unrelated compounds showed that hefC in Helicobacter pylori is involved in multidrug efflux. This efflux was shown to depend on the proton motive force, as demonstrated by ethidium bromide accumulation experiments. Thus, H.