Development of 4H-pyridopyrimidines: a class of selective bacterial protein synthesis inhibitors

ABSTRACT A method was developed to determine the contributions of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) to the nitrification potentials (NPs) of soils taken from forest, pasture, cropped, and fallowed (19 years) lands. Soil slurries were exposed to acetylene to irreversibly inactivate ammonia monooxygenase, and upon the removal of acetylene, the recovery of nitrification potential (RNP) was monitored in the presence and absence of bacterial or eukaryotic protein synthesis inhibitors. For unknown reasons, and despite measureable NPs, RNP did not occur consistently in forest soil samples; however, pasture, cropped, and fallowed soil RNPs commenced after lags that ranged from 12 to 30 h after acetylene removal. Cropped soil RNP was completely prevented by the bacterial protein synthesis inhibitor kanamycin (800 μg/ml), whereas a combination of kanamycin plus gentamicin (800 μg/ml each) only partially prevented the RNP (60%) of fallowed soils. Pasture soil RNP was completely insensitive to either kanamycin, gentamicin, or a combination of the two. Unlike cropped soil, pasture and fallowed soil RNPs occurred at both 30Ã¯Â¿Â½C and 40Ã¯Â¿Â½C and without supplemental NH4 + (≤10 μM NH4 + in solution), and pasture soil RNP demonstrated ∼50% insensitivity to 100 μM allyl thiourea (ATU). In addition, fallowed and pasture soil RNPs were insensitive to the fungal inhibitors nystatin and azoxystrobin. This combination of properties suggests that neither fungi nor AOB contributed to pasture soil RNP and that AOA were responsible for the RNP of the pasture soils. Both AOA and AOB may contribute to RNP in fallowed soil, while RNP in cropped soils was dominated by AOB.

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Discovery and Analysis of 4H-Pyridopyrimidines, a Class of Selective Bacterial Protein Synthesis Inhibitors

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00638-10 ◽

2010 ◽

Vol 54 (11) ◽

pp. 4648-4657 ◽

Cited By ~ 18

Author(s):

Wendy Ribble ◽

Walter E. Hill ◽

Urs A. Ochsner ◽

Thale C. Jarvis ◽

Joseph W. Guiles ◽

...

Keyword(s):

Protein Synthesis ◽

High Throughput Screening ◽

Bacterial Protein ◽

Protein Synthesis Inhibitors ◽

Macromolecular Synthesis ◽

Chemical Library ◽

Trna Synthetases ◽

E Coli ◽

Bacterial Protein Synthesis ◽

Protein Synthesis System

ABSTRACT Bacterial protein synthesis is the target for numerous natural and synthetic antibacterial agents. We have developed a poly(U) mRNA-directed aminoacylation/translation protein synthesis system composed of phenyl-tRNA synthetases, ribosomes, and ribosomal factors from Escherichia coli. This system, utilizing purified components, has been used for high-throughput screening of a small-molecule chemical library. We have identified a series of compounds that inhibit protein synthesis with 50% inhibitory concentrations (IC50s) ranging from 3 to 14 μM. This series of compounds all contained the same central scaffold composed of tetrahydropyrido[4,3-d]pyrimidin-4-ol (e.g., 4H-pyridopyrimidine). All analogs contained an ortho pyridine ring attached to the central scaffold in the 2 position and either a five- or a six-member ring tethered to the 6-methylene nitrogen atom of the central scaffold. These compounds inhibited the growth of E. coli, Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis, with MICs ranging from 0.25 to 32 μg/ml. Macromolecular synthesis (MMS) assays with E. coli and S. aureus confirmed that antibacterial activity resulted from specific inhibition of protein synthesis. Assays were developed for the steps performed by each component of the system in order to ascertain the target of the compounds, and the ribosome was found to be the site of inhibition.

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Structure‐activity optimization of 4H‐pyridopyrimidines: a class of selective bacterial protein synthesis inhibitors

The FASEB Journal ◽

10.1096/fasebj.25.1_supplement.967.1 ◽

2011 ◽

Vol 25 (S1) ◽

Author(s):

James M Bullard ◽

Joseph W. Guiles ◽

Andras Toro ◽

Urs Ochsner

Keyword(s):

Protein Synthesis ◽

Bacterial Protein ◽

Protein Synthesis Inhibitors ◽

Structure Activity ◽

Bacterial Protein Synthesis ◽

Activity Optimization

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Modulation of Release of Proinflammatory Bacterial Compounds by Antibacterials: Potential Impact on Course of Inflammation and Outcome in Sepsis and Meningitis

Clinical Microbiology Reviews ◽

10.1128/cmr.15.1.95-110.2002 ◽

2002 ◽

Vol 15 (1) ◽

pp. 95-110 ◽

Cited By ~ 159

Author(s):

Roland Nau ◽

Helmut Eiffert

Keyword(s):

Protein Synthesis ◽

Bacterial Load ◽

Animal Experiments ◽

Sufficient Evidence ◽

Bacterial Protein ◽

Protein Synthesis Inhibitors ◽

Number Of Patients ◽

Bacterial Protein Synthesis

SUMMARY Several bacterial components (endotoxin, teichoic and lipoteichoic acids, peptidoglycan, DNA, and others) can induce or enhance inflammation and may be directly toxic for eukaryotic cells. Bactericidal antibiotics which inhibit bacterial protein synthesis release smaller quantities of proinflammatory/toxic bacterial compounds than Β-lactams and other cell wall-active drugs. Among the Β-lactams, compounds binding to penicillin-binding protein 2 (PBP-2) release smaller amounts of bacterial substances than antibacterials inhibiting PBP-3. Generally, high antibiotic concentrations (more than 10 times the MIC) induce the release of fewer bacterial proinflammatory/toxic compounds than concentrations close to the MIC. In several in vitro and in vivo systems, bacteria treated with protein synthesis inhibitors or Β-lactams inhibiting PBP-2 induce less inflammation than bacteria treated with PBP-3-active Β-lactams. In mouse models of Escherichia coli peritonitis sepsis and of Streptococcus pneumoniae meningitis, lower release of proinflammatory bacterial compounds was associated with reduced mortality. In conclusion, sufficient evidence for the validity of the concept of modulating the release of proinflammatory bacterial compounds by antibacterials has been accumulated in vitro and in animal experiments to justify clinical trials in sepsis and meningitis. A properly conducted study addressing the potential benefit of bacterial protein synthesis inhibitors versus Β-lactam antibiotics will require both strict selection and inclusion of a large number of patients. The benefit of this approach should be greatest in patients with a high bacterial load.

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