title: Discovery and analysis of 4H-pyridopyrimidines, a class of selective bacterial protein synthesis inhibitors.
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 (IC(50)s) 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.
authors.affiliation: Chemistry Department, The University of Texas-Pan American, 1201 W. University Drive, Edinburg, TX 78541, USA.
authors.forename: Wendy
authors.initials: W
authors.lastname: Ribble
authors.forename: Walter E
authors.initials: WE
authors.lastname: Hill
authors.forename: Urs A
authors.initials: UA
authors.lastname: Ochsner
authors.forename: Thale C
authors.initials: TC
authors.lastname: Jarvis
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Guiles
authors.forename: Nebojsa
authors.initials: N
authors.lastname: Janjic
authors.forename: James M
authors.initials: JM
authors.lastname: Bullard
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects; D006193:Haemophilus influenzae / Q000187:drug effects; D020128:Inhibitory Concentration 50; D008826:Microbial Sensitivity Tests; D001936:Moraxella catarrhalis / Q000187:drug effects; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D011743:Pyrimidines / Q000494:pharmacology*; D013211:Staphylococcus aureus / Q000187:drug effects; D013296:Streptococcus pneumoniae / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D011500:Protein Synthesis Inhibitors; D011743:Pyrimidines