Can We Make Small Molecules Lean? Optimization of a Highly Lipophilic TarO Inhibitor

J Med Chem. 2017 May 11;60(9):3851-3865. doi: 10.1021/acs.jmedchem.7b00113. Epub 2017 Mar 29.

Abstract

We describe our optimization efforts to improve the physicochemical properties, solubility, and off-target profile of 1, an inhibitor of TarO, an early stage enzyme in the biosynthetic pathway for wall teichoic acid (WTA) synthesis. Compound 1 displayed a TarO IC50 of 125 nM in an enzyme assay and possessed very high lipophilicity (clogP = 7.1) with no measurable solubility in PBS buffer. Structure-activity relationship (SAR) studies resulted in a series of compounds with improved lipophilic ligand efficiency (LLE) consistent with the reduction of clogP. From these efforts, analog 9 was selected for our initial in vivo study, which in combination with subefficacious dose of imipenem (IPM) robustly lowered the bacterial burden in a neutropenic Staphylococci murine infection model. Concurrent with our in vivo optimization effort using 9, we further improved LLE as exemplified by a much more druglike analog 26.

MeSH terms

  • Animals
  • Female
  • Lipids / chemistry*
  • Methicillin-Resistant Staphylococcus aureus / drug effects
  • Methicillin-Resistant Staphylococcus aureus / growth & development
  • Mice
  • Mice, Inbred BALB C
  • Microbial Sensitivity Tests
  • Small Molecule Libraries*
  • Solubility
  • Structure-Activity Relationship

Substances

  • Lipids
  • Small Molecule Libraries