Structure-activity relationships and optimization of 3,5-dichloropyridine derivatives as novel P2X(7) receptor antagonists

J Med Chem. 2012 Apr 26;55(8):3687-98. doi: 10.1021/jm2012326. Epub 2012 Apr 6.


Screening of a library of chemical compounds showed that the dichloropyridine-based analogue 9 was a novel P2X(7) receptor antagonist. To optimize its activity, we assessed the structure-activity relationships (SAR) of 9, focusing on the hydrazide linker, the dichloropyridine skeleton, and the hydrophobic acyl (R(2)) group. We found that the hydrazide linker and the 3,5-disubstituted chlorides in the pyridine skeleton were critical for P2X(7) antagonistic activity and that the presence of hydrophobic polycycloalkyl groups at the R(2) position optimized antagonistic activity. In the EtBr uptake assay in hP2X(7)-expressing HEK293 cells, the optimized antagonists, 51 and 52, had IC(50) values of 4.9 and 13 nM, respectively. The antagonistic effects of 51 and 52 were paralleled by their ability to inhibit the release of the pro-inflammatory cytokine, IL-1β, by LPS/IFN-γ/BzATP stimulation of THP-1 cells (IC(50) = 1.3 and 9.2 nM, respectively). In addition, 52 strongly inhibited iNOS/COX-2 expression and NO production in THP-1 cells, further indicating that this compound blocks inflammatory signaling and suggesting that the dichloropyridine analogues may be useful in developing P2X(7) receptor targeted anti-inflammatory agents.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line, Tumor
  • Cyclooxygenase 2 / biosynthesis
  • HEK293 Cells
  • Humans
  • Interleukin-18 / antagonists & inhibitors
  • Interleukin-18 / metabolism
  • Nitric Oxide Synthase Type II / biosynthesis
  • Purinergic P2X Receptor Antagonists / chemistry*
  • Pyridazines / chemistry
  • Pyridazines / pharmacology
  • Pyridines / chemistry
  • Pyridines / pharmacology*
  • Receptors, Purinergic P2X7 / drug effects*
  • Structure-Activity Relationship


  • Interleukin-18
  • Purinergic P2X Receptor Antagonists
  • Pyridazines
  • Pyridines
  • Receptors, Purinergic P2X7
  • NOS2 protein, human
  • Nitric Oxide Synthase Type II
  • Cyclooxygenase 2
  • PTGS2 protein, human