Synthesis and structure-activity relationships of pyrazolodiazepine derivatives as human P2X7 receptor antagonists

Bioorg Med Chem Lett. 2009 Nov 1;19(21):6053-8. doi: 10.1016/j.bmcl.2009.09.053. Epub 2009 Sep 17.


Screening of library compounds has yielded pyrazolodiazepine derivatives with P2X7 receptor antagonist activity. To explore the structure-activity relationships (SAR) of these pyrazolodiazepines as human P2X7 receptor antagonists, derivatives were synthesized by substitutions at positions R2 and R3 of the pyrazolodiazepine skeleton. Using a 2'(3')-O-(4-benzoylbenzoyl)ATP (BzATP)-induced fluorescent ethidium uptake assay, the activities of these derivatives were tested in HEK-293 cells stably expressing human P2X7 receptors. Moreover, the effect of these derivatives was assessed by measuring their effect on IL-1beta release induced by BzATP-induced activation of differentiated THP-1 cells. A 2-phenethyl pyrazolodiazepine derivative with a 1-methyl-1H-3-indolyl group at position R2 had fivefold greater activity than the derivative with a 5-isoquinolinyl at R2. Moreover, a benzyl moiety at R3 had fivefold greater activity than a bicyclic moiety. The stereochemical effect at C-6 showed a preference for the (R)-isomer. Among the series of active derivatives, compound 23b, with a phenethyl group at R1, a 3-methyl indole at R2, and a benzyl at R3, exhibited activity similar to that of the positive control, KN-62, as shown by the inhibitory effects of IL-1beta release.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Inflammatory Agents / chemical synthesis*
  • Anti-Inflammatory Agents / chemistry
  • Anti-Inflammatory Agents / pharmacology
  • Cell Line
  • Ethidium / metabolism
  • Humans
  • Interleukin-1beta / metabolism
  • Purinergic P2 Receptor Antagonists*
  • Pyrazoles / chemical synthesis*
  • Pyrazoles / chemistry
  • Pyrazoles / pharmacology
  • Receptors, Purinergic P2 / metabolism
  • Receptors, Purinergic P2X7
  • Structure-Activity Relationship


  • Anti-Inflammatory Agents
  • Interleukin-1beta
  • P2RX7 protein, human
  • Purinergic P2 Receptor Antagonists
  • Pyrazoles
  • Receptors, Purinergic P2
  • Receptors, Purinergic P2X7
  • Ethidium