Synthesis and Biological Activity of Various Derivatives of a Novel Class of Potent, Selective, and Orally Active Prostaglandin D2 Receptor Antagonists. 1. Bicyclo[2.2.1]heptane Derivatives

Novel prostaglandin D2 (PGD2) receptor antagonists were synthesized as a potential new class of antiallergic agents having a bicyclo[2.2.1]heptane ring system with sulfonamide groups. Some of them exhibit extremely potent antagonism of the PGD2 receptor in radioligand binding and cAMP formation assays with IC50 values below 50 nM and much less antagonism of TXA2 and PGI2 receptors. These potent PGD2 receptor antagonists, when given orally, dramatically suppress various allergic inflammatory responses such as increased vascular permeability in allergic rhinitis, conjunctivitis, and asthma models. The excellent pharmacological profiles of PGD2 receptor antagonists, originally synthesized in our laboratories, are of potentially great clinical significance. This study also provides experimental evidence suggesting that PGD2 plays an important role in the pathogenesis of allergic diseases.