Identification of prostaglandin D2 receptor antagonists based on a tetrahydropyridoindole scaffold

A new series of indole-based antagonists of the PGD2 receptor subtype 1 (DP1 receptor) was identified and the progress of the structure–activity relationship study to the identification of potent and selective antagonists is presented. Selective DP1 antagonists with high potency and selectivity were prepared. Of particular interest is the DP1 antagonist 26 with a Ki value of 1 nM for the DP1 receptor and an IC50 value of 4.6 nM in a DP1 functional assay for the inhibition of the PGD2 induced cAMP production in platelet rich plasma (PRP).