Snythesis and structure-activity relationships of indole and benzimidazole piperazines as histamine H-4 receptor antagonists

Abstract

We describe the structure-activity relationships for a series of ligands structurally related to the recently identified (5-chloro-1H-indol-2-yl)-(4-methyl-piperazin-1-yl)-methanone (1) as histamine H-4 receptor (H4R) antagonists. Furthermore we identified related benzimidazoles as novel lead compounds for the H4R. The ligands have been evaluated by radioligand displacement studies and functional assays for their interaction with both the human histamine H-3 and H-4 receptors and exhibit pK(i) values up to 7.5 at the human H4R. (C) 2004 Elsevier Ltd. All rights reserved.