https://www.selleckchem.com/pr....oducts/congo-red.htm
This article describes the discovery of novel potent muscarinic receptor antagonists identified during a search for more active histamine H3 receptor (H3R) ligands. The idea was to replace the flexible seven methylene linker with a semirigid 1,4-cyclohexylene or p-phenylene substituted group of the previously described histamine H3R antagonists ADS1017 and ADS1020. These simple structural modifications of the histamine H3R antagonist led to the emergence of additional pharmacological effects, some of which unexpectedly showed strong a