77-LH-28-1
77-LH-28-1 is a selective agonist of muscarinic acetylcholine receptor subtype 1 discovered in 2008. It is an allosteric agonist, exhibiting over 100-fold specificity for M1 over other muscarinic receptor subtypes. 77-LH-28-1 penetrates the brain by crossing the blood–brain barrier and is therefore a useful pharmacological tool with cognition enhancing effects. It has been used as a lead compound for discovery of other M1 agonists, and a crystal structure of the bound complex between 77-LH-28-1 and the M1 receptor has been published.