Coclaurine is a nicotinic acetylcholine receptor antagonist which has been isolated from a variety of plant sources including Nelumbo nucifera, Sarcopetalum harveyanum,Ocotea duckei,and others. It belongs to the class of tetrahydroisoquinoline alkaloids. Dimerization of coclaurine leads to the biscoclaurine alkaloids such as cepharanthine.