Noraporphine

Noraporphines are a class of chemical compounds related to the aporphine alkaloids like nuciferine and glaucine and synthetic aporphines like apomorphine.^[1][2] They are N-desmethyl analogues of the aporphines.^[1][2] Some noraporphines are alkaloids similarly to aporphines, for instance nornuciferine and asimilobine occurring naturally in Nelumbo nucifera and other plants.^[1][3][4]

Some noraporphines, such as asimilobine, nornuciferine, MQ02-439 (1-methoxynoraporphine), and 11-chloroasimilobine, have been found to act as potent and selective serotonin 5-HT_2C receptor agonists.^[5][6][7][8] Others, such as racemic asimilobine, 1-propoxy-2-hydroxynoraporphine, 11-methoxyasimilobine, 2-hydroxy-11-propoxynoraporphine, and 2-hydroxy-11-(2-methylallyl)oxynoraporphine, have been found to act as potent mixed serotonin 5-HT_2A and 5-HT_2C receptor agonists.^[8] Conversely, aporphines, like nuciferine, dicentrine, isolaureline, and crebanine, tend to be antagonists or very weak partial agonists of the serotonin 5-HT_2A and/or 5-HT_2C receptors,^{[9][10][11][12]} although exceptions with higher efficacy such as glaucine are known.^[10]

Many other noraporphine alkaloids are also known, including norlaureline, puterine, norstephalagine, norisocorydine, nordicentrine, norboldine (laurolistine), norpurpureine, norpredicentrine, laetanine, oduocine, norannuradhapurine, nornantenine, and norushinsunine (michelalbine), among others.^[2][13]