Propylnorapomorphine is a potent and selective D2 receptor agonist. Propylnorapomorphine is used as a tool compound to label dopamine receptors in rodent brain, and elicits dopaminergic behavioural effects. It stimulates motor activity, induces stereotypic behaviour and sexual stimulation. Propylnorapomorphine was investigated in clinical trial against Parkinson's disease and schizophrenia

Coptisine (COP), a protoberberine alkaloid, is widely found in Chinese medicinal plants (family Berberidaceae, Ranunculaceae and Papaveraceae). It is reported that COP has a wide range of pharmacological and biological activities, including antibacterial, hypoglycemic, anti-tumorigenic, and gastric-mucous membrane protection. Considerable attention has been focused on its activity against central nervous system disorders, such as improving the symptoms of Alzheimer’s disease and even preventing its onset, by exerting antidepressant effects as a potent type A monoamine oxidase inhibitor. Coptisine was found to be an efficient uncompetitive Indoleamine 2,3-dioxygenase inhibitor. Coptisine is a potent inhibitor of human organic cation transporters.