D2 antagonists (1)
Pukateine is an alkaloid found in the bark of the New Zealand tree Laurelia novae-zelandiae ("Pukatea"). An extract from pukatea is used in traditional Māori herbal medicine as an analgesic, and it is thought pukateine is the active component, as it is similar in both structure and activity to alkaloids such as glaucine and tetrahydropalmatine which are found in Chinese medicinal herbs used as analgesics. Pukateine has multiple mechanisms of action, with the most prominent effects being as an agonist at the D2 dopamine receptor and antagonist at the α1-adrenergic receptor.
(−)-Stepholidine is a protoberberine alkaloid found in the plant Stephania intermedia. Stepholidine activity includes dual D2 receptor antagonist and D1 receptor agonist, and has shown antipsychotic activity in animal studies.