Synthesis of Dihydrofuroaporphine Derivatives: Identification of a Potent and Selective Serotonin 5-HT1A Receptor Agonist

A series of new aporphine analogues were synthesized and pharmacologically evaluated. 11-Allyloxy-(17), 11-propargyloxy-(20), and dihydrofuro-(19) aporphines displayed the highest affinity at the 5-HT1A receptor with K i values of 12.0, 14.0, and 6.7 nM, respectively. The high binding potential of the diastereomeric mixture of aporphine 19 was found residing in the cis-diastereomer (cis-19). [35S]GTPγS function assays on 5-HT1A receptor indicated that aporphines 17 and 20 were partial agonists, while trans-19 behaved as a high efficacy full antagonist and cis-19 was a full agonist. The agonistic property of cis-19 at the 5-HT1A receptor was further confirmed in vitro and in vivo. This compound may be useful as a potential treatment for anxiety.