1234567Rudin D, McCorvy JD, Glatfelter GC, Luethi D, Szöllősi D, Ljubišić T, etal. (March 2022). "(2-Aminopropyl)benzo[β]thiophenes (APBTs) are novel monoamine transporter ligands that lack stimulant effects but display psychedelic-like activity in mice". Neuropsychopharmacology. 47 (4): 914–923. doi:10.1038/s41386-021-01221-0. PMC8882185. PMID34750565. The 5-HT2A receptor is the primary target for LSD, psilocybin, and other hallucinogenic drugs in the brain [76, 77]. Other hallucinogenic drugs acting strongly at 5-HT2A include 3-API [78, 79], while, by contrast, 5-API displays a much lower potency and efficacy [18]. Hence, the interaction of APIs with the 5-HT2A receptor is dependent on the position of the alkylamine side chain on the indole ring. Although relevant data have not been reported for 3-APB, the 5-methoxy-substituted derivative 5-methoxy-3-(2-aminopropyl)benzofuran has high affinity for 5-HT2A sites [80]. In line with the activity of 5-API, both 5-APB and 6-APB have been shown to be active at 5-HT2A with relatively low potency and efficacy [20]. Given those previous findings, it is notable that 3-APBT, 5-APBT, and 6-APBT are highly efficacious 5-HT2A agonists. Hence, compared to APIs and APBs, the ability of APBTs to activate the 5-HT2A receptor does not depend on side chain position.
12Nichols DE (2017). "Chemistry and Structure–Activity Relationships of Psychedelics". Behavioral Neurobiology of Psychedelic Drugs. Current Topics in Behavioral Neurosciences. Vol.36. Berlin, Heidelberg: Springer Berlin Heidelberg. pp.1–43. doi:10.1007/7854_2017_475. ISBN978-3-662-55878-2. PMID28401524.