6-Fluorotryptamine (6-FT or 6-fluoro-T; code name PAL-227) is a serotonin receptor agonist and monoamine releasing agent (MRA) of the tryptamine family.
6-FT is known to have affinity for the serotonin 5-HT<sub>1A</sub> and 5-HT<sub>2A</sub> receptors, with K<sub>i</sub> values of 267nM and 606nM, respectively. The drug is known to act as a full agonist of the serotonin 5-HT<sub>2A</sub> receptor, with an of 4.56nM and an of 101%. Another study found values of 54nM at the serotonin 5-HT<sub>1A</sub> receptor and 81nM at the serotonin 5-HT<sub>2A</sub> receptor.
As an MRA, 6-FT is specifically a selective serotonin releasing agent (SRA). It is one of the most potent SRAs known in vitro, with an of 4.4nM in rat brain synaptosomes. It was more potent as an SRA than any other tryptamine in large series of compounds, and was second in potency of the assessed compounds only to the phenethylamine derivative naphthylaminopropane (NAP; PAL-287). 6-FT also much more weakly induces the release of dopamine and norepinephrine, with values of 106nM (24-fold lower than serotonin) and 1,575nM (358-fold lower than serotonin), respectively.
Besides its serotonin receptor agonism and monoamine release induction, 6-FT is a somewhat potent monoamine oxidase inhibitor (MAOI), with values of 1,580nM for monoamine oxidase A (MAO-A) and 5,620nM for monoamine oxidase B (MAO-B).
In contrast to analogues like 6-fluoro-AMT and 6-fluoro-DMT as well as many other tryptamines, 6-FT fails to induce the head-twitch response, a behavioral proxy of psychedelic effects, in rodents.
Tryptamines without substitutions at the amine or alpha carbon, such as tryptamine, serotonin (5-hydroxytryptamine; 5-HT), and 5-methoxytryptamine (5-MeO-T), are known to be very rapidly metabolized and thereby inactivated by monoamine oxidase A (MAO-A) in vivo and to have very short elimination half-lives. However, given intravenously at sufficiently high doses, tryptamine is still known to be able to produce weak and short-lived psychoactive effects in humans.
6-FT was first described in the scientific literature by 1995.