4-AcO-DMT, commonly called psilacetin or O-acetylpsilocin, is a synthetic tryptamine and the acetylated analogue of psilocin (4-HO-DMT). It has an acetoxy group at the 4-position of the indole ring and two methyl groups on the terminal nitrogen. Research indicates that it can be hydrolysed to psilocin, although the extent of conversion in humans has not been fully established.
Chemistry and relationship to psilocin
4-AcO-DMT retains the basic tryptamine structure of psilocin, with an acetyl group attached to the oxygen at position 4. This makes it an ester rather than a phosphate derivative such as psilocybin. For analytical identification, the distinction matters: psilocybin, psilocin and psilacetin are related compounds, but they are not interchangeable names for the same molecule.
Psilacetin has appeared in research-chemical markets as a synthetic 4-substituted tryptamine. Its structural relationship to psilocin has led researchers to investigate whether it acts mainly as a precursor that releases psilocin after hydrolysis.
Pharmacology
A 2020 study examined 4-AcO-DMT and related tryptamines at human and mouse serotonin receptors. In the human 5-HT2A assay, 4-AcO-DMT showed agonist activity, although its efficacy was lower than the serotonin reference response. It also produced a dose-related head-twitch response in mice, a behavioural model associated with 5-HT2A activation. The authors noted that O-acetylation reduced some in-vitro measures of activity but had little effect on the behavioural response, which is consistent with deacetylation in vivo (Klein and colleagues, 2021).
Metabolism
A 2022 study investigated 4-AcO-DMT in pooled human liver microsomes. Fifteen metabolites were proposed: 12 phase I and three phase II products. The pathways included hydrolysis, hydroxylation, N-demethylation, oxidation and glucuronide conjugation. Hydrolysis to psilocin was the most prominent transformation in the experimental system. The authors also proposed a hydroxylated metabolite as a possible forensic biomarker (Zhai and colleagues, 2022).
These results support the idea that 4-AcO-DMT can act as a precursor to psilocin. They do not establish the exact proportions or timing of conversion in living people.
Reported effects and clinical evidence
Human descriptions often compare psilacetin with psilocin-containing mushrooms. Such comparisons are consistent with the proposed metabolic relationship, but controlled human evidence is too limited to define the effects of 4-AcO-DMT separately or establish how much activity comes from the parent compound.
There is no well-characterised human concentration-toxicity relationship, and long-term safety and dependence potential have not been adequately studied.
Related tryptamines
4-AcO-DMT is related to 4-HO-DMT (psilocin), 4-AcO-MET, 4-AcO-DET and 4-AcO-MiPT. Its N,N-dimethyl side chain distinguishes it from the other acetoxy tryptamines.
