4-Acetoxy-N,N-dimethyltryptamine (also known as 4-AcO-DMT, 4-Acetoxy-DMT, O-Acetylpsilocin, and psilacetin) is a novel psychedelic substance of the tryptamine class. 4-AcO-DMT is chemically similar to psilocybin, the active ingredient in psilocybin mushrooms (magic mushrooms). It belongs to a group known as the substituted tryptamines which act by stimulating serotonin receptors in the brain.