Analytical and behavioral characterization of 1‐hexanoyl‐LSD (1H‐LSD)

Abstract The development of lysergic acid diethylamide (LSD) derivatives and analogs continues to inform the design of novel receptor probes and potentially new medicines. On the other hand, a number of newly developed LSD derivatives have also emerged as recreational drugs, leading to reports of their detection in some countries. One position in the ergoline scaffold of LSD that is frequently targeted is the N 1 ‐position; numerous N 1 ‐alkylcarbonyl LSD derivatives have been reported where the acyl chain is attached to the indole nitrogen, for example, in the form of linear n ‐alkane substituents, which represent higher homologs of the prototypical 1‐acetyl‐ N , N ‐diethyllysergamide (1A‐LSD, ALD‐52). In this study, 1‐hexanoyl‐LSD (1H‐LSD, SYN‐L‐027), a novel N 1 ‐acyl LSD derivative, was characterized analytically using standard techniques, followed by evaluation of its in vivo behavioral effects using the mouse head‐twitch response (HTR) assay in C57BL/6J mice. 1H‐LSD induced the HTR, with a median effective dose (ED 50 ) of 192.4 μg/kg (equivalent to 387 nmol/kg), making it roughly equipotent to ALD‐52 when tested previously under similar conditions. Similar to other N 1 ‐acylated analogs, 1H‐LSD is anticipated to by hydrolyzed to LSD in vivo and acts as a prodrug. It is currently unknown whether 1H‐LSD has appeared as on the research chemical market or is being used recreationally.