Analytical profile, in vitro metabolism and behavioral properties of the lysergamide 1P‐AL‐LAD

Lysergic acid diethylamide (LSD) is known to induce powerful psychoactive effects in humans, which cemented its status as an important tool for clinical research. A range of analogues and derivatives has been investigated over the years, including those classified as new psychoactive substances. This study presents the characterization of the novel lysergamide N,N‐diethyl‐1‐propanoyl‐6‐(prop‐2‐en‐1‐yl)‐9,10‐didehydroergoline‐8β‐carboxamide (1P‐AL‐LAD) using various mass spectrometric, gas‐ and liquid chromatographic and spectroscopic methods. In vitro metabolism studies using pooled human liver microsomes (pHLM) confirmed that 1P‐AL‐LAD converted to AL‐LAD as the most abundant metabolite consistent with the hypothesis that 1P‐AL‐LAD may act as a prodrug. Fourteen metabolites were detected in total; metabolic reactions included hydroxylation of the core lysergamide ring structure or the N (6)‐allyl group, formation of dihydrodiol metabolites, N‐dealkylation, N (1)‐deacylation, dehydrogenation, and combinations thereof. The in vivo behavioral activity of 1P‐AL‐LAD was evaluated using the mouse head twitch response (HTR), a 5‐HT(2A)‐mediated head movement that serves as a behavioral proxy in rodents for human hallucinogenic effects. 1P‐AL‐LAD induced a dose‐dependent increase in HTR counts with an inverted U‐shaped dose–response function, similar to lysergic acid diethylamide (LSD), psilocybin, and other psychedelics. Following intraperitoneal injection, the median effective dose (ED(50)) for 1P‐AL‐LAD was 491 nmol/kg, making it almost three times less potent than AL‐LAD (174.9 nmol/kg). Previous studies have shown that N (1)‐substitution disrupts the ability of lysergamides to activate the 5‐HT(2A) receptor; based on the in vitro metabolism data, 1P‐AL‐LAD may induce the HTR because it acts as a prodrug and is metabolized to AL‐LAD after administration to mice.