Return of the lysergamides. Part II: Analytical and behavioural characterization of N6 -allyl-6-norlysergic acid diethylamide (AL-LAD) and (2'S,4'S)-lysergic acid 2,4-dimethylazetidide (LSZ)

Abstract

Lysergic acid N,N-diethylamide (LSD) is perhaps one of the most intriguing psychoactive substances known and numerous analogs have been explored to varying extents in previous decades. In 2013, N⁶ -allyl-6-norlysergic acid diethylamide (AL-LAD) and (2'S,4'S)-lysergic acid 2,4-dimethylazetidide (LSZ) appeared on the 'research chemicals'/new psychoactive substances (NPS) market in both powdered and blotter form. This study reports the analytical characterization of powdered AL-LAD and LSZ tartrate samples and their semi-quantitative determination on blotter paper. Included in this study was the use of nuclear magnetic resonance (NMR) spectroscopy, gas chromatography-mass spectrometry (GC-MS), low and high mass accuracy electrospray MS(/MS), high performance liquid chromatography diode array detection and GC solid-state infrared analysis. One feature shared by serotonergic psychedelics, such as LSD, is the ability to mediate behavioural responses via activation of 5-HT_2A receptors. Both AL-LAD and LSZ displayed LSD-like responses in male C57BL/6 J mice when employing the head-twitch response (HTR) assay. AL-LAD and LSZ produced nearly identical inverted-U-shaped dose-dependent effects, with the maximal responses occurring at 200 µg/kg. Analysis of the dose responses by nonlinear regression confirmed that LSZ (ED₅₀ = 114.2 nmol/kg) was equipotent to LSD (ED₅₀ = 132.8 nmol/kg) in mice, whereas AL-LAD was slightly less potent (ED₅₀ = 174.9 nmol/kg). The extent to which a comparison in potency can be translated directly to humans requires further investigation. Chemical and pharmacological data obtained from NPS may assist research communities that are interested in various aspects related to substance use and forensic identification. Copyright © 2016 John Wiley & Sons, Ltd.

Keywords: 5-HT2A receptors; LSD; lysergamides; new psychoactive substances; psychedelics.

Figure 1

Structural representations of AL-LAD, LSZ and related lysergamides.

Figure 2

Electron ionization mass spectrum and Kovats retention index recorded for AL-LAD.

Figure 3

(A). Partial gas chromatography mass spectrometry trace where five LSZ isomers were detected. Three major isomers were labeled as LSZ I–III. Two minor isomers were also detected at 26.30 and 26.76 min. The corresponding mass spectra are shown as Supporting Information. (B)–(D). Electron ionization mass spectra recorded for LSZ isomers I–III. The Kovats retention indices have also been added to the spectra.

Figure 3

(A). Partial gas chromatography mass spectrometry trace where five LSZ isomers were detected. Three major isomers were labeled as LSZ I–III. Two minor isomers were also detected at 26.30 and 26.76 min. The corresponding mass spectra are shown as Supporting Information. (B)–(D). Electron ionization mass spectra recorded for LSZ isomers I–III. The Kovats retention indices have also been added to the spectra.

Figure 4

Comparison of electrospray ionization single and tandem mass spectra. (A). Quadrupole time of flight tandem mass spectrum (ESI-QTOF-MS/MS) recorded for AL-LAD. (B) and (C). In-source CID spectra of AL-LAD under single quadrupole mass spectrometry (HPLC-Q-MS) conditions. (D). HPLC-Q-MS trace using the m/z value of the protonated molecule for selected ion monitoring (SIM). (E). HPLC diode array analysis of AL-LAD.

Figure 5

Comparison of electrospray ionization single and tandem mass spectra. (A). Quadrupole time of flight tandem mass spectrum (ESI-QTOF-MS/MS) recorded for LSZ. (B)/(C) and (D)/(E): In-source CID spectra of LSZ-1 and LSZ-2 under single quadrupole mass spectrometry (HPLC-Q-MS) conditions. (F). HPLC-Q-MS trace using the m/z value of the protonated molecule for selected ion monitoring (SIM). (G). HPLC diode array analysis of LSZ.

Figure 6

GC-solid state-IR spectrum of AL-LAD. Top: entire scan range. Bottom: partial scan range.

Figure 7

Partial, overlaid GC-solid state-IR spectra and Kovats retention indices of LSZ isomers I–III for comparison. Individual spectra including the entire scan range are available as Supporting Information.

Figure 8

Effects of AL-LAD (A) and LSZ (B) on the head twitch response. Data are presented as group means ± SEM for the entire 30-min test session. *p < 0.01, significant differences from vehicle control group (Tukey's test).