Identification of (2‐aminopropyl)indole positional isomers in forensic samples

Abstract

In 2012, 5-(2-aminopropyl)indole (5-API, 5-IT) was reported by Norwegian authorities to the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) via the Early Warning System (EWS). The 3- isomer, 3-(2-aminopropyl)indole (3-API, AMT, alpha-methyltryptamine), has been available on the recreational drugs market for a somewhat longer time, having first been reported to the EMCDDA by Finnish authorities in 2001. Both isomers are available from online vendors of 'legal highs'. Recently, three forensic drug cases (two tablets and one powder) were presented for routine analysis and the active constituent was tentatively identified as an API isomer. The six positional isomers (2-, 3-, 4-, 5-, 6- and 7-(2-aminopropyl)indoles) were synthesized and analyses by a combination gas chromatography-mass spectrometry (GC-MS), and liquid chromatography-mass spectrometry (LC-MS) showed that these could be readily discriminated thus facilitating the identification of 3-API in the tablets and 5-API in the powder. With exception of 5- and 6-APIs, which co-eluted, it was found possible to separate the isomers by GC without derivatization. LC separation also proved to be a feasible method for the discrimination of the isomers. Although the 2- and 7- isomers were not fully resolved by LC, it was found possible to distinguish them using their product ion spectra as the 2- isomer produced the m/z 132 fragment ion formed by loss of vinylamine, whereas the 7- isomer formed m/z 158 through loss of methylamine. In the synthesis 2-API, a novel tricyclic by-product was formed in an annulation reaction where the reaction solvent, tetrahydrofuran, was incorporated into the molecule.

5‐(2‐Aminopropyl)indole (5‐IT): a psychoactive substance used for recreational purposes is an inhibitor of human monoamine oxidase (MAO)

“…One study was identified that investigated the ability of 5-IT and its five positional isomers to inhibit monoamine oxidase (MAO). Indeed, a total number of six positional isomers exist [6,15] but information about the remaining four isomers and their activity in humans appear to be currently absent. In addition, the ability to antagonize pentylenetetrazole/reserpine-induced tonic extensor seizures in mice was also studied.…”

“…[1,9] 5-IT is a positional isomer of α-methyltryptamine (AMT, 3-IT) which also appears to be psychoactive in man [4,[10][11][12][13][14] (Figure 1B) although it is currently unclear how the psychopharmacological profiles of both substances compare. Indeed, a total number of six positional isomers exist [6,15] but information about the remaining four isomers and their activity in humans appear to be currently absent.…”

Severe serotoninergic syndrome after ingestion of α-methyltryptamine

“…So, distinguishing was only possible based on RT and not on UV data. Scott et al evaluated also this major problem of discrimination of the positional isomers by studying the identification of the six possible API compounds and of NMT [18]. In their GC/MS conditions, five of the underivatized compounds eluted in less than 0.5 min and only 2-and 7-API had an earlier RT.…”

Interactions of phenethylamine‐derived psychoactive substances of the 2C‐series with human monoamine oxidases

“…Amphetamine‐d 5 was obtained from LGC Standards (Wesel, Germany); selegiline, KYN, 4‐OHC, ammonium acetate, potassium dihydrogenphosphate, and dipotassium hydrogenphosphate from Sigma‐Aldrich (Taufkirchen, Germany); formic acid (MS grade) from Fluka (Neu‐Ulm, Germany); acetonitrile, methanol (both LC–MS grade), and all other chemicals from VWR (Darmstadt, Germany). 5‐(2‐Aminopropyl)indole (5‐IT) was synthesized and provided by the Department of Pharmacology and Therapeutics, Trinity Centre for Health Sciences, St James's Hospital (Dublin, Ireland). 2C‐B tartrate was provided for research purposes before scheduled by Hessisches Landeskriminalamt (Wiesbaden, Germany); 2C‐I hydrochloride by Landeskriminalamt Baden‐Württemberg (Stuttgart, Germany); 4‐ethylthio‐2,5‐dimethoxyphenethylamine (2C‐T‐2) hydrochloride by Bundeskriminalamt (Wiesbaden, Germany); and 4‐nitro‐2,5‐dimethoxyphenethylamine (2C‐H) and 2,5‐dimethoxy‐4‐nitrophenethylamine (2C‐N) by the Department of Forensic Toxicology, Institute of Forensic Research (Krakow, Poland).…”