Study of the in vitro and in vivo metabolism of 4-HO-MET
Pia Simona Bruni, Katharina Elisabeth Grafinger, Susanne Nussbaumer, Stefan König, Stefan Schürch, Wolfgang Weinmann
Forensic Science International July 4, 2018 DOI: 10.1016/j.forsciint.2018.06.037 via OpenAlex
Summary
AI-generated from the abstract4-Hydroxy-N-methyl-N-ethyltryptamine (4-HO-MET), a new psychoactive substance structurally similar to serotonin, is a serotonergic hallucinogen. To enable forensic urine analysis, its biotransformation was studied using pooled human liver microsomes and three authentic urine samples. Twelve different in vitro and four in vivo metabolites were identified. In vitro, major biotransformation steps included mono- or dihydroxylation, demethylation, demethylation with monohydroxylation, carboxylic acid formation, deethylation, and oxidative deamination. In vivo, monohydroxylation and glucuronidation were observed. A metabolic pathway was proposed. For forensic urine analysis, the N-oxide metabolite, HO-alkyl metabolite, glucuronides of 4-HO-MET, and the parent compound are recommended as target compounds.
Study at a glance
| Characteristics | In vitro and in vivo metabolic study Peer reviewed |
|---|---|
| Population | Human liver microsomes and three human urine samples |
| Keywords | Metabolite Glucuronidation Oxidative deamination In vivo Designer drug |
| Citations | 13 |
| Key finding | Twelve in vitro and four in vivo metabolites of 4-HO-MET were identified, with monohydroxylation and glucuronidation as key in vivo transformations. |
Abstract
4-Hydroxy-N-methyl-N-ethyltryptamine (4-HO-MET) is a new psychoactive substance (NPS) of the chemical class of tryptamines. It shows structural similarities to the endogenous neurotransmitter serotonin, and is a serotonergic hallucinogen, affecting emotional, motoric, and cognitive functions. The knowledge about its biotransformation is mandatory to confirm the abuse of the substance by urine analysis in forensic cases. Therefore, phase I metabolites were generated by the use of the pooled human liver microsomes (pHLM) in vitro model and analyzed by high-performance liquid chromatography high-resolution tandem mass spectrometry with information-dependent acquisition (HPLC-IDA-HR-MS/MS). Furthermore, three authentic urine samples was analyzed and results were compared: 12 different in vitro and 4 in vivo metabolites were found. The predominant biotransformation steps observed in vitro were mono- or dihydroxylation of 4-HO-MET, besides demethylation, demethylation in combination with monohydroxylation, formation of a carboxylic acid, deethylation, and oxidative deamination. In vivo, monohydroxylation, and glucuronidation were detected. A metabolic pathway based on these results was proposed. For the analysis of urine samples in forensic cases, the N-oxide metabolite and the HO-alkyl metabolite are recommended as target compounds, besides the glucuronides of 4-HO-MET and the parent compound 4-HO-MET itself.