Metabolism of the tryptamine-derived new psychoactive substances 5-MeO-2-Me-DALT, 5-MeO-2-Me-ALCHT, and 5- MeO-2-Me-DIPT and their detectability in urine studied by GC-MS, LC-MSn, and LC-HR-MS/MS

Many N,N-dialkylated tryptamines show psychoactive properties and were encountered as new psychoactive substances. The aims of the presented work were to study the phase I and II metabolism and the detectability in standard urine screening approaches (SUSA) of 5-methoxy-2-methyl-N,N- diallyltryptamine (5-MeO-2-Me-DALT), 5-methoxy-2-methyl-N-allyl-N- cyclohexyltryptamine (5-MeO-2-Me-ALCHT), and 5-methoxy-2-methyl-N,N- diisopropyltryptamine (5-MeO-2-Me-DIPT) using GC-MS, LC-MSn, and LC- HR-MS/MS. For metabolism studies, urine was collected over a 24-h period after administration of the compounds to male Wistar rats at 20 mg/kg body weight (BW). Phase I and II metabolites were identified after urine precipitation with acetonitrile by LC-HR-MS/MS. 5-MeO-2-Me-DALT (24 phase I and 12 phase II metabolites), 5-MeO-2-Me-ALCHT (24 phase I and 14 phase II metabolites), and 5-MeO-2-Me-DIPT (20 phase I and 11 phase II metabolites) were mainly metabolized by O-demethylation, hydroxylation, N-dealkylation, and combinations of them as well as by glucuronidation and sulfation of phase I metabolites. Incubations with mixtures of pooled human liver microsomes and cytosols (pHLM and pHLC) confirmed that the main metabolic reactions in humans and rats might be identical. Furthermore, initial CYP activity screenings revealed that CYP1A2, CYP2C19, CYP2D6, and CYP3A4 were involved in hydroxylation, CYP2C19 and CYP2D6 in O-demethylation, and CYP2C19, CYP2D6, and CYP3A4 in N- dealkylation. For SUSAs, GC-MS, LC-MSn, and LC-HR-MS/MS were applied to rat urine samples after 1 or 0.1 mg/kg BW doses, respectively. In contrast to the GC-MS SUSA, both LC-MS SUSAs were able to detect an intake of 5-MeO-2-Me-ALCHT and 5-MeO-2-Me-DIPT via their metabolites following 1 mg/kg BW administrations and 5-MeO-2-Me-DALT following 0.1 mg/kg BW dosage