Synthesis and Functional Characterization of 2-(2,5-Dimethoxyphenyl)-N-(2-fluorobenzyl)ethanamine (25H-NBF) Positional Isomers

Serotonergic psychedelics, substances exerting their pharmacological action through activation of the serotonin 2A receptor (5-HT2AR), have continuously comprised a substantial fraction of the over 1000 reported New Psychoactive Substances (NPS) so far. Within this category, N-benzyl derived phenethylamines, such as NBOMes and NBFs, have shown to be of particular relevance. As these substances remain incompletely characterized, this study aimed at synthesizing positional isomers of 25H-NBF, with two methoxy groups placed on different positions of the phenyl group of the phenethylamine moiety. These isomers were then functionally characterized in an in vitro bioassay monitoring the recruitment of beta-arrestin 2 to the 5HT(2A)R through luminescent readout via the NanoBiT technology. The obtained results provide insight into the optimal substitution pattern of the phenyl group of the phenethylamine moiety of N-benzyl derived substances, a feature so far mostly explored in the phenethylamines underived at the N-position. In the employed bioassay, the most potent substances were 24H-NBF (EC50 value of 158 nM), 26H-NBF (397 nM), and 25H-NBF (448 nM), with 23H-NBF, 35H-NBF, and 34H-NBF yielding mu M EC50 values. A similar ranking was obtained for the compounds' efficacy: taking as a reference LSD (lysergic acid diethylamide), 24H-, 26H-, and 25H-NBF had an efficacy of 106-107%, followed by 23H-NBF (96.1%), 34H-NBF (75.2%), and 35H-NBF (58.9%). The stronger activity of 24H-, 25H-, and 26H-NBF emphasizes the important role of the methoxy group at position 2 of the phenethylamine moiety for the in vitro functionality of NBF substances.

Automated summary

Selective serotonergic psychedelics, such as N-benzyl derived phenethylamines, have shown to be a significant fraction of New Psychoactive Substances (NPS). This study aimed to synthesize positional isomers of 25H-NBF and functionally characterize them in vitro, providing insights into the optimal substitution pattern of the phenyl group of N-benzyl derived substances. The results showed that methoxy groups at specific positions of the phenethylamine moiety play a crucial role in the functionality of NBF substances.