A series of P1-P3 linked macrocyclic BACE-1 inhibitors containing a hydroxyethylamine (HEA) isostere scaffold has been synthesized. All inhibitors comprise a toluene or Nphenylmethanesulfonamide P2 moiety. Excellent BACE-1 potencies, both in enzymatic and cell-based assays, were observed in this series of target compounds, with the best candidates displaying cell-based IC 50 values in the low nanomolar range. As an attempt to improve potency, a phenyl substituent aiming at the S3 subpocket was introduced in the macrocyclic ring. X-ray analyses were performed on selected compounds, and enzymeinhibitor interactions are discussed.

The use of hyphenated analytical techniques in forensic drug screening enables simultaneous identification of a wide range of different compounds. However, the appearance of drug seizures containing new substances, mainly new psychoactive substances (NPS), is steadily increasing. These new and other already known substances often possess structural similarities and consequently they exhibit spectral data with slight differences. This situation has made the criteria that ensure indubitable identification of compounds increasingly important. In this work, 6 new synthetic cathinones that have not yet appeared in any Swedish drug seizures were synthesized. Their chemical structures were similar to those of already known cathinone analogs of which 42 were also included in the study. Hence, a total of 48 synthetic cathinones making up sets of homologous and regioisomeric compounds were used to challenge the capabilities of various analytical techniques commonly applied in forensic drug screening, ie, gas chromatography-mass spectrometry (GC-MS), gas chromatography-Fourier transform infrared spectroscopy (GC-FTIR), nuclear magnetic resonance (NMR), and liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS). Special attention was paid to the capabilities of GC-MS and GC-FTIR to distinguish between the synthetic cathinones and the results showed that neither GC-MS nor GC-FTIR alone can successfully differentiate between all synthetic cathinones. However, the 2 techniques proved to be complementary and their combined use is therefore beneficial. For example, the structural homologs were better differentiated by GC-MS, while GC-FTIR performed better for the regioisomers. Further, new spectroscopic data of the synthesized cathinone analogs is hereby presented for the forensic community. The synthetic work also showed that cathinone reference compounds can be produced in few reaction steps.

Novel BACE-1 inhibitors with a hydroxyethylene central core have been developed. Modified P1´ and extended P1 substituents were incorporated with the aim to explore potential interactions with the S1´ and the S1-S3 pocket, respectively, of BACE-1. Inhibitors were identified displaying IC50 values in the nanomolar range, i.e. 69 nM for the most potent compound. Possible inhibitor interactions with the enzyme are also discussed.

A series of arylketo-containing P1-P3 linked macrocyclic BACE-1 inhibitors were designed, synthesized, and compared with compounds with a previously known and extensively studied corresponding P2 isophthalamide moiety with the aim to improve on permeability whilst retaining the enzyme- and cell-based activities. Several inhibitors displayed substantial increases in Caco-2 cell-based permeability compared to earlier synthesized inhibitors and notably also with retained activities, showing that this approach might yield BACE-1 inhibitors with improved properties.