2 research outputs found
Discovery of a Novel Class of Bicyclo[3.1.0]hexanylpiperazines as Noncompetitive Neuropeptide Y Y1 Antagonists
A novel class of bicyclo[3.1.0]Âhexanylpiperazine neuropeptide
Y (NPY) Y1 antagonists has been designed and synthesized. Scatchard
binding analysis showed these compounds to be noncompetitive with
[<sup>125</sup>I]ÂPYY binding to the Y1 receptor. The most potent member,
1-((1α,3α,5α,6β)-6-(3-ethoxyphenyl)-3-methylbicyclo[3.1.0]Âhexan-6-yl)-4-phenylpiperazine
(<b>2</b>) had an IC<sub>50</sub> = 62 nM and displayed excellent
oral bioavailability in rat (% <i>F</i> po = 80), as well
as good brain penetration (B/P ratio = 0.61). In a spontaneous nocturnal
feeding study with male Sprague–Dawley rats, <b>2</b> significantly reduced food intake during a 12 h period
Acyl Guanidine Inhibitors of β‑Secretase (BACE-1): Optimization of a Micromolar Hit to a Nanomolar Lead via Iterative Solid- and Solution-Phase Library Synthesis
This report describes the discovery and optimization
of a BACE-1
inhibitor series containing an unusual acyl guanidine chemotype that
was originally synthesized as part of a 6041-membered solid-phase
library. The synthesis of multiple follow-up solid- and solution-phase
libraries facilitated the optimization of the original micromolar
hit into a single-digit nanomolar BACE-1 inhibitor in both radioligand
binding and cell-based functional assay formats. The X-ray structure
of representative inhibitors bound to BACE-1 revealed a number of
key ligand:protein interactions, including a hydrogen bond between
the side chain amide of flap residue Gln73 and the acyl guanidine
carbonyl group, and a cation−π interaction between Arg235
and the isothiazole 4-methoxyphenyl substituent. Following subcutaneous
administration in rats, an acyl guanidine inhibitor with single-digit
nanomolar activity in cells afforded good plasma exposures and a dose-dependent
reduction in plasma Aβ levels, but poor brain exposure was observed
(likely due to Pgp-mediated efflux), and significant reductions in
brain Aβ levels were not obtained