Synthesis, novel crystal structure, and β-Amyloid binding property of Re(I) (tricarbonyl) + EHIDA analogue

Abstract

A neutral compound Re(CO)3 (L) (L: 2-((2-(2,6- diethylphenylamino)-2-oxoethyl)(2-ethoxy-2-oxoethyl)amino)acetic acid, an IDA analogue) has been synthesized and evaluated for in vitro imaging probes of β-amyloid (Aβ ) aggregates. Results of X-ray measurement of Re(CO)3 (L) demonstrated that the coordination mode of Re(CO) 3 (L) was different from that of classical Re/Tc(I) (tricarbonyl)-IDA analogues; the structure of Re(CO) 3 (L) was confirmed by means of infrared spectrum, HPLC-UV, TOF MS, and X-ray measurements (Cambridge Crystallographic Data Centre number is 732731): monoclinic P 21 / c, a=15.6636 (12)Å, b=10.9360 (8) Å, c=27.756 (2) Å, α=90.000 (0)° β, =90.783 (5), γ=90.000 (0), and Z=8. The binding affinity for β-amyloid plaques was assessed by in vitro binding assay using preformed synthetic A β(1 40) aggregates. The neutral compound Re(CO)3 (L) showed binding affinity to A β aggregates at micromolar level by fluorescence spectroscopy, and this work will encourage for further exploration of imaging agents labeled by 99m Tc (CO) 3+ center as probes for β-amyloid plaques in vivo. Copyright © 2009 Yang Yang et al.