Synthesis and biological assays of new H3-antagonists with imidazole and imidazoline polar groups
作者:Marco Mor、Fabrizio Bordi、Claudia Silva、Silvia Rivara、Valentina Zuliani、Federica Vacondio、Giovanni Morini、Elisabetta Barocelli、Vigilio Ballabeni、Mariannina Impicciatore、Pier Vincenzo Plazzi
DOI:10.1016/s0014-827x(99)00115-9
日期:2000.1
New histamine H-3-receptor antagonists were synthesised and tested on rat brain membranes and on electrically stimulated guinea-pig ileum. The new compounds have a central polar group represented by a 2-alkylimidazole or a 2-thioimidazoline nucleus. The effect of the polar group basicity on the optimal length of the alkyl chain, connecting this group to a 4(5)-imidazolyl ring, was investigated. The best affinity values, obtained by displacement of [H-3]-RAMHA from rat brain, were obtained for the 2-alkylimidazole derivatives (2a-f) with tetramethylene chain (pK(i) 8.03-8.97), having an intermediate basicity between that of the previously reported 2-thioimidazoles (1a-i) and that of 2-alkylthioimidazolines (3a-h). In contrast, a general lowering of affinity (pK(i) 5.90-7.63) was observed for compounds of the last series (3a-h), with a complex dependence on the terminal lipophilic group and chain length. (C) 2000 Elsevier Science S.A. All rights reserved.