Molecular conformations of aminophenylimidazoles exhibiting antiulcer activities.
作者:Toshimasa ISHIDA、Yasuko IN、Masatoshi INOUE、Takushi KURIHARA、Kazuhiro MORIMOTO、Katsuaki MORISAKA、Kenyu SHIBATA
DOI:10.1248/cpb.38.1803
日期:——
To experimentally clarify a possible stereostructure-activity relationship proposed for H2-receptor antagonists, three 5-aminophenylimidazoles (1, 2 and 3), in which respective amino groups are located on the ortho, meta and para positions of the benzene ring, were synthesized and examined for their conformational characteristics using X-ray diffraction and proton nuclear magnetic resonance ( 1H-NMR) methods, and for antiulcer activities on rats and H2-receptor antagonist activities in guinea pig. The ortho isomer 1, which preferentially formed an intramolecular N-H (amino)…N (imidazole) hydrogen bond, showed the highest antiulcer activity with half the efficacy of cimetidine. On the other hand, none of 1, 2 and 3 showed significant H2-receptor antagonist activity. Based on these results, the conformational characteristic for the exhibition of antiulcer activity has been discussed.
为了通过实验澄清 H2 受体拮抗剂可能存在的立体结构-活性关系,我们合成了三种 5-氨基苯基咪唑(1、2 和 3),其中的氨基分别位于苯环的正位、偏位和对位,并使用 X 射线衍射和质子核磁共振(1H-NMR)方法检测了它们的构象特征,以及在大鼠身上的抗溃疡活性和在豚鼠身上的 H2 受体拮抗剂活性。正交异构体 1 优先形成分子内 N-H(氨基)......N(咪唑)氢键,显示出最高的抗溃疡活性,药效是西咪替丁的一半。另一方面,1、2 和 3 均未显示出明显的 H2 受体拮抗剂活性。基于这些结果,我们对显示抗溃疡活性的构象特征进行了讨论。