Bioisosteric prototype design of biaryl imidazolyl and triazolyl competitive histamine H2-receptor antagonists
摘要:
The structural relationship of the competitive histamine H2-receptor antagonist 3-amino-5-(2-amino-4-pyridyl)-1,2,4-triazole (1) to the agonist histamine and to antagonists of the cimetidine type was explored by the design and synthesis of four series of bioisosterically designed prototypes. Biological data from these series was best interpreted as indicating a similarity between the imidazole moiety of histamine and cimetidine and the 2-amino-4-pyridyl moiety of 1. On the basis of this data, sequential replacement of 2-amino-4-pyridyl by 2-[(dimethylamino)methyl]-5-furyl and 2-guanidino-4-triazolyl moieties led to a structurally more potent series of biaryl histamine H2-receptor antagonists. The best of these, 2-methyl-4-(2-guanidino-4-thiazolyl)imidazole (29, CP-57,361-1) was 120 times more potent as a histamine H2-receptor antagonist than 1.
Ranitidine (1), the histamineH2-receptorantagonist, has been previously reported to increase gastric emptying and gastric motility by inhibition of acetylcholinesterase (AChE) and enhancement of acetylcholine (ACh) release. In order to obtain potent gastroprokinetic agents, a new series of ranitidine derivatives (5-32) possessing a nitrogen atom instead of a sulfur atom (B) was synthesized and their
A furan derivative and a pharmaceutically acceptable salt thereof having gastrointestinal enterokinetic activity which is expected to be used in a broad spectrum of diseases associated with gastrointestinal dyskinesia.