Histamine H 1 receptor ligands : Part II. Synthesis and in vitro pharmacology of 2-[2-(phenylamino)thiazol-4-yl]ethanamine and 2-(2-benzhydrylthiazol-4-yl)ethanamine derivatives

Abstract

New 2-[2-(phenylamino)thiazol-4-yl]ethanamine and 2-(2-benzhydrylthiazol-4-yl)ethanamine derivatives were prepared and tested in vitro as H 1 receptor antagonists. The compounds with 2-phenylamino substitution with meta-halide substituents at the phenyl ring, showed weak H 1-antagonistic activity (pA 2: 4.62–5.04) and this activity was completely lost in the case of meta-methyl substituent (pA 2<4). When the phenylamino group was replaced by benzhydryl groups of classic antihistamines, the resulting compounds exhibited slightly improved H 1-antagonistic activity (at the meta-position pA 2: 6.38–6.15; at the para-position pA 2: 6.04–5.87).