Potential antihypertensive benzimidazole derivatives.

A series of benzimidazole derivatives was synthesized and tested for their hypotensive activity. The most interesting compounds were: BS1/81 (2-guanidino-benzimidazole) and BS1/84 (2-guanidino-5-aminobenzimidazole dihydrochloride), which effects were comparable to those of aminophylline. It was found that substitution of guanidine nitrogen atom with phenyl group caused a distinct decrease of activity while cyclization of guanidine rest to pyrimidine ring caused only a small decrease of activity.