Bradykinin analogues containing N alpha-methyl amino acids

Analogues of bradykinin were synthesized containing single substitutions by N alpha-methyl amino acids in the 1, 4, 5, 5, and 9 positions. [MeArg]Bradykinin possessed 60% of the muscle-contracting activity of the parent compound in a guinea pig ileum assay. The other analogues were very weak agonists (less than 2%) and, disappointingly, failed to show blocking activity except at very high doses.