Synthesis and Biological Studies of Novel Bradykinin Analogues

Ten new nonapeptide and decapeptide analogues of bradykinin were prepared by solid phase synthesis. Analogues of proline ( 3,4‐dehydroproline; azetidine‐2‐carboxylic acid; cis,trans‐4‐methylproline; thiazolidine‐4‐carboxylic acid and trans‐4‐hydroxyproline ) were successfully incorporated into the peptides in place of proline at position 3. In vivo and in vitro pharmacological studies revealed that the analogues were in general less active than bradykinin. Several structure‐activity relationships were postulated from rat blood pressure, rat uterus and guinea pig ileum studies.