Synthesis and biological properties of vasopressin analogues containing 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid

Solid phase synthesis methodology on a benzhydrylamine resin was used for the synthesis of three analogues of vasopressin with the non-coded amino acid, 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (Tic), in the position 2 ([Tic 2 , Lys 8 ]VP ( I )) and in the position 3 ([Tic 3 , Lys 8 ]VP ( II )). The analogue containing only one Tic in place of both aromatic residues was also isolated (des-Tyr 2 -[Tic 3 , Lys 8 ]VP ( III )). The biological activities of all analogues were negligible.