Synthesis and biological activity of tetragastrin analogues modifying the tryptophan residue.

Abstract
Three analogues of tetragastrin, in which the tryptophan residue was substituted by 3-(1-naphthyl)-L-alanine, 3-(2-naphthyl)-L-alanine or 1,2,3,4-tetrahydro-.beta.-carboline-3-carboxylic acid, were synthesized and evaluated for their gastric juice stimulating activity [in the rat]. Indolyl NH function in the tryptophan residue may play an important role, and the role of tryptophan residue in an interaction between tetragastrin and its receptor may be different from that in the case of luteinizing hormone-releasing hormone.