Peptides which effect release of hormones

Abstract

The present invention relates to peptides which possess biological activity in respect to the inhibition of growth hormone, insulin .[.secretion.]. and glucagon secretion .[.are provided.].. The peptides have fewer amino acid components than somatostatin and some of the peptides have dissociated activity. .Iadd.

What is claimed is: 
     
       1. A peptide selected from those of the formulae: ##STR3## wherein R 1  is selected from the group consisting of Asn and desR 1  ; R 2  is selected from the group consisting of Trp and D-Trp; R 3  is selected from the group consisting of Phe and Thr; R 4  is selected from group consisting of Thr and desR 4  ; R 5  is selected from the group consisting of Ser, Phe and desR 5 , provided that at least one of R 1 , R 4  and R 5  is deleted; X is selected from the group consisting of H, and an alpha-amino protecting group; X 1  and X 6  are selected from the group consisting of H and a protecting group for Cys selected from S-p-methoxybenzyl, S-acetamidomethyl, S-trityl and S-benzyl; X 2  is selected from the group consisting of H and a side chain amino protecting group; X 3 , X 4  and X 5  are selected from the group consisting of H and a hydroxyl protecting group selected from the group consisting of acetyl, benzoyl, tert-butyl, trityl, benzyl and benzyloxycarbonyl; with the proviso that at least one of X, X 1 , X 2 , X 3 , X 4 , X 5 , and X 6  is other than hydrogen; .[.and.]. R 6  is selected from the group consisting of hydroxy, methoxy, and an anchoring bond used in solid phase synthesis linked to a solid resin support selected from the group consisting of --O--CH 2  -polystyrene resin support and O--CH 2  -benzylpolystyrene resin support.Iadd.; and Cys is either L-Cys or D-Cys.Iaddend.. 
     
     
       2. A peptide in accordance with claim 1 wherein R 1  is des R 1 , R 2  is D-Trp, R 3  is .[.Phe.]. .Iadd.Thr.Iaddend., R 4  is desR 4  and R 5  is desR 5 . 
     
     
       3. A peptide in accordance with claim 1 wherein R 1  is desR 1 , R 2  is D-Trp, R 3  is .[.Phe.]. .Iadd.Thr.Iaddend., R 4  is DesR 4 , R 5  is desR 5  and .[.D-Cys is substituted for.]. Cys 11  is D-Cys. 
     
     
       4. A peptide in accordance with claim 1 wherein R 1  is desR 1 , R 2  is D-Trp, R 3  is .[.Phe.]. .Iadd.Thr.Iaddend., R 4  is .[.desR 4  .]. .Iadd.Thr .Iaddend.and R 5  is desR 5 . 
     
     
       5. A peptide in accordance with claim 1 wherein R 1  is Asn, R 2  is D-Trp, R 3  is .[.Phe.]. .Iadd.Thr.Iaddend., R 4  is desR 4  and R 5  is desR 5 . 
     
     
       6. A peptide in accordance with claim 1 wherein R 1  is Asn, R 2  is Trp, R 3  is .[.Phe.]. .Iadd.Thr.Iaddend., R 4  is Thr and R 5  is desR 5 . 
     
     
       7. A peptide in accordance with claim 1 wherein R 1  is Asn, R 2  is D-Trp, R 3  is .[.Phe.]. .Iadd.Thr.Iaddend., R 4  is Thr and R 5  is des R 5 .