New Gaba-containing analogues-of human growth hormone-releasing hormone (1-30)-amide: I. Synthesis and in vitro biological activity

I. Mezo, M. Kovacs, B. Szoke, E. Z. Szabo, J. Horváth, G. Makara, Gy Rappay, T. Janáky, I. Teplan

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Analogues of human growth hormone-releasing hormone (1-30)-amide have been developed. All analogues have been modified in position 27 with Nle and with Gaba in position 30. Additional D-amino-acids have been inserted in the GHRH(1-30)-NH2 sequence: A-1741: Nle27, Gaba30-GH-RH (1-30)-NH2 A-495: D-Ala2, Nle27, Gaba30-GH-RH (1-30)-NH2 A-515: D Ala2, Leu15, Nle27, Gaba30-GH-RH (1-30)-NH2 A-527: D-Ala2, D-Arg11, Leu15, Nle27, Gaba30-GHRH (1-30)-NH2 Our analogues were synthesized by solid phase peptide synthesis and were tested is two different in vitro systems and in rat pituitary cell cultures. A-495 and A-1741 were found to be the most active in releasing GH, however they showed different activities in the two different test systems. A-495 exhibited higher potency in the superfusion system (1.63 fold potency of the GHRH (1-29)-amide), while A-1741 evoked higher GH release from cultured pituitary cells (1.5-2.5 times higher than the GH-RH(1-44)-amide). The other analogues (A-515 and A-527) were found to be equipotent to the standard molecule. We can conclude that Nle27 and Gaba30 substitutions appeared to be a good modification in in vitro test systems, and Gaba30 substitution served as a good spacer during the synthesis, since it made the coupling of the C-terminal amino acids easier and produced quantitative coupling. In addition to the advantageous properties in the synthesis these modifications with or without D-Ala at the N-terminus increased the in vitro biological activity to 1.5-2.5 fold of the GHRH molecule. The additional substitution of Gly15 with Leu and Arg11 with D-Arg did not improve the in vitro GH-releasing activity of our analogues. A detailed in vivo investigation, which is essential for the future clinical use, has been performed and written in Part II of this paper.

Original languageEnglish
Pages (from-to)793-798
Number of pages6
JournalJournal of Endocrinological Investigation
Volume16
Issue number10
Publication statusPublished - 1993

Fingerprint

Growth Hormone-Releasing Hormone
Human Growth Hormone
Amides
Amino Acids
Solid-Phase Synthesis Techniques
Cultured Cells
Cell Culture Techniques
In Vitro Techniques
somatotropin-releasing hormone (1-30) amide

Keywords

  • Cell culture
  • Gaba
  • GH-release
  • GHRH analogues superfusion

ASJC Scopus subject areas

  • Endocrinology

Cite this

New Gaba-containing analogues-of human growth hormone-releasing hormone (1-30)-amide : I. Synthesis and in vitro biological activity. / Mezo, I.; Kovacs, M.; Szoke, B.; Szabo, E. Z.; Horváth, J.; Makara, G.; Rappay, Gy; Janáky, T.; Teplan, I.

In: Journal of Endocrinological Investigation, Vol. 16, No. 10, 1993, p. 793-798.

Research output: Contribution to journalArticle

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abstract = "Analogues of human growth hormone-releasing hormone (1-30)-amide have been developed. All analogues have been modified in position 27 with Nle and with Gaba in position 30. Additional D-amino-acids have been inserted in the GHRH(1-30)-NH2 sequence: A-1741: Nle27, Gaba30-GH-RH (1-30)-NH2 A-495: D-Ala2, Nle27, Gaba30-GH-RH (1-30)-NH2 A-515: D Ala2, Leu15, Nle27, Gaba30-GH-RH (1-30)-NH2 A-527: D-Ala2, D-Arg11, Leu15, Nle27, Gaba30-GHRH (1-30)-NH2 Our analogues were synthesized by solid phase peptide synthesis and were tested is two different in vitro systems and in rat pituitary cell cultures. A-495 and A-1741 were found to be the most active in releasing GH, however they showed different activities in the two different test systems. A-495 exhibited higher potency in the superfusion system (1.63 fold potency of the GHRH (1-29)-amide), while A-1741 evoked higher GH release from cultured pituitary cells (1.5-2.5 times higher than the GH-RH(1-44)-amide). The other analogues (A-515 and A-527) were found to be equipotent to the standard molecule. We can conclude that Nle27 and Gaba30 substitutions appeared to be a good modification in in vitro test systems, and Gaba30 substitution served as a good spacer during the synthesis, since it made the coupling of the C-terminal amino acids easier and produced quantitative coupling. In addition to the advantageous properties in the synthesis these modifications with or without D-Ala at the N-terminus increased the in vitro biological activity to 1.5-2.5 fold of the GHRH molecule. The additional substitution of Gly15 with Leu and Arg11 with D-Arg did not improve the in vitro GH-releasing activity of our analogues. A detailed in vivo investigation, which is essential for the future clinical use, has been performed and written in Part II of this paper.",
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T1 - New Gaba-containing analogues-of human growth hormone-releasing hormone (1-30)-amide

T2 - I. Synthesis and in vitro biological activity

AU - Mezo, I.

AU - Kovacs, M.

AU - Szoke, B.

AU - Szabo, E. Z.

AU - Horváth, J.

AU - Makara, G.

AU - Rappay, Gy

AU - Janáky, T.

AU - Teplan, I.

PY - 1993

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N2 - Analogues of human growth hormone-releasing hormone (1-30)-amide have been developed. All analogues have been modified in position 27 with Nle and with Gaba in position 30. Additional D-amino-acids have been inserted in the GHRH(1-30)-NH2 sequence: A-1741: Nle27, Gaba30-GH-RH (1-30)-NH2 A-495: D-Ala2, Nle27, Gaba30-GH-RH (1-30)-NH2 A-515: D Ala2, Leu15, Nle27, Gaba30-GH-RH (1-30)-NH2 A-527: D-Ala2, D-Arg11, Leu15, Nle27, Gaba30-GHRH (1-30)-NH2 Our analogues were synthesized by solid phase peptide synthesis and were tested is two different in vitro systems and in rat pituitary cell cultures. A-495 and A-1741 were found to be the most active in releasing GH, however they showed different activities in the two different test systems. A-495 exhibited higher potency in the superfusion system (1.63 fold potency of the GHRH (1-29)-amide), while A-1741 evoked higher GH release from cultured pituitary cells (1.5-2.5 times higher than the GH-RH(1-44)-amide). The other analogues (A-515 and A-527) were found to be equipotent to the standard molecule. We can conclude that Nle27 and Gaba30 substitutions appeared to be a good modification in in vitro test systems, and Gaba30 substitution served as a good spacer during the synthesis, since it made the coupling of the C-terminal amino acids easier and produced quantitative coupling. In addition to the advantageous properties in the synthesis these modifications with or without D-Ala at the N-terminus increased the in vitro biological activity to 1.5-2.5 fold of the GHRH molecule. The additional substitution of Gly15 with Leu and Arg11 with D-Arg did not improve the in vitro GH-releasing activity of our analogues. A detailed in vivo investigation, which is essential for the future clinical use, has been performed and written in Part II of this paper.

AB - Analogues of human growth hormone-releasing hormone (1-30)-amide have been developed. All analogues have been modified in position 27 with Nle and with Gaba in position 30. Additional D-amino-acids have been inserted in the GHRH(1-30)-NH2 sequence: A-1741: Nle27, Gaba30-GH-RH (1-30)-NH2 A-495: D-Ala2, Nle27, Gaba30-GH-RH (1-30)-NH2 A-515: D Ala2, Leu15, Nle27, Gaba30-GH-RH (1-30)-NH2 A-527: D-Ala2, D-Arg11, Leu15, Nle27, Gaba30-GHRH (1-30)-NH2 Our analogues were synthesized by solid phase peptide synthesis and were tested is two different in vitro systems and in rat pituitary cell cultures. A-495 and A-1741 were found to be the most active in releasing GH, however they showed different activities in the two different test systems. A-495 exhibited higher potency in the superfusion system (1.63 fold potency of the GHRH (1-29)-amide), while A-1741 evoked higher GH release from cultured pituitary cells (1.5-2.5 times higher than the GH-RH(1-44)-amide). The other analogues (A-515 and A-527) were found to be equipotent to the standard molecule. We can conclude that Nle27 and Gaba30 substitutions appeared to be a good modification in in vitro test systems, and Gaba30 substitution served as a good spacer during the synthesis, since it made the coupling of the C-terminal amino acids easier and produced quantitative coupling. In addition to the advantageous properties in the synthesis these modifications with or without D-Ala at the N-terminus increased the in vitro biological activity to 1.5-2.5 fold of the GHRH molecule. The additional substitution of Gly15 with Leu and Arg11 with D-Arg did not improve the in vitro GH-releasing activity of our analogues. A detailed in vivo investigation, which is essential for the future clinical use, has been performed and written in Part II of this paper.

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