Synthesis and biological properties of the 2-L-beta-(pyrazolyl-1)alanine analogs of luteinizing hormone-releasing hormone and thyrotropin-releasing hormone.

ABSTRACT

The luteinizing hormone-releasing hormone (LH-RH) analog, less thanGlu-Pyr(1)Ala-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2, and the thyrotropin-releasing hormone (TRH) analog, less thanGlu-Pyr(1)Ala-Pro-NH2, were synthesized by azide couplings of the dipeptide hydrazide, less thanGlu-Pyr(1)Ala-NHNH2, to the C-terminal octapeptide of LH-RH and to proline amide, respectively. In an ovariectomized, steroid-blocked rat assay, the LH-RH analog was found to have only 1% of the LH-releasing activity of the natural hormone. The TRH analog was 1.5 times more effective than TRH itself in releasing TSH in vivo from the anterior pituitary of mice. This peptide is one of two synthetic peptides so far discovered which are more potent than TRH.