beta-Sulfonamido gonadotropin-releasing hormone analogs: synthesis and evaluation of several parent hormone properties.

With the aim of producing long-acting analogs of gonadotropin releasing hormone (GnRH), four analogs, containing -X(6) (aa)psi(CH(2)SO(2)NH)-Leu(7) building unit (X(aa)=Gly, Ala, Val or Phe), and a reduced-size analog [Des-Tyr(5)]-GnRH which includes the unit Phe(5)psi(CH(2)SO(2)NH)-Leu(6), and [beta-Ala(6)]-GnRH were synthesized. The peptides were evaluated for their capacity to induce LH-release from rat pituitary cells and to withstand proteolysis by pituitary-derived enzymes, compared with the parent peptide GnRH. Albeit stable toward enzymatic degradation, the sulfonamido containing peptides were only marginally bioactive. [beta-Ala(6)]-GnRH, however, induced LH-release and bound to pituitary receptors nearly as efficiently as GnRH. This analog was also highly stable toward proteolysis suggesting that it may serve as a long-acting GnRH-analog.