Synthesis and biological activity of LH-RH antagonists modified in position 1.
As part of our studies on the design of more potent antagonists of the LH-RH (luteinizing hormone-releasing hormone) decapeptide, twelve new highly soluble D-Arg6-analogs have been synthesized. These peptides contain modifications in position 1 and are typified by the general formula (N-acetyl-X1, D-p-Cl-Phe2, D-Trp3, D-Arg6, D-Ala10) LH-RH. We have found that a lyophilic, aromatic substituent is required in position 1 in order to elicit antiovulatory activity at a dose as low as 3 micrograms. The larger the hydrophobic amino acid (X: p-Br-Phe, beta-Nal-2) in position 1, the higher is the antiovulatory activity that can be attained. Analogs with non-aromatic or hydrophilic amino acids (X: Gly, Leu, Arg, His, Glu) in position 1 generally have much lower activities in this series of LH-RH antagonists.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors* / Q000138:chemical synthesis / Q000494:pharmacology; D010060:Ovulation / Q000187:drug effects; D051381:Rats; D013329:Structure-Activity Relationship
D000596:Amino Acids; D007987:Gonadotropin-Releasing Hormone